Method for manufacturing anode support cell

Abstract

To provide a manufacturing method of an anode support cell having high power generation characteristics.SOLUTION: In the production method of the present invention, a first laminate in which a layer containing an oxide represented by the composition formula La2Si2O7, a first layer located on one surface of the layer containing the oxide and containing cerium oxide doped with a lanthanum element, and a layer containing nickel oxide located on a side opposite to a surface facing the layer containing the oxide in the first layer are laminated is heated at 1000° C. or higher. A step of producing a solid electrolyte having an apatite structure and being c-axis oriented from the oxide, a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped or undoped with an Ln element (Ln represents a rare earth element other than cerium) on a side opposite to a surface facing the layer containing the cerium oxide in the layer containing the solid electrolyte, and a step of heating the second laminate at 1,000℃ or higher.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an anode-supported cell. [Background technology]

[0002] In recent years, fuel cells have been attracting attention as an approach to preventing global warming by reducing CO2 emissions. Among them, solid oxide fuel cells (SOFCs), which are made of ceramic materials, can operate at high temperatures and have the highest power generation efficiency among fuel cells. The solid electrolyte, which is the main component of SOFCs, is required to have high oxide ion conductivity.

[0003] For example, Patent Document 1 describes a manufacturing method for producing a new compound that conducts oxide ions at a bonding interface between multiple substances with different chemical compositions, with the aim of increasing the oxide ion conductivity of a solid electrolyte. According to this method, for example, by contacting a layer mainly composed of La2O3 with a layer mainly composed of La2Si2O7 and heating the resulting mixture, it is possible to produce a lanthanum silicate with its c-axis oriented along the thickness direction at the bonding interface.

[0004] Patent Document 2 describes a solid electrolyte junction including a solid electrolyte layer made of an oxide containing La, Si, and B, and a layer made of cerium oxide doped with La and Sm. The document also describes that in order to produce the solid electrolyte junction, a solid electrolyte layer and a layer containing cerium oxide doped with Sm are stacked together and heated at 1400°C, thereby obtaining high oxide ion conductivity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2012 / 015061 Brochure [Patent Document 2] International Publication No. 2019 / 203219 Brochure Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, a method for producing a solid electrolyte layer using element diffusion due to heating is known, but to obtain a solid electrolyte that can be used as a device using this method, a process is required to polish and remove unreacted layers that do not exhibit oxide ion conductivity from the produced solid electrolyte layer. Furthermore, the method described in Patent Document 2 requires that after obtaining a sintered body of the solid electrolyte, the cathode-side intermediate layer, the anode-side intermediate layer, the cathode, and the anode are heated under their respective conditions to produce a cell. Recently, in order to further increase the output of SOFCs, anode-supported cells have become mainstream, which allow for a thinner solid electrolyte by using anode materials to ensure mechanical strength. Anode-supported cells are generally obtained by co-sintering a thin solid electrolyte film with the anode material.

[0007] However, in the inventions described in Patent Documents 1 and 2, it was difficult to co-sinter the solid electrolyte material, which was manufactured by utilizing element diffusion due to heating, and the anode material. Furthermore, in the manufacturing process of an anode-supported cell in which only a single layer of the solid electrolyte is synthesized and then an intermediate layer and an electrode are formed, it was difficult to thin the solid electrolyte layer to withstand the process. [Means for solving the problem]

[0008] The present invention provides a method for producing a solid electrolyte having an apatite structure and a c-axis orientation from the oxides, by heating a first laminate including a layer containing an oxide represented by a composition formula La2Si2O7, a first layer containing cerium oxide doped with lanthanum and located on one side of the layer containing the oxide, and a layer containing nickel oxide and located on the side of the first layer opposite to the surface facing the layer containing the oxide, at 1000°C or higher; a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped with an Ln element (Ln represents a rare earth element other than cerium) or undoped on the surface of the layer containing the solid electrolyte opposite to the surface facing the layer containing cerium oxide; and heating the second laminate at 1000°C or higher; The above-mentioned problems are solved by providing a method for producing an anode-supported cell using the nickel oxide-containing layer having a thickness of 300 μm or more and 3000 μm or less.

[0009] The present invention also provides a method for producing a solid electrolyte having an apatite structure and a c-axis orientation from the oxides, by heating a first laminate including a layer containing an oxide represented by a composition formula La2SiO7, a first layer containing cerium oxide doped with lanthanum and located on one side of the layer containing the oxide, a layer containing nickel oxide and located on the side of the first layer opposite to the side facing the layer containing the oxide, and a preliminary support layer located on the side of the layer containing nickel oxide opposite to the side facing the first layer, at 1000°C or higher; a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped with an Ln element (Ln represents a rare earth element other than cerium) or undoped on the surface of the layer containing the solid electrolyte opposite to the surface facing the layer containing cerium oxide; and heating the second laminate at 1000°C or higher. [Effects of the Invention]

[0010] According to the method of the present invention, an anode-supported cell having high power generation properties can be produced. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a cross section along the thickness direction showing one embodiment of an anode support cell which is a target of the manufacturing method of the present invention. [Figure 2]FIG. 2 is a schematic cross-sectional view taken along the thickness direction, showing another embodiment of an anode support cell which is a target of the manufacturing method of the present invention. [Figure 3] FIG. 3 is an example of a scanning electron microscope image of a cross section along the thickness direction of the anode support cell shown in FIG. [Figure 4] FIG. 4 is an X-ray diffraction chart of the solid electrolyte layer of the anode support cells obtained in Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention relates to a method for manufacturing an anode-supported cell. The anode-supported cell is used in fuel cells such as SOFCs. In this specification, the term "anode-supported cell" encompasses (i) an embodiment in which the fuel electrode functions as the support layer, and (ii) an embodiment in which a support layer is provided separately from the fuel electrode. The manufacturing method of the present invention makes it possible to easily manufacture anode-supported cells of both embodiments.

[0013] The present invention will now be described based on preferred embodiments thereof with reference to the drawings. First, an anode-supported cell (i), which is one embodiment of an anode-supported cell manufactured by the method of the present invention, will be described with reference to FIG. 1 . The anode-supported cell 10 shown in the figure includes a layer 11 containing a solid electrolyte (hereinafter also referred to as a "solid electrolyte layer"). The solid electrolyte layer 11 is made of a material that exhibits oxide ion conductivity at a predetermined temperature or higher. The solid electrolyte layer 11 is located between two electrodes, namely, a cathode 12 and an anode 13. That is, the cathode 12 and the anode 13 are disposed on different sides of the solid electrolyte layer 11. The anode-supported cell of this embodiment includes the cathode 12, the solid electrolyte layer 11, and the anode 13 stacked in this order. The cathode 12 may be electrically connected to the negative electrode of a DC power supply (not shown). Meanwhile, the anode 13 may be electrically connected to the positive electrode of the DC power supply (not shown). Therefore, a DC voltage is applied between the cathode 12 and the anode 13.

