Formation of hydrogen absorption film by electrodeposition in molten salts

Hydrogen absorption alloy films have been produced by molten salt electrolysis. Lanthanum-Nickel alloy film can be formed on a nickel substrate in KCl-NaCl-LaCl3 molten salts by electrolysis-diffusion process. LaNi5 alloy was formed by mutual diffusion between La and Ni after La deposition on Ni substrate. Though several kinds of La-Ni compound existed in deposits, the alloy compounds on Ni substrate changed by electrolysis condition. According to the open-circuit potential measurement in molten salts after La electrodeposition, the formed compounds had a relation to the potential. In the case of the substrate electroplated a cobalt thin film on nickel, LaNi4.5Co0.5 was formed by the electrolysis in the molten salts with lanthanum ions. This ternary alloy film showed better hydrogen absorption behavior in cyclic charge/discharge test in alkaline solution.