, Volume 37, Issue 1, pp 15-20
Date: 17 Nov 2006

Electrochemical characterization of perovskite-based SOFC cathodes

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Abstract

The electrochemical performance of La0.58Sr0.4Co0.2Fe0.8O3-δ (L58SCF), La0.78Sr0.2Co0.2Fe0.8O3-δ (L78SCF) and composite La0.65Sr0.3MnO3-δ – 8 mol% Y2O3 stabilized ZrO2 (LSM-YSZ, 50:50 wt%) cathode electrodes interfaced to a double-layer electrolyte made of Ce0.8Gd0.2O2-δ (CGO) and YSZ was studied in the temperature range 600–850 °C using impedance spectroscopy and current-overpotential measurements. The experiments were carried out in a single chamber cell using a three electrode set-up with porous Pt films as auxiliary electrodes. The perovskite powders were synthesized using the spray-drying technique starting from nitrate precursors and were deposited on the solid electrolyte via screen-printing. Open circuit impedance measurements on as-prepared electrodes, i.e. before any polarization, and micropolarization measurements have shown that the L78SCF/CGO/YSZ electrode exhibits the lowest area specific polarization resistance R F (R F was approximately equal to 0.4 Ω cm2 at 800 °C and \(P_{\rm O_2}\)  = 21 kPa) or, equivalently, the highest electrocatalytic activity according to the order: LSM/LSM-YSZ/CGO/YSZ \(P_{\rm O_2}\) (0.01–100 kPa) revealed an exponential increase of the open-circuit area specific polarization conductance \(R_{\rm F}^{-1}\) with increasing \(P_{\rm O_2}\) .