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Impact of carbon porosity on sulfur conversion in Li-S battery cathodes in a sparingly polysulfide solvating electrolyte

: Kensy, Christian; Schwotzer, Friedrich; Dörfler, Susanne; Althues, Holger; Kaskel, Stefan

Fulltext ()

Batteries & supercaps 4 (2021), No.5, pp.823-833
ISSN: 2566-6223
European Commission EC
H2020; 814471; LiSA
Lithium sulphur for SAfe road electrification
Journal Article, Electronic Publication
Fraunhofer IWS ()
lithium sulfur battery; cathode materials; carbon porositiy variation; sparingly solvating electrolyte; mechanistic insight

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.