Characterization of SOFC Cathodes Prepared by Pulse Laser Deposition

NAPOLITANO, FEDERICO; BAQUÉ, LAURA; CHO, S.M.; QING, S.; WANG, H.; CANEIRO, ALBERTO; SOLDATI, ANALIA L.; SERQUIS, ADRIANA C.

Montreal, Canada

Simposio; 219th ECS Meeting &Twelfth International Symposium on Solid Oxide Fuel Cell Cells (SOFC-XII); 2011

ECS - The Electrochemical Society

Thin film solid oxide fuel cells (SOFCs) have attracted world-wide research interest for compact and highefficiency power applications. It was previously reported that the microstructural variations in the electrolyte and electrode could affect the reaction kinetics of thin film SOFCs dramatically.[1–5] The majority of power losses in planar SOFCs occurs as a result of the polarization resistance at the cathode/electrolyte interface. In particular, some characteristics such as grain size, surface morphology, porosity, path tortuosity, and material composition play an important role on the properties of the cathode layer and the kinetics of the oxygen reduction reactions (ORR) taking place in it [6-8]. In order to further increase SOFC performance, it is necessary to understand how the microstructure of the composites electrodes affects the performance of the system. In this work, we study the electrochemical performance of La1-ySryCo1-xFexO3-d (LSCF) and La0.4Sr0.6Ti1-xCoxO3-d (LSTC) cathodes prepared by pulse laser (PLD) deposition. This technique allows the growth of nanostructured cathode layer with vertically-aligned nanopores (VANP) [8]. In some samples, in order to increase the reaction probability, a vertically aligned nanocomposite (VAN) layer was successfully introduced between the cathode and electrolyte [9]. The binary VAN interlayer is a composite of cathode and electrolyte materials, in this case, LSCO and Ce0.9Gd0.1O1.95 (CGO), respectively. The structure, morphology and composition of several film thicknesses were characterized by X-ray diffraction, transmission and scanning microscopy, and energy dispersive spectroscopy, respectively. The influence of the microstructure on the transport properties is evaluated by means of impedance spectroscopy, under different oxygen partial pressures, in order to study the ORR mechanisms. The electrochemical properties of these cathodes films strongly depend on the microstructure and morphologies and cathode polarization resistance can decrease considerably if optimized synthesis parameters are used.