Segmented durability testing of solid oxide electrolysis cells: From model-aided design to proof of concept

Spatially varying degradation in a solid oxide cell (SOC) is often caused by the non-uniform operating conditions inside the electrodes. A prime example of such non-uniform conditions is the distribution in fuel electrode overpotential along the H₂O to H₂ conversion length. To achieve measurements of the varying operational conditions and possible non-uniform degradation rates, a segmented testing approach is introduced. Oxygen electrode segment dimensions and efficiency are analysed and designed based on a 2D multi-physics model. Cells with different fuel electrode microstructures are analysed and the degradation responses measured. Galvanostatic and potentiostatic durability tests are performed with separate measurements of the fuel gas inlet, centre, and outlet segments. Impedance spectroscopy measurements of the segments are further shown in the proof of concept of the segmented testing approach. Differences in the impedance response between the segments provide insights into the local extent of degradation unattainable via a non-segment measurement. The lowered variations in operating conditions due to the segmentation are analysed through the measured gas conversion impedance and multi-physics modelling, confirming the effectiveness of the approach.