Low Temperature Electrodeposition of Titanium in Fluoride-Added LiCl–KCl–CsCl Molten Salt

Abstract

We investigated electroreduction of Ti²⁺ to metallic titanium in the LiCl–KCl–CsCl system, which has a eutectic point at 263 °C. Cyclic voltammetry was carried out in the TiCl₂-saturated LiCl–KCl–CsCl at 300 °C, and the effect of F⁻ addition on the reduction behavior of Ti²⁺ was investigated. It was revealed that addition of F⁻ increases the limiting current density of electrodeposition of titanium at 300–500 °C. This might be mainly attributed to the increase in total concentration of soluble titanium ions in the molten salt. Then, we demonstrated the electrodeposition of metallic titanium in the LiCl–KCl–CsCl with and without F⁻ at 350 °C. After the electrolysis in F⁻-added molten salt and acid leaching, LiF remained on the deposited titanium. This is because the solubility of LiF in aqueous solution is quite low. An efficient method to remove LiF is required when F⁻-added LiCl–KCl–CsCl is used as electrolyte.

Change of limiting current densities of electrodeposition of Ti with fluoride ion concentration, X_F, in LiCl–KCl–CsCl–KF molten salt in TiCl₂-saturated condition.