Exploring the hydrogen energy storage potential of alkali metal tetrahydrometallates through first-principles analysis

In this study, the density functional theory (DFT) approach is employed to explore structural, electronic, optical, thermodynamic, mechanical, and charge-related properties of LiGaH 4 , LiInH 4 , and LiTlH 4 for possible hydrogen storage and optoelectronic applications. These hydrides crystallize in an orthorhombic symmetry with Cmcm (No. 63) space group and exhibit wide bandgaps of about 4.56, 4.55, and 3.93[Formula: see text]eV, respectively. Optical analyses reveal the strong absorption coefficient of up to [Formula: see text] [Formula: see text]cm[Formula: see text] and moderate dielectric response of 3.41 (LiGaH 4 ), 3.24 (LiInH 4 ), and 3.99 (LiTlH 4 ) in the visible to UV region of incident radiation. Dynamic stability is predicted by phonon dispersion and thermodynamic properties, showing consistency up to a 400–600[Formula: see text]K temperature range. Mechanical stability and ductile nature are reported by the mechanical analysis. Charge analysis reveals strong ionic interactions between Li and H. Importantly, being the hydrides, the gravimetric hydrogen storage capacities (GHSCs) are reported to be 5.00[Formula: see text]wt.% (LiGaH 4 ), 3.20[Formula: see text]wt.% (LiInH 4 ), and 1.87[Formula: see text]wt.% (LiTlH 4 ), identifying LiGaH 4 as the promising candidate for hydrogen storage applications. These findings highlight the potential of alkali metal tetrahydrometallates for solid-state hydrogen storage applications, along with their wide bandgaps, making them feasible to be utilized in optoelectronic devices.