Polysulfide Speciation in Li–S Battery Electrolyte via In-Operando Optical Imaging and Ex-Situ UV-vis Spectra Analysis. Issue 9 (1st September 2022)

• Record Type: Journal Article
• Authors: Taiwo, Gbenga S.; Rashti, Ali; Mishra, Mritunjay; Yao, Koffi P. C.
• Is Part Of: Journal of the Electrochemical Society. Volume 169:Issue 9(2022)
• Publication Date: 2022-09-01
• Subjects: Li-S battery -- ex situ UV-vis -- polysulfide shuttle -- fully solvating -- sparingly solvating; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac8b3d
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Lithium sulfur (Li–S) batteries have received significant attention as one of the energy storage systems with excellent prospects for emerging applications due to their high energy density and low-cost. However, there are fundamental challenges impeding the commercialization of Li–S batteries. Notorious among those challenges is the "polysulfide shuttle" consisting of the dissolution into the electrolyte solvent and subsequent crossover to the anode of long-chain lithium polysulfides. Sparingly solvating electrolytes have been exploited as an approach to reduce the dissolution of polysulfides and thereby the shuttle effect. Using an optical in operando lithium-sulfur cell and ex situ UV–vis spectroscopy, we elucidate the speciation of polysulfides in fully and sparingly solvating electrolytes for Li–S batteries. Extensive literature meta-analysis reveals that the most unambiguous effect of sparingly solvating solvent is in improving the coulombic efficiency of sulfur-cells. Experimental optical imaging and UV–vis characterization elucidate a shift towards shorter-chain polysulfides in electrolytes with increasing lithium-salt concentration (more sparingly solvating). The shift to shorter-chain polysulfides corresponds to a reduction of polysulfide species participating in shuttling which corroborate the increased coulombic efficiency in sparingly-solvating electrolytes.