Nanocrystalline Mg-based hydrides: Hydrogen storage for the zero-emission vehicle

Nanocrystalline light metal hydrides are interesting for hydrogen storage in zero-emission vehicles. In this paper, recent detailed results on the sorption behaviour of nanocrystalline Mg and Mg-based alloys are presented. Different transition metals have been added to Mg to achieve a thermodynamic destabilisation of the hydride, thus lowering the desorption temperatures to about 230 degreesC. A breakthrough in sorption kinetics was achieved by using nanocrystalline materials produced by high-energy milling. Additionally, new catalysts based on metal oxides have been added to further enhance the sorption reaction. As a result, hydrogen is absorbed and released within minutes instead of hours as in conventional Mg hydrides. The new materials fulfill the current requirements for the desired application with respect to both, capacity and kinetics.