Fabrication of solid oxide fuel cell components by tape casting method

• Main Author: Zhou, Weixiu.
• Other Authors: Chan Siew Hwa
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Mechanical engineering::Alternative, renewable energy sources
• Online Access: http://hdl.handle.net/10356/39431
• Institution: Nanyang Technological University

Optimization and development of cell and microstructure characteristics with the objective of enhancing cell performance is researched upon globally. Intermediate-temperature anode-supported solid oxide fuel cell (SOFCs) based on gadolinium-doped ceria (GDC) electrolyte is being fabricated by screen printing method in this study. The focus of the research is in optimizing performance of cell by maximizing the maximum power densities, lowering the impedance of intermediate temperature SOFCs based on tape-casted anode. Screen-printing is selected to fabricate the electrolyte of the SOFC single cell assembly as it is an effective, simple, inexpensive and suitable for mass production. The development process starts with electrolyte powder preparation, screen printing and sintering processes. The cell components selected for fabrication includes Nickel oxide-gadolinium-doped ceria (NiO-GDC, weight ratio 65:35) as anode, GDC as electrolyte and Lanthanum strontium cobalt ferrite- gadolinium-doped ceria (LSCF-GDC, weight ratio 50:50) as cathode. Iron oxide and Cobalt oxide are evaluate the effects of sintering aids on maximum power densities, open circuit voltages and improve densification of the cell microstructure. An anode functional layer is also added to further enhance cell performance. Cell performance is examined under hydrogen (50cm3/min) for the anode and atmospheric air for the cathode in the temperature range of 550 to 650°C. Impedance evaluations were recorded in the frequency range of 10mHz to 100kHz with a signal amplitude of 10mV under open circuit conditions. Upon completion of the electrochemical analysis, cross section of the microstructure is examined under the SEM. The best performing unit cell (anode with functional layer) fabricated showed good electrical performance of 755 mW/cm2 and an open circuit voltage 0.8V at 650ºC. Impedance testing shows electrode ohmic and polarization resistance of 0.17Ωcm2 and 0.22 Ωcm2 respectively. It is also discovered that at operating temperatures of 550 to 650°C, the total cell resistance is significantly dominated by electrode polarization resistance (>50%). A 10 by 10 pellet is also successfully fabricated for further testing in the future.