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

摘要

The electrochemical behavior of Te2- ions was investigated in the LiCl-Li2Te binary on glassy carbon electrodes at 650 degrees 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 x 10(5) cm(-2) 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.