Effects of different iron sources on the performance of LiFePO4/C composite cathode materials

Olivine LiFePO4/C composite cathode materials were synthesized by a solid state method in N2 + 5vol% H2 atmosphere. The effects of different iron sources, including Fe(OH)3 and FeC2O4·2H2O, on the performance of as-synthesized cathode materials were investigated and the causes were also analyzed. The crystal structure, the morphology, and the electrochemical performance of the prepared samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), laser particle-size distribution measurement, and other electrochemical techniques. The results demonstrate that the LiFePO4/C materials obtained from Fe(OH)3 at 800°C and FeC2O4·2H2O at 700°C have the similar electrochemical performances. The initial discharge capacities of LiFePO4/C synthesized from Fe(OH)3 and FeC2O4·2H2O are 134.5 mAh·g−1 and 137.4 mAh·g−1 at the C/5 rate, respectively. However, the tap density of the LiFePO4/C materials obtained from Fe(OH)3 are higher, which is significant for the improvement of the capacity of the battery.