Carbon reduction assist structured preparation stable three-dimensional V6O13 for durable aqueous zinc-ion batteries

Abstract

Among various zinc-ion batteries (ZIBs) cathodes, vanadium-based oxides have received a great deal of research due to their high theoretical specific capacity. However, the severe problem of dissolution and sluggish kinetics of Zn2+ diffusion in vanadium-based oxides limit their further development as cathode materials for ZIBs. Herein, a novel monoclinic V6O13 nanoflowers (VONs) cathode is synthesized via an in-situ surface carbon reduction method from orthorhombic V2O5 at specific temperature. Benefiting from the intrinsic open tunnel-like structure and mixed states V4+/V5+ of V6O13, which are beneficial to facilitate the diffusion of Zn2+ and improve electronic conductivity of VONs. In addition, the dissolution of vanadium in VONs is suppressed remarkably. Based on the synergy of the advantages, the ZIBs with VONs electrode show excellent electrochemical performances, including high specific capacity (420 mAh g−1 at 0.2 A g−1) and rate capability, especially long-term cycling stability (above 88.9% capacity retention after 6000 cycles). Moreover, the kinetics and mechanism of the Zn2+ storage and diffusion in VONs have been investigated by combining experimental data with density functional theory (DFT) calculations. This in-situ preparation strategy provides a new approach to regulate the structure and phase of vanadium-based oxides to meet the requirements of high-performance ZIBs.