Fabrication and characterization of anode-supported electrolyte thin films for intermediate temperature solid oxide fuel cells

Anode-supported electrolyte thin films for improving the solid oxide fuel cell (SOFC) performance at intermediate temperature (IT) have been manufactured by a wet-chemical process, and their microstructures, gas permeabilities, and electrical performances have been investigated. NiO-YSZ anode supports of a flat tube type were prepared by the extrusion method, and their surfaces were modified via slurry coating of fine NiO-YSZ particles for controlling the surface roughness and the pore size. An anode-supported yttria-stabilized zirconia (YSZ) electrolyte was fabricated by dip-coating YSZ slurry'(viscosity 4.5 cP, solid contents 2.7 vol.%) onto the modified anode support, then it was coated with YSZ sol (viscosity 2.5 cP), and sintered at 1400°C. The cathode consisted of three consecutive layers of LSM-YSZ composite, strontium-doped lanthanum manganite (LSM), and La_0.6Sr_0.4Co _0.2Fe_0.8O_3-δ (LSCF). After each successive slurry layer was applied it was cofired at 1200°C. The thickness of YSZ electrolyte layers could be controlled below 15 μm, and the YSZ layers' acceptability as an electrolyte film for an SOFC was estimated from the result of the gas impermeability ranging below 2 bar. The unit cells fabricated in this work showed a good electrical performance of 550 mW cm^-2 at 850°C. This is attributed to the reduced resistance through the thin YSZ electrolyte.