Direct electrochemical reduction of solid vanadium oxide to metal vanadium at low temperature in molten CaCl₂-NaCl

V₂O₅ sintered pellets and graphite rods were employed as the cathode and the anode, respectively; a molten CaCl₂-NaCl salt was used as the electrolyte. Then, V₂O₅ was directly reduced to metal vanadium by the Fray-Farthing-Chen (FFC) method at 873 K to realize low-temperature electrolysis. Two typical experimental conditions, electrolysis time and voltage, were taken into account to investigate the current efficiency and remaining oxygen content in electrolyzed products. The composition and microstructure of the products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). SEM observations show that a higher voltage (1.8-3.4 V) and a longer electrolysis time (2-5 h) can improve the product quality separately, that is, a lower remaining oxygen content and a more uniform microstructure. The products with an oxygen content of 0.205wt% are successfully obtained below 3.4 V for 10 h. However, the current efficiency is low, and further work is required.