Wang, Y, Kretschmer, K, Zhang, J, Mondal, AK, Guo, X & Wang, G 2016, 'Organic sodium terephthalate@graphene hybrid anode materials for sodium-ion batteries', RSC ADVANCES, vol. 6, no. 62, pp. S7098-S7102.View/Download from: UTS OPUS or Publisher's site
Mondal, AK, Wang, B, Su, D, Wang, Y, Chen, S, Zhang, X & Wang, G 2014, 'Graphene/MnO2 hybrid nanosheets as high performance electrode materials for supercapacitors', Materials Chemistry And Physics, vol. 143, no. 2, pp. 740-746.View/Download from: UTS OPUS or Publisher's site
Graphene/MnO2 hybrid nanosheets were prepared by incorporating graphene and MnO2 nanosheets in ethylene glycol. Scanning electron microscopy and transmission electron microscopy analyses confirmed nanosheet morphology of the hybrid materials. Graphene/MnO2 hybrid nanosheets with different ratios were investigated as electrode materials for supercapacitors by cyclic voltammetry (CV) and galvanostatic chargedischarge in 1 M Na2SO4 electrolyte. We found that the graphene/MnO2 hybrid nanosheets with a weight ratio of 1:4 (graphene:MnO2) delivered the highest specific capacitance of 320 F g-1. Graphene/MnO2 hybrid nanosheets also exhibited good capacitance retention on 2000 cycles.
Mondal, AK, Su, D, Wang, Y, Chen, S, Liu, Q & Wang, G 2014, 'Microwave hydrothermal synthesis of urchin-like NiO nanospheres as electrode materials for lithium-ion batteries and supercapacitors with enhanced electrochemical performances', Journal Of Alloys And Compounds, vol. 582, no. 1, pp. 522-527.View/Download from: UTS OPUS or Publisher's site
Urchin-like NiO nanospheres were synthesised by a microwave hydrothermal method. The as-synthesised NiO nanospheres were characterised by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. It was found that NiO nanosphere consists of a nanoporous structure and nanosize crystals. When applied as anode materials in lithium-ion batteries, NiO nanospheres exhibited a high reversible specific capacity of 1027 mA h g-1, an excellent cycling performance and a good high rate capability. NiO nanospheres also showed a high specific capacitance as electrode materials for supercapacitors.
Wang, Y, Sharma, N, Su, D, Bishop, DP, Ahn, H & Wang, G 2013, 'High capacity spherical Li[Li0.24Mn0.55Co0.14Ni0.07]O2 cathode material for lithium ion batteries', Solid State Ionics, vol. 233, pp. 12-19.View/Download from: UTS OPUS or Publisher's site
Li[Li0.24Mn0.55Co0.14Ni0.07]O2 cathode materials with controlled spherical morphology and particle size in the range of 5â10 Î¼m were synthesized by a modified co-precipitation method. The crystal structure of Li[Li0.24Mn0.55Co0.14Ni0.07]O2 was investigated by Rietveld analysis of structural models using X-ray and neutron powder diffraction data, indicating the presence of Li2MnO3 in the final product. Li[Li0.24Mn0.55Co0.14Ni0.07]O2 shows low initial irreversible capacity loss (47.2 mAh/g), high reversible capacity (264.6 mAh/g), good capacity retention (90.4% over 50 cycles) and satisfactory rate capability when used as the cathode material in lithium ion batteries. X-ray photoelectron spectroscopy analysis of the pristine, charged and discharged electrodes of Li[Li0.24Mn0.55Co0.14Ni0.07]O2 reveals that the Mn4 +/Mn3 + redox couple participates in the delithiation/lithiation process. Overall, the improved electrochemical performance of the Li[Li0.24Mn0.55Co0.14Ni0.07]O2 electrode can be ascribed to the controlled and specially designed morphology and the composition of the sample that is produced by the co-precipitation method.
Wang, Y, Su, D, Wang, C & Wang, G 2013, 'SnO2@MWCNT nanocomposite as a high capacity anode material for sodium-ion batteries', Electrochemistry Communications, vol. 29, pp. 8-11.View/Download from: UTS OPUS or Publisher's site
We report the synthesis and characterization of SnO2@multiwalled carbon nanotubes (MWCNTs) nanocomposite as a high capacity anode material for sodium-ion battery. SnO2@MWCNT nanocomposite was synthesized by a solvothermal method. SEM and TEM analyses show the uniform distribution of SnO2 nanoparticles on carbon nanotubes. When applied as anode materials in Na-ion batteries, SnO2@MWCNT nanocomposite exhibited a high sodium storage capacity of 839 mAh gâ 1 in the first cycle. SnO2@MWCNT nanocomposite also demonstrated much better cycling performance than that of bare SnO2 nanoparticles and bare MWCNTs. Furthermore, the nanocomposite electrode also showed a good cyclability and an enhanced Coulombic efficiency on cycling.
