Electrode-supported solid state electrochemical cell
View Patent ↗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.
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.