Mestastable ceramic fuel cell and method of making same

• US 20050244693A1
• Filed: 04/30/2004
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Nano Cell Systems Inc.
• Original Assignee: Nano Cell Systems Inc.
• Inventors: Kear, Bernard H., Strutt, Peter R.
• Granted Patent: US 8,334,079 B2
• Time in Patent Office: Days
• US Class Current: 429/480
• CPC Class Codes: H01M 2004/8684 Negative electrodes
• CPC Class Codes: H01M 2004/8689 Positive electrodes
• CPC Class Codes: H01M 4/8621 containing only metallic or ceramic material, e.g. made by sintering or sputtering
• CPC Class Codes: H01M 4/8652 as mixture
• CPC Class Codes: H01M 4/886 Powder spraying, e.g. wet or dry powder spraying, plasma spraying
• CPC Class Codes: H01M 4/8878 Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
• CPC Class Codes: H01M 4/9025 Oxides specially used in fuel cell operating at high temperature, e.g. SOFC
• CPC Class Codes: H01M 4/9033 Complex oxides, optionally doped, of the type M1MeO3, M1 being an alkaline earth metal or a rare earth, Me being a metal, e.g. perovskites
• CPC Class Codes: H01M 4/9066 of metal-ceramic composites or mixtures, e.g. cermets
• CPC Class Codes: H01M 8/1016 characterised by the electrolyte material H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1253 the electrolyte containing zirconium oxide
• CPC Class Codes: H01M 8/1286 Fuel cells applied on a support, e.g. miniature fuel cells deposited on silica supports
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A solid oxide fuel cell has anode, cathode and electrolyte layers each formed essentially of a multi-oxide ceramic material and having a far-from-equilibrium, metastable structure selected from the group consisting of nanocrystalline, nanocomposite and amorphous. The electrolyte layer has a matrix of the ceramic material, and is impervious and serves as a fast oxygen ion conductor. The electrolyte layer has a matrix of the ceramic material and a dopant dispersed therein in an amount substantially greater than its equilibrium solubility in the ceramic matrix. The anode layer includes a continuous surface area metallic phase in which electron conduction is provided by the metallic phase and the multi-oxide ceramic matrix provides ionic conduction.

Claims

1. A solid oxide fuel cell having anode, cathode and electrolyte layers each formed essentially of a multi-oxide ceramic material, each of said layers having a far-from-equilibrium, metastable structure selected from the group consisting of nanocrystalline, nanocomposite and amorphous, said electrolyte layer having a matrix of said ceramic material, said electrolyte layer being impervious and serving as a fast oxygen ion conductor.

2. A solid oxide fuel cell in accordance with claim 1 wherein the multi-oxide ceramic material of said electrolyte layer is yttria-stabilized zirconia, and wherein the matrix has dispersed therein at least one dopant.

3. A solid oxide fuel cell in accordance with claim 1 wherein said electrolyte layer has a matrix of said ceramic material and a dopant dispersed therein in an amount substantially greater than its equilibrium solubility in said ceramic matrix.

4. A solid oxide fuel cell in accordance with claim 3 wherein said structure of said electrolyte layer is amorphous.

5. A solid oxide fuel cell in accordance with claim 3 wherein said structure of such electrolyte layer is nanocrystalline.

6. A solid oxide fuel cell in accordance with claim 3 wherein said structure of such electrolyte layer minimizes (i) vacancy-vacancy, (ii) vacancy dopant, and (iii) dopant-dopant ordering to minimize restriction of oxygen ion mobility.

7. A solid oxide fuel cell in accordance with claim 6 wherein said dopant introduces elastic strain to counteract electrostatically-induced ordering.

8. A solid oxide fuel cell in accordance with claim 1 wherein said anode layer is porous.

9. A solid oxide fuel cell in accordance with claim 1 wherein said anode layer includes a continuous surface area metallic phase in which electron conduction is provided by said metallic phase and said multi-oxide ceramic matrix provides ionic conduction.

10. A solid oxide fuel cell in accordance with claim 9 wherein said structure of said metallic phase is nanocrystalline.

11. A solid oxide fuel cell in accordance with claim 8 wherein said structure of said multi-oxide ceramic matrix is nanocrystalline.

12. A solid oxide fuel cell in accordance with claim 9 wherein said structure of said multi-oxide ceramic matrix is amorphous.

13. A solid oxide fuel cell in accordance with claim 8 wherein said cathode layer is porous and comprises a multi-oxide ceramic material which provides mixed ionic and electron conduction.

14. A solid oxide fuel cell in accordance with claim 13 wherein said porous cathode layer is a composite structure in which one multi-oxide continuous ceramic phase provides electron conduction and another multi-oxide continuous ceramic phase provides ionic conduction.

15. A solid oxide fuel cell in accordance with claim 1 wherein said electrolyte layer has a graded interface with said anode and cathode layers.

16. A solid oxide fuel cell in accordance with claim 1 wherein both of said anode and cathode layers are porous to permit diffusion.

17. A solid oxide fuel cell in accordance with claim 16 wherein the porosity is nano-porosity.

18. In a method of making a solid oxide fuel cell, the steps comprising:

(a) plasma spraying onto a substrate a fully molten multi-oxide ceramic material; and

(b) instantaneously quenching said molten ceramic material to form a layer of a far-from-equilibrium, metastable structure selected from the group consisting of nanocrystalline, nanocomposite and amorphous.

19. The method of making a solid oxide fuel cell in accordance with claim 18 wherein said multi-oxide ceramic material provides a conductive electrolyte layer.

20. The method of making a solid oxide fuel cell in accordance with claim 19 wherein said multi-oxide ceramic material of said electrolyte layer contains at least one dopant dispersed therein and in an amount substantially greater than its equilibrium solubility in the ceramic matrix.

21. The method of making a solid oxide fuel cell in accordance with claim 18 wherein said dopant is a mixture of an oxide of at least one of the lanthanide group elements (Ce, Tb and Er) and at least one other oxide selected from the group consisting of Y₂O₃, Sc₂O₃, B₂O₃, Al₂O₃, Ga₂O₃, In₂O₃, BeO, MgO, CaO, SrO, BaO.

22. The method of making a solid oxide fuel cell in accordance with claim 18 including the further steps of plasma spraying onto said first mentioned layer a second fully molten multi-oxide ceramic material and instantaneously quenching the sprayed molten material to form an electrolyte layer which is a far-from-equilibrium, metastable structure selected from the group consisting of nanocrystalline, nano-composite and amorphous.

23. The method of making a solid oxide fuel cell in accordance with claim 18 wherein said first mentioned ceramic material contains a metallic component to produce an anode layer including a high surface area metallic phase in which electron conduction is provided in said metallic phase and said ceramic matrix provides ionic conduction.

24. The method of making a solid oxide fuel cell in accordance with claim 18 wherein the interface between said electrolyte and anode layers is graded.

25. The method of making a solid oxide fuel cell in accordance with claim 22 wherein said first mentioned layer is selected from the group consisting of a cathode layer and an anode layer, and including the additional steps of spraying onto said second mentioned layer a third fully molten multi-oxide ceramic material and instantaneously quenching the sprayed material to form a third layer which is the other of said group consisting of a cathode layer, and an anode layer which is a far-from-equilibrium, metastable structure selected from the group consisting of nanocrystalline, nano-composite and amorphous.