Tunable CuS nanocables with hierarchical nanosheet-assembly for ultrafast and long-cycle life sodium-ion storage

Abstract

Transition-metal sulfides (TMSs) were demonstrated to be heartening anodes for sodium-ion batteries (SIBs) because of their alterable nanostructures, large theoretical capacity and environmental friendliness. Whereas, the relatively poor rate and cycling capability of TMSs still hinder the rapid development of their practical applications. Herein, a novel CuS nanocable self-assembled by hierarchical nanosheet is designed as SIB anodes, which delivers a large capacity (367 mAh g−1 at 5 A g−1), excellent rate capacity and cycle performance (213 mAh g−1 after 2000 cycles at 15 A g−1). The uniquely hierarchical nanostructure can both contribute more effective and durable active sites and shorter diffusion length of sodium ions/electrons. Besides, ex situ XRD, HRTEM and SAED reveal the phase transformation during sodiation process and the reaction mechanism of as-synthesized CuS nanocables. These results can offer new clues and inspirations to understand the relationship between the designed nanostructures and sodium storage behaviors of other TMSs.