In this paper, a series of hydrogen storage Co-free AB3-type alloys were directly synthesized with vacuum mid-frequency melting method, and melted alloys were treated by low temperature-short time heat annealing. XRD results indicate that the main phase of melted La0.7Mg0.3Ni3-xFex (x=0.0~0.4) alloys are LaMg2Ni9 and LaNi5 phase. After heat treatment, some LaMg2Ni9 phase transferred into LaNi3 phase because of the loss of Mg during the heat proceeding. The content of Fe element affects phase structure of alloys and led to different electrochemical properties. Heat treatment has positive effects on cycle stability of La0.7Mg0.3Ni3-xFex (x=0.0~0.4) alloys but could cause little reduction of discharge capacity of Fe substituted alloy. However, the discharge capacity of La0.7Mg0.3Ni2.8Fe0.2 alloy increased after heat treatment. The EIS results show that heat treatment has positive effect on H transfer within alloy, and Fe content is related to the diffusion coefficient of H atoms within alloys.

In this paper, First-principles calculation were used to investigate the effect of Fe substituted Co-free AB3-type hydrogen storage alloys. (La3Mg6Ni27)1/3 alloy (Hex structure) and (La3Mg6Ni26Fe1)1/3 alloy's crystal structures were build by Material studio software, Bond structure and DOS results were calculated. To compare with the calculated results, (La3Mg6Ni27)1/3 alloy and (La3Mg6Ni26Fe1)1/3 alloy were synthesized by vacuum melting method. The effect of Fe on such alloys are discussed according to calculate results and experiment results, as a first-principle investigation.

In this paper, the characteristics of melted and annealed Co-free AB3-type hydrogen storage alloys in low-temperature condition were investigated by electrochemical tests. A series of Co-free AB3-type hydrogen storage alloys were synthesized with vacuum melting method, and be annealed by low-temperature heat treatment. The structures of alloys are simply discussed through SEM and XRD results. And discharge ability and cycle ability of alloys were tested. Experiment results indicate that characteristics of different AB3-type hydrogen storage alloys are affected by low-temperature obviously, and heated treatment could increase the discharge capacity of hydrogen storage alloy effectively, and improve the charge-discharge stability of alloy. Furthermore, non-metal element substituted alloy shows better Low-temperature applicability due to its weak crystallization. The discharge capacity of La0.7Mg0.3Ni2.9B0.05 alloy remains 91.2% after 30 cycles at 273K. And discharge capacity of heated La0.7Mg0.3Ni2.9(FeB)0.1 alloy could reach to 250mA·g-1.