Investigation of electrochemical and chemical processes occurring at positive potentials in “Water-in-Salt” electrolytes

Maffre M, Bouchal R, Freunberger SA, Lindahl N, Johansson P, Favier F, Fontaine O, Bélanger D. 2021. Investigation of electrochemical and chemical processes occurring at positive potentials in “Water-in-Salt” electrolytes. Journal of The Electrochemical Society. 168(5), 050550.

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Journal Article | Published | English
Author
Maffre, Marion; Bouchal, Roza; Freunberger, Stefan AlexanderIST Austria ; Lindahl, Niklas; Johansson, Patrik; Favier, Frédéric; Fontaine, Olivier; Bélanger, Daniel
Department
Abstract
Lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) based water-in-salt electrolytes (WiSEs) has recently emerged as a new promising class of electrolytes, primarily owing to their wide electrochemical stability windows (~3–4 V), that by far exceed the thermodynamic stability window of water (1.23 V). Upon increasing the salt concentration towards superconcentration the onset of the oxygen evolution reaction (OER) shifts more significantly than the hydrogen evolution reaction (HER) does. The OER shift has been explained by the accumulation of hydrophobic anions blocking water access to the electrode surface, hence by double layer theory. Here we demonstrate that the processes during oxidation are much more complex, involving OER, carbon and salt decomposition by OER intermediates, and salt precipitation upon local oversaturation. The positive shift in the onset potential of oxidation currents was elucidated by combining several advanced analysis techniques: rotating ring-disk electrode voltammetry, online electrochemical mass spectrometry, and X-ray photoelectron spectroscopy, using both dilute and superconcentrated electrolytes. The results demonstrate the importance of reactive OER intermediates and surface films for electrolyte and electrode stability and motivate further studies of the nature of the electrode.
Publishing Year
Date Published
2021-05-01
Journal Title
Journal of The Electrochemical Society
Volume
168
Issue
5
Article Number
050550
IST-REx-ID

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Maffre M, Bouchal R, Freunberger SA, et al. Investigation of electrochemical and chemical processes occurring at positive potentials in “Water-in-Salt” electrolytes. Journal of The Electrochemical Society. 2021;168(5). doi:10.1149/1945-7111/ac0300
Maffre, M., Bouchal, R., Freunberger, S. A., Lindahl, N., Johansson, P., Favier, F., … Bélanger, D. (2021). Investigation of electrochemical and chemical processes occurring at positive potentials in “Water-in-Salt” electrolytes. Journal of The Electrochemical Society. IOP Publishing. https://doi.org/10.1149/1945-7111/ac0300
Maffre, Marion, Roza Bouchal, Stefan Alexander Freunberger, Niklas Lindahl, Patrik Johansson, Frédéric Favier, Olivier Fontaine, and Daniel Bélanger. “Investigation of Electrochemical and Chemical Processes Occurring at Positive Potentials in ‘Water-in-Salt’ Electrolytes.” Journal of The Electrochemical Society. IOP Publishing, 2021. https://doi.org/10.1149/1945-7111/ac0300.
M. Maffre et al., “Investigation of electrochemical and chemical processes occurring at positive potentials in ‘Water-in-Salt’ electrolytes,” Journal of The Electrochemical Society, vol. 168, no. 5. IOP Publishing, 2021.
Maffre M, Bouchal R, Freunberger SA, Lindahl N, Johansson P, Favier F, Fontaine O, Bélanger D. 2021. Investigation of electrochemical and chemical processes occurring at positive potentials in “Water-in-Salt” electrolytes. Journal of The Electrochemical Society. 168(5), 050550.
Maffre, Marion, et al. “Investigation of Electrochemical and Chemical Processes Occurring at Positive Potentials in ‘Water-in-Salt’ Electrolytes.” Journal of The Electrochemical Society, vol. 168, no. 5, 050550, IOP Publishing, 2021, doi:10.1149/1945-7111/ac0300.

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