Patent ID: 7569292

Claim:
A solid oxide fuel cell comprising a single cell having an air electrode disposed on a surface of an electrolyte membrane and a fuel electrode disposed on the other surface of the electrolyte membrane, a first electrode reaction layer having open pores interposed between the electrolyte membrane and the air electrode so as to accelerate a reaction of forming oxygen ions from oxygen gas and electrons, a second electrode reaction layer interposed between the electrolyte membrane and the fuel electrode and including NiO and scandia-doped zirconia, and an interconnector having a role of electrical connection; wherein the electrolyte membrane includes only a first layer comprising a material having an oxygen-ionic conductivity of S 1 on the air-electrode side, and a second layer comprising a material containing at least zirconia and having an oxygen-ionic conductivity of S 2 on the fuel-electrode side, with an outer surface of the first layer engaging the first electrode reaction layer, and with an outer surface of the second layer engaging the second electrode reaction layer; and wherein the oxygen-ionic conductivity of S 1 on the air-electrode side and the oxygen-ionic conductivity of S 2 on the fuel-electrode side have a relationship of S 1 >S 2 .