Long Term Study of High Performance Solid Oxide Fuel Cell Cathodes

LAURA BAQUÉ; ADRIANA SERQUIS; ALBERTO CANEIRO

San Antonio

Seminario; 2010 Fuel Cell Seminar & Exposition; 2010

Fuel Cell Seminar & Exposition

The employment of new electrolyte materials (like gadolinium doped ceria and lanthanum gallate) allowed the development of the intermediate temperature solid oxide fuel cells (IT-SOFC), which represent an alternative to conventional SOFC (with  yttria-stabilized zirconia electrolyte) because of its lower operation temperature (500 - 700ºC) and cost. However, cathode overpotential becomes important at these temperatures, decreasing the cell performance. In that sense, our previous results have shown that nanostructured cathodes present better catalytic activity, although their long term stability is still in doubt.In this work, we present a study of the area specific resistance (ASR) evolution from nanostructured La1-xSrxCo1-yFeyO3-d cathodes, over a continuous measurement period of 1000 hours in air at 500°C. Nanostructured La0.4Sr0.6Co0.8Fe0.2O3-d powders have been synthesized by two different chemical routes: an acetic acid-based and an hexamethylenetetramine (HTMA) based. Two different inks were prepared with powders synthesized by each method, and then deposited onto Ce0.9Gd0.1O1.95 ceramic substrates by spin coating. ASR was determined by impedance spectroscopy technique. In addition, cathodes microstructure and morphology were characterized by X-ray diffraction (XRD) and scanning microscopy (SEM) before and after measurements, in order to identify possible changes which could affect their performance.