Structure and electrochemical hydrogen storage characteristics of the as-cast and annealed La_0.8-xSmxMg_0.2Ni_3.15Co_0.2Al_0.1Si_0.05 （x=0-0.4） alloys

李平¹，候忠辉²，杨泰²，尚宏伟²，曲选辉¹，张羊换²

1. School of Materials Science and Engineering, University of Science and Technology Beijing2. Elected State Key Laboratory, Inner Mongolia University of Science and Technology

摘 要：In order to ameliorate the electrochemical cycle stability of the RE-Mg-Ni based A2B7-type electrode alloys, the Mg content in the alloy was reduced and La in the alloy was partially substituted by Sm. The La0.8-xSmxMg0.2Ni3.15Co0.2Al0.1Si0.05 （x=0, 0.1, 0.2, 0.3, 0.4） elec-trode alloys were fabricated by casting and annealing. The microstructures of the as-cast and annealed alloys were characterized by XRD and SEM. The electrochemical hydrogen storage characteristics of the as-cast and annealed alloys were measured. The results revealed that all of the experimental alloys mainly consisted of two phases: （La,Mg）2Ni7 phase with the hexagonal Ce2Ni7-type structure and LaNi5 phase with the hexagonal CaCu5-type structure. As Sm content grew from 0 to 0.4, the discharge capacity and the high rate discharge ability （HRD） first in-creased and then decreased for the as-cast and annealed alloys, whereas the capacity retaining rate （S100） after 100 cycles increased continuously.

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