Carbon coated heterojunction CoSe 2 /Sb 2 Se 3 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 CoSe 2 /Sb 2 Se 3 heterojunction (CoSe 2 /Sb 2 Se 3 @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 CoSe 2 /Sb 2 Se 3 @C composite electrode. The highly pseudocapacitive Na + storage contribution is acquired due to the structural benefits of the heterojunction. Therefore, the CoSe 2 /Sb 2 Se 3 @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.