New La–Fe–B ternary system hydrogen storage alloys

The new La8Fe28B24-, La15Fe77B8- and La17Fe76B7-type alloys have multiphase structures including LaNi5, La3Ni13B2 and (Fe, Ni) phases. The amount of La3Ni13B2 phase increased and that of (Fe, Ni) phase decreased with an increasing La/(Fe + B) atomic ratio. The measurement of P–C–I curves revealed that the maximum hydrogen capacity exceeded 1.12 wt% at 313 K in the pressure range of 10−3 MPa–2.0 MPa. The alloys exhibited good absorption/desorption kinetics at room temperature, and electrochemical experiments showed that all of the alloy electrodes exhibited good activation characteristics, high-rate dischargeability (HRD) and low-temperature (233 K) dischargeability (LTD).