Hydrogen storage property improvement of La–Y–Mg–Ni alloy by ball milling with TiF3.

Ball milling the powders of Mg-based alloys with transition metal compounds is effective for improving their hydrogen storage performances. In this experiment, the alloys of La 1.7 Y 0.3 Mg 16 Ni + x wt.% TiF 3 (x = 0–10) were prepared through mechanical milling technology. XRD, SEM, HRTEM and granulometry were used to measure the composition and microstructure of alloys. The isothermal hydrogen storage property was measured by a Sievert apparatus. The results reveal that the TiF 3 additive in ball-milled samples transforms into MgF 2 and TiH 2 after the first hydrogen absorption. Adding TiF 3 enhances the crystallinity and reduces the average particle and crystallite sizes of alloys, which is beneficial to accelerating hydriding and dehydriding kinetics. Adding 7 wt% TiF 3 into alloy decreases the dehydrogenation activation energy from 72.2 to 64.0 kJ/mol and improves the hydrogen absorption rate at low temperatures, absorbing 3.50 wt% H in 0.5 min at 323 K. [Display omitted] • La 1.7 Y 0.3 Mg 16 Ni with different TiF 3 additions were prepared by ball milling. • Adding TiF 3 increases crystallinity and decreases average crystallite size of alloys. • MgF 2 and TiH 2 nanocrystals are distributed uniformly on the surface of particles. • 7 wt% TiF 3 -added alloy can absorb 3.50 wt% hydrogen in 0.5 min at 323 K. [ABSTRACT FROM AUTHOR]