Interlayer-expanded MoSe2/C superlattice hollow nanospheres as stable anodes for sodium/potassium ion batteries

Abstract

As a layered two-dimensional material, MoSe₂ exhibits interlayer-tunable properties and exceptional theoretical capacities, making it a promising candidate for sodium/potassium ion storage systems. Nevertheless, its inadequate conductivity and irreversible reactions during charge and discharge seriously affect its electrochemical performance. Herein, a hierarchical interlayer-expanded MoSe₂/C (IE-MoSe₂/C) hybrid architecture with interlinked hollow nanospheres is engineered via a two-stage fabrication process combining hydrothermal self-assembly and controlled pyrolysis. The interlayer spacing increases to 1.02 nm, which accelerates the transport of sodium and potassium ions. Additionally, the strong interface between carbon and MoSe₂ improves the conductivity, thereby enhancing the electrochemical kinetics of sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). On the other hand, the unique hierarchical IE-MoSe₂/C structure with hollow nanospheres can effectively mitigate variations in volume during cycling. Thus, IE-MoSe₂/C exhibits outstanding electrochemical characteristics as an anode material for SIBs and PIBs. Specifically, IE-MoSe₂/C exhibits better rate capability (98 mAh g⁻¹ at 20 A g⁻¹ in SIBs) and cycling performance (269/174 mAh g⁻¹ at 2.0/5.0 A g⁻¹ over 1100 cycles in SIBs and 133/96 mAh g⁻¹ at 1.0/2.0 A g⁻¹ over 1000 cycles for PIBs). Additionally, at 0.5C, the full cell of IE-MoSe₂/C||Na₃V₂(PO₄)₃ can display a consistent capacity of 93 mAh g⁻¹, demonstrating the potential for future practical applications.