Simulating the Electrical Double Layer Capacitance

In this study, a computational model was developed using commercial finite element analysis package COMSOL Multiphysics (Burlington, MA) to simulate the electrical double layer (EDL) structure and quantify the EDL capacitance for the first time. In the modeling the electrochemical process at an EDL structure was considered by solving the Poisson, Nernst-Plank and Butler-Volmer equations without applying electroneutrality and Boltzmann distributions. Moreover, to consider the effect of charge transfer on the EDL capacitance, the cases with and without redox reactions were modeled. To take advantage of the computational equation solving capability, the dielectric constant inside the compact layer was considered as varying smoothly and continuously, rather than as a constant or a set of constants.