title: Decomposition of Imidazolium-Based Ionic Liquids in Contact with Lithium Metal.
abstract: Ionic liquids (ILs) are considered to be suitable electrolyte components for lithium-metal batteries. Imidazolium cation based ILs were previously found to be applicable for battery systems with a lithium-metal negative electrode. However, herein it is shown that, in contrast to the well-known IL N-butyl-N-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide ([Pyr14][TFSI]), 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2MIm][TFSI]) and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C4MIm][TFSI]) are chemically unstable versus metallic lithium. A lithium-metal sheet was immersed in pure imidazolium-based IL samples and aged at 60 °C for 28 days. Afterwards, the aged IL samples were investigated to deduce possible decomposition products of the imidazolium cation. The chemical instability of the ILs in contact with lithium metal and a possible decomposition starting point are shown for the first time. Furthermore, the investigated imidazolium-based ILs can be utilized for lithium-metal batteries through the addition of the solid-electrolyte interphase (SEI) film-forming additive fluoroethylene carbonate.
authors.affiliation: Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149, Münster, Germany.|MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Paulo
authors.initials: P
authors.lastname: Schmitz
authors.affiliation: Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149, Münster, Germany.|MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Rene
authors.initials: R
authors.lastname: Jakelski
authors.affiliation: Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149, Münster, Germany.|MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Marcelina
authors.initials: M
authors.lastname: Pyschik
authors.affiliation: Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149, Münster, Germany.|MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Kirsi
authors.initials: K
authors.lastname: Jalkanen
authors.affiliation: MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Nowak
authors.affiliation: Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149, Münster, Germany.|MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.|Helmholtz Institute Münster, IEK-12, Forschungszentrum Jülich GmbH, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Winter
authors.affiliation: Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, 48149, Münster, Germany.|MEET Battery Research Center, University of Münster, Corrensstrasse 46, 48149, Münster, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Bieker
mesh_terms: D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; D008094:Lithium
keywords: aging; electrochemistry; interfaces; ionic liquids; lithium