Study of the Rate Limiting Steps and Degradation of a GDC Impregnated La0.6Sr0.4Co0.8Fe0.2O3-δ Cathode

JULIAN ASCOLANI YAEL; A. MONTENEGRO HERNÁNDEZ; H.TROIANI; L.MOGNI; A. CANEIRO

ECS transactions

The electrochemical society

Año: 2017

1938-6737

In this work, a Solid Oxide Fuel Cell (SOFC) cathode surfacemodification by nanoparticle impregnation was carried out.La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) ceramic cathodes impregnated withCe0.8Gd0.2O3-δ (GDC) nanoparticles were characterized withscanning (SEM) and transmission (TEM) electron microscopy. Theelectrochemical response as a function of temperature, oxygenpartial pressure (pO2) (10-4 < pO2< 1 atm) and time was evaluatedby electrochemical impedance spectroscopy (EIS). We obtainedreproducible and homogeneous impregnations, which reduce thetotal cathode´s polarization resistance more than 20% in thetemperature range between 400ºC and 800ºC and during 500 h at700ºC. The impregnated cathode was found to beelectrochemically limited by the same processes as the nonimpregnatedcathode, namely gas diffusion, ion bulk diffusion anddissociative adsorption. The impregnation produced a reduction ofmore than 20% of the oxygen surface resistance; such differenceremained stable through 500h of continuous operation at 700ºC.Introduction