Cathode-supported SOFCs enabling redox cycling and coking recovery in hydrocarbon fuel utilization

Although cathode-supported solid oxide fuel cells (SOFCs), characterized by significantly thinner anode layers than anode-supported SOFCs, are known to have unique advantages in ensuring stability and reliability against redox operating conditions and carbon deposition, they have received relatively less attention due to their lower performance. Furthermore, there is a lack of in-depth theoretical and experimental studies on their outstanding redox cycle characteristics than the anode-supported cells. Here, applying a sintering aid to the electrolyte considerably reduces the sintering temperature of the electrolyte, with the shrinkage and microstructure of the cathode effectively controlled to lower the diffusion resistance. Consequently, the operating temperature was lowered by more than 100 °C compared to previously reported cathode-supported SOFCs; moreover, at 650 °C, a maximum power density more than twice that reported in previous reports. The redox stability of the cathode-supported cells was demonstrated experimentally and theoretically through a redox cycling test and a 3-D finite element method-based SOFC structure model. Moreover, the outstanding redox cycle property of cathode-supported cells has been experimentally demonstrated for the first time to have the potential to mitigate carbon deposition that occurs when utilizing methane fuel. Hence, this study presents new insights for achieving stable and reliable SOFC operation.