Comprehensive electrochemical insights and kinetic analysis of La(III) in LiF–CaF2 melt for efficient synthesis of LaNi5 alloy

A method for the preparation of LaNi 5 alloy by molten salt co-reduction is reported. The electrochemical co-reduction process of La(III) and Ni(II) as well as the reaction process of intermetallic compounds formation were investigated. It was confirmed that the diffusion coefficient of La(III) in LiF–CaF 2 molten salt is 4.684–8.098 × 10 −5  cm 2  s −1 at temperatures of 1113–1183 K. And the reaction activation energy was obtained to be 78.86 kJ mol −1 . And, the exchange current densities of La(III)/La(0) were determined by the Tafel (0.149–0.251 A cm −2 ) and linear polarization (0.143–0.204 A cm −2 ) methods. Furthermore, five different La–Ni intermetallic compounds were detected by studying the co-reduction reaction of La(III) and Ni(II) ions. Meanwhile, the formation potentials of La–Ni intermetallic compounds were defined by various electrochemical tests. In addition, the LaNi 5 alloy was obtained via potentiostatic electrolysis according to the electrochemical results. This study provides new insights into the electrochemistry of the LiF–CaF 2 –LaF 3 –NiF 2 molten salt and enhances the understanding of the molten salt electrolytic preparation of La–Ni alloys from co-reduction.