Accelerated Synthesis of Inversely Vulcanized Polymers with Oligoethylene Unit Bearing Comonomer for Lithium–Sulfur Battery Application

Abstract

Lithium–sulfur (Li–S) batteries are considered a promising next-generation energy storage technology owing to their high theoretical capacity (1675 mAh·g⁻¹) and low cost. However, their practical deployment is hindered by the polysulfide shuttle effect and rapid capacity fading. Inverse vulcanization has emerged as an effective strategy to obtain sulfur-rich polymers that mimic the redox activity of elemental sulfur, yet many comonomers are excluded due to low boiling points or polarity mismatches, leading to premature homopolymerization or phase separation. This work overcomes these limitations through catalytic inverse vulcanization, producing polysulfidic copolymers bearing oligoethylene segments by reacting sulfur with triethyleneglycol dimethacrylate (TEGDMA) using zinc diethyldithiocarbamate (ZDEC) as a catalyst, commonly regarded as vulcanization accelerators. Spectroscopic and thermal analyses (FT-IR, Raman, XPS, XRD, DSC, TGA) confirm successful copolymer formation. Theoretical studies further show that the ZDEC activates sulfur, promoting efficient polymerization with TEGDMA. The resulting sulfur-rich copolymer is used as cathode active material in Li–S batteries, with multi-walled carbon nanotubes (MWCNTs) serving as a porous conductive host. SEM, TEM, and EDAX analyses reveal uniform dispersion and a sulfur-rich surface. Electrochemical testing demonstrates high initial capacity (1182.2 mAh·g⁻¹ at 0.1C), effective utilization of active material, stability over 100 cycles, and striking rate performance compared to conventional sulfur cathodes.