Multiple Heterointerfaces and Heterostructure Engineering in MXene@Co-P-S Hybrids Promote High-Performance Sodium-Ion...

In this paper, heterogeneous cobalt phosphosulfide (Co₄S₃/Co₂P) nanocrystals anchoring on few-layered MXene nanosheets (MXene@Co₄S₃/Co₂P) were prepared by in situ growth and the subsequent high-temperature phosphorization/sulfidation processes. Thanks to the synergistic effect and the abundant phase interfaces of Co₄S₃, Co₂P, and MXene, the electron transfer and Na⁺ diffusion processes were greatly accelerated. Meanwhile, the high electrical conductivity of MXene nanosheets and the heterogeneous structure of Co₄S₃/Co₂P effectively avoided the MXene restacking and the agglomeration of phosphosulfide particles, thus mitigating volumetric expansion during charging and discharging. The results show that the MXene@Co₄S₃/Co₂P heterostructure presents good rate capability (251.08 mAh g^-1 at 1 A g^-1) and excellent cycling stability (198.69 mAh g^-1 after 407 cycles at 5 A g^-1). Finally, the storage mechanism of Na⁺ in the heterostructure and the multistep phase transition reaction were determined by ex situ X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) analyses. This study provides a new perspective on the formation of metal phosphosulfide and MXene hybrids with multiple heterointerfaces as well as demonstrates MXene@Co₄S₃/Co₂P composites as the promising anode material in sodium-ion batteries.