The interaction of lithium with a monolayer of graphene monoxide

The interaction of Li atoms with a graphene monoxide (GmO) monolayer in various Li_xC_yO_y structures is investigated to determine if a monolayer of GmO can bind Li atoms and to predict the maximum theoretical capacity of this potentially new anode material for Li-ion batteries. Ab initio DFT calculations show that Li atoms are adsorbed on GmO by attaching to the O atoms and that Li atoms tend to repel during lithiation. An isolated Li atom prefers adsorption at the hollow site of the C sublattice, although the hollow site of the O sublattice, which is close in energy, may be preferable for multilayer systems. At the highest Li concentration, Li₂C₆O₆ configuration for GmO is energetically stable and has the theoretical capacity of 957 mAh/g, which is 2.6 times higher than capacity of LiC₆ in graphite. Analysis of the band structure and density of states show that the Li donates a large fraction of its valence electron to GmO, although there is also the formation of covalent Li-O bonds, thus facilitating the formation of Li⁺ ions when leaving the GmO monolayer. These characteristics are desirable for the battery anode material and suggest that GmO, especially in multilayer form, is a promising candidate.