Effect of fluoride addition on electrochemical behaviors of V(III) in molten LiCl-KCl
(1. Henan Province Industrial Technology Research Institute of Resources and Materials, Zhengzhou University, Zhengzhou 450001, China;
2. National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China)
2. National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China)
Abstract: X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to analyze the complexes in LiCl-KCl eutectic salt containing VCl3 and KF. The additional fluoride ions would replace chloride ions and combine with V(III) to form VF63-. The electrochemical behavior of V(III) was evaluated under condition of the molar concentration ratio of F- to Vn+ (α) equal to 0:1, 1:1, 2:1, 5:1, 20:1 and 50:1, respectively. The results showed that a new reduction step appeared: VF63-→V2+, and the reduction mechanism of vanadium ions became more complicated. The metallic vanadium was deposited on the tungsten electrode at -2.90 V in the LiCl-KCl melts for 6 h, and the products were characterized by SEM-EDS. It was indicated that the particle size of the product decreased with adding fluoride ions for the forming of the coordination compound VF63-.
Key words: V(III) ion; molten salt; electrochemical behavior; reduction mechanism; complex