Numerical Study of SOFCs with Transport Properties of Gas and Charged Particles in Composite Electrodes

In this study, the performance of solid oxide fuel cells is numerically analyzed based upon the transport properties of the gas, ions and electrons within the constructed composite electrodes. The electrodes, consisting of active layer and support layer, are constructed with continuous pathways for gas and charged particles. With the porous-media properties obtained from coordination number theory and percolation theory, the effective ionic and electronic conductivities can thus be calculated. For gas species transportation, more realistic tortuosity (hence diffusion coefficient) is calculated through path line integrations of the velocity field from a numerical simulation of flow passing through porous media. These effective diffusivity and conductivity properties together with the porous-media properties are then utilized in the numerical simulations of button cells to investigate the performance of realistic SOFCs. The current model is first applied to a button cell with artificially constructed electrodes for validation purposes. Finally, the polarization curve and impedance behavior of realistic cells with reconstructed microstructures based on experimental observations are investigated for better understanding of SOFCs.