Bifunctional structure modulation of Sb-based sulfide for boosting fast and high-capacity sodium storage

Abstract

The practical application of alloy-type anodes for sodium-ion batteries with high capacity and high rate performance is severely hindered by their huge volume expansion and low electrical conductivity. Here, a bifunctional structure modulation strategy is proposed to achieve fast and high-capacity sodium storage by introducing Cr into high-capacity Sb₂S₃ to form an intercalative Cr–S unit, which can buffer the volume expansion and pulverization of Sb₂S₃. The synthesized CrSbS₃ with Cr–S supporting unit and Sb–S energy storage unit exhibits high specific capacity of 544 mA h g⁻¹ after 100 cycles at 0.2 A g⁻¹ and 100% capacity retention after 4600 cycles at 20 A g⁻¹. Meanwhile, in situ X-ray diffraction (XRD), Raman and ex situ transmission electron microscopy (TEM) reveal that the formation of dispersed Cr⁰ as well as NaCrS₂ effectively confines Na₃Sb during the reversible sodium storage process. The structure modulation strategy of introducing non-active transition metals for the preparation of alloy-conversion bimetallic sulfides provides new ideas for the design of high-capacity and high-rate sodium-ion battery anode materials.