Synergetic alloying-conversion-alloying multiple reaction mechanism of MXene@Sb/In2S3 heterostructure for improved Na+/K+ storage

Antimony-based materials, which have high capacities and moderate potentials, are seen as promising anode candidates for sodium-/potassium- ion batteries. However, they suffer from huge volume expansion and poor conductivity, leading to low structural stability and slow reaction kinetics. In this manuscript, 2D MXene nanosheets was firstly prepared as the supported substrate through HF free etching strategy of Ti₃AlC₂ bulk material. Then the final product of MXene@Sb/In₂S₃ heterostructure was synthesized by solvothermal method and the subsequent low temperature annealing process. The abundant oxygen-containing groups on the surface of MXene provide abundant nucleation sites for the homogeneous anchoring Sb³⁺/In³⁺and growth of Sb/In₂S₃ nanocrystals. Furthermore, the MXene@Sb/In₂S₃ heterostructure, with dispersed Sb/In₂S₃ nanocrystals on the MXene surface, greatly mitigate MXene nanosheet restacking, thereby exposing more active sites to the electrolyte. When used as the electrode materials for Na⁺/K⁺ batteries (SIBs /PIBs), MXene@Sb/In₂S₃ heterostructure presents excellent electrochemical and battery performance. In SIBs, it holds the capacity of 320mAh g⁻¹ at a current density of 1 A g⁻¹ 1000 cycles. In PIBs, MXene@Sb/In₂S₃ showed rate performance comparable to other reported potassium-electric materials of the same type and retained A reversible capacity of 185mAh g⁻¹ after 650 cycles at a constant current of 1 A g⁻¹. This design strategy provides a valuable guidance for the development of high-performance alloy-based and conversion-type anodes for energy storage devices.