Electrochemical Activation in Vanadium Oxide with Rich Oxygen Vacancies for High-Performance Aqueous Zinc-Ion Batteries

Environmental concerns promote the development of sustainable energy storage devices. Resource-rich vanadium oxides with easily adjustable valence still exhibit unsatisfactory electrochemical performance stemming from poor electrical conductivity and friable structure as aqueous zinc-ion battery (AZIB) cathodes. Herein, vanadium oxide (VO-300) enriched with oxygen vacancies is acquired via a convenient solvothermal method in combination with subsequent heat treatment, which exhibits a remarkable rate performance of 411.98 mAh·g–1, and an excellent cycling life for 1500 cycles with 92.8% retention at 10 A·g–1. The enhanced electrochemical performances of VO-300 can be attributed to more oxygen vacancies, which provide more active sites for zinc-ion storage, expand layer spacing, and increase the conductivity of V2O5. More pivotal, the activation phenomenon is analyzed, and a two-carrier conversion insertion mechanism of H+ domination to Zn2+ domination is proposed. Based on this mechanism, the V2O5 is transformed into ZnxV2O5·nH2O as an active material for subsequent zinc-ion storage, leading to faster electrochemical kinetics. This work not only demonstrates the potential application of V2O5 as a zinc-ion cathode but also provides new insights into the zinc-ion storage mechanism.