JP2013197036A - Fuel cell and method for manufacturing laminated sintered body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell capable of improving power generation characteristics and long-term reliability even if the fuel cell includes an intermediate layer.SOLUTION: A fuel cell 1 comprises: an electrolyte layer 2 formed of a solid electrolyte; a cathode layer 6 provided on one surface of the electrolyte layer 2 via an intermediate layer 3; and an anode layer 7 provided on the other surface of the electrolyte layer 2. The intermediate layer 3 includes a compact intermediate layer 4 arranged on the electrolyte layer 2 side and formed to be compact, and a porous intermediate layer 5 arranged on the cathode layer 6 side of the compact intermediate layer 4 and formed to be more porous than the compact intermediate layer 4. The compact intermediate layer 4 and the porous intermediate layer 5 are formed of the same material. A relative density of the compact intermediate layer 4 is preferably not less than 80%, and a relative density of the porous intermediate layer 5 is preferably in a range from 40% to 75%. The intermediate layer 3 can be formed of a cerium oxide-based oxide. The electrolyte layer 2 can be formed of a zirconium oxide-based oxide or a lanthanum gallate-based oxide.

Description

  The present invention relates to a fuel cell and a method for producing a laminated sintered body, and more particularly to a solid electrolyte fuel cell that uses a solid electrolyte as an electrolyte, and a method for producing a laminated sintered body used for producing the fuel cell. .

  Conventionally, a fuel cell using a solid electrolyte such as stabilized zirconia as an electrolyte is known. The fuel cell has, as its basic structure, an electrolyte layer formed of a solid electrolyte, a cathode layer provided on one surface of the electrolyte layer, and an anode layer provided on the other surface of the electrolyte layer. . A fuel cell in which an intermediate layer is sandwiched between an electrolyte layer and a cathode layer is also known.

  Prior art document 1, which is different from the fuel cell having the intermediate layer, has a fuel cell having an electrolyte layer made of an oxide ion conductor containing cerium oxide, and an anode layer and a cathode layer sandwiching the electrolyte layer. Is disclosed. The electrolyte layer has a dense electrolyte layer disposed on the anode layer side and a porous electrolyte layer disposed on the cathode layer side.

JP 2009-259746 A

However, the prior art has the following problems.
In the case of a fuel cell having an intermediate layer, the microstructure of the intermediate layer greatly affects the power generation characteristics and long-term reliability. That is, it is desirable that the intermediate layer be porous from the viewpoint of securing the bonding property with the cathode layer and the reaction point. On the other hand, when the intermediate layer becomes excessively porous, the bondability with the electrolyte is lowered. Since the decrease in the bonding property increases the ohmic resistance, the power generation characteristics of the fuel cell are deteriorated. Further, when the intermediate layer becomes porous, the cathode component diffuses to the electrolyte layer through the voids to form an insulating reaction product. Therefore, the long-term reliability of the fuel cell is reduced. Therefore, it is difficult for a fuel cell having an intermediate layer to achieve both reduction of ohmic resistance by bonding and suppression of reaction products, and it is difficult to improve power generation characteristics and long-term reliability. is there.

  In addition, the fuel cell of patent document 1 is anxious about the joining property of a dense electrolyte layer and a porous electrolyte layer being bad, ohmic resistance increasing, and power generation performance falling. Further, in this fuel cell, the cathode component diffuses to the dense electrolyte layer through the voids of the porous electrolyte layer during long-term use, and an insulating reaction product is easily formed. For this reason, there is a concern about deterioration of long-term reliability. Therefore, it is difficult to apply this technique to a fuel cell having an intermediate layer.

  The present invention has been made in view of such a background, and intends to provide a fuel cell capable of improving power generation characteristics and improving long-term reliability even when an intermediate layer is provided. . Another object of the present invention is to provide a method for producing a laminated sintered body suitable for use in the production of the fuel cell.

One embodiment of the present invention includes an electrolyte layer formed of a solid electrolyte, a cathode layer provided on one surface of the electrolyte layer via an intermediate layer, and an anode layer provided on the other surface of the electrolyte layer. A fuel cell comprising:
The intermediate layer is disposed on the electrolyte layer side and is densely formed, and the intermediate layer is disposed on the cathode layer side of the dense intermediate layer and is more porous than the dense intermediate layer. A porous intermediate layer formed on
In the fuel cell, the dense intermediate layer and the porous intermediate layer are formed of the same kind of material (claim 1).

Another aspect of the present invention is a method for producing a laminated sintered body that is used in the production of the fuel cell and includes a laminated structure in which the electrolyte layer, the dense intermediate layer, and the porous intermediate layer are laminated in this order. Because
On one side of the unfired electrolyte layer forming sheet formed into a sheet shape containing the raw material powder of the electrolyte layer and the organic material, into a sheet shape containing the raw material powder of the dense intermediate layer and the organic material Simultaneously including the electrolyte layer and the dense intermediate layer bonded to one surface of the electrolyte layer by laminating the formed unfired dense intermediate layer forming sheets, press-bonding, and co-firing. Obtaining a fired body;
After applying the porous intermediate layer forming paste containing the raw material powder of the porous intermediate layer and the organic material on the surface of the dense intermediate layer of the co-fired body, the temperature is equal to or lower than the firing temperature at the time of the co-firing. And a step of firing at a temperature. A method for producing a laminated sintered body according to claim 6.

Still another embodiment of the present invention is used for manufacturing the fuel cell, and manufacturing a laminated sintered body including a laminated structure in which the electrolyte layer, the dense intermediate layer, and the porous intermediate layer are laminated in this order. A method,
A dense intermediate layer forming paste containing the raw material powder of the dense intermediate layer and an organic material on the surface of the electrolyte layer, and a porous intermediate layer forming paste containing the raw material powder of the porous intermediate layer and an organic material In this method of manufacturing a laminated sintered body, the method includes a step of firing after coating in this order (claim 7).

  In a fuel cell using a solid electrolyte as an electrolyte, the electrolyte layer formed from the solid electrolyte is usually dense. In the fuel cell, a dense intermediate layer formed densely is disposed on the electrolyte layer side of the intermediate layer. Therefore, in the fuel cell, when the dense surfaces of the electrolyte layer and the dense intermediate layer are in contact with each other, the junction point is increased and the bondability is improved. On the other hand, in a fuel cell that uses a solid electrolyte as an electrolyte, the cathode layer is usually porous. In the fuel cell, a porous intermediate layer is disposed on the cathode layer side of the dense intermediate layer. Therefore, in the fuel cell, when the rough surfaces of the cathode layer and the porous intermediate layer are engaged with each other, the junction point is increased and the bondability is improved. Further, the dense intermediate layer and the porous intermediate layer are made of the same material. Therefore, the bondability between the dense intermediate layer and the porous intermediate layer is improved. Therefore, the fuel cell can ensure good bondability as a whole. Therefore, even if the fuel cell has an intermediate layer between the electrolyte layer and the cathode layer, ohmic resistance due to the junction can be reduced. Further, the bonding reliability can be improved by improving the bonding property.

