Effects of porous structure of carbon hosts on preparation and electrochemical performance of sulfur/carbon composites for lithium–sulfur batteries

Abstract

Three kinds of carbon hosts, Ketjenblack (KB, high surface area and porosity), black pearls 2000 (BP2000, high surface area and moderate porosity), and ordered mesoporous carbon nanospheres (OMCN, low surface area and porosity), have been used as conductive hosts in the sulfur/carbon (S/C) composite cathodes for lithium–sulfur (Li–S) batteries. To correlate the carbon properties (surface area and pore volume), the electrochemical performances of S/C composite cathodes with the same sulfur content (60 wt%) have been investigated in detail. S/KB and S/BP2000 composites with high surface porosity can provide more reactive sites for sulfur, which can result in increasing the utilization rate of sulfur, reducing the polarization, and improving the high-rate capability. Large pore volume can effectively capture the polysulfide species and improve easy passages for ion transport, which can promote long-term cycling stability and reduce the resistance of Li–S batteries.