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This study demonstrates the pulsed-potential electrodeposition of reduced Zr species (ZrCl and Zr) in a molten LiCl–KCl salt. We report, for the first time, a new reduction reaction of Zr species (−1.90 V vs. Ag/AgCl 10 wt%) in molten LiCl–KCl salt, characterized by cyclic-voltammetry experiments using W and Zr electrodes. The pulsed-potential electrodeposition experiments were performed using an inert W-foil electrode in a molten ZrCl4–LiCl–KCl salt. Three cathodic-pulse potentials (−1.30, −1.60, and −1.90 V) were applied, and the chemical and structural characteristics of respective deposits were compared. The deposits were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and Raman spectroscopy. Additionally, we accomplished the pulsed-potential electrodeposition (>103 A/m2) of α-Zr metal with a practical ZrCl4 concentration (2.6 wt%). The results confirm that pulsed-potential electrodeposition can be employed for the selective deposition of the α-Zr metal by minimizing the co-production of ZrCl in molten LiCl–KCl salt while achieving excellent adhesion to the inert W electrode.

In the present work, a real-time monitoring system for molten LiCl-KCl eutectic salt medium is set up with optically accessible quartz windows mounted on the furnace and the CMOS camera. Based on the designed system, the real-time monitoring was carried out to investigate the electrode behavior in various electrochemical systems, such as (1) differences in Co morphology deposited in molten CoCl2-LiCl-KCl system by various electrochemical deposition methods, (2) a reoxidation behavior of electrochemically reduced lithium, and (3) a reduction of Zr(IV) ions to Zr(III) ions in the molten ZrCl4-LiCl-KCl system. By delivering the video signal from the CMOS camera to the PC which controls the potentiostat, the visual changes can also be synced with the measured current or potential during the experiment. This enables us to compare the visualized morphological properties on the surface of the working electrode under different applied potential conditions during the application of electroanalytical methods.

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