Assessing co-electrolysis stability with metal-supported solid oxide cells under dynamic current conditions

Solid oxide electrolysis cells are a promising technology for the sustainable conversion of electricity into syngas from H 2 O and CO 2 , enabling the production of low-carbon fuels in Power-to-X applications when coupled with renewable energy sources. Metal-supported cells (MSCs) combine enhanced mechanical robustness and lower material costs with performances similar to conventional ceramic cells. This study investigates the durability of an MSC, manufactured at DTU Energy , operated in co-electrolysis mode with dynamically changing current density, to simulate the integration with wind-solar power sources. The produced syngas composition, measured using a mass spectrometer and a micro-gas chromatograph, closely followed thermodynamic equilibrium, allowing precise control of the outlet H 2 /CO ratio during operation under the examined conditions. Carbon deposition was investigated with a dedicated experiment and observed near the predicted thermodynamic threshold, suggesting good resistance of the studied MSC to coking. The 600-h dynamic durability test was performed with current densities between −0.22 and −0.33 A/cm 2 , under safe operating conditions specifically selected to avoid carbon deposition and to target the desired syngas composition. The cell exhibited a limited degradation rate, with final values between 1 and 3 %/kh at 700 °C. These results demonstrate the strong potential of metal-supported SOECs for efficient, durable, and renewable-driven syngas production. • Degradation rate <3%/kh with dynamic current density in co-electrolysis mode. • Output syngas in thermodynamic equilibrium despite the low electrode's Ni content. • Experimental carbon deposition threshold identified at several operating conditions. • The metal-supported cell with low Ni content shows good resistance to coking.