Electrolyte-Induced Interfacial ZnMn2O4 Formation on MnO2@MOF-5 Cathodes for Ultra-Stable Aqueous Zinc-Ion Batteries.

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. Mn2 + ions preloaded in the electrolyte (2 M ZnSO4 and 0.2 M MnSO4) preferentially engage with Zn2 + at the MOF-5 surface, forming a dynamic and reversible in situ ZnMn2O4 interphase that enhances the performance and stability of AZIBs. ZnMn2O4 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 ZnMn2O4, thereby protecting the underlying MnO2 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 ZnMn2O4 and its voltage-dependent phase evolution are systematically investigated. This work redefines ZnMn2O4 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.