Candle Soot-Embedded\nElectrospun Carbon Nanofibers\nas a Flexible and Free-Standing Sulfur Host for High-Performance Lithium–Sulfur\nBatteries

Abstract

Lithium–sulfur batteries (LSBs) have gained considerable\nattention during the last few decades owing to their high energy density\nthan conventional Li-ion batteries. Apart from the various technical\nchallenges associated with LSBs, there is a need to eliminate the\nbinder, additive, and current collectors used in conventional cell\nfabrication to enhance the energy density of LSBs. Therefore, this\nwork reports a free-standing flexible cathode matrix synthesized by\nelectrospun nanofiber using candle soot (CS)-incorporated polyacrylonitrile\nto boost the performance of LSBs. Sulfur is incorporated into a free-standing\nCS-carbon nanofiber (CS-CNF) mat by a melt diffusion approach. This\nflexible free-standing architecture provides good mechanical and electrical\nproperties and also assists in suppressing the infamous shuttle effect\nof polysulfides. Further, its porous network helps to sustain the\nvolume variation arising during electrochemical redox reactions. A\ndetailed electrochemical study reveals that the interconnected nanofiber\narchitecture helps in high sulfur loading and shows excellent rate\nperformance and cyclability. The fabricated LSB with the CS (2 wt\n%)-CNF/S cathode delivers a high initial discharge capacity of 804\nmAh g^–1 at 0.5 A g^–1 over 200\ncycles of the charge–discharge cycle after the rate capability\nstudy. Further, the CS (2 wt %)-CNF/S cathode delivers a remarkable\nspecific capacity of 1190 mAh g^–1 at 0.1 A g^–1 and 865 mAh g^–1 after 400 cycles\nat a high current rate of 1 A g^–1. This study paves\nan innovative way to synthesize scalable and cost-effective procedures\nfor developing an excellent carbon nanofiber-based free-standing flexible\ncathode matrix for high-performance LSBs with higher sulfur loading\nfor commercial adoption.