Journal of Power Sources, Vol.167, No.1, 39-46, 2007
Performance of La0.75Sr0.25Cr0.5Mn0.5O3-delta perovskite-structure anode material at lanthanum gallate electrolyte for IT-SOFC running on ethanol fuel
Perovskite-structure La0.75Sr0.5Cr0.5Mn0.5O3-delta (LSCM) powders were prepared using a simple combustion process. Thermal analysis was carried out on the perovskite precursor to investigate the oxide-phase formation. The structural phase of the powders was determined by X-ray diffraction. These results showed that the decomposition of the precursors occurs in a two-step reaction and temperatures higher than 1100 degrees C are required for these decomposition reactions. For the electrochemical characterization, LSCM anode materials and (Pr0.7Ca0.3)(0.9)MnO3 (PCM) cathode materials were screen-printed on two sides of dense La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) electrolyte layers prepared by tape casting with a thickness of about 600 mu m, respectively. The morphology of the screen-printed La0.75Sr0.25Cr0.5Mn0.5O3-delta perovskite thick films (65 mu m) was investigated by field emission scanning electron microscope and showed a porous microstructure. In addition, fuel cell tests were carried out using humidified hydrogen or ethanol stream as fuel and oxygen as oxidant. The performance of the conventional electrolyte-supported cell LSCM/LSGM/PCM while operating on humidified hydrogen was modest with a maximum power density of 165, 99 and 62 mW cm(-2) at 850, 800 and 750 degrees C, respectively, the corresponding values for the cell while operating on ethanol stream was 160, 101 and 58 mW cm(-2), respectively. Cell stability tests indicate no significant degradation in performance has been observed after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 degrees C, suggesting that carbon deposition was limited during cell operation. (C) 2007 Elsevier B.V. All rights reserved.
Keywords:anode;carbon deposition;electrochemical impedance spectroscopy;ethanol;LSGM;solid oxide fuel cell (SOFC)