Li adsorption on edge-oxidized graphene nanoribbons predicted by DFT calculations

Motivated by the increased interest in graphene oxide derivatives for Li-ion battery applications, the interaction of Li atoms and various oxygen-terminated graphene nanoribbons was studied using the spin-polarized density functional theory and periodic boundary conditions calculations. Li binding energies were calculated at the edge regions and on the basal plane considering zigzag and armchair morphologies terminated at the edges with different oxygen-containing groups, such as hydroxyl, carboxyl, carbonyl, and ether groups. A relation between the adatom binding energies and the electronic properties of the chemically modified substrate is investigated. The main factors contributing to favorable Li adsorption energies are edge morphologies and sites, electronic behavior, and the presence of ketone groups at the edge. This work suggests that the formation of covalent bonds within Li and certain group terminations could explain the much larger irreversible capacity found in experimentally oxidized carbon materials. Our calculations offer critical information to further optimize the structure of oxidized carbon materials for Li-ion battery applications.