Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 47: Charged Soft Matter

CPP 47.6: Talk

Friday, March 15, 2013, 11:00–11:15, H34

Understanding microscopic processes in ionic liquids via MD-simulations — •Volker Lesch and Andreas Heuer — Westfälische Wilhelms-Universität Münster, Münster, Germany

Ionic liquids are promising candidates for electrolyte applications. One disadvantage is the slow lithium diffusion so improvements related to this property would be very useful. To investigate such transport processes, we employ MD-simulations as a powerful tool for a microscopic analysis.

Here we compare the properties of bis(fluorosulfonyl)imide (FSI) and bis(trifluoromethylsulfonyl)imide (TFSI). Although both anions are quite similar their properties are surprisingly different. More specifically, our research consists out of two parts. First, we study systems with the same counterion for lithium and EMIM. Many research groups only work on these systems because they cover different voltage ranges. In our investigations we focus on dynamical and structural properties. As one would expect the dynamics of the system which contains TFSI is much slower. This is related to stronger bonds between TFSI and lithium ions and an enhanced viscosity due to the sterical demands of TFSI. Second, we analyzed systems with mixed anions (ratio 1:0.29). These systems combine the properties of the two anions but unfortunately the electrochemical stability window decreases. Especially, the effects of FSI on TFSI and vice versa are of particular interest. Increasing the amount of TFSI leads to a faster dynamic for TFSI and slower dynamics for FSI. This contrasts to the results for the systems with the same counterion for both cations.