Synthesis and Electrochemical Properties of LiFeP_(0.95)B_(0.05)O_(4-δ)/C Cathode Materials

B-doped LiFePO4 in P-site,LiFeP0.95B0.05O 4-δ/C composite materials were synthesized in flowing Ar atmosphere by sol-gel method,using citric acid as chelating agent and carbon source.Samples were characterized by X-ray diffraction and cyclic voltammetry,and their electrochemical performances were investigated by galvanostatic charge/discharge tests in terms of cycling performance and rate capability.The results show that the samples have well-regulated olivine-type structures without any impurity peaks while B-doping improves the conductivity of composite materials and decreases the polarization of electrode,and enhances the cycling performance and rate capability effectively.The discharge capacities of LiFeP0.95B0.05O4-δ/C synthesized at 650℃ are 149.3,123.4 and 112.1 mAh/g at the rates of 0.2C,5C and 10C,with retention ratio of 99.3% after 20 cycles at the rate of 0.2C,91.65% after 150 cycles at the rate of 5C and 92.9% after 150 cycles at the rate of 10C,respectively.After continuous 30 cycles at different rates of 0.2,1,3,5 and 10C,the discharge capacity of 0.2C can reconvert to the previous value.