Computational Investigation of Perovskite Hydrides XLiH 3 (X = Fe, Co, Ni) for Solid-State Hydrogen Storage

In this study, three novel perovskite compounds XLiH 3 (X = Fe, Co, Ni) have been investigated for H 2 storage applications. DFT is incorporated to predict the structural, electronic, thermal, mechanical, and optical properties for hydrogen storage applications. The compounds were optimized at every stage of the study, and a cubic phase was observed for all compounds under the simulation criteria. Negative formation energies confirm the thermodynamic stability of the hydrides. All three compounds also satisfy mechanical stability criteria. From the band structure, it was confirmed that the hydrides are metallic, as calculated using both the GGA-PBE and HSE06 functionals. Hardness, machinability index, and fracture toughness were calculated for all three compounds; FeLiH 3 exhibited the highest fracture toughness. The optical absorption peak indicates strong absorption in the visible and near-UV range for all three compounds. In the lower-energy range, the compounds showed a sharp peak in optical conductivity. The gravimetric H 2 storage capacities of the XLiH 3 (X = Fe, Co, Ni) hydrides are 4.59%, 4.39%, and 4.41%, respectively. The volumetric H 2 storage capacities are 187.70, 181.30, and 171.10 g.H 2 /L, respectively. The thermodynamic desorption temperature for FeLiH 3 , CoLiH 3 , and NiLiH 3 are 293.811 K, 303.471 K, and 298.280 K, respectively.