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
Flower-like CuO and flower-like CuO/graphene composite were prepared successfully by hydrothermal method. They were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, temperature-pr...Flower-like CuO and flower-like CuO/graphene composite were prepared successfully by hydrothermal method. They were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, temperature-programmed reduction, and thermogravimetric analysis. It is found that the flower-like CuO microspheres, which are composed of CuO nanosheets, possess an average diameter of 4.2 μm and a Brunauer–Emmett–Teller surface area of 12.6 m2/g. Compared with the flower-like CuO, the obtained flower-like CuO/graphene composite shows an enhanced electrochemical performance with a higher capacity of 603 mA-h/g at 0.1 C rate and 382 mA-h/g at 1 C rate, and exhibits a better cycle stability with a high capacity retention of 95.5 % after 50 cycles even though at 1 C rate.展开更多
采用高温固相反应方法合成锂离子电池正极Li_2Fe_(1-x-y)Mn_xNi_ySiO_4/C复合材料,并采用X-ray线衍射、扫描电子显微镜和电化学分析方法,研究了Ni和Mn离子共掺杂及碳修饰复合改性对复合材料结构和性能的影响。结果表明,复合改性没有对...采用高温固相反应方法合成锂离子电池正极Li_2Fe_(1-x-y)Mn_xNi_ySiO_4/C复合材料,并采用X-ray线衍射、扫描电子显微镜和电化学分析方法,研究了Ni和Mn离子共掺杂及碳修饰复合改性对复合材料结构和性能的影响。结果表明,复合改性没有对材料的晶体结构造成改变,镍锰离子共掺杂和表面碳包覆能有效提高材料的比容量和循环性能;以C/32倍率充放电,复合掺杂得到的Li_2Fe_(0.6)Mn_(0.2)Ni_(0.2)SiO_4/C材料样品的电化学性能最优,根据实测结果,该复合材料的首次放电比容量达到149 m Ah·g^(-1),充放电循环10次以后容量保持率仍有95.3%。展开更多
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.
基金Project (20110490594) supported by China Postdoctoral Science Foundation
文摘Flower-like CuO and flower-like CuO/graphene composite were prepared successfully by hydrothermal method. They were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, temperature-programmed reduction, and thermogravimetric analysis. It is found that the flower-like CuO microspheres, which are composed of CuO nanosheets, possess an average diameter of 4.2 μm and a Brunauer–Emmett–Teller surface area of 12.6 m2/g. Compared with the flower-like CuO, the obtained flower-like CuO/graphene composite shows an enhanced electrochemical performance with a higher capacity of 603 mA-h/g at 0.1 C rate and 382 mA-h/g at 1 C rate, and exhibits a better cycle stability with a high capacity retention of 95.5 % after 50 cycles even though at 1 C rate.
文摘采用高温固相反应方法合成锂离子电池正极Li_2Fe_(1-x-y)Mn_xNi_ySiO_4/C复合材料,并采用X-ray线衍射、扫描电子显微镜和电化学分析方法,研究了Ni和Mn离子共掺杂及碳修饰复合改性对复合材料结构和性能的影响。结果表明,复合改性没有对材料的晶体结构造成改变,镍锰离子共掺杂和表面碳包覆能有效提高材料的比容量和循环性能;以C/32倍率充放电,复合掺杂得到的Li_2Fe_(0.6)Mn_(0.2)Ni_(0.2)SiO_4/C材料样品的电化学性能最优,根据实测结果,该复合材料的首次放电比容量达到149 m Ah·g^(-1),充放电循环10次以后容量保持率仍有95.3%。
