MXene conversion to V₂S₃ heterostructure in CS₂ ambient: A novel approach for sodium-ion battery anodes

The abundant and wide distribution of sodium makes sodium-ion batteries (SIBs) one of the most promising battery technologies to supplement the current lithium-ion batteries in large-scale energy storage. However, the available anode materials are still far from satisfactory to enable the high-performance operation of SIBs. Here, a V₂S₃@C@V₂S₃ heterostructure anode is developed by one-step in-situ conversion of V₂CT_x MXene in CS₂ ambient. The resultant electrode has abundant heterointerfaces and controllable V₂S₃ crystallinity and size. In this unique design, the carbon interlayer in the anode behaves like a flexible conductive support and an anchoring network. The ultrathin V₂S₃ nanosheets and the V₂S₃–C heterointerfaces enhance the Na⁺ adsorption and migration abilities, thus simultaneously mitigating the low conductivity, structural degradation, and sluggish kinetics of V₂S₃. As a result, this V₂S₃@C@V₂S₃ anode achieves a highly reversible capacity (628 mAh/g at 0.1 A/g), excellent rate performance (477 mAh/g at 10A/g), and impressive cycling stability (2000 cycles at 20 A/g, record-high value). This performance is far better than the parent MXene phase. Considering the rich compositional diversity of MXene, the in-situ conversion strategy developed here can be extended to construct a wide range of high-performance electrode materials for advanced batteries.