Electrochemical Characterizations and Structure of Li_(0.99)Na_(0.01)FePO_4/C as Cathode Material for Li-ion Battery

In order to improve the rate performance of lithium iron phosphate,Na+ doped LiFePO4/C cathode ma-terials 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 sam-ples 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 cy-cling performance and rate capability effectively.Compared with LiFePO4/C,Li0.99Na0.01FePO4/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,respec-tively.In addition,it has excellent cycle stability at different rates and good performance.