Composition Gradients in Molten Salt Binary Mixtures during Electrolysis at High Current Density

Abstract

Separation of components has been measured in binary molten salt mixtures, , subjected to electrolysis between silver electrodes. The analysis of thin slices of frozen mixture contained in silica frits gives qualitatively the composition changes between anode and cathode and shows the expected enrichment of potassium ions at the cathode. Changes in concentration at the electrodes are measured electrochemically in free electrolytes and in electrolytes contained in frits. The time dependence of concentration at the electrodes is obtained both during electrolysis and during relaxation following electrolyses of different durations. The experimental results confirm the predictions from a mass transport model proposed previously for systems analogous to mixed molten salt batteries operated at high current densities.