AB2-type rare earth-based compounds with C-15 structure: Looking for reversible hydrogen storage materials

AB2-type (A = rare earth, B = transition metal) intermetallic compounds with C15 structure can easily absorb large amount of hydrogen, showing their potential use as hydrogen storage materials. The crucial problem hindering their application is hydrogen induced amorphization (HIA), which leads to the irreversible hydrogen sorption process. The stability of the AB2 Laves phase compounds, the structural properties, the hydrogenation properties and the controlling factors of HIA are discussed in this review. Comparing with other factors, the atomic radii ratio rA/rB is the most important one influencing the HIA. Multi-element substitution is an efficient way to suppressing or limiting HIA and may enable AB2 compounds to be suitable for hydrogen storage.