Carbon-based nanomaterials are a promising class of electrodes for electrochemical double layer capacitors, due to their high accessible surface area, high electrical conductivity, and tunability through functionalization. A series of recent studies have shown that chemically and mechanically modified graphene electrodes can have improved capacitance, which has been typically to be associated with the increased double layer capacitance from a high BET surface area or an enhanced electrolyte-electrode interfacial interaction. However, the influence of the electrode’s quantum capacitance is relatively unknown. In this talk, we will present a computational framework based on density functional theory and classical molecular dynamics to explore the relative contributions of the quantum capacitance of electrode (C_Q) and the electric double layer (C_D) capacitance to the total interfacial capacitance (C_T) for various carbon electrode systems in ionic liquids (ILs). For instance, our study suggests that N-doping leads to significant enhancement in C_Q as a result of electronic structure modifications while there is virtually no change in C_D. We will discuss the impact of the chemical and/or mechanical modifications of graphene-like electrodes on the C_T and the design principles to enhance supercapacitor performance.