First-Principles-Inspired Design Strategies for Graphene-Based Supercapacitor Electrodes

Using density-functional theory calculations on a variety of model surfaces, we demonstrate that the low theoretical quantum capacitance of graphene-based electrodes can be significantly improved by altering local structural and morphological features. Common point defects, dopants, strain, and surface rippling are considered, as well as differences between locally single-layer and multilayer configurations. Local curvature is particularly effective at improving quantum capacitance, as is the inclusion of certain point defects and substitutional dopants at sufficiently high concentrations. We also show that single-layer graphene exhibits poor screening behavior of the double-layer potential when compared with multilayer samples, which suggests that higher area-specific capacitance can be obtained with samples a few layers thick. Overall, our results demonstrate the viability of local structural engineering as a tool to optimize graphene derivatives for use as supercapacitor electrodes, potentially increasing their theoretical charge storage capacity by severalfold.