Synthesis and Electrochemical Properties of LiFeP0.95B0.05O4-δ/C Cathode Materials

B-doped LiFePO4 in P-site, LiFeP0.95B0.05O4-delta/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-delta/C synthesized at 650 degrees C 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.