Effect of annealing temperature on the microstructure and electrochemical performance of Li2ZrO3-modified Ni-rich NCM811

Abstract

Li2ZrO3 (LZO) coating has been routinely applied on Ni-rich NCM cathode materials via two-step processes to improve their electrochemical performances, but procedures for sample preparation remain elusive. Ni-rich NCM materials are particularly sensitive to temperatures, but annealing temperatures show random variation between 400 and 850 °C in literatures. In this work, the influence of annealing temperature on microstructures and electrochemical properties are systematically studied for the LZO-modified NCM811. It is found that, a thicker LZO coating with amorphous features can be obtained at a lower annealing temperature; but the LZO is fully dissolved into the crystal lattice of NCM811 at a higher temperature. The best electrochemical performance is achieved at the condition of 750 °C, because an optimized annealing temperature can introduce moderate Zr4+ doping and obtain high-quality coating layers. This work offers a guidance for industrial to enhance electrochemical performances of Ni-rich NCM cathode materials during surface modification processes.