Investigations on Lithium decorated light weight BeN4 for reversible and enhanced hydrogen storage; an Ab-Initio Molecular Dynamic (AIMD) study

This study investigates the potential of lithium (Li) decorated beryllium tetranitride (BeN4) as a medium for hydrogen (H2) storage and release using first-principles calculations. Our findings demonstrate stable double-sided Li adsorption on BeN4 with no clustering issues, as evidenced by the binding energy per Li atom (>2.88 eV), transition state analysis, and molecular dynamics (MD) trajectory calculations. The Li-decorated BeN4 system achieves an exceptionally high H2 gravimetric capacity of 12.21 wt%, nearly double the U.S. Department of Energy (US-DOE) target of 6.5 wt%, with a favorable adsorption energy range of 0.248–0.37 eV/H2. The interaction between H2 molecules and the Li-decorated BeN4 monolayer is primarily of a weaker covalent nature. Additionally, to assess the reversibility of the Li-decorated BeN4 monolayer for H2 storage, various parameters including desorption temperature (TD), hydrogen occupation number (f), and adsorption distance were examined through MD simulations. The TD for H2 molecules adsorbed on 16Li-BeN4 at 1 atm ranges from 200.9 to 252.8 K, which increases with pressure. Specifically, 16Li-BeN4 can adsorb up to 64 H2 molecules at 30 atm and 298 K and release nearly all H2 molecules at 1 atm and 373 K, making these conditions ideal for adsorption and desorption, respectively.