Design of an ultra-stable Sb2Se3 anode with excellent Na storage performance

Abstract Owing to the high theoretical capacity, Sb2Se3 has been regarded as one of the best choices for Sodium-ion batteries (SIBs) anode materials. However, Sb2Se3 anode suffers from huge volume change with poor electrode structure stability, resulting in limited cycling and rate performance. Herein, inspired by the formation of inclusion complex an effective strategy for improving unstable molecules in biological fields, we encapsulate Sb2Se3 in capsular carbon shell via a hydrothermal and calcinations process. Furthermore, by adjusting the thickness of the capsule carbon shell, an ultra-stable Sb2Se3 electrode structure is realized. Equipped with this ultra-stable electrode structure, Sb2Se3 anode exhibits high capacity of 475 mA h g−1 at 2 A g−1 even after 600 cycles, showing compelling advantage on Na storage performance compared to other reported Sb-based anode materials. The analysis results indicate that the intact capsular carbon shell can effectively remit huge volume change of Sb2Se3, and act like a reaction vessel in which the sodiation/desodiation reaction of Sb2Se3 is carried out regularly. Therefore, this ultra-stable electrode provides stable redox reactions, easy charge transfer and fast sodium ion diffusion, resulting in excellent Na storage performance of Sb2Se3 anode.