Amides/Imides Project

The Amides/Imides Project focuses on the discovery and characterization of metal amide-containing material systems for hydrogen storage. It has been reported in recent years that the interaction between an alkali and alkali-earth metal amide, e.g. LiNH₂, and a metal hydride, e.g. LiH, can enhance the release of hydrogen from the metal hydrides. This "destabilization" effect of metal amide on other metal hydrides have been shown experimentally for a number of light metal hydrides, demonstrating the potential of using this approach for finding an exceptional materials system that meets the technical goals set by the U.S. Department of Energy. However, the development of hydrogen storage materials containing amides faces the same hurdles as do other categories of candidate materials: the reversible hydrogen storage capacity is still unsatisfactory, the temperature of dehydrogenation reaction is still too high, and the kinetic rates of reversible hydrogenation-dehydrogenation reactions are too slow for automobile applications. In order to explore the potential of amide-containing materials and improve their performance for hydrogen storage applications, The Amides/Imides Group is engaged in a comprehensive R&D program to understand the fundamentals of the reaction mechanisms of amide containing materials and find new materials or reactions that can potentially yield higher hydrogen mass content per volume with adequate kinetics for practical purposes.

Partners of the Center that are directly involved, including Sandia National Laboratory, Oak Ridge National Laboratory, JPL, GE, Intermatix Inc., University of Hawaii, University of Nevada Reno, and the University of Utah, concentrate their efforts on a range of complementary research activities:

• Modeling and simulation of the thermodynamic properties of amide-containing materials and their reactions — contributing partners: Sandia National Laboratory
• Fundamental characterizations of these materials using advanced analytical techniques such as NMR, IR, and anelasticity spectroscopy — contributing partners: JPL, University of Hawaii, University of Nevada Reno, GE
• Experimental investigations of novel reactions — contributing partners: University of Utah, Sandia National Laboratory, Oak Ridge National Laboratory, University of Nevada, Reno, and University of Hawaii
• Screening and discovery of catalysts using combinatorial chemistry — contributing partners: University of Utah, Intermatix, Inc, University of Hawaii,
• Develop of novel synthesis processes of various candidate materials — contributing partners: Sandia National Laboratory, Oak Ridge National Laboratory, University of Utah
• Test and evaluation of selected promising materials — contributing partners: Sandia National Lab, GE, HY-Energy Inc., JPL

In the past year, Group C conducted a large amount of research on Li-Mg-N-H and Li-Al-N-H material systems. Significant progress was made in both the fundamental understanding and the discovery of new potentials of amide containing materials. For example, it was found that the reaction between lithium amide (LiNH₂) and lithium hexahydroaluminate (Li₃AlNH₆) can be used to produce reversibly about 7wt% H₂. The complete dehydrogenation of this system requires approximately 300°C. The complete rehydrogenation of this system requires about 140 bar pressure. Although a complete characterization of the kinetics of this material system is still under investigation, the van’t Hoff diagram as shown in the attached figure shows that this material system has the potential to become a useful material provided that the temperature of the dehydrogenation can be decreased further.