Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Inorganic/Organic Interfaces

O 41.4: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster B

On the adsorption behavior of the ionic liquid [BMP][TFSA] on TiO₂ (110), Cu(111) and Ag(111) and the interaction with Li — •Maral Hekmatfar^1,2, Benedikt Uhl^{1, 2}, Florian Buchner^{1, 2}, Dorothea Alwast^{1, 2}, and R. Jürgen Behm^{1, 2} — ¹Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany — ²Helmholtz-Institute Ulm (HIU) Electrochemical Energy Storage, D-89069 Ulm, Germany

The ionic liquid n-butyl-n-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide [BMP][TFSA] is particularly interesting for the application in electrolytes for Li-ion batteries. In this model study we aim at a detailed understanding of the electrode|electrolyte interface at the molecular scale. In a first step [BMP][TFSA] was vapor deposited on Cu(111), Ag(111) and TiO₂(110) under ultra-high vacuum conditions. At 80 K [BMP][TFSA] adsorbs intact on all surfaces which was verified by XPS measurements; different molecular arrangements were observed by STM, which will be discussed. Upon co-deposition of Li to mimic electrolyte, decomposition of mainly the anion into, e.g., LiF and Li₂S was found on Cu(111) even at 80 K, while on Ag(111) and TiO₂ the IL is little or nearly not affected. Interestingly, on TiO₂(110) a new Ti³⁺ species is observed in the Ti 2p region, which points toward the reaction of Li with the surface. In contrast, on Cu(111) we assume that a surface mediated decomposition of [BMP][TFSA] with Li takes place. As the electrode|electrolyte interface strongly determines the functionality of a battery, we believe that our model study gives very new insights.