Preparation and characterization of LiMn_1.8Co_0.2O_3.95F_0.05 by the combustion-assisted soft route

Abstract

LiMn_1.8Co_0.2O_3.95F_0.05 powder was prepared by heating the ignited LiMn_1.8 Co_0.2 O_3.95 F_0.05 precursor gel using lithium acetate, magnesium acetate, cobalt acetate, lithium fluoride, citric acid and glycol as raw materials. The influence of the calcination temperature on the structural and electrochemical properties of LiMn_1.8 Co_0.2 O_3.95 F_0.05 was investigated by X-ray diffraction, scanning electron microscopy, and galvanostatic charge-discharge experiments. The powders prepared under different conditions are of good crystallinity. The discharge capacity of LiMn_1.8 Co_0.2 O_3.95 F_0.05 powder increased from 92 mAh/g to 105 mAh/g as the calcination temperature increased from 750 °C to 850 °C. The capacity of LiMn_1.8 Co_0.2 O_3.95 F_0.05 heated at 750 °C, 800 °C, 850 °C for 4 hours remained at 95.2%, 97%, 94.2%, respectively, after being cycled 20 times, suggesting that the multiple substitution of Co and F for Mn and O results in a good cycling behavior.

Keywords

lithium ion / X-ray diffraction / spinel / electrochemical properties

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