Taming “Voltage Valley” in Conversion‐Type Cu 2 O Cathode Via Epitaxial MOF Integration for High‐Performance Zinc‐Ion Batteries

Abstract Conversion‐type cathodes represent a promising route to high‐energy‐density aqueous zinc‐ion batteries (AZIBs), yet their practical deployment remains challenged by irreversible phase transitions and pronounced reaction heterogeneity. In this study, the initial discharge “voltage valley” phenomenon is identified as a key indicator of kinetic instability and structural degradation in the conversion reaction of typical Cu 2 O cathode. To this end, an in situ epitaxial growth strategy is developed to construct conductive Cu‐based metal‐organic frameworks (Cu‐MOFs) armor on Cu 2 O cubes, seamlessly integrating to form robust core–shell structures. The multifunctional MOFs layer serves as an ion‐flux homogenizer, electron transport network, and nanoscale reaction cage, which collectively suppress the voltage valley, regulate reaction kinetics, and enhance conversion reversibility. The optimized Cu 2 O@Cu‐MOF cathode delivers a high capacity of 235 mAh g −1 even at 5 A g −1 and achieves outstanding cycling stability with 82.2% capacity retention after more than 9000 cycles. This work not only provides a universal epitaxial stabilization strategy for conversion‐type electrodes but also deciphers the critical role of interfacial ion/electron regulation in achieving sustainable conversion reactions.