Dynamic evolution of high-temperature molten salt electrolysis of titanium under different operational conditions

Although the solid-state electrolysis process is a widely effective method for titanium scrap upcycling and high-purity titanium preparation, it is difficult to optimize the electrolysis process and improve the electrolysis efficiency due to harsh reaction conditions. In order to further improve the current efficiency and understand the internal mechanism of the electrolysis process, we employed in situ X-ray computer microtomography to study the electrolysis process under different conditions. The results showed that, at the same current density, the dissolution efficiency of the Ti anode and the thickness of the cathodic coating under pulse electrolysis were better than those in direct-current (DC) electrolysis, especially the deposition effect was more obvious at the bottom of the cathode. To reveal this evolution mechanism, we carried out numerical simulation to track the variation of titanium ion concentration at the local interface of the electrode and found that the titanium ions had a higher concentration on the cathode surface during the pulse electrolysis process than that during the DC electrolysis process. Moreover, we performed pulse electrolysis at different current densities and demonstrated that the current efficiency of pulse electrolysis increases with the decrease of current density within a current density range (0.1-0.4 A cm⁻²). X-ray computer microtomography was used to visualize the electrorefining process of titanium, which provides a direct insight into the internal dynamics of titanium electrolysis and will be helpful in improving the electrolysis efficiency in industry.