La0.6Sr0.4Co0.2Fe0.8O3 perovskite cathode for Intermediate temperature Solid Oxide Fuel Cells: A comparative study

In this study the characteristics of two La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) powders, one obtained from an in-house synthesized by co-precipitation method and a commercial one from Fuel Cell Materials Co.(USA), were compared. The co-precipitated powder was processed by using ammonium carbonateas precipitating agent with a NH4+/NO3- molar ratio of 2 and calcination at 1000C for 1 h. Phase composition, morphology and particle size distribution of powders were systematically studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and laserparticle size analysis (LPSA), respectively. The synthesized and commercial LSCF powders were overlaid on Yttria-stabilized zirconia (YSZ) electrolyte having a gadolinium-doped ceria (GDC) interlayer. Electrochemical Impedance Spectroscopy (EIS) measurement was carried out at variousoperating temperatures in the range of 600-850C. XRD and FESEM analysis revealed that single phase nano-crystalline LSCF powder with a mean crystallite size of 14 nm and mean particle size of 90 nm is obtained after calcination at 1000C. The presence of hard agglomerated particles larger thanfew microns in commercial powder and also sub-micron agglomerates in co-precipitated LSCF powder can be related to the final mechanical milling process and high calcination temperature of powders, respectively. LPSA results show identical mean particle size of about 1.5μm for both LSCF powders. EIS results revealed almost identical polarization resistance for both LSCF powders

Keywords:

Perovskites , LSCF , Nanoparticles , Co-precipitation , Cathodes , Solid Oxide Fuel Cells