Electrochemical Behavior of Telluride Ions (Te2–) in Molten LiCl–Li2Te Solution at 650 °C

The electrochemical behavior of Te2– ions was investigated in the LiCl–Li2Te binary on glassy carbon electrodes at 650 °C as a means to understand the fundamental thermodynamic and mass transport properties of Te2– ions. Cyclic voltammetry and constant-potential electrolysis confirmed an electrochemically reversible, two-electron soluble–insoluble reaction of Te2–/Te­(l). The formal potential for the Te2–/Te­(l) reaction was determined to be 1.744 V vs Li+/Li­(l), and the diffusivity of Te2– ions was about 0.44–1.25 × 10–5 cm2 s–1. The low value for diffusivity relative to those of other cations in molten salts suggests the possibility of forming complex ions such as [Li8Te]6+ due to strong chemical interactions with Li+ ions in the electrolyte. The anodic polarization of Te­(l) indicated that the formation of TeCl2(g) and the cathodic polarization of Te­(l) involved the codeposition of Li metal into the Te­(l). The results of this work provide essential knowledge in developing electrochemical processes for separation of tellurium as well as in mitigating the degradation reactions with structural materials.