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Magnesium Polysulfides: Synthesis, Disproportionation, and Impedance Response in Symmetrical Carbon Electrode Cells
Author(s) -
Drvarič Talian Sara,
Vizintin Alen,
Bitenc Jan,
Aquilanti Giuliana,
RandonVitanova Anna,
Gaberšček Miran,
Dominko Robert
Publication year - 2021
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202100041
Subject(s) - polysulfide , chemistry , disproportionation , dielectric spectroscopy , electrolyte , inorganic chemistry , solubility , sulfur , carbon fibers , glassy carbon , magnesium , electrochemistry , cyclic voltammetry , electrode , organic chemistry , materials science , catalysis , composite material , composite number
Magnesium polysulfides have a key role during the redox reaction in magnesium‐sulfur batteries. However, kinetics of the Mg polysulfide disproportionation, transport, and solubility in electrolytes are rarely studied. To fill this gap, we here report the synthesis of different chain‐length Mg polysulfides and their characterization with 1 H NMR, ATR‐IR, and XANES spectroscopies. The tendency of polysulfides to disproportionate in solutions is confirmed with UV/Vis spectroscopy. To probe their reactivity and diffusivity, impedance spectroscopy is performed in symmetrical cells consisting of two planar glassy carbon or porous carbon electrodes containing Mg polysulfide catholyte. Several transport‐reaction parameters are obtained, such as exchange current densities, chemical diffusion coefficients, transference numbers of polysulfides, and conductivities. Moreover, we show that the solubility of Mg polysulfides in Mg(TFSI) 2 , MgCl 2 ether‐based electrolyte is affected at rather moderate concentration of polysulfides, thereby having an impact on the cell performance.