Understanding the bulk and interfacial structures of ternary and binary deep eutectic solvents with a constant...

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Deep eutectic solvents (DESs) are emerging as advanced electrolytes for supercapacitors and batteries.
• Their unique properties include wide electrochemical windows, low viscosity, and high ionic conductivity.
• However, a deep understanding of their molecular structural behavior is lacking.

Purpose of the Study:

• To investigate the bulk and interfacial molecular structures of two DES electrolytes.
• To elucidate the role of molecular structure in DES efficiency for energy storage applications.

Main Methods:

• Molecular dynamics simulations were employed to study binary (choline chloride:urea) and ternary (choline chloride:urea:ethylene glycol) DESs.
• Analysis included radial distribution functions (RDFs), mean square displacement (MSD), self-diffusion coefficients, and interfacial properties near graphene electrodes.

Main Results:

• Neutral species, alongside hydrogen bonding and correlations, significantly influence the bulk properties of DESs.
• Multilayers of neutral species were observed near electrodes, in addition to ionic components.
• Differential capacitance (Cd) was higher at the positive electrode, and the ternary DES exhibited greater total capacitance than the binary DES.

Conclusions:

• The study provides molecular-level insights into DES behavior, highlighting the crucial role of neutral species.
• Findings offer a better perspective for designing next-generation electrolytes for electric double-layer capacitors.