Electrospinning synthesis of porous carbon nanofiber supported CoSe₂ nanoparticles towards enhanced sodium ion storage

CoSe₂-based anode materials are highly attractive for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, but the weak rate capability and rapid capacity fading hinder their practical application. Herein, porous carbon nanofiber supported CoSe₂ nanoparticles (denoted as CS@PCNFs) are designed and fabricated through electrospinning and subsequent heat treatment with PAN (polyacrylonitrile) as the carbon source and PMMA (polymethyl methacrylate) as the pore-forming agent to design the porous architecture of the carbon nanofibers and control the amount of CoSe₂ grains anchored on the fiber surface. Benefiting from the desired structural features including the large specific surface area, appropriate pore volume and robust structure stability, when examined as anode materials for SIBs, the as-prepared CS@PCNFs demonstrated excellent sodium-ion storage performances. Experimental results show that the CS@PCNFs with an optimized PAN/PMMA mass ratio of 6:4 can deliver a high reversible capacity of 413.6 mA h g⁻¹ at 0.2 A g⁻¹ after 150 cycles and an excellent rate capability of 401.5 mA h g⁻¹ at 2.0 A g⁻¹.