Some Approaches to Novel Molten Salt Electrochemical Processes

This review article describes some selected novel molten salt electrochemical processes which have been challenged by the author and his co-workers. Metallic Na is produced with high current efficiency by the electrolysis of molten NaCl-ZnCl2 or NaOH using β-alumina diaphragm. Two kinds of chlorine recovery from HCl gas are possible by electrochemical processes in molten LiCl-KCl. A novel SiH4 production method has been proposed by the use of Si electrode in a molten LiCl-KCl-LiH system. N2 gas is cathodically reduced to form N3− ion in molten LiCl-KCl, which encourages the author to develop new applications, e.g., Li-N2 thermally regenerative fuel cell and thermogalvanic cell. Electrochemical implantation of nitrogen to form various metal nitrides is possible by the use of anodic reaction of N3− ion in a molten LiCl-KCl-Li3N system. Electrochemical implantation and displantation can be applied to form transition metal-rare earth alloys in molten LiCl-KCl containing rare earth chloride. Finally, as non-conventional electrochemical reactions, discharge electrolysis to form fine metal or carbon particles and electrochemical plantation of Zr on ceramics are introduced.