Wang, B, Wang, Y, Sun, B, Munroe, P & Wang, G 2013, 'Coral-like V2O5 nanowhiskers as high-capacity cathode materials for lithium-ion batteries', RSC Advances, vol. 3, pp. 5069-5075.View/Download from: UTS OPUS or Publisher's site
Coral-like V2O5 nanowhiskers were prepared by a direct electrolytic synthesis method. The as-prepared V2O5 nanowhiskers are approximately 1 Î¼m in length and 50â60 nm in width, which was confirmed by scanning electron microscopy and transmission electron microscopy analysis. When applied as cathode materials in lithium-ion batteries and combined with an ionic liquid electrolyte, the V2O5 nanowhiskers exhibited an initial capacity of 461 mAh gâ1, which is a significant enhancement compared to commercial V2O5 powders. The high rate performance of the V2O5 nanowhiskers was further improved at an elevated working temperature of 50 Â°C. The V2O5 nanowhiskers demonstrated a high specific capacity and an excellent high-rate performance at elevated temperatures.
Sun, B, Wang, Y, Wang, B, Kim, H, Kim, W & Wang, G 2013, 'Porous LiFePO4/C microspheres as high-power cathode materials for lithium ion batteries', Journal of Nanoscience and Nanotechnology, vol. 13, no. 5, pp. 3655-3659.View/Download from: UTS OPUS or Publisher's site
Porous LiFePO4/C microspheres were synthesized by a novel hydrothermal reaction combined with high-temperature calcinations. The morphology of the prepared material was investigated by fieldemission scanning electron microscopy. Porous microspheres with diameters around 1â3m were obtained, which consisting of primary LiFePO4 nanoparticles. The electrochemical performances of the as-prepared LiFePO4 microspheres were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic chargeâdischarge cycling. The carbon coated LiFePO4 microspheres showed lower polarization, higher rate capability, and better cycling stability than that of pristine LiFePO4 microspheres, indicating the potential application as the cathode material for high-power lithium ion batteries.
Liu, Q, Yu, L, Wang, Y, Ji, Y, Horvat, J, Cheng, M, Jia, X & Wang, G 2013, 'Manganese-based layered coordination polymer: Synthesis, structural characterization, magnetic property, and electrochemical performance in lithium-ion batteries', Inorganic Chemistry, vol. 52, pp. 2817-2882.View/Download from: UTS OPUS or Publisher's site
Manganese-based layered coordination polymer ([Mn- (tfbdc)(4,4!-bpy)(H2O)2], Mn-LCP) with microporous structure was synthesized by reaction of 2,3,5,6-tetrafluoroterephthalatic acid(H2tfbdc) and 4,4!-bipyridine(4,4!-bpy) with manganese(II) acetate tetrahydrate in water solution. Mn-LCP was characterized by elemental analysis, IR spectra, thermogravimetric analysis, X-ray single-crystal structure analysis, and powder X-ray diffraction. Magnetic susceptibility data from 300 to 1.8K show that there is a weak antiferromagnetic exchange between Mn(II) ions in Mn-LCP. As anode material, the Mn-LCP electrode exhibits an irreversible high capacity in the first discharge process and a reversible lithium storage capacity of up to about 390 mA h/g from the fourth cycle. It might provide a new method for finding new electrode materials in lithium-ion batteries
Wang, Y, Su, D & Wang, G 2013, 'The Effect Of Carbon Coating On The Electrochemical Performance Of Nanosized Li2FeSiO4 Cathode Materials', Acta Physica Polonica A, vol. 123, no. 2, pp. 279-282.View/Download from: UTS OPUS or Publisher's site
Carbon-coated Li2FeSiO4/C cathode materials have been synthesized through a modified ball-milling process. The physical characterizations of Li2FeSiO4 were conducted by using X-ray powder diffraction, field-emission scanning electron microscopy and transmission electron microscopy techniques. Field-emission scanning electron microscopy and transmission electron microscopy images revealed that Li2FeSiO4/C consists of nanosized particles coated with an amorphous carbon layer. The electrochemical performances of Li2FeSiO4/C cathode materials were evaluated through fully assembled lithium batteries via cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy. The Li2FeSiO4/C cathode materials showed a much improved electrochemical performance in terms of higher specific capacity, better cycling performance and less charge transfer resistance than that of the pristine Li2FeSiO4.
