Enhanced high-potential and elevated-temperature cycling stability of cathode by TiO{sub}2 modification for Li-ion battery

摘要

The surface of spinel LiMn{sub}2O{sub}4 was modified with TiO{sub}2 by a simple sol-gel method to improve its electrochemical performance at elevated temperatures and higher working potentials. Compared with pristine LiMn{sub}2O{sub}4, surface-modification improved the cycling stability of the material. The capacity retention of TiO{sub}2-modified LiMn{sub}2O{sub}4 was more than 85% after 60 cycles at high potential cycles between 3.0 and 4.8V at room temperature and near to 90% after 30 cycles at elevated temperature of 55℃ at 1C charge-discharge rate. SEM studies shows that the surface morphology of TiO{sub}2-modified LiMn{sub}2O{sub}4 was different from that of pristine LiMn{sub}2O{sub}4. Powder X-ray diffraction indicated that spinel was the only detected phase in TiO{sub}2-modified LiMn{sub}2O{sub}4. Introduction of Ti into LiMn{sub}2O{sub}4 changed the electronic structures of the particle surface. Therefore a surface solid compound of LiTi{sub}xMn{sub}(2-x)O{sub}4 may be formed on LiMn{sub}2O{sub}4. The improved electrochemical performance of surface-modified LiMn{sub}2O{sub}4 was attributed to the improved stability of crystalline structure and the higher Li{sup}+ conductivity.