Constructing nitrogen doped carbon coated CuFeSe2/Cu2Se polyhedrons with heterostructure interface as advanced anode for sodium storage

Transition metal selenides (TMSes), such as bimetallic selenides, are potential anodes for sodium-ion batteries (SIBs) because of their satisfied redox performances. Nevertheless, the sluggish electrochemical reaction rate and large volume expansion hinder their widespread application. To solve these disadvantages, constructing heterostructure and hollow structure are considered effective strategies. In this work, a polyhedron-templated approach is developed to synthesize uniform Cu 2 O polyhedrons, which are subsequently converted into nitrogen-doped carbon coated CuFeSe 2 /Cu 2 Se (Cu-Fe-Se@NC) via solvent thermal and annealing method. The constructed abundant heterointerfaces accelerate Na + adsorption, while the unique hollow core-shell structure effectively relieves volume expansion. Furthermore, density functional theory (DFT) calculation results indicated that the Na adsorption energies of Cu-Fe-Se@NC were higher than those of CuFeSe 2 @NC and Cu 2 Se@NC. As a result, the Cu-Fe-Se@NC anode exhibited remarkable rate performance (303 mAh g −1 , 10 A g −1 ) and superior cycling stability. This work offers a practical pathway for designing high-performance TMSes anodes through strategic heterostructure and morphology control.