Co^(2+)掺杂对磷酸钒锂电化学性能的影响

Effects of doping Co^(2+) on the electrochemical performance of Li_3V_2(PO_4)_3

用XRD、透射电镜(TME)和电化学性能测试,研究了Co2+掺杂对正极材料磷酸钒锂[Li3V2(PO4)3]的影响。掺杂适量的Co2+不会改变Li3V2(PO4)3的单斜晶系结构,可稳定材料结构,改善高倍率充放电性能。在室温下、3.0～4.3 V充放电,Li3(Co0.03V0.97)2(PO4)3以0.1C放电的首次放电比容量为116.8 mAh/g,电流从0.1C增加到1.0C循环80次后,容量衰减率为16.5%;Li3V2(PO4)3的首次放电比容量为128.8mAh/g,80次循环后,容量衰减率为34.8%。循环伏安和交流阻抗测试表明:Li3(Co0.03V0.97)2(PO4)3的可逆性优于Li3V2(PO4)3。

Abstract： The effects of doping Co^2＋ on cathode material lithium vanadium phosphate[ LisV2 （PO4）3 ] were studied by XRD, transmission electron microscopy（TEM） and electrochemical performance test. The monoclinic structure of Li3 V2 （ POt ）3 would not change, the structure was more stable,the high rate charge-discharge performance was improved. While charged-discharged in 3.0 - 4.3 V under room temperature, the initial specific capacity of Li3（ Co0.03 V0.97）2（ PO4）3 was 116.8 mAh/g at 0. l C discharge, the capacity fading rate was 16.5% after 80 cycles with the current increased from 0.1 C to 1.0 C. The initial specific discharge capacity of Li3V2（PO4）3 was 128.SmAh/g and the capacity fading rate was 34.8% after 80 cycles. The test of cyclic voltammo- gram and AC impedance showed that the reversibility of Li3（Co0.03V0.97）2（PO4）3 was better than that of Li3V2（PO4）3.