# Reaction Mechanism Study of LiNH2BH3 and (LiH)n (n = 1–5) Clusters Based on Density Functional Theory

## TL;DR

This paper studies how adding (LiH)n clusters affects hydrogen release in LiNH2BH3 using computational methods.

## Contribution

The study reveals the reaction mechanism and energy barriers for hydrogen release in LiNH2BH3 with (LiH)n clusters.

## Key findings

- Hydrogen release in LiNH2BH3 with (LiH)n clusters occurs via Hδ−(Li)···Hδ+(N) with a minimum energy barrier of 113.34 kJ/mol.
- The presence of –BH3 and –LiH groups significantly influences hydrogen release performance in LiNH2BH3–LiH systems.
- Li2AB shows better dehydrogenation performance than LiAB and Li2A.

## Abstract

Hydrogen energy is an ideal clean energy source for the future. In the promotion and application of hydrogen energy, the safe and effective storage of hydrogen needs to be addressed. LiNH2BH3, as an important hydrogen storage material, can reversibly store hydrogen, but it has the problem of a relatively high hydrogen release temperature. (LiH)n plays a good regulatory role in the metal–N–H system and plays an important role. Using density functional theory, the reaction mechanism of LiNH2BH3 and (LiH)n (n = 1–5) clusters was theoretically calculated and analyzed. The frontier orbitals of LiNH2BH3 (LiAB), LiNH2BH3–LiH (Li2AB), and LiNH2–LiH (Li2A) were compared and analyzed, and the dissociation energies of hydrogen atoms at different sites were discussed. The results show that the dehydrogenation of LiNH2BH3 with (LiH)n (n = 1–5) clusters is more likely to occur through the combination of Hδ−(Li)···Hδ+(N), and the minimum reaction energy barrier can reach 113.34 kJ/mol. In the LiNH2BH3–LiH system, the presence of –BH3 and –LiH groups has a significant effect on the hydrogen release performance of the system. The order of hydrogen atom dissociation energies at different positions in LiAB, Li2AB, and Li2A is ΔEH(N) > ΔEH(B) > ΔEH(Li). The dehydrogenation performance of Li2AB is better than that of LiAB and Li2A.