Influence of cathode functional layer composition on electrochemical performance of solid oxide fuel cells
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In this work, anode-supported solid oxide fuel cells (SOFC) were tested with a yttria-stabilized zirconia (YSZ) (8 mol% Y2O3-ZrO2)/gadolinium-doped ceria (GDC) (Ce0.9Gd 0.1O1.95) bilayer electrolyte and two lanthanum strontium cobalt ferrite (LSCF) composition as functional cathode layer: La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF 1) and La0.60Sr0.40Co0.2Fe0.8O3-δ (LSCF 2). The functional cathode layers were made of 50 % (w/w) LSCF and 50 % (w/w) GDC. Microstructural characterization was performed by scanning electron microscopy and X-ray diffraction. Electrochemical impedance spectroscopy (EIS) and power measurements were performed under oxygen and hydrogen atmospheres. The microscopy studies showed that the LSCF 2 functional layer is more uniform and adherent to the electrolyte and the cathode collector than the LSCF 1 functional layer, which has cracks, chips, and lower adhesion. The use of the LSCF 2 layer allowed an approximately 25-fold reduction in ohmic resistance (0.06 Ω cm−2) compared with the LSCF 1 layer (1.5 Ω cm−2). The power measurements showed a considerable increase in the power cell using LSCF 2 (approximately 420 mW cm−2) compared with the power cell using LSCF 1 (approximately 180 mW cm−2).
KeywordsSOFC LSCF Interface Electrochemical performance Cathode Functional layer
The authors acknowledge UFMG (Pró-Reitoria de Pesquisa), CNPq (project: 407186/2013-1 and 472767/2013-5), CAPES, FAPEMIG, and CEMIG for financial support and the Center of Microscopy at the Universidade Federal de Minas Gerais for providing the equipment and technical support for experiments involving electron microscopy.
- 26.Dissertações e teses by autor (2014), Minas Gerais, Brazil http://www.bibliotecadigital.ufmg.br/dspace/handle/1843/SFSA-9M4N6G