Effect of Co and Mn on the electrochemical properties of La0.7Mg0.3Ni2(Co+Mn) alloys

The effects of the relative Co and Mn content on the electrochemical performance of La0.7Mg0.3Ni2(Co+Mn) hydrogen storage alloys were investigated. The crystal structure, discharge capacity and cycle life of the alloys were evaluated. For all alloys, we found that the higher the Co content, the larger is discharge capacity. The appropriate amount of Mn in La0.7Mg0.3Ni2(Co+Mn) alloys can extend the cycle life of the hydrogen storage alloys although the alloys have less discharge capacity than those with higher Co content. In addition, the LaNi3.87Mn1.13 phase appears and the LaNi5 phase disappears with replacement of Co by Mn.