Oxygen Stacking Controlled Cyclic Capacity and Stability of Layered Oxide Cathodes

Abstract The development of high‐performance layered oxide cathodes for sodium‐ion batteries remains a significant challenge, hampered by inherent limitations in capacity utilization and irreversible structural degradation during sodium (de)intercalation. Herein, an oxygen stacking regulation strategy is presented that precisely manipulates both oxygen stacking sequence (o‐SS) and the spatial distribution of active oxygen ions, to engineer advanced layered oxides. It is demonstrated that the ordered double‐layer (O‐DL) oxides exhibit superior cycling stability, while the partially disordered triple‐layer (PD‐TL) oxides deliver higher specific capacity. Combined in situ characterization techniques and theoretical calculations elucidate the underlying mechanisms: the enhanced stability of O‐DL oxides originates from the structural robustness of the double‐layer o‐SS, whereas the high capacity of PD‐TL oxides arises from stacking‐faults inducing a partially disordered structure, effectively localizing the spatial distribution of active oxygen ions. Strikingly, by integrating both the structural features, the partially disordered double‐layer oxides are further developed. This dual strategy unlocks exceptional electrochemical performance, achieving a high specific capacity (219 mAh g −1 ) alongside remarkable cycling stability (86.5% capacity retention after 50 cycles). This work establishes a fundamental mechanistic understanding of how oxygen stacking regulation governs cathode performance, providing a novel paradigm for the rational design of high‐performance layered oxides.