Publications

Aftab, W, Mahmood, A, Guo, W, Yousaf, M, Tabassum, H, Huang, X, Liang, Z, Cao, A & Zou, R 2019, 'Polyurethane-based flexible and conductive phase change composites for energy conversion and storage', Energy Storage Materials, vol. 20, pp. 401-409.
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Ahmad, M, Yousaf, M, Nasir, A, Bhatti, IA, Mahmood, A, Fang, X, Jian, X, Kalantar-Zadeh, K & Mahmood, N 2019, 'Porous Eleocharis@MnPE Layered Hybrid for Synergistic Adsorption and Catalytic Biodegradation of Toxic Azo Dyes from Industrial Wastewater', Environmental Science & Technology, vol. 53, no. 4, pp. 2161-2170.
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Al-Soeidat, M, Lu, DD-C & Zhu, J 2019, 'An Analog BJT-Tuned Maximum Power Point Tracking Technique for PV Systems', IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 66, no. 4, pp. 637-641.
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© 2004-2012 IEEE. In this brief, an analog, bipolar junction transistor (BJT)-tuned voltage reference maximum power point tracking (MPPT) method for photovoltaic modules is proposed. The conventional fixed voltage reference method is the simplest method for tracking, but it does not obtain good MPPT efficiency because the maximum power point (MPP) voltage changes at different insolation levels. In reality, an approximately linear slope is formed when connecting the MPPs measured from the highest insolation level to the lowest. Utilizing this characteristic, a BJT, which has a similar electrical property, is used to implement a variable voltage reference that improves the accuracy of the MPP voltage when the insolation changes. The proposed circuit is simple and easy to implement, and it can track the MPP very quickly without the need for a digital controller or PID controller. Hence, the circuits cost and complexity are reduced. Experimental results are given to verify the feasibility of the proposed MPPT method.

Amjadipour, M, MacLeod, J, Lipton-Duffin, J, Tadich, A, Boeckl, JJ, Iacopi, F & Motta, N 2019, 'Electron effective attenuation length in epitaxial graphene on SiC', Nanotechnology, vol. 30, no. 2, pp. 025704-025704.
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The inelastic mean free path (IMFP) for carbon-based materials is notoriously challenging to model, and moving from bulk materials to 2D materials may exacerbate this problem, making the accurate measurements of IMFP in 2D carbon materials critical. The overlayer-film method is a common experimental method to estimate IMFP by measuring electron effective attenuation length (EAL). This estimation relies on an assumption that elastic scattering effects are negligible. We report here an experimental measurement of electron EAL in epitaxial graphene on SiC using photoelectron spectroscopy over an electron kinetic energy range of 50-1150 eV. We find a significant effect of the interface between the 2D carbon material and the substrate, indicating that the attenuation length in the so-called 'buffer layer' is smaller than for free-standing graphene. Our results also suggest that the existing models for estimating IMFPs may not adequately capture the physics of electron interactions in 2D materials.

Angeloski, A, Cortie, MB, Scott, JA, Bordin, DM & McDonagh, AM 2019, 'Conversion of single crystals of a nickel(II) dithiocarbamate complex to nickel sulfide crystals', Inorganica Chimica Acta, vol. 487, pp. 228-233.
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© 2018 Elsevier B.V. Single crystals of bis(κ2S,S′-di(isopropyl)dithiocarbamato) nickel(II) were utilized as a single source precursor for the formation of NiS via thermolysis. The complex decomposed at ∼250 °C to form α-NiS exclusively with no β-NiS detected. Analysis of the thermolysis regime using in situ techniques showed that the thermolysis occurs in a single step with the major volatile side-products being isopropyl-isothiocyanate and carbon disulfide. The resultant NiS was examined using SEM and TEM to reveal a retention of precursor crystal edge-length and angle relationships.

Angeloski, A, Rawal, A, Bhadbhade, M, Hook, JM, Schurko, RW & McDonagh, AM 2019, 'An Unusual Mercury(II) Diisopropyldithiocarbamate Coordination Polymer', Crystal Growth & Design, vol. 19, no. 2, pp. 1125-1133.
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Copyright © 2019 American Chemical Society. A new polymeric mercury(II) diisopropyldithiocarbamate complex was synthesized by the reaction of sodium diisopropyldithiocarbamate with excess HgCl 2 in water. The precise structure of the new compound was determined by single-crystal X-ray diffraction. A similar reaction, using a stoichiometric excess of the ligand, yielded the known monomeric bis(diisopropyldithiocarbamato)mercury(II) complex. The complexes could not be distinguished from each other by their solution-phase NMR spectra or their FTIR spectra. Solid-state NMR spectroscopy ( 199 Hg and 13 C) provided unambiguous data and showed that the monomeric complex and polymeric complex do not interconvert in solution or during crystal growth. Thermogravimetric experiments revealed quite different thermal decomposition behavior between the two compounds.

Belay, Y, Coetzee, L-C, Williams, DBG & Muller, A 2019, 'Synthesis of novel 1,2,3-triazole based polycarboxylic acid functionalised ligands for MOF systems', Tetrahedron Letters, vol. 60, no. 6, pp. 501-503.
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© 2019 Copper catalysed click reactions are excellent tools to generate various 1,2,3-triazole linked polytopic aromatic carboxylates. The general reaction route involves protection of the carboxylates before proceeding with the click reaction. These polycarboxylate azoles are conveniently prepared for potential utility as novel key building blocks for metal organic frameworks. In one case, the ligand crystallises into a solid structure containing 1D, 2D and 3D features, based on a zigzag 1D structure, a ‘chicken mesh’-like 2D structure and a 3D structure with very well-defined channels.

Bilokur, M, Gentle, AR, Arnold, MD, Cortie, MB & Smith, GB 2019, 'High temperature optically stable spectrally-selective Ti1xAlxN-based multilayer coating for concentrated solar thermal applications', Solar Energy Materials and Solar Cells, vol. 200, pp. 109964-109964.
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© 2019 Elsevier B.V. Spectrally-selective solar absorbing coatings based on the Ti1-xAlxN system were deposited using DC magnetron sputtering. Due to their refractory nature and very suitable optical properties, these were considered for high temperature solar thermal energy conversion. The composition of Ti1-xAlxN, (effectively, the Ti/Al ratio) was optimized to achieve a maximized solar absorptance. The optimum composition was then tested in a tandem absorber which included anti-reflective layers. A stainless steel substrate was used in order to simulate service in parabolic trough-based power plants that use stainless steel pipe to carry the heat-transfer fluid. High temperature annealing of the stack caused structural modifications but the solar absorptance of 92% was retained even after annealing at 900 °C.

Bodachivskyi, I, Kuzhiumparambil, U & Bradley G. Williams, D 2019, 'High Yielding Acid‐Catalysed Hydrolysis of Cellulosic Polysaccharides and Native Biomass into Low Molecular Weight Sugars in Mixed Ionic Liquid Systems', ChemistryOpen, vol. 8, no. 10, pp. 1316-1324.
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AbstractIonic media comprising 1‐butyl‐3‐methylimidazolium chloride and the acidic deep eutectic solvent choline chloride/oxalic acid as co‐solvent‐catalyst, very efficiently convert various cellulosic substrates, including native cellulosic biomass, into water‐soluble carbohydrates. The optimum reaction systems yield a narrow range of low molecular weight carbohydrates directly from cellulose, lignocellulose, or algal saccharides, in high yields and selectivities up to 98 %. Cellulose possesses significant potential as a renewable platform from which to generate large volumes of green replacements to many petrochemical products. Within this goal, the production of low molecular weight saccharides from cellulosic substances is the key to success. Native cellulose and lignocellulosic feedstocks are less accessible for such transformations and depolymerisation of polysaccharides remains a primary challenge to be overcome. In this study, we identify the catalytic activity associated with selected deep eutectic solvents that favours the hydrolysis of polysaccharides and develop reaction conditions to improve the outcomes of desirable low molecular weight sugars. We successfully apply the chemistry to raw bulk, non‐pretreated cellulosic substances.

Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'A Systematic Study of Metal Triflates in Catalytic Transformations of Glucose in Water and Methanol: Identifying the Interplay of Brønsted and Lewis Acidity', ChemSusChem, vol. 12, no. 14, pp. 3208-3208.
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AbstractInvited for this month′s cover is the group of Prof. Bradley Williams at the University of Technology Sydney. The image depicts the manifold products that can be selected in transformations of glucose through manipulation of the Brønsted or Lewis acidity of the catalyst. The Full Paper itself is available at 10.1002/cssc.201900292.

Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'A Systematic Study of Metal Triflates in Catalytic Transformations of Glucose in Water and Methanol: Identifying the Interplay of Brønsted and Lewis Acidity', ChemSusChem, vol. 12, no. 14, pp. 3263-3270.
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AbstractThe specific type of acidity associated with the given metal trifloromethanesulfonates (Brønsted or Lewis acidity) dramatically influences the course of reactions, and it is possible to select for disaccharides, fructose, methyl glucosides, or methyl levulinate. Glucose is transformed into a range of value‐added molecules in water and methanol under the action of acidic metal triflates as catalysts, including their analogous Brønsted acid‐assisted or Brønsted base‐modified systems. A systematic study is presented of a range of metal triflates in methanol and water, pinning down the preferred conditions to select for each product.

Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'Acid‐Catalysed Conversion of Carbohydrates into Furan‐Type Molecules in Zinc Chloride Hydrate', ChemPlusChem, vol. 84, no. 4, pp. 352-357.
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AbstractAcid‐catalysed conversion of biomass, specifically cellulose, holds promise to create value‐added, renewable replacements for many petrochemical products. We investigated an unusual acid‐catalysed transformation of cellulose and cellobiose in the biphasic solvent system zinc chloride hydrate (ionic liquid)/anisole. Here, furyl hydroxymethyl ketone and furfural are obtained as major products, which are valuable but less commonly formed in high yields in transformations of cellulosic substrates. We explored this chemistry in small‐scale model reactions and applied the optimised methods to the conversion of cellulose in bench‐scale processes. The optimum reaction system and preferred reaction conditions are defined to select for highly desirable furanoid products in the highest known yields (up to 46 %) directly from cellulose or cellobiose. The method avoids the use of added catalysts: the ionic solvent zinc chloride hydrate possesses the intrinsic acidity required for the hydrolysis and chemical transformation steps. The process involves inexpensive media for the catalytic conversion of cellulose into high‐value products under mild processing conditions.

Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'Metal triflates are tunable acidic catalysts for high yielding conversion of cellulosic biomass into ethyl levulinate', Fuel Processing Technology, vol. 195, pp. 106159-106159.
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© 2019 Metal triflates and their mixtures with Brønsted acids are excellent catalysts for the selective and high yielding transformation of microcrystalline cellulose into ethyl levulinate, in ethanol, producing synergistic catalyst effects in some instances. The pretreatment of raw and unrefined cellulosic materials with a deep eutectic solvent enables similarly excellent catalysed conversion thereof into ethyl levulinate in superb yield (up to 75%) and selectivity (up to 88%). When using fermentation-derived ethanol, the product possesses 100% renewable content.

Bodachivskyi, I, Kuzhiumparambil, U & Williams, DBG 2019, 'The role of the molecular formula of ZnCl₂·nH₂O on its catalyst activity: a systematic study of zinc chloride hydrates in the catalytic valorisation of cellulosic biomass', Catalysis Science & Technology, vol. 9, no. 17, pp. 4693-4701.
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We show the efficient and direct transformation of a range of low value cellulosic substrates such as lignocellulose and algal biomass, into higher value chemicals, including low molecular weight reducing saccharides and furanoid products.

Cao, Y, Wang, L, Wang, C, Su, D, Liu, Y & Hu, X 2019, 'Photoelectrochemical determination of malathion by using CuO modified with a metal-organic framework of type Cu-BTC', Microchimica Acta, vol. 186, no. 7.
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© 2019, Springer-Verlag GmbH Austria, part of Springer Nature. A photoelectrochemical (PEC) sensor was constructed for the detection of non-electroactive malathion. It is based on the use of a hierarchical CuO material derived from a Cu-BTC metal-organic framework (where BTC stands for benzene-1,3,5-tricarboxylic acid). The modified CuO was obtained by calcination of Cu-BTC at a high temperature (300 °C) and possesses a high photocurrent conversion efficiency. Under irradiation with visible light and in the presence of malathion, the formation of the CuO-malathion complex on the CuO gave rise to an increase in steric hindrance. This results in a decrease in photocurrent. This novel PEC detection method has a lower detection limit of 8.6 × 10−11 mol L−1 and a wide linear range (1.0 × 10−10 ~ 1.0 × 10−5 mol L−1). [Figure not available: see fulltext.]

Chen, F, Hua, W, Huang, W, Zhu, J & Tong, M 2019, 'Open-circuit Fault-tolerant Strategies for a Five-phase Flux-switching Permanent Magnet Motor Based on Model Predictive Torque Control Method', Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering, vol. 39, no. 2, pp. 337-346.
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To improve the fault-tolerant performance of five-phase flux-switching permanent magnet (FSPM) motor under open-circuit fault, the model predictive torque control (MPTC) was investigated. For the comprehensive control of the fundamental and harmonic subspaces, the torque, the amplitude of the stator flux linkage and the current in the harmonic subspace were employed as the control targets. Moreover, a pre-selective method, which was inspired by the switching table in the direct torque control, was developed to reduce the number of active switching states as well as the computational burden. By combining the sector where the stator flux linkage is located with the variations of the torque and the stator flux linkage magnitude, the specific voltage vectors instead of all vectors were determined as the vector candidates. As a result, the number of traversals was effectively reduced, and the computational burden was significantly alleviated. Consequently, the effectiveness of the proposed MPTC methods had been validated by simulations and experiments.

Chen, Y, Zhang, W, Zhou, D, Tian, H, Su, D, Wang, C, Stockdale, D, Kang, F, Li, B & Wang, G 2019, 'Co–Fe Mixed Metal Phosphide Nanocubes with Highly Interconnected-Pore Architecture as an Efficient Polysulfide Mediator for Lithium–Sulfur Batteries', ACS Nano, vol. 13, no. 4, pp. 4731-4741.
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Copyright © 2019 American Chemical Society. Lithium-sulfur (Li-S) batteries have been regarded as one of the most promising candidates for next-generation energy storage owing to their high energy density and low cost. However, the practical deployment of Li-S batteries has been largely impeded by the low conductivity of sulfur, the shuttle effect of polysulfides, and the low areal sulfur loading. Herein, we report the synthesis of uniform Co-Fe mixed metal phosphide (Co-Fe-P) nanocubes with highly interconnected-pore architecture to overcome the main bottlenecks of Li-S batteries. With the highly interconnected-pore architecture, inherently metallic conductivity, and polar characteristic, the Co-Fe-P nanocubes not only offer sufficient electrical contact to the insulating sulfur for high sulfur utilization and fast redox reaction kinetics but also provide abundant adsorption sites for trapping and catalyzing the conversion of lithium polysulfides to suppress the shuttle effect, which is verified by both the comprehensive experiments and density functional theory calculations. As a result, the sulfur-loaded Co-Fe-P (S@Co-Fe-P) nanocubes delivered a high discharge capacity of 1243 mAh g -1 at 0.1 C and excellent cycling stability for 500 cycles with an average capacity decay rate of only 0.043% per cycle at 1 C. Furthermore, the S@Co-Fe-P electrode showed a high areal capacity of 4.6 mAh cm -2 with superior stability when the sulfur loading was increased to 5.5 mg cm -2 . More impressively, the prototype soft-package Li-S batteries based on S@Co-Fe-P cathodes also exhibited superior cycling stability with great flexibility, demonstrating their great potential for practical applications.

Choi, S, Seo, DH, Kaiser, MR, Zhang, C, van der laan, T, Han, ZJ, Bendavid, A, Guo, X, Yick, S, Murdock, AT, Su, D, Lee, BR, Du, A, Dou, SX & Wang, G 2019, 'WO₃ nanolayer coated 3D-graphene/sulfur composites for high performance lithium/sulfur batteries', Journal of Materials Chemistry A, vol. 7, no. 9, pp. 4596-4603.
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WO₃/graphene composite minimizes the polysulfide dissolution problem in the lithium–sulfur (Li–S) battery systems while exhibiting an excellent battery performance.

Dou, Y, Li, Y, Zhu, J, Wang, L, Li, A & Zhang, C 2019, 'High-frequency effects analysis of windings in magnetic properties tester with nanocrystalline core', International Journal of Applied Electromagnetics and Mechanics, vol. 61, pp. S81-S88.
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Du, G, Xu, W, Zhu, J & Huang, N 2019, 'Rotor Stress Analysis for High-Speed Permanent Magnet Machines Considering Assembly Gap and Temperature Gradient', IEEE Transactions on Energy Conversion, vol. 34, no. 4, pp. 2276-2285.
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© 1986-2012 IEEE. For predesigned high speed permanent magnet machines (HSPMMs), the accurate evaluation of rotor strength is extremely important to ensure the reliability of the rotor at high speeds. This paper mainly addresses a comprehensive study on the rotor stress of one predesigned HSPMM with predetermined dimensions, by considering the effect of the assembly gaps between the segmented PMs and between the PMs and the pole filler, and temperature gradient in the rotor. First, the influence of the assembly gaps for different rotor structures, different PM segments, different pole fillers, different material properties on the rotor stress are summarized by Ansys Workbench. Then, the full investigation on the rotor stress distribution is performed under the influence of the rotor temperature gradient, which is obtained by Ansys-Cfx. And then, by considering the non-isothermal distribution of rotor temperature, the 3D temperature-stress coupling analysis is performed to obtain the optimal sleeve thickness. After fabricating the prototype, continuous operation test is carried out, which validates the effectiveness of aforementioned theoretical analysis.

