WO2017014069A1 - 燃料電池用電解質層-アノード複合部材およびその製造方法 - Google Patents
燃料電池用電解質層-アノード複合部材およびその製造方法 Download PDFInfo
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- WO2017014069A1 WO2017014069A1 PCT/JP2016/070259 JP2016070259W WO2017014069A1 WO 2017014069 A1 WO2017014069 A1 WO 2017014069A1 JP 2016070259 W JP2016070259 W JP 2016070259W WO 2017014069 A1 WO2017014069 A1 WO 2017014069A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
- H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
- H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
- H01M8/1253—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides the electrolyte containing zirconium oxide
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/8663—Selection of inactive substances as ingredients for catalytic active masses, e.g. binders, fillers
- H01M4/8668—Binders
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8825—Methods for deposition of the catalytic active composition
- H01M4/8828—Coating with slurry or ink
- H01M4/8835—Screen printing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
- H01M4/9025—Oxides specially used in fuel cell operating at high temperature, e.g. SOFC
- H01M4/9033—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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
- H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
- H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
- H01M8/126—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides the electrolyte containing cerium oxide
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
- H01M2004/8684—Negative electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
- H01M2004/8689—Positive electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
- H01M2008/1293—Fuel cells with solid oxide electrolytes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0068—Solid electrolytes inorganic
- H01M2300/0071—Oxides
- H01M2300/0074—Ion conductive at high temperature
- H01M2300/0077—Ion conductive at high temperature based on zirconium oxide
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to an electrolyte layer-anode composite member including a solid electrolyte having ion conductivity and a method for manufacturing the same.
- the anode In a fuel cell (SOFC) including a solid electrolyte having negative ion conductivity, the anode includes a nickel (Ni) component as a catalyst and a solid electrolyte (metal oxide).
- Ni nickel
- metal oxide metal oxide
- Such an anode is generally formed by sintering a material including a solid electrolyte and nickel oxide (NiO).
- the composite member of the solid electrolyte layer and the anode is prepared by, for example, forming a precursor of an anode using a material containing a solid electrolyte and NiO, and then applying the solid electrolyte to the surface. It is produced by sintering.
- the treatment of reducing NiO to Ni when the treatment of reducing NiO to Ni is performed, the function of Ni is enhanced, and at the same time, the anode is made porous so that the fuel gas can permeate.
- the reduction treatment is performed in a state where the electrolyte layer-anode composite member is incorporated in the fuel cell.
- anode including a mixed powder of BCY powder and NiO powder as an anode material is formed.
- a thin layer of BCY powder which is a material for the solid electrolyte layer, is applied to the anode, and then co-sintered at a temperature at which both are densified (usually about 1300 to 1500 ° C.), so that a layer containing BCY, BCY and NiO
- An electrolyte layer-anode composite member comprising a layer containing Next, the electrolyte layer-anode composite member is incorporated in a fuel cell and subjected to reduction treatment in an atmosphere of a reducing gas such as hydrogen.
- the electrolyte layer-anode composite member may be warped during these steps. If the electrolyte layer-anode composite member is warped, the power generation performance may be degraded, or if the warp is excessive, the electrolyte layer-anode composite member may be damaged.
- Patent Document 1 teaches controlling the coefficient of thermal expansion of the solid electrolyte.
- Patent Document 2 teaches that the cell dimensional change rate when NiO is reduced is controlled.
- One aspect of the present invention includes a solid electrolyte layer including a metal oxide M1 having ion conductivity, a first anode layer including a metal oxide M2 having ion conductivity and nickel oxide, the solid electrolyte layer, and the first electrolyte layer.
- a second anode layer that includes a metal oxide M3 having ion conductivity and nickel oxide interposed between the first anode layer and a volume-based content ratio Cn1 of the nickel oxide in the first anode layer;
- the present invention relates to a fuel cell electrolyte layer-anode composite member in which the nickel oxide volume-based content Cn2 in the second anode layer satisfies a relationship of Cn1 ⁇ Cn2.
- Another aspect of the present invention is a material for a solid electrolyte layer containing a metal oxide M1 having ion conductivity, an anode material A containing a metal oxide M2 having ion conductivity and a nickel compound N1, and ion conduction.
- a first step of preparing an anode material B including a metal oxide M3 having a property and a nickel compound N2, a precursor layer of a first anode layer including the anode material A, and the anode material B A second step of forming a laminate in which the precursor layer of the second anode layer and the precursor layer of the solid electrolyte layer containing the material for the solid electrolyte layer are laminated in this order; and firing the laminate, A third step of forming the first anode layer, the second anode layer, and the solid electrolyte layer, and a volume-based content ratio Cn1 of the nickel oxide in the first anode layer;
- the present invention relates to a method for producing an electrolyte layer-anode composite member for a fuel cell, wherein the volume-based content ratio Cn2 of the nickel oxide in the second anode layer satisfies a relationship of Cn1 ⁇ Cn2.
- Still another aspect of the present invention includes the electrolyte layer-anode composite member, the cathode, an oxidant flow path for supplying an oxidant to the cathode, and a fuel flow path for supplying fuel to the anode. And a fuel cell.
- FIG. 1 is a cross-sectional view schematically showing an electrolyte layer-anode composite member according to an embodiment of the present invention.
- FIG. 4 is a cross-sectional view schematically showing an electrolyte layer-anode composite member according to another embodiment of the present invention.
- FIG. 4 is a cross-sectional view schematically showing an electrolyte layer-anode composite member according to another embodiment of the present invention.
- 1 is a cross-sectional view schematically showing a fuel cell according to an embodiment of the present invention.
- FIG. 6 is a cross-sectional view schematically showing a conventional electrolyte layer-anode composite member.
- Factors of warpage of the electrolyte layer-anode composite member include (i) the difference in thermal expansion coefficient between the solid electrolyte layer and the anode during cooling after co-sintering, and (ii) Both the difference in shrinkage between the solid electrolyte layer and the anode in the reduction treatment of NiO can be mentioned. Therefore, the methods of Patent Documents 1 and 2 have room for improvement with respect to the effect of suppressing the warpage of the electrolyte layer-anode composite member. [Effects of the present disclosure]
- the electrolyte layer-anode composite member of the present invention includes a solid electrolyte layer containing a metal oxide M1 having ion conductivity, a first anode layer containing a metal oxide M2 having ion conductivity and nickel oxide, A second anode layer interposed between the solid electrolyte layer and the first anode layer and containing metal oxide M3 having ion conductivity and nickel oxide.
- the volume-based content rate Cn1 of the nickel oxide in the first anode layer and the volume-based content rate Cn2 of the nickel oxide in the second anode layer satisfy the relationship of Cn1 ⁇ Cn2.
- the Cn1 is preferably 40 to 80% by volume, and the Cn2 is preferably 50 to 90% by volume. This further suppresses warpage in the composite member manufacturing step and the reduction treatment step, and improves power generation performance when the composite member is incorporated in a fuel cell.
- the ratio of the total thickness of the first anode layer T1 and the thickness T2 of the second anode layer to the thickness Te: (T1 + T2 ) / Te is preferably 10 or more. This is because the mechanical strength of the electrolyte layer-anode composite member is improved and the resistance to ion conduction in the solid electrolyte layer is reduced.
- the metal oxide M1, the metal oxide M2, and the metal oxide M3 preferably have a perovskite crystal structure represented by ABO 3 . This is because of high proton conductivity. At this time, it is preferable that the A 1 site contains at least one group 2 element, and the B site contains at least one kind of cerium and zirconium and a rare earth element.
- the metal oxide M1, the metal oxide M2, and the metal oxide M3 are represented by the formula (1): BaCe 1-a Y a O 3- ⁇ (where 0 ⁇ a ⁇ 0.5 , ⁇ is oxygen deficiency), formula (2): BaZr 1-b Y b O 3- ⁇ (where 0 ⁇ b ⁇ 0.5, ⁇ is oxygen deficiency), and formula (3 ): BaZr 1-cd Ce c Y d O 3- ⁇ (where 0 ⁇ c ⁇ 1, 0 ⁇ d ⁇ 0.5, ⁇ is the amount of oxygen deficiency). It is preferable that there is at least one. This is because proton conductivity is further improved.
- the metal oxide M1, the metal oxide M2, and the metal oxide M3 are zirconium dioxide doped with at least one selected from the group consisting of calcium, scandium, and yttrium (stabilized zirconia). May be included. This is because the above compound has high oxygen ion conductivity and easily suppresses deterioration of each layer due to phase transformation.
- At least a part of the nickel oxide contained in at least one of the anode layers may be contained in each anode layer as metallic nickel by reduction treatment. Thereby, when incorporated in a fuel cell, the function as an electrolyte-anode composite member is exhibited.
- the method for producing an electrolyte layer-anode composite member for a fuel cell according to the present invention includes a material for a solid electrolyte layer containing a metal oxide M1 having ion conductivity, a metal oxide M2 having ion conductivity, and a nickel compound.
- a precursor layer, a precursor layer of the second anode layer containing the anode material B, and a precursor layer of the solid electrolyte layer containing the solid electrolyte layer material form a laminate in which the precursor layers are laminated in this order.
- the volume-based content rate Cn1 of the nickel oxide in the first anode layer and the volume-based content rate Cn2 of the nickel oxide in the second anode layer satisfy the relationship of Cn1 ⁇ Cn2.
- the manufacturing method further includes a fourth step of reducing at least a part of the nickel oxide contained in the first anode layer and the second anode layer. This is because the function of Ni as a catalyst is enhanced. At the same time, each anode layer is made porous so that fuel gas can permeate.
- the fuel cell of the present invention comprises the above electrolyte layer-anode composite member and a cathode, an oxidant flow path for supplying an oxidant to the cathode, and a fuel for supplying the anode The fuel flow path is provided.
