Effects of spinning rate on structures and electrochemical hydrogen storage performances of RE–Mg–Ni–Mn-based AB2-type alloys

Abstract

La was partially substituted by Ce with the aim of improving the electrochemical hydrogen storage performances of La1–xCexMgNi3.5Mn0.5 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys, and melt spinning technology was adopted to fabricate the alloys. The identification of XRD and SEM reveals that the experimental alloys consist of a major phase LaMgNi4 and a secondary phase LaNi5. The growth of spinning rate results in that the lattice constants and cell volume increase and the grains are markedly refined. The electrochemical measurement shows that the as-cast and spun alloys can obtain the maximum discharge capacities just at the first cycle without any activation needed. With the increase of spinning rate, the discharge capacities of the alloys first increase and then decline, whereas their cycle stabilities always grow. Moreover, the electrochemical kinetic performances of the alloys first increase and then decrease with spinning rate growing.