Zirconium, a critical rare metal with exceptional corrosion resistance and nuclear applications, is conventionally produced via the energy-intensive Kroll process. The electrolysis of ZrC_xO_y soluble anodes has been extensively investigated due to its advantages in having a short process flow and resulting in high-quality products. In particular, during the electrolysis of zirconium oxycarbide with a C:O molar ratio of 1:1, gaseous CO can be released, and no residual anodes are generated, which is extremely appealing. In this regard, this paper explores the feasibility of preparing zirconium metal through high-temperature vacuum reduction to produce zirconium oxycarbide using ZrO₂ as the raw material, followed by direct molten-salt electrolysis. Firstly, the reduction products were characterized using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The results showed that under a vacuum of <10 Pa at 1750 °C, the reduction products mainly consisted of ZrC_xO_y and a small amount of ZrO₂, and they exhibited good electrical conductivity (0.0169 Ω·cm). Subsequently, the cyclic voltammetry test results of the reduction products revealed the reversible redox behavior of ZrC_xO_y. There were characteristic oxidation peaks at −0.53 V and −0.01 V (vs. Pt), corresponding to the formation of Zr²⁺ and Zr⁴⁺, respectively, and a reduction peak at −1.51 V, indicating the conversion from Zr²⁺ to Zr. Finally, β-zirconium metal with a purity of 99.2 ± 0.3 wt.% was obtained through potentiostatic electrolysis, and its quality met the R60704 grade specified in ASTM B551-12 (2021). This study offers a novel approach for the short-flow preparation of zirconium metal, which is conducive to expanding its applications.

Liquid metal cathodes, particularly liquid cadmium (Cd), are widely used in molten salt electrorefining and pyrochemical reprocessing of spent nuclear fuel due to their high electrical conductivity, strong affinity for actinides, and favorable alloying characteristics. During electrorefining, reduced metal species enter the liquid Cd phase and may exist as dissolved atoms, liquid alloys, or intermetallic compounds, all of which significantly influence deposition behavior, separation selectivity, and cathode performance. Although numerous experimental and theoretical studies have investigated metal solubility, alloy formation, and diffusion in liquid Cd systems, the current understanding remains fragmented. Thermodynamic phase behavior and mass transport kinetics are often discussed separately, and reported diffusion data show considerable discrepancies owing to variations in experimental techniques and interpretations. In addition, the relationship between phase stability, diffusion mechanisms, and electrochemical conditions in practical electrorefining environments has not yet been systematically clarified. This review aims to present an integrated thermodynamic–kinetic perspective on the behavior of metals in liquid Cd cathodes. Recent progress in dissolution behavior, alloy phase formation, and diffusion-controlled transport processes is critically summarized. The differences in solubility and precipitation behavior of actinides, rare-earth elements, and selected transition metals are analyzed in relation to binary phase diagrams and thermodynamic stability. Furthermore, experimental methods for determining diffusion coefficients, including capillary techniques and electrochemical approaches, are comparatively evaluated. By correlating thermodynamic phase stability with diffusion-driven mass transport, this work provides a coherent framework for understanding metal behavior in liquid Cd cathodes and offers insights for optimizing molten salt electrorefining and advanced nuclear fuel cycle technologies.

The pyrometallurgical reprocessing of spent fuel developed by the United States is currently one of the most promising nuclear fuel reprocessing methods. The electroreduction, electrolytic refining, and electrodeposition processes involve electrochemical research in high-temperature molten chloride systems. In recent years, much progress has been made in simulating and studying molten-salt systems from a microscopic perspective using the first-principles molecular dynamics (FPMD) simulation technique. Using this method for simulation calculations is more conducive to analyzing the microscopic action mechanism and microscopic mechanism in the system from the atomic level and explaining the internal reasons for various electrochemical behaviors and phenomena. This opens up a new path for the study of molten-salt electrochemical systems. However, there are still a few systematic reviews of simulating work in first-principles computation. Therefore, this work summarizes the theoretical calculation work on molten-salt electrochemical systems of recent years, focusing on the research progress in computational aspects such as coordination properties, physical properties, and electrode behavior, which has good guiding value for the application of FPMD in molten-salt electrochemistry.