Industrial & Engineering Chemistry Research, Vol.49, No.13, 6062-6068, 2010
Microstructure and Performance Investigation of a Solid Oxide Fuel Cells Based on Highly Asymmetric YSZ Microtubular Electrolytes
A combined phase inversion and sintering technique was used to fabricate highly asymmetric yttria-stabilized zirconia (YSZ) hollow fibers with a 1.9 mm external diameter and 210 mu m total wall thickness. These consisted of a thin (similar to 10 mu m), dense outer layer and a much thicker (similar to 200 mu m) inner layer with finger-like voids. Such highly asymmetric structures formed gas-tight electrolytes and mechanical supports of a microtubular solid oxide fuel cell (SOFC). Nickel oxide yttria-stabilized zirconia (NiO-YSZ) particles were infused into the pores from alcoholic dispersions and then sintered at 1300 degrees C, prior to electroless Ni layers being deposited, forming composite anodes. The Ni layer deposited by electroless plating had the function of improving the anodic current collection. Cathodes were deposited by slurry-coating lanthanum strontium manganite particles onto the outer surfaces of YSZ hollow fibers, followed by sintering at 1000 degrees C and reduction of the anode at 800 degrees C in a hydrogen environment, completing the fabrication of the microtubular SOFCs. Mechanical strengths of similar to 226 MPa were derived from three-point bending tests on hollow fibers sintered at 1450 degrees C. Initial SOFC performance measurements with 5% H-2 as the fuel and air as the oxidant resulted in maximum power densities of 18 mW cm(-2) at 800 degrees C. This low value resulted largely from the discontinuous nature of the electrolessly deposited nickel anode; present work aims to improve its structure and hence SOFC performance.