Synthesis of LiFePO4/C with Fe3O4 as Iron Source by High Temperature Ball Milling

LiFePO4/C cathode material was prepared with Fe3O4 as iron source by a high temperature ball milling (HTBM) method and the effects of milling temperature were experimentally investigated in this work. The results indicated that high milling temperature improved the crystallinity of LiFePO4, but that an unfavorable crystal agglomeration and the phase transformation from LiFePO4 into LiFeP2O7 could occur when the temperature becomes too high. LiFePO4/C synthesized by HTBM at 650 degrees C exhibited the optimal electrochemical performance: the initial discharge capacities were 152.7, 146.6, 140.3, 130.0, 119.1 and 108.3 mAhg(-1) at rates of 0.5, 1.0, 2.0, 5.0 and 10C, respectively; after 50 cycles, the capacities of LiFePO4/C sample were 147.0, 135.0, 126.4, 115.4, 105.6 and 95.3 at rates of 0.1, 0.5, 1.0, 2.0, 5.0 and 10C, and their capacity retention were 96.3%, 92.1%, 90.0%, 88.8%, 88.7% and 88.1%, respectively. No obvious capacity decay was observed demonstrating the excellent electrochemical performance of the product prepared by this work.