Linking Initial Microstructure to Microstructure Evolution and Conductivity Change in SOFC Electrodes: A Phase Field Simulation

摘要

Microstructure evolution driven by thermal coarsening is an important factor for degradation of SOFC electrode. In this work, the effect of an initial microstructure on the microstructure evolution in SOFC electrode is investigated using a recently developed phase field model. Specifically, we tune the phase fraction, the average grain size, the standard deviation of the grain size distribution and the grain shape in the initial microstructure, and explore their effect on the evolution of the grain size, the density of triple phase boundary, the specific surface area and the effective conductivity in Ni-YSZ anode and LSM-YSZ cathode. It is found that the rate of coarsening and property degradation is lower with greater YSZ fraction, greater average grain size, smaller standard deviation of grain size distribution and smaller grain aspect ratio. The implication of this study on the designing of an optimal microstructure of SOFC electrodes is discussed.