Quantum Capacitance Estimations of Pyrrolic-Rich Graphene for Supercapacitor Electrodes

Abstract

Despite having remarkable surface area (2630 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /g for graphene), the graphene-based supercapacitors are still unable to attain the necessary energy density due to poor accessibility of surface area and low quantum capacitance. In this paper, we demonstrate an effective way to improve the quantum capacitance of graphene through plane wave density functional theory calculations. We used pyrrolic-type nitrogen doping to demonstrate extremely high quantum capacitances for graphene. An impressive 486.32 μF/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> quantum capacitance has been observed at a pyrrolic concentration of 6.38%. Our calculations suggest that the quantum capacitance of graphene increases with the pyrrolic concentration. We have also investigated the impact of combinational pyrrolic defects on the quantum capacitance of graphene. We believe that the pyrrolic defects studied in this paper also help in improving the graphene surface area accessibility by the electrolytic ions.