The effect of strain on hydrogen storage characteristics in KNaAlH double perovskite hydride through first principle method.

Today, hydrogen is one of the most credible options for a non-polluting, carbon-free energy carrier. Hydrogen can be obtained or produced by different means from different renewable energy sources and can be stored in solid, liquid, or gaseous form. Storing hydrogen in complex hydrides in solid form is one of the most efficient methods of storage because they are secure, offer high hydrogen capacity, and demand optimal functioning conditions. Complex hydrides give a large gravimetric capacity that allows large amounts of hydrogen to be stored. This study examined the effects of triaxial strains on hydrogen storage properties of the perovskite-type compound KNaAlH. The analysis was conducted through first principle calculations using the full potential linearized augmented plane wave (FP-LAPW) approach. Our results indicate that the formation energy and desorption temperature of KNaAlH hydride were improved under a maximum triaxial compressive strains of ε ≈ - 5%. Specifically, the values of formation energy and desorption temperature were - 40.14 kJ/mol.H and 308.72 K, respectively, compared to the original values of - 62.98 kJ/mol.H and 484.52 K. In addition, the analysis of the densities of states showed that changes in the dehydrogenation and structural properties of KNaAlH were closely linked to the Fermi level value of the total densities of states. These findings provide valuable insights into the potential of KNaAlH as a hydrogen storage material.