KIT | KIT-Bibliothek | Impressum | Datenschutz

Influence of Residual Water Traces on the Electrochemical Performance of Hydrophobic Ionic Liquids for Magnesium‐Containing Electrolytes

Elkhafif, Omar W.; Hassan, Hagar K. 1; Ceblin, Maximilian U.; Farkas, Attila; Jacob, Timo 2
1 Karlsruher Institut für Technologie (KIT)
2 Helmholtz-Institut Ulm (HIU), Karlsruher Institut für Technologie (KIT)

Abstract:

A trace amount of water is typically unavoidable as an impurity in ionic liquids, which is a huge challenge for their application in Mg-ion batteries. Here, we employed molecular sieves of different pore diameters (3, 4, and 5 Å), to effectively remove the trace amounts of water from 1-methyl-1-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPip-TFSI) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI). Notably, after sieving (water content <1 mg ⋅ L$^{−1}$), new anodic peaks arise that are attributed to the formation of different anion-cation structures induced by minimizing the influence of hydrogen bonds. Furthermore, electrochemical impedance spectroscopy (EIS) reveals that the electrolyte resistance decreases by ∼10 % for MPPip-TFSI and by ∼28 % for BMP-TFSI after sieving. The electrochemical Mg deposition/dissolution is investigated in MPPip-TFSI/tetraglyme (1 : 1)+100 mM Mg(TFSI)$_2$+10 mM Mg(BH$_4$)$_2$ using Ag/AgCl and Mg reference electrodes. The presence of a trace amount of water leads to a considerable shift of 0.9 V vs. Mg$^{2+}$/Mg in the overpotential of Mg deposition. In contrast, drying of MPPip-TFSI enhances the reversibility of Mg deposition/dissolution and suppresses the passivation of the Mg electrode.


Verlagsausgabe §
DOI: 10.5445/IR/1000161535
Veröffentlicht am 21.08.2023
Cover der Publikation
Zugehörige Institution(en) am KIT Helmholtz-Institut Ulm (HIU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2023
Sprache Englisch
Identifikator ISSN: 1864-5631, 1864-564X
KITopen-ID: 1000161535
HGF-Programm 38.02.02 (POF IV, LK 01) Components and Cells
Erschienen in ChemSusChem
Verlag Wiley-VCH Verlag
Band 16
Heft 19
Seiten Art.-Nr.: e202300421
Vorab online veröffentlicht am 20.06.2023
Schlagwörter ionic liquids, molecular sieves, trace water, electrochemical impedance spectroscopy, Mg deposition
Nachgewiesen in Dimensions
Scopus
Web of Science
KIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft
KITopen Landing Page