EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The electrodes of solid oxide fuel cells (SOFCs) are porous materials with submicron-scale microstructure. The electrode microstructure has a significant impact on the performance of SOFCs through the transport of ions, electrons, and chemical species, as well as electrochemical reactions. Some of the electrode degradation phenomena are also related to changes in the electrode microstructure due to long-term operation. It is, therefore, important to clarify the relationship between electrode structure and performance by understanding the internal phenomena that proceed within the electrode. Advances in nanoscale 3D imaging techniques, such as focused ion beam scanning electron microscopy (FIB-SEM) and nano-X-ray computed-tomography, have provided access to the details of the complex microstructure of porous electrodes. The 3D imaging first started as an observation of 3D structure, and soon after, methods were developed to quantify the characteristic values of the structure, such as particle/pore size distribution, reaction site density, and tortuosity factor etc. As a result, the 3D structural data have improved the accuracy and reliability of the electrode numerical analysis, revealing the transport phenomena in the electrodes. In this talk, we will briefly discuss the quantification of porous structures based on 3D imaging and its application to numerical simulation of electrodes. Particular attention is payed to the correlation between the structure and the electrochemical performance of electrodes. Recent attempts to improve the performance of electrodes by changing the electrode structure are also presented.