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.