STUDY ON DEPOSITION POTENTIALS OF LITHIUM AND SODIUM-IONS AND DEPOLARIZATION IN BINARY CHLORIDE

Deposition potentials of Lithium and Sodium ions have been measured in binary chloride systems (LiCl-KCl, NaCl-KCl) by I-V curve method, to provide a theoretical base for preparing high purity Al-Li alloy by electrolysis in molten salt. The changes of free energy and enthalpy were calculated in terms of depolarization values on Al cathode. Thermodynamic meaning of depolarization was discussed in details and the empirical relation between binary alloy type and depolarization type was proposed. It is shown for the first time that the presence of a third element in Al-Li alloy can strengthen depolarization of Li ion at Al alloy cathode and give foundation for preparing high purity Al-Li-M ternary alloy. The effect of LiCl concentration on deposition potentials of Li ion at Al cathode in KCl-LiCl melt was studied and average active coefficient of LiCl was obtained.