In order to improve the rate performance of lithium iron phosphate, Na+ doped LiFePCVC cathode materials were prepared by carbothermal reduction technology. Samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transfer infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Their electrochemical performances were investigated by galvanostatic charge/discharge in terms of cycling performance and rate capability. The results show that the samples have well regulated olivine type structures without any impurity peaks. Na-doping improves the conductivity and the Li+ diffusion rate of composite materials and decreases the polarization of electrode, and enhances the cycling performance and rate capability effectively. Compared with LiFePCVC, Li0.99Na0.01iFePO4/C exhibits good electrode properties with discharge capacities of 147.6, 126.4 and 105.1 mAh/g at 0.5C, 2.0C and 5C rates, respectively. In addition, it has excellent cycle stability at different rates and good performance.%为了提高LiFePO4的倍率性能,用碳热还原法制备了Na+掺杂的LiFePO4/C复合正极材料,并用X射线衍射(XRD)、扫描电子显微镜(SEM)、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Na+掺杂对LiFePO4/C材料的结构、微观形貌和电化学性能的影响.结果表明,Na+掺杂的LiFePO4/C复合材料具有单一的橄榄石型晶体结构,不存在杂质衍射峰,Na+在Li位掺杂可提高材料的导电性能和Li+扩散速率,降低电极极化,能有效改善材料的循环性能和倍率性能.与LiFePO4/C相比,Li0.99Na0.01FePO4/C的0.5C、2C和5C放电比容量分别为147.6、126.4和105.1 mAh/g,并表现出良好的循环性能和倍率性能.
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