Influence of Sintering Atmosphere on the Physical and Electrochemical of LiFePO<sub>4</sub>/C

LiFePO 4 /C was synthesized from a gel precursor with ferric iron and an organic chelating agent as carbon source. Reductive atmosphere of N 2 + H 2 with H 2 content of 0-20 vol % was used in the sintering process of LiFePO 4 /C composites. The microstructures of the obtained LiFePO 4 /C particles were characterized by X-ray diffraction, field emission scanning electron microscopy, element analysis and particle size analysis. The results showed that suitable reductive sintering atmosphere was needed to get pure LiFePO 4 /C phase, but too strong reducibility led to the formation of iron phosphides, most of which was Fe 2 P. The amount of Fe 2 P increased with the increase of H 2 content in the sintering atmosphere. The rate capability of LiFePO 4 /C was improved when the sintering atmosphere became more reductive, while the discharge capacity of 0.1C decreased, which was probably due to the appearance of Fe 2 P phase.