Electrochemical hydrogen storage performance of as-cast and as-spun RE-Mg-Ni-Co-Al-based alloys applied to Ni/MH battery
(1. Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, China;
2. Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081, China;
3. Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China)
Abstract: The La-Mg-Ni-Co-Al-based AB2-type La0.8-xCe0.2YxMgNi3.4Co0.4Al0.1 (x=0, 0.05, 0.1, 0.15, 0.2) alloys were prepared via melt spinning. The analyses of the X-ray diffraction (XRD) and scanning electron microscopy (SEM) proved that the experimental alloys contain the main phase LaMgNi4 and the second phase LaNi5. Increasing Y content and spinning rate lead to grain refinement and obvious change of the phase abundance without changing phase composition. Y substitution for La and melt spinning make the life-span of the alloys improved remarkably, which is attributed to the improvement of anti-oxidation, anti-pulverization and anti-corrosion abilities. In addition, the discharge capacity visibly decreases with increasing the Y content, while it firstly increases and then decreases with increasing spinning rate. The electrochemical kinetics increases to the optimum performance and then reduces with increasing spinning rate. Moreover, all the alloys achieve to the highest discharge capacities just at the initial cycle without activation.
Key words: Y; La; substitution; spinning rate; life-span; discharge capacity; electrochemical kinetics