High–performance protonic ceramic fuel cells with a PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ cathode with palladium–rich interface coating

This study reports on protonic ceramic fuel cells (PCFCs) that exhibit enhanced performance after the addition of palladium (Pd) interlayers at the cathode–electrode interface. The Pd interlayer is deposited by sputtering on the BaZr_0.2Ce_0.6Y_0.1Yb_0.1O_3-δ (BZCYYb) electrolyte surface, followed by the inkjet printing of PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ (PBSCF) and sintering. The proposed method successfully has produced a Pd layer that was well integrated between the BZCYYb and PBSCF layers, with no undesired reactions or phase formation. The Pd layer is diffused along the inner surface of the porous PBSCF cathode with the desired gradient composition. In our experiment, the fuel cell power is enhanced by up to 60% compared to the untreated PCFCs. In the former, the peak power density of the optimal cell is 420 mW cm⁻², while that of the untreated sample is 260 mW cm⁻² at 500 °C. The long-term stability of the Pd interlayer is confirmed during cell operation. The impedance analysis has revealed that the presence of the Pd significantly enhances the current collection and reduces the polarization impedance at the cathode–electrolyte interface, especially at low temperatures. These results indicate that the proposed method is promising for the fabrication of high-performance and robust PCFCs.