Patent ID: 7422822

Claim:
A single cell for a low operating temperature solid oxide fuel cell, the single cell comprising: a first solid electrolyte having an oxide ion conductivity at 800° C. of at least 0.015 S/cm and a bending strength of at least 600 MPa; a fuel electrode having a first surface bonded to a first side of the first solid electrolyte, the fuel electrode comprising a cermet of a catalyst and a second solid electrolyte having an oxide ion conductivity at 800° C. of at least 0.08 S/cm; an air electrode bonded to a second side of the first solid electrolyte, the air electrode comprising a compound of a first perovskite type oxide with a third solid electrolyte; and an intermediate layer comprising a fourth solid electrolyte interposed between a first surface of the air electrode and the second side of the first solid electrolyte; wherein the first perovskite type oxide is at least one perovskite type transition metal oxide selected from the group consisting of La 1-x Sr x Co 1-y Fe y O 3 (wherein 0.2≦x≦0.6, 0.6≦y≦0.9), Pr 1-x Sr x MnO 3 (wherein 0.2≦x≦0.6) and La 1-x Sr x CoO 3 (wherein 0.1≦x≦0.6) and wherein the third solid electrolyte is a mixed solid electrolyte comprising one of yttria-stabilized zirconia containing 8 to 10 mol % Y 2 O 3 , scandia-stabilized zirconia containing 9 to 12 mol % Sc 2 O 3 , a ceria-based solid solution containing 10 to 35 mol % of at least one oxide selected from the group consisting of Gd 2 O 3 , Y 2 O 3 and Sm 2 o 3 , and combinations thereof.