A multiscale model for infiltrated SOFC anodes

SOFC electrodes where the electrocatalyst is infiltrated into a porous electrolyte layer offer key advantages such as much higher electrochemical activity, a greater tolerance for thermal shock, higher redox tolerance (for anodes), etc. when compared to conventional composite electrodes. Another important development in recent times is the development of mathematical models that are able to relate the properties of fuel cell electrodes to their microstructure. In this presentation, we will discuss the model development and results from two SOFC models: 1) a model that predicts the effective conductivities and triple-phase boundary density (a measure of reaction site density) using knowledge of the microstructure of Ni infiltrated anodes [1,2], and 2) a multiphysics model that takes the above computed electrode properties and uses them to simulate SOFC performance. The first model, a nano-micrometer scale model is based on percolation theory and uses experimentally controllable and measurable parameters as input. The second model is a micro-centimeter scale reaction-transport model that solves all the relevant coupled physics in a working SOFC to compute the current produced as a function of cell voltage. By coupling the two models together serially, we are able to evaluate the effect of microstructural parameters on fuel cell performance. We will present results that demonstrate how this approach can be used to evaluate and improve the design of infiltrated SOFC electrodes.