Experimental and Theoretical Analysis of Products and Reaction Intermediates of Lithium–Sulfur Batteries

Abstract

We investigated the reduction process of sulfur during cycling in a lithium−sulfur battery, correlating the output of ultraviolet−visible (UV−vis) spectroscopy and further characterization techniques with a theoretical model. The experimental setup allows carrying out UV−vis absorption measurements under argon atmosphere. The characteristic absorption bands (λ max ) of sulfur and dilithium sulfide dissolved in tetra-ethylene glycol dimethyl ether (TEGDME) are determined to be at 265 and 255 nm, respectively. Reference solutions of polysulfides diminish the λ max in the UV region with decrease of polysulfide order. The same tendency is observed in the range between 25−75% depth of discharge (DOD), caused by a progressive reduction of polysulfides in the electrolyte. At 425 and 615 nm, absorption bands are identified in the reference polysulfide solutions and also in the electrolyte at different DOD. These bands are interpreted as the characteristic bands of S 4 2− and S 3•−, and concentration changes of these species are determined semiquantitatively. The highest concentration of polysulfides is found at around 37% DOD (450 Ah•kg S −1 ). This was confirmed by the results of electrochemical impedance spectroscopy and computer simulations.

Application of a Sulfur Cathode in Nucleophilic Electrolytes for Magnesium/Sulfur Batteries

“…9, strong absorbance peaks appear at 240 nm and 265 nm for the S electrodes on Cu and SS, respectively, to indicate the dissolution of elemental sulfur based on the analysis of Mg/S and Li/S batteries. 8,36 The peaks for the S electrode on Cu (especially at 265 nm) are weaker than those on SS, which suggests that the concentration of dissolved S in the electrolyte is lower. Additionally, a weak peak appears at approximately 300 nm for the S electrode on Cu in Mg/S and Li/S cells, which is attributed to the S 6 2− anion.…”

“…Additionally, a weak peak appears at approximately 300 nm for the S electrode on Cu in Mg/S and Li/S cells, which is attributed to the S 6 2− anion. 36,37 The peak is not obvious for ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address.…”

Adsorption‐Catalysis Design in the Lithium‐Sulfur Battery

“…and accelerate the conversion of Li 2 S 2 /Li 2 S. [73,74] Moreover, deficiencies with the dangling bond can increase the adsorption sites which strengthen the adsorption ability. Therefore, surface engineering for material can improve the electrochemical features, providing a new design strategy for Li-S battery.…”

Quantitative Galvanostatic Intermittent Titration Technique for the Analysis of a Model System with Applications in Lithium−Sulfur Batteries

“…Impedance spectroscopy has also been used to evaluate the individual contributions from electrolyte resistance, charge transfer, ion diffusion and electrode surface layers, which in turn has been used to refine mechanistic models of Li−S cells,, as well as to investigate capacity fading . Other experimental techniques used to elucidate redox and diffusion properties in Li−S cells include XAS, in‐operando optical imaging of the temporal and spatial distribution of polysulfides, UV‐Vis spectroscopy, NMR, EPR/ESR,, XRD, Raman, HPLC, and gas evolution, among other electrochemical studies . The mechanism and kinetics of Li 2 S precipitation has been studied using chronoamperometry .…”