Wang, Y & Wang, G 2013, 'Facile Synthesis of Ge@C Core-Shell Nanocomposites for High-Performance', Chemistry An Asian Journal, vol. 8, no. 12, pp. 3142-3146.View/Download from: UTS OPUS or Publisher's site
Herein, we report a facile and 'green' synthetic route for the preparation of Ge@C core-shell nanocomposites by using a low-cost Ge precursor. Field-emission scanning electron microscopy and transmission electron microscopy analyses confirmed the coreshell nanoarchitecture of the Ge@C nanocomposites, with particle sizes ranging from 60 to 100 nm. Individual Ge nanocrystals were coated by a continuous carbon layer, which had an average thickness of 2 nm. When applied as an anode materials for lithium-ion batteries, the Ge@C nanocomposites exhibited a high initial discharge capacity of 1670 mAhg-1 and superior rate capability. In particular, Ge@C nanocomposite electrodes maintained a reversible capacity of 734 mAhg-1 after repeated cycling at a current density of 800 mAg-1 over 100 cycles.
Mondal, AK, Su, D, Wang, Y, Chen, S & Wang, G 2013, 'Hydrothermal Synthesis of Nickel Oxide Nanosheets for Lithium-Ion Batteries and Supercapacitors with Excellent Performance', Chemistry An Asian Journal, vol. 8, no. 11, pp. 2828-2831.View/Download from: UTS OPUS or Publisher's site
Nickel oxide nanosheets have been successfully synthesized by a facile ethylene glycol mediated hydrothermal method. The morphology and crystal structure of the nickel oxide nanosheets were characterized by X-ray diffraction, field-emission SEM, and TEM. When applied as electrode materials for lithium-ion batteries and supercapacitors, nickel oxide nanosheets exhibited a high, reversible lithium storage capacity of 1193 mAhg-1 at a current density of 500 mAg-1, an enhanced rate capability, and good cycling stability. Nickel oxide nanosheets also demonstrated a superior specific capacitance of 999 Fg-1 at a current density of 20 Ag-1 in supercapacitors.
Wang, Y, Su, D, Ung, AT, Ahn, J & Wang, G 2012, 'Hollow CoFe(2)O(4) nanospheres as a high capacity anode material for lithium ion batteries', Nanotechnology, vol. 23, no. 5, pp. 1-6.View/Download from: UTS OPUS or Publisher's site
Hollow structured CoFe(2)O(4) nanospheres were synthesized by a hydrothermal method. The uniform hollow nanosphere architecture of the as-prepared CoFe(2)O(4) has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis, which give an outer diameter of 200-300 nm and a wall thickness of about 100 nm. CoFe(2)O(4) nanospheres exhibited a high reversible capacity of 1266 mA h g(-1) with an excellent capacity retention of 93.6% over 50 cycles and an improved rate capability. CoFe(2)O(4) could be a promising high capacity anode material for lithium ion batteries.
Wang, Y, Park, J, Sun, B, Ahn, H & Wang, G 2012, 'Wintersweet-flower-like CoFe2O4/MWCNTs hybrid material for high-capacity reversible lithium storage', Chemistry - An Asian Journal, vol. 7, no. 8, pp. 1940-1946.View/Download from: UTS OPUS or Publisher's site
Abstract CoFe2O4/multiwalled carbon nanotubes (MWCNTs) hybrid materials were synthesized by a hydrothermal method. Field emission scanning electron microscopy and transmission electron microscopy analysis confirmed the morphology of the as-prepared hybrid material resembling wintersweet flower âbuds on branchesâ, in which CoFe2O4 nanoclusters, consisting of nanocrystals with a size of 5â10ânm, are anchored along carbon nanotubes. When applied as an anode material in lithium ion batteries, the CoFe2O4/MWCNTs hybrid material exhibited a high performance for reversible lithium storage. In particular, the hybrid anode material delivered reversible lithium storage capacities of 809, 765, 539, and 359âmAâhâgâ1 at current densities of 180, 450, 900, and 1800âmAâgâ1, respectively. The superior performance of CoFe2O4/MWCNTs hybrid materials could be ascribed to the synergistic pinning effect of the wintersweet-flower-like nanoarchitecture. This strategy could also be applied to synthesize other metal oxide/CNTs hybrid materials as high-capacity anode materials for lithium ion batteries.
