Dynamic Interfacial S–O Bonding Stabilizes Oxygen Redox Through Reversible Electron Confinement

The reversible activation of lattice oxygen represents a transformative opportunity for high‐energy battery electrodes but remains fundamentally limited by the instability of oxidized oxygen states. In layered oxide cathodes, oxygen oxidation generates oxygen‐centered hole states that become electronically unstable at particle surfaces, triggering oxygen loss, interfacial reconstruction, and irreversible electrochemical degradation. Here, we develop an interfacial electronic regulation strategy that stabilizes oxygen redox through reversible sulfur–oxygen (S–O) bonding. During charging, dynamic S–O bond formation at the cathode surface confines oxygen hole states and suppresses their delocalization and irreversible evolutions, whereas bond dissociation upon discharge restores the lattice oxygen electronic configuration and enables reversible oxygen redox. Applied to the Na 0.72 Li 0.24 Mn 0.76 O 2 layered oxide cathode, this strategy enables stable oxygen redox activity, mitigates voltage decay, and improves long‐term cycling stability. These findings establish reversible interfacial electron confinement as a general design principle for regulating unstable oxygen electronic states and advancing durable high‐energy‐storage materials.