MXene-Stabilized VS Nanostructures for High-Performance Aqueous Zinc Ion Storage.

Aqueous zinc-ion batteries (AZIBs) based on vanadium oxides or sulfides are promising candidates for large-scale rechargeable energy storage due to their ease of fabrication, low cost, and high safety. However, the commercial application of vanadium-based electrode materials has been hindered by challenging problems such as poor cyclability and low-rate performance. To this regard, sophisticated nanostructure engineering technology is used to adeptly incorporate VS nanosheets into the MXene interlayers to create a stable 2D heterogeneous layered structure. The MXene nanosheets exhibit stable interactions with VS nanosheets, while intercalation between nanosheets effectively increases the interlayer spacing, further enhancing their stability in AZIBs. Benefiting from the heterogeneous layered structure with high conductivity, excellent electron/ion transport, and abundant reactive sites, the free-standing VS/TiCT composite film can be used as both the cathode and the anode of AZIBs. Specifically, the VS/TiCT cathode presents a high specific capacity of 285 mAh g at 0.2 A g. Furthermore, the flexible Zn-metal free in-plane VS/TiCT//MnO/CNT AZIBs deliver high operation voltage (2.0 V) and impressive long-term cycling stability (with a capacity retention of 97% after 5000 cycles) which outperforms almost all reported Vanadium-based electrodes for AZIBs. The effective modulation of the material structure through nanocomposite engineering effectively enhances the stability of VS, which shows great potential in Zn storage. This work will hasten and stimulate further development of such composite material in the direction of energy storage.