Li2FeSiO4 is deemed to be a potential candidate for large-scale applications because of its abundance,low cost and high safety,etc.Unfortunately,its low conductivity,resulting in poor rate performance,has become a mai...Li2FeSiO4 is deemed to be a potential candidate for large-scale applications because of its abundance,low cost and high safety,etc.Unfortunately,its low conductivity,resulting in poor rate performance,has become a main obstacle to its applications in power battery and energy storage system.In this work,C-Ag coated Li2FeSiO4 is introduced to improve the innate electronic conductivity and Li-ion diffusion ability.The results demonstrate that Li2FeSiO4/C/Ag composite exhibits better electrochemical performance.It possesses a specific discharge capacity of 152,121,108 mA.h/g at 0.2C,5C and 10C,respectively.At the same time,the Li2FeSiO4/C/Ag composite shows good cycle stability and a capacity retention ratio of 97.9%after 100 cycles at 1C.展开更多
Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization...Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization. The amount of carbon in the composite is less than 10% （mass fraction）, and the X-ray diffraction result confirms that the sample is of pure single phase indexed with the orthorhombic Pmn21 space group. The particle size of the Li2FeSiO4/C synthesized at 700 °C for 9 h is very fine and spherical-like with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, were tested. The cell of this sample can deliver a discharge capacity of 166 mA-h/g at C/20 rate in the first three cycles. After 30 cycles, the capacity decreases to 158 mA-h/g, and the capacity retention is up to 95%. The results show that this method can prepare nanosphere-like Li2FeSiO4/C composite with good electrochemical performance.展开更多
Li2SiO3 was synthesized by combination of sol-gel method and calcination at high temperature using Li2CO3, HNO3, Si（OC2H5）4 and C2H5OH as starting materials. The effects of calcination temperature and refluxing syst...Li2SiO3 was synthesized by combination of sol-gel method and calcination at high temperature using Li2CO3, HNO3, Si（OC2H5）4 and C2H5OH as starting materials. The effects of calcination temperature and refluxing system on the composition and properties of lithium silicate were investigated. The samples were characterized by TGA/DTA, XRD, SEM and particle size analysis. Li2FeSiO4 was prepared by the solid-state reaction between Li2SiO3 and FeC2O4·2H2O. The XRD patterns show that the use of refluxing system in the sol-gel preparation can decrease the Li2Si2O5 and Li4SiO4 impurities in the Li2SiO3 sample. The calcination temperature plays an important role in the properties of the Li2SiO3 samples. The sample calcined at 700 °C has high purity of 97% Li2SiO3 and good morphology as precursor of Li2FeSiO4. It consists of primary particles with size of 1-3 μm, and the primary particle clusters form agglomerates with loose and porous appearance.展开更多
A novel synthetic method of microwave processing to prepare Li2FeSiO4 cathode materials is adopted. The Li2FeSiO4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing. Olivin-typ...A novel synthetic method of microwave processing to prepare Li2FeSiO4 cathode materials is adopted. The Li2FeSiO4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing. Olivin-type Li2FeSiO4 sample with uniform and fine particle sizes is successfully and fast synthesized by microwave heating at 700 ℃ in 12 rain. And the obtained Li2FeSiO4 materials show better electrochemical performance and microstructure than those of Li2FeSiO4 sample by the conventional solidstate reaction. ？2009 Yan Bing Cao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
In this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2F...In this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2FeSi04 was synthesized by a facile hydrothermal method with（NH4）2Fe（SO4）2 as the iron source.The spindle-like Li2FeSiO4 was sintered at 600 ℃ for 6 h in Ar atmosphere.Li2FeSiO4-C composite was obtained by the hydrothermal treatment of spindle-like Li2FeSiO4 in glucose solution at 190 ℃ for 3 h.Electrochemical measurements show that after carbon coating,the electrode performances such as discharge capacity and high-rate capability are greatly enhanced.In particular.Li2FeSiO4-C with carbon content of 7.21 wt%delivers the discharge capacities of 160.9 mAh·g-1 at room temperature and 213 mAh·g-1 at45℃（0.1 C）,revealing the potential application in lithium-ion batteries.展开更多
A Li2FeSiO4/C composite cathode for lithium ion batteries was synthesized at 650 ℃ by solid-state reaction. The effects of carbon sources and carbon content on the properties of the Li2FeSiO4/C composites were invest...A Li2FeSiO4/C composite cathode for lithium ion batteries was synthesized at 650 ℃ by solid-state reaction. The effects of carbon sources and carbon content on the properties of the Li2FeSiO4/C composites were investigated. The crystalline structure, morphology, carbon content and charge/discharge performance of Li2FeSiO4/C composites were determined by X-ray diffraction(XRD), scanning electron microscopy(SEM), carbon/sulfur analyzer and electrochemical measurements. As carbon content increases in the range of 5%?20%, the amount of Fe3O4 impurity phase decreases. The SEM micrographs show that the addition of the carbon is favorable for reducing the Li2FeSiO4 grain size. Using sucrose as carbon source, the Li2FeSiO4/C composite with 14.5% carbon synthesized at 650 ℃ shows good electrochemical performance with an initial discharge capacity of 144.8 mA·h/g and a capacity retention ratio of 94.27% after 13 cycles.展开更多
基金Project(21771062)supported by the National Natural Science Foundation of ChinaProject(2016JJ2092)supported by the Hunan Provincial Natural Science Foundation,ChinaProject(2019013)supported by the Open Project Program of Key Laboratory of Preparation and Application of Environmental Friendly Materials,Ministry of Education,Jilin Normal University,China
文摘Li2FeSiO4 is deemed to be a potential candidate for large-scale applications because of its abundance,low cost and high safety,etc.Unfortunately,its low conductivity,resulting in poor rate performance,has become a main obstacle to its applications in power battery and energy storage system.In this work,C-Ag coated Li2FeSiO4 is introduced to improve the innate electronic conductivity and Li-ion diffusion ability.The results demonstrate that Li2FeSiO4/C/Ag composite exhibits better electrochemical performance.It possesses a specific discharge capacity of 152,121,108 mA.h/g at 0.2C,5C and 10C,respectively.At the same time,the Li2FeSiO4/C/Ag composite shows good cycle stability and a capacity retention ratio of 97.9%after 100 cycles at 1C.
