The effect of B and Fe substitution on the electrochemical properties of AB₃-type Co-free hydrogen storage alloy

In this paper, a series of hydrogen storage Co-free AB₃-type alloys were directly synthesized with vacuum mid-frequency melting method, which are La_0.7Mg_0.3Ni₃, La_0.7Mg _0.3Ni_2.9Fe_0.1, La_0.7Mg _0.3Ni_2.95B_0.05 and La_0.7Mg _0.3Ni_2.9(FeB)_0.1 alloys. XRD results show that the main phases are LaNi₅ phase and LaMg₃Ni₃ phase, and there is LaNi_2.28 phase within La_0.7Mg _0.3Ni_2.9(FeB)_0.1 alloy. The particles of different alloys have different shape and range scale. Melted La _0.7Mg_0.3Ni₃ alloy and (FeB) substituted alloy show better cycle ability than the other two alloys. And (FeB) substituted alloy has batter HRD performance than other alloys, the HRD₅₀₀of which reaches to 73.19%. Substituted alloys are easier being activated than La _0.7Mg_0.3Ni₃ alloy, and show no relation with substituted element. The diffuse of H atom within alloy structure are easier for substituted alloys which is relative with the structure distortion as substitution occurs. The diffusion coefficient of Fe substituted alloy is 7.171×10-9 which is the largest value among alloys in this paper.