Orbital Stabilization of Anionic Redox via Surface Restructuration for Li‐Rich Mn‐Based Layered Oxides

Abstract

ABSTRACT Lithium‐rich layered oxides are renowned for their high capacity, originating from both cationic and anionic redox reactions. However, the anionic redox process often induces the formation of O–O dimers, triggering oxygen release and transition metal migration that typically initiate at the particle surface and lead to progressive structural degradation and performance decay. In this study, we report a lithium‐rich manganese‐based layered oxide cathode featuring a surface reconstruction layer in which nickel ions occupy the 4 h Wyckoff sites within the Li 2 MnO 3 phase. This surface‐site‐specific nickel occupation induces parallel alignment of electron‐depleted O 2p orbitals, effectively suppressing the formation of unstable O–O dimers and inhibiting oxygen release. The engineered cathode delivers a remarkable reversible capacity of 325 mAh g − 1 at 0.1C (20 mA g − 1 ), along with an outstanding rate capability of 272.8 mAh g − 1 at 1C (200 mA g − 1 ) and 90% capacity retention after 300 cycles. This surface engineering strategy establishes a novel structural response mechanism for oxygen redox reactions, enabling the simultaneous achievement of high capacity and long‐term cycling stability. The findings provide critical insights for the development of advanced high‐energy‐density cathode materials.