Investigation on the characteristics of La_(0.7)Mg_(0.3)Ni_(2.65)Mn_(0.1)CO_(0.75+x) (x = 0.00-0.85) metal hydride electrode alloys for Ni/MH batteries. Part I: Phase structures and hydrogen storage

摘要

Metal hydride alloys were prepared based on the La_(0.7)Mg_(0.3)Ni_(2.65)Mn_(0.1)CO_(0.75) formula by adding 0-19 at. percent 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 LaNi_5 phase. With increasing Co addition, the unit cell volumes decrease and the phase abundance of the (La,Mg)Ni3 phase and the LaNi5 phase were changed relatively. P-C-T curves were measured for the La_(0.7)Mg_(0.3)Ni_(2.65)Mn_(0.1)CO_(0.75+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.