Stable solid oxide electrolysis cells with SSF-based symmetrical electrode for direct high-temperature steam electrolysis

In order to solve the oxidation problem of the Ni-based solid oxide electrolysis cells (SOECs), SOECs with symmetrical electrode Sm0.5Sr0.5FeO3-delta- Gd0.1Ce0.9O2-delta (SSF-GDC) were systematically investigated, including the steam partial pressure, the working temperature, the electrolysis voltage. The reversible symmetrical cells with SSF-GDC electrode under humidified hydrogen presented good reversibility, and the maximum electrolysis current density was 1025 mA cm-2 at 800 degrees C with the applied voltage of 2V. In the case of direct N2 with 20% steam partial pressure as fuel, the symmetrical cells generated the maximum electrolysis current density increased from 267 to 1560 mA cm-2 at 650-800 degrees C. The influence of the steam partial pressure on the steam electrolysis showed that the maximum electrolysis current densities increased with the increase of the steam partial pressure from 3% to 20%, and the steam electrolysis with 3% steam partial pressure showed obvious concentration polarization due to insufficient steam partial pressure at high electrolysis current density. Finally, the short-term stability at different electrolysis voltages and long-term stability at the electrolysis voltage of 1.5V showed that there was no attenuation after 25 h operation, indicating that SSF-based symmetrical electrodes cab be an alternative to Ni-based fuel electrode materials for high-temperature steam electrolysis.

Automated summary

The study found that symmetrical SOECs with SSF-GDC electrodes showed good electrolysis performance under different working conditions, with potential to replace nickel-based fuel electrode materials, and the steam partial pressure had a significant impact on the electrolysis effect.