Dehydration of FePO4•2H2O for the Synthesis of LiFePO4/C: Effect of Dehydration Temperature

To study the effect of dehydration temperature on synthesis and electrochemical performance of LiFePO4/C, FePO4 center dot 2H(2)O is dehydrated at different temperatures (200-700 degrees C) and the resulting FePO4 is adopted as a raw material to synthesize LiFePO4/C composite. The results show that FePO4 center dot 2H(2)O can be fully dehydrated at a temperature above 184 degrees C, the crystalline form, particle size and morphology of the dehydrated FePO4 varies with dehydration temperature, and the synthesized LiFePO4/C composites from these FePO4 have similar crystallinity, particle size and morphology, but have different electrochemical performance. Among all samples, the LiFePO4/C synthesized from the FePO4 dehydrated at 500 degrees C exhibits the best electrochemical performance. From these results, it is suggested that alpha-quartz FePO4 with a trigonal structure (P3(1)21) is an optimum form for efficient synthesis of high performance LiFePO4/C composite, and the dehydration of FePO4 center dot 2H(2)O should be controlled at a temperature around 500 degrees C.