Li Storage Feasibility of Defected Single- and Bi-Layer Graphene
Following this approach, we performed an extensive series of density functional theory (DFT) calculations for Li adsorption and intercalation in single and bi-layer graphene, which are activated by topological defects for improving Li adsorption. The results confirm that Li adsorption on defect-free single layer graphene is not thermodynamically favorable compared to bulk metallic Li. However, graphene surfaces activated by structural defects are generally found to bind Li more strongly, with the interaction strength sensitive to both the nature of the defects and their densities. The interaction of Li with a one-dimensional extended defect is additionally found to bestrong, improving Li storage capacity. The theoretical Li storage capacities of the defected single-layer graphene structures are evaluated with a rigorous thermodynamic analysis, which establishes, in some cases, that these capacities approach, although not exceed, those of graphite. Li storage in bi-layer graphene with and without defects are evaluated in a similar way, and indicate more favorable interaction, and promise for higher Li storage than that of single layer graphene. We will present performance comparisons between defected single- and bi-layer graphene structures, and bulk-graphite for Li storage capacities. A detailed analysis of the effect of the van der Walls (vdW) interactions will also be presented.