Synergistic Surface Reinforcement and Jahn‐Teller Distortion Migration by MgAl ₂ O ₄ Coating for Long‐Term Cycling Lithium‐Rich Layered Oxides

Abstract Anionic redox and structural distortion in lithium‐rich layered oxide cathode materials under high‐voltage operation trigger serve surface degradation and subsequent persistent transition metal dissolution, leading to continuous performance deterioration. To enhance surface structural stability, this work constructs an MgAl 2 O 4 spinel modified interfacial passivation layer with high lattice compatibility with the bulk material, which significantly facilitates lithium‐ion diffusion and improve rate performance. Benefiting from gradient oxygen infusion and reinforced surface metal‐oxygen bonds, the modified sample shows reduced oxygen evolution and a more stable cathode‐electrolyte interface. Crucially, the in situ XRD patterns and XAFS results demonstrate the strategy effectively alleviates [MnO 6 ] octahedra distortion and migrate Jahn‐Teller Effect during discharge process, most likely owing to the migration of Mg 2+ ions from the surface into the bulk lattice. Consequently, the modified material achieves a remarkable capacity retention of 99.2% after 500 cycles at 1.0 C, a substantial improvement over the unmodified sample (57.9%). This straightforward modification strategy provides a practical pathway toward stabilizing lithium‐rich cathode materials for future application.