LiBH4 a new hydrogen storage material

The challenge in the research on hydrogen storage materials is to pack hydrogen atoms or molecules as close as possible. The density of liquid and solid hydrogen is 70.8 and 70.6 kg m−3, respectively. Hydrogen absorbed in metals can reach a density of more than 150 kg m−3 (e.g. Mg2FeH6) at atmospheric pressure. However, due to the large atomic mass of the transition metals the gravimetric hydrogen density is limited to less than 5 mass%. Light weight group 3 metals, e.g. Al, B, are able to bind four hydrogen atoms and form together with an alkali metal an ionic or at least partially covalent compound. These compounds are rather stable and often desorb the hydrogen only above their melting temperature. Complex hydrides like NaAlH4, when catalyzed, decompose already at room temperature. We have investigated LiBH4, a complex hydride which consists of 18 mass% of hydrogen. The hydrogen desorption from LiBH4 was successfully catalyst with SiO2 and 13.5 mass% of hydrogen were liberated starting already at 200 °C.