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Capacitive Performance of Water-in-Salt Electrolyte in Supercapacitors: a Simulation Study

preprint
revised on 11.09.2018, 13:51 and posted on 11.09.2018, 14:16 by Zhujie Li, Guillaume Jeanmairet, Trinidad Mendez-Morales, Benjamin Rotenberg, Mathieu Salanne
Water-in-salts is a new family of electrolytes with very promising electrochemical properties for energy storage applications. Despite several studies involving them inside Li-ion batteries and supercapacitors, their interfacial properties remain largely unknown. Here we simulate the interface between electrified graphite electrodes and a highly concentrated waterin- salt (where the salt is Bis(trifluoromethane)sulfonimide lithium, LiTFSI) using constant applied potential molecular dynamics. We show that the capacitance differs markedly between the positive and the negative electrodes, which is due to the large asymmetry in size (and
shape) between the ions. By using importance sampling, we further investigate the changes in the structure of the salt at the interface and we observe that large variations occur, that are at
the origin of a series of peaks in the differential capacitance.

Funding

ANR-10-LABX-0076, ERC 771294, GENCI 2018--A0040910463

History

Email Address of Submitting Author

mathieu.salanne@sorbonne-universite.fr

Institution

Sorbonne Université

Country

France

ORCID For Submitting Author

0000-0002-1753-491X

Declaration of Conflict of Interest

No conflict of interest

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