Hydrogen Storage Potential of XLiH 3 (X = Al, Ga, In, and Tl) Perovskite Hydrides for Clean Energy Applications: A First‐Principles Study

The structural, electronic, mechanical, optical, thermal, and hydrogen storage properties of XLiH 3 (X = Al, Ga, In, and Tl) perovskite‐type hydrides were investigated using first‐principles density functional theory (DFT) calculations within the CASTEP framework. The optimized lattice constants expand from 3.34 Å for AlLiH 3 to 3.77 Å for TlLiH 3 to accommodate the increasing atomic radii of the Group 13 elements. Calculated formation energies (−0.75 to −0.39 eV/atom) and ab initio molecular dynamics (AIMD) simulations at 300 K confirm robust thermodynamic and operational thermal stability across the series. Mechanical analyses reveal a brittle‐to‐ductile transition down the group, with AlLiH 3 exhibiting brittle behavior (Poisson’s ratio = 0.27) while the heavier compounds demonstrate functional ductility. Both GGA‐PBE and hybrid functional calculations reveal metallic behavior with high electrical conductivity. Strong visible‐light absorption and good lattice stability are observed. Notably, AlLiH 3 achieves the highest hydrogen storage capacity (8.19 wt.%), meeting the U.S. Department of Energy (DOE) hydrogen storage target. While AlLiH 3 requires a higher hydrogen desorption temperature (553.66 K), the progressive weakening of the X–H orbital hybridization in heavier cations thermodynamically favors dehydrogenation. This mechanism significantly lowers the required thermal energy for hydrogen release, yielding practical desorption temperatures of 383.87 K for GaLiH 3 , 391.26 K for InLiH 3 , and 287.90 K for TlLiH 3 . These findings highlight the highly tunable nature of XLiH 3 perovskites, positioning them as promising, multifunctional solid‐state materials for advanced clean energy applications.