碳含量对LVP/C材料电化学性能的影响

Effect of carbon content on electrochemical performance of LVP/C

为改善磷酸钒锂的导电性能,以柠檬酸为碳源,采用溶胶凝胶法合成碳包覆磷酸钒锂(LVP/C)复合材料。通过充放电性能测试、循环伏安测试、XRD、SEM等分析手段,探讨碳含量对复合材料电化学性能的影响。结果表明:碳源加入摩尔比为2.0时所制得的LVP/C材料电化学性能最好。在电压3.0~4.3 V、0.5倍率的条件下,C2.0材料首次放电比容量可达123 m Ah/g,循环80周后,相对于第一周循环充放电容量,比容量保持率为99.7%,材料的可逆性和锂离子扩散性能最好。结构和形貌表征显示样品结晶性能良好,晶粒大小约1μm,碳层厚度约为3.6 nm。

This paper is directed at improving the conductivity of LVP. The targeted research process involves synthesizing carbon-coated lithium vanadium phosphate（ LVP/C） composite from citric acid as the carbon source using sol-gel method and investigating the effect of carbon content on the electrochemical performance in LVP/C through charge-discharge,CV,XRD and SEM. The results show that LVP/C fabricated by adding a mole ratio of 2. 0 to the carbon source exhibits the best electrochemical performance; when working at the voltage ranging from 3. 0-4. 3 V,and rate of 0. 5,C2. 0 material has the initial discharge specific capacity of up to 123 m Ah/g and,after 80 cycles,it exhibits the specific capacity retention rate of 99. 7%,relative to the first-cycle charge-discharge capacity,demonstrating the best reversible and lithium ion diffusion performance; and the samples boast the better crystalline properties： the crystalline grain size of about 1 μm and coated carbon thickness of about 3. 6 nm,as is validated by the characterization of structure and morphology.