Synthetical designing of solid oxide fuel cell electrodes: Effect of particle size and volume fraction

Solid oxide fuel cell (SOFC) electrode microstructures composed of catalyst, electrolyte and pore phases with various microstructural features are synthetically generated and the effects of the mean particle size and volume fraction of each phase on three/triple phase boundaries (TPBs) are computed. For mono-sized particles with an equal volume fraction, the active and total TPB density are found to decrease with increasing the mean particle size due to decreased surface area. However, both are found to be inversely related to the square of the mean particle size. Active TPB densities of 37.62 mu m mu m(-3), 9.27 mu m mu m(-3) and 4.11 mu m mu m(-3) are obtained from the electrode microstructures with mono-sized particles of 0.25 0.50 mu m and 0.75 mu m mean particle size, respectively. Moreover, similar to 94% of the total TPB density is determined to be active regardless of the mean particle size. TPBs for the polydisperse particles with the same volume fraction also show a decreasing trend with the mean particle size in general. However, no significant change is observed in inactive TPB formations even for the largest particle size investigated, revealing almost fully percolated phases can be achieved when the volume fraction of each phase is equal (similar to 33.3%). On the other, when the volume fractions are also varied, the active TPB is shown to be strongly depended on the volume fraction of the phase having the highest mean particle size. In this regard, among the related cases studied, the lowest active TPB density is computed as 0.25 mu m whereas the highest one is measured as 26.64 mu m. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study synthesized the microstructures of solid oxide fuel cell (SOFC) electrodes and computed the effects of the mean particle size and volume fraction of each phase on three/triple phase boundaries (TPBs). The results showed that the active and total TPB density decreased with increasing mean particle size, but were inversely related to the square of the mean particle size for particles with equal volume fraction. Furthermore, the active TPB density was strongly dependent on the volume fraction of the phase with the highest mean particle size when the volume fractions were varied.