- This fuel cell is excellent in power generation performance and durability.
- the linear expansion coefficient of nickel oxide (NiO) serving as a catalyst precursor is usually larger than that of a solid electrolyte (for example, a metal oxide such as BCY or yttria stabilized zirconia (YSZ)) used for SOFC.
- a solid electrolyte for example, a metal oxide such as BCY or yttria stabilized zirconia (YSZ)
- the linear expansion coefficient of NiO is approximately 14 ⁇ 10 ⁇ 6 / K
- the linear expansion coefficient of the metal oxide is approximately 8 to 12 ⁇ 10 ⁇ 6 / K. Therefore, the thermal expansion coefficient of the anode containing these is usually larger than that of the solid electrolyte layer containing only the same or different solid electrolyte. Therefore, due to the difference in the coefficient of thermal expansion in the composite member production process (mainly cooling after co-sintering) between the anode and the solid electrolyte layer (factor (i)), the anode side is directed inward. Warping occurs.
- a method of increasing the thickness ratio of the solid electrolyte layer and the anode by thinning the solid electrolyte layer examples include a method of increasing the thickness ratio and improving the rigidity of the anode and a method of reducing the difference in thermal expansion coefficient between the solid electrolyte layer and the anode.
- thinning the solid electrolyte layer there is a limit to thinning the solid electrolyte layer, and when the anode layer is thickened, the fuel gas transport resistance increases and the volume and mass increase.
- the ratio of NiO in the anode is reduced, as a matter of course, the ratio of Ni contained in the anode after reduction is reduced. Therefore, the electrical conductivity in the anode is lowered, and the energy loss when taking out the electrical energy is increased. Furthermore, at the interface between the anode and the solid electrolyte layer, the amount of Ni that is a catalyst for decomposing hydrogen is small, so the performance of decomposing fuel gas (such as H 2 ) into protons (H + ) is reduced, and power generation performance is reduced. To do.
- Fuel gas permeation performance is required for the anode.
- the fuel gas passes through a void formed in the anode as NiO is reduced to Ni.
- the ratio of NiO in the anode is small, as a result, the porosity formed in the anode after the reduction treatment is reduced.
- the probability that the air gaps are combined decreases, and the diffusion resistance of the fuel gas at the anode increases. Therefore, power generation performance is reduced. It is also conceivable to allow the fuel gas to permeate through the gap introduced by using a foaming agent or the like when the anode is manufactured, instead of the gap.
- the factor (ii) causing the difference in shrinkage between the solid electrolyte layer and the anode in the reduction treatment step is a decrease in the volume of the anode mainly caused by the reduction of NiO to Ni.
- the solid electrolyte layer not containing NiO shows little change in volume. Therefore, the warp of the composite member in the reduction treatment process occurs in the same direction as the warp caused by the difference in linear expansion coefficient in the manufacturing process.
- the solid electrolyte layer may expand due to hydrogen solid solution in the solid electrolyte or release of compressive stress. In this case, the difference in shrinkage between the solid electrolyte layer and the anode further increases. In order to suppress this warpage, it is only necessary to suppress the volume reduction of the anode.
- the warping factors (i) and (ii) can be eliminated.
- the power generation performance is degraded. In other words, there is a trade-off between the elimination of warpage and the power generation performance.
- the volume reduction rate of the anode and the NiO content in the anode are not in a linear relationship.
- the linear expansion coefficient of the composite material is different from being in a substantially linear relationship with the mixing ratio in consideration of the linear expansion coefficient and the elastic coefficient of each material.
- the metal oxide powder and the NiO powder are strongly bonded (sintered), respectively. That is, a skeleton containing each powder is formed on the anode by sintering the powders.
- the content rate of NiO is small, the amount of shrinkage of the skeleton containing NiO is small even when reduction treatment is performed.
- the skeleton including the metal oxide powder having a large relative content is firmly formed. Therefore, the shape of the skeleton including the metal oxide is easily maintained. That is, although the void is formed by the reduction from NiO to Ni, the apparent volume of the anode is hardly reduced.
- the content rate of NiO exceeds a certain threshold value, the skeleton including the metal oxide is not sufficiently formed, and the skeleton including NiO tends to contract greatly with the reduction treatment. Therefore, the skeleton including the metal oxide is dragged by the contraction of the skeleton including NiO, and it is difficult to maintain the shape. As a result, the outer shape of the anode contracts and the apparent volume is greatly reduced.
- the volume reduction amount of the anode rapidly increases.
- the rigidity of the skeleton is also affected by the type of powder used, the particle size, and the like. In other words, the volume reduction rate of the anode and the NiO content of the anode are not in a linear proportion, so it is very difficult to find a NiO content that can achieve both the elimination of warpage and the power generation performance. .
- the anode 1 is warped by using a plurality of anode layers (first anode layer 1a and second anode layer 1b) having different NiO contents. It has been found that it is possible to achieve both the elimination of power generation and the power generation performance. In other words, by combining a plurality of anode layers having different NiO contents, that is, linear expansion coefficients, as the anode 1, it is possible to achieve both elimination of warpage and excellent power generation performance.
- the NiO content in each anode layer the NiO content in the second anode layer 1b interposed between the solid electrolyte layer 2 and the first anode layer 1a is maximized. Therefore, the linear expansion coefficient ⁇ a of the first anode layer 1a and the linear expansion coefficient ⁇ b of the second anode layer 1b satisfy the relationship ⁇ a ⁇ b. Further, the linear expansion coefficient ⁇ e of the solid electrolyte layer and ⁇ a and ⁇ b satisfy the relationship of ⁇ e ⁇ a ⁇ b.
- the second anode layer 1b having a large linear expansion coefficient is interposed between the solid electrolyte layer 2 and the first anode layer 1a.
- the thickness of the second anode layer 1b is not particularly limited.
- the thickness T2 of the second anode layer 1b is smaller than the thickness T1 of the first anode layer 1a (case 1.
- the linear expansion The solid electrolyte layer 2 having a small coefficient and the second anode layer 1b having a large linear expansion coefficient can be regarded as one composite layer.
- the thermal contraction rate of the composite layer and the first anode layer 1a can be made comparable when cooling after co-sintering or cooling after reduction treatment. . Therefore, the curvature of a composite member is suppressed. Further, in the above case, since the ratio of the first anode layer 1a having the smallest NiO content in the composite member is relatively large, there is an advantage that the contraction rate in the main surface direction of the entire composite member tends to be small.
- the thickness of each layer is set to 10 ⁇ m, 20 ⁇ m, and 0.5 mm in the composite member with the layer 1a
- an approximate value of the linear expansion coefficient of the solid electrolyte layer obtained by taking into account the content of each metal oxide) Value (hereinafter the same)
- ⁇ e, approximate value ⁇ b of the linear expansion coefficient of the second anode layer 1b, and approximate value ⁇ a of the linear expansion coefficient of the first anode layer 1a are calculated.
- the linear expansion coefficient of each material BCY: 11 ⁇ 10 ⁇ 6 / K and NiO: 14 ⁇ 10 ⁇ 6 / K, respectively.
- the solid electrolyte layer 2 and the second anode layer 1b are regarded as one layer, and it is considered that a composite layer (thickness 30 ⁇ m) of the solid electrolyte layer 2 and the second anode layer 1b is laminated on the first anode layer 1a.
- the thickness T2 of the second anode layer 1b may be substantially the same as the thickness T1 of the first anode layer 1a (case 2. For example, when the thickness T2 is greater than 1/10 of the thickness T1 and less than 10 times) ). As the case 2, for example, the thickness of both the first and second anode layers is 0.5 mm, and the solid electrolyte layer 2 having a thickness of 10 ⁇ m is formed on the surface of the second anode layer 1b. .
- a laminate (anode laminate) having only the first and second anode layers is assumed.
- the anode laminate is warped such that the second anode layer 1b side is inward.
- the linear expansion coefficient of the second anode layer 1b is larger than the linear expansion coefficient of the first anode layer 1a.
- the moment M see below
- the difference in heat shrinkage between the solid electrolyte layer 2 and the second anode layer 1b is larger than the difference in heat shrinkage between the second anode layer 1b and the first anode layer 1a.
- the difference in NiO content (linear expansion coefficient) between the two anode layers may be small.
- the effect of disposing the solid electrolyte layer 2 on the second anode layer 1b side is high. Since this case can reduce the difference in NiO content between the two anode layers, it has the advantage that the matching at the bonding interface between the two anode layers can be improved.
- high consistency means that the local stress at the interface is small.
- the first anode having a smaller linear expansion coefficient than the second anode layer 1b.
- the layer 1a By disposing the layer 1a on the surface of the second anode layer 1b that does not face the solid electrolyte layer 2, warping of the composite member can be suppressed. This is because the moment M of the entire composite material is canceled by disposing layers having a small linear expansion coefficient on both sides of the second anode layer 1b having a large thickness. In this case, compressive stress is generated on both surfaces of the second anode layer 1b. Therefore, there is an advantage that the progress of cracks from the surface of the second anode layer 1b where defects tend to exist is suppressed, and the breakage of the composite material itself is suppressed.
- the shrinkage (factor (ii)) of the anode 1 accompanying the volume reduction in the reduction treatment increases rapidly when the NiO content exceeds a certain threshold (usually 50 to 70% by volume). Tend. Therefore, as in the case of the factor (i), it is difficult to calculate and discuss an approximate value of the volume change (in this case, the volume reduction rate).
- a certain threshold usually 50 to 70% by volume.
- setting the relationship between the NiO content Cn1 in the first anode layer 1a and the NiO content Cn2 in the second anode layer 1b to be Cn1 ⁇ Cn2 is also effective in suppressing warpage due to the reduction treatment.
