Critical Role of In-Situ-Generated Eutectic Carbonates in Superstructured Solid Fuel Cells

As a distinct type of fuel cell, a carbonate-superstructured solid fuel cell (CSSFC), which possesses excellent performance and easy fabrication as well as low cost, was recently invented by our group. Herein, we demonstrated the critical role of the in-situ-generated eutectic carbonate phase in CSSFC. Namely, the in-situ generation of eutectic Li₂CO₃/Na₂CO₃ system increased the oxygen ionic conductivity of Ce_0.8Sm_0.2O_1.9 solid electrolyte by 20 times (from 3.5 × 10^-3 to 7.3 × 10^-2 S cm^-1), leading to 6 times enhancement of CSSFC peak powder density (up to 206 mW cm^-2) with methane fuel at 550 °C. This finding is extremely important for designing efficient CSSFCs.