Candle Soot-Embedded Electrospun Carbon Nanofibers as a Flexible and Free-Standing Sulfur Host for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries ( LSBs) have gained considerable attention during the last few decades owing to their high energy density than conventional Li-ion batteries. Apart from the various technical challenges associated with LSBs, there is a need to eliminate the binder, additive, and current collectors used in conventional cell fabrication to enhance the energy density of LSBs. Therefore, this work reports a free-standing flexible cathode matrix synthesized by electrospun nanofiber using candle soot (CS)-incorporated polyacrylonitrile to boost the performance of LSBs. Sulfur is incorporated into a free-standing CS-carbon nanofiber (CS-CNF) mat by a melt diffusion approach. This flexible free-standing architecture provides good mechanical and electrical properties and also assists in suppressing the infamous shuttle effect of polysulfides. Further, its porous network helps to sustain the volume variation arising during electrochemical redox reactions. A detailed electrochemical study reveals that the interconnected nanofiber architecture helps in high sulfur loading and shows excellent rate performance and cyclability. The fabricated LSB with the CS (2 wt %)-CNF/S cathode delivers a high initial discharge capacity of 804 mAh g(-1) at 0.5 A g(-1) over 200 cycles of the charge-discharge cycle after the rate capability study. Further, the CS (2 wt %)-CNF/S cathode delivers a remarkable specific capacity of 1190 mAh g(-1) at 0.1 A g(-1) and 865 mAh g(-1) after 400 cycles at a high current rate of 1 A g(-1). This study paves an innovative way to synthesize scalable and cost-effective procedures for developing an excellent carbon nanofiber-based free-standing flexible cathode matrix for high-performance LSBs with higher sulfur loading for commercial adoption.