Time-Dependence of Microstructural Evolution and Performance Degradation of Ni/YSZ Electrode in Co-Electrolysis SOEC

To understand the degradation phenomena of the Ni/YSZ cathode in co-electrolysis SOEC, durability measurements are performed on electrode-supported cells using electrochemical impedance spectroscopy. The co-electrolysis (with CO2) cells are compared to the water electrolysis at 1073 K under -1.3 V for 100 h. From the analysis, it is revealed that the cathode resistance increases over the operating time, and this degradation is accompanied by the change in the Ni particle size. The Ni particle size of the co-electrolysis cell is almost similar to the water electrolysis cell. This result is corroborated by the result of the Ni-patterned electrode on YSZ thin film which measured at 1173 K for 100 h in the co-electrolysis operation. The delamination of the Ni-patterned electrodes is observed close to the electrolyte of YSZ. Those results on the electrode-supported cell and the model electrode are discussed to understand the governing factors of the electrode degradation.