[0014] A first intermediate layer 14 is disposed between the anode 13 and the solid electrolyte layer 11. Meanwhile, a second intermediate layer 15 is disposed between the cathode 12 and the solid electrolyte layer 11. In FIG. 1, the anode 13 and the first intermediate layer 14 are shown to have the same width, but the size relationship between them is not limited to this. For example, the anode 13 and the first intermediate layer 14 may have different sizes. The same applies to the cathode 12 and the second intermediate layer 15; they may have the same size, or, for example, the second intermediate layer 15 may be larger than the cathode 12. Furthermore, in FIG. 1, the first intermediate layer 14 and the solid electrolyte layer 11 are shown to have the same size, but the size relationship between them is not limited to this. For example, the solid electrolyte layer 11 and the first intermediate layer 14 may have different sizes. The same applies to the cathode 12 side.

[0015] 1, the first intermediate layer 14 is in direct contact with the anode 13 and the solid electrolyte layer 11. Therefore, no layer is interposed between the first intermediate layer 14 and the anode 13. The first intermediate layer 14 is also in direct contact with the solid electrolyte layer 11, with no layer interposed between them. The same is true on the cathode 12 side, where the second intermediate layer 15 is in direct contact with the solid electrolyte layer 11 and the cathode 12.

[0016] The first intermediate layer 14 and the second intermediate layer 15 (hereinafter, for convenience, they may be collectively referred to simply as "intermediate layer 16") are used for the purpose of improving the oxide ion conductivity between the solid electrolyte layer 11 and the air electrode 12 and / or the anode electrode 13 in the anode support cell 10. Increasing the oxide ion conductivity of the solid electrolyte layer 11 is important to reduce the electrical resistance of the anode support cell 10. However, even if the solid electrolyte layer 11 is made of a material with high oxide ion conductivity, if the oxide ion conductivity between the solid electrolyte layer 11 and the anode electrode 13 and / or the air electrode 12 is low, there is a limit to how much the oxide ion conductivity of the anode support cell 10 as a whole can be improved. As a result of studies by the present inventors, it has been found that when the air electrode 12, the anode electrode 13, the solid electrolyte layer 11, and the intermediate layer 16 contain the same rare earth element (hereinafter, also referred to as a "common rare earth element"), the oxide ion conductivity of the anode support cell 10 as a whole is improved, resulting in high power generation characteristics. The reason for this is unclear, but the present inventors believe it to be as follows. However, we are not bound by this theory. The air electrode 12 and the fuel electrode 13 in the anode support cell 10 are, for example, a compound represented by the general formula: ABO 3‐δ The inventors believe that this is because, when the cathode 12 and the anode 13 contain the same or different oxides represented by the general formula: ABO, a common rare earth element is located in part of the A site, forming a path in the oxide that facilitates the movement of oxide ions. 3‐δ The present inventors believe that the pathway is more likely to form when the common rare earth element is lanthanum, and that the pathway is particularly likely to form when the common rare earth element is lanthanum.

[0017] To enhance the effect of the common rare earth element, the common rare earth element is preferably lanthanum. Furthermore, to improve the oxide ion conductivity of the anode support cell 10, it is preferable that the air electrode 12, the anode 13, the solid electrolyte layer 11, and the intermediate layer 16 all contain an oxide. In summary, it is preferable that the air electrode 12, the anode 13, the solid electrolyte layer 11, and the intermediate layer 16 all contain an oxide of the common rare earth element. The solid electrolyte layer 11, the intermediate layer 16, the fuel electrode 13, and the air electrode 12 will be described in detail below.

[0018] The solid electrolyte layer 11 is a conductor in which oxide ions serve as carriers. A single crystal or polycrystalline material is used as the solid electrolyte contained in the solid electrolyte layer 11. In particular, it is preferable to use an oxide of a common rare earth element as the solid electrolyte, since this further increases the oxide ion conductivity. In order to further increase the oxide ion conductivity of the anode support cell 10, the solid electrolyte preferably contains a composite oxide.

[0019] When the common rare earth element is lanthanum, examples of the oxide of the common rare earth element include a composite oxide containing lanthanum and silicon, a composite oxide containing lanthanum and gallium, a composite oxide in which strontium, magnesium, cobalt, or the like is added to a composite oxide containing lanthanum and gallium, and a composite oxide containing lanthanum and molybdenum. Alternatively, when the common rare earth element is samarium, examples of the oxide of the common rare earth element include a composite oxide containing samarium and cerium. Among these oxides of common rare earth elements, it is preferable to use an oxide ion conductive material made of a composite oxide of lanthanum and silicon, from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and enhancing the power generation characteristics of the anode support cell 10.

[0020] The above-mentioned composite oxide of lanthanum and silicon includes, for example, an apatite-type composite oxide containing lanthanum and silicon and having an apatite-type crystal structure. The apatite-type composite oxide contains lanthanum, which is a trivalent element, silicon, which is a tetravalent element, and O, and has a composition represented by the general formula: La x SiO 1.5x+12(X is a number of 8 or more and 10 or less) is preferred from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and enhancing the power generation characteristics of the anode support cell 10. The most preferred composition of this apatite-type composite oxide is La 9.33 SiO 26 When this apatite-type composite oxide is used as a solid electrolyte, it is preferable that the c-axis coincides with the thickness direction of the solid electrolyte layer 11. This composite oxide can be produced, for example, according to the method described in JP 2013-51101 A.

[0021] Another example of a solid electrolyte is a solid electrolyte having the general formula: A 9.33+x [T 6.00 ]O 26.00+z Examples of the composite oxide include a composite oxide represented by the formula: This composite oxide also has an apatite-type crystal structure. In the formula, A is one or more elements selected from the group consisting of La, Ce, Nd, and Sm. In the formula, T is Si. From the viewpoint of enhancing the c-axis orientation, A is preferably one or more elements selected from the group consisting of La, Ce, and Sm.

[0022] In the formula, x is preferably -1.33 or more and 3.00 or less, more preferably 0.00 or more and 2.50 or less, and even more preferably 0.45 or more and 1.50 or less, from the viewpoint of increasing the degree of orientation and oxide ion conductivity. In the formula, z is preferably -5.00 or more and 5.20 or less, more preferably -2.00 or more and 1.50 or less, and even more preferably -1.00 or more and 1.00 or less, from the viewpoint of maintaining electrical neutrality in the apatite-type crystal lattice.

[0023] In the above formula, the ratio of the number of moles of A to the number of moles of T (A / T), in other words, (9.33+x) / (6.00) in the above formula, is preferably 1.33 or more and 3.61 or less, more preferably 1.40 or more and 3.00 or less, and even more preferably 1.50 or more and 2.00 or less, from the viewpoint of maintaining the spatial occupancy rate in the apatite-type crystal lattice.

[0024] Among the composite oxides represented by the above formula, it is preferable to use a composite oxide in which A contains lanthanum from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and from the viewpoint of enhancing the power generation characteristics of the anode support cell 10. Specific examples of the composite oxide in which A contains lanthanum include, for example, (La a Sm b Ce c ) 9.33+x [Si 6.00 O 26.00 (0.95 < a + b + c < 1.05. ), (La a Ce b ) 9.33+z [Si 6.00 O 26.00 (0.95 < a + b < 1.05. ), (La a Sm b ) 9.33+x [Si 6.00 O 26.00 ((La a Nd b Sm c ) 9.33+x [Si 6.00 O 26.00+z (0.95 < a + b + c < 1.05. ), and (La a Nd b ) 9.33+x [Si 6.00 O 26.00+z (0.95 < a + b < 1.05. ) and the like. The composite oxide represented by the above formula can be produced, for example, according to the method described in International Publication WO2016 / 111110.