Duan, N, Xu, W, Li, Y, Wang, S & Zhu, J 2019, 'A Temperature and Stress Dependent Hysteresis Model with Experiment Validation', Diangong Jishu Xuebao/Transactions of China Electrotechnical Society, vol. 34, no. 13, pp. 2686-2692.
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The design and performance analysis of the electrical equipment usually involve the coupling of electrical, magnetic, thermal, mechanical and other physical fields. With the development of numerical calculation technology of electromagnetic field and the improvement of computer performance, the electromagnetic field numerical simulation software has been widely used to analyze the coupling problem of electromagnetic field, thermal field and mechanical field. The magnetic properties of magnetic material under work conditions will be influenced by some non-magnetic factors, such as temperature and stress. However, these characteristics are difficult to be simulated by the traditional hysteresis models. In this paper, based on the microscopic magnetization mechanisms of magnetic materials, a hysteresis elemental operator, which contains two easy axes and two hard axes, has been presented. Besides, with the help of the energy minimum principle, the octagonal law which can determine the orientation of the magnetization has been introduced. By taking into account the differences between the laboratory conditions and the practical engineering manufacturing and operation, the temperature-depended saturation magnetization, temperature-depended anisotropy, and stress-depended distribution function are introduced to the hysteresis elemental operator. With the employment of the Gaussian-Gaussian distribution function and the interaction field, a temperature and stress dependent hysteresis model is proposed to simulate the magnetic properties under different temperature and stress conditions. Finally, by comparing the simulation results with the experimental measurement results, the effectiveness and viability of this proposed hysteresis model have been confirmed.

Gao, P, Wang, X, Huang, Z & Yu, H 2019, '¹¹B NMR Chemical Shift Predictions via Density Functional Theory and Gauge-Including Atomic Orbital Approach: Applications to Structural Elucidations of Boron-Containing Molecules', ACS Omega, vol. 4, no. 7, pp. 12385-12392.
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© 2019 American Chemical Society. 11B nuclear magnetic resonance (NMR) spectroscopy is a useful tool for studies of boron-containing compounds in terms of structural analysis and reaction kinetics monitoring. A computational protocol, which is aimed at an accurate prediction of 11B NMR chemical shifts via linear regression, was proposed based on the density functional theory and the gauge-including atomic orbital approach. Similar to the procedure used for carbon, hydrogen, and nitrogen chemical shift predictions, a database of boron-containing molecules was first compiled. Scaling factors for the linear regression between calculated isotropic shielding constants and experimental chemical shifts were then fitted using eight different levels of theory with both the solvation model based on density and conductor-like polarizable continuum model solvent models. The best method with the two solvent models yields a root-mean-square deviation of about 3.40 and 3.37 ppm, respectively. To explore the capabilities and potential limitations of the developed protocols, classical boron-hydrogen compounds and molecules with representative boron bonding environments were chosen as test cases, and the consistency between experimental values and theoretical predictions was demonstrated.

Gao, X, Feng, J, Su, D, Ma, Y, Wang, G, Ma, H & Zhang, J 2019, 'In-situ exfoliation of porous carbon nitride nanosheets for enhanced hydrogen evolution', Nano Energy, vol. 59, pp. 598-609.
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© 2019 Elsevier Ltd The development of water splitting technology is severely impeded by the limited strategies for preparing efficient photocatalyst with optimal structure. Herein, a facile structure and doping engineering strategy is proposed to obtain the atomic-thin mesoporous graphite carbon nitride (g-C 3 N 4 ) nanosheets with a large specific surface area of 212.5 m 2 g −1 , an ultra-large pore volume of 1.55 cm 3 g −1 , high C and O contents of ∼51.4 and 4.8% via an acid-assisted exfoliation route without any hard templates. The theoretical calculation reveals that the introduction of additional C/O atoms into g-C 3 N 4 matrix would boost the charge transfer rate and charge separation efficiency due to the enhanced electronic polarization effect (Bader Charge) and shortened bond lengths. Additionally, the electronic conductivity is demonstrated to be enhanced due to the formation of delocalized π-bonding both experimentally and theoretically. The synergic contribution of textural and electronic features renders an excellent photoelectrochemical (PEC) performance with 50–60 times larger photocurrent in comparison with the pristine g-C 3 N 4 and high hydrogen evolution rates of 830.1 and 115.5 μmol g −1 h −1 under the solar- and visible-light irradiation, respectively. This in-situ exfoliation approach demonstrates a facile yet efficient method to synthesize highly porous carbon nitride materials with optimal structure and composition for efficient water splitting.

Gao, X, Zhou, D, Chen, Y, Wu, W, Su, D, Li, B & Wang, G 2019, 'Strong charge polarization effect enabled by surface oxidized titanium nitride for lithium-sulfur batteries', Communications Chemistry, vol. 2, no. 1.
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AbstractThe commercialization of high-energy-density and low-cost lithium-sulfur batteries has been severely impeded by capacity fading and electrochemical polarization. Here we report a strategy to entrap polysulfides and boost the cathodic redox kinetics by embedding the surface oxidized quantum-dot-size TiN (TiN-O) within the highly ordered mesoporous carbon matrix. While the carbon scaffold offers sufficient electrical contact to the insulate sulfur, benefiting the full usage of sulfur and physical confinement of polysulfides. The surface oxygen renders TiN-O with a strong charge polarization effect for polysulfides via S-O-Ti bond as verified experimentally and theoretically. The suppressed shuttle effect and high lithium ion diffusion coefficient (7.9 × 10−8 cm2 s−1) lead to a high capacity of 1264 mA h g−1 at 0.2 C with a negligible capacity fading rate of 0.06% per cycle. Additionally, TiN-O based prototype soft-package cells also exhibit excellent cycling stability with flexibility, demonstrating their potential for practical applications.

Gharib, DH, Lock, P, Moulton, SE, Malherbe, F & Langford, SJ 2019, 'Molecular Design of Core Substituted Naphthalene Diimides for the Exfoliation of Graphite to Graphene in Chloroform', ChemNanoMat, vol. 5, no. 10, pp. 1303-1310.
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AbstractA significant challenge of liquid phase exfoliation (LPE) of graphite to yield graphene resides in the fact that most conventional solvents used are high boiling points and thus extremely difficult to eliminate, especially during processing of graphene into composites or films. Here, we advance the ability to produce high yield graphene in a low boiling point organic solvent, chloroform, using core‐substituted naphthalene diimides (cNDIs). Through the use of cNDIs it is possible to obtain high graphene concentrations of up to 0.13 mg/mL in chloroform. This yield represents a 69% improvement from graphene yields previously obtained in chloroform using unsubstituted NDIs. Characterisation of the products by UV‐Vis, X‐ray diffraction (XRD), Transmission electron microscopy (TEM), Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS) support the use of cNDIs as an appropriate exfoliating agent in chloroform.

Guo, X, Zhang, J, Zhao, Y, Sun, B, Liu, H & Wang, G 2019, 'Ultrathin Porous NiCo₂O₄ Nanosheets for Lithium–Oxygen Batteries: An Excellent Performance Deriving from an Enhanced Solution Mechanism', ACS Applied Energy Materials, vol. 2, no. 6, pp. 4215-4223.
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© Copyright 2019 American Chemical Society. Lithium-oxygen batteries are of interest for long-range electric vehicles owing to their high theoretical energy density. However, the poor cycling performance and low round-trip efficiency deriving from the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics severely impede their practical application. Ingenious design of cathode catalysts is imperative to overcome these challenges. Here, we report ultrathin porous NiCo2O4 nanosheets with abundant oxygen vaccines as an efficient cathode catalyst toward both OER and ORR for Li-O2 batteries. From combined theoretical calculation with experimental results, a unique enhanced solution mechanism is proposed in the ether-based electrolyte system. Benefiting from the porous 2D architecture of the cathode and the hierarchical toroidal products, the Li-O2 batteries using NiCo2O4 cathodes deliver a high discharge capacity of 16 400 mAh g-1 at 200 mA g-1 and an excellent cycling performance up to 150 cycles with a restricted capacity of 1000 mAh g-1.

Han, N, Wei, Q, Tian, H, Zhang, S, Zhu, Z, Liu, J & Liu, S 2019, 'Highly Stable Dual‐Phase Membrane Based on Ce_0.9Gd_0.1O_2–δ—La₂NiO_4+δ for Oxygen Permeation under Pure CO₂ Atmosphere', Energy Technology, vol. 7, no. 5, pp. 1800701-1800701.
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Dense oxygen ion–conducting ceramic membranes with CO2 resistance can promote many advanced applications such as membrane reactors for green chemical synthesis and oxy‐fuel combustion for clean energy delivery. The state‐of‐the‐art perovskite oxide membranes are characterized by their high O2 flux but low stability in a CO2‐containing atmosphere. To solve this problem, dual‐phase membranes have captured the imagination of researchers. Herein, a novel dual‐phase hollow fiber membrane with a composition of 40 wt% Ce0.9Gd0.1O2–δ (GDC)–60 wt% La2NiO4+δ (LNO) is developed via a combined phase inversion sintering process. During the high temperature treatment, La‐doping behavior is observed with La leaching out from the LNO phase and diffusing into the GDC phase. This dual phase membrane displays the O2 flux of 1.47 at 950 °C, which is reduced by 10% to 1.31 mL min−1 cm−2 when the sweep gas is switched from helium to pure CO2. Such minor O2 flux reduction is due to the strong CO2 adsorption on membrane surface occupying the O2 vacancies without permanent membrane damage, which is fully eliminated by an inert gas purge. Such a robust dual‐phase membrane exhibits the potential to overcome the low stability problem under the CO2‐containing atmosphere.

Han, R, Khan, MH, Angeloski, A, Casillas, G, Yoon, CW, Sun, X & Huang, Z 2019, 'Hexagonal Boron Nitride Nanosheets Grown via Chemical Vapor Deposition for Silver Protection', ACS Applied Nano Materials, vol. 2, no. 5, pp. 2830-2835.
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© 2019 American Chemical Society. In this study, hexagonal boron nitride nanosheets (h-BNNS) have been grown on polycrystalline silver substrates via chemical vapor deposition (CVD) using ammonia borane as a precursor. The h-BNNS are of few-atomic-layer thickness and form continuous coverage over the whole Ag substrate. The atomically thin coating poses negligible interference to the reflectivity in the UV-visible range. The nanosheet coating also proves very effective in protecting Ag foil chemically. In contrast to bare Ag foil, the coated foil displayed only minor decolorization under high concentration of H2S. The study indicates that h-BNNS can be a promising protective coating for Ag based items such as jewelry or mirrors used in astronomical telescopes.

He, T, Wu, M, Lu, DD-C, Aguilera, RP, Zhang, J & Zhu, J 2019, 'Designed Dynamic Reference With Model Predictive Control for Bidirectional EV Chargers', IEEE Access, vol. 7, pp. 129362-129375.
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© 2013 IEEE. This paper presents a finite control set model predictive control (MPC) using a designed dynamic reference for bidirectional electric vehicle (EV) chargers. In the conventional MPC scheme, a PI controller is involved to generate an active power reference from the DC voltage reference. It is hard to find one fixed set of coefficients for all working conditions. In this paper, a designed dynamic reference based MPC strategy is proposed to replace the PI control loop. In the proposed method, a DC voltage dynamic reference is developed to formulate the inherent relationship between the DC voltage reference and the active power reference. Multi-objective control can be achieved in the proposed scheme, including controlling of the DC voltage, battery charging/discharging current, active power and reactive power, independently. Bidirectional power flow is operated effectively between the EV- and the grid-side. Experimental results are obtained from a laboratory three-phase two-stage bidirectional EV charger controlled by dSPACE DS1104. The results show that fast dynamic and good steady state performance of tracking the above objectives can be achieved with the proposed method. Compared with the system performance obtained by the conventional MPC method, the proposed method generates less active power ripples and produces a better grid current performance.

He, T, Zhu, J, Lu, DD-C & Zheng, L 2019, 'Modified Model Predictive Control for Bidirectional Four-Quadrant EV Chargers With Extended Set of Voltage Vectors', IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 7, no. 1, pp. 274-281.
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© 2013 IEEE. This paper presents a modified model predictive control (MMPC) for bidirectional power flow control between the electric vehicle (EV) chargers and the main grid. In contrast to the conventional finite control set MPC which selects an optimal switching state from eight possible voltage vectors, the proposed MMPC is based on the application of an optimal voltage vector chosen from an extended set of 20 modulated voltage vectors with a fixed duty ratio. To reduce the computational burden introduced by the increased number of voltage sets, a preselection algorithm is developed for the MMPC method. Six voltage vectors are preselected from the 20 sectors. Due to the increased number of the voltage space vectors, the grid currents and active and reactive power performance can be improved by using the proposed MMPC scheme. Both the conventional and proposed methods are compared through experimental test results of a two-level three-phase off-board EV charger.

Hu, J, Li, Z, Zhu, J & Guerrero, JM 2019, 'Voltage Stabilization: A Critical Step Toward High Photovoltaic Penetration', IEEE Industrial Electronics Magazine, vol. 13, no. 2, pp. 17-30.
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© 2007-2011 IEEE. The increasing photovoltaic (PV) power sources connected to low-voltage (LV) distribution networks generate a new grid environment featuring various types of power generations near consumers and bidirectional active and reactive power flows. However, the large-scale deployment of PVs is hindered by the power quality problems, particularly voltage deviation. To overcome this obstacle, proper mitigation techniques should be developed to eliminate the negative impacts of high-PV penetration in LV networks. This article provides an in-depth review of recently developed technologies that prevent voltage deviation in LV grids with PVs. Following an investigation of the voltage fluctuation phenomena along the distribution feeder due to variable PV output and power demand, the mathematical relationship between power flow and voltage level is revealed. The solutions that mitigate the voltage variation are then investigated and classified. Their effectiveness, advantages, and disadvantages are illustrated. Finally, the current trend in grid integration of PVs and other distributed generators (DGs) under future grid framework is discussed.

Huang, W, Hua, W, Chen, F, Qi, J & Zhu, J 2019, 'Performance Improvement of Model Predictive Current Control of Fault-Tolerant Five-Phase Flux-Switching Permanent Magnet Motor Drive', IEEE Transactions on Industry Applications, vol. 55, no. 6, pp. 6001-6010.
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© 1972-2012 IEEE. To improve the fault-tolerant performance of a five-phase flux-switching permanent magnet (FSPM) motor drive under open-circuit fault (OCF) condition, a model predictive current control (MPCC) with pre-selective method and duty ratio control (DRC) technology is proposed and investigated in this paper. First, on the principle of minimizing harmonic voltages in x-y subspace, two zero switching states and the switching state, which generates a larger voltage vector in α-β subspace are pre-selected. Second, voltage vector references in α-β subspace and x-y subspace are predicted to further select active voltage vector candidates. Consequently, the number of current predictions has been significantly reduced, resulting in the alleviation of the computational complexity and the increase of sampling frequency. Third, the DRC approach is applied in conjunction with the pre-selection-based MPCC to improve the steady-state performance. Finally, the effectiveness of the proposed MPCC method for the OCF tolerant five-phase FSPM motor drive is validated by comparative experiments.

Hundal, AK, Agarwal, A, Jameel, M, Chen, J-Y, Li, J-L, Jones, L, Kaur, N, Langford, S & Gupta, A 2019, 'Improvement of the optoelectronic and photovoltaic properties of a cyanopyrid-2,6-dione-based donor via molecular engineering', Dyes and Pigments, vol. 170, pp. 107661-107661.
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Huo, J, Chen, Y, Liu, Y, Guo, J, Lu, L, Li, W, Wang, Y & Liu, H 2019, 'Bifunctional iron nickel phosphide nanocatalysts supported on porous carbon for highly efficient overall water splitting', Sustainable Materials and Technologies, vol. 22, pp. e00117-e00117.
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© 2019 The development of low-cost and earth-abundant materials for efficient oxygen and hydrogen evolution is critical for water splitting as a feasible energy conversion system. Metallic phosphides as promising bifunctional catalysts for water splitting tend to aggregate during the preparation and application. Thus, constructing metal phosphide-based composites with well-exposed active sites and stable structure is essential. Here, bi-metallic iron nickel phosphide nanoparticles (NPs) loaded on three-dimensional (3D) porous carbon (denoted as FexNi2-xP (0 < x < 2)) is synthesized through a facile co-deposition method followed by in situ phosphidation. The interconnected porous carbon with large specific area, abundant microporous and oxygen-containing functional groups contribute to the generation of ultra-small Fe–Ni–P NPs by confining growth of Fe–Ni layered double hydroxide (Fe–Ni–LDH) precursor. The ultra-small FexNi2-xP NPs loaded on 3D interconnected porous carbon with large active surface area and high conductivity can offer abundant catalytic active sites, facilitate mass transport and optimize electronic configuration, thereby promoting the reaction kinetics and accelerating catalytic performance. By tailoring the Ni/Fe ratios, the optimal bimetallic phosphide exhibits a small overpotential of 210 mV at current density of 10 mA cm−2 for oxygen evolution reaction. When applying for water splitting as cathode and anode materials in an alkaline electrolyzer, the potential of 1.63 V is required to reach 10 mA cm−2. The catalyst obtained from this strategy is a promising bi-functional catalyst for water splitting.

