Application of In Operando UV/Vis Spectroscopy in Lithium-Sulfur Batteries

• Published in: ChemSusChem 2014-08, Vol.7 (8), p.2167-2175
• Main Authors: Patel, Manu U. M., Dominko, Robert
• Format: Article
• Language: English
• Subjects: Calibration; Electric Power Supplies; Electrochemistry; Lithium; Lithium - chemistry; polymers; Spectrophotometry, Ultraviolet; Spectrum analysis; Sulfides - chemistry; sulfur; Sulfur - chemistry; Ultraviolet radiation; UV/Vis spectroscopy
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201402215

Application of UV/Vis spectroscopy for the qualitative and quantitative determination of differences in the mechanism of lithium–sulfur battery behavior is presented. With the help of catholytes prepared from chemically synthesized stoichiometric mixtures of lithium and sulfur, calibration curves for two different types of electrolyte can be constructed. First‐order derivatives of UV/Vis spectra show five typical derivative peak positions in both electrolytes. In operando measurements show a smooth change in the UV/Vis spectra in the wavelength region between λ=650 and 400 nm. Derivatives are in agreement with derivative peak positions observed with catholytes. Recalculation of normalized reflections of UV/Vis spectra obtained in operando mode enable the formation of polysulfides and their concentrations to be followed. In such a way, it is possible to distinguish differences in the mechanism of polysulfide shuttling between two electrolytes and to correlate differences in capacity fading. As it happens: A newly developed method for the deconvolution of UV/Vis spectra back into concentrations enables the study of the polysulfide shuttle mechanism in the different environments of lithium–sulfur batteries. The method is used to systematically study two different electrolytes. It is possible to distinguish the differences in the mechanism of polysulfide shuttling between two electrolytes and to correlate differences in capacity fading.