[0025] The content ratio of the metal elements in the solid electrolyte layer 11 can be measured, for example, by energy dispersive X-ray spectroscopy (EDS). The same applies to the content ratio of the metal elements contained in the layers other than the solid electrolyte layer 11 constituting the anode support cell 10.

[0026] When the anode support cell 10 is manufactured by the manufacturing method described below, the solid electrolyte contained in the solid electrolyte layer 11 has particularly excellent c-axis orientation, and the oxide ion conductivity of the solid electrolyte layer 11 is improved. In this specification, "c-axis oriented" means that, when the apatite-type composite oxide is a polycrystalline body, the crystal axes are aligned along the c-axis. Furthermore, when the apatite-type composite oxide exists in the form of a single crystal, the c-axis direction can be made to coincide with the oxide ion conduction direction in the anode support cell 10.

[0027] The c-axis orientation of the solid electrolyte can be confirmed by the fact that the degree of c-axis orientation f calculated based on the following formula (1) is preferably 0.50 or more, more preferably 0.60 or more, and even more preferably 0.65 or more. The higher the ratio, the better, but in reality it is, for example, 0.99 or less.

[0028] The degree of c-axis orientation (f) of a solid electrolyte can be calculated by the Rotterdam method. Specifically, the degree of c-axis orientation (f) can be calculated based on the following formula (1) using the ratio ρ of the sum of the peak intensities (ΣI(001)) attributable to the (002) and (004) planes of the solid electrolyte to the sum of all peak intensities (ΣI(hkl)) obtained by X-ray diffraction (hereinafter also referred to as "XRD") of the solid electrolyte. The reason for using the (002) and (004) planes is that the peaks attributable to the (002) and (004) planes are unique to c-axis orientation and are independent peaks that do not overlap with the diffraction angle values ​​attributable to other planes. c-axis orientation f=(ρ-ρ0) / (1-ρ0) ···(1) Here, in the formula (1), ρ0 and ρ have the following values. ρ0: theoretical value ρ0=ΣI0(001) / ΣI0(hkl) ρ: measured value ρ=ΣI(001) / ΣI(hkl)

[0029] Alternatively, the c-axis orientation of the solid electrolyte can be confirmed by determining that the proportion of crystals with a deviation angle of 20 degrees or less from the c-axis orientation of the solid electrolyte, as measured by EBSD crystal orientation analysis, is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. The higher the proportion, the better, but in reality, it is, for example, 90% or less.

[0030] The thickness of the solid electrolyte layer 11 is preferably 10 nm or more, more preferably 100 nm or more, and even more preferably 1000 nm or more, from the viewpoint of effectively reducing the electrical resistance of the anode supported cell 10. From the same viewpoint, the thickness is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. The thickness of the solid electrolyte layer 11 can be measured using, for example, a stylus step gauge or an electron microscope.

[0031] As described above, the intermediate layer 16 is a layer that improves the oxide ion conductivity of the solid electrolyte layer 11. From the viewpoint of making this effect more pronounced, the intermediate layer 16 is made of cerium oxide containing lanthanum and Ln element (Ln represents a rare earth element other than cerium) (hereinafter referred to as "La-Ln 1 In this case, the rare earth elements other than cerium are common rare earth elements. 1 DC is an oxide in which rare earth elements other than cerium are doped into the base material cerium oxide (CeO2). The doped rare earth elements typically exist in the cerium oxide crystal lattice by substituting for the cerium site. Lanthanum exists in the cerium oxide solid solution. That is, lanthanum can exist in the cerium oxide crystal lattice by substituting for the cerium site, or it can exist at the grain boundaries of cerium oxide doped with Ln.

[0032] La-Ln constituting the intermediate layer 16 1In DC, examples of the Ln element to be doped into cerium oxide include La, Nd, Sm, Gd, Y, Er, Yb, and Dy. These Ln elements may be used singly or in combination of two or more. In other words, the intermediate layer 16 may be configured to contain cerium oxide in which the Ln element is at least one selected from the group consisting of La, Nd, Sm, Gd, Y, Er, Yb, and Dy. In particular, it is preferable that the intermediate layer 16 be configured to contain cerium oxide in which the Ln element is at least one selected from the group consisting of La, Nd, and Sm, from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and thereby further improving the oxide ion conductivity of the entire anode support cell 10. Note that the La-Ln element constituting both intermediate layers 14 and 15 1 The DC may be the same or different. 1 One may be composed of DC and the other may be composed of another substance.

[0033] La-Ln 1 In DC, the ratio of Ln element doped in cerium oxide is 1 ) is the atomic ratio of Ln 1 The doping degree of Ln element is preferably 0.050 or more and 0.50 or less, more preferably 0.10 or more and 0.40 or less, and even more preferably 0.20 or more and 0.30 or less, expressed in terms of Ln / Ce. By setting the doping degree of Ln element within this range, the oxide ion conductivity between the solid electrolyte layer 11 and the air electrode 12 and / or the fuel electrode 13 is improved.

[0034] The above Ln 1 The value of / Ce is measured by energy dispersive X-ray spectroscopy (EDS) and electron probe microanalyzer (EPMA), etc. Furthermore, the presence of Ln element in cerium oxide as a solid solution is confirmed by X-ray diffraction.

[0035] La-Ln constituting the first intermediate layer 14 1In DC, lanthanum is contained for the purpose of further improving the oxide ion conductivity of the solid electrolyte layer 11, thereby further improving the oxide ion conductivity of the entire anode support cell 10. For this purpose, La-Ln 1 In DC, the atomic ratio of lanthanum to cerium, La / Ce, is preferably 0.10 or more. Furthermore, if the amount of lanthanum is too much, the oxide ion conductivity decreases, so it is preferably 1.2 or less. From these viewpoints, the La / Ce value is more preferably 0.20 or more and 1.0 or less, and even more preferably 0.25 or more and 0.80 or less. The La / Ce value is measured by energy dispersive X-ray spectroscopy (EDS), electron probe microanalyzer (EPMA), or the like.

[0036] The inventors' investigations have revealed that the oxide ion conductivity between the solid electrolyte layer 11 and the air electrode 12 and / or the anode 13 can be effectively improved by providing the intermediate layer 16 with a predetermined thickness. Specifically, the thickness of the intermediate layer 16 is preferably 10 nm or more, more preferably 100 nm or more, and even more preferably 1 μm or more, for each of the first intermediate layer 14 and the second intermediate layer 15. For the same reasons, the thickness is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. The thickness of the intermediate layer 16 can be measured using a stylus profilometer, an electron microscope, or the like. The thickness of the first intermediate layer 14 and the thickness of the second intermediate layer 15 may be the same or different.

[0037] The fuel electrode 13 of this embodiment functions not only as an electrode but also as a support layer that enhances the mechanical strength of the anode support cell 10. For this purpose, the fuel electrode 13 is relatively thicker than a typical electrode. The anode support cell 10 has such a fuel electrode 13, which enhances the mechanical strength of the anode support cell 10. This allows the thicknesses of the air electrode 12, solid electrolyte layer 11, and intermediate layer 16 to be smaller than in the case of a typical electrode, which has a relatively thin electrode. As a result, this embodiment provides an anode support cell 10 that has excellent mechanical strength and durability and in which a decrease in oxide ion conductivity is suppressed.

