초록 ▼

The present invention provides a method for conveniently manufacturing a solid oxide fuel cell (SOFC) at a cost that is less than five-hundred dollars per kilowatt of electricity. The method comprises forming an electrode layer and depositing an electrolyte material on the surface of the electrode.

The present invention provides a method for conveniently manufacturing a solid oxide fuel cell (SOFC) at a cost that is less than five-hundred dollars per kilowatt of electricity. The method comprises forming an electrode layer and depositing an electrolyte material on the surface of the electrode. The formed structure is an electrode-electrolyte bi-layer. A second electrode is deposited onto this bi-layer to form a multilayer fuel cell structure comprising an electrolyte positioned between two electrodes. This multilayer structure is then heated and fired in a single thermal cycle to remove any binder materials and sinter, respectively, the fuel cell. This thermal cycle can be performed in a furnace having one or more chambers. The chamber(s) preferably contains a variable or multiple frequency microwave source for heating the cell and removing binder materials in the electrolyte and electrode structures. The chamber(s) also preferably include a convection and/or radiation source for sintering the fuel cell. In addition, the method of the invention harmonizes and minimizes the deviation among the thermophysical properties of the electrolyte and electrode structures. This harmonization reduces and minimizes the temperature gradient within the cell such that the structure can be uniformly heated and fired during the thermal cycle. The multilayer structure is also unlikely to distort and fracture by minimizing the temperature gradient in the cell. An SOFC can also be manufactured by the present method in an order of magnitude less time than standard processes.

대표청구항 ▼

What is claimed is: 1. A method for manufacturing a solid oxide fuel cell, the method comprising the following steps in the following order: forming a first electrode layer, which before firing has a thickness in a range of about 0.5 to 2.0 mm, the first electrode layer having a surface, and drying