- the second anode layer 1b having a higher NiO content is opposed to the solid electrolyte layer 2
- H 2 (fuel gas) that has permeated through the first anode layer 1a is separated from the solid electrolyte layer by the catalytic action of Ni. 2 is efficiently decomposed into protons at the interface between the second anode layer 1b and the second anode layer 1b. Therefore, the power generation performance is improved. That is, by making the anode 1 as described above, it is possible to achieve both the elimination of warpage and the power generation performance.
- the NiO content Cn1 in the first anode layer 1a is not particularly limited, but is preferably 40 to 80% by volume, and 45 to 70% by volume in consideration of the balance between warpage suppression and power generation efficiency. Is more preferable.
- the NiO content Cn2 in the second anode layer 1b is not particularly limited as long as it is higher than Cn1. Among these, from the same viewpoint as Cn1, the content Cn2 is preferably 50 to 90% by volume, and more preferably 55 to 80% by volume.
- the NiO content Cn in the whole anode is, for example, about 40 to 80% by volume.
- the soot contents Cn1 and Cn2 can be set in consideration of the total shrinkage of each anode layer. That is, the content rates Cn1 and Cn2 may be changed according to the thicknesses of the first anode layer 1a and the second anode layer 1b. At this time, the thickness Te of the solid electrolyte layer 2 is not particularly limited.
- NiO content rates Cn1 and Cn2 satisfy Cn1 ⁇ Cn2
- the content rate Cn1r of Ni (or the sum of NiO and Ni) in the first anode layer 1a after the reduction treatment and the second anode layer 1b The content ratio Cn2r of Ni (or the sum of NiO and Ni) also satisfies Cn1r ⁇ Cn2r.
- the composite member after the reduction treatment satisfies Cn1r ⁇ Cn2r
- the composite member before reduction satisfies Cn1 ⁇ Cn2.
- the volume-based content of NiO or Ni in the anode 1 can be calculated by taking an SEM photograph of the cross section of the anode 1. Specifically, first, in the SEM photograph of the cross section of the anode 1, a region R containing 100 or more NiO or Ni particles is determined. This region R includes metal oxide particles, NiO or Ni particles, and voids. Assuming that the depth of the region R (the length in the normal direction of the SEM photograph) is sufficiently smaller than the diameter of NiO or Ni particles, the total of the regions occupied by all NiO or Ni particles is divided by the area of the region R. Thus, the volume content of NiO or Ni is determined.
- the volume content of NiO or Ni may be calculated as described above for a plurality of (for example, five) regions R of the same anode 1, and the average value thereof may be used as the volume content of NiO or Ni.
- the volume content of NiO or Ni can also be calculated by emission spectroscopic analysis (ICP-AES) for high frequency inductively coupled plasma.
- ICP-AES emission spectroscopic analysis
- the powder obtained by scraping the first anode layer 1a or the second anode layer 1b is decomposed or melted by acid decomposition or the like and used as a sample.
- warp change index i the rate of change of the warp amount due to the difference in linear expansion coefficient
- the warp is caused by the factor (i) because the moment M (around the center point C when the thickness direction of the composite material is the Z axis and the center point C of the thickness T of the entire composite material is the coordinate (Zc). This is because the moment) changes. Therefore, the change rate of the moment M is set as a warp change index i.
- the moment M can be regarded as the sum of moments of each layer calculated in consideration of the difference between the linear expansion coefficient of the reference layer and the linear expansion coefficient of each layer.
- the warpage change index i is obtained by dividing the moment M by the moment M 0 of the composite member 100 (see FIG. 3) manufactured by only one anode layer (here, the first anode layer 1a) in which the anode 1 is homogeneous. By doing so, it can be calculated.
- the reference layer is the first anode layer 1a.
- the moment generated by the solid electrolyte layer 2 is expressed as K (Ze ⁇ Zc) ( ⁇ e ⁇ a)), and the moment generated by the first anode layer 1a is expressed as K (Za ⁇ Zc) ( ⁇ a ⁇ a). Represented. Since the moment generated by the first anode layer 1a is 0 (zero), the moment M 0 is expressed as K (Ze ⁇ Zc) ( ⁇ e ⁇ a).
- K is a constant determined by the thickness T of the composite material
- Za is the coordinate of the center point of the thickness T1 of the first anode layer 1a
- Ze is the coordinate of the center point of the thickness Te of the solid electrolyte layer 2
- ⁇ e represents the linear expansion coefficient of the solid electrolyte layer 2
- ⁇ a represents the linear expansion coefficient of the first anode layer 1a.
- the moment M (Me + Mb), and the warpage change index i is represented by (Me + Mb) / M 0 .
- the warpage change index is positive, it is estimated that warpage occurs so that the solid electrolyte layer 2 side is convex, and when negative, warpage occurs so as to be concave.
- each linear expansion coefficient ⁇ in the moment calculation formula may be replaced with the NiO content (Cn1 or Cn2) of each layer.
- the thermal expansion coefficient ⁇ e of the solid electrolyte 2 is 0 (zero).
- the warpage change index i calculated in this way preferably has an absolute value of 0.5 or less.
- the effect of suppressing the warp due to the factor (ii) is to use the outer diameter change amount of each anode layer accompanying the reduction treatment instead of the part for obtaining the difference between the linear expansion coefficient of the reference layer and the linear expansion coefficient of each layer.
- it can be expressed as a warp change index ii.
- the sum of the warpage change index i and the warpage change index ii preferably has an absolute value of 0.5 or less.
- FIGS. 1A to 1C are cross-sectional views schematically showing electrolyte layer-anode composite members according to different embodiments.
- the soot composite member 10 includes a first anode layer 1a, a second anode layer 1b, and a solid electrolyte layer 2.
- the second anode layer 1b is interposed between the solid electrolyte layer 2 and the first anode layer 1a, and the first anode layer 1a, the second anode layer 1b, and the solid electrolyte layer 2 are integrated by firing. Yes.
- the solid electrolyte layer 2 includes a metal oxide M1 having ion conductivity.
- the metal oxide M1 has proton conductivity
- the solid electrolyte layer 2 moves protons generated at the anode 1 to the cathode 3 (see FIG. 2).
- the metal oxide M1 has oxygen ion conductivity
- the solid electrolyte layer 2 moves oxygen ions generated at the cathode 3 to the anode 1.
- the thickness Te of the solid electrolyte layer 2 is preferably 3 to 50 ⁇ m and more preferably 5 to 30 ⁇ m from the viewpoint of achieving both ion conductivity and gas barrier performance.
- the ratio of the thickness Te to the total thickness of the thickness T1 of the first anode layer 1a and the thickness T2 of the second anode layer 1b described later: (T1 + T2) / Te is preferably 10 or more. More preferably.
- the solid electrolyte layer 2 may be a laminate of a plurality of solid electrolyte layers.
- the type of the metal oxide M1 included in each solid electrolyte layer may be the same or different.
- the same kind of metal oxide only needs to contain the same kind of metal element, and these atomic composition ratios may be different (hereinafter the same).
- a plurality of metal oxides containing barium (Ba), zirconium (Zr), and yttrium (Y) and having different atomic composition ratios of Zr and Y are the same type.
- Metal oxide M1 As the metal oxide M1, for example, a known material used as a solid electrolyte of a fuel cell can be used. Among these, as the metal oxide M1 having proton conductivity, a compound having a perovskite crystal structure represented by A 1 B 1 O 3 (hereinafter, perovskite oxide P1) is preferably exemplified. A 1 B 1 O 3 also includes the crystal structure of A 1 B 1 O 3- ⁇ ( ⁇ is the amount of oxygen deficiency). The perovskite crystal structure is a crystal structure similar to CaTiO 3 . Note that an element having an ionic radius larger than that of the B 1 site enters the A 1 site. Moreover, the compound Z1 containing zirconium dioxide is preferably exemplified as the metal oxide M1 having oxygen ion conductivity.
- the metal element entering the A 1 site is not particularly limited, but may be a group 2 element such as Ba, calcium (Ca), strontium (Sr), or the like. These can be used alone or in combination of two or more. Among these, from the viewpoint of proton conductivity, Ba is preferably contained at the A 1 site.
- the metal element that enters the B 1 site examples include cerium (Ce), Zr, and Y.
- the B 1 site preferably contains at least one of Zr and Ce.
- a part of the B 1 site is substituted with a trivalent rare earth element other than cerium. Oxygen defects are generated by such a dopant, and the perovskite oxide P1 exhibits proton conductivity.
- trivalent rare earth elements (dopants) other than cerium examples include yttrium (Y), scandium (Sc), neodymium (Nd), samarium (Sm), gadolinium (Gd), holmium (Ho), erbium (Er), and thulium. (Tm), ytterbium (Yb), lutetium (Lu) and the like.
- Y or an element having an ionic radius smaller than Y occupies a part of the B 1 site. Examples of the element include Sc, Ho, Er, Tm, Yb, and Lu.
- the B 1 site may contain an element that acts as a dopant other than rare earth elements (for example, indium (In)).
- the formula (1-1) BaCe 1-a1 Y a1 O 3- ⁇ (0 ⁇ a1 ⁇ 0.5, particularly excellent in proton conductivity and high power generation performance) (BCY), formula (2-1): BaZr 1-b1 Y b1 O 3- ⁇ (0 ⁇ b1 ⁇ 0.5, BZY), a formula (3-1) of these solid solutions: BaZr 1-c1-d1 A compound represented by Ce c1 Y d1 O 3- ⁇ (0 ⁇ c1 ⁇ 1, 0 ⁇ d1 ⁇ 0.5, BZCY) is preferable.
- These perovskite oxides P1 may be used singly or in combination of two or more.
- a part of Y occupying the B 1 site may be substituted with other elements (for example, other lanthanoid elements), and a part of Ba occupying the A 1 site may be other two group elements. (Sr, Ca, etc.) may be substituted.
