Impact of Carbon Porosity on Sulfur Conversion in Li-S Battery Cathodes in a Sparingly Polysulfide Solvating Electrolyte

Advancing the development of lithium-sulfur (Li-S) technology is advantageous for next generation secondary batteries to improve gravimetric and volumetric energy of established energy storage devices. In this regard, a sparingly PS solvating electrolyte based on sulfolane and hydrofluoroether is known as a promising concept to enhance the volumetric energy density by increasing the cycling stability. So far, little is known about the impact of the carbon porosity on the electrochemical sulfur utilization. Herein, carbon materials with varying pore diameter and architecture (micropores, mesopores and hierarchical pores) are studied as scaffold for Li-S cathodes using TMS/TTE electrolyte to obtain more insights into the relationship between the carbon scaffold porosity and the modified conversion mechanism of sparingly solvating electrolytes. The electrochemical evaluation under lean conditions (5 mu l mg(S)(-1)) revealed stable cycling performance for all Li-S cathodes. Using microporous electrodes, a reversible quasi-solid-state conversion is detected by an additional third discharge plateau being confirmed by cyclovoltammetry. GITT experiments give evidence that the carbon porosity impacts the reaction kinetics of the polysulfide conversion by using TMS/TTE electrolyte. Based on these findings, new mechanistic insights into the operation of Li-S batteries are provided by using sparingly solvating electrolytes.

Automated summary

Advancing the development of lithium-sulfur (Li-S) technology using sparingly solvating electrolytes shows promise in enhancing volumetric energy density. This study focused on the impact of carbon porosity on electrochemical sulfur utilization, revealing that carbon scaffold with varying pore diameter and architecture can influence the reaction kinetics of polysulfide conversion in Li-S batteries using TMS/TTE electrolyte.