Electrolyte-cathode assembly for a fuel cell

• US 4,130,693 A
• Filed: 05/27/1977
• Issued: 12/19/1978
• Est. Priority Date: 05/28/1976
• Status: Expired due to Term

• Current Assignee: Helmut Tannenberger, Paul Van Den Berghe
• Original Assignee: Helmut Tannenberger, Paul Van Den Berghe
• Inventors: Tannenberger, Helmut, Van Den Berghe, Paul
• Primary Examiner(s): Skapars, Anthony
• Application Number:
  US05/801,392
• Time in Patent Office: 571 Days
• Field of Search: 429/40, 429/41, 429/44, 252/62.2, 252/461, 252/463
• US Class Current: 429/482
• CPC Class Codes: H01M 4/9025 Oxides specially used in fuel cell operating at high temperature, e.g. SOFC
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An electrolyte cathode assembly for a solid electrolyte fuel cell suitable for operation at high temperatures comprises a gas-tight body made of a solid ceramic electrolyte which is capable of conducting oxygen ions having in contact with it and secured to it a layer of electron-conducting material which is a mixture of doped indium oxide In₂ O₃ and a ceramic material which is capable of conducting oxygen ions at the cell operating temperature, the said layer being covered by a compact surface layer of a ceramic material which is capable of conducting both electrons and oxygen ions.

Claims

1. An electrolyte-cathode assembly for a solid electrolyte fuel cell suitable for operation at high temperatures, which assembly comprises a gas-tight body made of a solid ceramic electrolyte capable of conducting oxygen ions, and at least one layer of an electron-conducting material in contact with the electrolyte and deposited thereon, wherein said layer of electron-conducting material is a compact layer having a thickness of at least 1 micron and at most 200 microns and made of a mixture containing from 20 to 80% by volume of indium oxide In₂ O₃ doped with tin oxide, the remainder being a ceramic material capable of conducting oxygen ions at the cell operating temperature and which is a mixed oxide solid solution, crystallized in the cubic system, consisting essentially of zirconium oxide ZrO₂ and at least one oxide stabilizing the cubic phase of zirconium oxide, said layer being covered by a compact surface layer having a thickness of at least 1 micron and at most 10 microns of ceramic material capable of conducting electrons and oxygen ions and which is a mixed oxide solid solution crystallized in the cubic system, consisting essentially of (1) zirconium oxide ZrO₂, (2) at least one oxide stabilizing the cubic phase of zirconium oxide and (3) uranium oxide UO₂.

2. An electrolyte-cathode assembly as claimed in claim 1 wherein the solid electrolyte has the same composition as the ceramic material which is capable of conducting oxygen ions.

3. An electrolyte-cathode assembly as claimed in claim 1 wherein the ceramic material which is capable of conducting oxygen ions is also capable of conducting electrons.

4. An electrolyte-cathode assembly as claimed in claim 3 wherein the ceramic material is a mixed oxide, in the crystallized state in the cubic system, based on zirconium oxide ZrO₂ and containing at least one oxide stabilizing the cubic phase of zirconium oxide and uranium oxide UO₂.

5. An electrolyte-cathode assembly as claimed in claim 4 wherein the mixed oxide contains at least 78 mol % and at most 86 mol % of zirconium oxide;

at least 8 mole % and at most 12 mol % of ytterbium oxide Yb₂ O₃ and at least 4 mol % and at most 12 mol % of uranium oxide.

6. An electrolyte-cathode assembly as claimed in claim 1 wherein the solid solution contains at least 78 mol % and at most 86 mol % of zirconium oxide;

at least 8 mol % and at most 12 mol % of ytterbium oxide Yb₂ O₃ and at least 4 mol % and at most 12 mol % of uranium oxide.