Hydrogen storage in lithium-decorated benzene complexes

Based on first-principles calculations, we find Li-decorated benzene complexes are promising materials for high-capacity hydrogen storage. Lithium atoms in the complexes are always positively charged, and each one can bind at most four H2 molecules by a polarization mechanism. Therefore, a hydrogen uptake of 8.6 wt% and 14.8 wt% can be achieved in isolated C6H6–Li and Li–C6H6–Li complexes, respectively. The binding energy in the two cases is 0.22 eV/H2 and 0.29 eV/H2, respectively, suitable for reversible hydrogen storage. Various dimers may form, but the hydrogen storage capacity remains high or uninfluenced. This study provides not only a promising hydrogen storage medium but also comprehensions to other hydrogen storage materials containing six-carbon rings.

► A hydrogen uptake of 8.6 wt% is achievable in an isolated C6H6–Li complex. ► A hydrogen uptake of 14.8 wt% is achievable in an isolated Li–C6H6–Li complex. ► The binding energy is always within several tenths of an eV per H2 molecule. ► Various dimers may form, but the hydrogen storage capacity remains high.