Enhanced electrochemical performance of cobalt oxide layers coated LiNiCoMnO by polyvinylpyrrolidone-assisted method cathode for Li-ion batteries.

LiNiCoMnO (NCM811) stands out among many cathode materials for lithium-ion batteries due to its high energy density. However, the Li-Ni mixing phenomenon and the side reactions between the active cathode material and the electrolyte during the charging and discharging process have hindered its commercial application. CoO is a transition metal oxide with a spinel structure that can provide Li embedding sites for NCM811 and is considered a competitive coating material. Here, we use polyvinylpyrrolidone (PVP) as the assisting material and Co(NO)·6HO as the cobalt source to form a uniform and continuous CoO coating on the surface the of NCM811 by a simple wet chemical method. The formed coating can avoid direct contact between NCM811 and the electrolyte, enhance the structural stability of the material surface, and reduce the polarization of the electrode during cycling. The experimental results demonstrate that the performance of the modified cathode materials is higher than that of NCM811, with a higher initial specific capacity (183.59 mAh·g at 0.1C), specific capacity (151.10 mAh·g at 2C) and cycle performance. The performances are better than those of many oxide coating materials at this research stage and provide a potential solution for the practical application of NCM811 lithium-ion batteries that provide high energy.