Asymmetric‐Orbital‐Hybridization Induced Electron Redistribution Enabling Stable Sodium Layered Oxides

Abstract Layered transition metal (TM) oxides have garnered great attention as viable cathodes for sodium‐ion batteries (SIBs), but the challenges of complicated multiphase transitions, severe structural deterioration and unstable oxygen redox reaction still hamper their practical application. Herein, a universal electron redistribution strategy based on the orbital hybridization regulation is proposed and NaNi _0.5 Mn _0.35 Ti _0.15 O ₂ (NNMTO) is introduced as a model cathode considering the distinct electronegativity between Ni and Ti. The nonequivalent electron distribution induced by the covalency competition within asymmetric Ni _3d ‐O _2p ‐Ti _3d backbone (Ni─O─Ti charge transfer via the bridging oxygen atom) delocalizes the electrons between Ni and O and modulates the local chemical environment around O. The enhanced orbital coupling combined with increased Ni─O covalency can not only suppress the over‐oxidation of lattice oxygen and improve the reversibility of oxygen redox, but also alleviate the cooperative Jahn–Teller distortion of Ni ³⁺ O ₆ octahedron and prevent the phase transition from O3′ to the detrimental O3″ phase by constructing a more rigid TM─O framework. As a result, NNMTO shows a sustained reversible capacity and remarkable cycling stability that is rooted in reversible oxygen and TM redox processes. This study provides an alternative avenue to construct high‐performance SIBs from the perspective of local chemistry and orbital hybridization modulation.