Sulfur-modified carbon nanotubes for battery application

Abstract

The aim of this work is to improve materials for battery electrodes by increasing their ionic conductivity using sulfur-modified carbon nanotubes. The motivation of the study is the need to increase the conductivity of sulfur electrode materials in high-energy-density batteries. Carbon nanotubes and jet-milled carbon nanotubes were chemically functionalized by highly oxidizing acid with peroxide, followed by addition of surfactant to reduce surface tension, allowing the stable aqueous dispersion of CNTs. Then solution containing sulfur was introduced, resulting in sulfur-modified carbon nanotubes. The materials were characterized using XRD, XPS, STEM, PSD, and EIS to determine their phasal composition, surface chemistry, morphology, particle size distribution, and electrochemical behavior. Also, atomistic modeling of sulfur incorporated into CNTs was performed to identify favorable configuration of functional groups and sulfur bonds at defect and edge sites, thus gaining atomic level insights complementing the experimental part. The results indicated successful integration of sulfur into the CNT framework, which significantly increased the ionic conductivity of the modified CNTs. These findings provide a feasible strategy for producing more conductive material for sulfur electrodes in batteries.