Electrolyte‐Induced Interfacial ZnMn ₂ O ₄ Formation on MnO ₂ @MOF‐5 Cathodes for Ultra‐Stable Aqueous Zinc‐Ion Batteries

ABSTRACT In aqueous zinc‐ion batteries (AZIBs), enhancing electrochemical stability through interfacial engineering has gained significant attention. This study introduces an interfacial phase reconstruction strategy by leveraging the confined induction capability of MOF‐5. Mn ^{2 +} ions preloaded in the electrolyte (2 M ZnSO ₄ and 0.2 M MnSO ₄ ) preferentially engage with Zn ^{2 +} at the MOF‐5 surface, forming a dynamic and reversible in situ ZnMn ₂ O ₄ interphase that enhances the performance and stability of AZIBs. ZnMn ₂ O ₄ functions as a self‐expanding, reversible interfacial host that is vital for managing energy storage and ensuring structural stability. The presence of MOF‐5 provides confined nucleation sites that enable the selective deposition of ZnMn ₂ O ₄ , thereby protecting the underlying MnO ₂ from collapse and dissolution. With this dynamic interfacial engineering, the CC/MO@MOF‐5 electrode demonstrates a reversible capacity of 173.7 mAh g ^{− 1} at 0.1 A g ^{− 1} and gradually activates to 79 mAh g ^{− 1} after 5000 cycles at 1 A g ^{− 1} . The electrochemical reversibility of ZnMn ₂ O ₄ and its voltage‐dependent phase evolution are systematically investigated. This work redefines ZnMn ₂ O ₄ as a tunable and electrochemically active main storage phase and establishes an electrolyte–interphase co‐design strategy for aqueous multivalent ion batteries under extreme conditions.