  Further, in the fuel cell, a dense intermediate layer is formed on the electrolyte layer side of the intermediate layer. Therefore, even when the fuel cell is used for a long period of time, diffusion of the cathode component into the electrolyte layer is suppressed, and formation of an insulating reaction product that becomes a resistance component can be suppressed.

  As mentioned above, according to the said fuel cell, it becomes possible to make the reduction of the ohmic resistance by joining, and suppression of a reaction product compatible. Therefore, even when the intermediate layer is provided, it is possible to improve power generation characteristics and long-term reliability.

  In the method for producing a laminated sintered body (another aspect) (hereinafter, also referred to as “first production method”), the electrolyte layer forming sheet and the dense intermediate layer forming sheet are superposed and pressure bonded. And co-firing. Therefore, the obtained co-fired body can improve the bondability between the electrolyte layer and the dense intermediate layer, which are made of different materials. Moreover, since the raw material powder of each layer is made into a sheet, the sinterability is improved. Therefore, in the obtained co-fired body, the electrolyte layer and the dense intermediate layer tend to be dense. And after applying the porous intermediate layer forming paste for forming the porous intermediate layer formed of the same kind of material as the dense intermediate layer on the surface of the dense intermediate layer of the co-fired body, Firing is performed at a temperature lower than the firing temperature at the time of simultaneous firing. Therefore, the dense intermediate layer and the porous intermediate layer can be satisfactorily bonded. In addition, this production method also has an advantage that the amount of voids contained in the formed dense intermediate layer and porous intermediate layer can be easily controlled.

  On the other hand, in the above-described method for manufacturing a laminated sintered body (further other embodiment) (hereinafter, sometimes referred to as “second manufacturing method”), one surface of an electrolyte layer that is a sintered body is made of the same kind of material. The dense intermediate layer to be formed, the dense intermediate layer forming paste for forming the porous intermediate layer, and the porous intermediate layer forming paste are applied in this order, and then fired. Therefore, the dense intermediate layer and the porous intermediate layer can be satisfactorily bonded. In addition, this production method has an advantage that the shrinkage rate of the dense intermediate layer and the porous intermediate layer to be formed can be easily controlled.

  Therefore, a laminated sintered body that can be suitably used for producing the fuel cell can be obtained by any method of producing the laminated sintered body.

1 is an explanatory view schematically showing a fuel cell according to Example 1. FIG. It is explanatory drawing which showed the flow of the manufacturing method of the laminated sintered compact concerning Example 1. FIG. It is explanatory drawing which showed the flow of the manufacturing method of the laminated sintered compact concerning Example 2. FIG. FIG. 5 is an explanatory diagram comparing the output density of each fuel cell according to the difference in the layer configuration of the intermediate layer in Experimental Example 1; It is explanatory drawing which compared the output density of each fuel cell in Experimental example 2. FIG. FIG. 10 is a diagram showing the relationship between the relative density of the intermediate layer on the electrolyte layer side and the cathode layer side and the ohmic resistance of the fuel cell in Experimental Example 3. It is the figure which showed the relationship between the thickness of the porous intermediate | middle layer in Example 4, and the ohmic resistance of a fuel cell. FIG. 10 is a diagram showing the relationship between the addition amount of a sintering aid containing Co added to the raw material powder of the dense intermediate layer and the relative density of the dense intermediate layer in Experimental Example 5.

  The fuel cell will be described. In addition, the description of the 1st manufacturing method mentioned later and the description of the 2nd manufacturing method can also be referred as needed.

  The fuel cell has a battery structure in which an anode layer, an electrolyte layer, an intermediate layer, and a cathode layer are laminated in this order. The anode layer and the electrolyte layer, the electrolyte layer and the intermediate layer, and the intermediate layer and the cathode layer are bonded to each other.

  The shape of the fuel cell is not particularly limited, and may be a flat shape such as a flat plate shape or a flat shape, or a cylindrical shape. Preferably, it can be made planar from the viewpoint of excellent productivity. In the fuel cell, for example, the anode layer can function as a support. In addition, the electrolyte layer or the cathode layer can function as a support, and a layer other than the main power generation element can be included as a support separately.

  In the fuel cell, the electrolyte layer is formed of a solid electrolyte. Examples of the solid electrolyte include solid oxide ceramics exhibiting oxygen ion conductivity such as zirconium oxide-based oxide, lanthanum gallate-based oxide, and cerium oxide-based oxide. A fuel cell using solid oxide ceramics as a solid electrolyte is called a solid oxide fuel cell (SOFC).

  As the solid electrolyte, a zirconium oxide-based oxide or a lanthanum gallate-based oxide can be suitably used. When the solid electrolyte is a zirconium oxide-based oxide, there are advantages such as excellent strength and thermal stability. Further, when the solid electrolyte is a lanthanum gallate oxide, there are advantages such as a low-temperature operation of the battery and a reduction in the electric resistance of the battery. These can be used alone or in combination of two or more.

Examples of the zirconium oxide-based oxide include one or two rare earth oxides such as Y ₂ O ₃ , Sc ₂ O ₃ , Gd ₂ O ₃ , Sm ₂ O ₃ , Yb ₂ O ₃ , and Nd ₂ O _3. Stabilized zirconia containing more than one species can be exemplified. Examples of the lanthanum gallate oxide include LaGaO ₃ and LaGaO ₃ in which part of La is replaced with Sr and the like, part of Ga is replaced with Mg and the like, and Co and Fe are added to the Ga site. The thing etc. can be illustrated. To be more _{specific, La 0.8 Sr 0.2 Ga 0.2 Mg} 0.8 O 3 or the like of _{La 1-s Sr s Ga 1} -m Mg m O x, La 0.8 Sr 0.2 ( _{Ga 0.2 Mg 0.8) 1-x} Co x O 3 or the like of _{La 1-s Sr s (Ga} 1-m Mg m) 1-x Co x O y, La 0.8 Sr 0.2 (Ga _{0.2 Mg 0.8) 1-x Fe} x O 3 La 1-s Sr s (Ga 1-m Mg m such) _{1-x Fe} x _{O y} or the like can be exemplified.

  The thickness of the electrolyte layer can be, for example, about 100 to 300 μm when the electrolyte layer is a support, and can be about 3 to 30 μm when the electrolyte layer is not a support.

  In the fuel cell, the intermediate layer has a dense intermediate layer and a porous intermediate layer, and both layers are bonded to each other. The dense intermediate layer is formed dense, and the porous intermediate layer is formed porous with more voids than the dense intermediate layer. That is, it can be said that the two layers have different relative densities. Specifically, the relative density of the dense intermediate layer is larger than the relative density of the porous intermediate layer (the relative density of the porous intermediate layer is smaller than the relative density of the dense intermediate layer).

