Researchers from the U.S. and Thailand have advanced nanoconfined lithium nitride as a rechargeable, high-performing hydrogen-storage material with potential application for hydrogen-powered vehicles.

Hydrogenation forms a mixture of lithium amide and hydride (light blue) as an outer shell around a lithium nitride particle (dark blue) nanoconfined in carbon.A high-capacity lithium nitride hydrogen storage system was studied under nanoconfinement. Pathways for hydrogen uptake and release were demonstrated, both theoretically and experimentally, to be fundamentally changed by the presence of nano-interfaces, leading to significantly faster performance and reversibility.

The viability of complex metal hydrides as hydrogen storage materials is usually limited by slow hydrogen uptake and release. Nanoconfinement -- infiltrating the metal hydride within a matrix of another material such as carbon -- can, in certain instances, speed this process by shortening diffusion pathways for hydrogen or by changing the material’s thermodynamic stability.

Nanoconfinement was shown to impart another, potentially more important consequence: the presence of internal “nano-interfaces” within nanoconfined hydrides can alter which phases appear when the material is cycled.

An advanced thermodynamic modeling method was applied to consider the contributions from the evolving solid phase boundaries as the material is hydrogenated and dehydrogenated. Accounting for these contributions eliminates intermediates in nanoconfined lithium nitride, which was confirmed spectroscopically.

Lawrence Livermore scientists collaborated with an interdisciplinary team of researchers, including colleagues from Sandia National Laboratories Mahidol University in Thailand, and the National Institute of Standards and Technology.