Electrochemical Behaviors and Thermodynamic Properties of Ce on Liquid Bi, Sn, and Zn Electrodes in Molten LiCl-KCl Salt
Jun Woo Park, Han Lim, Jong-Il Yun
Abstract
This study presents the electrochemical behaviors and thermodynamic properties of Ce on liquid Bi, Sn, and Zn electrodes in molten LiCl-KCl eutectic salt. First, the Ce-metal binary systems on the solid tungsten electrode were investigated to determine the formation of Ce-metal intermetallic compounds during the electrowinning process. In these experiments, the formation of five Ce–Bi intermetallic compounds, eight Ce–Sn intermetallic compounds, and nine Ce–Zn intermetallic compounds was confirmed from the oxidation peaks of cyclic voltammetry. The standard Gibbs free energy of formation of each intermetallic compound was calculated from plateaus of the open-circuit chronopotentiometry. Subsequently, the electrochemical behaviors of Ce were investigated on liquid Bi, Sn, and Zn electrodes using cyclic voltammetry. In particular, while the reduction potentials of Li and Ce were too close to differentiate on the liquid Bi and Sn electrodes, they were not on the liquid Zn electrode. Peak potentials from cyclic voltammetry were utilized to calculate the activity coefficients of Ce in the liquid Bi, Sn, and Zn electrodes, which were 3.16 × 10 −14 , 1.82 × 10 −12 , and 9.05 × 10 −10 , respectively.