Lawrence Livermore scientists have collaborated with an interdisciplinary team of researchers, including colleagues from Sandia National Laboratories, to develop an efficient hydrogen storage system that could be a boon for hydrogen-powered vehicles.
Hydrogen is an excellent energy carrier, but the development of lightweight solid-state materials for compact, low-pressure storage is a huge challenge. Complex metal hydrides are a promising class of hydrogen storage materials, but their viability 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, help make this process faster by shortening diffusion pathways for hydrogen or by changing the thermodynamic stability of the material.
However, the Livermore-Sandia team, in conjunction with collaborators from Mahidol University in Thailand and the National Institute of Standards and Technology, showed that nanoconfinement can have another, potentially more important consequence. They found that the presence of internal “nano-interfaces” within nanoconfined hydrides can alter which phases appear when the material is cycled.
“The key is to get rid of the undesirable intermediate phases, which slow down the material’s performance as they are formed or consumed. If you can do that, then the storage capacity kinetics dramatically improve and the thermodynamic requirements to achieve full recharge become far more reasonable,” said Brandon Wood, an LLNL materials scientist and lead author of the paper. “In this material, the nano-interfaces do just that, as long as the nanoconfined particles are small enough. It’s really a new paradigm for hydrogen storage, since it means that the reactions can be changed by engineering internal microstructures.”
The research is reported in the journal Advanced Materials Interfaces