[0038] To make the above-mentioned effects more pronounced, the thickness of fuel electrode 13 is preferably 300 μm or more, more preferably 750 μm or more, and even more preferably 1000 μm or more. From the same viewpoint, the thickness of fuel electrode 13 is preferably 3000 μm or less, more preferably 2500 μm or less, and even more preferably 2000 μm or less. The thickness of the fuel electrode 13 can be measured using a stylus step gauge, an electron microscope, or the like.

[0039] As described above, the air electrode 12 and the anode 13, which are disposed in direct contact with the intermediate layer 16, preferably contain an oxide containing a common rare earth element and having oxide ion conductivity. In addition, the air electrode 12 and the anode 13 may each independently further contain a metal material. Because of advantages such as high catalytic activity, the metal material preferably contains nickel or a platinum group element, and nickel is more preferred. Examples of platinum group elements include platinum, ruthenium, rhodium, palladium, osmium, and iridium. These elements can be used alone or in combination. Alternatively, the anode 13 and the air electrode 12 can each independently be a cermet containing an oxide containing a common rare earth element and the metal material.

[0040] The oxide contained in the air electrode 12 and the fuel electrode 13 is an oxide having the general formula: ABO 3-δ The oxides having a perovskite structure represented by the formula (hereinafter also referred to as "oxide a") are preferably used. In the formula, A represents an alkaline earth metal element, some of which contain common rare earth elements. In the formula, B represents a transition metal element, such as Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Ta, and W. In the formula, δ is a fraction resulting from the valence and amount of A, B, and O. General formula: ABO 3-δ Various oxides having a perovskite structure represented by the formula (I) are known, and it is known that such oxides have various crystal systems, such as cubic, tetragonal, rhombohedral, and orthorhombic systems. Among these crystal systems, ABO oxides having a cubic perovskite structure are 3-δ It is preferable to use an oxide of this type as the air electrode 12 and / or the fuel electrode 13. By directly bonding the air electrode 12 and / or the fuel electrode 13 made of such an oxide to the intermediate layer 16 made of the above-mentioned material to form the anode support cell 10, the oxide ion conductivity of the anode support cell 10 as a whole can be further improved.

[0041] The content of the common rare earth element in oxide a, expressed as the atomic ratio of lanthanum to all elements located at the A site, is preferably 0.010 to 0.80, more preferably 0.050 to 0.80, even more preferably 0.10 to 0.70, even more preferably 0.15 to 0.70, and most preferably 0.15 to 0.60. By ensuring that the content of the common rare earth element in oxide a falls within the above range, the oxide ion conductivity of oxide a can be improved. While the reason for this is unclear, the present inventors believe that the inclusion of a common rare earth element in part of the A site forms a path in oxide a that facilitates the migration of oxide ions. However, the present inventors are not bound by this theory.

[0042] Whether or not a common rare earth element is located in part of the A site in oxide a can be confirmed by X-ray diffraction. The proportion of lanthanum in all elements located in the A site can be measured by energy dispersive X-ray spectroscopy (EDS), electron probe microanalyzer (EPMA), ICP optical emission spectroscopy, etc.

[0043] When oxide a is used as the material constituting the air electrode 12, it is preferable that the alkaline earth metal element occupying the A site be at least one selected from the group consisting of barium and strontium, from the viewpoint of improving the oxide ion conductivity of the entire anode support cell 10. In other words, it is preferable that at least lanthanum and at least one element selected from the group consisting of barium and strontium are located at the A site of oxide a.

[0044] A portion of the transition metal elements occupying the B sites of oxide a preferably includes at least one element belonging to the fourth and fifth periods of the periodic table. In particular, the transition metal elements located at the B sites preferably include at least one element selected from the group consisting of iron, cobalt, nickel, copper, titanium, zirconium, and niobium, and it is even more preferable that at least a portion of the transition metal elements be iron, from the viewpoint of improving the oxide ion conductivity of the anode support cell 10 as a whole. From the same viewpoint, it is particularly preferable that at least a portion of the B sites be both iron and copper.

[0045] When iron is located at the B site of oxide a, from the viewpoints of improving the oxide ion conductivity of the anode support cell 10 as a whole and not affecting the crystal system of oxide a, the atomic ratio of iron to all elements located at the B site is preferably 0.05 to 0.95, more preferably 0.10 to 0.90, and even more preferably 0.20 to 0.80. Furthermore, when iron and copper are located at the B site of oxide a, the total atomic ratio of iron and copper to all elements located at the B site is preferably 0.80 to 1.00, more preferably 0.85 to 1.00, and even more preferably 0.90 to 1.00. In this case, the atomic ratio of iron to copper, Fe / Cu, is preferably 1.00 to 10.0, more preferably 2.00 to 9.50, and even more preferably 5.00 to 9.00. The atomic ratio and the Fe / Cu value can be measured by energy dispersive X-ray spectroscopy (EDS), electron probe microanalyzer (EPMA), ICP optical emission spectroscopy, etc. Whether iron is located at the B site in oxide a can be confirmed by X-ray diffraction.

[0046] The oxide a preferably has the general formula: La 1-x A x BO 3-δ In the formula, A is an element containing Ba or Sr, or both. In the formula, B is one or more elements selected from the group consisting of Fe, Cu, Ti, Zr, and Nb. In particular, B is preferably one or more elements selected from the group consisting of Fe, Cu, and Zr. In the formula, x is a number between 0.01 and 0.80.

[0047] Particularly preferred oxides as oxide a are those shown in (i) to (iv) below. (i) An oxide in which the A site is occupied by lanthanum and strontium, and the B site is occupied by iron and cobalt. (ii) Oxides in which the A-site is occupied by lanthanum and strontium and the B-site is occupied by iron, cobalt, and nickel. (iii) Oxides in which the A site is occupied by lanthanum and barium and the B site is occupied by iron. (iv) Oxides in which the A site is occupied by lanthanum and barium and the B site is occupied by iron and copper.

[0048] Oxide a can be obtained by a breakdown method, which uses mechanical energy to reduce particle size, or a build-up method, which uses chemical reactions to control the growth of atomic or molecular aggregates. The build-up method is preferred from the perspective of reducing electrical resistance. The build-up method is believed to produce the aforementioned effects because it facilitates the production of fine particles and increases the contact area between particles. Specifically, oxide a can be obtained, for example, by the following method. Specifically, acetates or nitrates of metals mixed in a stoichiometric ratio according to the composition of the desired oxide having a perovskite structure and DL-malic acid are dissolved in ion-exchange water, and ammonia water is added while stirring to adjust the pH to 5-6. The solution is then evaporated at 350°C, and the resulting powder is pulverized in a mortar. The resulting powder is then calcined in air at 700°C to 1000°C for 5 hours and pulverized again. However, the method for producing oxide a is not limited to this method.

[0049] Suitable oxides contained in the air electrode 12 and the fuel electrode 13 include the oxide a, as well as the above-mentioned La-Ln 1 DC can also be exemplified. 1 For DC, La-Ln included in the middle layer 16 1 Since the above explanation about DC applies, the following will be used to explain La-Ln 1 Only the differences from DC will be explained.

