Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Dynamics of Molecules on Surfaces
O 5.3: Vortrag
Montag, 7. März 2016, 11:00–11:15, S053
Interaction of a Self-assembled Ionic Liquid Adlayer with Graphite(0001) and Reaction with Coadsorbed Lithium — •Florian Buchner1, Katrin Forster-Tonigold1, Maral Bozorgchenani2, Axel Gross1,3, and R. Jürgen Behm1,2 — 1Helmholtz Institute Ulm (HIU) Electrochemical Energy Storage, D-89081 Ulm, Germany — 2Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany — 3Ulm University, Institute of Theoretical Chemistry, D-89069 Ulm, Germany
The ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoro-methylsulfonyl)imide [BMP][TFSA] is a promising solvent/electrolyte for Li-ion batteries. In this model study we investigated the interaction of (sub-)monolayers of [BMP][TFSA] with a frequently used anode material as graphite(0001) under ultrahigh vacuum (UHV) conditions. Scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and dispersion corrected density functional theory (DFT-D) calculations were employed. After vapor deposition at 300 K and subsequent cool-down to 100 K the STM measurements reveal an ordered (2D) crystalline phase. The row-like adsorption structure is determined by anions and cations which are alternatingly aligned. DFT-D calculations predict that adsorbate-substrate interactions are dispersion interactions, and adsorbate-adsorbate interactions between the ion pairs are equally composed of electrostatic and dispersion interactions. In addition, to mimic an electrolyte, Li was stepwise post-deposited. Subsequent XPS measurements reveal decomposition products of [BMP][TFSA] like LiF, Li2S, and LiN3.