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

The La0.8Sr0.2MnO3-delta (LSM)-coated Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) cathode with 3D core-shell architecture has been fabricated by the solution impregnation technology. On the basis of previous research, the synthetic process is improved in order to promote the perovskite degree of BSCF. In this paper, the oxygen reduction reaction (ORR) mechanism of LSM-coated BSCF is studied in detail. As the intervention of LSM shell, the LSM-coated BSCF presents the different ORR rate-determining step comparing with the BSCF cathode. The formation and transfer of lattice oxygen in LSM is the rate-determining step for the LSM-coated BSCF cathode, while the molecular oxygen surface adsorption for the BSCF cathode. In the single cells test, the LSM-coated BSCF cell shows a higher maximum power density than the uncoated cell. The remarkable CO2-poisoning resistant performance of LSM-coated BSCF is verified by the CO2-TPD test and the single cell potentiostatic test. The excellent electrochemical performance and CO2-poisoning resistance indicate that LSM-coated BSCF cathode appears to be a promising cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). (C) 2017 The Electrochemical Society.