Synthesis of Sub-micrometer Lithium Iron Phosphate Particles for Lithium Ion Battery by Using Supercritical Hydrothermal Method

Abstract

A supercritical hydrothermal method was employed to prepare sub-micrometer LiFePO4 particles with high purity and crystallinity. The structure and morphology of LiFePO4 particles were characterized by X-ray diffraction and scanning electron microscope. The electrochemical tests were carried out to determine the reversible capacity, rate and cycling performance of the LiFePO4 particles as cathode material for lithium ion battery. Experimental results show that solvent and calcining time have significant effects on purity, size and morphology of LiFePO4 particles. Mixed solvent contained deionized water and ethanol is conducive to synthesize smaller and more uniform particles. The size of LiFePO4 particles as-prepared is about 100-300 nm. The specific discharge capacities of the LiFePO4 particles are 151.3 and 128.0 mA·h·g−1 after first cycle at the rates of 0.1 and 1.0 C, respectively. It retains 95.0% of the initial capacity after 100 cycles at 1.0 C.