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

Abstract

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 (Zn0.125V2O5·0.95H2O nanoflowers, Ov-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 Ov-ZVO and weakened the interaction between Zn and O atoms, thus contributing to excellent electrochemical performance. The Zn||Ov-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||Ov-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.