Simultaneous Interlayer Expansion and Defect Engineering in Hydrated V2O5 Cathodes for Fast-Charging Aqueous Zinc Batteries
Abstract
Aqueous zinc-ion batteries (AZIBs) offer a safe, scalable path to grid storage, but their progress is limited by cathode materials that exhibit sluggish Zn2+ diffusion. Commercial vanadium pentoxide (V2O5), though possessing a high theoretical capacity, inherently suffers from this kinetic limitation. Here, a water-assisted mechanochemical strategy is developed to introduce interlayer hydration and V4+-rich oxygen defects into commercial V2O5, improving both ion transport and electron transfer. Hydration expands the interlayer spacing for Zn2+ migration, while V4+ states enhance charge transfer, forming a coupled ion–electron pathway. The treatment also expands the (001) spacing, creates oxygen vacancies, and exfoliates bulk particles into porous nanosheets. The optimally modified V2O5 cathode delivers exceptional Zn2+ storage performance with a high reversible capacity of 563.7 mAh g–1 at 0.2 A g–1, outstanding cycling stability with 237 mAh g–1 retained after 5000 cycles at 10 A g–1, and a near-unity Coulombic efficiency. Comprehensive kinetic analyses confirm that the modified V2O5 exhibits a dominant pseudocapacitive mechanism, significantly reduced charge-transfer resistance, and an order-of-magnitude enhancement in the apparent Zn2+ diffusion coefficient. This work demonstrates that the coordinated regulation of interlayer water and oxygen vacancies is a highly effective strategy to activate commercial V2O5, and the mechanochemical route provides a potentially scalable strategy for activating commercial oxide cathode materials.