Formation of LaNi5 Hydrogen Storage Alloy by Electrodeposition of La Using Molten Salt

Abstract

A hydrogen storage alloy was formed by electrodepositing La using a molten salt. La was electrodeposited using Ni as a substrate in NaCl-KCl-5.0 mol% LaF3 molten salt at electrodeposition temperatures of 750 °C and 900 °C. The electrodeposition potential was −2.25 V. The LaNi5 hydrogen storage alloy was then prepared by the electrodeposition of La and the mutual diffusion of the Ni substrate. As a result, it was clarified that La can be electrodeposited by using a molten salt. Single-phase LaNi5 was produced at 750 °C rather than at 900 °C. It became possible to uniformly form LaNi5, an intermetallic compound, on the substrate surface. The prepared hydrogen storage alloy was exposed to Ar-10%H2 to store hydrogen; at this time, hydrogen was stored by changing the sample temperature. The discharged hydrogen was measured by a gas sensor. It was clarified that the hydrogen storage and hydrogen discharge were the highest in the sample obtained by electrodepositing La for 1 h at 750 °C. LaNi5 formed by electrodeposition showed hydrogen storage properties, and this method was found to be effective even for samples with complex shapes.