Recent progress in magnesium borohydride Mg(BH4)2: Fundamentals and applications for energy storage

Magnesium borohydride (Mg(BH4)2) shows interesting properties both from fundamental and applicative points of view. Mg(BH4)2 has the most complex crystal structures and the largest number of phase polymorphs among other borohydrides. Some of these polymorphs possess a significant porosity, and on the other hand ultra-density with the second highest volumetric hydrogen content among all known hydrides. Additionally, Mg(BH4)2 demonstrates the lowest theoretical stability, the lowest temperature of hydrogen release, and the mildest conditions for partial rehydrogenation among the alkali and alkaline-earth borohydrides. Mg(BH4)2 could also be of interest in batteries applications, since Mg metal holds better volumetric capacity and is more abundant than Li. In this work we review recent results on synthesis, structure, hydrogen storage properties and battery-related applications of Mg(BH4)2.