Al2O3 coated single-crystalline hexagonal nanosheets of LiNi0.6Co0.2Mn0.2O2 cathode materials for the high-performance lithium-ion batteries

摘要

The LiNi0.6Co0.2Mn0.2O2 (NCM) cathode material is highly potential for the wide application in lithium-ion batteries due to its moderate cost and high specific capacity. However, the problems of its poor cycling stability and rate performance need to be further solved. Designing a single-crystal nanostructure of the NCM materials is an effective strategy to increase the rate characteristics, however, the performance decay and safety issues are still there due to the irreversible side reactions and structure degradation. In this study, the single crystalline hexagonal nanosheets of NCM material have been prepared using a hydrothermal process, and various amounts of Al2O3 are further controllably coated on the surface of NCM. The results show that a suitable amount of Al2O3 coating is conducive to the formation of a better layered structure NCM with smaller cation disorder and leads to higher discharge capacity, rate performance and longer cyclic life than the pristine material, due to the stabilized layered structure of cathode materials, the alleviated electrode/electrolyte side reactions and the favored diffusion of lithium ions.