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Hydrogen technologies are crucial to attain a carbon-neutral mobility in the near future. However, this goal requires implementing practical, highly efficient, cost-effective solutions in all aspects of the hydrogen value chain, including storage systems. Hydrogen storage represents, indeed, a key enabling technology for advancing hydrogen-fuelled power systems in the transport sector. Gravimetric and volumetric capacities, safety, refuelling times and compression-related costs are all issues concerning storage systems for hydrogen. In this context, metal hydrides, as hydrogen storage materials, are attracting a growing interest, as they own the potential to achieve high volumetric energy densities and comfortable tank designs while reducing costs and safety concerns. Moreover, the wide variations of their thermodynamic properties among the several classes of materials make them extremely versatile in use. This review article provides a comprehensive overview of the key properties of the most relevant metal hydrides, and a critical analysis is conducted to shed light on their prospective use in mobility. Overall, depending on the specific class, metal hydrides suitable for mobile applications show reversible gravimetric capacities ranging between 1.30 and 1.85 wt%, corresponding to volumetric capacities as high as 90 g/L, and usually present reaction enthalpies of 25–35 kJ/mol. To date, this storage approach still represents a niche in the transport sector. However, this study reveals that its potential has not been unveiled yet. This work dissects the main features of each of the considered materials, discussing benefits and drawbacks, and providing a unique collection of tables and graphs for their most relevant properties. Hence, a unique framework is settled to improve understanding of this hydrogen storage approach, to serve as a reference for further research and specific studies for mobile applications. • A unique collection of material properties for several metal hydrides is provided. • Application of metal hydrides for H2 storage in all main mobility sectors is reviewed. • The potential use of high-capacity MgH2 in vehicles is explored qualitatively. • Criteria for the appropriate design of metal hydride tanks for H2 storage are derived.
Scarpati et al. (Tue,) studied this question.