Theoretical investigation of hydrogen storage in metal-intercalated graphitic materials

We have used first-principles methods to investigate how metal atoms dispersed in the interlayer space of graphitic materials affect their hydrogen-binding properties. We have considered ideal stage-one metal-intercalated graphites of various compositions as representative model systems. Our calculations suggest that alkaline earth metals can significantly enhance the hydrogen-storage properties: for example, Be and Mg atoms would act as binding sites of three or four hydrogen molecules, with binding energies per H-2 in the 0.2-0.7 eV range, as required for applications. We also find that alkali and transition metals are not as effective in enhancing the storage capacity.