Interleaved nanosheet MXene@CZTS heterostructure with reversible and stable capacity for sodium-ion batteries

Ti₃C₂T_x MXene, an emerging two-dimensional material, has garnered considerable attention as a promising material for sodium-ion batteries due to its excellent electrical conductivity, abundant surface functional groups, and unique layered structure. Often combined with other materials to construct heterostructures because of its relatively low theoretical capacity, metal sulfides, when subjected to highly selective and controllable multi-cation co-doping, can exploit the synergistic effects among different functional dopant atoms, achieving high charge storage, robust crystal structure, and superior sodium ion reaction kinetics simultaneously. In this study, monolayer Ti₃C₂T_x MXene nanosheets were obtained through etching and centrifugation, followed by the in-situ growth of Sn-Zn co-doped Cu₂ZnSnS₄ (CZTS) nanosheets via a simple hydrothermal reaction. The prepared MXene@CZTS heterostructure leverages the beneficial properties of each component, significantly enhancing the material's sodium ion storage capability. The results show that the specific capacity of MXene@CZTS anode material is 475.7 mAh g⁻¹ at 0.2 a g⁻¹ current density, and 332 mAh g⁻¹ after 1000 cycles at 2 a g⁻¹, with a coulombic efficiency approaching 100 %. It shows excellent sodium storage performance and stable reversible capacity. These excellent sodium storage characteristics make the material a strong candidate for sodium-ion battery anode materials.