Recent advances in Ni-rich layered oxide particle materials for lithium-ion batteries

Ni-rich layered oxides with chemical formula of LiNixCoyMnzO2 or LiNixCoyAlzO2 (x+y+z=1, x >= 0.6) have been considered as promising cathode materials for lithium-ion batteries (LIBs) because of their high specific capacity (>= 180 mAh g(-)(1)) and acceptable manufacture cost. However, the problems associated with high Ni content severely restrict their large-scale applications. In this review, we summarize the recent advances in Ni-rich layered oxide particle materials for LIBs. We begin with the introduction of the structure, redox mechanism, and problems of Ni-rich layered oxides, mainly including residual lithium compounds, gas evolution, rock-salt phase formation, microcrack of particles, dissolution of transitionmetal ions, and thermal runaway. Then, four strategies (primary particle engineering, surface coating, doping, concentration gradient design) toward solving the problems of Ni-rich layered oxides will be systematically discussed with the emphasis on structure-performance relationships. To achieve satisfied comprehensive performance and accelerate large-scale applications of Ni-rich layered oxides, the combination of two or more strategies (particle engineering and surface/bulk stabilization techniques) with synergistic effects is necessary in future works. This review would promote further research and application of high-performance Ni-rich layered oxide particle materials for LIBs. (C) 2020 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.