Investigation of Sb-based perovskite-type hydrides by using first-principles calculations for advance energy storage

This study employs first-principles calculations based on DFT, as implemented in the CASTEP code, to conduct a comprehensive investigation of the structural, electronic, optical, mechanical and hydrogen storage properties of Sb-based perovskite-type hydrides XSbH 3 (X[Formula: see text]Li, Na, K, Rb). The GGA-PBE exchange-correlation functional was used to optimize the crystal structures, yielding lattice parameters of 4.01, 4.18, 4.26 and 4.30[Formula: see text]Å for LiSbH 3 , NaSbH 3 , KSbH 3 and RbSbH 3 , respectively. The thermodynamic and mechanical stability of both compounds are confirmed through negative formation energy and Born stability criteria, respectively. The results reveal a zero band gap in all materials, establishing their metallic character, which is further corroborated by a detailed analysis of the total and partial densities of states. The optical properties, including the dielectric function, extinction coefficient, refractive index, reflectivity, absorption coefficient, optical conductivity and loss function, are also examined in detail. Mechanical analysis based on the elastic constants confirms that all the studied compounds are mechanically stable. All of the investigated materials are found to be ductile except LiSbH 3 . Further analysis of mechanical properties shows that these materials are anisotropic and harder, as evidenced by their anisotropic index and elastic moduli values, respectively. The gravimetric hydrogen storage capacity is calculated as 2.30, 2.05, 1.85 and 1.44[Formula: see text]wt.% for LiSbH 3 , NaSbH 3 , KSbH 3 and RbSbH 3 , respectively, demonstrating that LiSbH 3 is capable of accommodating a substantial quantity of hydrogen. Thus, this work represents the first theoretical and systematic study of Sb-based perovskite-type hydrides, and its findings can serve as a valuable reference for future experimental synthesis and device-level evaluation of this novel class of hydrogen storage materials.