基金Project supported by Ministry of Education Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, China Project (2010JK765) supported by the Education Department of Shaanxi Province, China
文摘Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization. The amount of carbon in the composite is less than 10% （mass fraction）, and the X-ray diffraction result confirms that the sample is of pure single phase indexed with the orthorhombic Pmn21 space group. The particle size of the Li2FeSiO4/C synthesized at 700 °C for 9 h is very fine and spherical-like with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, were tested. The cell of this sample can deliver a discharge capacity of 166 mA-h/g at C/20 rate in the first three cycles. After 30 cycles, the capacity decreases to 158 mA-h/g, and the capacity retention is up to 95%. The results show that this method can prepare nanosphere-like Li2FeSiO4/C composite with good electrochemical performance.
基金Foundation item: Project (2007CB613607) support by the National Basic Research Program of ChinaProject (2010QZZD0101) supported by the Basic Research Foundation for the Chinese Central Universities
文摘Li2SiO3 was synthesized by combination of sol-gel method and calcination at high temperature using Li2CO3, HNO3, Si（OC2H5）4 and C2H5OH as starting materials. The effects of calcination temperature and refluxing system on the composition and properties of lithium silicate were investigated. The samples were characterized by TGA/DTA, XRD, SEM and particle size analysis. Li2FeSiO4 was prepared by the solid-state reaction between Li2SiO3 and FeC2O4·2H2O. The XRD patterns show that the use of refluxing system in the sol-gel preparation can decrease the Li2Si2O5 and Li4SiO4 impurities in the Li2SiO3 sample. The calcination temperature plays an important role in the properties of the Li2SiO3 samples. The sample calcined at 700 °C has high purity of 97% Li2SiO3 and good morphology as precursor of Li2FeSiO4. It consists of primary particles with size of 1-3 μm, and the primary particle clusters form agglomerates with loose and porous appearance.
基金supported by National Key Technology R&D Program of China(No.2007BAE12B01-1)Science and Technology Planning Program of Hunan Province,China(No.2008GK3015)
文摘A novel synthetic method of microwave processing to prepare Li2FeSiO4 cathode materials is adopted. The Li2FeSiO4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing. Olivin-type Li2FeSiO4 sample with uniform and fine particle sizes is successfully and fast synthesized by microwave heating at 700 ℃ in 12 rain. And the obtained Li2FeSiO4 materials show better electrochemical performance and microstructure than those of Li2FeSiO4 sample by the conventional solidstate reaction. ？2009 Yan Bing Cao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金supported by the Programs of National 973(2011CB935900)NSFC(21231005)+1 种基金MOE(B12015 and 113016A)the Fundamental Research Funds for the Central Universities
文摘In this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2FeSi04 was synthesized by a facile hydrothermal method with（NH4）2Fe（SO4）2 as the iron source.The spindle-like Li2FeSiO4 was sintered at 600 ℃ for 6 h in Ar atmosphere.Li2FeSiO4-C composite was obtained by the hydrothermal treatment of spindle-like Li2FeSiO4 in glucose solution at 190 ℃ for 3 h.Electrochemical measurements show that after carbon coating,the electrode performances such as discharge capacity and high-rate capability are greatly enhanced.In particular.Li2FeSiO4-C with carbon content of 7.21 wt%delivers the discharge capacities of 160.9 mAh·g-1 at room temperature and 213 mAh·g-1 at45℃（0.1 C）,revealing the potential application in lithium-ion batteries.
基金Project(2007CB613607) supported by the National Basic Research Program of China
文摘A Li2FeSiO4/C composite cathode for lithium ion batteries was synthesized at 650 ℃ by solid-state reaction. The effects of carbon sources and carbon content on the properties of the Li2FeSiO4/C composites were investigated. The crystalline structure, morphology, carbon content and charge/discharge performance of Li2FeSiO4/C composites were determined by X-ray diffraction(XRD), scanning electron microscopy(SEM), carbon/sulfur analyzer and electrochemical measurements. As carbon content increases in the range of 5%?20%, the amount of Fe3O4 impurity phase decreases. The SEM micrographs show that the addition of the carbon is favorable for reducing the Li2FeSiO4 grain size. Using sucrose as carbon source, the Li2FeSiO4/C composite with 14.5% carbon synthesized at 650 ℃ shows good electrochemical performance with an initial discharge capacity of 144.8 mA·h/g and a capacity retention ratio of 94.27% after 13 cycles.