The relative density can be measured as follows. That is, using a scanning electron microscope (SEM), a cross-sectional image obtained by cutting in a direction perpendicular to the layer surface is photographed at five or more locations in the direction along the layer surface (magnification 10,000 times). At this stage, the dense intermediate layer is formed more densely than the porous intermediate layer due to the obvious difference in void volume (the porous intermediate layer is formed more porous than the dense intermediate layer). In some cases. Next, the obtained cross-sectional image is image-analyzed with image analysis software (“WinROOF” manufactured by Mitani Corporation), and the area of the skeleton and voids forming the layer is calculated from the difference in contrast. Calculate the skeletal ratio of one side.
Skeletal ratio (%) = (Area of skeleton / (Area of skeleton + Area of void)) × 100
Similarly, the skeleton ratio of each photographing location is calculated, and the average value thereof is set as the relative density.

  Specifically, the relative density of the dense intermediate layer may be 80% or more, and the relative density of the porous intermediate layer may specifically be in the range of 40 to 75% (Claim 2). In this case, the ohmic resistance can be further reduced. As a result, a fuel cell with even better power generation performance can be obtained.

  The relative density of the dense intermediate layer is preferably 83% or more, more preferably 85% or more, from the viewpoint of obtaining a sufficient effect of reducing ohmic resistance and suppressing the diffusion of the cathode component. In addition, the relative density of the dense intermediate layer is preferably 98% or less, more preferably 95% or less, from the viewpoint of reducing ohmic resistance, manufacturability, and the like. On the other hand, the relative density of the porous intermediate layer is preferably 43% or more, more preferably 45% or more, from the viewpoint of reducing ohmic resistance. Further, the relative density of the porous intermediate layer is preferably 73% or less, more preferably 70% or less, from the viewpoints of reducing ohmic resistance and improving the bonding property with the cathode layer.

  The dense intermediate layer can be formed of one layer or two or more layers (multiple layers). The porous intermediate layer can also be formed of one layer or two or more layers (multiple layers). When the dense intermediate layer and / or the porous intermediate layer is formed of two or more layers, the relative densities of the layers forming the dense intermediate layer and the porous intermediate layer can be different values. In this case, there is an advantage that the relative density of the dense intermediate layer and the porous intermediate layer can be finely controlled. Therefore, the intermediate layer specifically includes, for example, a configuration in which the dense intermediate layer is one layer and the porous intermediate layer is one layer, or the dense intermediate layer is one layer, and the porous intermediate layer has a relative density. It can be set as the structure which consists of two or more different layers. In the latter case, the layers forming the porous intermediate layer can be arranged with an inclination in relative density so that the relative density on the cathode layer side becomes smaller. This is because there are advantages such as improved bondability with the cathode layer and increased reaction points.

  The dense intermediate layer and the porous intermediate layer are formed of the same material. Here, the same kind of material means not only a material that is exactly the same, but also a material that includes substantially the same main component that occupies 50 mol% or more. Therefore, for example, even if the kind of dopant and the amount of doping are different, a material that can be said to be substantially the same as the substance to be doped as the main component is included in the same kind of material.

  In the fuel cell, specifically, the intermediate layer can be formed of a cerium oxide-based oxide. That is, both the dense intermediate layer and the porous intermediate layer can be formed from a cerium oxide-based oxide. In this case, there are advantages such as excellent oxygen ion conductivity and low temperature operation of the battery. In addition, the dense intermediate layer and the porous intermediate layer may be specifically formed from the same cerium oxide-based oxide, or from cerium oxide-based oxides having different dopant types and / or different doping amounts. It may be formed.

  Examples of the cerium oxide-based oxide include ceria and ceria doped with one or more elements selected from Gd, Sm, Y, La, Nd, Yb, Ca, Dr, and Ho. Examples thereof include system solid solutions. The doping amount of the above element can be about 5 to 55 mol%, preferably about 10 to 50 mol%.

  The dense intermediate layer and the porous intermediate layer can contain additives such as a sintering aid. For example, the dense intermediate layer can contain a sintering aid containing one or more elements selected from Ca, Mg, Co, Cu, Fe, Ni, and Zn. This is because the relative density of the dense intermediate layer can be easily increased. In this case, the content of the additive contained in the dense intermediate layer can be preferably about 0.1 to 1 mol%, more preferably about 0.2 to 0.7 mol%.

  In the fuel cell, the total thickness of the intermediate layer may be 15 μm or less, and the thickness of the porous intermediate layer may be 2/3 or less of the total thickness of the intermediate layer. In this case, the ohmic resistance can be further reduced. As a result, a fuel cell with even better power generation performance can be obtained.

  The total thickness of the intermediate layer is preferably 15 μm or less, more preferably 10 μm or less, from the viewpoint of the electric resistance of the battery. The total thickness of the intermediate layer is preferably 3 μm or more, more preferably 5 μm or more, from the viewpoints of securing the intermediate layer, forming a dense intermediate layer, and a porous intermediate layer. The thickness of the porous intermediate layer is preferably 2/3 or less of the total thickness of the intermediate layer, more preferably 3/5 of the total thickness of the intermediate layer, from the viewpoint of stability of the effect of reducing the ohmic resistance. It can be as follows. The thickness of the porous intermediate layer is preferably 1/3 or more of the total thickness of the intermediate layer, more preferably the intermediate layer, from the viewpoint of securing the porous intermediate layer, the formability of the porous intermediate layer, and the like. It can be set to 1/2 or more of the total thickness.

  In the fuel cell, examples of the cathode layer include perovskite oxides having conductivity such as lanthanum-manganese oxide, lanthanum-cobalt oxide, and lanthanum-iron oxide. . The thickness of the cathode layer can be, for example, about 30 to 100 μm. The anode layer can be exemplified by, for example, metallic nickel, nickel oxide, and a cermet of these and a solid electrolyte. As the solid electrolyte in this case, zirconium oxide-based oxide, cerium oxide-based oxide, lanthanum gallate-based oxide, or the like can be used. The thickness of the anode layer can be, for example, about 150 to 800 μm when the anode layer is used as a support, and about 30 to 100 μm when the anode layer is not used as a support.

  Next, the manufacturing method (other aspect) (1st manufacturing method) of the said laminated sintered body is demonstrated. In addition, the description of the said fuel cell and the description of the 2nd manufacturing method mentioned later can be referred to as needed.

  In the first manufacturing method, an unfired anode layer forming sheet formed into a sheet shape including the anode layer raw material powder and the organic material may be laminated on the other surface of the electrolyte layer forming sheet. it can. The electrolyte layer forming sheet, the dense intermediate layer forming sheet, and the anode layer forming sheet are all unfired, that is, raw sheets. The electrolyte layer forming sheet becomes an electrolyte layer by firing. The dense intermediate layer forming sheet becomes a dense intermediate layer by firing. The anode layer forming sheet becomes an anode layer by firing.

