Effect of electrode pore geometry modeled using Nernst–Planck–Poisson-modified Stern layer model

A planar electrode containing cylindrical pores with semi-circular ends is modeled using a finite element implementation of the transient nonlinear 2D Nernst– Planck–Poisson-modified Stern (NPPMS) model. The model uses a modified Stern layer to account for finite ion size. The study includes the effects of pore radius and depth on the predicted electric potential, ion concentration, surface charge density, surface energy density, and charging time. The ion concentration and electric potential are found to be sensitive to the change in radii of the pore and insensitive to the pore depth. The surface charge density is slightly higher within the pore than along the vertical flat regions of the electrode. The increase in surface area due to porosity increases the charging time.