Abstract
Materials with a greater propensity to store hydrogen have drawn a lot of attention in recent decade because of their possible uses in clean energy systems. By offering effective, sustainable, and eco-friendly substitutes for conventional fossil fuels, these materials are essential in tackling the world's energy problems. We have analyzed the influence of [Formula: see text]-site vacancy on hydrogen storage abilities of potassium-based K(2)LiAlH(6) double perovskite by employing the first-principles technique. For both K(2)LiAlH(6) and K(2)LiH(6), structural and thermo-dynamical stability is attested by computing their volume optimization, tolerance factors and formation energies. The elastic constants reveal a significant reduction towards the external strains when vacancy is created at [Formula: see text]-site. The mechanical properties imply that K(2)LiAlH(6) with or without the vacancy at [Formula: see text]-site, the material possesses brittle characteristics. The electronic properties elaborates that K(2)LiAlH(6) possesses an indirect bandgap of 4.16 eV, whereas for K(2)LiH(6) metallic nature is observed. K(2)LiAlH(6) reveals stronger polarization in the high energy region, whereas K(2)LiH(6) reports higher dispersion in the IR region as predicated via their optical analysis. The hydrogen storage abilities reveal a significant increase in the gravimetric densities which are evaluated from 4.83 to 6.17 wt% and a modest increase is noticed in volumetric densities, which are computed from 41.85 to 44.76[Formula: see text](gH(2)/L) with the creation of [Formula: see text]-site vacancy in K(2)LiAlH(6). It ultimately fulfills the United States department of energy criteria and has indicated its capability to be utilized for hydrogen storage.