  In addition, as a raw material powder of an electrolyte layer, the powder containing solid electrolytes, such as a zirconium oxide type oxide mentioned above and a lanthanum gallate type oxide, can be used. As the raw material powder for the dense intermediate layer, a powder containing the above-described cerium oxide-based oxide or the like can be used. As the raw material powder for the porous intermediate layer, a powder containing the above-described cerium oxide-based oxide or the like can be used.

  The pressure bonding conditions at the time of the pressure bonding include, for example, a CIP (cold isostatic pressing) molding method, a HIP (hot isostatic pressing) molding method, and the like, and a temperature of about 40 to 120 ° C, preferably 60 to 100 ° C. The pressure can be about 5 to 80 MPa, preferably about 10 to 60 MPa, and the pressing time is about 5 to 45 minutes, preferably about 10 to 30 minutes. The firing conditions for the simultaneous firing may be, for example, a firing temperature of about 1200 to 1500 ° C., preferably about 1250 to 1400 ° C., a firing time of about 60 to 300 minutes, and preferably about 90 to 180 minutes. .

  The paste coating method is not particularly limited, and various coating means such as a screen printing method, a doctor blade method, and a brush coating method can be used.

  The porous intermediate layer forming paste that has been coated becomes a porous intermediate layer by firing. The firing conditions may be, for example, a firing temperature of about 1050 to 1200 ° C., preferably about 1100 to 1200 ° C., a firing time of about 60 to 300 minutes, and preferably about 90 to 180 minutes. The reason why the firing temperature here is set to a temperature equal to or lower than the firing temperature at the time of simultaneous firing is to facilitate ensuring the porosity of the porous intermediate layer.

  The organic material contains a binder component for binding each raw material powder and disappears by firing, and conventionally known materials can be appropriately selected and used.

  Next, a method for manufacturing the laminated sintered body (another aspect) (second manufacturing method) will be described. In addition, the description of the said fuel cell and the said 1st manufacturing method can be referred as needed.

  In the second production method, the electrolyte layer can be prepared, for example, by firing the electrolyte layer forming sheet. An anode layer may be bonded to the other surface of the electrolyte layer. In this case, for example, the anode layer forming sheet can be laminated on the other surface of the electrolyte layer forming sheet, pressure-bonded, and then simultaneously fired. In addition, after the anode layer forming sheet is fired to obtain the anode layer, the electrolyte layer forming slurry containing the raw material powder of the electrolyte layer and the organic material is applied and fired on the surface of the anode layer. Can also be prepared. Furthermore, after the electrolyte layer forming sheet is fired to obtain the electrolyte layer, the anode layer forming paste can be applied to the surface of the electrolyte layer and then fired.

  In the second production method, the firing condition is, for example, a firing temperature of about 1200 to 1500 ° C., preferably about 1250 to 1400 ° C., a firing time of about 60 to 300 minutes, preferably about 90 to 180 minutes. be able to.

  In the first and second manufacturing methods described above, the average particle diameter d1 of the raw material powder of the dense intermediate layer and the average particle diameter d2 of the raw material powder of the porous intermediate layer satisfy the relationship of d1 <d2. Good (claim 8).

  In this case, the sinterability of the dense intermediate layer at the time of firing is improved as compared with the porous intermediate layer. Therefore, the dense intermediate layer is easily formed densely, and the porous intermediate layer is easily formed porous. Therefore, it becomes easy to obtain an intermediate layer having the above structure. Therefore, it is advantageous for improving the power generation characteristics.

  In particular, when the intermediate layer is formed of a cerium oxide-based oxide, the cerium oxide-based oxide has poor sinterability. Therefore, if the above relationship is satisfied, the dense intermediate layer is formed densely. It is easy and advantageous. Further, when the second manufacturing method satisfies the above relationship, the above effect is enhanced. This is because the second production method produces the dense intermediate layer from the paste, and therefore has lower sinterability than the first production method produces the dense intermediate layer from the sheet.

  Specifically, the average particle diameter d1 is preferably 0.5 μm or less, more preferably 0.3 μm from the viewpoint of improving the sinterability at a necessary temperature and making the dense intermediate layer easily dense. It can be as follows. The average particle diameter d1 is preferably 0.05 μm or more, more preferably 0.1 μm or more, from the viewpoint of controllability of the crystal particle diameter. On the other hand, specifically, the average particle diameter d2 is preferably 0.8 μm or more from the viewpoint of easily making the porous intermediate layer porous at a necessary temperature. The average particle diameter d2 is preferably 1.5 μm or less, more preferably 1.2 μm or less, from the viewpoint of improving the bondability with the cathode layer.

The average particle size is determined by JIS JIS using a particle size distribution measuring device by laser diffraction / scattering method.
It is a value of 50% diameter in a volume-based integrated fraction measured in accordance with R1629.

  In the first and second manufacturing methods described above, a powder containing one or more elements selected from Ca, Mg, Co, Cu, Fe, Ni, and Zn in the raw material powder of the dense intermediate layer. A binder can be added in the range of 0.1 to 1 mol% (claim 9).

  In this case, the sinterability of the dense intermediate layer can be improved without affecting the oxygen ion conductivity of the formed dense intermediate layer. Therefore, the dense intermediate layer is easily formed densely, and the porous intermediate layer is easily formed porous. Therefore, it becomes easy to obtain an intermediate layer having the above structure. In addition, the bondability between the dense intermediate layer and the porous intermediate layer is improved. This is presumably because the effect of improving the sinterability also appears at the interface between the dense intermediate layer and the porous intermediate layer. Therefore, the above case is advantageous in improving the power generation characteristics of the fuel cell.

  Further, the addition of the sintering aid has a great effect when applied to the second production method. Since the dense intermediate layer is formed by applying and baking the paste, the sinterability is usually worse than when the dense intermediate layer is formed by baking the sheet. However, the addition of the sintering aid improves the sinterability, and the dense intermediate layer tends to become dense even by applying and baking the paste.

  The method for manufacturing the fuel cell is not particularly limited as long as the structure described above can be used. The fuel cell can be preferably manufactured using, for example, a laminated sintered body obtained by the first manufacturing method or the second manufacturing method. Specifically, the anode layer may be bonded to the side opposite to the intermediate layer side of the electrolyte layer in the laminated sintered body, and the cathode layer may be bonded to the surface of the porous intermediate layer. When the laminated sintered body has an anode layer, the anode layer may be omitted and the cathode layer may be bonded. Thereby, a fuel cell single cell is obtained. Further, when a plurality of single cells are stacked via separators, a fuel cell stack can be configured.

  Hereinafter, the fuel cell of an Example and the manufacturing method of a laminated sintered compact are demonstrated using drawing. In addition, about the same member, it demonstrates using the same code | symbol.

