Highly Porous NiCoSe4 Microspheres as High‐Performance Anode Materials for Sodium‐Ion Batteries

Abstract Binary transition metal selenides have been more promising than single transition metal selenides as anode materials for sodium‐ion batteries (SIBs). However, the controlled synthesis of transition metal selenides, especially those derived from metal‐organic‐frameworks with well‐controlled structure and morphology is still challenging. In this paper, highly porous NiCoSe 4 @NC composite microspheres were synthesized by simultaneous carbonization and selenization of a Ni−Co‐based metal‐organic framework (NiCo‐MOF) and characterized by scanning electron microscopy, transition electron microscopy, X‐Ray diffraction, X‐Ray photoelectron spectroscopy and electrochemical techniques. The rationally engineered NiCoSe 4 @NC composite exhibits a capacity of 325 mAh g −1 at a current density of 1 A g −1 , and 277.8 mAh g −1 at 10 A g −1 . Most importantly, the NiCoSe 4 @NC retains a capacity of 293 mAh g −1 at 1 A g −1 after 1500 cycles, with a capacity decay rate of 0.025 % per cycle.