[0050] La-Ln 1 When DC is contained in the fuel electrode 13, the value of La / Ce, which is the atomic ratio of lanthanum to cerium, is preferably 0.1 or more and 1.2 or less, more preferably 0.2 or more and 1.0 or less, and even more preferably 0.25 or more and 0.8 or less.

[0051] In particular, from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and thereby further improving the oxide ion conductivity of the anode support cell 10 as a whole, it is preferable that the fuel electrode 13 contains cerium oxide in which the Ln element is at least one selected from the group consisting of La, Nd, Sm, Gd, Y, Er, Yb, and Dy. Also, from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and thereby further improving the oxide ion conductivity of the anode support cell 10 as a whole while enhancing the catalytic activity of the fuel electrode, the fuel electrode 13 is preferably made of La-Ln 1 More preferably, it comprises a cermet of DC and nickel.

[0052] When the fuel electrode 13 contains an oxide containing a common rare earth element (hereinafter also referred to as the "first oxide") and the solid electrolyte in the solid electrolyte layer 11 contains an oxide containing a common rare earth element (hereinafter also referred to as the "second oxide"), it is preferable that the content of the common rare earth element in the first oxide and the content of the common rare earth element in the second oxide have a predetermined relationship. Specifically, the ratio of the number of moles of the common rare earth element to the total number of moles of elements other than oxygen in the first oxide is defined as n1, and the ratio of the number of moles of the common rare earth element to the total number of moles of elements other than oxygen in the second oxide is defined as n2. In this case, the ratio n1 / n2 is preferably 0.30 or more, more preferably 0.35 or more, and even more preferably 0.40 or more. Furthermore, n1 / n2 is preferably 0.70 or less, more preferably 0.60 or less, and even more preferably 0.55 or less. By setting n1 / n2 within the above range, the oxide ion conductivity of the solid electrolyte layer 11 is further improved, and as a result, the oxide ion conductivity of the anode support cell 10 as a whole is further improved, thereby improving the power generation characteristics of the anode support cell 10. In addition, when the anode contains a cermet of the first oxide and a metallic material, the number of moles of the metallic element contained in the metallic material is not included in the "total number of moles of elements other than oxygen" used in calculating n1. The same applies to the calculation of n2 and n3 to n6 described below.

[0053] Furthermore, from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11, thereby further improving the oxide ion conductivity of the anode support cell 10 as a whole, and enhancing the power generation characteristics of the anode support cell 10, n1 is preferably 8.0 mol % or more and 50 mol % or less, more preferably 9.0 mol % or more and 45 mol % or less, and even more preferably 10 mol % or more and 40 mol % or less. From the same viewpoint, n2 is preferably 45 mol % or more and 80 mol % or less, more preferably 50 mol % or more and 75 mol % or less, and even more preferably 55 mol % or more and 70 mol % or less.

[0054] From a similar viewpoint, when the air electrode 12 contains an oxide containing a common rare earth element, the ratio n3 of the number of moles of the common rare earth element to the total number of moles of elements other than oxygen in the oxide is preferably 20 mol% or more and 40 mol% or less, more preferably 25 mol% or more and 38 mol% or less, and even more preferably 30 mol% or more and 35 mol% or less. Furthermore, when the second intermediate layer 15 contains an oxide containing a common rare earth element, the ratio n4 of the number of moles of the common rare earth element to the total number of moles of elements other than oxygen in the oxide is preferably 3 mol% or more and 27 mol% or less, more preferably 5 mol% or more and 25 mol% or less, and even more preferably 6 mol% or more and 20 mol% or less. Furthermore, when the first intermediate layer 14 contains an oxide containing a common rare earth element, the ratio n5 of the number of moles of the common rare earth element to the total number of moles of elements other than oxygen in the oxide is preferably 3 mol% or more and 50 mol% or less, more preferably 10 mol% or more and 40 mol% or less, and even more preferably 15 mol% or more and 35 mol% or less. In the anode support cell 10 of this embodiment, only one of n1 to n5 may be within the above-mentioned preferred numerical range, or any combination of two or more may be within the above-mentioned preferred numerical range.

[0055] From the viewpoint of increasing the oxide ion conductivity of the anode support cell 10 as a whole and improving the power generation characteristics of the anode support cell 10, the ratio of n4 to n2, n4 / n2, is preferably 0.001 or more, more preferably 0.005 or more, even more preferably 0.01 or more, and still more preferably 0.08 or more. From the same viewpoint, n4 / n2 is preferably 0.6 or less, more preferably 0.45 or less, even more preferably 0.3 or less, and still more preferably 0.2 or less. From the viewpoint of increasing the oxide ion conductivity of the anode support cell 10 as a whole and improving the power generation characteristics of the anode support cell 10, the ratio of n5 to n2, n5 / n2, is preferably 0.070 or more, more preferably 0.20 or more, and even more preferably 0.27 or more. From the same viewpoint, n5 / n2 is preferably 0.70 or less, more preferably 0.65 or less, and even more preferably 0.60 or less.

[0056] From the viewpoint of reducing electrical resistance, the average particle diameter of the oxide contained in the air electrode 12 and the anode 13 is preferably 1000 nm or less, more preferably 600 nm or less, even more preferably 300 nm or less, and even more preferably 200 nm or less. From the same viewpoint, the average particle diameter of the oxide contained in the air electrode 12 and the anode 13 is preferably 1 nm or more, more preferably 2 nm or more, and even more preferably 3 nm or more. The average particle diameter can be calculated using images of particles obtained by observation with a scanning electron microscope and known image analysis software. For example, the outlines of 10 randomly selected particles are observed at 1000 to 100,000 magnifications to determine the particle contours. If necessary, processing such as contrast enhancement or drawing lines along the contours can be performed, and the average particle diameter can be calculated by image analysis.

[0057] It is preferable that the air electrode 12 have a predetermined thickness, from the viewpoint of further improving the oxide ion conductivity of the solid electrolyte layer 11 and thereby more effectively improving the oxide ion conductivity of the anode support cell 10 as a whole. Specifically, the thickness of the air electrode 12 bonded to the intermediate layer 16 is preferably 100 nm or more, more preferably 200 nm or more, even more preferably 500 nm or more, even more preferably 1 μm or more, and particularly preferably 5 μm or more. From the same viewpoint, the thickness of the air electrode 12 is preferably 25 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and even more preferably 10 μm or less. The thickness of the air electrode 12 can be measured using a stylus profilometer, an electron microscope, or the like.

[0058] Next, an anode support cell (ii), which is another embodiment of the anode support cell produced by the method of the present invention, will be described with reference to Fig. 2. Regarding the embodiment of the anode support cell shown in Fig. 2, the configuration different from the anode support cell 10 shown in Fig. 1 will be mainly described, and the same components as those in the anode support cell 10 will be assigned the same reference numerals and will not be described again. For the configuration not specifically described in the embodiment of the anode support cell shown in Fig. 2, the description of the anode support cell 10 shown in Fig. 1 applies as appropriate.

[0059] The anode-supported cell 10 shown in FIG. 2 further includes a support layer 17 in addition to the fuel electrode 13. The support layer 17 is located on the side of the fuel electrode 13 opposite the surface facing the solid electrolyte layer 11. The support layer 17 is in direct contact with the fuel electrode 13. Therefore, no layer is interposed between the support layer 17 and the fuel electrode 13. In FIG. 2, the support layer 17 and the fuel electrode 13 are shown to have the same width, but the size relationship between the two is not limited to this. For example, the support layer 17 and the fuel electrode 13 may have different sizes. For example, the size relationship may be such that the support layer 17 extends from the periphery of the fuel electrode 13.

