中文摘要：

为了提高LiFePO4的倍率性能,用碳热还原法制备了LiFePO4-xFx/C复合正极材料,并用X射线衍射（XRD）、红外光谱（FT-IR）、恒电流充放电技术、循环伏安（CV）和交流阻抗（EIS）研究了F-掺杂和碳包覆对材料的结构和电化学性能的影响。研究表明,掺杂少量的F-可以减少电极极化、降低电荷转移电阻、增大Li＋的扩散速率。其中LiFePO3.99F0.01/C的5C放电比容量为109.9mAh/g,50次循环后仍保持110.6mAh/g,表现出良好的倍率性能。

英文摘要：

LiFePO4 has been studied intensively as a potential cathode material for rechargeable Li-ion batteries.However,poor rate performance limits its commercial application.In our work,LiFePO4-xFx/C composite cathode materials were prepared by carbothermal reduction technology to improve its rate performance.The crystalline structure,morphology and electrochemical performances of the samples were characterized by X-ray diffraction（XRD）,Fourier transfer infrared spectroscopy（FT-IR）,charge-discharge experiments,cyclic voltammetry（C-V） and electrochemical impedance spectroscopy（EIS）.The results showed that doping with F-can reduce the electrochemical polarization and the resistance of charge transfer,and improve lithium ion diffusion rate,which improve the rate capability of cathode material.Among these composite cathode materials,LiFePO3.99F0.01/C delivered a discharge capacities of 109.9 and 110.6mAh/g after 50 cycles at 5C and exhibited good rate performance.