DMSO-assisted copolymerization of acetone and sulfur and its application as a Li–S battery cathode

Ionics, vol.1, no.1, pp.1-10, 2026 (Peer-Reviewed Journal)

There is an ongoing pursuit of new chemistries to advance lithium–sulfur (Li–S) battery technologies. Among these,

electroactive sulfur-containing polymers have attracted significant interest. Here, we report a simple and novel synthesis

route for producing a sulfur-rich polymer, acetone polysulfide (AcPS), using acetone, elemental sulfur, and dimethyl

sulfoxide (DMSO) as starting materials. The reaction is performed in sealed vials at a moderate temperature of 130 °C,

yielding organosulfur polymers containing carbonyl groups, condensation-derived conjugated carbon structures, and sulfur

bridges between organic segments, with polymerized sulfur contents as high as ~ 59 wt%. Structural analyses confirm the

formation of amorphous sulfur–carbonyl polymer networks without detectable crystalline sulfur domains. Electrochemical

evaluation demonstrates that AcPS is active as a Li–S cathode material. In an optimized configuration employing a

conductive carbon-coated separator, slurry-coated AcPS cathodes deliver a sulfur-specific discharge capacity of ~ 615

mAh g⁻¹ at 0.2 C. Coulombic efficiency remains modest, stabilizing at approximately 90%, which is attributed to the

dissolution of electroactive polymer-derived fragments and their transient interfacial accumulation on the Li anode, as

supported by shuttle-current analysis and GITT-EIS. DOL/DME extraction further supports this interpretation, as removal

of some soluble sulfur-containing polymer fractions suppresses the pronounced charge/discharge imbalance, causing the

Coulombic efficiency to approach unity. Beyond materials development, this work also introduces a practical diagnostic

rationale to distinguish conventional polysulfide shuttling from the migration of soluble polymer-derived redox-active

species in Li–S cells.