Crystal Plane Engineering in Ni-Rich Layered Cathodes LiNixCoyMn1–x–yO2(NCM, x ≥ 0.6): A Comprehensive Review

High-nickel layered LiNixCoyMn1–x–yO2 (NCM, x ≥ 0.6) cathodes are promising for high-energy lithium-ion batteries but face challenges in structural stability and interfacial dynamics. Key limitations include irreversible phase transitions induced by oxygen loss, concentration polarization resulting from lithium-ion diffusion anisotropy, and surface instability arising from highly reactive facets such as {104}. Crystal facet engineering addresses these issues by balancing facet-dependent properties: high-index facets ({104}, {010}) enhance Li+ transport but exacerbate oxygen release, whereas low-index {003} facets stabilize the oxygen sublattice at the expense of reaction kinetics. Current technologies nevertheless face challenges including inadequate compatibility between facet orientation and electrolyte and unclear synergistic mechanisms among multiple crystal planes, necessitating precise synthetic strategies for customized facet-performance design. This review elucidates structure–performance relationships governed by crystal orientation, systematically investigating precursor crystallization control and lithiation optimization for directional exposure of active facets ({010} and {104}). The underlying mechanisms connecting reduced lithium-ion diffusion barriers to suppressed structural degradation are revealed. Single-crystal particle alignment strategies significantly improve cycling stability by eliminating grain boundary defects, while novel synthesis approaches, including coprecipitation with chelating agents, organic/inorganic doping, preoxidation, and molten-salt-assisted sintering, provide new pathways for facet-selective growth. These findings establish theoretical foundations for high-energy-density cathode design, highlighting the pivotal role of crystallographic regulation in advancing next-generation battery technologies.