Electrode-supported solid state electrochemical cell

• US 7,416,802 B2
• Filed: 05/22/2001
• Issued: 08/26/2008
• Est. Priority Date: 05/22/2000
• Status: Expired due to Term

• Current Assignee: Acumentrics SOFC Corporation (Acumentrics, Inc.)
• Original Assignee: Acumentrics Corporation (Acumentrics, Inc.)
• Inventors: Brown, Michael, Murray, Tracy, Sammes, Nigel, Ziegler, Warren
• Primary Examiner(s): Ryan; Patrick
• Assistant Examiner(s): MARTIN, ANGELA J
• Application Number:
  US09/864,070
• Publication Number:
  US 20020028367A1
• Time in Patent Office: 2,653 Days
• Field of Search: 429/31, 429/44, 429/30, 429/33, 204/260, 204/424, 264/563, 427/115
• US Class Current: 429/466
• CPC Class Codes: G01N 27/419 Measuring voltages or currents with a combination of oxygen pumping cells and oxygen concentration cells
• CPC Class Codes: H01M 2004/8684 Negative electrodes
• CPC Class Codes: H01M 2008/1293 Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 2300/0077 based on zirconium oxide
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/8626 characterised by the form
• CPC Class Codes: H01M 4/8642 Gradient in composition
• CPC Class Codes: H01M 4/8652 as mixture
• CPC Class Codes: H01M 4/8657 layered
• CPC Class Codes: H01M 4/8864 Extrusion
• CPC Class Codes: H01M 4/8875 Methods for shaping the electrode into free-standing bodies, like sheets, films or grids, e.g. moulding, hot-pressing, casting without support, extrusion without support
• CPC Class Codes: H01M 4/8885 Sintering or firing
• CPC Class Codes: H01M 4/9016 Oxides, hydroxides or oxygenated metallic salts
• 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 4/9041 Metals or alloys H01M4/92 takes precedence
• CPC Class Codes: H01M 4/9066 of metal-ceramic composites or mixtures, e.g. cermets
• CPC Class Codes: H01M 8/1231 with both reactants being gaseous or vaporised
• CPC Class Codes: H01M 8/1246 the electrolyte consisting of oxides
• 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 process for manufacturing a solid oxide fuel cell comprises, in one embodiment according to the invention: forming a plastic mass comprising a mixture of an electrolyte substance and an electrochemically active substance; extruding the plastic mass through a die to form an extruded tube; and sintering the extruded tube to form a tubular anode capable of supporting the solid oxide fuel cell. The process may further comprise, after sintering the extruded tube, layering an electrolyte onto the tubular anode; and, after layering the electrolyte, layering a cathode onto the electrolyte.

In a further related embodiment, the process further comprises co-extruding more than one anode layer to form the tubular anode. Each of the anode layers may comprise a ratio of electrochemically active substance to electrolyte substance, with such ratios being higher for layers that are layered further from a surface of the anode that contacts a fuel gas than for layers that are layered closer to the fuel gas.

Anode-supported tubular solid oxide fuel cells, which may be formed by such processes, are also disclosed. Additionally, electrode-supported oxygen pumps and oxygen sensors, and methods of manufacturing them, are disclosed.

Claims

1. A tubular solid oxide fuel cell comprising:

a sintered tubular anode comprising an electrochemically active metallic substance and an electrolyte substance without a distinct pore forming substance, the electrochemically active metallic substance consisting essentially of reduced metal oxide;

an electrolyte disposed on a surface of the tubular anode; and

a cathode disposed on the electrolyte, wherein a thickness of the anode comprises over 50% of a total thickness of the anode, the electrolyte, and the cathode.

2. A fuel cell according to claim 1, wherein the anode is formed from a mixture of stabilized zirconia and nickel oxide.

3. A fuel cell according to claim 2, wherein the electrolyte comprises stabilized zirconia.

4. A fuel cell according to claim 1, wherein the anode comprises more than one anode layer, each layer having a different composition.

5. A fuel cell according to claim 4, wherein each of the anode layers comprises a ratio of electrochemically active substance to electrolyte substance, and wherein such ratios are higher for layers that are layered further from a surface of the anode that contacts a fuel gas than for layers that are layered closer to the fuel gas.

6. A fuel cell according to claim 5, wherein the electrochemically active substance is nickel and the electrolyte substance is stabilized zirconia.

7. A fuel cell according to claim 5, wherein there are two anode layers.

8. A fuel cell according to claim 4, wherein the more than one anode layers comprise a thicker support layer and a thinner active layer, the support layer being in contact with a fuel gas.

9. A fuel cell according to claim 8, wherein the support layer comprises a higher ratio of stabilized zirconia to nickel, and wherein the active layer comprises a lower such ratio.

10. A fuel cell according to claim 8, wherein the support layer comprises from 0% to 50% nickel by volume.

11. A fuel cell according to claim 8, wherein the active layer comprises from 40% to 45% nickel by volume.

12. A fuel cell according to claim 8, wherein the active layer comprises an embedded current-collecting wire.

13. A fuel cell according to claim 8, wherein the support layer comprises aluminum oxide.

14. A fuel cell according to claim 4, wherein the anode is formed by co-extruding more than one anode layer to form the tubular anode.