Example 1
As shown in FIG. 1, a fuel cell 1 of Example 1 includes an electrolyte layer 2 formed of a solid electrolyte, a cathode layer 6 provided on one surface of the electrolyte layer 2 via an intermediate layer 3, and an electrolyte layer. 2 and an anode layer 7 provided on the other surface. The intermediate layer 3 has a dense intermediate layer 4 and a porous intermediate layer 5. The dense intermediate layer 4 is disposed on the electrolyte layer 2 side and is densely formed. The porous intermediate layer 5 is disposed on the cathode layer 6 side of the dense intermediate layer 4 and is more porous than the dense intermediate layer 4. The dense intermediate layer 4 and the porous intermediate layer 5 are formed of the same material.

In this example, specifically, the electrolyte layer 2 is formed of yttria-stabilized zirconia (hereinafter, 8YSZ) containing 8 mol% of Y ₂ O ₃ , which is a zirconium oxide-based oxide, and has a thickness of 10 μm. It is. The intermediate layer 3 is made of ceria (hereinafter, 10GDC) doped with 10 mol% of Gd, which is a cerium oxide-based oxide. More specifically, the dense intermediate layer 4 and the porous intermediate layer 5 are made of 10 GDC having different relative densities. The relative density of the dense intermediate layer 4 by the measurement method described above is 85%, and the relative density of the porous intermediate layer 5 is 58%. In calculating the relative density, image analysis software (manufactured by Mitani Corporation, “WinROOF Ver. 5.0”) was used. Further, the total thickness of the intermediate layer 3 is 10 μm, the thickness of the dense intermediate layer 4 is 4 μm, and the thickness of the porous intermediate layer 5 is 6 μm. The cathode layer 6 is made of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 (hereinafter referred to as LSCF) and has a thickness of 50 μm. The anode layer 7 is made of Ni-8YSZ cermet and has a thickness of 800 μm. The fuel cell 1 of this example has a flat plate cell structure in which each of the layers 2, 3, 6, and 7 is formed in a flat shape, and the anode layer 7 is used as a support.

  Moreover, the manufacturing method of the laminated sintered body 12 according to Example 1 is a manufacturing method of the laminated sintered body used for manufacturing the fuel cell 1 according to Example 1. The obtained laminated sintered body 12 includes a laminated structure in which the electrolyte layer 2, the dense intermediate layer 4, and the porous intermediate layer 5 are laminated in this order.

  As shown in FIG. 2, the method for manufacturing the laminated sintered body 12 of this example is a non-fired electrolyte layer forming sheet 20 formed into a sheet shape including the raw material powder 201 of the electrolyte layer 2 and the organic material 202. An unfired dense intermediate layer forming sheet 40 formed into a sheet shape including the raw material powder 401 of the dense intermediate layer 4 and the organic material 402 is laminated on one surface of the dense intermediate layer 4, pressed, and then simultaneously fired. Thus, the step of obtaining the co-fired body 11 including the electrolyte layer 2 and the dense intermediate layer 4 bonded to one surface of the electrolyte layer 2, and the surface of the dense intermediate layer 4 of the co-fired body 11 are porous. After the porous intermediate layer forming paste 51 including the raw material powder 501 of the intermediate layer 5 and the organic material 512 is applied, the method includes a step of baking at a temperature equal to or lower than the baking temperature at the time of simultaneous baking.

  In this example, specifically, the case where the laminated sintered body 12 further includes an anode layer 7 on the side of the electrolyte layer 2 opposite to the dense intermediate layer 4 will be described. However, the laminated structure of the laminated sintered body 12 is not limited to this, and may be a laminated structure in which the electrolyte layer 2, the dense intermediate layer 4, and the porous intermediate layer 5 are laminated in this order. Good. In this example, when the electrolyte layer forming sheet 20 and the dense intermediate layer forming sheet 40 are laminated, the unfired anode formed into a sheet shape further including the raw material powder 701 of the anode layer 7 and the organic material 702 The layer forming sheet 70 is laminated on the other surface of the electrolyte layer forming sheet 20, and the above-described pressure bonding is performed. More specific description will be given below.

(Preparation of each material)
8YSZ powder (average particle size: 0.6 μm), polyvinyl butyral (organic material), isoamyl acetate, 2-butanol and ethanol (mixed solvent) are mixed in a ball mill to prepare a slurry for forming an electrolyte layer. did. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare an electrolyte layer forming sheet 20. The thickness of the electrolyte layer forming sheet 20 was adjusted so as to be the thickness of the electrolyte layer 2 when the laminated sintered body 12 was formed.

  NiO powder (average particle size: 0.6 μm), 8YSZ powder (average particle size: 0.6 μm), carbon, polyvinyl butyral (organic material), isoamyl acetate, 2-butanol and ethanol (mixed solvent) Were mixed by a ball mill to prepare an anode layer forming slurry. The mass ratio of NiO powder and 8YSZ powder was 60:40. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare an anode layer forming sheet 70. The thickness of the anode layer forming sheet 70 was adjusted to be the thickness of the anode layer 7 when the laminated sintered body 12 was formed.

  10 GDC powder (average particle diameter d1: 0.3 μm), polyvinyl butyral (organic material), isoamyl acetate, 2-butanol and ethanol (mixed solvent) are mixed in a ball mill to form a dense intermediate layer A slurry (1) was prepared. This slurry (1) was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a dense intermediate layer forming sheet 40. The thickness of the dense intermediate layer forming sheet 40 was adjusted to be the thickness of the dense intermediate layer 4 when the laminated sintered body 12 was formed.

  A porous intermediate layer forming paste 51 was prepared by mixing 10 GDC powder (average particle diameter d2: 0.8 μm), ethyl cellulose (organic material), and terpineol (solvent) with a ball mill.

(Formation of co-fired body)
The anode layer forming sheet 70, the electrolyte layer forming sheet 20, and the dense intermediate layer forming sheet 40 were laminated in this order, and each sheet was pressure-bonded using the CIP molding method. The CIP molding conditions were a temperature of 80 ° C., a pressing force of 50 MPa, and a pressing time of 10 minutes. Thereafter, this pressure-bonded body was fired at 1350 ° C. for 2 hours. As a result, the co-fired body 11 (anode layer 7 / node) comprising the electrolyte layer 2, the dense intermediate layer 4 joined to one surface of the electrolyte layer 2, and the anode layer 7 joined to the other surface of the electrolyte layer 2 is obtained. Electrolyte layer 2 / dense intermediate layer 4) was obtained.

(Formation of laminated sintered body)
The porous intermediate layer forming paste 51 was screen-printed on the surface of the dense intermediate layer 4 of the obtained co-fired body 11 and fired at 1200 ° C. for 2 hours. The thickness of the paste during screen printing was adjusted so as to be the thickness of the porous intermediate layer 5 when the laminated sintered body 12 was formed. Thus, a laminated sintered body 12 having a laminated structure in which the anode layer 7, the electrolyte layer 2, the dense intermediate layer 4, and the porous intermediate layer 5 are laminated in this order was obtained.

