Hydrogen Storage Performances of Mg20Ni10-XMX (M=Cu, Co, Mn; X=0–4) Alloys Prepared by Melt Spinning

Abstract

In order to improve the glass-forming ability of the Mg2Ni-based alloy, we combine element substitution that is partially replacing Mg with La and Ni with M (M=Cu, Co, Mn) with melt spinning technology, successfully prepared the Mg2Ni-type Mg20-xLaxNi10 (x=0, 2, 4, 6) and Mg20Ni10-xMx (M=Cu, Co, Mn; x=0, 1, 2, 3, 4) hydrogen storage alloys with nano-crystalline and amorphous structure. The microstructures of the as-spun alloys are characterized by XRD and HRTEM and its gaseous and electrochemical hydrogen storage kinetics are also tested. The results show that when x≤2, the substitution of La for Mg has not changed its main phase Mg2Ni except for the appearance of a small amount of LaMg3 and La2Mg17 phase but when the substitute amount of La is x≥4, the major phase of the alloy is turned into LaNi5 and LaMg3. The replacement of La for Mg can not only improve the glass-forming ability of the Mg2Ni-type alloy significantly but also enhance its hydrogen absorption/desorption kinetics and electrochemical hydrogen storage properties dramatically. Likewise, the substitution of M (M=Cu, Co, Mn) for Ni can not alter the Mg2Ni major phase but the M (M=Co, Mn) substitute makes the amorphous forming ability increase. Moreover, the replacement of M (M=Cu, Co, Mn) for Ni greatly raises the gaseous hydrogen absorption/desorption kinetics and electrochemical hydrogen storage performances of the alloy. The melt spinning plays an obvious impact on the gaseous and electrochemical hydrogen storage properties of the alloy, that is to say, the gaseous hydrogen absorption/desorption kinetics of the alloy together with its electrochemical hydrogen storage ability increases with the spinning rate rising.