Iacopi, F & McIntosh, M 2019, 'Opportunities and perspectives for green chemistry in semiconductor technologies', Green Chemistry, vol. 21, no. 12, pp. 3250-3255.
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Semiconductor technologies offer a plethora of technological challenges and opportunities for a more extensive implementation of green chemistry principles.

Insuasty, A, Carrara, S, Tang, L, Forsyth, C, Hogan, CF, McNeill, CR & Langford, SJ 2019, 'A Family of Heterocyclic Naphthalene Diimide (NDI) Analogues: Comparing Parent Isoquinoline Diimides and Phthalazine Diimides with NDI', ChemPlusChem, vol. 84, no. 10, pp. 1638-1642.
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AbstractParent isoquinoline diimide (IQDI) and phthalazine diimide (PTDI), as two new heterocyclic analogues of naphthalene diimides (NDIs), have been synthesized through an oxidative strategy in 35–79 % yield. X‐ray crystallography has been used to support the formation of IQDI, which also show fluorescence quantum yields of 3.5 %. The electrochemical and electrical properties of these molecules have been studied. The electrochemical results show an interesting trend in first reduction potential PTDI<IQDI<NDI and 0.1 eV changes in the optical band gap (Eg) leading to the trend IQDI<NDI<PTDI, as supported by DFT calculations. While initial top gate OFET devices yield charge mobilities less than NDIs, the basis of this study intimates that IQDIs and PTDIs hold promise for applications commensurate with NDIs.

Insuasty, A, Maniam, S & Langford, SJ 2019, 'Frontispiece: Recent Advances in the Core‐Annulation of Naphthalene Diimides', Chemistry – A European Journal, vol. 25, no. 29.
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Insuasty, A, Maniam, S & Langford, SJ 2019, 'Recent Advances in the Core‐Annulation of Naphthalene Diimides', Chemistry – A European Journal, vol. 25, no. 29, pp. 7058-7073.
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AbstractThis review focuses on describing all known synthetic strategies leading to core‐annulation of naphthalene diimides (NDIs). Strategies presented involve the formation of four‐, five‐ and six‐membered ring annulations bearing different heteroatomic and carbocyclic derivatives, including annulenes. The core‐annulation method opens the possibility for obtaining designer molecules with tuneable electronic characteristics such as a reduced energy band gap, and enhanced intermolecular overlap of π‐systems that improve electronic coupling between molecules—which is highly desirable for charge transport properties summarised in the final pages for applications in electronic devices such as organic field‐effect transistors (OFETs) and organic photovoltaic (OPV) cells. Molecular recognition in pH and fluoride sensing, or as a DNA probe, are some of additional applications of core‐annulated NDIs presented here. Additionally, recent advances in core modification of NDIs are presented, opening an entire new chemical avenue to be explored. Finally, the outlook on the future prospect of annulated NDIs in various applications is summarised.

Jafari, M, Malekjamshidi, Z, Lu, DD-C & Zhu, J 2019, 'Development of a Fuzzy-Logic-Based Energy Management System for a Multiport Multioperation Mode Residential Smart Microgrid', IEEE Transactions on Power Electronics, vol. 34, no. 4, pp. 3283-3301.
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IEEE In this paper a grid-tied residential smart micro-grid topology is proposed which integrates energies of a PV, a fuel cell and a battery bank to supply the local loads through a combination of electric and magnetic buses. In contrast to multiple-converter based micro-grids with a common electric bus, using a multi-port converter with a common magnetic bus can effectively reduce the number of voltage conversion stages, size and cost of the micro-grid and isolates the conversion ports. The resultant topology utilizes a centralized system level control which leads to the faster and more flexible energy management. The proposed micro-grid is able to operate in multiple grid-connected and off-grid operation modes. A fuzzy controlled energy management unit is designed to select the appropriate operation mode considering both real-time and long-term-predicted data of the system. A mode transition process is designed to smooth the mode variation by using a state transition diagram and bridging modes. To improve the micro-grid operation performance, appropriate control techniques such as synchronized bus-voltage balance are used. A prototype of the proposed micro-grid is developed and experimentally tested for three different energy management scenarios. Energy distribution and energy cost analysis are performed to validate the proposed control method.

Jian, X, Wang, H, Rao, G, Jiang, L, Wang, H, Subramaniyam, CM, Mahmood, A, Zhang, W, Xiang, Y, Dou, SX, Zhou, Z, Hui, D, Kalantar-Zadeh, K & Mahmood, N 2019, 'Self-tunable ultrathin carbon nanocups as the electrode material of sodium-ion batteries with unprecedented capacity and stability', Chemical Engineering Journal, vol. 364, pp. 578-588.
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Johnson, B, Chang, L, Afridi, K, Ali, MH, von Appen, J, Chen, Y-M, Davoudi, A, Dhople, S, Enslin, JH, Flicker, J, Islam, MR, Koutroulis, E, Kim, KA, Li, Y, Liserre, M, Long, T, Lu, X, Mattavelli, P, Rodriguez, P, Ruan, X, Suntio, T, Wang, H, Xu, D, Xu, W, Yazdani, A, Zeineldin, H & Zhu, J 2019, 'Guest Editorial Joint Special Section on Power Conversion & Control in Photovoltaic Power Plants', IEEE Transactions on Energy Conversion, vol. 34, no. 1, pp. 159-160.
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King, AT, Hiscocks, HG, Matesic, L, Bhadbhade, M, Bishop, R & Ung, AT 2019, 'Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate', Beilstein Journal of Organic Chemistry, vol. 15, pp. 1347-1354.
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The one-pot reaction of 2,6-bis(diphenylmethyl)-4-methoxyaniline with tert-butylnitrite, BTEAC and DABSO in the presence of CuCl2 provided an unexpected 3H-indazole product 8. The structure of the compound was determined by HRMS, IR, NMR and further confirmed by single crystal X-ray crystallography. The compound crystallises in the triclinic P-1 space group, with unit cell parameters a = 9.2107 (4), b = 10.0413 (5), c = 14.4363 (6) Å, α = 78.183 (2), β = 87.625 (2), γ = 71.975 (2)°. The formation of 8 proceeded through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate 9. The molecules of 8 are organised by edge–face Ar–H···π, face–face π···π, and bifurcated OCH2–H···N interactions. In addition to these, there are Ar–H···H–Ar close contacts, (edge–edge and surrounding inversion centres) arranged as infinite tapes along the a direction.

King, DJM, Cheung, STY, Humphry-Baker, SA, Parkin, C, Couet, A, Cortie, MB, Lumpkin, GR, Middleburgh, SC & Knowles, AJ 2019, 'High temperature, low neutron cross-section high-entropy alloys in the Nb-Ti-V-Zr system', Acta Materialia, vol. 166, pp. 435-446.
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© 2019 Acta Materialia Inc. High-entropy alloys (HEAs) with high melting points and low thermal neutron cross-section are promising new cladding materials for generation III+ and IV power reactors. In this study a recently developed high throughput computational screening tool Alloy Search and Predict (ASAP) has been used to identify the most likely candidate single-phase HEAs with low thermal neutron cross-section, from over a million four-element equimolar combinations. The selected NbTiVZr HEA was further studied by density functional theory (DFT) for moduli and lattice parameter, and by CALPHAD to predict phase formation with temperature. HEAs of NbTiVZr x (x = 0.5, 1, 2) were produced experimentally, with Zr varied as the dominant cross-section modifier. Contrary to previous experimental work, these HEAs were demonstrated to constitute a single-phase HEA system; a result obtained using a faster cooling rate following annealing at 1200 °C. However, the beta (BCC) matrix decomposed following aging at 700 °C, into a combination of nano-scale beta, alpha (HCP) and C15 Laves phases.

Kusuma, KD, Griffith, R, Harry, EJ, Bottomley, AL & Ung, AT 2019, 'Analysis of FtsZ Crystal Structures Towards a New Target for Antibiotics', Australian Journal of Chemistry, vol. 72, no. 3, pp. 184-193.
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The bacterial cell division protein FtsZ is conserved in most bacteria and essential for viability. There have been concerted efforts in developing inhibitors that target FtsZ as potential antibiotics. Key to this is an in-depth understanding of FtsZ structure at the molecular level across diverse bacterial species to ensure inhibitors have high affinity for the FtsZ target in a variety of clinically relevant pathogens. In this study, we show that FtsZ structures differ in three ways: (1) the H7 helix curvature; (2) the dimensions of the interdomain cleft; and (3) the opening/closing mechanism of the interdomain cleft, whereas no differences were observed in the dimensions of the nucleotide-binding pocket and T7 loop. Molecular dynamics simulation may suggest that there are two possible mechanisms for the process of opening and closing of the interdomain cleft on FtsZ structures. This discovery highlights significant differences between FtsZ structures at the molecular level and this knowledge is vital in assisting the design of potent FtsZ inhibitors.

Kusuma, KD, Payne, M, Ung, AT, Bottomley, AL & Harry, EJ 2019, 'FtsZ as an Antibacterial Target: Status and Guidelines for Progressing This Avenue', ACS Infectious Diseases, vol. 5, no. 8, pp. 1279-1294.
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© 2019 American Chemical Society. The disturbing increase in the number of bacterial pathogens that are resistant to multiple, or sometimes all, current antibiotics highlights the desperate need to pursue the discovery and development of novel classes of antibacterials. The wealth of knowledge available about the bacterial cell division machinery has aided target-driven approaches to identify new inhibitor compounds. The main division target being pursued is the highly conserved and essential protein FtsZ. Despite very active research on FtsZ inhibitors for several years, this protein is not yet targeted by any commercial antibiotic. Here, we discuss the suitability of FtsZ as an antibacterial target for drug development and review progress achieved in this area. We use hindsight to highlight the gaps that have slowed progress in FtsZ inhibitor development and to suggest guidelines for concluding that FtsZ is actually the target of these molecules, a key missing link in several studies. In moving forward, a multidisciplinary, communicative, and collaborative process, with sharing of research expertise, is critical if we are to succeed.

Lei, G, Liu, C, Li, Y, Chen, D, Guo, Y & Zhu, J 2019, 'Robust Design Optimization of a High-Temperature Superconducting Linear Synchronous Motor Based on Taguchi Method', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2, pp. 1-6.
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© 2002-2011 IEEE. This paper investigates the efficient robust design and optimization of a high-Temperature superconducting (HTS) linear synchronous motor by using the Taguchi parameter design approach. The manufacturing tolerances of the HTS magnets, primary iron core and the air gap are considered in the robust design to ensure that the optimal design is less sensitive to these uncertainties. To overcome the disadvantages of the conventional Taguchi parameter design approach, a sequential Taguchi robust optimization method is presented for improvement of the motor performance and manufacturing quality. The proposed method is efficient because it holds the advantages of both Taguchi method and sequential optimization strategy. It can significantly increase the average thrust and decrease the thrust ripple of the investigated HTS linear synchronous motor.

Li, G, Hu, J, Li, Y & Zhu, J 2019, 'An Improved Model Predictive Direct Torque Control Strategy for Reducing Harmonic Currents and Torque Ripples of Five-Phase Permanent Magnet Synchronous Motors', IEEE Transactions on Industrial Electronics, vol. 66, no. 8, pp. 5820-5829.
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© 1982-2012 IEEE. Five-phase permanent magnet synchronous motors offer merits of high fault tolerant capability and high torque per rms ampere and, thus, are suitable for applications, such as aerospace and electric vehicles. However, the complex machine model causes difficulties in controller design. Besides, having 32 voltage vectors with various effects on currents and torque, the selection of the optimal switching state becomes a challenge to achieve a performance tradeoff. This paper proposes an improved model predictive direct torque control (MPDTC) strategy consisting of a quadratic evaluation method (QEM) and a harmonic voltage elimination method (HVEM). In QEM, the preliminary vector is first chosen from the vectors of the outer decagon according to a cost function for torque and flux regulation. This preliminary vector, composed of three sets of different amplitudes, is further synthesized according to the error between the actual torque/flux and the references. In this way, the optimal voltage vector can be obtained without significantly increasing the computational burden. In HVEM, by subtracting the harmonics voltage component from the vector determined previously in QEM, the final voltage vector is obtained for mitigating stator harmonic currents. The proposed control strategy is compared with the conventional MPDTC approach. The results confirm the effectiveness of the proposed methods with good steady-state performance while maintaining quick dynamic responses.

Li, J, Li, Q & Zhu, J 2019, 'Health condition assessment of wind turbine generators based on supervisory control and data acquisition data', IET Renewable Power Generation, vol. 13, no. 8, pp. 1343-1350.
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Li, N, Zhu, J, Lin, M, Yang, G, Kong, Y & Hao, L 2019, 'Analysis of Axial Field Flux-Switching Memory Machine Based on 3-D Magnetic Equivalent Circuit Network Considering Magnetic Hysteresis', IEEE Transactions on Magnetics, vol. 55, no. 6, pp. 1-4.
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Li, P, Guo, X, Wang, S, Zang, R, Li, X, Man, Z, Li, P, Liu, S, Wu, Y & Wang, G 2019, 'Two-dimensional Sb@TiO_2−x nanoplates as a high-performance anode material for sodium-ion batteries', Journal of Materials Chemistry A, vol. 7, no. 6, pp. 2553-2559.
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Two-dimensional Sb@TiO_2−x nanoplates with abundant voids deliver high reversible capacity, excellent rate capability and stable cycling performance.

Li, T, Xu, J, Wang, C, Wu, W, Su, D & Wang, G 2019, 'The latest advances in the critical factors (positive electrode, electrolytes, separators) for sodium-sulfur battery', Journal of Alloys and Compounds, vol. 792, pp. 797-817.
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© 2019 The sodium-sulfur (Na/S) batteries have caused widespread concern owing to the advantages of low cost and high energy density, these advantages make them promising in the large-scale energy storage system. But the research progress in this field is still at the beginning stage and confronts with tough challenges, for example, the low sulfur conductivity and polysulfide shuttle effect. Considering Na/S battery is a complicated system whose reaction mechanism between sulfur and sodium is different from the operating temperatures, positive electrode hosts and electrolytes, thus a comprehensive understanding about the electrochemistry of the Na/S batteries that operating in high-temperature, intermediate-temperature and room-temperature is necessary. In addition, the critical factors (positive electrodes, electrolytes, separators) associated with the development of high energy density and high performance Na/S battery, it also need to be analysed for the successful application in the near future. In this review, the working methods of high-temperature Na/S (HT-Na/S) battery, intermediate-temperature Na/S (IT-Na/S) battery and room-temperature Na/S (RT-Na/S) battery will be compared, and also focus on the latest progress of positive electrodes, electrolytes and separators in Na/S batteries. Finally, we provide an outlook on the state of the art for the production of more efficient and reliable Na/S batteries with rational technique.

Li, W, Li, J, Liu, Y, Qu, J, Liu, B, Zhu, M, Li, Y, Huang, Z & Zheng, R 2019, 'Artificial 2D Flux Pinning Centers in MgB₂ Induced by Graphitic-Carbon Nitride Coated on Boron for Superconductor Applications', ACS Applied Nano Materials, vol. 2, no. 9, pp. 5399-5408.
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© 2019 American Chemical Society. Systemic investigation was carried out on the microstructure, superconducting properties, and flux pinning mechanism of MgB2 in situ fabricated with magnesium and g-C3N4 coated boron as precursors. The encapsulation of the boron powders with g-C3N4 was achieved by polycondensation of urea on boron powders. The g-C3N4 decomposes during the MgB2 fabrication to induce two-dimensional few-carbon layer, dispersed nanoparticles, and carbon-rich phases in the matrix to enhance the flux pinning force and Hirr of MgB2, which accounts for the in-field critical current density (Jc(H)) increase compared to the pure MgB2. The carbon layers acting as artificial two-dimensional flux pinning centers, have demonstrated high flux pinning efficiency to increase the Jc(H) of MgB2 superconductors.

Li, X, Wang, S, Tang, X, Zang, R, Li, P, Li, P, Man, Z, Li, C, Liu, S, Wu, Y & Wang, G 2019, 'Porous Na3V2(PO4)3/C nanoplates for high-performance sodium storage', Journal of Colloid and Interface Science, vol. 539, pp. 168-174.
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© 2018 Sodium super-ionic conductor (NASICON) structured Na3V2(PO4)3 (NVP), a promising cathode material for sodium-ion batteries (SIBs), benefits by its unique three-dimensional (3D) channel structure. However, the inherent characteristics of NVP (such as low electrical conductivity) usually lead to inferior rate and long-cycling performance, which miss the requirements of practical application in electrical energy storage systems (ESSs). Herein, we propose the synthesis of porous high-crystalline Na3V2(PO4)3/C nanoplates (NVP/C-P) via hydrothermal method and post-calcination. The porous nanoplate structure provides increased specific surface area and shortened diffusion pathway for ion/electron transport. Consequently, NVP/C-P cathodes exhibit a high specific capacity (117 mAh g−1, 0.2 C), exceptional rate performance (76.5 mAh g−1, 100 C) and long cyclic stability (10,000 cycles).

