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Complex Hydrides—A New Frontier for Future Energy Applications


Every energy-related application of hydrogen (H2) requires safe and efficient storage.  H2 can be stored as a compressed gas, a cryogenic liquid, or in an H-rich solid.  The first two approaches require substantial energy for compression or liquefaction, and, therefore, entail multiple containment, safety, and economical issues.  Conversely, H-rich solids are believed to be the best medium to store high-purity H2 required for fuel cells.  Solid hydrides ensure high volumetric density of the fuel because in many of them the volumetric density of H2 at ambient conditions is nearly twice that of a cryogenic liquid at 20 K, reaching 120 g H2/l.  The specific objectives of this FWP are to address issues that will advance basic science of complex hydrides and open up possibilities for their future use by drawing on the experience and expertise of principal investigators in materials science, physics and chemistry of complex hydrides, X-ray diffraction (XRD), high-resolution solid-state nuclear magnetic resonance (NMR), electron microscopy, and first-principles theory and modeling.

This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

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  • Predicted reaction energy path for AlH3 formation on Ti-doped Al(111)

    A defect-mediated direct synthesis of alane (AlH3) from its elements was predicted and verified experimentally. Alane has potential use as a hydrogen storage material with its capacity of 10.1 weight % H2 and relative ease of releasing hydrogen below 100 °C. Alane has not found broad practical use for over 70 years due to difficulties of direct synthesis from its elements.

  • Scientists have designed a simple and direct method for the synthesis of a solid-state hydrogen storage material, alane (AlH3).  Alane, one of the forefront materials for practical solid-state hydrogen storage, has a hydrogen capacity of 10% by weight and gives up hydrogen in a single step at the temperature that is close to the operating temperature of hydrogen fuel cells.  Prior to this work, realizing the enormous potential of alane has been frustrated by the lack of a straightforward method for its synthesis.  The one-step synthesis takes under an hour and can

  • A new recipe for storing hydrogen involves taking magnesium diboride, putting it in a container, adding some hydrogen and ball bearings, and shaking vigorously. Unlike other methods, heating the mixture is not required. Creating a room-temperature-stable, solid-stored hydrogen fuel has been described as one of the grand challenges of science. MgB2 (previously known primarily for its high-temperature superconductivity) has a hexagonal structure of boron sheets separated by layers of Mg.