Phase Transition of Bare and Coated LixCoO2 (x = 0.4 and 0.24) at 300 ° C

Abstract

The phase transitions of the bare and -coated delithiated ( and 0.24) according to the coating concentration (thickness) after heat-treatment at was investigated using nuclear magnetic resonance and X-ray absorption spectra. It was found that the bare and coated predominantly decomposed into spinel or phases depending on the charging voltage. As the charging voltage was increased from , the bare and -coated decomposed into the phase while the -coated sample decomposed into the phase. The improvement in the thermal stability of the -coated , compared to the bare and -coated samples, could be explained by the dominant local formation of the phase over the phase.