An Easily Sintered, Chemically Stable, Barium Zirconate‐Based Proton Conductor for High‐Performance Proton‐Conducting Solid Oxide Fuel Cells

Yttrium and indium co‐doped barium zirconate is investigated to develop a chemically stable and sintering active proton conductor for solid oxide fuel cells (SOFCs). BaZr 0.8 Y 0.2‐x In x O 3‐ δ possesses a pure cubic perovskite structure. The sintering activity of BaZr 0.8 Y 0.2‐x In x O 3‐ δ increases significantly with In concentration. BaZr 0.8 Y 0.15 In 0.05 O 3‐ δ (BZYI5) exhibits the highest total electrical conductivity among the sintered oxides. BZYI5 also retains high chemical stability against CO 2 , vapor, and reduction of H 2 . The good sintering activity, high conductivity, and chemical stability of BZYI5 facilitate the fabrication of durable SOFCs based on a highly conductive BZYI5 electrolyte film by cost‐effective ceramic processes. Fully dense BZYI5 electrolyte film is successfully prepared on the anode substrate by a facile drop‐coating technique followed by co‐firing at 1400 °C for 5 h in air. The BZYI5 film exhibits one of the highest conductivity among the BaZrO 3 ‐based electrolyte films with various sintering aids. BZYI5‐based single cells output very encouraging and by far the highest peak power density for BaZrO 3 ‐based proton‐conducting SOFCs, reaching as high as 379 mW cm −2 at 700 °C. The results demonstrate that Y and In co‐doping is an effective strategy for exploring sintering active and chemically stable BaZrO 3 ‐based proton conductors for high performance proton‐conducting SOFCs.