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

A series of hydrogen storage Co-free AB₃-type alloys were directly synthesized with vacuum mid-frequency melting method, within which Ni of La_0.7Mg_0.3Ni₃ 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 La _0.7Mg_0.3Ni₃ alloy reaches 37.9 and that of La_0.7Mg_0.3Ni_2.9(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 LaMg ₂Ni₉ phase. Electrochemical tests indicate that substituted alloys have different electrochemical performance, which is affected by phase structures of alloy. The discharge capacity of La_0.7Mg _0.3Ni₃ alloy reaches 337.3 mA·h/g, but La _0.7Mg_0.3Ni_2.9(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.