Tunable Surface Selenization on MoO2-Based Carbon Substrate for Notably Enhanced Sodium-Ion Storage Properties

Abstract

Transition metal chalcogenides with high theoretical capacity are promising conversion-type anode materials for sodium ion batteries (SIBs), but often suffer from unsatisfied cycling stability (hundreds of cycles) caused by structural collapse and agglomerate. Herein, a rational strategy of tunable surface selenization on highly crystalline MoO2-based carbon substrate is designed, where the sheet-like MoSe(2)can be coated on the surface of bundle-like N-doped carbon/granular MoO(2)substrate, realizing partial transformation from MoO(2)to MoSe2, and creatingb-NC/g-MoO2@s-MoSe2-10 with robust hierarchical MoO2@MoSe(2)heterostructures and strong chemical couplings (Mo-C and Mo-N). Such well-designed architecture can provide signally improved reaction kinetics and reinforced structural integrity for fast and stable sodium-ion storage, as confirmed by the ex situ results and kinetic analyses as well as the density functional theory calculations. As expected, theb-NC/g-MoO2@s-MoSe2-10 delivers splendid rate capability and ultralong cycling stability (254.2 mAh g(-1)reversible capacity at 5.0 A g(-1)after 6000 cycles with approximate to 89.0% capacity retention). Therefore, the tunable surface strategy can provide new insights for designing and constructing heterostructures of transition metal chalcogenides toward high-performance SIBs.