In-situ amorphous transformation of V2O5 in V2O5/V6O13 for aqueous zinc ion batteries with high capacity and long cycles

Rechargeable aqueous zinc-ion batteries (AZIBs) are attractive due to their superior safety, rich zinc resources, and cost-efficient. Vanadium-based oxides , as popular cathode materials , are inevitably subject to dissolution in aqueous solutions, and inherent low electrical conductivity and sluggish reaction kinetics, significantly impeding the performances in Zn 2+ storage. In this study, V 2 O 5 /V 6 O 13 composites are successfully prepared by a novel three-roll milling technique combined with high-temperature treatment to improve these shortcomings. The results demonstrate that the V 2 O 5 /V 6 O 13 electrode sustains excellent cycling (316.0 mAh g −1 at 5 A g −1 after 4000 cycles) and superior rate performance (186.69 mAh g −1 at 20 A g −1 ). Ex-situ characterization reveals that the mechanism involves the co-intercalation of H 2 O with Zn 2+ . It is found by testing in different electrolytes that V 2 O 5 is gradually amorphous in aqueous electrolyte during cycling, which greatly improves the structural stability and enhances the ability for capturing Zn 2+ . Moreover, it is demonstrated by calculations that a higher degree of amorphization promotes the adsorption of Zn 2+ . The present work provides a new idea for the development and mechanism explanation of high-performance AZIB materials.