Synthesis and Hydrogen Storage Properties of a Single-Phase Magnesium Borohydride Mg(BH4)2

A single phase Mg(BH4)2 was successfully synthesized and its hydrogen storage properties were systematically investigated. Depending on the synthesis conditions, Mg(BH4)2 forms low- and high-temperature phases with different crystal structures. The dehydriding reaction of Mg(BH4)2 starts at approximately 500 K, and 14.4 mass% of hydrogen is released through a multi-step reaction. Furthermore, 6.1 mass% of hydrogen can be rehydrided for the sample of Mg(BH4)2 after the dehydriding reaction, through the formation of a possible intermediate compound such as MgB12H12.