Cr Deposition and Poisoning of BaCo0.8(Zr0.8Y0.2)0.2O3-δ Air Electrode of Protonic Ceramic Fuel Cells

Chromium-forming metallic interconnectors (ICs) are generally used to assemble protonic ceramic fuel cell stacks (PCFCs). Thus, Cr poisoning is a potential threat to the performance and stability of PCFCs. The effects of Cr deposit and poisoning on the performance and stability of a typical BaCo0.8(Zr0.8Y0.2)0.2O3-δ(BCZY) air electrode after polarization with a current density of 0.2 A cm−2for 50 h are investigated. It is found that the BCZY and Cr2O3powder are able to react even at 400 °C. In addition, Cr poisoning affects the chemical stability of BCZY. The humidification of air accelerates the Cr deposition and poisoning of BCZY by promoting the surface segregation of Ba and Cr evaporation from IC, and the main phase of the surface deposit is BaCrO4. When the air humidity increases from 3% to 50%, the deposit layer depth increases from 0.949 μm to 2.870 μm. For the fuel cell exposed to air with a relative humidity of 3% and 50%, the polarization resistance (Rp) increases by 19.9% and 53.3%, while the ohmic resistance (RΩ) increases by 3.5% and 17.1%, respectively. This study lays the foundation for further design of Cr-tolerant air electrodes and the selection of working conditions.