Hierarchical-Porous V-MOF Cathodes Enabling High-Performance Aqueous Zinc-Ion Hybrid Batteries
Aqueous zinc-ion batteries (ZIBs) are constrained by cathode materials that exhibit sluggish Zn2+ diffusion kinetics, structural degradation under hydrated Zn2+ insertion, and insufficient redox accessibility. This study reports a hierarchically porous vanadium-based metal-organic framework (h-V-MOF) cathode that integrates high specific surface area (1162.5 m2 g−1), reversible structural evolution, and mixed battery-supercapacitor charge storage. The h-V-MOF delivers a specific capacity of 304.1 mAh g−1 and retains 92.3% of initial capacity after 2000 cycles at 5.0 A g−1. Mechanistic analysis reveals that hierarchical porosity facilitates electric double-layer adsorption while vanadium redox centers enable stable Zn2+ insertion/extraction. The hybrid storage mechanism, combining surface-controlled capacitive contributions with diffusion-limited faradaic reactions, yields enhanced charge storage density relative to conventional oxide cathodes. These findings establish a design paradigm for MOF-based multifunctional electrodes in next-generation hybrid energy devices.