In this article, electrical conductivity of aluminum chloride (AlCl₃) and 1-butyl-3-methylimidazolium chloride (BMIC) ionic liquid electrolytes was reported as a function of temperature and AlCl₃ mole fraction. Electrical conductivity increases when the mole fraction of AlCl₃ is between 0 and 0.50 and decreases when the concentration of AlCl₃ exceeds 0.50. An anionic species distribution profile was developed to correlate electrical conductivity, and it was found that AlCl4− anion mainly influences the electrical conductivity of AlCl₃:BMIC electrolytes.

Abstract

Electrical conductivity (σ) of aluminum chloride (AlCl₃) and 1-butyl-3-methylimidazolium chloride (BMIC) ionic liquid (IL) was investigated as a function of temperature and AlCl₃ mole fraction ( XAlCl3). Electrochemical impedance spectroscopy was used to measure the electrical conductivity. Composition of AlCl₃:BMIC ionic liquid was varied by changing the XAlCl3 from 0 to 0.67. The temperature was changed from 70°C to 110°C at 10°C intervals. It was found that the electrical conductivity increases with an increase in temperature. Electrical conductivity increases with XAlCl3 from 0 to 0.5 and then starts to decrease after XAlCl3 = 0.5. A species concentration profile was developed based on thermodynamic model at room temperature for the IL containing BMI+, Cl−, AlCl4−, Al2Cl7−, Al3Cl10−, Al4Cl13−, and Al2Cl6 at different XAlCl3. The only anion species presents between 0 and 0.5 XAlCl3 are Cl− and AlCl4−. Anions like Al2Cl7−, Al3Cl10−, Al4Cl13−, and Al2Cl6 are found at higher XAlCl3. A good agreement between the model and the experimental data was obtained. The variations in anion concentration, molecular structure, and cation–anion interactions are to be the causes of the changes in electrical conductivity of AlCl₃:BMIC system.