Study on the ORR Mechanism and CO2-Poisoning Resistance of La0.8Sr0.2MnO3-δ-coated Ba0.5Sr0.5Co0.8Fe0.2O3-δ Cathode for Intermediate Temperature Solid Oxide Fuel Cells

Abstract

The LSM-coated BSCF cathode with 3D core-shell architecture had been fabricated by the solution impregnation technology and presented the excellent CO2-poisoning resistance at the operating temperature. The LSM shell limited the combination of CO2 and BSCF, making that the 3D core-shell cathode present the great CO2-poisoning resistance. The three-electrode measurement was carried out to investigate the ORR mechanism. As the intervention of LSM shell, the LSM-coated BSCF presented the different ORR rate-determining step comparing with the BSCF cathode. The formation of lattice oxygen was the rate-determining step for the LSM-coated BSCF cathode, while molecular oxygen surface adsorption for the BSCF cathode. In addition, the electrochemical stability was promoted greatly with the protection of LSM shell. The LSM-coated BSCF cathode could get the stable state at about 11 h under cathodic current passage of 400 mAcm-2 at 650 °C, while it was about 70 h for the BSCF cathode. The excellent electrochemical performance and CO2-poisoning resistance made that the LSM-coated BSCF cathode appears to be a promising cathode for IT-SOFCs.