  The fuel cell 1 of Example 1 described above is manufactured using the laminated sintered body 12 obtained in this way. Specifically, a cathode layer forming paste was prepared by mixing LSCF powder (average particle size: 0.5 μm), ethyl cellulose (organic material), and terpineol (solvent) with a ball mill. Then, the cathode layer forming paste was screen-printed on the surface of the porous intermediate layer 5 of the obtained laminated sintered body 12 and fired at 1000 ° C. for 2 hours. In addition, the thickness of the paste at the time of screen printing was adjusted so that it might become the thickness of the said cathode layer 6 after baking. As a result, the cathode layer 6 was joined to the surface of the porous intermediate layer 5 of the laminated sintered body 12 to obtain the fuel cell 1 of Example 1.

(Example 2)
The fuel cell 1 of Example 2 basically has the same cell structure as the fuel cell 1 of Example 1. However, the fuel cell 1 of Example 2 was obtained using the laminated sintered body 12 produced by using the method for producing the laminated sintered body 12 according to Example 2 described later. Therefore, the relative density of the intermediate layer 3 is different from that of the fuel cell 1 of the first embodiment. Specifically, in the fuel cell 1 of Example 2, the relative density of the dense intermediate layer 4 is 94%, and the relative density of the porous intermediate layer 5 is 56%. Hereinafter, the manufacturing method of the laminated sintered body 12 according to Example 2 will be described.

  The method for producing the laminated sintered body 12 according to Example 2 is a method for producing the laminated sintered body 12 used for producing the fuel cell 1 according to Example 2. The obtained laminated sintered body 12 includes a laminated structure in which the electrolyte layer 2, the dense intermediate layer 4, and the porous intermediate layer 5 are laminated in this order.

  As shown in FIG. 3, the method for manufacturing the laminated sintered body 12 of this example is for forming a dense intermediate layer including raw material powder 401 of the dense intermediate layer 4 and an organic material 412 on one surface of the electrolyte layer 2. After the paste 41, the porous intermediate layer forming paste 51 including the raw material powder 501 of the porous intermediate layer 5 and the organic material 512 are applied in this order, there is a step of baking.

  In this example, specifically, the case where the laminated sintered body 12 further includes an anode layer 7 on the side of the electrolyte layer 2 opposite to the dense intermediate layer 4 will be described. However, the laminated structure of the laminated sintered body 12 is not limited to this, and may be a laminated structure in which the electrolyte layer 2, the dense intermediate layer 4, and the porous intermediate layer 5 are laminated in this order. Good. In this example, the anode layer forming sheet 70 is laminated on the other surface of the electrolyte layer forming sheet 20, pressure-bonded, and then co-fired, whereby the electrolyte layer 2 (anode layer 7 / An electrolyte layer 2) is used. More specific description will be given below.

(Preparation of each material)
In the same manner as in Example 1, an electrolyte layer forming sheet 20 and an anode layer forming sheet 70 were produced. Thereafter, the anode layer forming sheet 70 and the electrolyte layer forming sheet 20 were laminated in this order, and each sheet was pressure-bonded using the CIP molding method. The CIP molding conditions were a temperature of 80 ° C., a pressing force of 50 MPa, and a pressing time of 10 minutes. Next, this pressure-bonded body was fired at 1350 ° C. for 2 hours. Thus, a sintered body (anode layer 7 / electrolyte layer 2) composed of the electrolyte layer 2 and the anode layer 7 joined to the other surface of the electrolyte layer 2 was prepared.

  A dense intermediate layer forming paste (1) 41 was prepared by mixing 10 GDC powder (average particle size d1: 0.3 μm), ethyl cellulose (organic material), and terpineol (solvent) with a ball mill.

  A porous intermediate layer forming paste 51 was prepared by mixing 10 GDC powder (average particle diameter d2: 0.8 μm), ethyl cellulose (organic material), and terpineol (solvent) with a ball mill.

(Formation of laminated sintered body)
The dense intermediate layer forming paste (1) 41 and the porous intermediate layer forming paste 51 are screen-printed in this order on one surface of the electrolyte layer 2 in the prepared sintered body and fired at 1200 ° C. for 2 hours. did. In addition, the thickness of each paste at the time of screen printing was adjusted so that it might become the thickness of the dense intermediate | middle layer 4 and the porous intermediate | middle layer 5, respectively, when the laminated sintered compact 12 was formed. Thus, a laminated sintered body 12 having a laminated structure in which the anode layer 7, the electrolyte layer 2, the dense intermediate layer 4, and the porous intermediate layer 5 are laminated in this order was obtained.

  The fuel cell 1 of Example 2 described above was manufactured in the same manner as Example 1 using the laminated sintered body 12 thus obtained.

(Experimental example 1)
A cell power generation test was performed using Sample 1 according to the fuel cell of Example 1, Sample 2 according to the fuel cell of Example 2, Sample 3 as the fuel cell of the comparative example, and Sample 4, which will be described.

  According to substantially the same procedure as in Example 1, a co-fired body (anode layer / electrode layer) comprising an electrolyte layer, a dense intermediate layer bonded to one surface of the electrolyte layer, and an anode layer bonded to the other surface of the electrolyte layer. Electrolyte layer / dense intermediate layer) was obtained. However, the thickness of the dense intermediate layer forming sheet was adjusted so that the thickness of the dense intermediate layer was 10 μm. Thereafter, the co-fired body was directly used as a laminated sintered body, and a cathode layer was bonded to the surface of the dense intermediate layer in the same manner as in Example 1. As a result, a fuel cell of Sample 3 was obtained. That is, the fuel cell of Sample 3 is composed only of a dense intermediate layer having one intermediate layer.

  Further, in Example 2, the porous intermediate layer forming paste was screen-printed on the one surface of the electrolyte layer in the prepared sintered body without screen-printing the dense intermediate layer forming paste. Baked. However, the thickness of the paste during screen printing was adjusted so that the thickness of the porous intermediate layer was 10 μm. Thereafter, a cathode layer was bonded to the surface of the porous intermediate layer in the same manner as in Example 2. As a result, a fuel cell of Sample 4 was obtained. That is, the fuel cell of Sample 4 is composed of only one porous intermediate layer.

In the power generation test, the battery operating temperature was 800 ° C. or 700 ° C. Further, 97 vol% H ₂ -3 vol% H ₂ O fuel gas was supplied to the anode layer at a flow rate of 0.1 L / min. Further, air as an oxidant gas was supplied to the cathode layer at a flow rate of 0.1 L / min.

