Co-Extrusion / Phase Inversion / Co-Sintering for Fabrication of Hollow Fiber Solid Oxide Fuel Cells

Abstract

We have used a co-extrusion / phase inversion process, followed by co-sintering and then NiO reduction with hydrogen, to fabricate anode (Ni-CGO) / cerium-gadolinium oxide electrolyte (CGO) dual-layer hollow fibers (HFs) with inner diameters < 1 mm. This is the first time such dual-layer fibers have been produced as components of SOFCs, thereby decreasing the number of fabrication steps compared with single layer extrusion, while ensuring a gas-tight electrolyte layer of controlled thickness (ca. 60-80 μm). A La0.6Sr0.4Fe0.8Co0.2O3 (LSCF)-CGO cathode ca. 100 μm thick was deposited using slurry coating. Preliminary measurements of the performance of the dual-layer microtubular HF-SOFCs were made with hydrogen flowing at 5 cm3 min-1 and air at 40 cm3 min-1, achieving maximum power densities of 420 W m-2, 800 W m-2 and 1000 W m-2 at 450 oC, 550 oC and 580 oC, respectively. A proposed stack design shows how these micro-tubular SOFCs could be connected in parallel to increase currents and in series for scaling up voltages, aiming at the design of practical stacks.