Liang, J, Mondal, AK, Wang, D & Iacopi, F 2019, 'Graphene‐Based Planar Microsupercapacitors: Recent Advances and Future Challenges', Advanced Materials Technologies, vol. 4, no. 1, pp. 1800200-1800200.
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AbstractThe continuous development of integrated electronics such as maintenance‐free biosensors, remote and mobile environmental sensors, wearable personal electronics, nanorobotics etc. and their continued miniaturization has led to an increasing demand for miniaturized energy storage units. Microsupercapacitors with graphene electrodes hold great promise as miniaturized, integrated power sources thanks to their fast charge/discharge rates, superior power performance, and long cycling stability. In addition, planar interdigitated electrodes also have the capability to reduce ion diffusion distances leading to a greatly improved electrochemical performance. Either as standalone power sources or complementing energy harvesting units, it is expected that graphene‐based microsupercapacitors will play a key role as miniaturized power sources in electronic microsystems. This review highlights the recent development, challenges, and perspectives in this area, with an emphasis on the link between material and geometry design of planar graphene‐based electrodes and their electrochemical performance and integrability.

Liu, F, Nattestad, A, Naficy, S, Han, R, Casillas, G, Angeloski, A, Sun, X & Huang, Z 2019, 'Fluorescent Carbon‐ and Oxygen‐Doped Hexagonal Boron Nitride Powders as Printing Ink for Anticounterfeit Applications', Advanced Optical Materials, vol. 7, no. 24, pp. 1901380-1901380.
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AbstractIncreasing demands for optical anticounterfeiting technology require the development of versatile luminescent materials with tunable photoluminescence properties. Herein, a number of fluorescent carbon‐ and oxygen‐doped hexagonal boron nitride (denoted as BCNO) phosphors are found to offer a such high‐tech anticounterfeiting solution. These multicolor BCNO powders, developed in a two‐step process with controlled annealing and oxidation, feature rod‐like particle shape, with varied luminescence properties. Studies of the optical properties of BCNO, along with other characterization, provide insight into this underexplored material. Anticounterfeiting applications are demonstrated with printed patterns which are indistinguishable to the naked eye under visible light but become highly discernible under UV irradiation. The fabricated patterns are demonstrated to be both chemically stable in corrosive environments and physically robust in mechanical bending testing. These properties render BCNO as promising and versatile anticounterfeiting material a wide variety of environments.

Liu, Y, Xu, W, Zhu, J & Blaabjerg, F 2019, 'Sensorless Control of Standalone Brushless Doubly Fed Induction Generator Feeding Unbalanced Loads in a Ship Shaft Power Generation System', IEEE Transactions on Industrial Electronics, vol. 66, no. 1, pp. 739-749.
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© 1982-2012 IEEE. The standalone brushless doubly fed induction generator (BDFIG) has demonstrated excellent energy-saving performance in ship shaft power generation applications. As a standalone system, it exhibits unbalanced terminal voltages and poor performance under unbalanced loads. However, the existing control scheme of grid-connected BDFIGs cannot be directly applied to stabilize the amplitude and frequency of terminal voltage when the rotor speed and electrical load vary. This paper presents a new sensorless control scheme for the standalone BDFIG under unbalanced load conditions in the ship shaft power generation system. A second-order generalized integrator-based quadrature signal generator is introduced to realize the rotor speed observer for the standalone BDFIG feeding unbalanced loads. The compensation method of negative-sequence power winding voltage is proposed to eliminate the negative-sequence component of the unbalanced power winding voltage. Comprehensive experiments are carried out on a prototype BDFIG with and without the compensation of negative-sequence power winding voltage. The good performance of the proposed sensorless control scheme is verified by the experimental test results.

Luo, C-Q, Ling, FC-C, Rahman, MA, Phillips, M, Ton-That, C, Liao, C, Shih, K, Lin, J, Tam, HW, Djurišić, AB & Wang, S-P 2019, 'Surface polarity control in ZnO films deposited by pulsed laser deposition', Applied Surface Science, vol. 483, pp. 1129-1135.
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© 2019 Elsevier B.V. We demonstrate a simple and inexpensive method of surface polarity control of ZnO grown by pulsed laser deposition (PLD). The polarity control is achieved in a straightforward way by changing the thickness of MgO buffer layer. The Zn- and O-polar ZnO films possess very distinct growth rate, electron concentration and mobility as well as different defect structures. These different structural and electronic properties result in significant differences in surface reactivity and device performance. For example, Pd Schottky diodes fabricated onto the O-polar ZnO film exhibit lower barrier height and ideality factor compared with the equivalent Zn-polar devices, while methylammonium lead iodide perovskite films are readily formed on O-terminated and rapidly decompose on Zn-terminated surfaces. This can be attributed to higher photocatalytic activity of Zn-terminated surface, as well as higher surface coverage of adsorbed hydroxyl groups. Consequently, our results indicate that polarity engineering to obtain favorable O-terminated surface can result in improved performance of ZnO-containing optoelectronic devices, while Zn-terminated surfaces could be of interest for photocatalytic and sensing applications.

Ma, B, Huang, Y, Nie, Z, Qiu, X, Su, D, Wang, G, Yuan, J, Xie, X & Wu, Z 2019, 'Facile synthesis of Camellia oleifera shell-derived hard carbon as an anode material for lithium-ion batteries', RSC Advances, vol. 9, no. 35, pp. 20424-20431.
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Bio-waste Camellia oleifera shells (COS) are converted into porous carbon by a two-step method.

Mahmood, A, Li, S, Ali, Z, Tabassum, H, Zhu, B, Liang, Z, Meng, W, Aftab, W, Guo, W, Zhang, H, Yousaf, M, Gao, S, Zou, R & Zhao, Y 2019, 'Ultrafast Sodium/Potassium‐Ion Intercalation into Hierarchically Porous Thin Carbon Shells', Advanced Materials, vol. 31, no. 2, pp. 1805430-1805430.
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AbstractThe large‐scale application of sodium/potassium‐ion batteries is severely limited by the low and slow charge storage dynamics of electrode materials. The crystalline carbons exhibit poor insertion capability of large Na+/K+ ions, which limits the storage capability of Na/K batteries. Herein, porous S and N co‐doped thin carbon (S/N@C) with shell‐like (shell size ≈20–30 nm, shell wall ≈8–10 nm) morphology for enhanced Na+/K+ storage is presented. Thanks to the hollow structure and thin shell‐wall, S/N@C exhibits an excellent Na+/K+ storage capability with fast mass transport at higher current densities, leading to limited compromise over charge storage at high charge/discharge rates. The S/N@C delivers a high reversible capacity of 448 mAh g‐1 for Na battery, at the current density of 100 mA g‐1 and maintains a discharge capacity up to 337 mAh g‐1 at 1000 mA g‐1. Owing to shortened diffusion pathways, S/N@C delivers an unprecedented discharge capacity of 204 and 169 mAh g‐1 at extremely high current densities of 16 000 and 32 000 mA g‐1, respectively, with excellent reversible capacity for 4500 cycles. Moreover, S/N@C exhibits high K+ storage capability (320 mAh g‐1 at current density of 50 mA g‐1) and excellent cyclic life.

Malekjamshidi, Z, Jafari, M, Zhu, J & Xiao, D 2019, 'Comparative Analysis of Input Power Factor Control Techniques in Matrix Converters Based on Model Predictive and Space Vector Control Schemes', IEEE Access, vol. 7, pp. 139150-139160.
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Model Predictive Control (MPC) with a finite control set and space vector modulation (SVM) are the most common control methods for the matrix converters (MCs). This paper is focused on the input and output currents performance analysis of the matrix converter controlled by SVM and MPC. A closed-loop control of the input current displacement angle is employed in the SVM strategy to provide unity input power factor over a wide range of voltage transfer ratio. For MPC, a discrete-time model of the converter, including the input filter and load, are used to predict the input and output currents for each valid switching state. The MPC, SVM, and power factor controlled SVM (PFC-SVM) methods are analyzed in detail, and their performance in controlling the input power factor, current quality, and transient response are compared through numerical simulations and experimental tests.

Malekjamshidi, Z, Jafari, M, Zhu, J & Xiao, D 2019, 'Comparison of matrix converter stabilisation techniques based on the damping resistor and digital filter approaches for bidirectional power flow control', IET Power Electronics, vol. 12, no. 15, pp. 3964-3976.
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The matrix converter is becoming a mature technology with its specific advantages and limitations, and can be effectively used as an interface link in the future smart grids. In this context, the stability of the converter under different power flow conditions is highly important and needs more clarification. The input inductor-capacitor filter can significantly impact the stability of the converter when the output is tightly regulated, especially in bidirectional power flow control applications where a low-impedance source is connected to the converter output. This paper investigates the matrix converter stability for bidirectional power flow control, considering the input filter and other parameters of the system. A detailed analysis of two commonly used active and passive stabilization techniques known as digital filter and damping resistor approaches is presented, and a third method based on a combination of these two methods is suggested in this paper. The converter stability region for the proposed technique is determined by using the small-signal model of the converter. The converter performance for the methods is compared in terms of the efficiency, stability, transients and quality of the input and output currents. Numerical simulations and experimental tests are conducted on a prototype direct matrix converter to validate the proposed method.

Man, Z, Li, P, Zhou, D, Zang, R, Wang, S, Li, P, Liu, S, Li, X, Wu, Y, Liang, X & Wang, G 2019, 'High-performance lithium–organic batteries by achieving 16 lithium storage in poly(imine-anthraquinone)', Journal of Materials Chemistry A, vol. 7, no. 5, pp. 2368-2375.
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The Li/PIAQ cell exhibits excellent electrochemical performances with a 16 Li-storage mechanism based on DFT calculations and experimental investigations.

Maniam, S, Higginbotham, HF, Bell, TDM & Langford, SJ 2019, 'Frontispiece: Harnessing Brightness in Naphthalene Diimides', Chemistry – A European Journal, vol. 25, no. 29.
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Maniam, S, Higginbotham, HF, Bell, TDM & Langford, SJ 2019, 'Harnessing Brightness in Naphthalene Diimides', Chemistry – A European Journal, vol. 25, no. 29, pp. 7044-7057.
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AbstractThe development of brightly emissive compounds is of great research and commercial interest, with established and emerging applications across chemistry, biology, physics, medicine and engineering. Among the many types of molecules available, naphthalene diimides have been widely used for both fundamental photophysical studies and in practical applications that utilise fluorescence as an information readout. The monomeric naphthalene diimide is weakly fluorescent, however through various methods of core‐derivatisation, it can be developed to be highly fluorescent and further functionalised to add utility. In this review, we highlight recent advances made in naphthalene diimide chemistry that have led to development of molecules with improved optical properties, and the design strategies utilised to produce bright fluorescence emission as small molecules or in supramolecular architectures.

Mishra, N, Bosi, M, Rossi, F, Salviati, G, Boeckl, J & Iacopi, F 2019, 'Growth of graphitic carbon layers around silicon carbide nanowires', Journal of Applied Physics, vol. 126, no. 6, pp. 065304-065304.
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We demonstrate the ability to synthesize graphitic carbon sheets around cubic silicon carbide nanowires via an alloy-mediated catalytic process. The transmission electron microscopy analysis shows multilayer graphitic carbon sheets with a large interatomic layer distance of ∼0.45 nm, suggesting the presence of oxygen in the graphitic system. Oxygen-related peaks observed by energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy further confirm the oxidation of the graphitic carbon layers. A detailed investigation of the Raman spectra reveals a turbostratic stacking of the graphitic carbon layers. The turbostratic nature and the presence of oxidation in the graphitic carbon surrounding the silicon carbide nanowires make them a suitable platform for further functionalization, of particular interest for biosensing, as both graphitic carbon and silicon carbide are biocompatible.

Praikaew, P, Maniam, S, Charoenpanich, A, Sirirak, J, Promarak, V, Langford, SJ & Wanichacheva, N 2019, 'Water-soluble Cu2+-fluorescent sensor based on core-substituted naphthalene diimide and its application in drinking water analysis and live cell imaging', Journal of Photochemistry and Photobiology A: Chemistry, vol. 382, pp. 111852-111852.
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Water-soluble naphthalene diimide based fluorescent chemosensor, N1, was designed for Cu2+ recognition. The sensor exhibited significant fluorescence modulation and chromogenic change with high Cu2+ sensitivity and selectivity over interfering metal ions. The sensor was able to efficiently monitor Cu2+ in 100% aqueous buffer solution with a low detection limit of 0.7 ppb which is much lower than the recommended value in drinking water by the United States Environmental Protection Agency (U.S. EPA) and the World Health Organization (WHO). The complex formation of N1 with Cu2+ was found to be 1:1 N1-Cu2+ by Job's plot analysis. Furthermore, the sensor was highly tolerant to interference from a matrix of real samples such as drinking water and human liver carcinoma cell line.

Rahman, MA, Islam, MR, Muttaqi, KM, Guo, Y, Zhu, J, Sutanto, D & Lei, G 2019, 'A Modified Carrier-Based Advanced Modulation Technique for Improved Switching Performance of Magnetic-Linked Medium-Voltage Converters', IEEE Transactions on Industry Applications, vol. 55, no. 2, pp. 2088-2098.
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© 1972-2012 IEEE. The high-frequency magnetic link is gaining popularity due to its lightweight, small volume, and inherent voltage balancing capability. Those features can simplify the utilization of a multilevel converter (MLC) for the integration of renewable energy sources to the grid with compact size and exert economic feasibility. The modulation and control of the MLC are crucial issues, especially for grid-connected applications. To support the grid, the converter may need to operate in an overmodulation (OVM) region for short periods depending upon the loading conditions. This OVM operation of the converter causes increased harmonic losses and adverse effects on the overall system efficiency. On top of that, the size and cost of filtering circuitry become critical to eliminate the unwanted harmonics. In this regard, a modified OVM scheme with phase-disposed carriers for a grid-connected high-frequency magnetic-link-based cascaded H-bridge (CHB) MLC is proposed for the suppression of harmonics and the reduction of converter loss. Furthermore, with the proposed OVM technique, the voltage gain with the modulation index can be increased up to the range which is unlikely to be achieved using the classical ones. Extensive simulations are carried out with a 2.24 MVA permanent magnet synchronous generator based wind energy conversion system, which is connected to the 11 kV ac grid through a high-frequency magnetic-link and a five-level CHB MLC. A scaled down laboratory prototype is implemented to validate the performance of the converter.

Sarker, PC, Islam, MR, Guo, Y, Zhu, J & Lu, HY 2019, 'State-of-the-Art Technologies for Development of High Frequency Transformers with Advanced Magnetic Materials', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2, pp. 1-11.
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© 2002-2011 IEEE. With the development of advanced soft magnetic materials of high-saturation flux density and low specific core loss and semiconductor power devices, the high-frequency transformer (HFT) has received significant attention in recent years for its widespread emerging applications. The optimal design of high-power-density HFTs for high-performance energy conversion systems is, however, a multiphasic problem that needs special considerations on various aspects such as core material selection, minimization of parasitic components, and thermal management. This paper presents a comprehensive review on advancement of soft magnetic materials for high-power-density magnetic devices and advanced technologies for characterizations and optimal design of HFTs. The future research and development trends are also discussed.

Shahcheraghi, N, Gentle, A, Supansomboon, S, Keast, V & Cortie, MB 2019, 'Localized surface plasmons in platinum aluminide semi-shells', Nano Futures, vol. 3, no. 1, pp. 015003-015003.
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© 2019 IOP Publishing Ltd. The dielectric function of the intermetallic compound PtAl2 is assessed and found to be comparable to that of titanium nitride, suggesting that nanostructures of PtAl2 may be suitable for plasmonic devices. In order to probe this further, the optical properties of experimentally produced arrays of nanoscale PtAl2 semi-shells of about 300 nm diameter were examined and compared to the results of numerical simulations. The structures showed a broad localized surface plasmon resonance centered on ∼1.3 eV (∼950 nm), which matched the simulations. Calculations showed that a ten-fold enhancement of the electric field of the incident light will be achieved around the rim of suitably oriented PtAl2 semi-shells. The phase of the oscillation induced by 1060 nm light will be retarded by π/2 relative to the incident light. This is indicative of a resonant condition. These observations suggest that it could be worthwhile to investigate possible applications for this and other intermetallic compounds in nanoscale plasmonic devices.

Sharif, HMA, Mahmood, A, Cheng, H-Y, Djellabi, R, Ali, J, Jiang, W-L, Wang, S-S, Haider, MR, Mahmood, N & Wang, A-J 2019, 'Fe₃O₄ Nanoparticles Coated with EDTA and Ag Nanoparticles for the Catalytic Reduction of Organic Dyes from Wastewater', ACS Applied Nano Materials, vol. 2, no. 8, pp. 5310-5319.
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Shi, X, Zhu, J, Li, L, Lu, DD-C, Zhang, J & Yang, H 2019, 'Predictive Duty Cycle Control With Reversible Vector Selection for Three-Phase AC/DC Converters', IEEE Transactions on Power Electronics, vol. 34, no. 5, pp. 4868-4882.
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© 2018 IEEE. The conventional predictive duty cycle control (CPDCC) of three-phase full-bridge ac/dc converters selects adjacent nonzero vector pair based on the grid-voltage vector location, then the duration for each vector is calculated. Though the vector selection method is quite simple, it has a significant disadvantage that the values of calculated durations could be frequently less than zero due to nonoptimal vector selection, which results in high current harmonics and power notches. It could be improved with improved predictive duty cycle control (IPDCC) by reselecting the nonzero vector pair when negative duration exists; however, the whole vector selection and calculation procedure are repeated. By theoretical verification that the power variation rates of reversible vector pair are symmetrical with respect to that of zero vector, this paper proposes the reversible predictive duty cycle control (RPDCC) simply by replacing the original vector with its opposite vector and the recalculation of vector duration is eliminated compared with IPDCC. Thus, the calculation effort is almost not increased compared with CPDCC while system performance is significantly improved. The proposed control is theoretically derived and verified with the simulation and experimental results showing that RPDCC has better steady and dynamic performance than CPDCC and IPDCC methods.

