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.