The research findings are published in the Journal of Alloys and Compounds (Q1; IF:5,905).
New efficient methods of hydrogen purification, compression and storage are of great importance for the development and application of hydrogen energy technologies. Metal hydrides and intermetallic compounds are commonly used for these purposes. One of the most promising hydrogen storage materials is magnesium. The use of pure magnesium is limited due to its low resistance to multiple hydrogenation/dehydrogenation cycles and high operating temperatures. Catalytic additives, including aluminum, are used to improve the properties of magnesium.
TPU scientists studied the mechanisms of hydrogen accumulation and desorption in magnesium with aluminum additives.
In the project, the researchers performed a set of calculations and compared them with experimental data. Based on the results, they determined specific features of hydrogen behavior in the Mg-Al-H system depending on its composition and structure. Using these data, the scientists described the mechanisms of hydrogen sorption and desorption adjusted for intermediate phases during phase transition from a solid solution of hydrogen in magnesium to magnesium hydride."Despite the large number of research papers on hydrogen sorption and desorption in magnesium with aluminum, there is a gap as regards the information on hydrogen interaction with aluminum in the magnesium lattice at the atomic level. We used first-principle methods to study the electronic structure of solids. These methods made it possible to study the interaction of hydrogen with aluminum depending on their concentration in magnesium and crystal structure,"
"Depending on the hydrogen content, magnesium can have a different crystal structure and phase. Diffusion rates as well as sorption and desorption rates strongly depend on a temperature and a particular phase of the magnesium-hydrogen system. When pure magnesium is saturated with hydrogen, only a phase transition directly from solid solution to magnesium hydride can be observed. When aluminum atoms are added, an intermediate phase characterized by a higher hydrogen transfer rate occurs. It remains in the process of sorption and desorption long enough in a wide range of hydrogen concentrations. The higher rate of hydrogen transfer allows hydrogen to be sorbed and desorbed faster," explains Leonid Svyatkin, associate professor at the Division for Experimental Physics of the TPU School of Nuclear Science and Engineering.
The results will help improve existing storage materials and develop more efficient technologies for hydrogen separation from mixtures, its compression, and storage at high pressures.
"Creating technological complexes for hydrogen energy is a significant challenge facing scientists and engineers. Application of modern reliable and integral methods of theoretical and experimental research adds to deeper understanding of mechanisms of hydrogen interaction with catalytic additives in hydrogen storage materials and makes it possible to further improve individual elements of the complexes at the stage of their design using the obtained fundamental knowledge. The research findings are important in terms of developing optimal and efficient solutions for the development of complex systems based on metal hydrides,"