Towards the 3D modeling of the effective conductivity of solid oxide fuel cell electrodes: I. Model development

• An effective conductivity model of a 3D porous microstructure is proposed.
• The model relies on the discretization of a given microstructure into cubic voxels.
• The modelled and analytical effective conductivities agree in general.
• The discretization resolution affects the calculated effective conductivities.
• The required discretization resolution depends on the structure heterogeneity.

The effective conductivity of a thick-film solid oxide fuel cell (SOFC) electrode is an important characteristic used to link the microstructure of the electrode to its performance. A 3D resistor network model that has been developed to determine the effective conductivity of a given SOFC electrode microstructure, the Resistor Network or ResNet model, is introduced in this paper. The model requires the discretization of a 3D microstructure into voxels, based on which a mixed resistor network is drawn. A potential difference is then applied to this network and yields the corresponding currents, allowing the equivalent resistance and hence conductivity of the entire structure to be determined. An overview of the ResNet modeling methodology is presented. The approach is general and can be applied to structures of arbitrary complexity, for which appropriate discretization resolutions are required. The validity of the model is tested by applying it to a set of model structures and comparing calculated effective conductivity values against analytical results.