关键词: 锂离子电池, LiMnPO₄橄榄石, 正极材料, 合成, 电化学性能

Abstract: Olivine LiMnPO4 was synthesized at 600 ℃ and 800 ℃ by the method of solid-state reaction combining with the addition of carbon black and ball-milling of reagents and precursors. Structure, surface morphology and charge/discharge performance of LiMnPO4 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical measurement, respectively. Sample synthesized at 600 ℃ by ball-milling of reagents for 24 h and precursors for 12 h contains impurities and large, densely sintered blocks .Pure olivine LiMnPO4 with large particle size is obtained at 800 ℃ by the same ball-milling process. It is shown that these materials can′t charge or discharge effectively in the electrochemical tests. On the contrary, sample prepared at 600 ℃ by ball-milling of reagents for 36 h and precursors for 24 h presents pure phase with small and almost identical particles size (about 100～200 nm). The initial discharge capacity of this sample is approximately 100 mAh•g－1. Mixing of the agents and the precursors and the choice of sintering temperature are two important factors to obtain pure olivine LiMnPO4 with reversible charge-discharge capacity.

Key words: Lithium ion batteries, LiMnPO₄, Olivine, Cathode materials, Synthesis, Electrochemical performance