This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Over the past decades, the searches for solid hydride materials for hydrogen storage focused on intermetallic compounds that store hydrogen in interstitial spaces in the crystal lattices, or, more recently, on complex metal hydrides that are inorganic salt-like compounds of anions such as [AlH4]-, [NH2]-, and [BH4]-. Light metal ionic hydrides are another class of materials that have high capacity and reversibility. However, these ionic hydrides are thermodynamically too stable. The challenge is to destabilize them without significantly sacrificing their capacities.
Intellectual Merits: Using light metal solid solution alloys (LMSSA) for hydrogen storage is a new approach that has not been investigated in the past. Compared to reactions involving ordered compounds, the hydrogenation and dehydrogenation of random solid solutions have more flexibility for thermodynamic tuning. Recently, preliminary experimental results obtained by the PI and his group have demonstrated that Li-Mg solid solutions can hydrogenate and form solid solutions of their hydrides, i.e. Li-Mg-H3-x, rather than physical mixtures of xLiH+yMgH2. This is a significant discovery because when the relative composition of Li and Mg varies within the solid solutions, the equilibrium pressure of hydrogen varies accordingly. When this approach is extended to meta-stable solid solutions such as Li-Al, ideal hydrogen storage properties are predicted based on basic thermodynamic theory of solutions. Motivated by this discovery, the PIs propose a comprehensive research program to investigate and understand the potentials of a series of light metal solid solution alloys for hydrogen storage. Extensive and systematic experimental studies with theoretical support will be carried out to investigate the thermodynamic and kinetic properties of a series of LMSSA, including Li-Al, Mg-Al, Li-Mg, Li-Mg-Al and Mg-Si. The objectives are to 1) Understand the fundamental thermodynamics of light metal solid solution alloys and their reactions with hydrogen, 2) Establish a new approach for developing hydrogen storage materials based on light metal solid solution alloys, and 3) Establish a database of hydrogen storage properties of light metal solid solutions alloys.
Broader Impacts: Both the scientific research and its integration with education activities proposed in this program have broad implications by addressing current national needs in the energy area as well as addressing long-term educational issues. The integrated education plan consists of the following activities 1) Developing a new course on materials science and technology for energy production, storage, delivery, and conservation; 2) Mentoring of postdoctoral researchers and training undergraduate and graduate students in hydrogen storage materials research; 3) Outreaching to k-12 schools and children from under-represented groups; and 4) Establishing a web site to disseminate research results and educate the public on renewable energy and energy conservation.
