Electrochemical behavior and electrolysis of VCl3 in molten LiCl-KCl eutectic salts on tungsten electrode

This paper investigated the electrochemical behavior of V(III) on W electrode using cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit chronopotentiometry (OCP) at 773 K in LiCl-KCl molten melt. The results indicated that the reduction process of V ions in LiCl-KCl molten salt was a two-step reaction: V(III)-> V(II)-> V(0). The diffusion coefficient of V ions was determined through cyclic voltammetry, square wave voltammetry, and convolution voltammetry, with all values found to be on the order of 10-5 cm2 s- 1. The standard rate constant k0 and the transfer coefficient alpha were also evaluated using convolutional voltammetry. Thermodynamic properties, including the Gibbs free energy of formation, standard enthalpy, and entropy of VCl2, were calculated using open-circuit chronopotentiometry over the temperature range of 693-813 K. Electrodeposition was performed at - 2.30 V, - 2.70 V, - 2.90 V, and - 3.10 V vs. Cl2/Cl- on the W electrode by two- or threeelectrode system and the resulting cathodic products were characterized using XRD and SEM-EDS. The main component of the deposition product was metallic vanadium. As the applied potential shifted negatively, the vanadium extraction efficiency increased. The highest extraction efficiency was more than 99.50 %, with a current efficiency of 86.37 % under the two-electrode system.