Exploring Ti-rich ternary Laves phase alloys for efficient hydrogen storage

Abstract

Striking an optimal balance between the hydrogen storage properties and cost, while identifying a viable material capable of storing hydrogen under ambient conditions, remains a persistent challenge in the present era. AB2-type laves phase alloys have garnered significant interest due to their hydrogen storage capabilities. This work employs a strategy of utilizing inexpensive Tito occupy either Ni or Al sites, to form Ti-rich alloys, with the aim of enhancing the hydrogen storage properties of Ti-Ni-Al alloys. We used the first- principles approach to systematically explore the structural, electronic, and hydrogen storage properties of Ti-rich ternary Laves-phase alloys. Accordingly, we investigated two Ti-rich alloys for their hydrogen storage capabilities: one with a fixed Al-composition, Ti5Ni3Al4, and the other with a fixed Ni-composition, Ti5Ni4Al3. Our investigation shows that the A2B2 tetrahedral site is the energetically stable site for the hydrogen absorption of these alloys. Specifically, Ti-rich, with fixed Ni-concentration (Ti5Ni4Al3), exhibits a higher hydrogen weight percentage than the fixed Al-concentration (Ti5Ni3Al4). Furthermore, we have included the release temperatures corresponding to the hydrogen concentration. With enhanced kinetics in Ti5Ni4Al3, we conclude that the release temperatures are within the working temperature range for fuel cell applications. Additionally, we have used a thermodynamical model to explore the pressure-composition-temperature (PCT) curves for AB2 type laves phase systems and provided a comparative analysis for the compounds under study. This study offers valuable insights for the development of cost-effective, Ti-Ni-Al hydrogen storage alloys with better hydrogen storage properties.