Conductive Sulfur-Rich Copolymer Composites as Lithium–Sulfur Battery Electrodes with Fast Kinetics and a High Cycle Stability

Lithium–sulfur batteries are attracting significant attention due to their high specific capacity, reaching 1672 mAh g–1, but their practical applications are hindered by the inherent insulation of sulfur and slow electrochemical kinetics. To overcome these challenges, an in situ method to chemically attach graphene oxide to the surface of sulfur-rich copolymers is developed in this study. Herein, novel conductive sulfur-rich copolymer composites, cp(S-r-DIB)-Cy-rGO (cpSDG), with a high sulfur copolymerization degree of ca. 52 at % and excellent capacity rates of 1227 mAh g–1 at 0.1 C and 950 mAh g–1 at 1 C, have been obtained by covalently bonding cysteamine-functionalized reduced graphene oxide (Cy-rGO) to the surface of the sulfur-rich polymer matrix (cp(S-r-DIB)). Compared to a copolymer without Cy-rGO loading and pure sulfur cathodes, the composites display significant enhancements of lithium-ion diffusion coefficients and a higher cycling stability, with a capacity decay of only 0.06% per cycle.