The Application of Low-Melting LiCl-KCl-CsCl Eutectic to Electrodeposit Uranium Metal

The aim of this work is to explore the electrodeposition of uranium in low-melting LiCl-KCl-CsCl eutectic. A variety of conventional electrochemical techniques, including cyclic voltammetry (CV), chronopotentiometry (CP), and chronoamperometry (CA), were employed to study the electrochemical and kinetic properties of uranium at different temperatures ranging from 573 to 872 K. First, the electrochemical behaviors and diffusion coefficients of uranium species in the melts were investigated and compared to the published results. The temperature significantly affects the cathodic current response of the U4+/U3+ couple within the low temperature range. Moreover, the nucleation mechanisms of uranium in the electrodeposition process were evaluated, and the results indicated that nucleation and growth tend to occur via the same instantaneous mode at all applied temperatures and overpotential ranges. Finally, metallic uranium was deposited by potentiostatic electrolysis at an overpotential of -100 mV vs. U3+/U at different temperatures, and their morphologies and compositions were characterized by SEM-EDS and XRD, respectively. The results show that from 573 to 773 K, uranium deposits evolve form one-dimensional needle-like to multidimensional dendritic structures. No dendrite-free uranium deposits were obtained in the CsCl-containing melts regardless of the temperature. (C) 2019 The Electrochemical Society.