Kinetics of aluminium deposition from aluminium chloride—alkali chloride melts

The kinetics of aluminium deposition from NaClAlCl3 and NaClKClAlCl3 melts (cAlCl3 < 0.4 mol%) was studied by linear sweep voltammetry and potential step amperometry. The reduction of AlCl3 on tungsten and aluminium electrodes was found to be diffusion controlled. The diffusion coefficients of AlCl3 were: 3.5 × 10−5 cm2 s−1 at 820°C in NaClAlCl3, 2.7 × 10−5cm2s−1 at 825°C, and 2.1 × 10−5cm2s−1 at 705°C in KClNaClAlCl3. The rate constant for AlCl3 reduction at these conditions was found to be in the order of 0.2 cm s−1, in good agreement with extrapolated literature data.