Physics-based modeling of a low-temperature solid oxide fuel cell with consideration of microstructure and interfacial effects

The main objective of this paper is to develop a physical model for the simulation of heat/mass transport and electrochemical process in a solid oxide fuel cell. The model is then used to evaluate the effects of lowering the operating temperature for a solid oxide fuel cell. This model consists of two submodels, i.e., a micro-scale submodel and a macro-scale submodel. The macro-scale submodel is based on the continuum conservation laws. The micro-scale submodel addresses the complex relationships among the transport phenomena in the electrodes and electrolyte, which includes the transport of electron, ion, and gas molecules through the composite electrodes, electrolyte, and triple-phase boundary region. After integrating the two submodels, the dependence of electrochemical performance on the temperature, global geometrical parameter, and microstructures (porosity, volume fraction and composite ratio, etc.) were assessed.Results demonstrate that for a reduced-temperature solid oxide fuel cell with composite electrodes, its performance is also lowered due to a higher ohmic loss in electrolyte and a slower electrochemical kinetics in the cathode. Among the various microstructure parameters for electrodes, the particle size and TPB length are the most important factors that dominate the performance of a reduced-temperature SOFC. In addition, optimal thicknesses for the electrodes exist. It is believed that the current work will provide a valuable model approach, which can be used to help understand the complex transport phenomena in electrodes and optimize the design of a reduced-temperature solid oxide fuel cell.