Interface Reaction‐Controlled Electrochemically Active Coatings for Ni‐Rich Cathodes in Lithium‐Ion Batteries

Ni‐rich cathode materials are widely used in commercial lithium‐ion batteries (LIBs) because of their high reversible capacities and operating voltages. However, their practical applications are limited by intrinsic structural degradation and interfacial instability. High Ni content accelerates interfacial side reactions at the cathode–electrolyte interface and promotes irreversible phase transitions, leading to transition metal dissolution, microcrack formation, and gradual capacity fading during cycling. To address these limitations, we propose a surface‐engineering strategy that employs a disordered rock‐salt Li 1.13 Fe 0.31 Ni 0.15 Ti 0.41 O 2 (LFNTO) functional coating to enhance the structural stability of Ni‐rich cathode materials. The electrochemically active LFNTO not only provides additional capacity but also stabilizes the cathode–electrolyte interface, effectively suppressing side reactions and alleviating irreversible phase transitions. Moreover, the LFNTO functional coating layer compensates for the capacity loss typically associated with conventional surface‐coating approaches and extends the cycling stability without sacrificing energy density. These findings highlight that the aqueous‐processable LFNTO surface coating offers a cost‐effective, scalable pathway to enhance both interfacial reversibility and long‐term durability of Ni‐rich cathode materials, thereby providing valuable insights for the development of advanced cathode materials for high‐energy LIBs.