Abstract:The cycling characteristics and low specific capacity of LiMn₂O₄have always been the greatest obstacle to its commercialization. For the improvement of cycle performance, the surface of LiCo_0.05Mn_1.95O₄ was coated with very fine SiO₂-TiO₂composite prepared by sol-gel method. The structure and morphology of the coating materials were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrochemical performances of uncoated and SiO₂-TiO₂coated LiCo_0.05Mn_1.95O₄  spinel at 25℃and 55℃were studied with a voltage range of 3.0 4.35V and a current density of 0.1 mA/cm². There is a slight decrease in the initial discharge capacity of coated LiCo_0.05Mn_1.95O₄ (119mA·h/g) compared with that of uncoated (123 mA·h/g). However the cycle ability of LiCo_0.05Mn_1.95O₄coated by SiO₂-TiO₂is improved. It is proposed that surface treatment is an effective method to improve the cycle performance of LiCo_0.05Mn_1.95O₄. The surface modification is successful in minimizing the harmful side reactions within the batteries by placing a protective barrier layer between the oxidizing cathode material and the liquid electrolyte.

Key words: lithium-ion batteries; surface modification; SiO₂-TiO₂coating; LiCo_0.05Mn_1.95O₄ cathode