Rotating disk electrode study of a Ti3+/Ti electrode in LiCl-KCl eutectic and NaCl-MgCl2-KCl melt

The electrochemical behavior of Ti3+/Ti electrodes in alkali-chloride melts has been studied using the rotating disk electrode (RDE) technique. The st eady state polarization curves and results from the RDE analysis revealed t hat the cathodic reduction of the Ti3+/Ti electrode in LiCl-KCl eutectic co nsists of a two-step reduction in which the latter step, corresponding to t he reduction of Ti2+ to Ti, is accompanied by the following inverse-disprop ortionation reaction, 2Ti(3+) + Ti --> 3Ti(2+). Comparison of the cathodic behavior of the Ti3+/Ti electrode in LiCl-KCl eu t. with that in NaCl-MgCl2-KCl melt indicates that the lower valence Ti2+ i s Stable in the latter melt where high cathodic current results in a smooth deposit. The diffusion coefficients of Ti2+ in these melts were found to b e 4.6 x 10(-10) (LiCl-KCl eut.) and 1.7 x 10(-10) m(2) s(-1) (NaCl-MgCl2-KC l melt), respectively.