Aluminum Ion Species Transport in Pure and Additive Modulated Deep Eutectic Solvents (DES) Electrolytes

The effect of additives on the aluminum species transports in varying molar ratios of AlCl3 deep eutectic solvents (DES) was studied using EIS conductivity measurements. The amides studied were acetamide, propionamide, and butyramide and the molar ratios ranged from 1:1 -1.7:1 for each AlCl3:amide DES. The additives studied were propylene carbonate (PC) and fluoroethylene carbonate (FEC) in 5wt%. While FEC generally lowered the conductivities, PC appears to shift the reaction equilibrium towards lower AlCl3 concentration. It is possible the fluorine atom on the FEC interacts with the [AlCl2(amide)n]+ species, creating stronger interactions that lowers the conductivity. The data displayed non-Arrhenius behavior and were fitted using the Vogel-Fulcher-Tammann equation to reveal dynamic behaviors similar to some pure ILs where the effective inter-conversion between the trans and cis conformations of the anion facilitated faster ion dynamics. These results can be helpful in modifying DES and similar aluminum solvents for electrolyte applications.