Tailoring Lithium‐Rich NMC Cathode Materials for High‐Energy Lithium‐Ion Batteries

Lithium‐ion batteries (LIBs) are central to modern energy storage, but further improvements in energy density are limited by the intrinsic capacity of conventional cathodes such as LiCoO 2 and LiNi x Mn y Co z O 2 (NMC), which rely primarily on transition‐metal cationic redox reactions. Lithium‐rich NMC (Li 1+ x M 1− x O 2 ; M = Ni, Mn, Co) cathodes have emerged as promising alternatives because their coupled cationic‐anionic redox processes enable reversible capacities exceeding 250 mA h g −1 while reducing cobalt content. However, their practical application is hindered by low initial Coulombic efficiency, sluggish reaction kinetics, voltage fading, and capacity degradation. This review critically examines the crystal structure, redox mechanisms, degradation pathways, and performance enhancement strategies of lithium‐rich NMC cathodes. It discusses the origins of cationic and anionic redox activity, the structural and chemical evolution responsible for performance decay, and recent advances in synthesis, compositional tuning, elemental doping, and surface engineering. Particular attention is given to cobalt‐lean and cobalt‐free compositions, full‐cell and pouch‐cell performance, coupled degradation mechanisms, and industrial challenges. By linking fundamental reaction mechanisms with material design strategies, this review provides insights into structure–property relationships and practical pathways for developing high‐energy, durable LIBs.