Numerical Analysis of Electric Double Layer Capacitors with Mesoporous Electrodes: Effects of Electrode and Electrolyte Properties

Abstract

A theoretical study is presented of the behavior of electric double layer (EDL) supercapacitors constructed from mesoporous activated carbon electrodes. A three-dimensional (3D) computational model is developed to predict the equilibrium charge distribution within the supercapacitor as a function of key electrode and electrolyte properties. The model is based on the modified Poisson–Boltzmann (MPB) equation and takes into account the impact of critical device parameters, including the size of the ions, the bulk ion concentration, the field-dependent permittivity of the electrolyte, the specific surface area of the electrodes, and the applied voltage. A key feature of the MPB model is that it limits the accumulation of ionic charge at the electrode–electrolyte interface by accounting for the finite size of the ions. This provides more accurate predictions of capacitance than models based on a point charge approximation. The model is used to perform a systematic parametric analysis of device performance and...