  As shown in FIG. 4, it can be seen that the fuel cells of Sample 3 and Sample 4 have low output density and poor power generation characteristics of the cells. This is because the fuel cell of Sample 3 has poor bondability between the porous cathode layer and the dense intermediate layer, and the ohmic resistance has increased. This is because the fuel cell of Sample 4 has poor adhesion between the dense electrolyte layer and the porous intermediate layer, and has increased ohmic resistance. Therefore, it can be said that the fuel cells of Sample 3 and Sample 4 are inferior in bondability and therefore have low bonding reliability. In the fuel cell of Sample 4, since the porous intermediate layer is joined to the electrolyte layer, the cathode component is likely to diffuse to the electrolyte layer through the porous intermediate layer during long-term use, and the long-term reliability is also low. It can be said.

  On the other hand, it can be seen that the fuel cells of Sample 1 and Sample 2 have high power density and excellent cell power generation characteristics. This is because the fuel cells of Sample 1 and Sample 2 adopt the above-described configuration, so that the same kind of fuel cell is formed between the dense electrolyte layer and the dense intermediate layer, between the porous cathode layer and the porous intermediate layer. This is because the bonding property between the dense intermediate layer and the porous intermediate layer of the material is improved, and the ohmic resistance due to the bonding is reduced. Therefore, it can be said that the fuel cells of Sample 1 and Sample 2 have high bonding reliability and high bonding reliability.

  In particular, the fuel cell of sample 1 was superior in the power generation performance of the cell as compared with the fuel cell of sample 2. This is because the electrolyte layer forming sheet and the dense intermediate layer forming sheet are laminated, pressure-bonded, and co-fired, so that the bondability between the electrolyte layer and the dense intermediate layer, which are different from each other, is easily improved. This is probably because In addition, it is considered that it was easy to improve the bonding property between the two layers because the dense intermediate layer and the porous intermediate layer of the same material were bonded together by baking at a temperature lower than the baking temperature at the time of simultaneous baking. It is done.

  In the fuel cells of Sample 1 and Sample 2, a dense intermediate layer is interposed between the electrolyte layer and the cathode layer. Therefore, diffusion of the cathode component to the electrolyte layer can be suppressed even when used for a long time. Therefore, it can be said that formation of an insulating reaction product is suppressed and long-term reliability can be improved.

  As described above, according to the fuel cell, it is possible to achieve both reduction of ohmic resistance due to bonding and suppression of reaction products, and to improve power generation characteristics and long-term reliability even when an intermediate layer is provided. Can do.

(Experimental example 2)
Sample 1 according to the fuel cell of Example 1, Sample 2 according to the fuel cell of Example 2, Sample 5 which is a modification of the fuel cell of Example 1, and Sample 6 which is a modification of the fuel cell of Example 2 Since the cell power generation test was conducted, this will be described.

  10GDC powder (average particle size d1: 0.3 μm) to which 0.5 mol% of cobalt oxide (sintering aid) is added, polyvinyl butyral (organic material), isoamyl acetate, 2-butanol and ethanol (mixed solvent) Were mixed with a ball mill to prepare a dense intermediate layer forming slurry (2). The average particle diameter d1 of the 10GDC powder of the slurry (2) and the average particle diameter d2 of the 10GDC powder of the porous intermediate layer forming paste satisfy the relationship d1 <d2.

  A fuel cell of Sample 5 was obtained in the same manner as in Example 1, except that the dense intermediate layer forming slurry (2) was used instead of the dense intermediate layer forming slurry (1).

  Further, 10 GDC powder (average particle diameter d1: 0.3 μm) to which 0.5 mol% of cobalt oxide (sintering aid) is added, ethyl cellulose (organic material), and terpineol (solvent) are mixed in a ball mill. Thus, a dense intermediate layer forming paste (2) was prepared. The average particle diameter d1 of the 10GDC powder of the paste (2) and the average particle diameter d2 of the 10GDC powder of the porous intermediate layer forming paste satisfy the relationship of d1 <d2.

  A fuel cell of Sample 6 was obtained in the same manner as in Example 2, except that the dense intermediate layer forming paste (2) was used instead of the dense intermediate layer forming paste (1).

  The conditions for the power generation test are the same as in Experimental Example 1. As a result, as shown in FIG. 5, it can be seen that the fuel cell of sample 5 has improved power generation characteristics compared to the fuel cell of sample 1. Further, it can be seen that the power generation characteristics of the fuel cell of sample 6 are improved as compared with the fuel cell of sample 2. This is because the relationship of d1 <d2 is adopted and a configuration in which a sintering aid is added to the raw material powder of the dense intermediate layer is adopted.

(Experimental example 3)
A plurality of fuel cell samples having an intermediate layer having a two-layer structure were prepared, and the relationship between relative density and ohmic resistance was investigated. Specifically, the prepared fuel cell intermediate layer of each sample has a first layer disposed on the electrolyte layer side and a second layer disposed on the cathode layer side. The total thickness of the intermediate layer was 10 μm, the thickness of the first layer was 4 μm, and the thickness of the second layer was 6 μm.

  Each prepared sample is roughly divided into a first sample group and a second sample group. In the first sample group, the relative density of the second layer on the cathode layer side is about 57%, and the relative density of the first layer on the electrolyte layer side is different. On the other hand, in the second sample group, the relative density of the first layer on the electrolyte layer side is about 86%, and the relative density of the second layer on the cathode layer side is different. In addition, about these samples, about another structure, it is the same structure as Example 1. FIG. The relative density was adjusted by changing the particle size of the raw material powder and the amount of organic material used in both the first sample group and the second sample group.

  And the fuel cell of each said sample group was operated at 800 degreeC, alternating current impedance measurement was performed by the four probe method, and ohmic resistance was measured from the Cole-Cole plot.

  From the results of the first sample group in FIG. 6, among the intermediate layers, the layer disposed on the electrolyte layer side tends to decrease the ohmic resistance as the relative density increases, that is, as it becomes dense. In particular, it can be seen that when the relative density is 80% or more, the effect of reducing the ohmic resistance is large and is stabilized to some extent. On the other hand, the layer disposed on the cathode layer side of the intermediate layer tends to have a large decrease in ohmic resistance when the relative density is 75% or less. It can be seen that the effect of reducing ohmic resistance is large when the relative density is in the range of 40% to 75%. When the relative density is less than 40%, the ohmic resistance tends to increase again.

  From the above results, it can be said that the ohmic resistance can be further reduced when the relative density of the dense intermediate layer is 80% or more and the relative density of the porous intermediate layer is in the range of 40 to 75%. Therefore, when the intermediate layer has such a configuration, it can be said that a fuel cell with further excellent power generation performance can be obtained.

(Experimental example 4)
A plurality of fuel cell samples having an intermediate layer having a two-layer structure were prepared, and the relationship between the thickness of the porous intermediate layer and ohmic resistance was investigated. Specifically, the total thickness of the intermediate layer in the fuel cell of each prepared sample was 15 μm, and the thickness of the porous intermediate layer was as shown in FIG. Therefore, the thickness of the dense intermediate layer in each sample is the difference between the total thickness of the intermediate layer and the thickness of the porous intermediate layer shown in FIG. In these samples, the other configurations are the same as those in Example 2. The thickness of the dense intermediate layer and the thickness of the porous intermediate layer were both adjusted by changing the conditions during screen printing of the paste. Then, the ohmic resistance was measured in the same manner as in Experimental Example 3.

