Synthesis and characterisation of metal hydrides for hydrogen storage applications

Considering the direction taken for a more sustainable energetic framework, hydrogen could play a crucial role as an energy carrier. One key point relies on the storage technology deployed, which spans from state-of-the-art cryogenic or high-pressure solutions to solid-state storage systems. Thermodynamic and kinetic characterisations, when coupled with structural and morphological analysis, allow us to perform convenient stoichiometric tailoring for cheap, sustainable, fast and secure hydrogen storage systems, resulting in a high-performance material that meets the required operative conditions. The present work exploits the volumetric measurements performed on a Sievert's apparatus coupled with powder XRD, SE-SEM and EDX-SEM analysis to characterise the sorption properties of hydride-forming metals. The first part of the project consisted of the calibration of a Sievert's apparatus, modelling its behaviour in pressure and temperature ranges and characterising reference hydrides such as PdH0.6, LaNi5H6 and Hydralloy C5 (TiZrMnVFe), well-known for their excellent kinetic properties. Furthermore, the novel TiFe90Ni10 alloy has been synthesised, deploying the arc melting technique to explore the concept of elemental substitution for tailoring the thermodynamic properties of the hydride. Nickel substitution in arc-melted TiFe potentially improves the kinetic and thermodynamic properties of the compound, deploying non-toxic and earth-abundant materials. Intense studies have been carried out in the literature on TiFe substitutions, with Ni being an intriguing candidate to reach fast kinetics, good cyclability and low plateau pressures. The comprehensive exploration of elemental substitution in AB intermetallic compounds represents a potential direction for future investigations, seeking a deeper understanding of the metal-hydrogen interaction to optimise the microscopic properties of solid-state storage materials.