- the compound Z1 which is another preferred compound of the metal oxide M1, preferably contains at least one element selected from the group consisting of Ca, Sc and Y, which together with zirconium dioxide, substitutes and dissolves Zr. Thereby, compound Z1 expresses oxygen ion conductivity.
- Preferred examples of the compound Z1 include yttria-stabilized zirconia (ZrO 2 —Y 2 O 3 , YSZ) in terms of oxygen ion conductivity and cost.
- the solid electrolyte layer 2 may contain components other than the metal oxide M1, but its content is preferably small. For example, it is preferable that 99 mass% or more of the solid electrolyte layer 2 is the metal oxide M1.
- Components other than the metal oxide M1 are not particularly limited, and examples of the solid electrolyte include known compounds (including compounds having no ion conductivity).
- the anode 1 includes at least a first anode layer 1a and a second anode layer 1b.
- Each of the first anode layer 1a and the second anode layer 1b includes a metal oxide (M2 or M3) having ion conductivity and NiO.
- M2 or M3 metal oxide having ion conductivity and NiO.
- the NiO content Cn1 in the first anode layer 1a and the NiO content Cn2 in the second anode layer 1b satisfy Cn1 ⁇ Cn2.
- the content rate Cn of each NiO is calculated
- the anode 1 is made porous by reduction treatment.
- the porous anode 1 oxidizes a fuel such as hydrogen introduced from a flow path to be described later to release protons and electrons (fuel oxidation reaction), or oxidizes the fuel to generate H
- a reaction is performed to produce 2 O (CO 2 when the fuel is a hydrocarbon such as CH 4 ).
- the thickness T1 of the first anode layer 1a and the thickness T2 of the second anode layer 1b are not particularly limited.
- the total thickness of the anode 1 including the first anode layer 1a and the second anode layer 1b is preferably 0.3 to 5 mm, more preferably 0.5 to 4 mm.
- the ratio of the thicknesses T1 and T2 is not particularly limited, and may be appropriately set in consideration of the balance between warpage suppression and power generation performance and the NiO content of each layer.
- the case 1 for example, when the thickness T2 is one digit or more (10 times or more) smaller than the thickness T1, see FIG. 1A
- the case 2 for example, the thickness T2 is 1/10 of the thickness T1.
- the case 3 for example, when the thickness T2 is one digit or more (10 times or more) larger than the thickness T1; see FIG. 1C) is assumed.
- Anode 1 may include three or more anode layers.
- the first anode layer 1a and the second anode layer 1b may each be formed of a plurality of anode layers, or a third anode layer (not shown) other than the first anode layer 1a and the second anode layer 1b. May be provided.
- the third anode layer may be laminated on the surface of the first anode layer 1a opposite to the surface facing the second anode layer 1b. Furthermore, the third anode layer is laminated between the first anode layer 1a and the second anode layer 1b or between the second anode layer 1b and the solid electrolyte layer 2 as long as the effect of the present embodiment is not hindered. May be.
- the third anode layer may contain a metal oxide having ion conductivity and NiO.
- the composite member has gas decomposition performance, and this composite member can be used in a gas decomposition apparatus.
- a gas containing gas such as ammonia, methane (CH 4 ), propane or the like that decomposes to generate hydrogen
- a decomposition reaction of these gases occurs at the anode 1
- hydrogen is generated.
- the composite member has gas decomposition performance, and this composite member can be used in a gas decomposition apparatus.
- a metal oxide having oxygen ion conductivity may be used for each layer constituting the composite member. preferable.
- the anode 1 may contain a catalyst having a function of decomposing the gas.
- the catalyst having a function of decomposing gas such as ammonia include compounds containing at least one catalyst component selected from the group consisting of Fe, Co, Ti, Mo, W, Mn, Ru, and Cu.
- the metal oxide M2 contained in the first anode layer 1a has ionic conductivity.
- Examples of such a metal oxide M2 include metal oxides similar to those exemplified for the metal oxide M1.
- preferred examples of the metal oxide M2 include a compound having a perovskite type crystal structure represented by A 2 B 2 O 3 (hereinafter, perovskite type oxide P2) and a compound Z2 containing zirconium dioxide.
- the A 2 B 2 O 3 also includes a crystal structure of A 2 B 2 O 3- ⁇ ( ⁇ is the amount of oxygen deficiency). An element having an ionic radius larger than that of the B 2 site enters the A 2 site.
- the formula (1-2) BaCe 1-a2 Y a2 O 3- ⁇ (0 ⁇ a2 ⁇ 0.5, in that it has excellent proton conductivity and exhibits high power generation performance.
- BCY formula (2-2): BaZr 1-b2 Y b2 O 3- ⁇ (0 ⁇ b2 ⁇ 0.5, BZY), a formula (3-2) of these solid solutions: BaZr 1-c2-d2
- a compound represented by Ce c2 Y d2 O 3- ⁇ (0 ⁇ c2 ⁇ 1, 0 ⁇ d2 ⁇ 0.5, BZCY) is preferable.
- These perovskite oxides P2 may be used singly or in combination of two or more.
- a part of Y occupying the B 2 site may be substituted with other elements (for example, other lanthanoid elements), and a part of Ba occupying the A 2 site may be other two group elements. (Sr, Ca, etc.) may be substituted.
- examples of the compound Z2 containing zirconium dioxide include the same metal oxides exemplified as the compound Z1.
- YSZ can be preferably exemplified in terms of oxygen ion conductivity and cost.
- Metal oxide M3 The metal oxide M3 contained in the second anode layer 1b also has ionic conductivity.
- Examples of such metal oxide M3 include the same compounds as metal oxides M1 and M2.
- preferred examples of the metal oxide M3 include a compound having a perovskite crystal structure represented by A 3 B 3 O 3 (hereinafter referred to as a perovskite oxide P3) and a compound Z3 containing zirconium dioxide. Is done.
- a 3 B 3 O 3 includes a crystal structure of A 3 B 3 O 3- ⁇ ( ⁇ is the amount of oxygen deficiency). An element having a larger ion radius than the B 3 site enters the A 3 site.
- Examples of the element entering the A 3 site and the B 3 site of the perovskite oxide P3 include the same elements as those entering the A 1 (A 2 ) site and the B 1 (B 2 ) site.
- Examples of the compound Z3 containing zirconium dioxide include the same metal oxides exemplified as the compound Z1 (Z2). Among these, YSZ can be preferably exemplified in terms of oxygen ion conductivity and cost.
- the types of metal oxides M2 and M3 may be the same or different. Especially, it is preferable that the types of the metal oxides M2 and M3 are the same from the viewpoint of matching at the interface of each anode layer, suppression of warpage, and suppression of mutual diffusion of metal elements.
- all of the metal oxides M1, M2, and M3 contain the same type of metal oxide from the viewpoint of easily aligning the behavior when firing each layer and maintaining consistency at the interface of each layer.
- contraction amount at the cooling process after a co-sintering and a reduction process can be controlled and suppressed.
- the electrolyte layer-anode composite member includes, for example, a solid electrolyte layer material including a metal oxide M1 having ion conductivity, an anode material A including a metal oxide M2 having ion conductivity and a nickel compound N1, and ions.
- a third step of forming a second anode layer and a solid electrolyte layer In the third step, the nickel compound N1 and the nickel compound N2 (except NiO) are oxidized to produce NiO.
- volume-based content ratio Cn1 of NiO contained in the obtained first anode layer and the volume-based content ratio Cn2 of NiO contained in the second anode layer satisfy the relationship of Cn1 ⁇ Cn2.
- a solid electrolyte material is a material for forming the solid electrolyte layer 2 and includes a metal oxide M1 having ion conductivity.
- the anode material A is a material for forming the first anode layer 1a, and includes a metal oxide M2 having ion conductivity and a nickel compound N1.
- the anode material B is a material for forming the second anode layer 1b, and includes a metal oxide M3 having ion conductivity and a nickel compound N2.
- nickel compounds N1 and N2 examples include hydroxides, salts (such as inorganic acid salts such as carbonates), halides, and the like.
- nickel oxides such as NiO are preferably used in that the volume change until the third step is small and the shrinkage behavior can be easily controlled.
- a nickel compound may be used individually by 1 type, and may be used in combination of 2 or more type.
- the nickel compounds N1 and N2 may be the same or different.
- the nickel compound N1 content Cna in the soot anode material A may be in a range such that the NiO content Cn1 in the first anode layer 1a after firing is, for example, 40 to 80% by volume.
- the content Cnb of the nickel compound N2 in the anode material B may be in a range such that the NiO content Cn2 in the second anode layer 1b after firing is, for example, 50 to 90% by volume.
- Each material preferably contains a binder from the viewpoint of moldability.
- a binder known materials used for the production of ceramic materials, for example, cellulose derivatives such as ethyl cellulose (cellulose ether and the like), vinyl acetate resins (including saponified vinyl acetate resins such as provinyl alcohol), Examples thereof include polymer binders such as acrylic resins; waxes such as paraffin wax.
- the amount of the binder contained in each anode material is, for example, 1 to 15 parts by mass (particularly with respect to 100 parts by mass of the total amount of metal oxide and nickel compound) when each anode material is subjected to press molding. Is 3 to 10 parts by mass), and in other cases, for example, 1 to 20 parts by mass (particularly 1.5 to 15 parts by mass).
- the amount of the binder contained in the solid electrolyte material is, for example, 1 to 20 parts by mass (particularly 1.5 to 15 parts by mass) with respect to 100 parts by mass of the metal oxide.
- Each material may contain a dispersion medium such as water and an organic solvent (for example, hydrocarbon such as toluene; alcohol such as ethanol and isopropanol; carbitol such as butyl carbitol acetate) as necessary.
