关键词: 磷酸铁锂, 一氧化碳还原, 高温原位XRD, Li3Fe2(PO4)3, 机理, 动力学

Abstract: LiFePO4 cathode material was synthesized by CO reducing FePO4 and LiOH precursors.The structure,morphology and electrochemical performances of such LiFePO4 material were characterized by XRD,SEM and charge-discharge tests.It was shown that the particle size of the LiFePO4 synthesized with 5% excess of LiOH in the precursor was about 200 nm.By carbon coating,the LiFePO4 electrode was able to deliver a reversible capacity of 158 mAh·g-1 at 0.1C discharge rate.Temperature-programmed X-ray diffraction was employed to monitor the reaction during the formation of LiFePO4,and Li3Fe2(PO4)3 was found to be an intermediate by analyzing the time-resolved XRD patterns.Kinetic study indicates that nucleation and their growth is the rate-determining step in the process of the reaction and the activation energy of this reaction was 89.44 kJ/mol.

Key words: LiFePO4, CO reduction, temperature-programmed X-ray diffraction, Li3Fe2(PO4)3, mechanism, kinetics