A Substituted Imidazolium Chloroaluminate Molten Salt Possessing an Increased Electrochemical Window

The preparation and characterization of a new molten salt system prepared from aluminum chloride and a trialkylimidazolium halide is described, particularly those molten salts prepared with 1,2‐dimethyl‐3‐propylimidazolium chloride. Molten salts prepared with this salt are liquid over the composition range of ca. 0.65:1 to 2.2:1 AlCl 3 : DMPrICl at 25°C. A value for the acid‐base equilibrium constant of ( 2.0 ± 0.5 ) × 10 − 15 was determined by potentiometric titration. Cyclic voltammetry results are presented comparing reduction potentials for MEICl and DMPrICl and the electrochemical windows of the respective molten salts. For a 1:1 AlCl 3 : DMPrICl molten salt, an electrochemical window of nearly 5V is obtained at glassy carbon.