The effect of graphene thickness on alkali metal adsorption determined by first-principles calculations

This study investigates the adsorption of alkali-metal atoms (Li, Na, and K) on one-to-four-layer graphene using first-principles calculations, with relevance to ion batteries and energy storage applications. The adsorption energy, electronic structure, and charge transfer are found to depend on the number of graphene layers. The shift in the Fermi level from the Dirac point decreases with increasing layer number, and the density of states at the Dirac point becomes non-zero beyond two layers. Differential charge density and Bader charge analyses reveal that electrons are predominantly transferred from the adatoms to the top graphene layer, inducing interlayer polarization. The amount of charge transfer increases with the number of layers, though the trend saturates beyond three layers. These fundamental insights into thickness-dependent alkali-metal-graphene interactions may provide a basis for understanding potential applications in ion batteries and energy storage, though practical considerations such as coverage effects and diffusion barriers require further study.