- an organic solvent for example, hydrocarbon such as toluene; alcohol such as ethanol and isopropanol; carbitol such as butyl carbitol acetate
- Each material may contain various additives such as a surfactant and a peptizer (polycarboxylic acid or the like) as necessary.
- the precursor layer of the first anode layer 1a containing the anode material A, the precursor layer of the second anode layer 1b containing the anode material B, and the precursor of the solid electrolyte layer 2 containing the solid electrolyte layer material In the second step, the precursor layer of the first anode layer 1a containing the anode material A, the precursor layer of the second anode layer 1b containing the anode material B, and the precursor of the solid electrolyte layer 2 containing the solid electrolyte layer material.
- the body layers form a stacked body that is stacked in this order.
- each precursor layer is not particularly limited, and may be appropriately selected depending on the desired thickness of each layer.
- each material can be formed by press molding or tape molding.
- each material can be formed by an existing method such as screen printing, spray coating, spin coating, dip coating, or the like.
- a laminate may be formed by combining these methods.
- the precursor layer of the solid electrolyte layer 2 is usually formed by screen printing, spray coating, spin coating, dip coating, or the like.
- the anode material A is first formed into a predetermined shape by press molding.
- the predetermined shape is, for example, a pellet shape, a plate shape, or a sheet shape.
- the anode material A may be granulated to form a granulated product. If necessary, the obtained granulated product may be pulverized and the pulverized product may be subjected to molding.
- the precursor layer of the second anode layer 1b is laminated on the surface of the molded precursor layer of the first anode layer 1a.
- the precursor layer of the second anode layer 1b is formed by applying the anode material B to the surface of the precursor layer of the first anode layer 1a by, for example, screen printing, spray coating, spin coating, dip coating, or the like.
- the solid electrolyte material is applied to the surface of the molded precursor layer of the second anode layer 1b by the same method to form a precursor layer of the solid electrolyte layer. In this way, a laminate is obtained.
- each anode material powder is filled in layers in a press molding machine, and then press molded to form a precursor layer for the first anode layer 1a and a precursor for the second anode layer 1b.
- the body layer may be formed in one step.
- the anode material B is formed into a predetermined shape by press molding or the like, and then the solid electrolyte material and the anode material A are formed into a precursor layer of the molded second anode layer 1b.
- the precursor layer of the first anode layer 1a and the precursor layer of the second anode layer 1b are respectively formed by tape molding and laminated, and then the solid electrolyte material is formed on the surface of the precursor layer of the second anode layer 1b. May be applied.
- a step of temporarily firing the precursor layer of the second anode layer 1b may be performed.
- the temporary firing may be performed at a temperature lower than the temperature at which the anode material B is sintered (for example, 900 to 1100 ° C.). By performing the preliminary firing, the solid electrolyte material is easily applied.
- the obtained laminate is fired. Firing is performed by heating the obtained laminate to, for example, 1200 to 1700 ° C. in an oxygen-containing atmosphere.
- the oxygen content in the firing atmosphere is not particularly limited. Firing may be performed, for example, in an air atmosphere (oxygen content: about 20% by volume) or in pure oxygen (oxygen content: 100% by volume). Firing can be performed under normal pressure or under pressure.
- resin components such as a binder contained in each material may be removed. That is, the firing may be performed after the laminate is heated to a relatively low temperature of about 500 to 700 ° C. in the atmosphere to remove the resin component contained in each material.
- the composite member 10 in which the first anode layer 1a, the second anode layer 1b, and the solid electrolyte layer 3 are integrally formed is obtained.
- a reduction process (fourth step) may be performed to reduce at least part of NiO contained in the formed first anode layer 1a and NiO contained in the second anode layer 1b.
- the reduction treatment is usually performed by heating the composite member 10 to 500 to 800 ° C. in a reducing gas atmosphere.
- the reduction treatment can be performed under normal pressure or under pressure.
- a typical reducing gas is hydrogen.
- hydrocarbons such as methane and propane may be used as the reducing gas in addition to hydrogen.
- the reduction process may be performed before or after the composite member 10 is incorporated into the fuel cell 20.
- FIG. 2 schematically shows a cross section of the structure of the fuel cell 20.
- the fuel cell 20 includes a cell including the composite member 10 (10A) and the cathode 3, an oxidant flow path 33 for supplying an oxidant to the cathode 3, and a fuel flow path 13 for supplying fuel to the anode.
- the composite member 10A shown in FIG. 1A is used as the composite member, but the present invention is not limited to this.
- the composite member 10 Since the composite member 10 has the above-described configuration, warping of the composite member 10 is suppressed during temperature rise and cooling when the fuel cell 20 is operated. Therefore, the deterioration of the cell due to thermal fatigue is suppressed, and the durability of the fuel cell 20 is improved.
- the composite member 10 may or may not be reduced.
- the oxidant flow path 33 has an oxidant inlet into which the oxidant flows and an oxidant discharge port through which water generated by the reaction, unused oxidant, and the like are discharged (both not shown).
- a gas containing oxygen is exemplified.
- the fuel flow path 13 includes a fuel gas inlet through which fuel gas flows and a fuel gas outlet through which unused fuel and H 2 O generated by reaction (CO 2 when the fuel is a hydrocarbon such as CH 4 ) are discharged. (Both not shown).
- the fuel cell 20 can operate in a temperature range of 800 ° C. or less, and when the metal oxide M1 has proton conductivity, 700 It is possible to operate in the temperature range below °C.
- the operating temperature is preferably in the middle temperature range of about 400 to 600 ° C.
- the cathode 3 can adsorb oxygen molecules, dissociate them and ionize them, and has a porous structure.
- a reaction oxygen reduction reaction
- Oxide ions are generated by dissociation of an oxidant (oxygen) introduced from an oxide flow path, which will be described later.
- a known material used as a cathode of a fuel cell or a gas decomposition apparatus can be used.
- a perovskite oxide is preferable.
- lanthanum strontium cobalt ferrite La 1-e Sr e Co 1-f Fe f O 3- ⁇ , 0 ⁇ e ⁇ 1,0 ⁇ f ⁇ 1, ⁇ is the oxygen deficiency amount
- Lanthanum strontium manganite LSM, La 1-g Sr g MnO 3- ⁇ , 0 ⁇ g ⁇ 1, ⁇ is oxygen deficiency
- LSC Lanthanum strontium cobaltite
- LSC La 1-h Sr h CoO 3- ⁇ , 0 ⁇ h ⁇ 1, ⁇ is the oxygen deficiency amount
- SSC samarium strontium cobaltite
- SSC Sm 1-i Sr i CoO 3- ⁇ , 0 ⁇ i ⁇ 1, ⁇ is the oxygen
- the soot cathode 3 may contain a catalyst such as Ag. This is because the reaction between the proton and the oxidizing agent is promoted.
- the cathode 3 can be formed by mixing the catalyst and the material and sintering the mixture.
- the thickness of the cathode 3 is not particularly limited, but may be about 10 ⁇ m to 30 ⁇ m.
- the soot oxidizing agent channel 33 may be formed in, for example, the cathode side separator 32 disposed outside the cathode.
- the fuel flow path 13 may be formed in the anode side separator 12 arrange
- the fuel cell 10 is configured by stacking a plurality of cell structures, for example, the cell, the cathode-side separator 32, and the anode-side separator 12 are stacked as a unit.
- the plurality of cells may be connected in series by, for example, a separator having gas flow paths (oxidant flow paths and fuel flow paths) on both sides.
- the material of the heel separator examples include heat-resistant alloys such as stainless steel, nickel-base alloy, and chromium-base alloy in terms of conductivity and heat resistance. Of these, stainless steel is preferable because it is inexpensive. When the operating temperature of the fuel cell 20 is about 400 to 600 ° C., stainless steel can be used as the separator material.
- the fuel cell 20 may further include a current collector.
- the fuel cell 20 includes a cathode-side current collector 31 disposed between the cathode and the cathode-side separator 32, and an anode-side current collector 11 disposed between the anode and the anode-side separator 12. You may have.
- the cathode current collector 31 functions to supply the cathode 3 while diffusing the oxidant gas introduced from the oxidant flow path 33.
- the anode-side current collector 11 functions to supply the anode 1 while diffusing the fuel gas introduced from the fuel flow path 13. Therefore, each current collector is preferably a breathable structure.
- each current collector examples include metal porous bodies containing platinum, silver, silver alloys, Ni, Ni alloys, etc., metal meshes, punching metals, expanded metals, and the like.
- a metal porous body is preferable at the point of lightweight property or air permeability.
- a porous metal body having a three-dimensional network structure is preferable.
- the three-dimensional network structure refers to a structure in which rod-like or fibrous metals constituting a metal porous body are three-dimensionally connected to form a network.
- a sponge-like structure or a nonwoven fabric-like structure can be mentioned.
- the metal porous body can be formed, for example, by coating a resin porous body having continuous voids with the metal as described above. When the internal resin is removed after the metal coating process, a cavity is formed inside the skeleton of the metal porous body, and the metal becomes hollow.
- a commercially available metal porous body having such a structure “Celmet” (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. can be used.
- Example 1 A composite member was produced by the following procedure. (1) Preparation of each material As a metal oxide, BCY powder which was a solid solution of BaCeO 3 and Y 2 O 3 and had a perovskite crystal structure was prepared. The ratio (atomic composition ratio) between Ce and Y in BCY was 80:20, and the chemical formula of BCY powder was estimated to be BaCe 0.8 Y 0.2 O 2.9 .
- a mixed powder A containing the obtained mixture (80% by volume) and a binder (acrylic resin, 20% by volume) was prepared.
- the BCY powder was mixed with 70% by volume of NiO (catalyst raw material), pulverized and kneaded by a ball mill (70% by volume), and a binder (cellulose resin, 30 volumes). %) was prepared.
