Regulating Surface Oxygen Activity by Perovskite‐Coating‐Stabilized Ultrahigh‐Nickel Layered Oxide Cathodes

Abstract Ultrahigh‐Ni layered oxides are proposed as promising cathodes to fulfill the range demand of electric vehicles; yet, they are still haunted by compromised cyclability and thermal robustness. State‐of‐the‐art surface coating has been applied to solve the instability via blocking the physical contact between the electrolyte and the highly active Ni⁴⁺ ions on the cathode surface, but it falls short in handling the chemo–physical mobility of the oxidized lattice oxygen ions in the cathode. Herein, a direct regulation strategy is proposed to accommodate the highly active anionic redox within the solid phase. By leveraging the stable oxygen vacancies/interstitials in a lithium and oxygen dual‐ion conductor (layered perovskite La₄NiLiO₈) coating layer, the reactivity of the surface lattice oxygen ion is dramatically restrained. As a result, the oxygen release from the lattice is suppressed, as well as the undesired irreversible phase transition and intergranular mechanical cracking. Meanwhile, the introduced dual‐ion conductor can also facilitate lithium‐ion diffusion kinetics and electronic conductivity on the particle surface. This work demonstrates that accommodating the anionic redox chemistry by dual‐ion conductors is an effective strategy for capacity versus stability juggling of the high‐energy cathodes.