Scalable and economical production of oxygen deficient vanadium oxide with tunable vacancies concentration for bendable zinc ion batteries

Although vanadium oxides have high theoretical capacity and low cost, their practical application in aqueous zinc ion batteries (AZIBs) is bottlenecked by sluggish diffusion kinetics and capacity decline. Herein, the oxygen-deficient V2O5-x·nH2O (defined as VOd) with tunable oxygen vacancy concentration has been obtained via an economic and scalable method. The introduction of oxygen vacancies not only provides extra sites for Zn2+ storage, but also reduces the electrostatic barrier for Zn2+ intercalation, resulting in enhanced capacity and cycling stability. As a result, VOd cathode with proper amount of oxygen defect exhibits a high capacity of 415 mAh g−1 and energy density of 294 Wh kg−1 at 0.2 A g−1, estimating a roughly chemical costs of $64/kWH for VOd cathode. Besides, the VOd exhibits excellent stability at 20 A g−1 with average capacity decay of 0.004 % per cycle for 5000 cycles. Moreover, the bendable quasi-solid VOd//Zn battery maintains stable capacity of 200 mAh g−1 at 2 A g−1 even when repeatedly bending to straight angles. Therefore, the economical production of VOd cathode and construction of bendable quasi-solid battery provides a feasible way to boost the construction of efficient flexible energy storage devices and broadened application of AZIBs.