Crosslinked Polypyrrole Grafted Reduced Graphene Oxide-Sulfur Nanocomposite Cathode for High Performance Li-S Battery

A novel ternary rGO/PPy/S nanocomposite possessing of a hierarchical nanostructure via incorporating the matrix of reduced graphene oxide (rGO) coated by polypyrrole (PPy) with sulphur was prepared by a facile one-pot in situ method. The chemical bonds exist between PPy and rGO through the formation of graphitic N and pyridine oxide N, and the CS, SC = S and SO chemical bonds form between rGO/PPy and S in the structure of the rGO/PPy/S material. The loading content of sulphur is 69.43 wt.% for the rGO/PPy/S sample. The rGO/PPy/S material exhibits a high performance when used as the cathode of Li-S battery. The initial and last discharge capacity arrived at 991.5 and 626.7 mAh g−1 at 1C with 400 cycles which is corresponding to the capacity retention ratio of 63.2%, indicating its very high cyclic stability. The discharge capacity of 537.4 mAh g−1 could be obtained at 5C and it maintained at 442.1 mAh g−1 after 400 cycles with the Coulombic efficiency of more than 90%, showing its excellent rate stability.