Phase-Transformable MOF-Derived α-ZnMoO4 Cathode Featuring Oxygen Vacancies and Lattice Lubrication for Enhanced Zinc-Ion Storage

A triclinic zinc molybdate (α-ZnMoO₄) cathode was developed via the pyrolysis of Zn–Mo bimetallic metal–organic frameworks (MOFs) as sacrificial intermediates for high-performance aqueous zinc-ion batteries (AZIBs). After high-temperature pyrolysis, the MOF-derived single-phase α-ZnMoO₄ consists of particles approximately 4 μm in size. Notably, the structure of MOFderived α-ZnMoO₄ transitions into a preferred α-ZnMoO₄·0.8H₂O phase with expanded lattice spacing during the initial discharge process, facilitating efficient Zn²⁺ intercalation/deintercalation. This hydrated structure remains stable throughout cycling, contributing to its excellent electrochemical performance. The cathode delivers a high reversible capacity of 380 mAh g⁻¹ at 0.05 A g⁻¹ and retains 95% of its capacity after 500 cycles at 0.2 A g⁻¹. Electrochemical and structural analyses reveal that the synergistic effects of phase transformation, oxygen vacancies, and water-mediated lattice lubrication contribute to the superior cycling stability and Zn²⁺ storage kinetics of the material. These findings highlight the potential of MOF-derived oxide cathodes and provide a strategic pathway for designing advanced materials for next-generation AZIBs.