Research On The Synthesis, Modification And Electrochemical Performance Of Active Materials For Lithium Ion Batteries

Li-ion batteries, which have high energy density and stable performance, have been widely used in portable electronics, electric vehicles, and stationary energy storage system. The quality of lithium ion battery is highly dependent on the electrode performance of active materials; thus, the research on the active materials for lithium ion batteries is urgent and of great importance. In this thesis, research have been focused on TiO₂,Li₄Ti₅O₁₂ and LiNi_0.5Mn_1.5O₄, demonstrating the relationship between the structure of materials and corresponding electrode performance as applied to lithium ion batteries. Besides, technique of surface-modification has been applied to enhance the electrode performance in our studies. In addition, LiTiOPO₄ has been applied to lithium ion batteries for the first time with good performance, whose reaction mechanism was explored and illustrated. Particularly, the content of thesis includes:（1） porous TiO₂ coated with nitrogen-doped carbon was successfully fabricated with ethylene diamine as carbon source, which exhibits an excellent rate capability and good cyclability;（2） explore the mechanism of the electrochemical activity of LiTiOPO₄ with lithium when the lower cut-off potential was set to 0.1 V;（3） porous LiNi_0.5Mn_1.5O₄ microsphere was fabricated by spray drying method with modified conditions. A good electrode performance was displayed when it was applied to lithium ion batteries due to its porous structure and dominant（111） plane.（4） using hydrogen-containing silicone oil to modify the surface of Li₄Ti₅O₁₂ to enhance its hydrophobicity, which is beneficial somehow in practical application for lithium ion batteries.