Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster Session I

CPP 17.12: Poster

Montag, 1. April 2019, 17:30–19:30, Poster B1

Correlated ion motion in lithium bis(trifluoromethanesulfonyl)imide – glyme solvate ionic liquids: Atomistic insights from molecular dynamics simulations — •Andreas Thum¹, Diddo Diddens², and Andreas Heuer¹ — ¹Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany — ²Helmholtz-Institut Münster (IEK-12), Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany

Motional coupling of ions strongly influences the ionic conductivity of electrolyte solutions and ionic liquids (ILs). In both, the overall anticorrelated motion of like-charged ions reduces the conductivity compared to the ideal Nernst-Einstein conductivity. In electrolyte solutions, the overall correlated motion of opposite-charged ions lowers the conductivity, too. Contrary, in ILs this motional coupling is overall anticorrelated and enhances the conductivity.

To see how dynamic ion correlations evolve in time and space, we performed molecular dynamics simulations of mixtures of lithium bis(trifluoromethanesulfonyl)imide with glymes. These mixtures are known to form solvate ionic liquids (SILs) if mixed in a 1:1 molar ratio. The mixtures investigated here had molar ratios of 2:1, 3:2, 1:1, 1:2, 1:4 and 1:8, covering highly concentrated solutions, SILs and conventional solutions. We found that regarding the motional ion coupling the 2:1, 3:2, 1:1 and 1:2 mixtures behave like conventional ILs, whereas the 1:4 and 1:8 mixtures behave like conventional electrolyte solutions.