Kinetics of oxygen reaction in porous La0.6Sr0.4Co0.2Fe0.8O3-δ-Ce0.8Gd0.2O1.9 composite electrodes for solid oxide cells

Kinetics of oxygen reaction in porous La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and La0.6Sr0.4Co0.2Fe0.8O3-delta-Ce0.8Gd0.2O1.9 (LSCF-GDC) electrodes are systematically studied. Normally, there are two pathways of oxygen reaction in porous LSCF: in reaction region with oxygen exchanging at electrode/air interface, and around electrode/electrolyte interface with oxygen exchanging at electrode/electrolyte/air triple-phase boundary (TPB). GDC in porous LSCF-GDC accelerates oxygen transport and oxygen gas diffusion during oxygen reaction. In addition, because the formation of LSCF/GDC interface increases the length of TPB and affects the geometry of reaction region, oxygen reaction in LSCF-GDC tends to proceed in the TPB pathway. The performance and oxygen reactions of LSCF-GDC are evaluated at 650 degrees C and 850 degrees C. Oxygen reaction in LSCF-GDC is suppressed by CO2, but increasing GDC content is able to improve the CO2 tolerance of electrode. Though the performance reduction by H2O is unobvious, H2O can aggravate CO2 degradation at low temperature. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.