Effect of Porous Electrode Morphology on Broadband Dielectric Characteristics of SOFC and Methodologies for Analytical Predictions

Abstract

Heterogeneous dielectric material systems and their interfaces which are engineered at the local level (atomic/nano/micro scale) present special challenges for analysis and interpretation of their macroscopic functional behavior in response to specific operational histories. In addition to the chemical composition of the material, the local morphology plays a definitive role in the determination of the transport, electrochemical, and mechanical functions of the heterogeneous constituents, and especially in their interaction and collective action. The basic science of the effect of morphology on polarization, resulting multi-physics properties, and their evolution processes (which determine durability and life) are less well understood. The present paper will focus on a small part of this broader problem. Specifically, the effect of porous microstructure on the broadband dielectric characteristics of the solid oxide fuel cell (SOFC) will be discussed. Different variations of microstructure (such as porosity, pore connectivity, distribution, geometry etc) of YSZ based SOFC materials will be studied using a broadband dielectric spectroscopy system at different temperatures. A finite element based meso-to-continuum model (mm scale model with micron scale features) will be developed to predict dielectric characteristics (voltage, current, impedance distribution) utilizing actual morphology (captured via a 3D X-ray tomography microscope). The paper will summarize all preliminary results from the ongoing research and provide a pathway towards a robust analysis that will help design better microstructures for SOFC electrodes.