Investigating the physicochemical properties and interactions behavior of lithium perchlorate in ternary solutions of ethaline DES and bio-additives

Deep eutectic solvents (DES) are becoming popular in energy storage applications, especially as electrolytes because of their favorable properties like low toxicity, great biodegradability, high thermal stability, and availability. To design, optimize, and develop new lithium-ion battery electrolytes, it is important to understand the physicochemical properties and molecular interactions of these green solvents. In this respect, the density (ρ) and sound speed (u) at four distinct temperatures were measured and at different concentrations of lithium perchlorate (LiClO₄) solutions of the ethaline DESs along with dextrose and L-tyrosine as additives. In the whole concentration range, using density and speed of sound, physical parameters like apparent and partial molar volumes ( \({V}_{\varnothing }\) $V_{\varnothing }$ and \({V}_{\varnothing }^{0}\) $V_{\varnothing }^0$ ), apparent and partial molar isentropic compressions ( \({K}_{\varnothing ,S}\) $K_{\varnothing ,S}$ and \({K}_{\varnothing ,S}^{0}\) $K_{\varnothing ,S}^0$ ), and limiting molar expansibilities \(\left({\phi }_{E}^{0}\right)\) $\left({\varphi }_E^0\right)$ were calculated and results indicate that solvent-solvent interactions are dominant over solute-solute interactions with the rise in temperature and potentially enhancing ion solvation. Also, Hepler’s constant and other metrics demonstrate the structure breaker behavior of the studied systems. Cyclic voltammetry (CV) studies were also conducted to predict the electrochemical working stability of the studied systems. FTIR studies were also done to further analyze the interactions.