Oxygen-Vacancy-Reinforced Vanadium Oxide/Graphene Heterojunction for Accelerated Zinc Storage with Long Life Span

Abstract

Vanadium trioxide (V6O13) cathode has recently aroused intensive interest for aqueous zinc-ion batteries (AZIBs) due to their structural and electrochemical diversities. However, it undergoes sluggish reaction kinetics and significant capacity decay during prolonged cycling. Herein, an oxygen-vacancy-reinforced heterojunction in V6O13−x/reduced graphene oxide (rGO) cathode is designed through electrostatic assembly and annealing strategy. The abundant oxygen vacancies existing in V6O13−x weaken the electrostatic attraction with the inserted Zn2+; the external electric field constructed by the heterointerfaces between V6O13−x and rGO provides additional built-in driving force for Zn2+ migration; the oxygen-vacancy-enriched V6O13−x highly dispersed on rGO fabricates the interconnected conductive network, which achieves rapid Zn2+ migration from heterointerfaces to lattice. Consequently, the obtained 2D heterostructure exhibits a remarkable capacity of 424.5 mAh g−1 at 0.1 A g−1, and a stable capacity retention (96% after 5800 cycles) at the fast discharge rate of 10 A g−1. Besides, a flexible pouch-type AZIB with real-life practicability is fabricated, which can successfully power commercial products, and maintain stable zinc-ion storage performances even under bending, heavy strikes, and pressure condition. A series of quantitative investigation of pouch batteries demonstrates the possibility of pushing pouch-type AZIBs to realistic energy storage market.