Sung-Jin Ahn

Single-Chamber Solid Oxide Fuel Cell with Micropatterned Interdigitated Electrodes

A single-chamber solid oxide fuel cell (SC-SOFC) with micropatterned electrodes on the electrolyte has been fabricated by a microfluidic lithography technique. Microchannels formed by contacting the polydimethylsiloxane mold with a polished substrate of YSZ disk were filled with the well-dispersed suspensions of the cathode and the anode. The suspensions solidified upon solvent evaporation through the mold, resulting in the SC-SOFC with interdigitated micropatterned electrodes in an area of 5 X 5 mm in which each electrode had 100 μm line width with anode-to-cathode distances of 50 μm. I-V characteristics of the SC-SOFC were analyzed using a dc source meter.

Optimum Reduction Condition of SDC-NiO Composite Anode for SDC-based Single Chamber Solid Oxide Fuel Cells

We have determined an optimal reduction condition for NiO-based anode in single chamber solid oxide fuel cells that involve samaria-doped ceria (SDC) as an electrolyte. Optimal condition should not only induce sufficient reduction of NiO to Ni, but also prevent the reduction of SDC electrolyte in order to achieve high open circuit voltage (OCV) and power output. Thermodynamic consideration allowed us to determine the optimal anode reduction condition as 96%H₂-4%H₂O atmosphere at 250℃. This finding was in a good agreement with the experimental verifications by monitoring the conductivities of SDC and NiO under different reducing conditions.

Fabrication of Co-Planar Type Single Chamber SOFC with Patterned Electrodes

Co-planar type single chamber solid oxide fuel cell with patterned electrode on a surface of electrolyte has been fabricated by robodispensing method and microfluidic lithography. The cells were composed of NiO-GDC-Pd or NiO-SDC cermet anode, (La 0.7 Sr 0.3 ) 0.95 MnO₃ cathode, and yttria stablized zirconia electrolyte. The cell performance at 900℃ was investigated as a function of electrode geometries, such as anode-to-cathode distance, numbers of electrode pairs. Relationship between OCV and I-V characteristics at the optimized operation condition was also studied by DC source meter under the mixed gas condition of methane, air, and nitrogen. An increase of anode-facing-cathode area leads to lower OCV due to intermixing between product gases of anode and cathode, which in turn decreases the oxygen partial pressure difference.