Carbon capsule confined Sb2Se3 for fast Na+ extraction in sodium-ion batteries

Abstract

Pulverization is a common phenomenon of alloy-based anode materials during the sodiation/desodiation process and usually leads to sluggish Na⁺ insertion/extraction kinetics. Although many studies have reported how to avoid or inhibit the occurrence of this phenomenon, it is still a great challenge in the research on alloy-based anode materials. Herein, we have achieved fast Na⁺ extraction in an Sb₂Se₃ alloy anode by constructing uniform carbon capsule confined Sb₂Se₃ composites (SSCs). Further analysis results indicate that the fast Na⁺ extraction is attributed to the uniform carbon capsule confined Sb₂Se₃ structure. In this structure, the carbon capsule can suppress the huge volume change of Sb₂Se₃ during the Na⁺ insertion process and uniformly release stress during the Na⁺ extraction process, maintaining the stable electrode structure. Specifically, Sb₂Se₃ is in situ pulverized in the intact carbon capsule and maintains the original rod-like outline, which provides a stable and short Na⁺ extraction pathway, good electrical contact, and a stable SEI layer on the surface of the intact carbon capsule and inhibits the side reaction of Sb₂Se₃. Therefore, the SSC exhibits fast Na⁺ extraction with a high reversible capacity of 324 mA h g⁻¹ at 5 A g⁻¹. The capacity is still as high as 380 mA h g⁻¹ after 600 cycles at 2 A g⁻¹.