Effect of B and Fe substitution on structure of AB3-type Co-free hydrogen storage alloy

A series of hydrogen storage Co-free AB(3)-type alloys were directly synthesized with vacuum mid-frequency melting method, within which Ni of La0.7Mg0.3Ni3 alloy was substituted by Fe, B and (FeB) alloy, respectively. Alloys were characterized by XRD, EDS and SEM to investigate the effects of B and Fe substitution for Ni on material structure. The content of LaMg2Ni9 phase within La0.7Mg0.3Ni3 alloy reaches 37.9% and that of La0.7Mg0.3Ni2.9(FeB)(0.1) alloys reduces to 23.58%. Among all samples, ground particles with different shapes correspond to different phases. The major substitution occurs in LaMg2Ni9 phase. Electrochemical tests indicate that substituted alloys have different electrochemical performance, which is affected by phase structures of alloy. The discharge capacity of La0.7Mg0.3Ni3 alloy reaches 337.3 mA center dot h/g, but La0.7Mg0.3Ni2.9(FeB)(0.1) alloy gets better high rate discharge (HRD) performance at the discharge rate of 500 mA/g with a high HRD value of 73.19%.