Capacitance profile of graphene via effective screening medium method: first-principles study

Abstract Total capacitance of supercapacitors plays an important key to improve energy and power density. To evaluate the total capacitance contributed from quantum and double layer capacitance computationally, a simple model is necessary to reduce computational cost. In this study, we inserted parallel graphene between the metals of an effective screening medium (ESM) to calculate the total capacitance by ESM integrated with density functional theory (DFT) method. We reveal that the net Mulliken-charge and the Hartree-potential difference of the graphene are altered because of an electric field. The charge and potential difference could be utilized to calculate the total capacitance of the capacitor model. The interlayer distance between the graphene plays an important role. Through this study, it could afford insight for a simple method to understand the capacitance behavior in a supercapacitor, especially for the next generation of supercapacitor application.