Shi, Z, Sun, X, Cai, Y, Yang, Z, Lei, G, Guo, Y & Zhu, J 2019, 'Torque Analysis and Dynamic Performance Improvement of a PMSM for EVs by Skew Angle Optimization', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2, pp. 1-5.
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© 2018 IEEE. In this paper, a permanent magnet synchronous machine (PMSM) for electric vehicles (EVs) is studied. Since EVs need to face some low speed road conditions, it is necessary to drive the machine to maintain a stable torque at low speed. The stator skew slot is often adopted to reduce torque ripple; however, it declines the output torque at same time. Besides, the difference between positive rotation performance and negative rotation performance, which caused by the skew slot are often ignored. Through the finite element analysis, the cogging torque and dynamic performance of the PMSM at different skew angle are studied. Moreover, the different influence of slot skew angle on positive and negative rotation performance is studied. Then, the optimum skew angle of the PMSM is studied through comprehensive consideration. Finally, the cogging torque of the prototype is verified to be less than 2 N·m through the experiment.

Sillapachaiyaporn, C, Nilkhet, S, Ung, AT & Chuchawankul, S 2019, 'Anti-HIV-1 protease activity of the crude extracts and isolated compounds from Auricularia polytricha', BMC Complementary and Alternative Medicine, vol. 19, no. 1.
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Abstract Background Acquired immunodeficiency syndrome (AIDS) is caused by the Human immunodeficiency virus type-1 (HIV-1). HIV-1 protease (HIV-1 PR) is an essential enzyme for the HIV replication, and therefore, it is an important target for antiretroviral drugs development, particularly from natural products. Auricularia polytricha (AP) is an edible mushroom with several important therapeutic properties. These properties will be investigated as HIV-1 PR inhibitors. Methods The sequential hexane (APH), ethanol (APE) and water (APW) extracts from AP were screened for inhibitory activity against HIV-1 PR. The extract that consistently showed the strong HIV-1 PR inhibition was further investigated for its phytochemical constituents. The compounds were purified by column chromatography. The isolated compounds were structurally elucidated using 1D and 2D NMR, HRMS, FTIR, and GC/MS techniques. Each compound was screened against HIV-1 PR to determine its inhibitory activity and to provide an explanation for the activity found in the extract. Results Hexane crude extract of AP (APH) exhibited significant inhibition on HIV-1 PR activity. Four major compounds isolated from APH fraction were identified to be two triacylglycerols, linoleic acid and ergosterol. Moreover, all four compounds showed significant inhibition of HIV-1 PR activity. Conclusion The findings from this study suggest that AP is a good source of fatty esters, fatty acids and ergosterol. These natural products exhibit anti-HIV-1 properties by block...

Song, J, Guo, X, Zhang, J, Chen, Y, Zhang, C, Luo, L, Wang, F & Wang, G 2019, 'Rational design of free-standing 3D porous MXene/rGO hybrid aerogels as polysulfide reservoirs for high-energy lithium–sulfur batteries', Journal of Materials Chemistry A, vol. 7, no. 11, pp. 6507-6513.
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A Ti₃C₂T_x MXene/rGO hybrid aerogel is applied for the first time as a free-standing polysulfide reservoir to inhibit the shuttle effect and improve the overall performance of Li–S batteries.

Sun, X, Diao, K, Lei, G, Guo, Y & Zhu, J 2019, 'Study on Segmented-Rotor Switched Reluctance Motors With Different Rotor Pole Numbers for BSG System of Hybrid Electric Vehicles', IEEE Transactions on Vehicular Technology, vol. 68, no. 6, pp. 5537-5547.
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© 1967-2012 IEEE. This paper investigates the design principles and performance optimization for segmented-rotor switched reluctance motors (SRSRMs) with different rotor pole numbers for belt-driven starter generators of hybrid electric vehicles. For the design principles, several constraints are derived for the numbers of stator and rotor poles, the dimensions, and the number of winding turns. Two SRSRMs with 16/10 and 16/14 stator/rotor poles are presented according to these principles. For the performance optimization, the two motors are optimized individually for maximizing the torque. To evaluate the effect of different segmented-rotor numbers, the overall performances of the two SRSRMs are investigated and compared. It is found that the 16/14 SRSRM has higher flux linkage and static torque. The 16/14 SRSRM exhibits higher torque and lower torque ripple at low speed operation, whereas at high speed, the 16/10 SRSRM performs better in terms of torque and power densities. Compared with the 16/14 SRSRM, the 16/10 SRSRM has higher final steady speed under the same startup condition. The 16/10 SRSRM can achieve higher steady speed under starter mode and provide higher generated power under braking mode. Moreover, the 16/10 SRSRM exhibits higher efficiency in the most feasible speed range, especially in high speed range, and it has wider high-efficiency area. Finally, a 16/10 SRSRM is prototyped and tested to validate the simulation results.

Sun, X, Hu, C, Zhu, J, Wang, S, Zhou, W, Yang, Z, Lei, G, Li, K, Zhu, B & Guo, Y 2019, 'MPTC for PMSMs of EVs With Multi-Motor Driven System Considering Optimal Energy Allocation', IEEE Transactions on Magnetics, vol. 55, no. 7, pp. 1-6.
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© 1965-2012 IEEE. This paper presents a compound propulsion system with a high-speed permanent-magnet synchronous motor (PMSM) and two in-wheel motors for electric vehicles (EVs). In this paper, the longitudinal dynamic model of EVs is first presented. Then traction distribution ratio \alpha is introduced to express the traction distribution between the front and the rear axles. Moreover, the function of power consumption concerned with the traction distribution ratio \alpha is established. Therefore, the \alpha that minimizes the power consumption function is selected as the optimal traction distribution ratio. To improve the performance of motor controllers, the model predictive torque control (MPTC) method is employed for high-speed and in-wheel motor drives. Experimental comparison with field-oriented control (FOC) shows the advantages of MPTC in dynamic response. Finally, experimental comparisons and hardware-in-loop (HiL) tests are presented to verify the MPTC method and the proposed energy allocation method, respectively.

Sun, X, Shi, Z, Lei, G, Guo, Y & Zhu, J 2019, 'Analysis and Design Optimization of a Permanent Magnet Synchronous Motor for a Campus Patrol Electric Vehicle', IEEE Transactions on Vehicular Technology, vol. 68, no. 11, pp. 10535-10544.
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© 1967-2012 IEEE. This work presents the analysis, design and optimization of a permanent magnet synchronous motor (PMSM) for an electric vehicle (EV) used for campus patrol with a specific drive cycle. Firstly, based on the collected data like the parameters and speed from a test EV on the campus road, the dynamic calculation of the EV is conducted to decide the rated power and speed range of the drive PMSM. Secondly, according to these requirements, an initial design and some basic design parameters are obtained. Thirdly, optimization process is implemented to improve the performance of the designed PMSM. The permanent magnet (PM) structure, airgap length and stator core geometry are optimized respectively in this step. Different optimization processes are proposed to meet multiple optimization objectives simultaneously. Based on the finite element analysis (FEA) method, it is found that the harmonic of the optimized PMSM is lower than that of the initial design, and the torque ripple is reduced by 24%. The effectiveness of optimization on the core loss and PM eddy loss is validated and the temperature rise is suppressed effectively. Finally, a prototype is fabricated for the optimized PMSM and an experimental platform is developed. The test results verify that the optimized PMSM meets the requirements of the specific campus patrol EV well.

Teng, QF, Cui, HW, Zhu, JG, Guo, YG & Tian, J 2019, 'Current sensorless-based model predictive control for PMSM drive system', Dianji yu Kongzhi Xuebao/Electric Machines and Control, vol. 23, no. 5, pp. 119-128.
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Based on extended state observer (ESO), a novel model predictive torque control (MPTC) strategy was developed for three phase permanent magnet synchronous motor (PMSM) drive system with current sensorless. To achieve high precision control, generally two phase current sensors are indispensable for successful operation of the feedback control. For this purpose, by use of technique of ESO, a new observer for estimating three phase currents and time-varying stator resistance was put forward. Moreover, to reduce torque and flux ripples and improve the performance of the torque and speed, MPTC strategy was employed. The resultant ESO-based MPTC strategy enables PMSM drive system not only to run stably and reliably but also to have satisfactory control performance and strong robustness. The simulation results validate the feasibility and effectiveness of the proposed scheme.

Tian, H, Liang, J & Liu, J 2019, 'Nanoengineering Carbon Spheres as Nanoreactors for Sustainable Energy Applications', Advanced Materials, vol. 31, no. 50, pp. 1903886-1903886.
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AbstractColloidal carbon sphere nanoreactors have been explored extensively as a class of versatile materials for various applications in energy storage, electrochemical conversion, and catalysis, due to their unique properties such as excellent electrical conductivity, high specific surface area, controlled porosity and permeability, and surface functionality. Here, the latest updated research on colloidal carbon sphere nanoreactor, in terms of both their synthesis and applications, is summarized. Various synthetic strategies are first discussed, including the hard template method, the soft template method, hydrothermal carbonization, the microemulsion polymerization method, and extension of the Stöber method. Then, the functionalization of colloidal carbon sphere nanoreactors, including the nanoengineering of compositions and the surface features, is discussed. Afterward, recent progress in the major applications of colloidal carbon sphere nanoreactors, in the areas of energy storage, electrochemical conversion, and catalysis, is presented. Finally, the perspectives and challenges for future developments are discussed in terms of controlled synthesis and functionalization of the colloidal carbon sphere nanoreactors with tunable structure, and the composition and properties that are desirable for practical applications.

Tian, H, Liu, X, Dong, L, Ren, X, Liu, H, Price, CAH, Li, Y, Wang, G, Yang, Q & Liu, J 2019, 'Enhanced Hydrogenation Performance over Hollow Structured Co‐CoOx@N‐C Capsules', Advanced Science, vol. 6, no. 22, pp. 1900807-1900807.
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AbstractIt is desirable to design nonprecious metal nanocatalysts with high stability and catalytic performance for fine chemicals production. Here, a method is reported for the preparation of cobalt metal and cobalt oxide cores confined within nanoporous nitrogen‐doped hollow carbon capsules. Core–shell structured Zn/Co‐ZIF@polymer materials are fabricated through a facile coating polymer strategy on the surface of zeolitic imidazolate frameworks (ZIF). A series of hollow carbon capsules with cobalt metal and cobalt oxide are derived from a facile confined pyrolysis of Zn/Co‐ZIF@polymer. The hollow Co‐CoOx@N‐C capsules can prevent sintering and agglomeration of the cobalt nanoparticles and the nanoporous shell allows for efficient mass transport. The specific surface area and Co particle size are optimized through finely tuning the original Zn content in ZIF particles, thus enhancing overall catalytic activity. The yolk–shell structured Zn4Co1Ox@carbon hollow capsules are shown to be a highly active and selective catalyst (selectivity >99%) for hydrogenation of nitrobenzene to aniline. Furthermore, Zn4Co1Ox@carbon hollow particles show superior catalytic stability, and no deactivation after 8 cycles of reaction. The hollow Co‐CoOx@N‐C capsules may shed light on a green and sustainable catalytic process for fine chemicals production.

Tian, H, Shao, H, Chen, Y, Fang, X, Xiong, P, Sun, B, Notten, PHL & Wang, G 2019, 'Ultra-stable sodium metal-iodine batteries enabled by an in-situ solid electrolyte interphase', Nano Energy, vol. 57, pp. 692-702.
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© 2018 Elsevier Ltd High capacity sodium (Na) metal anodes open up new opportunities for developing next-generation rechargeable batteries with both high power and high energy densities. However, many challenges still plagued their practical application, including low plating/stripping Coulombic efficiency (CE) and dendrite growth after repeated cycle inducing safety issue. Especially, the sodium metal is less stable in organic (i.e. carbonate-based) electrolytes than lithium metal, due to the more unstable organic solid–electrolyte interface (SEI). Herein, we report a facile technology to stabilize sodium metal anode and inhibit the growth of sodium dendrites. The in-situ ultrathin NaI SEI layer successfully endows best-performance Na/I 2 metal batteries (>2200 cycles) with high capacity (210 mA h g −1 at 0.5 C) based on the conversion reaction chemistry with higher discharge voltage plateau (> 2.7 V) and lower overpotential (134 mV) due to the fast charge transfer dynamics and interfacial stability compared with pristine Na anode. The detailed theoretical calculations and experimental results elucidate that NaI layer has a much lower diffusion barrier compared to that of NaF (NaF as one the most commonly found inorganic components in Na-based SEI layer), and actually facilitates more uniform sodium deposition. This work provides a new avenue for designing low-cost, high-performance and high-safety sodium metal-iodine batteries and other metal-iodine batteries.

Tian, H, Yu, X, Shao, H, Dong, L, Chen, Y, Fang, X, Wang, C, Han, W & Wang, G 2019, 'Unlocking Few‐Layered Ternary Chalcogenides for High‐Performance Potassium‐Ion Storage', Advanced Energy Materials, vol. 9, no. 29, pp. 1901560-1901560.
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AbstractPotassium‐ion batteries (KIBs) have attracted increasing attention for grid‐scale energy storage due to the abundance of potassium resources, low cost, and competitive energy density. The key challenge for KIBs is to develop high‐performance electrode materials. However, the exploration of high‐capacity and ultrastable electrodes for KIBs remains challenging because of the sluggish diffusion kinetics of K+ ions during the charging/discharging processes. This study reports for the first time a facile ion‐intercalation‐mediated exfoliation method with Mg2+ cations and NO3– anions as ion assistants for the fabrication of expanded few‐layered ternary Ta2NiSe5 (EF‐TNS) flakes with interlayer spacing up to 1.1 nm and abundant Se sites (NiSe4 tetrahedra/TaSe6 octahedra clusters) for superior potassium‐ion storage. The EF‐TNS deliver a high capacity of 315 mAh g–1, excellent rate capability (121 mAh g–1 at a current density of 1000 mA g–1), and ultrastable cycling performance (81.4% capacity retention after 1100 cycles). Detailed theoretical analysis via first‐principles calculations and experimental results elucidate that K+ ions intercalate through the expanded interlayers effectively and prefer to transport along zigzag pathways in layered Ta2NiSe5. This work provides a new avenue for designing novel ternary intercalation/pseudocapacitance‐type KIBs with high capacity, excellent rate capability, and superior long‐term cycling performance.

Wang, C, Zhang, L, Al‐Mamun, M, Dou, Y, Liu, P, Su, D, Wang, G, Zhang, S, Wang, D & Zhao, H 2019, 'A Hollow‐Shell Structured V₂O₅ Electrode‐Based Symmetric Full Li‐Ion Battery with Highest Capacity', Advanced Energy Materials, vol. 9, no. 31, pp. 1900909-1900909.
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AbstractThe symmetric batteries with an electrode material possessing dual cathodic and anodic properties are regarded as an ideal battery configuration because of their distinctive advantages over the asymmetric batteries in terms of fabrication process, cost, and safety concerns. However, the development of high‐performance symmetric batteries is highly challenging due to the limited availability of suitable symmetric electrode materials with such properties of highly reversible capacity. Herein, a triple‐hollow‐shell structured V2O5 (THS‐V2O5) symmetric electrode material with a reversible capacity of >400 mAh g−1 between 1.5 and 4.0 V and >600 mAh g−1 between 0.1 and 3.0 V, respectively, when used as the cathode and anode, is reported. The THS‐V2O5 electrodes assembled symmetric full lithium‐ion battery (LIB) exhibits a reversible capacity of ≈290 mAh g−1 between 2 and 4.0 V, the best performed symmetric energy storage systems reported to date. The unique triple‐shell structured electrode makes the symmetric LIB possessing very high initial coulombic efficiency (94.2%), outstanding cycling stability (with 94% capacity retained after 1000 cycles), and excellent rate performance (over 140 mAh g−1 at 1000 mA g−1). The demonstrated approach in this work leaps forward the symmetric LIB performance and paves a way to develop high‐performance symmetric battery electrode materials.

Wang, C, Zhang, L, Al‐Mamun, M, Dou, Y, Liu, P, Su, D, Wang, G, Zhang, S, Wang, D & Zhao, H 2019, 'Lithium Ion Batteries: A Hollow‐Shell Structured V₂O₅ Electrode‐Based Symmetric Full Li‐Ion Battery with Highest Capacity (Adv. Energy Mater. 31/2019)', Advanced Energy Materials, vol. 9, no. 31, pp. 1970120-1970120.
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Wang, J, Su, P, Zhang, J, Wang, F, Chen, Y, Liu, H & Liu, J 2019, 'The formation of yolk–shell structured NiO nanospheres with enhanced lithium storage capacity', Materials Chemistry Frontiers, vol. 3, no. 8, pp. 1619-1625.
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Yolk–shell structured NiO nanospheres were successfully fabricated and showed excellent performance as an anode for lithium-ion batteries.

