December 2013The “solid electrolyte interphase” (SEI) is a growing passivation layer on anodes in lithium ion battery systems. The composition of this lithium ion conducting surface film is experimentally not easy to analyse. An appropriate method for its analytical examination are the electron spectroscopy for chemical analysis (XPS/ESCA) and the secondary ion mass spectrometry (SIMS), for example. In the picture above the XPS depth profiles of a few characteristic elements are shown for a lithium foil, which was stored in a 1 M LiTFSI (Lithium Bis(Trifluoromethansulfonyl)Imide) solution in DOL (1,3-Dioxolane) for 24 h. Extracting the binding energies from the XPS spectra we can establish a model of the SEI layer structure (lower part of the picture). As a main part of the SEI lithium hydroxide can be identified followed by a lithium fluoride layer. In direct contact with the electrolyte, we find organic compounds consisting mainly of alkoxides, carbonates, and carbides. (Picture submitted by Carsten Fiedler.) https://www.uni-giessen.de/en/faculties/f08/departments/physchem/janek/gallerypotm/pom2013/december-2013/viewhttps://www.uni-giessen.de/@@site-logo/logo.png
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December 2013
The “solid electrolyte interphase” (SEI) is a growing passivation layer on anodes in lithium ion battery systems. The composition of this lithium ion conducting surface film is experimentally not easy to analyse. An appropriate method for its analytical examination are the electron spectroscopy for chemical analysis (XPS/ESCA) and the secondary ion mass spectrometry (SIMS), for example. In the picture above the XPS depth profiles of a few characteristic elements are shown for a lithium foil, which was stored in a 1 M LiTFSI (Lithium Bis(Trifluoromethansulfonyl)Imide) solution in DOL (1,3-Dioxolane) for 24 h. Extracting the binding energies from the XPS spectra we can establish a model of the SEI layer structure (lower part of the picture). As a main part of the SEI lithium hydroxide can be identified followed by a lithium fluoride layer. In direct contact with the electrolyte, we find organic compounds consisting mainly of alkoxides, carbonates, and carbides. (Picture submitted by Carsten Fiedler.)
