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

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 the parallel graphene between the metals of effective screening medium (ESM) and calculate the total capacitance by ESM integrated 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 graphene plays important roles. Through this study, it could afford an insight for a simple method to understand the capacitance behavior in supercapacitor, especially for next generation of supercapacitor application.