Wang, S, Liu, C, Wang, Y, Lei, G & Zhu, J 2019, '6σ Robust Multidisciplinary Design Optimization Method for Permanent Magnet Motors with Soft Magnetic Composite Cores', Diangong Jishu Xuebao/Transactions of China Electrotechnical Society, vol. 34, no. 4, pp. 637-645.
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Soft magnetic composite (SMC) is a new kind of magnetic material, which has been widely used in the design of permanent magnet machines due to its unique electromagnetic characteristic. The cores made by SMC are isotropic magnetically and mechanically with lower eddy current loss, and can be manufactured by molded technology. Therefore, this material is promising for the design of motors with complex structure, such as transverse flux machine and claw pole motor. To improve the application of the motors made by SMC, two main research topics need to be investigated. The first one is the multidisciplinary design optimization, which mainly includes the electromagnetic analysis and thermal analysis. The second one is the robust design optimization, which mainly investigates the manufacturing precision/tolerances in the engineering manufacturing process and their effects on motor's performance. The main aim of this work is to present a Six Sigma (6σ) robust design optimization method for SMC motors under the framework of multidisciplinary design optimization. From the discussion, it can be found that the proposed method can improve the motor's performance while keeping the requirements in term of temperature rise conditions. Compared with traditional deterministic design approach, the new method can improve the reliability of the designed motor significantly, which will benefit the batch production of SMC motors in industry.

Wang, S, Wang, Y, Liu, C, Lei, G, Zhu, J & Guo, Y 2019, 'Comparative Study of Linear Superconductivity Machine With Different Stator and Winding Configurations', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2, pp. 1-4.
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© 2002-2011 IEEE. Compared with rotary electrical machines in linear drive applications, linear machines without rotary-linear motion conversion equipment can have higher force density and efficiency. Linear superconductivity machines (LSMs), consisting of high-performance superconducting magnets instead of permanent magnets, can offer very high force density and efficiency compared with other linear machines, such as linear induction machine, linear permanent magnet machine, and so on. In this paper, LSMs with different stators and winding configurations are investigated, specifically LSMs with concentrated or distributed windings, and unilateral or bilateral side stators. The electromagnetic parameters and performance of these LSMs are calculated and compared by using the finite element method, and then, the main difference between various design methods in LSM has been presented.

Wang, Y, Fan, S, Liao, F, Zheng, X, Huang, Z, Wang, Y & Han, X 2019, 'In situ formation and superior lithium storage properties of tentacle-like ZnO@NC@CNTs composites', Nanoscale Advances, vol. 1, no. 3, pp. 1200-1206.
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A novel structure of double carbon coated tentacle-like ZnO composite has been synthesized, which delivers remarkable Li⁺ storage properties.

Wang, Y, Lu, J, Liu, C, Lei, G, Guo, Y & Zhu, J 2019, 'Development of a High-Performance Axial Flux PM Machine With SMC Cores for Electric Vehicle Application', IEEE Transactions on Magnetics, vol. 55, no. 7, pp. 1-4.
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© 1965-2012 IEEE. A new axial flux permanent magnet machine (AFPM) with soft magnetic composited (SMC) cores is proposed for electric vehicle (EV) application in this paper. As its windings are wound on the stator ring core, it can be regarded as a toroidally wound internal stator (TORUS) machine. With the adopted SMC material for stator core, this machine has the benefits of 3-D magnetic flux properties. The windings and SMC cores can be designed to form a very compact structure, and thus, the torque density can be improved greatly. To obtain the a good flux concentrating ability, two TORUS machines are designed and analyzed, one is with NdFeB magnet for high-performance EV application and the other is with the cheap ferrite magnet for low-cost application. The 3-D finite-element method is used to analyze the electromagnetic parameter and performance. For performance comparison, a commercial AFPM with yokeless and segmented armature P400 is used.

Wang, Y, Ma, J, Liu, C, Lei, G, Guo, Y & Zhu, J 2019, 'Reduction of Magnet Eddy Current Loss in PMSM by Using Partial Magnet Segment Method', IEEE Transactions on Magnetics, vol. 55, no. 7, pp. 1-5.
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© 1965-2012 IEEE. Compared with traditional induction machine and direct current machine, permanent magnet synchronous machine (PMSM) holds many merits like higher torque ability and efficiency when high magnetic co-energy sintered NdFeB magnet is used. However, for the operation with high frequency, the resulted eddy current loss by the permanent magnet (PM) is very high and this kind of loss can bring the PM with high-temperature rise, making the PM face the risk of irreversible demagnetization. To reduce the PM eddy current loss, complete magnet segmentation is an effective method. However, taking this kind of method will increase manufacturing cost and reduce the mechanical robustness of the PMSM. Thus, a partial magnet segmentation method was proposed in the past. In this paper, a new annular partial segmentation (APS) method is proposed for the reduction of the PM eddy current loss, including single-side APS and double-side APS configurations. Considering that the additional process on the PM will reduce the mechanical robustness of the PM and the electromagnetic performance of machine, both the electromagnetic performance and the mechanical strength of the PM have been analyzed, based on 3-D finite-element method. It can be found that if the proposed new annular partial segmentation (APS) method is adopted, the eddy current loss in the PM can be reduced greatly, while the mechanical robustness of the PM can be guaranteed comparing with the traditional partial magnet segmentation method.

Wang, Z, Luo, C, Anwand, W, Wagner, A, Butterling, M, Rahman, MA, Phillips, MR, Ton-That, C, Younas, M, Su, S & Ling, FC-C 2019, 'Vacancy cluster in ZnO films grown by pulsed laser deposition', Scientific Reports, vol. 9, no. 1.
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AbstractUndoped and Ga-doped ZnO films were grown on c-sapphire using pulsed laser deposition (PLD) at the substrate temperature of 600 °C. Positron annihilation spectroscopy study (PAS) shows that the dominant VZn-related defect in the as-grown undoped ZnO grown with relative low oxygen pressure P(O2) is a vacancy cluster (most likely a VZn-nVO complex with n = 2, 3) rather than the isolated VZn which has a lower formation energy. Annealing these samples at 900 °C induces out-diffusion of Zn from the ZnO film into the sapphire creating the VZn at the film/sapphire interface, which favors the formation of vacancy cluster containing relatively more VZn. Increasing the P(O2) during growth also lead to the formation of the vacancy cluster with relatively more VZn. For Ga-doped ZnO films, the oxygen pressure during growth has significant influence on the electron concentration and the microstructure of the VZn-related defect. Green luminescence (GL) and yellow luminescence (YL) were identified in the cathodoluminescence study (CL) study, and both emission bands were quenched after hydrogen plasma treatment. The origin of the GL is discussed.

Wei, X, Cheng, M, Luo, R, Xu, L & Zhu, J 2019, 'Model predictive virtual power control of brushless doubly‐fed induction generator for fast and smooth grid synchronisation', IET Renewable Power Generation, vol. 13, no. 16, pp. 3080-3087.
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Wei, X, Cheng, M, Zhu, J, Yang, H & Luo, R 2019, 'Finite-Set Model Predictive Power Control of Brushless Doubly Fed Twin Stator Induction Generator', IEEE Transactions on Power Electronics, vol. 34, no. 3, pp. 2300-2311.
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© 1986-2012 IEEE. This paper presents a finite-set model predictive power control (FS-MPPC) method for the brushless doubly fed twin stator induction generator (BDFTSIG) in variable speed constant frequency generation applications. The FS-MPPC controller is developed in a general reference frame from which all other reference frames can be deduced readily. The invariant feature of the predictive power model in various reference frames contributes to the reference frame-free characteristic of the developed FS-MPPC controller, enabling its application more flexible and universal. Besides, the arduous process of control winding flux estimation is avoided in the FS-MPPC controller by choosing state variables that are easy to be obtained. Moreover, the influence of rotor circuit that has long been neglected in the existing controllers for the brushless doubly fed induction machines is embedded within the predictive power model and inherently considered in the FS-MPPC controller, which contributes to accurate power control of the BDFTSIG. Furthermore, the feasibility and effectiveness of the developed FS-MPPC controller regarding different power levels and grid fault conditions are briefly discussed. Finally, numerical simulations and experimental tests are carried out, which demonstrates the effectiveness of the developed FS-MPPC controller.

Welford, A, Maniam, S, Gann, E, Jiao, X, Thomsen, L, Langford, SJ & McNeill, CR 2019, 'Influence of alkyl side-chain type and length on the thin film microstructure and OFET performance of naphthalene diimide-based organic semiconductors', Organic Electronics, vol. 75, pp. 105378-105378.
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Wu, T, Lu, K, Zhu, J, Lei, G, Guo, Y & Tang, S 2019, 'Calculation of Eddy Current Loss in a Tubular Oscillatory LPMSM Using Computationally Efficient FEA', IEEE Transactions on Industrial Electronics, vol. 66, no. 8, pp. 6200-6209.
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© 2018 IEEE. In some special oscillatory applications, especially those operated at high speeds, the eddy current loss of a linear permanent-magnet (PM) synchronous machine (LPMSM) should be fully considered because the loss might be large and concentrated in PMs during the oscillation period. This paper presents a loss analysis method based on computationally efficient finite-element analysis (CE-FEA) for a 20-Hz oscillatory tubular LPMSM. Since the mover speed varies with time, an equally divided model in 1/4 period is introduced to calculate the average PM eddy current loss. The flux density curves in PMs are calculated at 18 intervals by the CE-FEA, through which the change rate of the magnetic flux density is analyzed, considering both the entering and leaving effects and coil end effects. The calculation results show that the eddy current loss is obviously concentrated in PMs near the two ends of coils. The calculation results at a speed of 3.6 m/s obtained by the CE-FEA and two-dimensional and three-dimensional time-stepping FEAs are compared to validate the accuracy. Finally, the proposed method is validated by the experimental test results on a prototype LPMSM.

Wu, W, Qi, W, Zhao, Y, Tang, X, Qiu, Y, Su, D, Fan, H & Wang, G 2019, 'Hollow CeO2 spheres conformally coated with graphitic carbon for high-performance supercapacitor electrodes', Applied Surface Science, vol. 463, pp. 244-252.
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© 2018 Elsevier B.V. Electrode material is essential for supercapacitors which are an important energy storage device that can deliver high power. Herein, we report the successful synthesis of hollow CeO 2 nanospheres conformally coated with graphitic carbon (H-CeO 2 @GC) via a facile hydrothermal method as a kind of electrode materials of supercapacitors. The as-prepared H-CeO 2 @GC hollow spheres presented a high specific surface area (153 m 2 ∙g −1 ), a well-defined hollow structure (a monodisperse size of ∼260 nm with inner diameter of ∼200 nm and shell thickness of ∼30 nm), and nanocrystals of CeO 2 (∼10 nm) conformally encapsulated in ultra-thin graphitic carbon layers. When applied in supercapacitors, the H-CeO 2 @GC hollow spheres delivered a high specific capacitance of 501 F∙g −1 at a current density of 1 A∙g −1 , a high energy/power density, excellent rate capability and long cycle life owing to its unique architecture. In particular, an energy density of 17.2 Wh∙kg −1 with a power density of 2600 W∙kg −1 was achieved. The supercapacitors retained 85% of the specific capacitance (refer to 1 A∙g −1 ) even at a high current density of 15 A∙g −1 and exhibited excellent cycling stability with 93% of the capacity retention after 5000 cycles at 10 A∙g −1 . This work offers a new approach to developing high-performance supercapacitors using the strategy of combining hollow nanosphere architecture and conductive graphitic carbon nanocoating.

Xiao, J, Zhang, F, Tang, K, Li, X, Wang, D, Wang, Y, Liu, H, Wu, M & Wang, G 2019, 'Rational Design of a P2-Type Spherical Layered Oxide Cathode for High-Performance Sodium-Ion Batteries', ACS Central Science, vol. 5, no. 12, pp. 1937-1945.
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© 2019 American Chemical Society. Sodium-ion batteries (SIBs) have been regarded as the most promising candidates for the next-generation energy storage devices owing to their low price and high abundance. However, the development of SIBs is mainly hindered by the instability of cathode materials. Here, we report a new P2-type manganese-rich cathode material, Na0.66Li0.18Mn0.71Mg0.21Co0.08O2 (P2-NaLiMMCO) with uniform spherical structure prepared via a simple solvothermal method and subsequent solid-state reaction. This P2-NaLiMMCO cathode material with uniform microsize secondary spheres and nanosize primary crystalline particles delivers a high initial discharge capacity of 166 mA h g-1 and superior capacity retention, which are superior to most previously reported results. The improved stability of the cathode material was further investigated by the in situ X-ray diffraction technique, which suggests an enhanced reversibility of the cathode material during the desodiation/sodiation process. With the superior electrochemical performance and stable structures, this new P2-NaLiMMCO can serve as a practical cathode material for SIBs.

Xiao, X, Wang, H, Bao, W, Urbankowski, P, Yang, L, Yang, Y, Maleski, K, Cui, L, Billinge, SJL, Wang, G & Gogotsi, Y 2019, 'Two‐Dimensional Arrays of Transition Metal Nitride Nanocrystals', Advanced Materials, vol. 31, no. 33, pp. 1902393-1902393.
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AbstractThe synthesis of low‐dimensional transition metal nitride (TMN) nanomaterials is developing rapidly, as their fundamental properties, such as high electrical conductivity, lead to many important applications. However, TMN nanostructures synthesized by traditional strategies do not allow for maximum conductivity and accessibility of active sites simultaneously, which is a crucial factor for many applications in plasmonics, energy storage, sensing, and so on. Unique interconnected two‐dimensional (2D) arrays of few‐nanometer TMN nanocrystals not only having electronic conductivity in‐plane, but also allowing transport of ions and electrolyte through the porous nanosheets, which are obtained by topochemical synthesis on the surface of a salt template, are reported. As a demonstration of their application in a lithium–sulfur battery, it is shown that 2D arrays of several nitrides can achieve a high initial capacity of >1000 mAh g−1 at 0.2 C and only about 13% degradation over 1000 cycles at 1 C under a high areal sulfur loading (>5 mg cm−2).

Xiong, P, Zhang, X, Wan, H, Wang, S, Zhao, Y, Zhang, J, Zhou, D, Gao, W, Ma, R, Sasaki, T & Wang, G 2019, 'Interface Modulation of Two-Dimensional Superlattices for Efficient Overall Water Splitting', Nano Letters, vol. 19, no. 7, pp. 4518-4526.
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© 2019 American Chemical Society. Molecular-scale modulation of interfaces between different unilamellar nanosheets in superlattices is promising for efficient catalytic activities. Here, three kinds of superlattices from alternate restacking of any two of the three unilamellar nanosheets of MoS2, NiFe-layered double hydroxide (NiFe-LDH), and graphene are systematically investigated for electrocatalytic water splitting. The MoS2/NiFe-LDH superlattice exhibits a low overpotential of 210 and 110 mV at 10 mA cm-2 for oxygen evolution reaction (OER) and alkaline hydrogen evolution reaction (HER), respectively, superior than MoS2/graphene and NiFe-LDH/graphene superlattices. High activity and stability toward the overall water splitting are also demonstrated on the MoS2/NiFe-LDH superlattice bifunctional electrocatalyst, outperforming the commercial Pt/C-RuO2 couple. This outstanding performance can be attributed to optimal adsorption energies of both HER and OER intermediates on the MoS2/NiFe-LDH superlattice, which originates from a strong electronic coupling effect at the heterointerfaces. These results herald the interface modulation of superlattices providing a promising approach for designing advanced electrocatalysts.

Xu, J, Li, T, Zhang, W, Wu, W, Jin, Y, Zhang, X, Su, D & Wang, G 2019, 'Propelling the polysulfide phase transformation of lithium–sulfur battery by VO2-rGO', Journal of Alloys and Compounds, vol. 804, pp. 549-553.
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© 2019 Elsevier B.V. Rather than preventing the dissolution and diffusion of polysulfides, promoting polysulfide conversion through improved polysulfide redox is another promising strategy to suppress the dissolution of polysulfides and enhance the cycle life of sulfur cathodes. We demonstrated that VO2-rGO not only facilities liquid-involving polysulfide redox (Li2S8→Li2S6→Li2S4), but also promotes the effective decompositions of lithium sulfide (Li2S). As evidenced by the visual experiments and DFT calculation, VO2-rGO has strong affinity for polysulfides species. With sulfur loading of 2.15 mg cm−2 and sulfur content of 76 wt%, the reversible capacity retained at 896 mAh g−1 after 200 cycles.

Xu, W, Dian, R, Liu, Y, Hu, D & Zhu, J 2019, 'Robust Flux Estimation Method for Linear Induction Motors Based on Improved Extended State Observers', IEEE Transactions on Power Electronics, vol. 34, no. 5, pp. 4628-4640.
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IEEE Flux estimation is of great importance for high performance linear induction motor (LIM) drives. However, due to the end effects of LIMs, the mutual inductance and secondary resistance are seriously varied with the operation condition changing, and the flux estimation suffers from these LIM parameter variations. To alleviate the influence of these parameter variations, this paper proposes a new flux estimation algorithm based on two improved extended state observers (ESOs) with expanded bandwidth for observing disturbances. One of them is specially designed to observe the ac disturbance at certain frequency. Taking advantage of the improved ESOs, the robustness of the flux observer to parameter deviations can be significantly strengthened, and the vector control strategy based on this new flux observer can achieve better dynamic performance. Lastly, the effectiveness of the proposed method is validated by both simulation and experimental results on an LIM prototype.

