Solvation Structure of Conjugated Organosulfur Polymers for Lithium- Sulfur Battery Cathodes

D Gayen and Y Schutze and S Groh and J Dzubiella, ACS APPLIED POLYMER MATERIALS, 5, 4799-4810 (2023).

DOI: 10.1021/acsapm.3c00379

Lithium-sulfur (Li/S) batteries constitute a promising,next-generation energy storage technology due to their high theoreticalenergy density and low cost. To increase sustainability, processability,and battery performance, conducting organic polymers have become afocus of research for the development of better cathode materials.Here, we investigate the solvation structure of a single conjugatedpoly(4-(thiophen-3-yl)benzenethiol) (PTBT) polymer as a high- potentialmacromolecular candidate for synthesizing optimized cathodes in Li/Sbatteries. Using molecular dynamics (MD) simulation with newly optimizedforce-field parameters, we examine the effects of polymer length andvarious molar fractions of the popular dimethoxyethane (DME) and dioxolane(DOL) solvents on the structure of the PTBT polymer at a temperatureof 300 K. We characterize basic polymeric properties as well as thecomposition-dependent solvent adsorption structure and thermodynamicsand uncover significant tunability by the solvent. Importantly, wefind an interesting cosolvency effect, namely that a solvent mixturecomposed of 25% DME and 75% DOL leads to maximum swelling behavior,which should be important for optimizing cathode fractality and permeabilityin applications. Our study thus reveals intriguing polymer- solventcorrelations and serves as an important prerequisite for future MDstudies of realistic polymeric cathode structures and processes, e.g.,toward charge transport in vulcanized (S-linked) network topologies.

Return to Publications page