Erlangen 2022 – wissenschaftliches Programm

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AKE: Arbeitskreis Energie

AKE 3: Technologies for Defossilization

AKE 3.3: Vortrag

Mittwoch, 16. März 2022, 14:45–15:00, AKE-H16

Broadband dielectric spectroscopy on lithium-salt-based and choline-chloride-based DESs — •Arthur Schulz, Peter Lunkenheimer, and Alois Loidl — University Augsburg, Experimental Physics V, Augsburg, Bavaria

We have performed broadband dielectric spectroscopy (BDS) on three Lithium-salt-based deep eutectic solvents (DESs) - systems where the only cation is Li+ - covering a broad temperature and frequency range that extends from the low-viscosity liquid around room temperature down to the glassy state approaching the glass-transition temperature. We observe a relaxational process that can be ascribed to dipolar reorientational dynamics and exhibits the clear signatures of glassy freezing. We find that the temperature dependence of the ionic dc conductivity and its room-temperature value also are governed by the glassy dynamics of these systems, depending, e.g., on the glass-transition temperature and fragility. Compared to previously investigated systems, containing the same hydrogen-bond donors and choline chloride instead of a lithium salt, both the reorientational and ionic dynamics are significantly reduced due to variations of the glass-transition temperature and the higher ionic potential of the lithium ions. Additionally, we analyzed a range of deep eutectic systems composed of choline chloride and a carboxylic acid (e.g., maline, for which a relatively high room-temperature conductivity was reported) using BDS. The nature of the observed dynamic processes, as well as the evidence for and strength of their coupling are compared to previously investigated choline-chloride-based DESs.