Porous carbon nanofibers formed in situ by electrospinning with a volatile solvent additive into an ice water bath for lithium–sulfur batteries

Abstract

The in situ formation of polyacrylonitrile (PAN) nanofibers with a porous structure was achieved by electrospinning ternary PAN/N,N′-dimethylformamide (DMF)/chloroform (CHCl₃), and ternary PAN/DMF/tetrahydrofuran (THF) solution systems into a glass dish filled with ice water. These porous carbon nanofibers (pCNFs) are both mesoporous and microporous, and attained high specific surface areas without the requirement of physical or chemical activation, which is mainly due to the in situ evaporation of the volatile solvent additive and the dissolution of the solvent in the ice water bath. The synthesis process is simple and versatile. The effects of the precursor components, precursor concentration and the collection method on the morphology and size distribution of the fibers have been investigated. The obtained pCNFs with porous structures and large surface areas were then utilized as conductive matrices for sulfur (S) to form pCNFs/S nanocomposites. Electrochemical measurements show that the pCNFs/S nanocomposite can deliver ∼400 and ∼340 mA h g⁻¹ after 50 cycles and 100 cycles at 0.5 C, corresponding to 80.1% and 68% capacity retention with a high Coulombic efficiency, respectively.