Impedance Phenomena in Molten Salts

Impedances have been measured of polarized platinum micro‐electrodes in the molten salt systems, LiCl ‐ KCl at 400°C, NaNO 3 ‐ KNO 3 at 270°C, NaBr ‐ AlBr 3 at 225°C, and PbCl 2 at 530°C. Frequency dispersion of both the observed resistance and capacitance was evident in all cases, but apparent double layer capacities obtained by extrapolation to infinite frequency are in reasonable accord with some previously reported data. They are of magnitudes consistent with a simple Helmholtz model although the anodic values tend to be high, perhaps because of specific adsorption. Some measurements of faradaic impedance have also been made, but these were less successful and the exchange current for the Pt/Pt 2+ system is high.