Reversible hydrogenation of AB2-type Zr–Mg–Ni–V based hydrogen storage alloys

The development of hydrogen energy is hindered by the lack of high-efficiency hydrogen storage materials. To explore new high-capacity hydrogen storage alloys, reversible hydrogen storage in AB2-type alloy is realized by using A or B-side elemental substitution. The substitution of small atomic-radius element Zr and Mg on A-side of YNi2 and partial substitution of large atomic-radius element V on B-side of YNi2 alloy was investigated in this study. The obtained ZrMgNi4, ZrMgNi3V, and ZrMgNi2V2 alloys remained single Laves phase structure at as-annealed, hydrogenated and dehydrogenated states, indicating that the hydrogen-induced amorphization and disproportionation was eliminated. From ZrMgNi4 to ZrMgNi2V2 with the increase of the degree of vanadium substitution, the reversible hydrogen storage capacity increased from 0.6 ​wt% (0.35H/M) to 1.8 ​wt% (1.0H/M), meanwhile the lattice stability gradually increased. The ZrMgNi2V2 alloy could absorb 1.8 ​wt% hydrogen in about 2 ​h ​at 300 ​K under 4 ​MPa H2 pressure and reversibly desorb the absorbed hydrogen in approximately 30 ​min ​at 473 ​K without complicated activation process. The prominent properties of ZrMgNi2V2 elucidate its high potential for hydrogen storage application.