Abstract
In this article, recent developments in the field of high-temperature hydrides are discussed with a special focus on MgH2 as a model system. Light-weight hydrides offer high gravimetric storage capacities for hydrogen. However, most of them are too stable for reversible hydrogen storage applications. In addition, reaction kinetics is mostly too sluggish: filling a tank could take several hours. The adoption of high-energy ball milling techniques for achieving nanocrystalline microstructures as well as the discovery of effective and cost-efficient catalysts led to a breakthrough. Moreover, the approach of the reactive hydride composites opens up a way to tailor reaction enthalpies of high-temperature hydrides. Upon desorption, constituents of these different hydrides reversibly react with each other to form a rather stable compound, thus reducing the total reaction enthalpy by the formation enthalpy of the new compound. Using this approach, the range of potential applications of high-temperature hydrides is significantly extended.
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