Electrochemical Performances and Microstructure of the Melt-Spun La-Mg-Ni System Hydrogen Storage Alloys

Abstract:

La-Mg-Ni system (PuNi3-type) La0.7Mg0.3Ni2.55-xCo0.45Cux (x=0, 0.2, 0.4) hydrogen storage electrode alloys were prepared by casting and melt spinning process. The microstructure and electrochemical performances of the as-cast and melten spun alloys were analyzed and measured. The effects of substituting Ni with Cu and melt spinning on microstructures and electrochemical performances of the as-cast and melten spun alloys were investigated in detail. The obtained results show that the as-cast and melten spun alloys are composed of the (La, Mg)Ni3 phase and the LaNi5 phase as well as the LaNi2 phase. The melt spinning have an inappreciable influence on the phase compositions of the alloys, but leads to the homogeneity of the diffraction peaks of the alloys. The results obtained by the electrochemical measurement indicate that the substitution decreased the discharge capacities of the as-cast and melt spun alloys, whereas improved the cycle stability and discharge voltage characteristic of the as-cast and melten spun alloys. The melt spinning significantly improved the cycle stability of the alloys, but it notably decreased the discharge capacity of the alloys.