Hydrogen storage efficiency and optoelectronic properties of structutal, mechanical, and dynamical stable perovskite (Li/Na/K)BH3 hydrides for sustainable energy applications

Alkali-based perovskite hydrides, with their exceptional stability and high hydrogen storage capacity, stand out as highly promising candidates for advanced hydrogen storage technologies. We have analyzed the physical traits of (Li/Na/K)BH3 by using first principles investigation under the density functional theory framework. The exchange correlation effects within the crystal structures are analyzed deeply. The tolerance factor, ground state energies for (Li/Na/K)BH3 confirms structural integrity. All structures are also dynamically stable. The optimized lattice parameters of the studied hydrides are obtained via Birch’s equation of state. Three independent elastic constants and mechanical features for (Li/Na/K)BH3 are explored. The computed moduli are in the order of KBH3 > NaBH3 > LiBH3, which implies that KBH3 is stiffer than the others. For each crystallographic plane, the directional sound velocities are also computed. The electronic band structures reveal the metallic nature of (Li/Na/K)BH3. An in-depth investigation of the optical properties of (Li/Na/K)BH3 has also been carried out. The hydrogen storage features for LiBH3 (12.61 wt%), NaBH3 (7.55 wt%), and KBH3 (5.36 wt%) suggest that the studied hydrides have achieved the energy storage target set by the United States Department of Energy (2025) for metal hydrides.