Efficient hydrogen storage in LiMgF3: A first principle study

The utilization of hydrogen energy as a sustainable and renewable energy carrier has sparked considerable interest, but effective storage remains a challenge. To address this, researchers have turned their attention to hydride materials, which offer safe and efficient hydrogen storage capacity. In this study, we employed density functional theory calculations to investigate the structural and optoelectronic properties of LiMgF3-xHx (x = 0, 1, 2, and 3) hydrides, aiming to gain insights into their potential role in hydrogen storage. The optimized lattice parameter decreases from 3.95 to 3.86 Å with the inclusion of hydrogen. Further, we analyzed the density of states and band structure of each LiMgF3-xHx (x = 0, 1, 2, and 3) perovskite hydride, which depicts the decreasing trend in the bandgap due to increasing concentration of H. The Burstein-Moss shift and bandgap renormalization effects have been determined to assess the shifting of the absorption edge, which results in the narrowing of the bandgap. Furthermore, optical parameters were examined within the range of 0–10 eV, demonstrating a significant redshift in the absorption spectra in the UV region. The alteration in the optical properties and bandgap reduction are discussed in detail. Among the various hydrogen insertions, LiMgH3 displayed the highest static refractive index [n (0) = 2.01] and dielectric function, exhibiting minimal losses in absorption. These results emphasize that LiMgH3 is a promising candidate for hydrogen storage applications. Interestingly, the gravimetric and volumetric hydrogen storage capacities improved significantly from 1.4 to 8.8 wt% and 26.93–86.59 g.H2/l, respectively, which is a consequence of the increasing concentration of hydrogen in the host compound. This work might provide a significant contribution to both present and future research on practical hydrogen storage applications.