Molecular Insights into Solvation Behavior of Zinc Chloride-Based Deep Eutectic Solvent–Propylene Carbonate Electrolytes: A Combined Volumetric and Density Functional Theory Study

Zinc-based energy storage devices have garnered a lot of attention due to their low cost and high abundance. In this work, the solvation structure, transport properties, and electrochemical behavior of triethylmethylammonium tetrafluoroborate (TEMABF 4 ) solutions with concentrations ranging from 0.01 to 0.10 mol kg –1 in propylene carbonate (PC)-based electrolytes containing zinc chloride (ZnCl 2 )–ethylene glycol (EG) deep eutectic solvents, ZEDES (1:4) and ZEDES (1:6), at weight fractions of 0.1 and 0.2 were systematically investigated. A combination of volumetric measurements, density functional theory (DFT) calculations, and electrochemical analysis was employed to carry out this study. The addition of ZEDES to PC lowers the apparent and partial volume of pure PC, indicating strong electrostriction and compact solvation environments dominated by ion–polar interactions. Despite very high viscosity and low ionic conductivity of pure ZEDESs, their ensemble with PC resulted in a viscosity of 2–4 mPa s and specific conductance of up to 2.8 mS, highlighting the significant influence of solvent composition on the transport properties of the electrolytes.