Stable and easily sintered BaCe_0.5Zr_0.3Y _0.2O_3-δ electrolytes using ZnO and Na ₂CO₃ additives for protonic oxide fuel cells

BaCe_0.5Zr_0.3Y_0.2O_3-δ (BCZY) based composite electrolyte materials were fabricated with ZnO sintering aid (BCZY-Z). The effects of Na₂CO₃ modification on sintering behavior, chemical stability and electrochemical performance were systematically investigated. The X-ray diffraction patterns indicate that the specimens with Na₂CO₃ addition possessed a single perovskite structure after sintering at 1320 °C for 2 h. The linear shrinkage of 0.5 mol% Na₂CO₃-modified BCZY-Z sample (BCZY-Z-C2) was about 17.5%, higher than that without Na₂CO ₃ addition (14.9%). Energy dispersive spectrometer shows that Na and C elements still existed and mainly distributed along the grain boundaries. Reactivities with carbon dioxide and boiling water of BCZY-Z and Na ₂CO₃-modified BCZY-Z samples were also evaluated and good chemical stability was observed for Na₂CO₃-modified BCZY-Z samples. A conductivity of 7.68 × 10^-3 S cm^-1 for BCZY-Z-C2 was obtained at 700 °C in 3% wet hydrogen atmosphere. An anode-supported fuel cell with thin-film BCZY-Z-C2 as electrolyte was fabricated. The fuel cell delivered a peak power density of 302 mW cm ² and interface resistance value of 0.08 Ω cm² at 700 °C.