Electrochemical oxidation endows VN/V3S4 heterostructure with high performance in aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZBs) draw significant attention owing to their unique advantages such as high safety, facile assembly, and low cost, profiting from the intrinsic properties of water-based electrolytes and the zinc metal anode. However, cathode materials suffer from slow zinc ion diffusion and low electronic conductivity, thereby limiting the improvement of electrochemical performance. Herein, we proposed an advanced heterostructure composite consisting of vanadium nitride and V3S4 (VN/V3S4). Compared with pure V3S4, the VN/V3S4 composite can achieve preferable rate capability and cyclic durability. These improvements are attributed to the collaborative effect between V3S4 and VN, which could effectively reduce the diffusion energy barrier and enhance conductivity, as demonstrated by density functional theory (DFT) calculations. Moreover, to achieve high charge-storage performance, the VN/V3S4 heterostructure was activated using an in-situ electrochemical oxidational process. After electrochemical oxidation process, the formed O-VN/V3S4 is endowed with abundant active sites originating from the amorphous V2O5, while holds the advantages of VN/V3S4 heterostructure. As demonstrated by electrochemical tests, the O-VN/V3S4 cathode displayed outstanding rate capability and exceptional cyclic stability, in which a reversible capacity of 115.4 mA h g−1 can be sustained after 4000 cycles at 10 A g−1.