The electrochemical reduction of Pb(II), Zn(II) and Mg(II) ions at glassy C and W electrodes in a molten KCl–LiCl eutectic was studied by means of linear sweep voltammetry, convolutive potential sweep voltammetry, chronopotentiometry and chronoamperometry. In the case of Pb deposition, the initial nucleation stage was found to affect the shape of the voltammetric current peak. Convolutive potential sweep voltammetry was thus believed to be a more reliable method, than linear sweep voltammetry, for the calculation of the diffusion coefficient of the Pb(II) ion. No similar complications were observed for Zn and Mg because the nucleation over-potentials for these metals were significantly lower than that for Pb. On the other hand, Li co-deposition made it difficult to interpret Zn and Mg convolution voltammograms. Chronopotentiometry yielded essentially identical results for D[Pb(II)] as did voltammetric techniques. Due to a substantial residual current, the Sand equation was not obeyed by Zn(II) and Mg(II) ions. Determination of the diffusion coefficients from single potentiostatic current transients, and the Cottrell equation, was not found to be a very reliable method. Empirical expressions for the temperature dependence of diffusivity at 400 to 500C were calculated for all 3 ions.

Determination of Diffusion Coefficients of Depositing Ions in Molten Chlorides by Transient Electrochemical Techniques. T.Støre, G.M.Haarberg, R.Tunold: Journal of Applied Electrochemistry, 2000, 30[12], 1351-60