Electrochemical Behaviors of Selenide and Telluride Ions in LiCl-KCl Eutectic Melts

• Published in: Journal of the Electrochemical Society 2020-05, Vol.167 (8), p.82511
• Main Authors: Sakamura, Yoshiharu, Murakami, Tsuyoshi, Uozumi, Koichi
• Format: Article
• Language: English
• Subjects: Copper selenide; Copper telluride; Electrodeposition; LiCl-KCl; Molten Salts - High Temperature Molten Salts; Selenium; Tellurium
• ISSN: 0013-4651; 1945-7111; 1945-7111
• DOI: 10.1149/1945-7111/ab904e

The redox behaviors of Se and Te in LiCl-KCl eutectic melts at 723 K were investigated. Liquid Se metal was cathodically dissolved in the form of Se2− ions. Cyclic voltammograms on a glassy carbon electrode indicated that the deposition of Se on the anode proceeded in two steps: Se2− was oxidized to Se22−, which was then oxidized to Se metal. When active metals such as Cu and Ni were used as the anode, their selenides were deposited at potentials more negative than that of Se22− formation. The deposition of Te proceeded in two steps similarly to Se. The redox potentials indicated that Te2− was more easily oxidized to the metallic form than Se2−. Various Cu compounds (Cu2Se, Cu2Te, Cu7Te4, and KCu3Te2) were identified on the Cu electrode in electrodeposition tests. Moreover, the effect of coexisting O2− ions was examined, and it was demonstrated that Se and Te were deposited on the Cu anode without Cu2O formation. Chemical extraction using Cu2O as a reactant was examined as an alternative to electrodeposition. Cu2O powder rapidly reacted with Se2− ions in the melt and Cu2Se was precipitated.