Carbon coated heterojunction CoSe2/Sb2Se3 nanospheres for high-efficiency sodium storage.

Multicomponent metal selenides with heterostructures are believed to effectively activate the surface pseudocapacitive contribution and improve the electrochemical dynamics, thus achieving high-performance anodes for sodium ion batteries (SIBs). Herein, a carbon coated CoSe2/Sb2Se3 heterojunction (CoSe2/Sb2Se3@C) is designed and constructed via an ion-exchange reaction between Co and Sb, and the subsequent selenization step. It is found that the hetero-structure and carbon shell effectively boost the charge transfer in the CoSe2/Sb2Se3@C composite electrode. The highly pseudocapacitive Na+ storage contribution is acquired due to the structural benefits of the heterojunction. Therefore, the CoSe2/Sb2Se3@C anode affords good cycling stability (264.5 mA h g−1 after 1000 cycles at 2 A g−1) and excellent rate capability (266.0 mA h g−1 at 5 A g−1). This study supplies a reference for developing an advanced anode with multicomponent and heterojunction structures for energy storage. [ABSTRACT FROM AUTHOR]