Design and mechanism exploration of single-crystalline NCM811 materials with superior comprehensive performance for Li-ion batteries

Abstract

Although single-crystalline LiNixCoyMn1-x-yO2 (SC NCM) materials have been confirmed to have advantages in cycle performance, storage performance and thermal stability, the comprehensive performance of SC NCM materials is not perfect enough nowadays. And the current research on the modification mostly focuses on polycrystalline NCM materials, the modification of SC NCM materials is rare. Therefore, the synthesis and modification of SC NCM materials deserve special attention. In this work, the SC high-nickel LiNi0.8Co0.1Mn0.1O2 (NCM811) is modified by doping with titanium (Ti) element. The doped material can maintain better structural stability, and suppress the side reaction between the material interface and the electrolyte, so the cycling performance is significantly improved. Doping enlarges the transport channel of Li+ in the material, thereby increasing the rate property. The lattice slip phenomenon of the modified material under high voltage is significantly suppressed, and the oxygen release and the reactivity with the electrolyte at high temperature of the material after delithiation are reduced, so the high voltage resistance and thermal stability are significantly enhanced. In conclusion, the comprehensive properties of SC NCM811 materials are improved by doping, and detailed mechanism study is carried out, which can provide reference for the further modification of SC NCM materials.