First-principles calculations on the physical properties of Zr-based perovskites LiZrH3 and KZrH3 for potential hydrogen storage applications

Abstract

Hydrogen is a promising alternative to fossil fuels due to its abundance on Earth, clean-burning properties, and non-toxic nature. However, developing efficient storage solutions remains a major challenge. Perovskite-type hydrides have attracted significant interest as potential solid-state hydrogen storage materials, owing to their high storage density and safety advantages. In this study, Density Functional Theory is employed to conduct a comprehensive investigation of the structural, dynamic, mechanical, and optoelectronic properties of XZrH₃ (X = Li and K) to assess their suitability for hydrogen storage. Electronic structure analysis reveals that both materials exhibit metallic behavior. Mechanical properties such as bulk modulus (B), shear modulus (G), Cauchy pressure (C_P), B/G ratio, and Young's modulus (E) are calculated using the Voigt-Reuss-Hill approach. The results indicate that LiZrH₃ exhibits ductile behavior, while KZrH₃ is characterized as brittle. Both compounds are thermodynamically and mechanically stable, as confirmed by their negative formation enthalpies and elastic constants. Furthermore, the calculated gravimetric hydrogen storage capacities of LiZrH₃ and KZrH₃ are 2.99 wt% and 2.27 wt%, respectively, with estimated hydrogen desorption temperatures of 473.76 K and 421.06 K. These findings support the potential of Zr-based perovskite hydrides for next-generation hydrogen storage technologies.