Effects of Rare-Earth Content on the Properties of Co-Free MmxMl1-x(NiCuAlZn5)Hydrogen Storage Alloys

MmxMl1-xNi4.14Cu0.5Al0.3Zn0.06 (Mm=Ce-rich misch-metal, Ml=La-rich misch-metal, x=0, 0.2, 0.4, 0.6, 0.8, 1) alloys have been synthesized by the inter-media alloy method. The properties of these alloys have been systematically investigated by means of X-ray diffraction (XRD), pressure-composition isotherms (PCT), electrochemical impendence (EIS) and cyclic voltammogram (CV). The X-ray diffraction results indicated that these alloys had a CaCu5-type hexagonal crystal structure. With increasing the Mm content, the plateau pressure and volume expansion of their hydrides were increased, but the volume of unit was decreased.