Design of sulfur cathode with 1-D carbon nanostructures for high-performance lithium-sulfur batteries

Abstract

In order to satisfy growing demands for electronic devices such as electric vehicles or energy storage systems, batteries with higher energy density and specific capacity are required. Lithium-sulfur (Li-S) batteries are one of the most promising with high energy density (~2600 $Wh$ $kg^{-1}$) and specific capacity (~1675 $mAh$ $g^{-1}$). Although Li-S batteries have these advantages, there are three big challenges to overcome, i) low electrical conductivity of sulfur, ii) volume change during cycles, and iii) loss of active material due to polysulfide shuttling effect. Number of studies have been done to mitigate these obstacles, usually by utilizing porous and conduct material such as carbon. Herein, we investigated free-standing hemp-derived carbon fiber (HCF) sheet as cathode material for high sulfur load. The HCF cathode had high sulfur loading of 10 $mg$ $cm^{-2}$ and areal capacity of 6.1 $mAh$ $cm^{-2}$. To improve electrical conductivity and sulfur utilizing, carbon nanofibers (CNFs) were added to HCF, fabricating HCF-CNF composite. The cathode had lower impedance and polarization during charge and discharge, showing improved electrochemical reaction.