What is claimed is: 1. A method for manufacturing a solid oxide fuel cell, the method comprising the following steps in the following order: forming a first electrode layer, which before firing has a thickness in a range of about 0.5 to 2.0 mm, the first electrode layer having a surface, and drying the first electrode layer; forming an electrolyte layer by screen printing a powder slurry on the surface of the first electrode layer, and drying the electrolyte layer; forming a second electrode layer on a surface of the electrolyte layer, and drying the second electrode layer, wherein the layers comprise a multilayer electrochemical structure; thermally processing the multilayer structure in a single thermal cycle that includes: heating the multilayer structure in a first portion of the single thermal cycle to a temperature and time sufficient to substantially remove moisture; heating the multilayer structure in a second portion of the single thermal cycle to a temperature and time sufficient to substantially remove binder; heating the multilayer structure in a third portion of the single thermal cycle to a temperature and time sufficient to substantially remove carbon residue; and firing the multilayer structure in a fourth portion of the single thermal cycle at a temperature and time sufficient to substantially sinter each layer and to form a solid electrolyte layer. 2. The method of claim 1, the method further comprising: depositing a slurry to form each layer, the slurry comprising binder, dispersant, solvent, plasticizer and composite solids; and drying the deposited slurry. 3. The method of claim 1, wherein energy for heating to remove the binder and other materials is provided by a variable or multiple frequency microwave source. 4. The method of claim 1, wherein firing is performed by convection heating, radiation heating or combinations thereof. 5. The method of claim 1, wherein sintering occurs at temperatures higher than about 1000�� C. 6. The method of claim 1, wherein the heating step is provided by microwave energy. 7. The method of claim 1, wherein first electrode layer is operable to be an anode. 8. The method of claim 7, wherein the first electrode layer after firing is porous. 9. The method of claim 7, wherein the first electrode layer comprises a ceramic composite, the ceramic composite selected from a group consisting of nickel and yttria-stabilized zirconium oxide, nickel and gadolinium oxide doped cerium oxide, nickel and samarium oxide doped cerium oxide, cobalt and yttria-stabilized zirconium oxide, cobalt and gadolinium oxide doped cerium oxide and combinations thereof. 10. The method of claim 1, wherein the second electrode layer is operable to be a cathode. 11. The method of claim 10, wherein the second electrode layer after firing is porous. 12. The method of claim 11, wherein the second electrode layer before firing has a thickness in a range of about 50 to 150 μm. 13. The method of claim 10, wherein the second electrode layer comprises a strontium doped lanthanum manganite-yttria-stabilized zirconium oxide ceramic composite. 14. The method of claim 1, wherein the fired electrolyte layer is a dense solid. 15. The method of claim 14, wherein the electrolyte layer has a thickness before firing in a range of about 5 to 1000 μm. 16. The method of claim 14, wherein the electrolyte layer comprises a conductor, the conductor selected from a group consisting of yttria-stabilized zirconium oxide, ceria-gadolinium oxide, strontium, magnesium lanthanum gallate, rare earth metal doped cerium oxide and combinations thereof. 17. The method of claim 1, the method further comprising: measuring the defined thickness of the dried first layer to compare with a required thickness; providing an additional layer of electrochemically active material onto the dried first layer wherein the additional layer comprises binder, dispersant, solvent, plasticizer and composite solids; drying the additional layer; measuring the defined thickness of the layers to compare with the required thickness; and repeating the providing and drying steps until the defined thickness and the required thickness are about equal. 18. The method of claim 1, the method further comprising: measuring the defined thickness of the dried electrolyte material to compare with a required thickness; providing an additional material onto the dried electrolyte material wherein the additional material comprises binder, dispersant, solvent, plasticizer and composite solids; drying the additional material; measuring the defined thickness of the materials to compare with the required thickness; and repeating the providing and dying steps until the defined thickness and the required thickness are about equal. 19. The method of claim 1, the method further comprising: measuring the defined thickness of the dried second layer to compare with a required thickness; providing an additional layer of electrochemically active material onto the dried second layer wherein the additional layer comprises binder, dispersant, solvent, plasticizer and composite solids; drying the additional layer; measuring the defined thickness to compare with the required thickness; and repeating the providing and dying steps until the defined thickness and the required thickness are about equal. 20. The method of claim 1, further comprising: disposing an interconnect onto a surface of the multilayer electrochemical structure; and repeating the steps of forming a multilayer structure to form one or more additional multilayer structures, wherein the interconnect substantially separates the multilayer structures. 21. The method of claim 1, wherein: the step of forming the electrolyte layer comprises forming an electrolyte layer having a thickness before firing in the range of about 5 to 1000 μm; and the step of forming the second electrode layer comprises forming a ceramic composite material layer having a thickness before firing in the range of about 50 to 150 μm. 22. The method of claim 1, wherein the step of forming at least one of the layers comprises depositing two or more sublayers of composite material to provide a defined thickness. 23. The method of claim 1, wherein energy for heating is provided by a microwave source. 24. The method of claim 1, wherein the second electrode layer is formed by screen printing on the surface of the electrolyte layer. 25. The method of claim 1, wherein: the step of heating in a first portion of the single thermal cycle is provided at a temperature range of about 125 150�� C.; the step of heating in a second portion of the single thermal cycle is provided in a temperature range of about 275 375�� C.; the step of heating in a third portion of the single thermal cycle is provided in a temperature range of about 500 600�� C.; and the step of firing in a fourth portion of the single thermal cycle is provided at a temperature range of about 1000 1500�� C. 26. The method of claim 1, wherein: the step of forming a first electrode layer includes forming a first porous electrode layer; and the step of forming an electrolyte layer includes forming a dense electrolyte layer, the first porous electrode layer and dense electrolyte layer comprising a bi-layer. 27. The method of claim 1, further comprising: disposing an interconnect layer onto the surface of the second electrode layer; and repeating the three forming steps to form another multilayer structure. 28. The method of claim 1, further comprising: repeating the three forming steps to provide an intended number of cells, each having a first electrode layer, an electrolyte layer and a second electrode layer; disposing an interconnect between each threelayer cell; and disposing an interconnect on the outer surface of the first electrode layer of one cell and the outer surface of the second electrode layer of another cell. 29. The method of claim 1, further comprising: after the step of forming a first electrode layer, the step of removing the first electrode layer from a surface on which the first electrode layer is formed. 30. The method of claim 29, further comprising trimming the first electrode layer to a desired size. 31. The method of claim 1, further comprising: disposing an interconnect layer onto the surface of the second electrode layer, and repeating the three forming steps to form another multilayer structure, wherein the interconnect layer includes passages for guiding flow of fuel or oxidant there through to adjacent electrode layers. 32. A method for manufacturing a solid oxide fuel cell, the method comprising the following steps in the following order: providing a first electrode layer of electrochemically active material on a substrate, the first electrode layer having a surface opposite the substrate; removing the first electrode layer from the substrate; depositing a layer of electrolyte material by screen printing a powder slurry including solid electrolyte particles on the surface of the first electrode layer; depositing a second electrode layer of electrochemically active material by screen printing on a surface of the electrolyte material, wherein the electrolyte material is disposed between the electrode layers to comprise a multilayer electrochemical structure; and thermally processing the multilayer structure in a single thermal cycle that includes: heating the multilayer structure in a first portion of the single thermal cycle to substantially remove moisture; heating the multilayer structure in a second portion of the single thermal cycle to substantially remove binder; heating the multilayer structure in a third portion of the single thermal cycle to substantially remove carbon residue; firing the multilayer structure in a fourth portion of the single thermal cycle to substantially sinter each layer and to form a solid electrolyte layer; repeating the three forming steps to provide an intended number of cells, each having a first electrode layer, an electrolyte layer and a second electrode layer; disposing an interconnect layer between a surface of the second electrode layer and a surface of the first electrode layer of adjacent cells; and disposing an interconnect layer on the outer surface of the first electrode layer of one cell and an interconnect layer on the outer surface of the second electrode layer of another cell. 33. The method of claim 32, wherein the first electrode layer is formed by tape casting.