Electrochemical impedance spectroscopy study of lithium–sulfur batteries: Useful technique to reveal the Li/S electrochemical mechanism

Abstract

Electrochemical impedance spectroscopy (EIS) study was done in order to go deeper into the electrochemical processes of Li/S battery in a common CR2032 coin-type cell. In order to separate the contributions of each electrode (i. e. lithium negative electrode and sulfur composite positive electrode), impedance measurements on symmetrical cells consisting of two previously cycled electrodes was used. This methodology enables to propose an overall interpretation of the different electrochemical phenomena present during cycling. Low temperature tests were also applied, which brought fruitful information concerning the kinetics of the reactions and allowed to confirm the chemical-physical interpretations performed on the cell cycled at 25°C.

Regulating adsorption ability toward polysulfides in a porous carbon/Cu3P hybrid for an ultrastable high‐temperature lithium–sulfur battery

“…The characteristic absorption peak at 450-470 nm is ascribed to polysulfides. 51 This peak disappeared in the Li 2 S 6 solution absorbed by RFPC and RFPC/Cu 3 P. Compared with RFPC, the Li 2 S 6 solution absorbed by RFPC/Cu 3 P has a significantly weaker absorption, indicating that Cu 3 P can absorb polysulfides effectively. Thus, the PC/Cu 3 P hybrids designed in this study are suitable for use as the host material for sulfur.…”

“…The second semicircle that arose in the medium corresponds to the chargetransfer resistance (R ct ) of polysulfides dissolved in the electrolyte. 51 The inclined line at the low frequency represents Warburg impedance. As shown in Table S1, RFPC/Cu 3 P/S has an R s value of 3.4 Ω, which is lower than the R s value of RFPC/S (3.6 Ω), which is believed to be due to the larger specific area, the superior microstructure of RFPC/Cu 3 P/S, and the presence of copper in RFPC/Cu 3 P/S.…”

Open data model parameterization of a second-life Li-ion battery

“…This impedance can, then, be represented by electrical elements, with varying degrees of accuracy and performance. Good examples of EIS being used to parameterize an EEC model can be found in [18,[42][43][44].…”

The Pitfalls and Opportunities of Impedance Spectroscopy of Lithium Sulfur Batteries

“…That is where the concentration of polysulfides reaches a maximum, before Li 2 S deposition begins. [40,42,48,49] Through the low voltage plateau the resistance decreases, although it never reaches the initial value, suggesting that some dissolved polysulfides are permanently lost in the electrolyte, that is, stored in the separator pores. The electrolyte resistance trend continues with this middle of discharge (or charge) peak trend throughout cycling.…”

“…After the measurements have been conducted, impedance spectra contributions are then usually evaluated and interpreted, which frequently involves fitting with an equivalent circuit. [16,17,19,20,[40][41][42] Due to possible ambiguities, it is strongly recommended that at this point one envisions which processes are taking place in the cell in question. For example, if we have a porous carbon cathode in contact with a polysulfide solution in the electrolyte, we expect a limited number of possible impedance contributions.…”