A MoS2@SnS heterostructure for sodium-ion storage with enhanced kinetics.

ABSTRACT

Layered metal sulphides are promising anode materials for sodium-ion batteries (SIBs) and capacitors owing to their distinctive crystal structures and large interlayer spacings, which are suitable for Na+ insertion/extraction. However, low electronic conductivity, sluggish ion transfer and large volume variation of metal sulphides during sodiation/desodiation processes have hindered their practical application. In this work, we report the construction of a walnut-like core-shell MoS2@SnS heterostructure composite as an anode for SIBs with high capacity, remarkable rate and superior cycling stability. Experimental observations and first-principles density functional theory (DFT) calculations reveal that the enhanced electrochemical performances can be mainly ascribed to the boosted charge transfer and ion diffusion capabilities at the heterostructure interface driven by a self-building internal electric field. Our findings herein may pave the way for the development of novel heterostructure composite materials for beyond lithium-ion batteries and capacitors.