Researchers from the Department of Physics at Mizoram University, India, have conducted a comprehensive study on a class of materials known as double perovskite hydrides, which could potentially revolutionize hydrogen storage for energy applications. The team, led by Dr. R. Lalmalsawma and including R. Zosiamliana, Lalhriat Zuala, Shivraj Gurung, R. Lalmalsawma, A. Laref, A. Yvaz, and D. P. Rai, published their findings in the Journal of Physics: Energy.
The study focuses on complex hydrides with the chemical formula A$_2$BH$_6$, where A can be lithium (Li), sodium (Na), or potassium (K), and B can be aluminum (Al) or silicon (Si). These materials are of interest due to their potential to store hydrogen at high densities, which is a key challenge in the development of hydrogen-powered energy systems.
The researchers performed extensive first-principles calculations using two different computational methods, GGA and hybrid-HSE06 functionals, to explore the properties of these hydrides. They found that all the hydrides they studied are thermodynamically and mechanically stable, meaning they can exist under normal conditions without decomposing or changing their structure.
The electronic properties of these hydrides vary depending on the elements used. Hydrides based on silicon (Si) exhibit semiconducting behavior, while those based on aluminum (Al) are metallic, regardless of the other elements present. The semiconducting hydrides also show high optical absorption in the ultraviolet (UV) range, suggesting potential applications in UV-optoelectronic devices.
For hydrogen storage applications, the researchers found that both Al- and Si-based hydrides meet key benchmarks set by the U.S. Department of Energy (DOE). They achieve gravimetric hydrogen capacities (the amount of hydrogen stored per unit weight of the material) exceeding 5.5 percent when A is Li or Na, and volumetric hydrogen densities (the amount of hydrogen stored per unit volume of the material) greater than 40 grams of hydrogen per liter. Among all the hydrides studied, Li$_2$AlH$_6$ and Li$_2$SiH$_6$ emerged as the most promising candidates due to their outstanding gravimetric hydrogen capacities exceeding 12.0 percent, elevated densities greater than 140 grams of hydrogen per liter, and favorable hydrogen desorption temperature ranges between 450 to 650 Kelvin.
The practical applications of this research for the energy sector are significant. High-capacity hydrogen storage materials are crucial for the development of hydrogen-powered vehicles, grid energy storage, and other applications. The materials studied in this research could potentially be used to create more efficient and compact hydrogen storage systems, helping to advance the transition to a hydrogen-based energy economy.
In conclusion, the researchers have identified a class of materials that show great promise for high-capacity hydrogen storage. Their work provides a solid foundation for further research and development in this area, bringing us one step closer to a sustainable energy future. The research was published in the Journal of Physics: Energy, a peer-reviewed journal dedicated to research on energy-related topics.
This article is based on research available at arXiv.