Model based evaluation of the electrochemical reaction sites in solid oxide fuel cell electrodes

Abstract

The electrode microstructure plays an important role in determining the performance of the Solid Oxide Fuel Cells (SOFCs). The conventional SOFC electrodes are based on two kinds of particles, one electron conducting and another ion conducting. Over the years, electrodes with alternative microstructures have been proposed for performance enhancement based on the developments in materials and fabrication techniques. Analytical models for the microstructure offer the scope of quick evaluation of the effect of various microstructural parameters on important microstructural properties like the triple phase boundary densities. However, validation of these models in the light of the experimental data is seldom reported. In this work, the microstructural data derived from image-based reconstruction of the electrodes is used to calibrate and validate an analytical model for the conventional SOFC electrode microstructure revealing insights into the model's applicability. This model forms the basis for the models of other modified microstructures studied in this work. Designing of improved SOFC microstructures require an understanding of the effect of controllable parameters on the reaction sites. Model based evaluation of the electrochemical reaction sites in five different SOFC microstructures is performed in this work. The results and insights will enable the selection of microstructural parameters for tailoring the electrode microstructure to achieve improved performance.