Theoretical investigation on materials properties of Li- and Sc-based borohydride LiSc(BH ₄ ) ₄ for H ₂ storage application

In this work, we comprehensively investigate materials properties such as not only structural, electronic, chemical bonding and lattice dynamics properties but also mechanical and dynamical stabilities for Li- and Sc-based borohydride LiSc(BH 4 ) 4 by using first-principles calculations. We make a reliable prediction of lattice parameters, bandgaps, elastic constants, dehydrogenation temperature and materials stability, providing atomic-scale insights into materials properties. Electronic structure calculations demonstrate that LiSc(BH 4 ) 4 and B 2 H 6 have large bandgaps over 4.5 eV and LiB has a small bandgap of ~0.1 eV, whereas ScB 2 has metallic electronic properties with no bandgap. Based on lattice dynamics calculations, we further reveal that all the compounds are dynamically stable at ambient conditions as well as mechanically stable in accordance with Born’s stability criteria. We suggest a dehydrogenation pathway and study energetics for H 2 decomposition of LiSc(BH 4 ) 4 by considering quantum effect, finding that H 2 desorption temperature ranges from 310 to 330 K. This work highlights that the borohydride LiSc(BH 4 ) 4 has high potentiality to be used as a promising H 2 storage material with a high gravimetric capacity of 14.4 wt% and suitable dehydrogenation temperature.