[0060] The support layer 17 is a layer that functions to enhance the mechanical strength of the anode support cell 10. In the anode support cell 10 shown in FIG. 1 , the anode 13 performs this function. However, in the anode support cell 10 of this embodiment, the support layer 17 is provided separately from the anode 13. Therefore, in the anode support cell 10 of this embodiment, the thickness of the anode 13 can be made smaller than in the anode support cell 10 shown in FIG. 1 . The anode support cell 10 having such a support layer 17 can enhance the mechanical strength of the anode support cell 10. As a result, the thicknesses of the air electrode 12, the anode 13, the solid electrolyte layer 11, and the intermediate layer 16 can be made smaller than in a case where the support layer 17 is not provided. As a result, the anode support cell 10 of this embodiment has excellent mechanical strength and durability and is prevented from decreasing in oxide ion conductivity.

[0061] To make the above-mentioned effects more pronounced, the thickness of the support layer 17 is preferably 200 μm or more, more preferably 300 μm or more, even more preferably 500 μm or more, and even more preferably 1000 μm or more. From the same viewpoint, the thickness of the support layer 17 is preferably 3000 μm or less, more preferably 2500 μm or less, and even more preferably 2000 μm or less. In this embodiment, in which a support layer 17 is provided on the anode support cell 10, the thickness of the fuel electrode 13 can be made smaller than that of the embodiment shown in Figure 1. Specifically, the thickness of the fuel electrode 13 can be made 30 µm or less, more preferably 25 µm or less, even more preferably 20 µm or less, even more preferably 15 µm or less, and particularly preferably 10 µm or less. The thickness of the fuel electrode 13 can be made 0.2 µm or more, more preferably 0.5 µm or more, and even more preferably 1.0 µm or more. The thickness of the support layer 17 can be measured using a stylus step gauge, an electron microscope, or the like.

[0062] Fig. 3 shows an example of a scanning electron microscope (SEM) image of a cross section along the thickness direction of the anode support cell 10. In Fig. 3, the boundaries between the layers of the anode support cell 10 are clearly observed. Therefore, by using the SEM image, it is possible to measure the thickness of each layer of the anode support cell 10.

[0063] Support layer 17 preferably contains the common rare earth element. In anode support cell 10, solid electrolyte layer 11 and support layer 17 both contain the common rare earth element, making it easy to control the linear expansion coefficients of solid electrolyte layer 11 and support layer 17 to similar values. As a result, when anode support cell 10 is used, cracking of solid electrolyte layer 11 due to the difference between the linear expansion coefficients can be suppressed.

[0064] When support layer 17 contains an oxide containing the aforementioned common rare earth element, the ratio n6 of the number of moles of the common rare earth element to the total number of moles of elements other than oxygen in the oxide is preferably within a predetermined range. Specifically, from the viewpoint of further improving the oxide ion conductivity of solid electrolyte layer 11, thereby further improving the oxide ion conductivity of anode support cell 10 as a whole and enhancing the power generation characteristics of anode support cell 10, n6 is preferably 9 mol% to 80 mol%, more preferably 10 mol% to 75 mol%, even more preferably 12 mol% to 70 mol%, still more preferably 30 mol% to 70 mol%, particularly preferably 40 mol% to 70 mol%, and even more preferably 45 mol% to 65 mol%. In the anode support cell 10 of this embodiment, only one of the above-mentioned n1 to n5 and n6 may be within the above-mentioned preferred numerical range, or any combination of two or more of them may be within the above-mentioned preferred numerical range.

[0065] The oxide containing the common rare earth element contained in the support layer 17 may be, for example, any of the oxides exemplified above as solid electrolytes. In addition, the support layer 17 may further contain a metal material. From the viewpoint of high catalytic activity and electron conductivity, the metal material is preferably nickel or a platinum group element, and more preferably nickel. Alternatively, the support layer 17 may be a cermet containing the oxide exemplified above as a solid electrolyte and the metal material. From the viewpoint of suppressing an increase in electrical resistance during current collection, it is preferable that the support layer 17 be conductive.

[0066] Next, a manufacturing method of the present invention will be described. The manufacturing method of the present invention includes the steps of preparing a first laminate, which is a layer of a raw material composition, and heating the first laminate at a predetermined temperature; obtaining a second laminate in which a layer of the raw material composition is disposed on a sintered body of the first laminate; and heating the second laminate at a predetermined temperature. According to the present invention, most of the anode-supported cell can be manufactured by heating a laminate consisting of several types of layers. Therefore, the anode-supported cells of the above-mentioned embodiments (i) and (ii) can be manufactured more easily than conventional manufacturing methods that require heating each layer separately.

[0067] First, (i) a method for manufacturing an anode-supported cell in which the fuel electrode functions as a support layer will be described. A green sheet can be suitably used for the first laminate. The green sheet can be obtained by forming a slurry containing a raw material composition for the anode support cell into a sheet shape. First, as the raw material compositions, a raw material composition used for producing the solid electrolyte, a raw material composition used for producing the first intermediate layer, and a raw material composition used for producing the fuel electrode are prepared.

[0068] The raw material composition used to produce the solid electrolyte contains lanthanum and silicon. For example, an oxide represented by the composition formula La2Si2O7 can be prepared as such a raw material composition.

[0069] The raw material composition used to manufacture the first intermediate layer contains the common rare earth element, cerium, and oxygen. In this raw material composition, the common rare earth element is preferably lanthanum, from the viewpoint of further improving the oxide ion conductivity of the anode support cell as a whole and enhancing the power generation characteristics of the anode support cell. From the same viewpoint, this raw material composition is preferably doped with lanthanum. As such a raw material composition, for example, 0.5 Ce 0.5 O 1.75 A compound represented by the formula:

[0070] The raw material composition used to manufacture the anode contains the common rare earth elements, nickel, and oxygen. The nickel in the raw material composition functions as a catalyst for the reaction. For example, nickel (II) oxide and cerium oxide doped or undoped with Ln (Ln represents a rare earth element other than Ce) can be prepared as such a raw material composition. Specifically, a composition having the composition formula La 0.5 Ce 0.5 O 1.75 A compound represented by the formula:

[0071] Once the above raw material compositions are prepared, one of the raw material compositions is mixed with water and a liquid such as an organic solvent to prepare a slurry of the raw material composition. A slurry is prepared for each of the raw material compositions for the solid electrolyte, the first intermediate layer, and the anode. Examples of organic solvents that can be used include ethanol, isopropyl alcohol, and toluene. These organic solvents can be used alone or in combination. Mixing can be performed using, for example, an ultrasonic homogenizer, a shaker, a thin film rotary mixer, a dissolver, a homomixer, a kneader, a roll mill, a sand mill, an attritor, a ball mill, a vibrator mill, and a high-speed impeller mill. During mixing, additives such as a dispersant, an antifoaming agent, a binder, and a plasticizer can be used as needed. The mixing time and temperature are not particularly limited and can be adjusted appropriately depending on the type of raw material composition and liquid.

