THE KINETICS OF THE SODIUM ELECTRODE-REACTION IN MOLTEN SODIUM-CHLORIDE

The kinetics of the sodium electrode reaction in molten sodium chlorid e has been investigated at several temperatures using electrochemical impedance spectroscopy (EIS) and the potential relaxation method (PRM) after galvanostatic perturbation. The electrode process exhibits a mi xed charge-transfer diffusion character since sodium ions in the melt exchange with sodium in the sodium-lead alloy used as a working electr ode. The standard rate constant and the activation energy of the charg e-transfer reaction as well as the diffusion impedance have been deter mined. The electrode is very reversible with an exchange current densi ty that varies from about 100 A cm(-2) at 820 degrees C to about 200 A cm(-2) at 920 degrees C. In such a reversible system a double-layer i nductance is observed.