N-doped one-dimensional carbon framework embedded with CoSe2 nanoparticles as superior electrode for advanced sodium ion storage

Cobalt selenide (CoSe2) is acknowledged as a negative electrode material for sodium-ion batteries (SIBs) due to its high theoretical capacity. However, the significant volume change and inadequate electrochemical performance during charge and discharge processes have limited its practical use in batteries. In this investigation, a straightforward and practical electrospinning method combined with selenization reaction was utilized to fabricate CoSe2 nanoparticles enclosed in nitrogen-doped carbon nanofibers with a three-dimensional self-supporting network structure (CoSe2/N-PCNFs). The CoSe2/N-PCNFs electrode has self-supporting and high conductivity properties, as an anode material for sodium-ion batteries, the discharge capacity of the composite material can reach 450.1 mAh/g after 100 cycles at a current density of 0.2 A/g, and can still maintain a large discharge capacity of 396.9 mAh/g after 500 cycles at a high current density of 1 A/g. The outstanding electrochemical performance is mainly attributed to the superior specific surface area, controllable porous structure, and high pore volume of CoSe2/N-PCNFs Experimental and density functional theory calculations both indicate that the heterojunction interface between CoSe2 and nitrogen-doped carbon can not only promote the adsorption of Na+, but also facilitate electron transfer to significantly improve the rate capability of the material.