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
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.
