Oxygen vacancies and heterointerface co-boosted Zn2+ (De)intercalation kinetics in VO2 for ultra-efficient aqueous zinc-ion batteries

Abstract

In this study, we demonstrated the co-modification of oxygen vacancies and heterojunctions in VO2(B) (VO–VO2/MXene) as a cathode material for zinc-ion batteries (ZIBs). VO2 nanobelts are uniformly distributed on MXene nanosheets, which providing complete electron transport channels during the insertion or de-insertion of Zn2+. The formation of oxygen vacancies provides additional active sites and enhances the conductivity of VO2. Density functional theory calculations reveal that the oxygen vacancies effectively facilitate reversible intercalation/deintercalation process, which results in rapid intra-crystal zinc ion diffusion. The combination of VO–VO2 with MXene introduces an interfacial electric field, ultimately leading to synergistic enhancement in electrochemical activity. The VO–VO2/MXene composite exhibits the highest specific capacity (287 mAh g−1) at 10 A g−1 and excellent cycling lifespan (253 mAh g−1 after 3000 cycles) for ZIBs. This work provides a reliable strategy for the co-modification of metal oxide electrodes with oxygen vacancies and heterostructures.