Excellent structural stability and electrochemical properties of LiNi0.9Co0.05Mn0.05O2 material by surface Ni2+ anchoring and Cs+ doping

The ultra-high nickel cathode material has important application prospect in power lithium-ion batteries. However, the poor structural stability and serious surface/interfacial side reactions during long cycles severely hinder the material's practical application. In this paper, Cs+ doping and polymethyl methacrylate (PMMA) coating are used to synergistically modify the NCM955 material. The results show that the corresponding discharge specific capacity of NCMCs-2@P-2 material reaches 152.02 mAh/g at 1 C (1 C = 200 mA/g) and 125.66 mAh/g at 5 C after 300 cycles, and the capacity retention is 78.11% and 72.21%, respectively. In addition, it still maintains 156.36 mAh/g discharge specific capacity at 10 C, and these rate and cycle properties exceed those reported on ultra-high nickel cathode material. Moreover, NCMCs-2@P-2 material has higher migration energy barrier of Ni2+ and lower migration energy barrier of Li+ than that of NCM955 material. Therefore, NCMCs-2@P-2 material has excellent electrochemical properties, which has been proved by a series of structural characterization, theoretical calculation and performance test. The synergistic enhancement of Cs+ doping and PMMA coating accelerates lithium ion diffusion kinetics, stabilizes crystal structure, and inhabits surface/interface side reaction.