Mondal, AK, Wang, B, Su, D, Wang, Y, Zhang, X & Wang, G 2012, 'Preparation and enhanced electrochemical performance of MnO2 nanosheets for supercapacitors', Journal of the Chinese Chemical Society, vol. 59, pp. 1275-1279.View/Download from: UTS OPUS or Publisher's site
MnO2 nanosheets have been synthesized by using a redox reaction of manganese nitrate tetrahydrate and potassium permanganate without any surfactants. The morphology and microstructure of the as-prepared material were characterized by field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction (XRD). Electrochemical performances as electrode materials for supercapacitor were evaluated using cyclic voltammetry and galvanostatic charge-discharge in 1 M Na2SO4 aqueous electrolyte. It was found that MnO2 nanosheets showed an excellent capacitive behaviour with good cycling stability. The specific capacitance of the MnO2 nanosheet electrode can reach up to 332.8 Fgâ1 at a current density of 500 mA/g and a stable cycling performance.
Wang, Y, Sun, B, Park, J, Kim, W, Kim, H & Wang, G 2011, 'Morphology control and electrochemical properties of nanosize LiFePO4 cathode material synthesized by co-precipitation combined with in situ polymerization', Journal Of Alloys And Compounds, vol. 509, no. 3, pp. 1040-1044.View/Download from: UTS OPUS or Publisher's site
Nanosize carbon coated LiFePO4 cathode material was synthesized by in situ polymerization. The as-prepared LiFePO4 cathode material was systematically characterized by X-ray diffraction, thermogravimetric-differential scanning calorimetry, X-ray photo-electron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy techniques. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images revealed that the morphology of the LiFePO4 consists of primary particles (40-50 nm) and agglomerated secondary particles (100-110 nm). Each particle is evenly coated with an amorphous carbon layer, which has a thickness around 3-5 nm. The electrochemical properties were examined by cyclic voltammetry and charge-discharge testing. The as-prepared LiFePO4 can deliver an initial discharge capacity of 145 mAh/g, 150 mAh/g, and 134 mAh/g at 0.2 C, 1 C, and 2 C rates, respectively, and exhibits excellent cycling stability. At a higher C-rate (5 C) a slight capacity loss could be found. However after being charge-discharge at lower C-rates, LiFePO4 can be regenerated and deliver the discharge capacity of 145 mAh/g at 0.2 C. (C) 2010 Elsevier B.V. All rights reserved.
Wang, B, Wang, Y, Park, J, Ahn, H & Wang, G 2011, 'In situ synthesis of Co(3)O(4)/graphene nanocomposite material for lithium-ion batteries and supercapacitors with high capacity and supercapacitance', Journal Of Alloys And Compounds, vol. 509, no. 29, pp. 7778-7783.View/Download from: UTS OPUS or Publisher's site
Abstract: Co(3)O(4)/graphene nanocomposite material was prepared by an in situ solution-based method under reflux conditions. In this reaction progress, Co(2+) salts were converted to Co(3)O(4) nanoparticles which were simultaneously inserted into the graphene layers, upon the reduction of graphite oxide to graphene. The prepared material consists of uniform Co(3)O(4) nanoparticles (15-25 nm), which are well dispersed on the surfaces of graphene nanosheets. This has been confirmed through observations by field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The prepared composite material exhibits an initial reversible lithium storage capacity of 722 mAh g(-1) in lithium-ion cells and a specific supercapacitance of 478 F g(-1) in 2 M KOH electrolyte for supercapacitors, which were higher than that of the previously reported pure graphene nanosheets and Co(3)O(4) nanoparticles. Co(3)O(4)/graphene nanocomposite material demonstrated an excellent electrochemical performance as an anode material for reversible lithium storage in lithium ion cells and as an electrode material in supercapacitors. (C) 2011 Elsevier B.V. All rights reserved.
Wang, G, Wang, B, Park, J, Wang, Y, Sun, B & Yao, J 2009, 'Highly efficient and large-scale synthesis of graphene by electrolytic exfoliation', Carbon, vol. 47, no. 14, pp. 3242-3246.View/Download from: UTS OPUS or Publisher's site
Highly efficient and large-scale synthesis of graphene from graphite was produced by electrolytic exfoliation using poly(sodium-4-styrenesulfonate) as an effective electrolyte. Scanning and transmission electron microscopy, and atomic force microscopy confirmed the existence of monolayer graphene sheets and stacks containing a few graphene sheets. Raman spectroscopy demonstrated that the as-prepared graphene sheets have low defect content. Based on the measurement of FTIR spectra, the edge-to-face interaction (?? interaction) between the graphene surface and aromatic rings of poly(sodium-4-styrenesulfonate) could be primarily responsible for producing exfoliation of the graphite electrode to graphene during electrolysis. In contrast to micromechanical exfoliation, electrolytic exfoliation can be scaled up for large-scale and continuous graphene production.