Dresden 2006 – scientific programme

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MM: Metall- und Materialphysik

MM 14: Hydrogen in Metals I

MM 14.1: Talk

Tuesday, March 28, 2006, 10:15–10:30, IFW D

Modified Li-based alanate for hydrogen storage — •Stefania Doppiu, Ludwig Schultz, and Oliver Gutfleisch — IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany

The development of new lightweight materials for hydrogen storage is an important requirement to use hydrogen as fuel for on-board application. Recently, alkali complex hydrides such as Li-alanates have attracted growing interest due to their high gravimetric and volumetric hydrogen densities. Efforts have been done to optimize the overall stability and, as a consequence, the hydriding temperature and the rehydriding pressure, by partial substitution of the alkali metal or the aluminum. In this study, LiAlH4 and LiAlH4 modified by adding MgH2 and TiCl3, subjected to mechanical milling under argon or hydrogen atmosphere, were investigated. Full structural characterization was performed by x-ray diffraction analysis using a full profile fitting procedure (Rietveld). The thermal stability was studied by high-pressure differential scanning calorimetry in a pressure range of 1-150 bar. Milling pure LiAlH4 induces a partial decomposition of the hydride into Li3AlH6. DSC performed on the as-received and the milled samples shows a complex sequence of decomposition steps during heating. In the case of the samples doped with MgH2 and TiCl3, milling under argon induces almost complete decomposition of LiAlH4 into nanocrystalline LiH, MgH2, Al and H2. Further, it is demonstrated that milling under high hydrogen pressure (80 bar) allows to hinder to some extent the undesired decomposition reaction.