Investigation on the characteristics of La0.7Mg0.3Ni2.65Mn0.1Co0.75+x (x=0.00-0.85) metal hydride electrode alloys for Ni/MH batteries Part I:: Phase structures and hydrogen storage

Metal hydride alloys were prepared based on the La0.7Mg0.3Ni2.65Mn0.1Co0.75 formula by adding 0-19 at.% of Co in B-side. The phase structures were obtained from XRD patterns and Rietveld analyses of each alloy. It is found that all alloys consist mainly of the (La,Mg)Ni-3 phase and the LaNi5 phase. With increasing Co addition, the unit cell volumes decrease and the phase abundance of the (La,Mg)Ni-3 phase and the LaNi5 phase were changed relatively. P-C-T curves were measured for the La0.7Mg0.3Ni2.65Mn0.1Co0.75+x(x = 0.00-0.85) alloys at 303 K. The results indicate that the hydrogen absorption capacities decrease, the plateau pressures increase, the hysteresises decrease and the plateau slopes increase. (C) 2004 Elsevier B.V. All rights reserved.