Constructing a novel heterostructure of NiSe2/CoSe2 nanoparticles with boosted sodium storage properties for sodium-ion batteries

Abstract

Sodium-ion batteries (SIBs) are among the most promising technologies for large-scale clean electrical energy storage and conversion. Developing SIB anode materials, which pose the major limitation in achieving high performance, including transition metal selenides (TMSe) with high sodium storage capacities is currently the cutting-edge research. In this paper, heterostructured NiSe₂/CoSe₂ nanoparticles are successfully synthesized by simple thermal selenization of a heterojuncted Ni(OH)₂/Co(OH)₂ precursor obtained through one-step solvothermal co-precipitation. Electrochemical tests and DFT calculations as well as in situ XRD measurements are used for investigating the Na storage properties and understanding the underlying mechanism. It is found that the heterointerface formed at the crystalline planes of NiSe₂ and CoSe₂ significantly improves the electron conductivity and optimizes the Na species adsorption, which accelerates electrochemical reaction kinetics and thus improves pseudocapacitive contribution. Therefore, the as-prepared NiSe₂/CoSe₂ nanoparticles exhibit superior Na storage properties such as enhanced Na storage capacity and rate capability as well as exceptional cycling stability at ultra-high current density.