Study of La0.6Sr0.4Co1-xFexO3-δ (x = 0.2 & 0.8) electrochemical response as SOFC cathode and its relation with microstructure

ALEJANDRA MONTENEGRO HERNÁNDEZ; SCOTT A. BARNETT; ASCOLANI-YAEL JULIAN; Q. LIU; LILIANA MOGNI

PyeongChang

Conferencia; 22nd International Conference on Solid State Ionics (SSI-22); 2019

This work presents the study of the O2-Reduction Reaction (ORR) by electrochemical impedance spectroscopy of La0.6Sr0.4Co0.8Fe0.2O3-δ and La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes as a function of temperature and pO2. The combination of the impedance data, modeled with a Transmission Line Model, with the microstructural data obtained by FIB-SEM tomography, allowed to obtain and compare the chemical diffusion coefficients (D_chem), O2 equilibrium molar exchange rates (R_0) and the oxygen surface exchange rates (k_chem) for both compounds. The obtained values were, at 700 °C in air, D_chem=5.9〖.10〗^(-8) 〖cm〗^2 〖.s〗^(-1) and k_chem= 1.4.〖10〗^(-6) cm.s^(-1) for La0.6Sr0.4Co0.2Fe0.8O3-δ, while D_chem=2.6〖.10〗^(-6) 〖cm〗^2 〖.s〗^(-1) and k_chem= 3.1.〖10〗^(-6) cm.s^(-1) were obtained for La0.6Sr0.4Co0.8Fe0.2O3-δ. The detailed analysis of these parameters as a function of pO2 (〖10〗^(-4)