- a paste C containing the BCY powder (35% by volume), an organic solvent (butyl carbitol acetate, 40% by volume), and a binder (cellulose resin, 25% by volume) was prepared.
- the composite member A was heated at 600 ° C. for 10 hours in a hydrogen atmosphere to reduce NiO to Ni.
- the Ni content in the second anode layer after the reduction treatment was about 37% by volume, and the Ni content in the first anode layer was also about 32% by volume.
- a composite member having the same configuration as that of the composite member A is prepared except that the outer diameter of the composite member is 25 mm.
- a cell was fabricated using the members. The cell is screen-printed on the surface of the solid electrolyte layer of the composite member with a LSCF paste in which a powder of LSCF (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3- ⁇ ), which is a cathode material, and the organic solvent are mixed. Then, it produced by baking for 2 hours at 1000 degreeC. The thickness of the cathode was 10 ⁇ m.
- Example 2 A composite member B and a fuel cell B were produced and evaluated in the same manner as in Example 1 except that the content of NiO in the first anode layer was 50% by volume. The results are shown in Table 2. The Ni content in the first anode layer after the reduction treatment was about 27% by volume.
- Example 3 A composite member C and a fuel cell C were produced and evaluated in the same manner as in Example 2 except that the thickness of the second anode layer was 30 ⁇ m. The results are shown in Table 2.
- Comparative Example 1 A composite member a and a fuel cell a were produced and evaluated in the same manner as in Example 1 except that the content of NiO in the first anode layer was 70% by volume and the second anode layer was not formed. The results are shown in Table 2.
- Comparative Example 2 >> A composite member b and a fuel cell b were produced and evaluated in the same manner as in Example 1 except that the second anode layer was not formed. The results are shown in Table 2.
- Comparative Example 3 A composite member c and a fuel cell c were produced and evaluated in the same manner as in Example 2 except that the second anode layer was not formed. The results are shown in Table 2.
- Comparative Example 4 >> The composite member d and the fuel cell d were formed in the same manner as in Example 1 except that the NiO content in the first anode layer was 70% by volume and the NiO content in the second anode layer was 50% by volume. Prepared and evaluated. The results are shown in Table 2.
- Composite members A to C had very small warpage and excellent power generation performance.
- the composite members B, C, and a to d were not damaged such as cracks, and the overall shrinkage of the composite member after sintering (before reduction treatment) was about 20 to 22%.
- Example 4 A composite member D and a fuel cell D were prepared and evaluated in the same manner as in Example 1 except that the type of metal oxide, the NiO content and thickness of each anode layer, and the firing temperature were changed.
- the composition of the composite member D is shown in Table 3, and the results are shown in Table 4.
- a BZY powder which is a solid solution of BaZrO 3 and Y 2 O 3 and has a perovskite crystal structure was prepared.
- the ratio (atomic composition ratio) between Zr and Y in BZY was 80:20, and the chemical formula of BZY powder was estimated to be BaZr 0.8 Y 0.2 O 2.9 .
- the firing temperature of the laminate was 1500 ° C.
- the obtained composite member D was not damaged such as cracks, and the overall shrinkage rate of the composite member D after sintering (before reduction treatment) was about 21%.
- Example 5 A composite member E and a fuel cell E were produced and evaluated in the same manner as in Example 4 except that the content of NiO in the second anode layer was 60% by volume. The results are shown in Table 4.
- Comparative Example 5 A composite member e and a fuel cell e were prepared and evaluated in the same manner as in Example 4 except that the content of NiO in the second anode layer was set to 70% by volume and the first anode layer was not formed. The results are shown in Table 4.
- Comparative Example 6 >> A composite member f and a fuel cell f were produced and evaluated in the same manner as in Example 5 except that the first anode layer was not formed. The results are shown in Table 4.
- Composite members D and E showed power generation performance equivalent to that of composite members e and f, and the amount of warpage was kept small.
- the composite members E, e, and f were not damaged such as cracks, and the overall shrinkage rate of the composite member after sintering (before reduction treatment) was about 20 to 22%.
- Example 6 A composite member was produced by the following procedure. (1) Preparation of each material YSZ powder which is a solid solution of ZrO 2 and Y 2 O 3 was prepared as a metal oxide. The ratio (atomic composition ratio) between Zr and Y in YSZ was 90:10.
- a slurry A containing a mixture (55% by volume) obtained in this manner and a binder (PVB resin, 45% by volume) was prepared.
- As anode material B slurry B containing 70% by volume of NiO was prepared in the same manner as described above.
- a slurry C containing the YSZ powder (55% by volume) and a binder (PVB resin, 45% by volume) was prepared.
- the obtained laminate was heated in the atmosphere at 600 ° C. for 1 hour to remove the binder and the organic solvent. Subsequently, firing was performed at 1300 ° C. for 2 hours in an oxygen atmosphere to obtain a composite member F.
- Table 5 shows the configuration of the composite member F. The resulting composite member F was not damaged such as cracks. The volume of the composite member F was contracted by about 23% with respect to the laminate.
