Introducing Ce ions and oxygen vacancies into VO2 nanostructures with high specific surface area for efficient aqueous Zn-ion storage

Positive electrodes play a decisive role in exploring the Zn²⁺ storage mechanism and improving the electrochemical performance of aqueous Zn-ion batteries (AZIBs). Feasible design and preparation of cathode materials have been crucial for AZIBs in recent years. Herein, taking the advantage of the tunnel structure of VO₂, which can withstand volume change during charging/discharging, VO₂ doped with Ce ions is synthesized by a simple one-step hydrothermal method and oxygen vacancies are synchronously generated during synthesis. It delivers a capacity of 158.5 mAh g⁻¹ at the current density of 5 A g⁻¹ after 1000 cycles and exhibits an excellent energy density of 312.8 Wh kg⁻¹ at the power density of 142 W kg⁻¹. The structural modification and prospect of enhancing its conductivity by doping with rare-earth metals and introducing oxygen vacancies may aid in improving the stability of AZIBs in the future.