Enhanced high-potential and elevated-temperature cycling stability of LiMn2O4 cathode by TiO2 modification for Li-ion battery

The surface of spinel LiMn2O4 was modified with TiO2 by a simple sol–gel method to improve its electrochemical performance at elevated temperatures and higher working potentials. Compared with pristine LiMn2O4, surface-modification improved the cycling stability of the material. The capacity retention of TiO2-modified LiMn2O4 was more than 85% after 60 cycles at high potential cycles between 3.0 and 4.8 V at room temperature and near to 90% after 30 cycles at elevated temperature of 55 °C at 1C charge–discharge rate. SEM studies shows that the surface morphology of TiO2-modified LiMn2O4 was different from that of pristine LiMn2O4. Powder X-ray diffraction indicated that spinel was the only detected phase in TiO2-modified LiMn2O4. Introduction of Ti into LiMn2O4 changed the electronic structures of the particle surface. Therefore a surface solid compound of LiTixMn2−xO4 may be formed on LiMn2O4. The improved electrochemical performance of surface-modified LiMn2O4 was attributed to the improved stability of crystalline structure and the higher Li+ conductivity.