Fabrication of BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ Skeleton Structure for the Development of High-Performance Nanocomposite Cathodes for Protonic Ceramic Fuel Cells by Nitrate Impregnation

A stable and interconnected skeleton structure is critical for the fabrication of high-performance nanocomposite cathodes by impregnation for protonic ceramic cells (PCCs). This work systematically synthesizes an interconnected BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb1711) electrolyte skeleton structure on a dense BZCYYb1711 electrolyte and introduces three catalytic active materials by nitrate impregnation: the electronic conducting La_0.8Sr_0.2MnO_3-δ (LSM), mixed ionic and electronic conducting La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) and triple conducting PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ (PBSCF). The results indicate that skeleton formation and interconnectivity are strongly associated with sintering temperature, most likely governed by the thermodynamics of densification of Ba-containing electrolyte ceramics. The electrode performance strongly correlates with the activity of the impregnated oxides. The PBSCF impregnated BZCYYb1711 (PBSCF-1711) electrode exhibits the best performance with a low R_p value of 0.06 Ω cm² at 700°C in wet air. The fuel cell with PBSCF-1711 cathode shows a maximum power density of 486 mW cm^-2 at 700°C and demonstrates excellent durability, operating stably for over 700 h in fuel cell (FC) mode and through cyclic fuel cell/electrolysis cell operation at 0.5 A cm^-2 in H₂/wet air for 100 h. This study shows the potential for the development of high-performance air electrodes on a stable and interconnected porous skeleton structure based on nitrate impregnation for PCCs.