writer：16. J. Ma, J. Fan, S. Chen, X. Yang, K. N. Hui, H. Zhang, C. W. Bielawski, J. Geng
keywords：sulfur copolymers, graphene, covalent binding, cathode kineties, lithium-sulfur batteries
source：期刊
Issue time：2019年
Lithium-sulfur (Li-S) batteries have received significantattention due to the high theoretical specific capacity of sulfur (1675 mA h g-1). However, the practicalapplications are often handicapped by sluggish electrochemical kinetics and the“shuttle effect” of electrochemical intermediate polysulfides. Herein, we proposean in-situ copolymerization strategy for covalently confining a sulfur-containingcopolymer onto reduced graphene oxide (RGO) to overcome the aforementionedchallenges. The copolymerization was performed by heating elemental sulfur andisopropenylphenyl-functionalized RGO to afford a sulfur-containing copolymer, i.e., RGO-g-poly(S-r-IDBI), which isfeatured with a high sulfur content and uniform distribution of the poly(S-r-IDBI)on RGO sheets. The covalent confinement of poly(S-r-IDBI) onto RGO sheets notonly enhances the Li+ diffusion coefficientsby nearly one order of magnitude, but also improves the mechanical propertiesof the cathodes and suppresses the shuttle effect of polysulfides. As a result,the RGO-g-poly(S-r-IDBI) cathode exhibits an enhanced sulfur utilization rate (10%higher than elemental sulfur cathode at 0.1 C), an improved rate capacity (688mA h g-1 for RGO-g-poly(S-r-IDBI)cathode vs. 400 mA h g-1 for elemental sulfur cathodeat 1 C), and high cycling stability (a capacity decay of 0.021% per cycle, lessthan one tenth of that measured for elemental sulfur cathode).