Advancements in Addressing Microcrack Formation in Ni–Rich Layered Oxide Cathodes for Lithium–Ion Batteries

Nickel–rich layered oxides of LiNi$_{1–x–y}$CoxMn(Al)yO2 (where 1–x–y > 0.6) are considered promising cathode active materials for lithium-ion batteries (LIBs) due to their high reversible capacity and energy density. However, the widespread application of NCM(A) is limited by microstructural degradation caused by the anisotropic shrinkage and expansion of primary particles during the H2!H3 phase transition. In this mini–review, we comprehensively discuss the formation of microcracks, subsequent material degradation, and related alleviation strategies in nickel–rich layered NCM(A). Firstly, theories on microcracks’ formation and evolution mechanisms are presented and critically analyzed. Secondly, recent advancements in mitigation strategies to prevent degradation in Ni–rich NCM/NCA are highlighted. These strategies include doping, surface coating, structural optimization, and morphology engineering. Finally, we provide an outlook and perspective to identify promising
strategies that may enable the practical application of Ni–rich NCM/NCA in commercial settings.