- Comparative Example 7 >> A composite member g and a fuel cell g were prepared and evaluated in the same manner as in Example 6 except that the content of NiO in the first anode layer was 70% by volume. The results are shown in Table 6.
- the composite member F exhibited power generation performance equivalent to that of the composite member g, and the amount of warpage was kept small.
- the composite member g was not damaged such as cracks.
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Abstract
Description
本出願は、2015年7月17日出願の日本出願第2015-143012号に基づく優先権を主張し、前記日本出願に記載された全ての記載内容を援用するものである。
[本開示の効果]
[発明の実施形態の説明]
最初に本発明の実施形態の内容を列記して説明する。
(1)本発明の電解質層-アノード複合部材は、イオン伝導性を有する金属酸化物M1を含む固体電解質層と、イオン伝導性を有する金属酸化物M2および酸化ニッケルを含む第1アノード層と、前記固体電解質層と前記第1アノード層との間に介在し、イオン伝導性を有する金属酸化物M3および酸化ニッケルを含む第2アノード層と、を備える。このとき、前記第1アノード層における前記酸化ニッケルの体積基準の含有率Cn1と、前記第2アノード層における前記酸化ニッケルの体積基準の含有率Cn2とは、Cn1<Cn2の関係を満たす。これにより、複合部材を燃料電池に組み込んだ場合の発電性能の低下を抑制しながら、複合部材を作製および還元処理する際の反りを抑制することができる。
これにより、燃料電池に組み込まれた場合に、電解質-アノード複合部材としての機能が発揮される。
このとき、前記第1アノード層における前記酸化ニッケルの体積基準の含有率Cn1と、前記第2アノード層における前記酸化ニッケルの体積基準の含有率Cn2とは、Cn1<Cn2の関係を満たす。この方法により、反りが抑制された電解質層-アノード複合部材を、効率よく製造することができる。
本発明の実施形態を具体的に以下に説明する。なお、本発明は、以下の内容に限定されるものではなく、請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
つまり、アノードには、それぞれの粉末同士の焼結により、各粉末を含む骨格がそれぞれ形成されている。NiOの含有率が小さい場合、還元処理を行っても、NiOを含む骨格の収縮量は小さい。また、相対的な含有率の大きい金属酸化物粉末を含む骨格は、強固に形成されている。そのため、金属酸化物を含む骨格の形状は維持され易い。つまり、NiOからNiへの還元により空隙は形成されるものの、アノードの見かけの体積はほとんど減少しない。
ケース1(図1A参照)の場合、基準となる層は、十分な厚みを有する第1アノード層1aである。すなわち、各層のモーメントは、
Me=K(Ze-Zc)(αe―αa)
Ma=K(Za-Zc)(αa-αa)=0
Mb=K(Zb-Zc)(αb-αa)
と表わされる。ここで、Zbは第2アノード層1bの厚さT2の中心点の座標、αbは第2アノード層1bの線膨張係数を示す。
ケース2(図1B参照)の場合、基準となる層は、第1アノード層1aおよび第2アノード層1bの両層である。そのため、基準となる層の線膨張係数として、第1アノード層および第2アノード層の厚さを考慮した加重平均の熱膨張係数(=αav)を用いる。この場合、各層のモーメントは、
Me=K(Ze-Zc)(αe―αav)
Ma=K(Za-Zc)(αa-αav)
Mb=K(Zb-Zc)(αb-αav)
と表わされる。よって、モーメントM=(Me+Ma+Mb)であり、反り変化指標iは(Me+Ma+Mb)/M0で表わされる。
ケース3(図1C参照)の場合、基準となる層は、十分な厚みを有する第2アノード層1bである。すなわち、各層のモーメントは、
Me=K(Ze-Zc)(αe―αb)
Ma=K(Za-Zc)(αa-αb)
Mb=K(Zb-Zc)(αb-αb)=0
と表わされる。よって、モーメントM=(Me+Ma)であり、反り変化指標iは(Me+Ma)/M0で表わされる。
以下、複合部材の一実施形態について、図1A~1Cを参照しながら説明する。図1A~1Cは、それぞれ異なる実施形態に係る電解質層-アノード複合部材を模式的に示す断面図である。
固体電解質層2は、イオン伝導性を有する金属酸化物M1を含む。金属酸化物M1がプロトン伝導性を有する場合、固体電解質層2は、アノード1で生成されたプロトンをカソード3(図2参照)へと移動させる。金属酸化物M1が酸素イオン伝導性を有する場合、固体電解質層2は、カソード3で生成された酸素イオンをアノード1へと移動させる。
金属酸化物M1としては、例えば、燃料電池の固体電解質として用いられる公知の材料を用いることができる。なかでも、プロトン伝導性を有する金属酸化物M1として、A1B1O3で表わされるペロブスカイト型の結晶構造を有する化合物(以下、ペロブスカイト型酸化物P1)が好ましく例示される。A1B1O3には、A1B1O3-δ(δは酸素欠損量)の結晶構造も含む。ペロブスカイト型の結晶構造とは、CaTiO3に類似の結晶構造である。なお、A1サイトには、B1サイトよりイオン半径の大きな元素が入る。また、酸素イオン伝導性を有する金属酸化物M1として、二酸化ジルコニウムを含む化合物Z1が好ましく例示される。
化合物Z1としては、酸素イオン伝導性とコストの点で、イットリア安定化ジルコニア(ZrO2-Y2O3、YSZ)が好ましく例示できる。
アノード1は、少なくとも第1アノード層1aおよび第2アノード層1bを備える。第1アノード層1aおよび第2アノード層1bはいずれも、イオン伝導性を有する金属酸化物(M2またはM3)およびNiOを含む。第1アノード層1aにおけるNiOの含有率Cn1と、第2アノード層1bにおけるNiOの含有率Cn2とは、Cn1<Cn2を満たす。なお、各NiOの含有率Cnは、上記のように求められる。
第1アノード層1aに含まれる金属酸化物M2は、イオン伝導性を有する。このような金属酸化物M2としては、例えば、金属酸化物M1で例示したものと同様の金属酸化物が例示される。具体的には、金属酸化物M2として、A2B2O3で表わされるペロブスカイト型の結晶構造を有する化合物(以下、ペロブスカイト型酸化物P2)、および、二酸化ジルコニウムを含む化合物Z2が好ましく例示される。A2B2O3には、A2B2O3-δ(δは酸素欠損量)の結晶構造も含む。A2サイトには、B2サイトよりイオン半径の大きな元素が入る。
第2アノード層1bに含まれる金属酸化物M3もまた、イオン伝導性を有する。このような金属酸化物M3としては、金属酸化物M1およびM2と同様の化合物が例示できる。
具体的には、金属酸化物M3としては、A3B3O3で表わされるペロブスカイト型の結晶構造を有する化合物(以下、ペロブスカイト型酸化物P3)、および、二酸化ジルコニウムを含む化合物Z3が好ましく例示される。A3B3O3には、A3B3O3-δ(δは酸素欠損量)の結晶構造も含む。A3サイトには、B3サイトよりイオン半径の大きな元素が入る。
電解質層-アノード複合部材は、例えば、イオン伝導性を有する金属酸化物M1を含む固体電解質層用材料と、イオン伝導性を有する金属酸化物M2およびニッケル化合物N1を含むアノード用材料Aと、イオン伝導性を有する金属酸化物M3およびニッケル化合物N2を含むアノード用材料Bと、を準備する第1工程と、アノード用材料Aを含む第1アノード層の前駆体層、アノード用材料Bを含む第2アノード層の前駆体層および固体電解質層用材料を含む固体電解質層の前駆体層が、この順で積層された積層体を形成する第2工程と、積層体を焼成して、第1アノード層、第2アノード層および固体電解質層を形成する第3工程と、を含む方法により製造される。第3工程において、ニッケル化合物N1およびニッケル化合物N2(NiOを除く)は酸化され、NiOを生じる。このとき、得られる第1アノード層に含まれるNiOの体積基準の含有率Cn1と、第2アノード層に含まれるNiOの体積基準の含有率Cn2とは、Cn1<Cn2の関係を満たす。以下、各工程について詳細に説明する。
第1工程では、固体電解質用材料と、アノード用材料Aと、アノード用材料Bとを準備する。固体電解質用材料は、固体電解質層2を形成するための材料であって、イオン伝導性を有する金属酸化物M1を含む。アノード用材料Aは、第1アノード層1aを形成するための材料であって、イオン伝導性を有する金属酸化物M2およびニッケル化合物N1を含む。アノード用材料Bは、第2アノード層1bを形成するための材料であって、イオン伝導性を有する金属酸化物M3およびニッケル化合物N2を含む。
ニッケル化合物は、一種を単独で用いてもよく、二種以上を組み合わせて用いてもよい。
ニッケル化合物N1およびN2は、同じであっても良いし、異なっていても良い。
第2工程では、アノード用材料Aを含む第1アノード層1aの前駆体層、アノード用材料Bを含む第2アノード層1bの前駆体層および固体電解質層用材料を含む固体電解質層2の前駆体層が、この順で積層された積層体を形成する。
第3工程では、得られた積層体を焼成する。焼成は、得られた積層体を、酸素含有雰囲気下で、例えば1200~1700℃に加熱することにより行われる。焼成の雰囲気中の酸素含有量は、特に限定されない。焼成は、例えば大気雰囲気(酸素含有率:約20体積%)で行っても良いし、純酸素(酸素含有率:100体積%)中で行っても良い。焼成は、常圧下または加圧下で行うことができる。
さらに、形成された第1アノード層1aに含まれるNiOおよび第2アノード層1bに含まれるNiOの少なくとも一部を還元する還元処理(第4工程)を行っても良い。還元処理は、複合部材10を、還元性ガス雰囲気下で、通常、500~800℃に加熱することにより行われる。還元処理は、常圧下または加圧下で行うことができる。還元性ガスとしては、水素が代表的である。複合部材10が、酸素イオン伝導性を有する金属酸化物を含む場合、還元性ガスとして、水素のほかに、例えば、メタン、プロパン等の炭化水素を用いても良い。還元処理は、複合部材10を燃料電池20に組み込む前に行っても良いし、組み込んだ後に行っても良い。
図2に燃料電池20の構造の断面を、模式的に示す。
燃料電池20は、上記複合部材10(10A)およびカソード3を備えるセル、カソード3に酸化剤を供給するための酸化剤流路33、および、アノードに燃料を供給するための燃料流路13を有する。図示例では、複合部材として図1Aに示す複合部材10Aを用いているが、これに限定されない。
下記の手順で複合部材を作製した。
(1)各材料の準備
金属酸化物として、BaCeO3とY2O3との固溶体であり、ペロブスカイト型の結晶構造を持つBCY粉末を準備した。BCY中のCeとYとの比率(原子組成比)は80:20であり、BCY粉末の化学式はBaCe0.8Y0.2O2.9と推定された。
アノード用材料Bとして、上記BCY粉末に、NiO(触媒原料)を70体積%含むように混合し、ボールミルによって粉砕混練して得られた混合物(70体積%)と、バインダ(セルロース樹脂、30体積%)とを含むペーストBを準備した。
固体電解質用材料として、上記BCY粉末(35体積%)と、有機溶媒(ブチルカルビトールアセテート、40体積%)と、バインダ(セルロース樹脂、25体積%)とを含むペーストCを準備した。
混合粉末Aを用い、一軸プレス成形によって、直径140mm、厚み0.8mmの円形シート状成形体を得た。
(3)第2アノード層の前駆体層の形成
形成された成形体の片面に、ペーストBをスクリーン印刷によって塗布した。塗布厚は、約15μmであった。
塗布されたペーストBの表面に、ペーストCをスクリーン印刷によって塗布して、積層体を得た。塗布厚は、約15μmであった。
次いで、得られた積層体を、大気中600℃で1時間加熱して、バインダおよび有機溶媒を除去した。続いて、酸素雰囲気下、1350℃で2時間の焼成を行い、複合部材Aを得た。複合部材Aの構成を表1に示す。得られた複合部材Aにクラック等の破損は見られなかった。複合部材Aの体積は、積層体に対して約21%収縮していた。
続いて、複合部材Aを、水素雰囲気下、600℃で10時間加熱して、NiOをNiに還元した。還元処理後の第2アノード層におけるNi含有率は約37体積%であり、同じく第1アノード層におけるNi含有率は約32体積%であった。
焼結後および還元処理後の反り量と、還元処理後の外径変化量を測定した。反り量は、複合部材Aを、水平面に複合部材の凸部が上になるようにして載置し、水平面と凸部の最も高い地点との最短距離として求めた。外径変化は、上記の状態で、複合部材Aを水平面の法線方向から見た場合の直径を求め、これと、焼結前の複合部材(積層体)の直径とを比較した。結果を表2に示す。
