Heterostructure of CoSe2@SnSe anode for high-rate performance sodium-ion battery

Abstract

Transition metal selenides (TMSs), as promising anode materials for sodium ion batteries (SIBs), still face sluggish Na⁺ diffusion kinetics and severe volume change, resulting in undesirable cycling stability and rate capability. Heterostructure construction is an effective method to improve sodium ion storage in TMSs. Herein, a hierarchical hollow heterostructure of CoSe₂@SnSe is precisely designed through a facile coprecipitation process followed by a selenization strategy. The heterostructure constructed by CoSe₂ and SnSe nanocrystals induces the formation of built-in electric fields and accelerates electron transfer and ion diffusion, thereby improving reaction kinetics significantly. When the as-prepared CoSe₂@SnSe composites are employed as anode materials of SIBs, there exhibit ultra-fast electrochemical reaction kinetics and outstanding cycling stability with a high capacity retention of 488.9 mAh g⁻¹ at a current density of 2.0 A g⁻¹ after 900 cycles. In addition, there still shows an exceptional rate capability of 409.5 mAh g⁻¹ at a high current density of 10 A g⁻¹. This work provides an effective method for the rational designing of heterostructure anode materials for high-performance SIBs.