Comparison of Approximate Solution Methods for the Solid Phase Diffusion Equation in a Porous Electrode Model

Approximation methods are often used in porous electrode models to eliminate the need to solve the local solid phase diffusion equation. These ethods include Duhamel’s superposition method, a diffusion length method and a polynomial approximation method which have long been used n the literature. The pseudo steady state (PSS) method is a method that has been used recently to develop a solution to the diffusion equation in spherical particle with time dependent boundary conditions, but the PSS method has not been used in a porous electrode model. These methods re compared to each other in a dimensionless analysis study, and they are used in a porous electrode model to predict the discharge curves for a iCoO2 electrode. Simulation results presented here indicate that the PSS method or the high order polynomial method should be used in a porous lectrode model to obtain accuracy and save computation time. 2007 Elsevier B.V. All rights reserved.