Decomposition of Imidazolium‐Based Ionic Liquids in Contact with Lithium Metal. Issue 5 (20th February 2017)

• Record Type: Journal Article
• Authors: Schmitz, Paulo; Jakelski, Rene; Pyschik, Marcelina; Jalkanen, Kirsi; Nowak, Sascha; Winter, Martin; Bieker, Peter
• Is Part Of: ChemSusChem. Volume 10:Issue 5(2017)
• Page Start: 876
• Page End: 883
• Publication Date: 2017-02-20
• Subjects: aging -- electrochemistry -- interfaces -- ionic liquids -- lithium; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201601496
• Languages: English
• ISSNs: 1864-5631

Abstract

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. Abstract : Effects of surface exposure : The chemical instability of imidazolium‐based ionic liquids (ILs) in contact with lithium metal is discussed. After aging the ILs in contact with a lithium‐metal sheet, possible decomposition products are analyzed. Furthermore, stable cycling behavior in lithium‐metal batteries occurs through the addition of the solid–electrolyte interphase film‐forming additive fluoroethylene carbonate.