[0072] Once the slurry is prepared, it is formed into a sheet to obtain a green sheet. Forming is performed for each of the solid electrolyte, first intermediate layer, and anode slurries. As a result, a layer containing an oxide (hereinafter simply referred to as the "oxide layer") is obtained from the solid electrolyte slurry. The first intermediate layer slurry is obtained from the first layer. The anode slurry is obtained from the nickel oxide-containing layer (hereinafter simply referred to as the "nickel oxide layer"). The molding can be carried out using various molding machines such as a film applicator, a doctor blade, a spray or a spin coater.

[0073] Each layer is preferably formed to have a predetermined thickness, from the viewpoint of successfully obtaining a desired anode support cell by heating the first laminate described below. Specifically, the oxide layer preferably has a thickness of 5 μm or more, more preferably 10 μm or more. From the same viewpoint, the oxide layer preferably has a thickness of 40 μm or less, more preferably 30 μm or less. From the viewpoint of successfully obtaining a desired anode-supported cell, the thickness of the first layer is preferably 10 μm or more, more preferably 15 μm or more, and from the same viewpoint, the thickness of the first layer is preferably 100 μm or less, more preferably 80 μm or less. From the viewpoint of successfully obtaining a desired anode support cell, the nickel oxide layer preferably has a thickness of 300 μm or more, more preferably 750 μm or more, and from the same viewpoint, the nickel oxide layer preferably has a thickness of 3000 μm or less, more preferably 2500 μm or less. The thickness of each layer can be adjusted appropriately by changing the type of applicator used during molding or by changing the applicator gap. It can also be adjusted by changing the number of green sheets to be stacked. In this case, for example, green sheets with a thickness of 10 μm to 100 μm can be obtained and stacked to achieve the thickness within the aforementioned range.

[0074] Next, the layers are stacked and thermocompression bonded, thereby obtaining a first laminate. The oxide layer, the first layer, and the nickel oxide layer are stacked in the order corresponding to the layer order of the intended anode support cell. For example, when producing an anode support cell in which the fuel electrode functions as a support layer, the laminate may include an oxide layer, a first layer located on one side of the oxide layer, and a nickel oxide layer located on the side of the first layer opposite to the surface facing the oxide layer. The oxide layer, the first layer, and the nickel oxide layer may be in partial contact with each other in opposing regions, or may be in contact with each other over the entire opposing region. From the viewpoint of effectively producing a solid electrolyte having an apatite structure and being c-axis oriented, it is preferable that the oxide layer, the first layer, and the nickel oxide layer be in contact with each other over the entire opposing region.

[0075] The heating temperature in thermocompression bonding is preferably 50° C. or higher, more preferably 55° C. or higher, and even more preferably 60° C. or higher, from the viewpoint of softening the sheet by heat and increasing adhesion. From the same viewpoint, the heating temperature is preferably 100° C. or lower, more preferably 95° C. or lower, and even more preferably 90° C. or lower. The pressure during thermocompression bonding is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, and even more preferably 0.3 MPa or more, from the viewpoint of improving adhesion between the laminated sheets, and from the same viewpoint, the pressure is preferably 10.0 MPa or less, more preferably 5.0 MPa or less, and even more preferably 3.0 MPa or less.

[0076] Once the first laminate is obtained, it can be cut into a desired shape as needed. The first laminate is then heated to obtain a sintered body. This heating causes elements to diffuse between the oxide layer and the first layer, and a solid electrolyte with an apatite structure and c-axis orientation is produced from the oxide in the oxide layer. Specifically, SiO2 is liberated from La2SiO7 in the oxide layer, and Si derived from the liberated SiO2 diffuses from the oxide layer to the first layer. At the same time, La diffuses from the first layer to the oxide layer. In this way, a solid electrolyte consisting of a composite oxide of lanthanum and silicon is produced. Note that the amount of La diffusion from the oxide layer to the first layer due to this heating is considered negligible.

[0077] The heating temperature of the first laminate may be such that elements diffuse between the oxide layer and the first layer, and specifically, is preferably 1000°C or higher, more preferably 1300°C or higher, and even more preferably 1500°C or higher. A heating temperature of at least the above value allows Si to diffuse effectively from the oxide layer to the first layer, thereby facilitating stabilization of the apatite structure. For this reason, the higher the heating temperature, the better, but the desired effect can be fully achieved even at a heating temperature of 1700°C or lower. The heating time for the first laminate may be long enough to allow diffusion of elements between the oxide layer and the first layer, and is preferably 0.5 hours or longer, more preferably 1 hour or longer, and even more preferably 2 hours or longer. For the same reasons, the heating time is preferably 10 hours or shorter, more preferably 8 hours or shorter, and even more preferably 6 hours or shorter. Heating can be carried out, for example, by an electric furnace, a tubular furnace, etc. The atmosphere may be an oxygen-containing atmosphere such as air, or an inert gas atmosphere such as nitrogen gas or argon gas.

[0078] By the above heating, the oxide layer, the first layer, and the nickel oxide layer are respectively formed into a solid electrolyte layer, a first intermediate layer, and a fuel electrode that constitute the anode support cell.

[0079] Next, a raw material composition to be used in manufacturing the second intermediate layer is prepared. This raw material composition contains the common rare earth elements described above, as well as cerium and oxygen. This raw material composition may or may not be doped with an Ln element (Ln represents a rare earth element other than Ce). When the raw material composition is doped with an Ln element, the Ln element is preferably at least one element selected from the group consisting of La, Nd, and Sm, as described above. As such a raw material composition, cerium oxide doped or undoped with an Ln element (Ln represents a rare earth element other than Ce) can be prepared. Specifically, cerium oxide having the composition formula La 0.5 Ce 0.5 O 1.75 and Sm 0.2 Ce 0.8 O 1.9 can be prepared.

[0080] Once the raw material composition is prepared, a layer made of a material for the second intermediate layer is placed on the side of the layer containing the solid electrolyte (i.e., the solid electrolyte layer) of the sintered body of the first laminate opposite the surface facing the sintered layer of the first layer, thereby obtaining a second laminate. The second laminate can be obtained, for example, as a coating film by applying a slurry containing the raw material composition. The slurry can be obtained, for example, by adding the raw material composition to a binder prepared by dissolving ethyl cellulose in α-terpineol and adjusting the concentration. When forming the coating film, the slurry and the solid electrolyte layer may be in partial contact with each other in the opposing regions of the layers, or may be in contact with each other over the entire opposing regions of the layers. From the viewpoint of further improving the oxide ion conductivity of the anode-supported cell as a whole and enhancing the power generation characteristics of the anode-supported cell, it is preferable that the slurry and the solid electrolyte layer be in contact with each other over the entire opposing regions of the layers. The coating film is preferably formed so that the thickness of the second layer is 0.1 μm or more and 50 μm or less, from the viewpoint of successfully obtaining a desired anode-supported cell.