発電性能を評価するため、複合部材の外径が25mmになるようにしたこと以外は、複合部材Aと同じ構成を有する複合部材を作成し、この還元処理前の複合部材を用いてセルを作製した。セルは、複合部材の固体電解質層の表面に、カソードの材料であるLSCF(La0.6Sr0.4Co0.2Fe0.8O3-δ)の粉末と上記有機溶媒とを混合したLSCFペーストをスクリーン印刷し、続いて、1000℃で2時間の焼成を行うことにより作製した。カソードの厚みは10μmであった。
動作温度を600℃として、作製された燃料電池Aのアノードに燃料ガスとして水素を100cm3/分で流し、カソードに空気を300cm3/分で流した時の最大の出力密度を求めた。なお、還元処理はこの工程で実行された。結果を表2に示す。
第1アノード層におけるNiOの含有率を50体積%にしたこと以外は、実施例1と同様にして、複合部材Bおよび燃料電池Bを作製し、評価した。結果を表2に示す。還元処理後の第1アノード層におけるNi含有率は約27体積%であった
第2アノード層の厚みを30μmにしたこと以外は、実施例2と同様にして、複合部材Cおよび燃料電池Cを作製し、評価した。結果を表2に示す。
第1アノード層におけるNiOの含有率を70体積%にし、第2アノード層を形成しなかったこと以外は、実施例1と同様にして、複合部材aおよび燃料電池aを作製し、評価した。結果を表2に示す。
第2アノード層を形成しなかったこと以外は、実施例1と同様にして、複合部材bおよび燃料電池bを作製し、評価した。結果を表2に示す。
第2アノード層を形成しなかったこと以外は、実施例2と同様にして、複合部材cおよび燃料電池cを作製し、評価した。結果を表2に示す。
第1アノード層におけるNiOの含有率を70体積%にし、第2アノード層におけるNiOの含有率を50体積%にしたこと以外は、実施例1と同様にして、複合部材dおよび燃料電池dを作製し、評価した。結果を表2に示す。
金属酸化物の種類、各アノード層のNiO含有率および厚み、焼成温度を変えたこと以外は、実施例1と同様にして、複合部材Dおよび燃料電池Dを作製し、評価した。複合部材Dの構成を表3に示し、結果を表4に示す。
第2アノード層におけるNiOの含有率を60体積%にしたこと以外は、実施例4と同様にして、複合部材Eおよび燃料電池Eを作製し、評価した。結果を表4に示す。
第2アノード層におけるNiOの含有率を70体積%にし、第1アノード層を形成しなかったこと以外は、実施例4と同様にして、複合部材eおよび燃料電池eを作製し、評価した。結果を表4に示す。
第1アノード層を形成しなかったこと以外は、実施例5と同様にして、複合部材fおよび燃料電池fを作製し、評価した。結果を表4に示す。
下記の手順で複合部材を作製した。
(1)各材料の準備
金属酸化物として、ZrO2とY2O3との固溶体であるYSZ粉末を準備した。YSZ中のZrとYとの比率(原子組成比)は90:10であった。
アノード用材料Bとして、上記と同様にして、NiOを70体積%含むスラリーBを準備した。
固体電解質用材料として、上記YSZ粉末(55体積%)と、バインダ(PVB系樹脂、45体積%)とを含むスラリーCを準備した。
スラリーAを用い、ドクターブレード法によって、厚み0.5mmのシート状成形体Aを得た。同様に、スラリーBを用いた厚み0.5mmのシート状成形体B、および、スラリーCを用いた厚み12μmのシート状成形体Cを得た。
これらのシート状成形体をシート状成形体A、B、Cの順に重ねてラミネートし、全体の厚みが約1.0mmの積層シートを得た。この積層シートを直径140mmの円形に打ち抜き、積層体を得た。
実施例1と同様にして、還元処理および反り評価を行った。別途、実施例1と同様にして燃料電池を作製し、動作温度800℃における発電性能を評価した。結果を表6に示す。
第1アノード層におけるNiOの含有率を70体積%にしたこと以外は、実施例6と同様にして、複合部材gおよび燃料電池gを作製し、評価した。結果を表6に示す。
なお、複合部材gにクラック等の破損はなかった。
Claims (16)
- イオン伝導性を有する金属酸化物M1を含む固体電解質層と、
イオン伝導性を有する金属酸化物M2および酸化ニッケルを含む第1アノード層と、
前記固体電解質層と前記第1アノード層との間に介在し、イオン伝導性を有する金属酸化物M3および酸化ニッケルを含む第2アノード層と、を備え、
前記第1アノード層における前記酸化ニッケルの体積基準の含有率Cn1と、前記第2アノード層における前記酸化ニッケルの体積基準の含有率Cn2とが、Cn1<Cn2の関係を満たす、燃料電池用電解質層-アノード複合部材。 - 前記Cn1が40~80体積%であり、
前記Cn2が50~90体積%である、請求項1に記載の燃料電池用電解質層-アノード複合部材。 - 前記固体電解質層の厚みTeが3~50μmであり、
前記第1アノード層の厚みT1および前記第2アノード層の厚みT2の合計の厚みと、前記厚みTeとの比率:(T1+T2)/Teが、10以上である、請求項1または2に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M1が、A1B1O3で表わされるペロブスカイト型の結晶構造を有し、 A1サイトが、少なくとも1種の2族元素を含み、
B1サイトが、セリウムおよびジルコニウムの少なくとも1種と、希土類元素と、を含む、請求項1~3のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M1が、
式(1-1):BaCe1-a1Ya1O3-δ
(ただし、0<a1≦0.5、δは酸素欠損量である)、
式(2-1):BaZr1-b1Yb1O3-δ
(ただし、0<b1≦0.5、δは酸素欠損量である)、および、
式(3-1):BaZr1-c1-d1Cec1Yd1O3-δ
(ただし、0<c1<1、0<d1≦0.5、δは酸素欠損量である)
で表される化合物よりなる群から選択される少なくとも1種である、請求項4に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M2が、A2B2O3で表わされるペロブスカイト型の結晶構造を有し、 A2サイトが、少なくとも1種の2族元素を含み、
B2サイトが、セリウムおよびジルコニウムの少なくとも1種と、希土類元素と、を含む、請求項1~5のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M2が、
式(1-2):BaCe1-a2Ya2O3-δ
(ただし、0<a2≦0.5、δは酸素欠損量である)、
式(2-2):BaZr1-b2Yb2O3-δ
(ただし、0<b2≦0.5、δは酸素欠損量である)、および、
式(3-2):BaZr1-c2-d2Cec2Yd2O3-δ
(ただし、0<c2<1、0<d2≦0.5、δは酸素欠損量である)
で表わされる化合物よりなる群から選択される少なくとも1種である、請求項6に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M3が、A3B3O3で表わされるペロブスカイト型の結晶構造を有し、 A3サイトが、少なくとも1種の2族元素を含み、
B3サイトが、セリウムおよびジルコニウムの少なくとも1種と、希土類元素と、を含む、請求項1~7のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M3が、
式(1-3):BaCe1-a3Ya3O3-δ
(ただし、0<a3≦0.5、δは酸素欠損量である)、
式(2-3):BaZr1-b3Yb3O3-δ
(ただし、0<b3≦0.5、δは酸素欠損量である)、および、
式(3-3):BaZr1-c3-d3Cec3Yd3O3-δ
(ただし、0<c3<1、0<d3≦0.5、δは酸素欠損量である)
で表わされる化合物よりなる群から選択される少なくとも1種である、請求項8に記載の燃料電池用電解質層-アノード複合部材。 - 前記金属酸化物M1が、カルシウム、スカンジウムおよびイットリウムよりなる群から選択される少なくとも1種がドープされた二酸化ジルコニウムを含む、請求項1~3のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。
- 前記金属酸化物M2が、カルシウム、スカンジウムおよびイットリウムよりなる群から選択される少なくとも1種がドープされた二酸化ジルコニウムを含む、請求項1~3および10のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。
- 前記金属酸化物M3が、カルシウム、スカンジウムおよびイットリウムよりなる群から選択される少なくとも1種がドープされた二酸化ジルコニウムを含む、請求項1~3、10および11のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。
- 前記第1アノード層および前記第2アノード層の少なくとも一方に含まれる前記酸化ニッケルの少なくとも一部が、金属ニッケルに還元されている、請求項1~12のいずれか一項に記載の燃料電池用電解質層-アノード複合部材。
- イオン伝導性を有する金属酸化物M1を含む固体電解質層用材料と、
イオン伝導性を有する金属酸化物M2およびニッケル化合物N1を含むアノード用材料Aと、
イオン伝導性を有する金属酸化物M3およびニッケル化合物N2を含むアノード用材料Bと、を準備する第1工程と、
前記アノード用材料Aを含む第1アノード層の前駆体層、前記アノード用材料Bを含む第2アノード層の前駆体層および前記固体電解質層用材料を含む固体電解質層の前駆体層が、この順で積層された積層体を形成する第2工程と、
前記積層体を焼成して、前記第1アノード層、前記第2アノード層および前記固体電解質層を形成する第3工程と、を備え、
前記第1アノード層における前記酸化ニッケルの体積基準の含有率Cn1と、前記第2アノード層における前記酸化ニッケルの体積基準の含有率Cn2とが、Cn1<Cn2の関係を満たす、燃料電池用電解質層-アノード複合部材の製造方法。 - さらに、前記第1アノード層および前記第2アノード層に含まれる前記酸化ニッケルの少なくとも一部を還元する第4工程を含む、請求項14に記載の燃料電池用電解質層-アノード複合部材の製造方法。
- 請求項1~請求項13のいずれか一項に記載の電解質層-アノード複合部材と、
カソードと、
前記カソードに酸化剤を供給するための酸化剤流路と、
前記アノードに燃料を供給するための燃料流路と、を備える、燃料電池。
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JP2018139183A (ja) * | 2017-02-24 | 2018-09-06 | 住友電気工業株式会社 | 固体電解質部材、固体酸化物型燃料電池、水電解装置、水素ポンプ及び固体電解質部材の製造方法 |
JP2018139182A (ja) * | 2017-02-24 | 2018-09-06 | 住友電気工業株式会社 | 固体電解質部材、固体酸化物型燃料電池、水電解装置、水素ポンプ及び固体電解質部材の製造方法 |
WO2018230248A1 (ja) * | 2017-06-15 | 2018-12-20 | 住友電気工業株式会社 | 固体電解質部材、固体酸化物型燃料電池、水電解装置、水素ポンプ及び固体電解質部材の製造方法 |
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WO2020166202A1 (ja) | 2019-02-13 | 2020-08-20 | パナソニックIpマネジメント株式会社 | 膜電極接合体および燃料電池 |
US20210013534A1 (en) * | 2018-03-06 | 2021-01-14 | Sumitomo Electric Industries, Ltd. | Electrolyte layer-anode composite member and cell structure |
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JP2017033799A (ja) * | 2015-08-03 | 2017-02-09 | 株式会社日本触媒 | メタルサポートセル |
JP2018139183A (ja) * | 2017-02-24 | 2018-09-06 | 住友電気工業株式会社 | 固体電解質部材、固体酸化物型燃料電池、水電解装置、水素ポンプ及び固体電解質部材の製造方法 |
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US20210013534A1 (en) * | 2018-03-06 | 2021-01-14 | Sumitomo Electric Industries, Ltd. | Electrolyte layer-anode composite member and cell structure |
EP3641039A1 (en) | 2018-10-18 | 2020-04-22 | Panasonic Intellectual Property Management Co., Ltd. | Membrane electrode assembly and fuel cell |
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