Xu, W, Hu, D, Lei, G & Zhu, J 2019, 'System-level efficiency optimization of a linear induction motor drive system', CES Transactions on Electrical Machines and Systems, vol. 3, no. 3, pp. 285-291.
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Yan, K, Wang, J, Zhao, S, Zhou, D, Sun, B, Cui, Y & Wang, G 2019, 'Temperature‐Dependent Nucleation and Growth of Dendrite‐Free Lithium Metal Anodes', Angewandte Chemie, vol. 131, no. 33, pp. 11486-11490.
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AbstractIt is essential to develop a facile and effective method to enhance the electrochemical performance of lithium metal anodes for building high‐energy‐density Li‐metal based batteries. Herein, we explored the temperature‐dependent Li nucleation and growth behavior and constructed a dendrite‐free Li metal anode by elevating temperature from room temperature (20 °C) to 60 °C. A series of ex situ and in situ microscopy investigations demonstrate that increasing Li deposition temperature results in large nuclei size, low nucleation density, and compact growth of Li metal. We reveal that the enhanced lithiophilicity and the increased Li‐ion diffusion coefficient in aprotic electrolytes at high temperature are essential factors contributing to the dendrite‐free Li growth behavior. As anodes in both half cells and full cells, the compact deposited Li with minimized specific surface area delivered high Coulombic efficiencies and long cycling stability at 60 °C.

Yan, K, Wang, J, Zhao, S, Zhou, D, Sun, B, Cui, Y & Wang, G 2019, 'Temperature‐Dependent Nucleation and Growth of Dendrite‐Free Lithium Metal Anodes', Angewandte Chemie International Edition, vol. 58, no. 33, pp. 11364-11368.
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AbstractIt is essential to develop a facile and effective method to enhance the electrochemical performance of lithium metal anodes for building high‐energy‐density Li‐metal based batteries. Herein, we explored the temperature‐dependent Li nucleation and growth behavior and constructed a dendrite‐free Li metal anode by elevating temperature from room temperature (20 °C) to 60 °C. A series of ex situ and in situ microscopy investigations demonstrate that increasing Li deposition temperature results in large nuclei size, low nucleation density, and compact growth of Li metal. We reveal that the enhanced lithiophilicity and the increased Li‐ion diffusion coefficient in aprotic electrolytes at high temperature are essential factors contributing to the dendrite‐free Li growth behavior. As anodes in both half cells and full cells, the compact deposited Li with minimized specific surface area delivered high Coulombic efficiencies and long cycling stability at 60 °C.

Yang, T, Yang, D, Mao, Q, Liu, Y, Bao, L, Chen, Y, Xiong, Q, Ji, Z, Ling, CD, Liu, H, Wang, G & Zheng, R 2019, 'In-situ synthesis of Ni–Co–S nanoparticles embedded in novel carbon bowknots and flowers with pseudocapacitance-boosted lithium ion storage', Nanotechnology, vol. 30, no. 15, pp. 155701-155701.
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© 2019 IOP Publishing Ltd. We design a facile approach to prepare a bimetallic transition-metal-sulphide-based 3D hierarchically-ordered porous electrode based on bimetallic metal-organic frameworks (Ni-Co-MOFs) by using confinement growth and in-situ sulphurisation techniques. In the novel resulting architectures, Ni-Co-S nanoparticles are confined in bowknot-like and flower-like carbon networks and are mechanically isolated but electronically well-connected, where the carbon networks with a honeycomb-like feature facilitate electron transfer with uninterrupted conductive channels from all sides. Moreover, these hierarchically-ordered porous structures together with internal voids can accommodate the volume expansion of the embedded Ni-Co-S nanoparticles. The pseudocapacitive behaviours displayed in the NCS@CBs and NCS@CFs occupied a significant portion in the redox processes. Because of these merits, both the as-built bowknot and flower networks show excellent electrochemical properties for lithium storage with superior rate capability and robust cycling stability (994 mAh g-1 for NCS@CBs and 888 mAh g-1 for NCS@CFs after 200 cycles). This unique 3D hierarchically-ordered structural design is believed to hold great potential applications in propagable preparation of carbon networks teamed up with sulphide nanocrystals for high energy storage.

Ye, X, Yang, Z, Zhu, J & Guo, Y 2019, 'Modeling and Operation of a Bearingless Fixed-Pole Rotor Induction Motor', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2, pp. 1-4.
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© 2002-2011 IEEE. The rotor currents are induced by both suspension force winding magnetic field and torque winding magnetic field in the traditional bearingless induction motors (BIMs). Due to the currents induced by the suspension force winding, there are errors in the generation of radial suspension forces. To address such problems, a novel BIM with fixed-pole rotor, called bearingless fixed-pole rotor induction (BFPRI) motor is proposed. The structure of BFPRI motor is first analyzed and the mathematical models of radial suspension forces are deduced. Based on the finite element analysis, the induced currents and radial suspension forces are also investigated and compared with the traditional BIM. Finally, the prototype motor is built and experimental research is carried out. In this novel motor, only the torque winding magnetic field induces currents in the rotor, which makes the precision of radial suspension forces higher and thereby reduces the complexity of BIM control system. The effectiveness of the proposed BFPRI motor is validated by both simulation and experiments.

Yu, X, Yu, Z-Y, Zhang, X-L, Zheng, Y-R, Duan, Y, Gao, Q, Wu, R, Sun, B, Gao, M-R, Wang, G & Yu, S-H 2019, '“Superaerophobic” Nickel Phosphide Nanoarray Catalyst for Efficient Hydrogen Evolution at Ultrahigh Current Densities', Journal of the American Chemical Society, vol. 141, no. 18, pp. 7537-7543.
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Copyright © 2019 American Chemical Society. The design of highly efficient non-noble-metal electrocatalysts for large-scale hydrogen production remains an ongoing challenge. We report here a Ni2P nanoarray catalyst grown on a commercial Ni foam substrate, which demonstrates an outstanding electrocatalytic activity and stability in basic electrolyte. The high catalytic activity can be attributed to the favorable electron transfer, superior intrinsic activity, and the intimate connection between the nanoarrays and their substrate. Moreover, the unique 'superaerophobic' surface feature of the Ni2P nanoarrays enables a remarkable capability to withstand internal and external forces and release the in situ generated H2 bubbles in a timely manner at large current densities (such as >1000 mA cm-2) where the hydrogen evolution becomes vigorous. Our results highlight that an aerophobic structure is essential to catalyze gas evolution for large-scale practical applications.

Yuan, Z, Dong, L, Gao, Q, Huang, Z, Wang, L, Wang, G & Yu, X 2019, 'SnSb alloy nanoparticles embedded in N-doped porous carbon nanofibers as a high-capacity anode material for lithium-ion batteries', Journal of Alloys and Compounds, vol. 777, pp. 775-783.
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© 2018 SnSb alloy is a promising anode material for lithium-ion batteries due to its high specific capacity. However, the large volume change in the process of charge/discharge causes significant pulverizing of SnSb alloy particles, which leads to a rapid capacity fading. This paper reports the synthesis of homogenous SnSb nanoparticles that are embedded in N-doped porous carbon nanofibers through electrospinning technique with LiN3 serving as poregen agent. This distinctive structure prevents the direct contact of SnSb nanoparticles with the electrolyte and provides enough space for the volume change of SnSb alloy during the Li+ insertion/extraction process, enabling this material to deliver a high reversible capacity of 892 mA h g−1 after 100th cycle at 100 mA g−1, and a stable capacity of 487 mA h g−1 after 1000 cycles at 2000 mA g−1. These results highlight the importance of the synergistic effect of SnSb alloy nanoparticles and N-doped porous carbon nanofibers for the high performance of lithium-ion batteries.

Zakria, M, Huynh, TT, Ling, FCC, Su, SC, Phillips, MR & Ton-That, C 2019, 'Highly Luminescent MgZnO/ZnO Multiple Quantum Wells for Photonics Devices', ACS Applied Nano Materials, vol. 2, no. 4, pp. 2574-2579.
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Copyright © 2019 American Chemical Society. Multiple quantum wells (MQWs) have enabled a myriad of technological applications; however, their optical emission is currently severely constrained by the presence of undesirable defects, which limit their performance in advanced photonic devices. Here, we present a new route to achieve highly luminescent oxide-based MQWs by rapid remote plasma annealing (RRPA) in hydrogen. We demonstrate that the optical emission from the MgZnO/ZnO MQWs can be enhanced substantially by this plasma method, with its emission intensity increased by more than 10 times after being treated for 40 s. Concurrently, the emissions associated with both basal stacking faults and point defects are completely quenched. Based on temperature- and excitation-density-dependent luminescence results, the enhancement of the MQW emission is attributed to the passivation of competitive recombination channels. Additionally, the exciton-optical phonon coupling strength, deduced from the temperature-dependent MQW spectral line width, shows clear evidence for significantly enhanced phonon coupling as a result of exciton screening effects. This rapid plasma procedure presents a versatile method to enhance the optical quality of oxide-based MQW structures and could open the door to high-efficiency photonic devices. ©

Zhan, Y, Guo, Y, Zhu, J, Liang, B & Yang, B 2019, 'Comprehensive influences measurement and analysis of power converter low frequency current ripple on PEM fuel cell', International Journal of Hydrogen Energy, vol. 44, no. 59, pp. 31352-31359.
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© 2019 Hydrogen Energy Publications LLC To deeply understand the influences of power converter's low frequency current ripple (LFCR) and harmonics on a proton exchange membrane fuel cell (PEMFC) in its power conditioning system (PCS), a comprehensive measurement and analysis of the influences of LFCR and harmonics on PEMFC's performance and durability is investigated in this paper. Based on an equivalent circuit model of PEMFC stack and a mechanism model for evaluating the LFCR effects on the PEMFC, this paper studies primarily and systematically the comprehensive influences of LFCR and harmonics on PEMFC performances and durability, such as (1) degrading the PEMFC performance, (2) shortening the lifetime of PEMFC, (3) reducing the stack output power, (4) lowing its availability efficiency, (5) producing more heat and raising the PEMFC temperature, (6) consuming more fuel, and (7) decreasing the fuel utilization. Finally, a Horizon 300 W PEMFC stack is implemented and tested.

Zhang, G, Xu, B, Chong, H, Wei, W, Wang, C & Wang, G 2019, 'Effect of glyphosate on X-ray diffraction of copper films prepared by electrochemical deposition', RSC Advances, vol. 9, no. 25, pp. 14016-14023.
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Quantitative probing of glyphosate by combining electrochemical deposition and X-ray diffraction methods.

Zhang, J, Sun, B, Zhao, Y, Tkacheva, A, Liu, Z, Yan, K, Guo, X, McDonagh, AM, Shanmukaraj, D, Wang, C, Rojo, T, Armand, M, Peng, Z & Wang, G 2019, 'A versatile functionalized ionic liquid to boost the solution-mediated performances of lithium-oxygen batteries', Nature Communications, vol. 10, no. 1.
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AbstractDue to the high theoretical specific energy, the lithium–oxygen battery has been heralded as a promising energy storage system for applications such as electric vehicles. However, its large over-potentials during discharge–charge cycling lead to the formation of side-products, and short cycle life. Herein, we report an ionic liquid bearing the redox active 2,2,6,6-tetramethyl-1-piperidinyloxy moiety, which serves multiple functions as redox mediator, oxygen shuttle, lithium anode protector, as well as electrolyte solvent. The additive contributes a 33-fold increase of the discharge capacity in comparison to a pure ether-based electrolyte and lowers the over-potential to an exceptionally low value of 0.9 V. Meanwhile, its molecule facilitates smooth lithium plating/stripping, and promotes the formation of a stable solid electrolyte interface to suppress side-reactions. Moreover, the proportion of ionic liquid in the electrolyte influences the reaction mechanism, and a high proportion leads to the formation of amorphous lithium peroxide and a long cycling life (> 200 cycles). In particular, it enables an outstanding electrochemical performance when operated in air.

Zhang, S, Li, X-Y, Yang, W, Tian, H, Han, Z, Ying, H, Wang, G & Han, W-Q 2019, 'Novel Synthesis of Red Phosphorus Nanodot/Ti₃C₂T_x MXenes from Low-Cost Ti₃SiC₂ MAX Phases for Superior Lithium- and Sodium-Ion Batteries', ACS Applied Materials & Interfaces, vol. 11, no. 45, pp. 42086-42093.
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© 2019 American Chemical Society. MXenes, synthesized from MAX, have emerged as new energy-storage materials for a good combination of metallic conductivity and rich surface chemistry. The reported MXenes are synthesized mostly from Al-based MAX. It is still a big challenge to synthesize MXenes from abundant Si-based MAX because of its strong Ti-Si bonds. Here, we report for the first time a high-energy ultrasonic cell-crushing extraction method to successfully prepare Ti3C2Tx MXenes from Si-based MAX using a single low-concentration etchant. This novel strategy for preparing MXenes has a high extraction efficiency and is a fast preparation process of less than 2 h for selective etching of Si. Furthermore, through the high-energy ball-milling technology, unique P-O-Ti bonded red phosphorus nanodot/Ti3C2Tx (PTCT) composites were successfully prepared, which enable superior electrochemical performance in lithium- and sodium-ion batteries because of the double-morphology structure, where the amorphous nano red phosphorus particles were strongly absorbed to Ti3C2Tx MXene sheets, facilitating the transport of alkali ions during cycling processes. This novel synthesis method of Ti3C2Tx MXenes from Si-based MAX and unique P-O-Ti bonded PTCT composites opens a new door for preparing high-performance MXene-based materials and facilitating the development of low-cost MXenes and other two-dimensional materials for next-generation energy storage.

Zhang, X, Pei, Z, Wang, C, Yuan, Z, Wei, L, Pan, Y, Mahmood, A, Shao, Q & Chen, Y 2019, 'Flexible Zinc‐Ion Hybrid Fiber Capacitors with Ultrahigh Energy Density and Long Cycling Life for Wearable Electronics', Small, vol. 15, no. 47, pp. 1903817-1903817.
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AbstractEmerging wearable electronics require flexible energy storage devices with high volumetric energy and power densities. Fiber‐shaped capacitors (FCs) offer high power densities and excellent flexibility but low energy densities. Zn‐ion capacitors have high energy density and other advantages, such as low cost, nontoxicity, reversible Faradaic reaction, and broad operating voltage windows. However, Zn‐ion capacitors have not been applied in wearable electronics due to the use of liquid electrolytes. Here, the first quasisolid‐state Zn‐ion hybrid FC (ZnFC) based on three rationally designed components is demonstrated. First, hydrothermally assembled high surface area and conductive reduced graphene oxide/carbon nanotube composite fibers serve as capacitor‐type positive electrodes. Second, graphite fibers coated with a uniform Zn layer work as battery‐type negative electrodes. Third, a new neutral ZnSO4‐filled polyacrylic acid hydrogel act as the quasisolid‐state electrolyte, which offers high ionic conductivity and excellent stretchability. The assembled ZnFC delivers a high energy density of 48.5 mWh cm−3 at a power density of 179.9 mW cm−3. Further, Zn dendrite formation that commonly happens under high current density is efficiently suppressed on the fiber electrode, leading to superior cycling stability. Multiple ZnFCs are integrated as flexible energy storage units to power wearable devices under different deformation conditions.

Zhao, S, Yan, K, Munroe, P, Sun, B & Wang, G 2019, 'Construction of Hierarchical K_1.39Mn₃O₆ Spheres via AlF₃ Coating for High‐Performance Potassium‐Ion Batteries', Advanced Energy Materials, vol. 9, no. 10, pp. 1803757-1803757.
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AbstractPotassium‐ion batteries are attracting great interest for emerging large‐scale energy storage owing to their advantages such as low cost and high operational voltage. However, they are still suffering from poor cycling stability and sluggish thermodynamic kinetics, which inhibits their practical applications. Herein, the synthesis of hierarchical K1.39Mn3O6 microspheres as cathode materials for potassium‐ion batteries is reported. Additionally, an effective AlF3 surface coating strategy is applied to further improve the electrochemical performance of K1.39Mn3O6 microspheres. The as‐synthesized AlF3 coated K1.39Mn3O6 microspheres show a high reversible capacity (about 110 mA h g−1 at 10 mA g−1), excellent rate capability, and cycling stability. Galvanostatic intermittent titration technique results demonstrate that the increased diffusion kinetics of potassium‐ion insertion and extraction during discharge and charge processes benefit from both the hierarchical sphere structure and surface modification. Furthermore, ex situ X‐ray diffraction measurements reveal that the irreversible structure evolution can be significantly mitigated via surface modification. This work sheds light on rational design of high‐performance cathode materials for potassium‐ion batteries.

