Ionic conductivity of deep eutectic solvents: The role of orientational dynamics and glassy freezing

TL;DR

This study investigates how the reorientational dynamics and glassy freezing influence ionic conductivity in deep eutectic solvents, revealing a close coupling between dipolar motions and charge transport across a wide temperature range.

Contribution

It provides the first comprehensive analysis of the relationship between orientational dynamics and ionic conductivity in deep eutectic solvents using broadband dielectric spectroscopy.

Findings

Glassy freezing significantly affects ionic charge transport.

Ionic conductivity is closely coupled with reorientational dipolar motions.

The study spans from low-viscosity liquids to deeply supercooled states.

Abstract

We have performed a thorough examination of the reorientational relaxation dynamics and the ionic charge transport of three typical deep eutectic solvents, ethaline, glyceline and reline by broadband dielectric spectroscopy. Our experiments cover a broad temperature range from the low-viscosity liquid down to the deeply supercooled state, allowing to investigate the significant influence of glassy freezing on the ionic charge transport in these systems. In addition, we provide evidence for a close coupling of the ionic conductivity in these materials to reorientational dipolar motions which should be considered when searching for deep eutectic solvents optimized for electrochemical applications.