Heterostructure of Hollow MoSe2@CoSe for Stable Sodium Storage

Abstract

Transition metal selenides (TMSs) with excellent redox reversibility and high capacity have been considered as potential anodes for sodium-ion batteries (SIBs). However, low intrinsic conductivity and volume expansion of TMSs seriously hinder practical application. Herein, an exquisite hierarchical heterostructure of bimetallic selenide of MoSe2@CoSe has been fabricated by simple two-step solvothermal method. The hollow structure of CoSe could provide buffer space for avoiding volume expansion during discharge/charge process. Moreover, the heterojunction of MoSe2@CoSe can effectively increases storage sites and shorten migration path of Na+. As anode for SIBs, MoSe2@CoSe presents superior cycle stability (capacity retention of 99.6% after 3000 cycles), as well as splendid rate capability (410 mAh g-1 at 10 A g-1). Multistep redox reaction mechanism reactions of MoSe2@CoSe for sodium storage has been detailed discussed. Prospectively, transition metal selenides with heterojunction hollow nano-architectures would be an effective strategy to boost long-life stability and capacity of sodium storage performance.