Zhao, Y, Wang, S, Liu, H, Guo, X, Zeng, X, Wu, W, Zhang, J & Wang, G 2019, 'Porous Mo2C nanorods as an efficient catalyst for the hydrogen evolution reaction', Journal of Physics and Chemistry of Solids, vol. 132, pp. 230-235.
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© 2019 Elsevier Ltd Generate hydrogen fuel from electrochemical water splitting has been considered as a promising approach. However, to obtain the low-cost and high performance catalysts towards hydrogen evolution reaction (HER)which can be applied in both alkaline and acid solution remains a challenge. Herein, we synthesized an active and stable HER catalyst composed of Mo2C nanocrystals embedded in the nanocarbon layers (Mo2C@C)by using MoO3 nanorods as precursor. Benefiting from the porous one dimensional structure and ultrafine Mo2C nanocrystals, Mo2C@C exhibits high HER catalytic activity for 10 mA cm−2 with the overpotential of 119 mV in 1 M KOH solution and 170 mV in 0.5 M H2SO4 solution, respectively. Moreover, Mo2C@C displays long durability during the HER process with almost no decay and maintains the porous one dimensional architecture after the HER stability test. This study offers the guideline for the further design and fabrication of the nanostructured HER electrocatalysts in wide pH range.

Zhou, D, Tkacheva, A, Tang, X, Sun, B, Shanmukaraj, D, Li, P, Zhang, F, Armand, M & Wang, G 2019, 'Stable Conversion Chemistry‐Based Lithium Metal Batteries Enabled by Hierarchical Multifunctional Polymer Electrolytes with Near‐Single Ion Conduction', Angewandte Chemie International Edition, vol. 58, no. 18, pp. 6001-6006.
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AbstractThe low Coulombic efficiency and serious safety issues resulting from uncontrollable dendrite growth have severely impeded the practical applications of lithium (Li) metal anodes. Herein we report a stable quasi‐solid‐state Li metal battery by employing a hierarchical multifunctional polymer electrolyte (HMPE). This hybrid electrolyte was fabricated via in situ copolymerizing lithium 1‐[3‐(methacryloyloxy)propylsulfonyl]‐1‐(trifluoromethanesulfonyl)imide (LiMTFSI) and pentaerythritol tetraacrylate (PETEA) monomers in traditional liquid electrolyte, which is absorbed in a poly(3,3‐dimethylacrylic acid lithium) (PDAALi)‐coated glass fiber membrane. The well‐designed HMPE simultaneously exhibits high ionic conductivity (2.24×10−3 S cm−1 at 25 °C), near‐single ion conducting behavior (Li ion transference number of 0.75), good mechanical strength and remarkable suppression for Li dendrite growth. More intriguingly, the cation permselective HMPE efficiently prevents the migration of negatively charged iodine (I) species, which provides the as‐developed Li‐I batteries with high capacity and long cycling stability.

Zhou, D, Tkacheva, A, Tang, X, Sun, B, Shanmukaraj, D, Li, P, Zhang, F, Armand, M & Wang, G 2019, 'Stable Conversion Chemistry‐Based Lithium Metal Batteries Enabled by Hierarchical Multifunctional Polymer Electrolytes with Near‐Single Ion Conduction', Angewandte Chemie, vol. 131, no. 18, pp. 6062-6067.
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AbstractThe low Coulombic efficiency and serious safety issues resulting from uncontrollable dendrite growth have severely impeded the practical applications of lithium (Li) metal anodes. Herein we report a stable quasi‐solid‐state Li metal battery by employing a hierarchical multifunctional polymer electrolyte (HMPE). This hybrid electrolyte was fabricated via in situ copolymerizing lithium 1‐[3‐(methacryloyloxy)propylsulfonyl]‐1‐(trifluoromethanesulfonyl)imide (LiMTFSI) and pentaerythritol tetraacrylate (PETEA) monomers in traditional liquid electrolyte, which is absorbed in a poly(3,3‐dimethylacrylic acid lithium) (PDAALi)‐coated glass fiber membrane. The well‐designed HMPE simultaneously exhibits high ionic conductivity (2.24×10−3 S cm−1 at 25 °C), near‐single ion conducting behavior (Li ion transference number of 0.75), good mechanical strength and remarkable suppression for Li dendrite growth. More intriguingly, the cation permselective HMPE efficiently prevents the migration of negatively charged iodine (I) species, which provides the as‐developed Li‐I batteries with high capacity and long cycling stability.

Zhu, G, Liu, X, Li, L, Chen, H, Tong, W & Zhu, J 2019, 'Cooling System Design of a High-Speed PMSM Based on a Coupled Fluidic–Thermal Model', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2, pp. 1-5.
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© 2002-2011 IEEE. To avoid overheating of a totally enclosed high-speed permanent magnet synchronous machine (PMSM) with an amorphous alloy core, this paper proposes a hybrid cooling system with both radial and axial vents to maintain the temperature rise below the rated value. The analytical models of cooling ability and frictional loss generated in the rotor ducts are derived in relation to the cooling structure parameters. The sensitivity of each parameter to the cooling effect is researched, and the parameter scopes are then determined. A coupled fluidic-thermal model based on the cell method is developed to predict numerically the temperature distribution to check the effectiveness of the cooling system. By analyzing the influences of the numbers and sizes of the cooling ducts on the efficient cooling air quantity and temperature, the feasible parameters that yield reasonable temperature distribution can be determined. The theoretical results are confirmed by experimental test results on a 15-kW 30 000-r/min PMSM prototype.

Abuhilaleh, M, Li, L, Zhu, J & Hossain, MJ 1970, 'Distributed Control and Power Management Strategy for Parallel Bidirectional Power Converters in Hybrid Microgrids', IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society, IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society, IEEE, Lisbon, Portugal.
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This paper presents a new approach of distributed coordinated control for multiple interlinking converters (ILCs) to regulate the power flow across the hybrid AC/DC microgrid composed of AC and DC sub-microgrids (SMGs). These SMGs are linked together by multiple parallel ILCs that are operated as bidirectional power converters. The proposed control system not only allows reliable management and control of the power flow between SMGs but also regulates the DC voltage for the DC SMGs as part of the process. One of the key gains of this structure is the mitigation of the circulating current that results from the parallel operation of the converters. Although the circulating current is more present at the AC side, it can also exist on the DC side. At the AC side, this is achieved through the implementation of the d-q-0 axis control strategy. The presented outer control loop is a modified arrangement that could not only ensure accurate power sharing but also suppress the circulating current at the DC side.

Asari, AR, Guo, Y & Zhu, J 1970, 'Performances of SOMALOY 700 (5P) and SOMALOY 500 Materials under 1-D Alternating Magnetic Flux Density', 2019 International UNIMAS STEM 12th Engineering Conference (EnCon), 2019 International UNIMAS STEM 12th Engineering Conference (EnCon), IEEE, Kuching, Malaysia, pp. 52-58.
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© 2019 IEEE. In high magnetization frequency of the high speed electrical machine, core loss dissipation is a main contributor of the power loss that gives high percentage of loss compared to the other losses. Previously, the engineers has considered SOMALOY 500 as a core of electrical machine but they still aim for the lower loss magnetic material that can offer higher efficiency during the operation of the electrical machines.. There is no standardization for rotational core loss of magnetic material that needs more effort in order to predict the core loss accurately. In this paper, core loss of SOMALOY 700 (5P) is calculated and analyzed to identify the magnetic properties of that material. The magnetic properties of SOMALOY 700 (5P) material are properly measured under alternating magnetic fluxes at 50 Hz, 100 Hz, 500 Hz and 1000 Hz by using 3-D tester. The material characteristics under alternating fluxes are important to estimate the total rotational core loss in the future. LabVIEW and Mathcad software are used for the data acquisition and analysis, respectively. The performances of SOMALOY 700 (5P) are compared to SOMALOY 500 by plotting the core loss curves and hysteresis loops. The finding shows the core loss of both samples is proportional to the squared of magnetic flux density. This study also revealed that the core loss of SOMALOY 700 (5P) and SOMALOY 500 are 6 kg/Watt and 12 kg/Watt when the magnetic field is at 1.5 T. It concludes that the SOMALOY 700 (5P) offers lower core loss compared to the SOMALOY 500 and more suitable to be used in producing high performance of electrical machines. The details of core losses for both SOMALOY materials are important in order to provide the significance information to the real engineers in designing the electrical or electromagnetic machines in the future.

Hu, C, Sun, X, Yang, Z, Lei, G, Guo, Y & Zhu, J 1970, 'A State Feedback Controller for PMSMs Based on Penalty Term Augmented Seeker Optimization Algorithm', 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), IEEE.
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© 2019 IEEE. This paper presents the design of a state feedback controller (SFC) for permanent-magnet synchronous motor (PMSM) drive. First, two integrals, the integral of rotor speed error and d-axis current error are added into the discretized state space model of PMSM to eliminate steady-state error in speed and id. Then, the seeker optimization algorithm (SOA) is employed to get the parameters of the proposed SFC. Also, in order to avoid overshoots in speed tracking, a penalty term is added to the fitness function. Finally, the SOA based SFC with and without the penalty term are compared in experiments.

Khan, SA, Guo, Y, Habib Khan, MN, Siwakoti, Y & Zhu, J 1970, 'Model Predictive Control without Weighting Factors for T-type Multilevel Inverters with Magnetic-Link and Series Stacked AC-DC Modules', 2019 IEEE Energy Conversion Congress and Exposition (ECCE), 2019 IEEE Energy Conversion Congress and Exposition (ECCE), IEEE, Baltimore, MD, USA, pp. 5603-5609.
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© 2019 IEEE. This paper presents a multiport magnetic-link based T-type multilevel inverter topology and associated control scheme. The proposed structure comprises of series stacked AC-DC modules connected to a high-frequency magnetic-link, which boost the input DC-link voltage level significantly, and generates the required dc-link voltages for the multilevel inverter stage. The desired number of the output voltage level can be realized by cascading series stacked AC-DC modules and bidirectional switches. Due to inherent voltage balancing capability of the magnetic-link based structure, this topology does not require any control scheme to balance the series connected capacitors in the DC-bus. Thus, it reduces the control complexity. Moreover, the magnetically isolated structure eliminates the leakage and DC current injection into the grid from DC sources, like photovoltaic (PV) module. The proposed structure has the capability to integrate multiple sources operating with different voltage levels, and consequently, reduces the number of components and control complexity. In this work, multilevel voltage synthesizing, active and reactive power control capability are realized by using the finite control set model predictive control (FCS-MPC) algorithm. A prototype multilevel inverter incorporating three stacked AC-DC modules, designed for seven levels operation has been built and tested to verify the circuit performance and associated control scheme.

Kiran, MR, Farrok, O, Islam, MR & Zhu, J 1970, 'Characterization of the Optimized High Frequency Transformer Using Nanocrystalline and Amorphous Magnetic Materials', 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), IEEE.
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High frequency transformers (HFTs) suffer from high core loss because of high operating frequencies and low magnetic flux saturation of core materials. Latest soft-magnetic materials having the properties of higher flux density, low core loss at medium or high frequencies and high electrical resistivity greatly contribute to the solution of high core losses of HFTs. In this paper, a toroidal core HFT is optimized using human intervened genetic algorithm, mathematically modeled, and characterized in terms of low core loss, better load-power characteristics, and higher efficiency as well as amorphous and nanocrystalline magnetic materials are compared based on their electromagnetic properties. It is nominated that the characterization will lead significant role in the development of next generation HFTs.

Liu, C, Wang, Y, Lei, G, Guo, Y & Zhu, J 1970, 'Comparative Study of Axial Flux Vernier Machine with SMC Cores for Electric Vehicle Application', 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), IEEE, Harbin, China.
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© 2019 IEEE. Two high performance axial flux Vernier machines (AFVM) with soft magnetic composite (SMC) cores and one of that with silicon steel cores were proposed for electric vehicle application and quantitatively studied in this paper. By using 3D finite element method (FEM), the torque ability and power factor of above three machines have been optimized, and then the main performance are compared. With the combination of spoke magnet rotor structure and 3-D stator structure, the proposed AFVM1 can own the benefit of highest power factor when compared with other machines, and AFVM2 with double rotor configuration and 3D stator structure can have much higher torque ability comparing with the AFVM with silicon steel cores. It can be seen that with the adoption of SMC material the performance of traditional AFVM has been improved greatly.

Ma, B, Zheng, J, Lei, G & Zhu, J 1970, 'A Robust Design Optimization Approach for Electromagnetic DevicesConsidering Probability Uncertainties', the 22nd International Conference on the Computation of Electromagnetic Fields, Paris.

Nguyen, D-A, Bui, D-H, Iacopi, F & Tran, X-T 1970, 'An Efficient Event-driven Neuromorphic Architecture for Deep Spiking Neural Networks', 2019 32nd IEEE International System-on-Chip Conference (SOCC), 2019 32nd IEEE International System-on-Chip Conference (SOCC), IEEE, Singapore, Singapore, pp. 144-149.
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© 2019 IEEE. Deep Neural Networks (DNNs) have been successfully applied to various real-world machine learning applications. However, performing large DNN inference tasks in real-time remains a challenge due to its substantial computational costs. Recently, Spiking Neural Networks (SNNs) have emerged as an alternative way of processing DNN'fs task. Due to its eventbased, data-driven computation, SNN reduces both inference latency and complexity. With efficient conversion methods from traditional DNN, SNN exhibits similar accuracy, while leveraging many state-of-the-art network models and training methods. In this work, an efficient neuromorphic hardware architecture for image recognition task is presented. To preserve accuracy, the analog-to-spiking conversion algorithm is adopted. The system aims to minimize hardware area cost and power consumption, enabling neuromorphic hardware processing in edge devices. Simulation results have shown that, with the MNIST digit recognition task, the system has achieved × 20 reduction in terms of core area cost compared to the state-of-the-art works, with an accuracy of 94.4%, core area of 15 μ m2 at a maximum frequency of 250 MHz.

Paul, AK, Zahid Hassan, M, Islam, MR & Zhu, JG 1970, 'Graphene/Gold Based Photonic Crystal Fiber Plasmonic Temperature Sensor for Electric Vehicle Applications', 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), IEEE.
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An octagonal photonic crystal fiber (PCF) based surface plasmon resonance (SPR) temperature sensor is proposed where graphene/gold and ethanol are used as a plasmonic material and sensing medium, respectively. The proposed PCF based SPR temperature sensor is numerically simulated by finite element method (FEM) based simulation tool and result is processed by using MATLAB environment. Numerical results indicate that the proposed temperature sensor shows the possible maximum wavelength/temperature sensitivity of 1450 pm/°C for graphene plasmonic and 2500 pm/°C for gold plasmonic, calculated using wavelength interrogation method. It is anticipated that the proposed SPR temperature sensor can be reliably applied to monitor the temperature of battery used for electric vehicles (EVs), transformer oil etc.

Ton-That, C, Huynh, T, Lee Cheong Lem, L, Kuramata, A & Phillips, M 1970, 'Kinetics of charge carrier recombination in beta-Ga2O3 single crystals (Conference Presentation)', Oxide-based Materials and Devices X, Oxide-based Materials and Devices X, SPIE, p. 28.
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Xiong, H, Fu, H, Zhu, J, Liu, J, Luo, X & Qiu, B 1970, 'Design of 3-D Magnetic Field Sensor and Calibration Platform for TMS', 2019 IEEE International Conference on Mechatronics and Automation (ICMA), 2019 IEEE International Conference on Mechatronics and Automation (ICMA), IEEE, Tianjin, China, pp. 1823-1829.
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© 2019 IEEE. In order to build an accurate measurement structure for transcranial magnetic stimulation (TMS) pre-testing, a kind of three - dimensional (3-D) magnetic field sensor and calibration platform are designed in this paper. This measurement structure is made up of 883-D magnetic field sensors. The 3-D magnetic field sensors based on Faraday law of electromagnetic induction are used to accurately measure pulsed magnetic fields generated by the stimulating coil. The coefficients of the sensors are calibrated in a designed 3-D calibration platform. And a series of experiments are carried out to verify the accuracy and stability of the sensors. The results from experiments indicate that the average measurement accuracy of 88 sensors is 1% and sensor performance is stable. In conclusion, this work provides a promising way to avoid direct human experiments and improve the security of TMS.

Zhu, L, Han, X, Tang, R & Zhu, J 1970, 'Loss Analysis of the Permanent Magnet Motor with an Amorphous Stator Core by Considering the Influences of Manufacturing Processes', 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), 2019 22nd International Conference on Electrical Machines and Systems (ICEMS), IEEE.
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© 2019 IEEE. This paper presents the results of experimental trials carried out on a permanent magnet motor with an amorphous stator core. The magnetization performances and iron loss characteristics of the manufactured amorphous core were measured. Losses of two permanent magnet motors with amorphous core and silicon steel core were calculated and compared by considering the influences of mechanic stresses induced in the amorphous core manufacturing processes. Total losses and efficiencies of the permanent magnet motors were tested and compared. It is demonstrated that the efficiency superiority of the permanent magnet motor with an amorphous core gets weaken as the load ratio increases.

Fiedler, S, Lee, LO, Lem, C, Schleuning, M, Hoffmann, A, Ton-That, C & Phillips, MR 2019, 'Correlative Study of Enhanced Excitonic Emission in ZnO Coated with Al Nanoparticles using Electron and Laser Excitation'.

Fiedler, S, Lem, LOLC, Ton-That, C & Phillips, MR 2019, 'The role of surface depletion layer effects on the enhancement of the UV emission in ZnO induced by a nanostructured Al surface coating'.

Fiedler, S, Lem, LOLC, Ton-That, C, Hoffmann, A & Phillips, MR 2019, 'Enhancement of the UV emission from gold/ZnO nanorods exhibiting no green luminescence'.