Effects of Current Density on Current Efficiency in Low Temperature Electrolysis with Vertical Electrode Structure

In this paper, ceramic based inert anodes and TiB2-C composite cathodes were used for electrolysis tests in KF-NaF-AlF3 based low-temperature electrolyte with vertical oriented electrodes, and the effects of current density on current efficiency and cathode performance were studied. The results showed that current efficiency could be significantly improved by increasing current density, but when the current density was increased to a certain value, the current efficiency would significantly reduce. When the current density of cathode projection plane was in the range of 0.27–0.47 A/cm2, current efficiency could be reached more than 90%. When it was higher than 0.54 A/cm2, current efficiency was reduced significantly and unstable. And when it was over 0.65 A/cm2, cathodes were easy to crack or crust. Under the condition of high current density, the increase of aluminum loss was the main reason leading to the decrease and instability of current efficiency.