Ca-containing Ba0·95Ca0·05Co0·4Fe0·4Zr0·1Y0·1O3-δ cathode with high CO2-poisoning tolerance for proton-conducting solid oxide fuel cells

CO 2 -poisoning effect on cathodes is an unnegligible problem for commercial application of solid oxide fuel cells (SOFCs). In order to enhance CO 2 tolerance of cathodes, partial replacement of Ba by Ca in BaCo 0·4 Fe 0·4 Zr 0·1 Y 0·1 O 3-δ (BCFZY) cathode is proposed in this study. The stability of Ba 0·95 Ca 0·05 Co 0·4 Fe 0·4 Zr 0·1 Y 0·1 O 3-δ (BCaCFZY) and BCFZY in CO 2 -containing atmosphere is investigated comparably. When tested in a symmetrical cell and exposed to air with 1% CO 2 or 10% CO 2 , the electrochemical performance of BCFZY cathode shows obviously degradation and carbonate particles are formed on the cathode surface . Exhilaratingly, the polarization resistance of BCaCFZY cathode is more stable and the cathode surface remains clean. The durability test in proton-conducting single cells further proves that the fine stability of BCaCFZY cathode can be achieved in air with 1% CO 2 atmosphere. In addition, thermodynamic analysis reveals the mechanism of Ca doping to improve stability. Ca dopant itself has a high CO 2 resistance and the introduction of Ca element reduces Ba segregation on surface. Base on the experimental results above, the BCaCFZY cathode is a promising candidate for SOFC applications .