Construction of V1.11S2 flower spheres for efficient aqueous Zn-ion batteries

Aqueous zinc-ion batteries (AZIBs) have become a focus due to their high safety, low cost, and environmental protection. Vanadium-based materials are commonly used as cathodes in AZIBs. As technology improves, more types of vanadium-based materials are successfully synthesized and applied. To find more suitable cathode materials, we first investigated the utility of V1.11S2 spheres for AZIB cathodes, which were synthesized by a facile solvothermal method. Benefiting from the excellent morphology and stable chemical system, the electrode exhibits continuous capacity growth during the cycling process and maintains stability over a long period of time. In addition, it has an outstanding rate capability. Specifically, the capacity reaches 224.8 mAh g-1 at 0.1 A g-1 and increases from 39.1 to 51.4 mAh g-1 at 2 A g-1 after 2000 cycles. Such characteristics can be attributed to the continuous and slow activation of the electrode and the growth of the specific surface area due to the scattered nanosheets, which allows the electrolyte to fully penetrate into the material and expose more active sites. Meanwhile, the increased V1.11S2 layer spacing due to the embedding of water molecules can provide a wide channel for ion transport. This work may provide new ideas for the synthesis and development of vanadium-based materials used in AZIBs.