High-nickel ternary LiNi0.85Co0.11Mn0.04O2 ( NCM85 ) is a promising cathode material for high-perform-ance lithium-ion batteries. However, Li loss and cationic mixing are very likely to occur during calcination at high temperature, resulting in the formation of a disordered rock salt phase on the surface of the positive electrode parti-cles. A method of preparation of in situ-modified NCM85 by treatment with H3PO4 is proposed. A uniform Li3PO4 coating layer is formed on the surface of NCM85 , which effectively improves the electrochemical performance of NCM85 and stabilizes the cathode-electrolyte interface. Compared with the pristine NCM85 electrode, the cathode electrode ( Li3PO4@NCM85 ) with the appropriate amount of Li3PO4 coating exhibited excellent electrochemical performance. The specific discharge capacity was 169. 2 mA·h/g after 200 cycles at 0. 5 C (200 mA/g) in the voltage range 2. 75-4. 3 V. The capacity retention rate is as high as 84％, because the residual lithium on the sur-face of the material is consumed during the formation of the Li3PO4 coating layer, which reduces the mixing of Li+/Ni2+ and enhances the stability of the structure. In addition, the Li3PO4 coating can increase the ionic conductivi-ty, accelerate the Li+ diffusion rate, and inhibit phase transformation, cation mixing and volume shrinkage. Our study of the influence of surface modification on the interface mechanism of materials should promote the develop-ment of cathode electrode materials for the next generation of high-energy lithium-ion batteries.
维普
万方数据