In this review paper, a critical assessment of the main degradation processes in three key components of solid oxide fuel cells and electrolysers (negative and positive electrodes and the interconnect) is undertaken, attempting prioritization of respective degradation effects and recommendation of the best approaches in their experimental ascertainment and numerical modeling.Besides different approaches to quantifying the degradation rate of an operating solid oxide cell (SOC), the latest advancements in microstructural representation (3D imaging and reconstruction) of SOC electrodes are reviewed, applied to the quantification of triple-phase boundary (TPB) lengths and morphology evolution over time. The intrinsic degradation processes in the negative (fuel)This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Micro-compression tests were carried out on pillars of 60 µm in diameter, milled by plasma focused ion beam in porous Yttria-Stabilized Zirconia (YSZ) pellets. The fracture properties were determined over a wide range of porosities (33%-63%) for 8YSZ and at a given pore volume fraction of 63% for 3YSZ. The mechanical properties determined from testing were reproducible thanks to the homogeneity of the microstructures. The Young's modulus was estimated as a function of the porosity from the unloading curve of tests stopped before fracture. The experiments conducted until the total rupture allowed measuring the compressive fracture strength, which was found to decrease when increasing the porosity. Specimen tested and unloaded just before the total fracture were cross-sectioned by focused ion beam -scanning electron microscope. A transition was detected from a brittle behavior, with macro-cracks parallel to the direction of solicitation, to a diffuse damage with microcracks, when increasing the porosity.

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