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 have the potential to be used in Na+/K+ 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 twostage 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, the outstanding electrochemical characteristics of IE-MoSe2/C are achieved as anode materials 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, 133/96 mAh g-1 at 1.0/2.0 A g-1 over 1000 cycles for PIBs). Additionally, at 0.5C, the built 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.