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

Abstract 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.% 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)Ni 3 phase and the LaNi 5 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.