新型正极材料LiFePO4的电化学性能的改进

为解决锂离子蓄电池新型正极材料LiFePO4的低导电率的问题,采用高温固相法合成出包覆碳并掺杂了少量Mg2 的LiFePO4样品。采用X射线衍射、充放电测试、交流阻抗和循环伏安测试方法,深入研究了包覆碳后Mg2 掺杂对LiFePO4结构和电化学性能的影响。研究结果表明,包覆碳后掺杂少量的Mg2 能进一步提高LiFePO4的导电性,从而提高材料的比容量和循环性能。不同的Mg2 离子掺杂量(x=0.02、0.04、0.06、0.08)里,Li0.94Mg0.06FePO4的电化学性能最佳,以0.1C充放电,首次放电比容量为141.9mAh/g,充放电效率为93.1%;循环50次后,容量几乎没有衰减。

Improvement of electrochemical performance of LiFePO4 as a novel cathode material

To solve the problem of low conductivity in LiFePO4 as novel cathode material for lithium ion battery,a small quantity of Mg2 -doped and carbon-coated LiFePO4 samples have been prepared by high temperature solid-state reaction method.The effect on the structure and electrochemical performance of carbon-coated LiFePO4 by Mg2 ion doping was investigated intensively by X-ray diffraction,charge-discharge tests,alternating current impedance and cyclic voltammetry method.The results show that the conductivity of carbon-coated LiFePO4 is improved by Mg2 ion doping,so the capacity and cycle performance of the material are increased.In the different amounts of doping Mg2 ion(x=0.02,0.04,0.06,0.08),the electrochemical performance of Li0.94Mg0.06FePO4 is the best.As Li0.94Mg0.06FePO4 is charged and discharged at 0.1C,its first specific discharge capacity and charge-discharge efficiency are 141.9 mAh/g and 93.1% respectively.After 50 cycles,its capacity has no decay.