  As shown in FIG. 7, when the total thickness of the intermediate layer is 15 μm or less and the thickness of the porous intermediate layer is 2/3 or less of the total thickness of the intermediate layer, ohmic resistance can be further reduced. I can say that. Therefore, in this case, it can be said that a fuel cell having further excellent power generation performance can be obtained.

(Experimental example 5)
The relationship between the amount of sintering aid added to the raw powder of the dense intermediate layer and the relative density of the dense intermediate layer was investigated.

  Specifically, cobalt oxide, which is a sintering aid containing Co, was used except that each 10 GDC powder (average particle diameter d1: 0.3 μm) added at a ratio (mol%) shown in FIG. 8 was used. In the same manner as in Example 2, a plurality of dense intermediate layer forming pastes were prepared. Next, in the same manner as in Example 2, each paste was screen-printed on one surface of the electrolyte layer and then baked. The firing temperature was set at three levels of 1200 ° C, 1350 ° C, and 1500 ° C. This obtained each sample which has each dense intermediate | middle layer (thickness 4 micrometers). And relative density was measured about each obtained sample.

  As shown in FIG. 8, it is possible to improve the sinterability of the dense intermediate layer by adding a sintering aid at any firing temperature. Therefore, the dense intermediate layer is easily formed densely. In particular, the effect is great when the additive amount of the sintering aid is 0.1 mol% or more. Moreover, since the effect will be saturated when the addition amount of a sintering aid exceeds 1 mol%, it turns out that 1 mol% or less is enough. Therefore, it can be said that an intermediate layer having the above structure can be easily obtained by adding a sintering aid to the raw material powder of the dense intermediate layer. In addition, the effect of improving the sinterability also appears at the interface between the dense intermediate layer and the porous intermediate layer, and can be said to contribute to the improvement of the bondability between the dense intermediate layer and the porous intermediate layer. . Therefore, it can be said that it is advantageous for improvement of power generation characteristics.

  The addition of the sintering aid did not significantly reduce the oxygen ion conductivity of the dense intermediate layer. In this example, a sintering aid containing Co is used. However, a sintering aid containing Ca, Mg, Cu, Fe, Ni, Zn, etc. is also equivalent to the sintering aid containing Co. have. Therefore, these sintering aids can also exhibit the above effects.

  Although the embodiments have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Electrolyte layer 3 Intermediate layer 4 Dense intermediate layer 5 Porous intermediate layer 6 Cathode layer 7 Anode layer 20 Sheet for electrolyte layer formation 201 Raw material powder of electrolyte layer 202 Organic material 40 Sheet for dense intermediate layer 401 Dense Organic intermediate material raw material 402 Organic material 41 Dense intermediate layer forming paste 401 Dense intermediate layer raw material powder 412 Organic material 51 Porous intermediate layer forming paste 501 Porous intermediate layer raw material powder 512 Organic material 11 Simultaneous firing Body 12 Laminated sintered body

Claims (9)

An electrolyte layer (2) formed of a solid electrolyte, a cathode layer (6) provided on one surface of the electrolyte layer (2) via an intermediate layer (3), and the other surface of the electrolyte layer (2) A fuel cell (1) having an anode layer (7) provided on the substrate,
The intermediate layer (3) is disposed on the electrolyte layer (2) side and is densely formed, and the cathode layer (6) of the dense intermediate layer (4). A porous intermediate layer (5) disposed on the side and formed more porous than the dense intermediate layer (4),
The fuel cell (1), wherein the dense intermediate layer (4) and the porous intermediate layer (5) are made of the same material. The fuel cell (1) according to claim 1,
The relative density of the dense intermediate layer (4) is 80% or more,
The fuel cell (1), wherein the porous intermediate layer (5) has a relative density in the range of 40 to 75%. The fuel cell (1) according to claim 1 or 2,
The total thickness of the intermediate layer (3) is 15 μm or less,
The fuel cell (1), wherein the thickness of the porous intermediate layer (5) is 2/3 or less of the total thickness of the intermediate layer (3). The fuel cell (1) according to any one of claims 1 to 3,
The fuel cell (1), wherein the intermediate layer (3) is formed of a cerium oxide-based oxide. The fuel cell (1) according to any one of claims 1 to 4,
The fuel cell (1), wherein the solid electrolyte is a zirconium oxide-based oxide or a lanthanum gallate-based oxide. The fuel cell (1) according to any one of claims 1 to 5, wherein the electrolyte layer (2), the dense intermediate layer (4) and the porous intermediate layer (5) A method for producing a laminated sintered body (12) including a laminated structure laminated in order,
On one surface of an unfired electrolyte layer forming sheet (20) formed into a sheet shape containing the raw material powder (201) and the organic material (202) of the electrolyte layer (2), the dense intermediate layer ( By laminating the unfired dense intermediate layer forming sheet (40) formed into a sheet shape containing the raw material powder (401) and the organic material (402) of 4), press-bonding, and co-firing Obtaining a co-fired body (11) comprising the electrolyte layer (2) and the dense intermediate layer (4) bonded to one surface of the electrolyte layer (2);
Porous intermediate layer forming paste containing raw powder (501) and organic material (512) of porous intermediate layer (5) on the surface of dense intermediate layer (4) of co-fired body (11) (51), and then firing at a temperature equal to or lower than the firing temperature at the time of the co-firing. A method for producing a laminated sintered body (12), comprising: The fuel cell (1) according to any one of claims 1 to 5, wherein the electrolyte layer (2), the dense intermediate layer (4) and the porous intermediate layer (5) A method for producing a laminated sintered body (12) including a laminated structure laminated in order,
A dense intermediate layer forming paste (41) containing the raw material powder (411) and the organic material (412) of the dense intermediate layer (4) on one surface of the electrolyte layer (2), the porous intermediate layer A laminated sintered body comprising a step of applying a porous intermediate layer forming paste (51) containing the raw material powder (501) and the organic material (512) of (5) in this order, followed by firing. (12) The manufacturing method. A method for producing a laminated sintered body (12) according to claim 6 or 7,
The average particle diameter d1 of the raw material powder (401) of the dense intermediate layer (4) and the average particle diameter d2 of the raw material powder (501) of the porous intermediate layer (5) satisfy the relationship of d1 <d2. A method for producing a laminated sintered body (12) characterized by the following. A method for producing a laminated sintered body (12) according to any one of claims 6 to 8,
The sintering aid containing one or more elements selected from Ca, Mg, Co, Cu, Fe, Ni and Zn in the raw material powder (401) of the dense intermediate layer (4) is 0. The method for producing a laminated sintered body (12), wherein the additive is added in the range of 1 to 1 mol%.

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