C–S Bonds in Sulfur-Embedded Graphene, Carbon Nanotubes, and Flake Graphite Cathodes for Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are excellent rechargeable battery candidates which are extraordinarily promising as they exhibit superior specific capacity and well-known energy density; they are cost-effective and environmentally benign. Nevertheless, a few technical issues pose a significant challenge on the path to industrial applications, namely, capacity fade and Coulombic efficiency decay, which are inherent in the soluble polysulfide shuttle effect during charge/discharge cycling. Carbon materials which have excellent conductive scaffold and flexible structure with a variety of morphologies can serve as a remedy to this issue. Herein, with a well-designed melt-diffusion procedure, we prepared three carbon-based sulfur-embedded cathodes with diverse structures [graphene, carbon nanotubes (CNTs), and flake graphite]. Sulfur loading varies between 60 and 73 wt %. Among these three carbon/S cathodes, beyond 100 cycles, the graphene/S cathode showed a discharge capacity of 840 mA h g–1 at 0.2 A g–1 cur...