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 ZrMgNi₂V₂2 elucidate its high potential for hydrogen storage application.