Demonstration of High Durability of Co‐Free Cathode for Protonic Ceramic Fuel Cells in 3000 h Operation

For the practical application of protonic ceramic fuel cells (PCFCs), the development of highly durable PCFCs is essential, and long‐term operation of more than 1000 h must be demonstrated. In this study, a PCFC with a BaZr 0.8 Yb 0.2 O 3− δ (BZYb20) electrolyte, BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3– δ (BCZYYb) porous interlayer, and Co‐free La 0.65 Ca 0.35 FeO 3– δ (LCaF)‐BCZYYb composite cathode was fabricated. The fabricated PCFC exhibited good adhesion between each component. A long‐term durability test was performed on the fabricated PCFC upon constant current operation at 600°C. Initially, a slight voltage drop was observed in the first 500 h owing to an increase in the cathode polarization resistance. After that, the PCFC maintained a near‐constant voltage between 500 and 1000 h of operation. Upon 1000–3000 h of operation, a degradation rate of 0% kh −1 was achieved. No diffusion of all elements of the cathode into the BZYb20 electrolyte was observed by inserting of the BCZYYb interlayer. This study highlights the potential of Co‐free cathodes such as LCaF‐BCZYYb cathode in the fabrication of highly durable and stable PCFCs.