Effect of calcination temperature on electrochemical properties of cathodes for solid oxide fuel cells

Abstract

This article is concerned with the electrochemical properties of La 0.6Sr 0.4Co 0.2Fe 0.8O 3 − δ (LSCF) as a cathode with respect to its calcination temperature in solid oxide fuel cells (SOFCs). To determine these properties, LSCF powder was synthesized using a modified glycine nitrate process (GNP), followed by calcinations from 1073 K to 1373 K. Its X-ray diffraction (XRD) patterns gradually sharpened as the calcination temperature increased. Also, the specific surface area of the powder decreased due to particle sintering as the calcination temperature increased. Scanning electronic microscopy (SEM) images from calcined LSCF powder at various temperatures show that the particle shapes are quite similar. However, the particle size slightly increased with increasing calcination temperature. The electrode with LSCF powder calcined at 1273 K showed a lower area specific resistance (ASR) value of 0.68 Ω cm 2 at 973 K than the electrode using commercial LSCF powder. Furthermore, the effect of the sieving process of the cathode powder after wet ball milling on its electrochemical properties was investigated in detail. From particle size analysis, it was observed that the sieved powder, after wet ball milling, shows a bi-modal particle size distribution, whereas the unsieved powder had a single mode distribution. The LSCF electrode with unsieved powder showed a 5 times smaller ASR value than that with the sieved powder.