Triple phase boundary specific pathway analysis for quantitative characterization of solid oxide cell electrode microstructure

The density and percolation of Triple phase boundary sites are important quantities in analyzing microstructures of solid oxide fuel cell electrodes from tomography data. However, these measures do not provide descriptions of the quality of the TPB sites in terms of the length and radius of the pathways through which they can be reached. New methods for performing TPB specific pathway analysis on 3D image data are introduced, analyzing the pathway properties of each TPB site in the electrode structure. The methods seek to provide additional information beyond whether the TPB sites are percolating or not by also analyzing the pathway length to the TPB sites and the bottleneck radius of the pathway. We show how these methods can be utilized in quantifying and relating the TPB specific results to cell test data of an electrode reduction protocol study for Ni/Scandia-and-Yttria-doped-Zirconia (Ni/ScYSZ) anodes. A study of the TPB density and particle size distribution alone did not provide an explanation for the differences observed in electrode performance. However, the analysis of pathway lengths to the TPBs and the bottleneck radii to reach these TPB sites provided valuable microstructural insight that supported the findings from the electrochemical characterization of the Ni/ScYSZ anodes.