Mitigating irreversible phase transition of Y-doped LiNi0.925Co0.03Mn0.045O2 by lattice engineering

Abstract

The commercialization of ternary layered cathode materials with a relative nickel content of more than 90 % faces serious challenges. Among them, it is urgent to address the issues of rapid capacity degradation and structural degradation. Herein, we provide a simple process for doping yttrium at the precursor preparation stage. The feasibility of yttrium doping in the precursor and the positive effects of yttrium ions on the crystal structure and properties of the cathode materials are scientifically explained by a variety of characterization and testing methods, such as Eh-pH, Particle Size Analyzer, ICP, SEM, EDS, XRD, XPS, HRTEM, dQ/dV, CV, EIS and DFT. Yttrium-doped NCMY cathode materials have more stable lattice oxygen and significantly less irreversible phase transition. Furthermore, the electrochemical performance of the NCMY cathode material is significantly improved, with a capacity retention rate of 82.71 % after 150 cycles at a current density of 1C, which is much higher than 65.39 % for NCM. The NCMY cathode material significantly improves the lithium ion diffusion ability, especially at the high rate of 10C, the discharge specific capacity is still as high as 177.05 mAh g−1.