Understanding the Reaction Steps Involving Polysulfides in 1 M LiTFSI in TEGDME : DOL Using Cyclic Voltammetry Experiments and Modelling

International audienceThe reaction mechanisms of polysulfides in the electrolytes of lithium sulfur (Li-S) batteries are known to be complex. These reaction mechanisms may also change with the electrolyte used. Understanding the reaction steps of the polysulfides in a Li-S battery electrolyte is important to assess the underlying phenomena behind the Li-S cell performance limitations. Here, we investigate the reaction steps of polysulfides in electrolyte solutions containing S-8, Li(2)S(8)and Li(2)S(6)in 1 M LiTFSI in TEGDME : DOL (v/v 1 : 1) (one of the most interesting electrolytes for use in Li-S batteries), using experimental cyclic voltammetry and a mathematical model. The mathematical model assists in understanding the reaction steps behind the characteristics changes of cyclic voltammograms (CVs) with the scan rate and polysulfides speciation. Our systematic study shows that the reaction steps conventionally used in Li-S battery models are not sufficient to simulate all the CV characteristics of the investigated electrolyte solutions