Constructing a hollow microflower-like ZnS/CuS@C heterojunction as an effective ion-transport booster for an ultrastable and high-rate sodium storage anode

Abstract

Hierarchical heterostructure coupling metal sulfides with carbonaceous functional support are regarded as promising anode candidates for sodium-ion batteries (SIBs) owing to their rich diffusion channels and active sites for Na⁺-storage, as well as strong charge redistribution features between heterointerfaces. However, achieving superior rate behaviors and ultralong cycling life remains a key challenge. Herein, starting from a well-organized ZnO microflower template, a hollow microflower-like configuration of metal sulfide ZnS/CuS encapsulated in a polydopamine-derived carbon skeleton (denoted as ZnS/CuS@C) is developed. Benefiting from the strongly synergistic coupling effect of heterostructures, this architecture affords swift Na⁺ immigration and robust structural tolerance, as reflected by an impressive cycling life (reversible capacity of 389.4 mA h g⁻¹ with nearly 100% retention ratio after 700 long-term cycles at 2 A g⁻¹) and competitive rate capability (341.0 mA h g⁻¹ at 5 A g⁻¹ after 1330 cycles and 282.7 mA h g⁻¹ at an ultrahigh rate up to 10 A g⁻¹ even after 1750 cycles). Kinetics analysis and density functional theoretical calculations elucidate that the fabrication of the heterointerface could induce large pseudocapacitive behaviors and trigger ultrafast sodiation kinetics.