Li‐Based Perovskite X LiH ₃ ( X  = Ti, V, Cr, or Mn) Hydrides for Hydrogen Storage Applications: A First‐Principles Study

In this study, we investigate the structural, electronic, optical, mechanical, and thermal properties of Li‐based transition metal perovskite‐type X LiH 3 ( X = Ti, V, Cr, or Mn) for hydrogen storage using density functional theory (DFT). Thermodynamic stability has been verified by negative formation energies, with −1.40 eV/atom for TiLiH 3 being the most stable. Thermal stability was confirmed through ab initio molecular dynamics (AIMDs) at 300 K, and the mechanical stability determined through Born criteria. Band structure analysis using GGA‐PBE and HSE06 shows metallic character, further confirmed by the nonzero density of states (DOSs) at the fermi level, while partial DOS (PDOS) analysis indicated that these hydrides’ conductivity dictated by transition metals “d” orbital. Mulliken population and charge density maps (CDMs) reveal mixed ionic–covalent bonding, with hydrogen as electron acceptors. Optical properties, including dielectric constant, absorption coefficient, optical conductivity, and loss function confirm their suitability for additional applications such as in UV sensing and plasmonic beyond hydrogen storage assessments. Cauchy pressure ( C p ), Pugh’s ( B / G ), and Poisson ratio ( v ) reveal that TiLiH 3 ( C p = 25.65 GPa, B / G = 2.37, and v = 0.32) and VLiH 3 ( C p = 20.65 GPa, B / G = 2.14, and v = 0.30) are ductile, while CrLiH 3 ( C p = −14.15 GPa, B / G = 1.49, and v = 0.23) and MnLiH 3 ( C p = −34.73, B / G = 1.37, and v = 0.21) are brittle. All the compounds, according to scrutiny, have high bulk, shear, and Young’s modulus, indicating their capacity to store hydrogen and withstand application environments. We also provide an in‐depth depiction of these compounds’ acoustic behavior and the Debye and melting temperatures (631–824 and 1376–2247 K, respectively), which are optimal for absorbing, storing, and desorbing hydrogen. The achieved gravimetric and volumetric hydrogen capacities exceed the DOE benchmark which are for MnLiH 3 , CrLiH 3 , VLiH 3 , and TiLiH 3 are 4.66 wt% (185.54 g H 2 /L), 4.88 wt% (177.58 g H 2 /L), 4.97 wt% (165.5 g H 2 /L), and 5.23 wt% (149.6 g H 2 /L), respectively, while maintaining optimal hydrogen desorption temperature (CrLiH 3 : 344.53 K and MnLiH 3 : 310.02 K). This work offers valuable insights into the study of perovskite‐type hydrides and will be an incubator for future developments in green energy sectors.