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Spectroscopic characterization of the SEI layer formed on lithium metal electrodes in phosphonium bis(fluorosulfonyl)imide ionic liquid electrolytes
journal contribution
posted on 2018-02-21, 00:00 authored by Gaetan Girard, Matthias Hilder, Nicolas Dupre, Dominique Guyomard, Donato Nucciarone, Kristina Whitbread, Serguei Zavorine, Michael Moser, Maria ForsythMaria Forsyth, Douglas R MacFarlane, Patrick HowlettPatrick HowlettThe chemical composition of the solid electrolyte interphase (SEI) layer formed on the surface of lithium metal electrodes cycled in phosphonium bis(fluorosulfonyl)imide ionic liquid (IL) electrolytes are characterized by magic angle spinning nuclear magnetic resonance (MAS NMR), X-ray photoelectron spectroscopy (XPS), fourier transformed infrared spectroscopy, and electrochemical impedance spectroscopy. A multiphase layered structure is revealed, which is shown to remain relatively unchanged during extended cycling (up to 250 cycles at 1.5 mA·cm-2, 3 mA h·cm-2, 50 °C). The main components detected by MAS NMR and XPS after several hundreds of cycles are LiF and breakdown products from the bis(fluorosulfonyl)imide anion including Li2S. Similarities in chemical composition are observed in the case of the dilute (0.5 mol·kg-1 of Li salt in IL) and the highly concentrated (3.8 mol·kg-1 of Li salt in IL) electrolyte during cycling. The concentrated system is found to promote the formation of a thicker and more uniform SEI with larger amounts of reduced species from the anion. These SEI features are thought to facilitate more stable and efficient Li cycling and a reduced tendency for dendrite formation.
History
Journal
ACS applied materials and interfacesVolume
10Issue
7Pagination
6719 - 6729Publisher
American Chemical SocietyLocation
Washington, D.C.Publisher DOI
eISSN
1944-8252Language
engPublication classification
C1 Refereed article in a scholarly journalCopyright notice
2018, American Chemical SocietyUsage metrics
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No categories selectedKeywords
FSISEI layerX-ray photoelectron spectroscopyionic liquidslithiumScience & TechnologyTechnologyNanoscience & NanotechnologyMaterials Science, MultidisciplinaryScience & Technology - Other TopicsMaterials ScienceTRANSFORM INFRARED-SPECTROSCOPYSOLID-STATE NMRLI-7 MAS NMRXPS ANALYSISELECTROCHEMICAL PROPERTIESCHEMICAL-REACTIONFILM FORMATIONIMIDE ANIONBATTERIESSURFACE
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