Effect of Biocompatible Deep Eutectic Solvent on the Solvation Behavior of the Thermodynamic Properties of Lithium Perchlorate in Propylene Carbonate: Experimental and Theoretical Study

Using organic solvents in lithium-ion battery electrolytes presents environmental issues due to their volatility and toxicity. This work explores lithium perchlorate in deep eutectic solvents (DESs) as eco-friendly alternatives for organic electrolytes in batteries and electrochemical devices. We studied ternary mixtures of lithium perchlorate with DESs (using choline chloride (ChCl) as the hydrogen bond acceptor and ethylene glycol (EG) in a 1:2 molar ratio, malonic acid (MA) in a 1:1 molar ratio, lactic acid (LA) in a 1:2 molar ratio, or propionic acid (PA) in a 1:2 molar ratio as hydrogen bond donors) and propylene carbonate. Experimental measurements of density, speed of sound, and viscosity were conducted at temperatures from 288.15 to 318.15 K. These data facilitated the calculation of thermophysical properties such as the viscosity B-coefficient, partial molar volumes of transfer (ΔtrVφ0), standard partial molar volume (Vφ0), apparent molar volume (Vφ), partial molar isentropic compressibility (κφ0), and apparent molar isentropic compressibility (κφ). Additionally, density functional theory (DFT) calculations were performed using Gaussian09. The experimental data showed that the interactions between lithium perchlorate and ChCl/lactic acid were stronger than those with other studied DESs.