Synergistic carbon and oxygen vacancy engineering on vanadium dioxide nanobelts for efficient aqueous zinc-ion batteries

Abstract

Vanadium-based compounds with stable crystal structures and high capacities are promising cathode materials in aqueous zinc-ion batteries (AZIBs); nevertheless, the sluggish solid-phase diffusion kinetics of zinc ions and poor electronic conductivity have obstructed their application. Herein, this study proposes a synergistic engineering approach involving carbon and oxygen vacancies to improve the performance of VO₂. Compared to VO₂, VO₂@C shows improved electron/ion transport kinetics due to carbon coating, oxygen vacancy, expanded lattice, and reduced grain size. This composite also offers improved structural stability and extra active sites, enhancing zinc-ion storage performance. The optimized VO₂@C-350 composite electrode displays a remarkable discharge capacity of 391 mA h g⁻¹ at 0.1 A g⁻¹ over 100 cycles and maintains good cycle stability performance at 2 A g⁻¹ for over 2000 cycles. Further analysis has identified that its reaction mechanism involves a co-intercalation/de-intercalation process of the proton (H⁺) and Zn²⁺. This innovative synergistic engineering approach can be implemented in other zinc storage materials to achieve efficient AZIBs.