Manipulating Oxygen Vacancies to Spur Ion Kinetics in V₂O₅ Structures for Superior Aqueous Zinc-Ion Batteries

Vanadium-based intercalation materials have attracted considerable attention for aqueous zinc-ion batteries (ZIBs). However, the sluggish interlaminar diffusion of zinc ions due to the strong electrostatic interaction, severely restricts their practical application. Herein, oxygen vacancy-enriched V₂O₅ structures (Zn_0.125V₂O₅·0.95H₂O nanoflowers, O_v-ZVO) with expanded interlamellar space and excellent structural stability are prepared for superior ZIBs. In situ electron paramagnetic resonance (EPR) and X-ray diffraction (XRD) characterization revealed that numerous oxygen vacancies are generated at a relatively low reaction temperature because of partially escaped lattice water. In situ spectroscopy and density functional theory (DFT) calculations unraveled that the existence of oxygen vacancies lowered Zn²⁺ diffusion barriers in O_v-ZVO and weakened the interaction between Zn and O atoms, thus contributing to excellent electrochemical performance. The Zn||O_v-ZVO battery displayed a remarkable capacity of 402 mAh g⁻¹ at 0.1 A g⁻¹ and impressive energy output of 193 Wh kg⁻¹ at 2673 W kg⁻¹. As a proof of concept, the Zn||O_v-ZVO pouch cell can reach a high capacity of 350 mAh g⁻¹ at 0.5 A g⁻¹, demonstrating its enormous potential for practical application. This study provides fundamental insights into formation of oxygen-vacant nanostructures and generated oxygen vacancies improving electrochemical performance, directing new pathways toward defect-functionalized advanced materials.