The thermodynamic model for species distribution in aluminium chloride (AlCl3) and 1-butyl-3-
methylimidazolium chloride (BMIC) system was developed. The experimental thermodynamic data,
considering a range of aluminium chloride species, such as AlCl4-, Al2Cl7-, Al3Cl10-, Al4Cl13-, and Al2Cl6
were used in developing the model. When the XAlCl3 was in the range of 0 to 0.50, only anion species
Cl- and AlCl4- were existing in the solution. As the XAlCl3 value increased more than 0.50, the available
anions were Al2Cl7-, Al3Cl10-, Al4Cl13-, and Al2Cl6. Specifically, the concentration of Al2Cl7- increased
in the composition range from 0.50 to 0.67 XAlCl3, after which it decreased. This change in the
concentration of Al2Cl7- was due to its reaction with excess AlCl3, leading to the formation of Al3Cl10-.
The average cathode current density was determined by the electrochemical experiments varying
XAlCl3 from 0.50 to 0.71 in the AlCl3:BMIC solutions. The average cathode current density increased
as the XAlCl3 increased from 0.50 to 0.67. However, it decreased when the XAlCl3 > 0.67. This trend
can be attributed to the electroactive species Al2Cl7-. The Al2Cl7- promotes the reduction rate at the
cathode, resulting in an increase in the average cathode current density.