Electrochemical Lithiation of Covalently Bonded Sulfur in Vulcanized Polyisoprene

We report the synthesis of vulcanized polyisoprene (SPIP) nanowires and an investigation of the electrochemical lithiation mechanism of the covalently bonded sulfur bridges in SPIP. Electrochemical analysis demonstrates that the sulfur chains in SPIP have distinct electrochemical signatures from those that are characteristic of bulk elemental sulfur. The cyclic voltammetry and galvanostatic cycling data show a distinct multistep charge transfer process and solid-state lithium sulfur reaction behavior, and it is clear that this new material provides a promising basis for the development of cathodes for rechargeable batteries. Chemical changes due to the lithiation process are studied using Raman and X-ray photoelectron spectroscopy, on the basis of which new lithiation mechanisms of covalently bonded sulfur are proposed.