Investigating Molecular Interactions through Computational Modeling, Thermodynamic Analysis, and Acoustic Measurements of LiOTf in Aqueous TEGDME and DME Solutions at Different Temperatures

This study investigates solute-solvent interactions in ternary systems consisting of lithium trifluoromethanesulfonate (LiOTf) as the solute and tetraethylene glycol dimethyl ether (TEGDME) and 1,2-dimethoxyethane (DME) as solvents over a range of temperatures (293.15-313.15 K). A multidisciplinary approach involving computational modeling, thermodynamic analysis, and acoustic measurements was used to elucidate molecular-level dynamics. The positive <i>V</i> _ϕ ⁰ values in the thermodynamic analysis revealed the prevalence of solute-solvent interactions in the investigated ternary (LiOTf + H₂O + DME/TEGDME) solutions. Hepler's constant was determined to predict the structure maker/breaker behavior. Cyclic voltammetry analysis showed that TEGDME offers a higher electrochemical window (EW) of 1.36 V in 0.01 TEGDME and 1.40 V in 0.05 TEGDME compared with that of 1.25 V in 0.01 DME and 1.38 V in 0.05 DME, yielding favorable and comparable working EWs. DFT calculations using the B3LYP functional and 6-311++G(d,p) basis set provided insights into the electron-donating and -accepting properties of the molecules, showing higher reactivity for LiOTf. These findings present novel insights into ternary electrolyte systems, which hold the potential for applications in energy storage technologies.