[0081] The second laminate is then heated to obtain a sintered body, which causes elements to diffuse between the solid electrolyte layer and the second layer, allowing the common rare earth element to be contained throughout the entire anode support cell. Specifically, when the raw material composition of the second intermediate layer contains only lanthanum as the common rare earth element, Si derived from the composite oxide in the solid electrolyte layer diffuses from the solid electrolyte layer to the second layer. At the same time, La diffuses from the second layer to the solid electrolyte layer. This results in a well-balanced content of the common rare earth element in each layer constituting the anode support cell. As a result, the oxide ion conductivity of the anode support cell as a whole is further improved, and the power generation characteristics of the anode support cell are enhanced. In this case, the diffusion of La from the solid electrolyte layer to the second layer due to the heating is considered to be negligible. Furthermore, when the raw material composition for the second intermediate layer contains only samarium as the common rare earth element, La derived from the composite oxide in the solid electrolyte layer diffuses from the solid electrolyte layer to the second layer. At the same time, Sm diffuses from the second layer to the solid electrolyte layer. This allows the common rare earth element to be contained throughout the anode support cell. As a result, the oxide ion conductivity of the entire anode support cell is further improved, and the power generation characteristics of the anode support cell are enhanced.

[0082] The heating temperature of the second laminate may be such that the elements diffuse between the solid electrolyte layer and the second layer, and specifically, is preferably 1000°C or higher, more preferably 1150°C or higher, and even more preferably 1300°C or higher. A heating temperature of at least this value allows Si or La to effectively diffuse between the solid electrolyte layer and the second layer, thereby allowing the common rare earth element to be contained throughout the anode support cell. For this reason, the higher the heating temperature, the better, but the desired effect can be sufficiently achieved even at a temperature of 1700°C or lower. The heating time for the second laminate may be sufficient to diffuse elements between the solid electrolyte layer and the second layer, and is preferably 0.1 hours or more, more preferably 0.3 hours or more, and even more preferably 0.5 hours or more. For the same reasons, the heating time is preferably 10 hours or less, more preferably 6 hours or less, and even more preferably 2 hours or less. Heating can be carried out, for example, by an electric furnace, a tubular furnace, etc. The atmosphere may be an oxygen-containing atmosphere such as air, or an inert gas atmosphere such as nitrogen gas or argon gas.

[0083] By the above heating, a second intermediate layer that constitutes the anode support cell is produced from the second layer.

[0084] Next, a raw material composition to be used for manufacturing the air electrode is prepared. This raw material composition contains lanthanum. For example, a raw material composition having the composition formula La 0.6 Sr 0.4 Co 0.2 Fe 0.8 A compound represented by O3 can be prepared. Once the raw material composition is prepared, a layer made of a material that will become the raw material for the air electrode is placed on the surface of the sintered layer of the second layer opposite the surface facing the solid electrolyte layer in the sintered body of the second laminate, thereby obtaining a third laminate. Such a layer can be obtained, for example, as a coating film by applying a slurry containing the raw material composition. The slurry can be obtained, for example, by adding the raw material composition to a binder prepared by dissolving ethyl cellulose in α-terpineol and adjusting the concentration. When forming the coating film, the slurry and the sintered layer of the second layer may be in partial contact with each other in the opposing regions, or may be in contact with each other over the entire opposing regions. From the perspective of further improving the oxide ion conductivity of the anode-supported cell as a whole and enhancing the power generation characteristics of the anode-supported cell, it is preferable that the slurry and the sintered layer of the second layer be in contact with each other over the entire opposing regions. The coating film is preferably formed so that the thickness of the air electrode is 1.0 μm or more and 30.0 μm or less, from the viewpoint of successfully obtaining a desired anode support cell.

[0085] Next, the third stack is heated to produce an air electrode. The heating temperature of the third stack is preferably lower than that of the first stack and the second stack. This makes it possible to suppress element diffusion between the solid electrolyte layer and the first and / or second layer in the sintered body during firing of the coating film, thereby enabling the production of a stable anode-supported cell. For this reason, the heating temperature of the third stack is preferably 1600°C or lower, more preferably 1500°C or lower, and even more preferably 1400°C or lower, provided that it is lower than that of the first stack and the second stack. For the same reason, it is preferably 600°C or higher, more preferably 700°C or higher, and even more preferably 800°C or higher. The heating temperature of the third stack may be sufficient to form an air electrode, and specifically, is preferably 0.1 hours or more, more preferably 0.3 hours or more, and even more preferably 0.5 hours or more. For the same reasons, it is preferably 10 hours or less, more preferably 9 hours or less, more preferably 8 hours or less, even more preferably 5 hours or less, and particularly preferably 2 hours or less. The heating time of the third stack and the heating time of the first stack and / or second stack may be the same or different.

[0086] Thereafter, if necessary, the anode support cell may be reduced to reduce metal oxides such as nickel oxide in the fuel electrode and the support layer described below in the anode support cell, thereby reducing, for example, nickel oxide to metallic nickel. The reduction can be carried out, for example, by hydrogen reduction under conditions commonly used in this technical field.

[0087] In this way, an anode-supported cell (i) is obtained in which the fuel electrode functions as a support layer.

[0088] Next, (ii) a method for manufacturing an anode-supported cell having a support layer separate from the fuel electrode will be described. In the following explanation, the method that differs from the method for manufacturing an anode-supported cell (i) will be mainly described. In this production method, a raw material composition used to produce the support layer is prepared in addition to raw material compositions for the solid electrolyte, the first layer, and the fuel electrode. The raw material composition used to produce the support layer contains lanthanum. Examples of such raw material compositions include nickel (II) oxide and La 9.33 SiO 26 A compound represented by the formula: Once the raw material composition is prepared, a slurry of the raw material composition is prepared. The slurry can be prepared using the same method as in the above-mentioned (i) production of the anode support cell. If necessary, a pore-forming agent can be used when preparing the slurry. The pore-forming agent thermally decomposes or sublimes at a predetermined temperature, so the support layer obtained by heating the green sheet containing the pore-forming agent has many pores. This facilitates gas diffusion. For example, cross-linked polymethyl methacrylate particles can be used as the pore-forming agent. Once the slurry is prepared, it is formed into a sheet to obtain a green sheet. This allows a preliminary support layer to be obtained from the support layer slurry. For forming, the same method as in the production of the anode support cell described above in (i) can be used. The preliminary support layer is preferably formed to have a predetermined thickness, from the viewpoint of successfully obtaining a desired anode support cell by heating the laminate described below. Specifically, the preliminary support layer preferably has a thickness of 200 μm or more, more preferably 300 μm or more. From the same viewpoint, the preliminary support layer preferably has a thickness of 3000 μm or less, more preferably 2500 μm or less. When adjusting the thickness by changing the number of green sheets to be laminated, for example, green sheets having a thickness of 10 μm or more and 300 μm or less may be obtained and laminated to obtain a thickness within the aforementioned range.

[0089] Next, the prepared layers are stacked and thermocompression bonded. This results in a first stack. In this embodiment (ii), the first stack is a stack of an oxide layer, a first layer, a nickel oxide layer, and a preliminary support layer. It should be noted that the configuration is different from the first stack described in the above embodiment (i). The oxide layer, the first layer, the nickel oxide layer, and the preliminary support layer are stacked in a manner corresponding to the order of the layers of the intended anode support cell. For example, when producing an anode support cell having a support layer separate from the fuel electrode, the stack may include an oxide layer, a first layer located on one side of the oxide layer, a nickel oxide layer located on the side of the first layer opposite the side facing the oxide layer, and a preliminary support layer located on the side of the nickel oxide layer opposite the side facing the first layer. The oxide layer, the first layer, the nickel oxide layer, and the preliminary support layer may be in partial contact with each other in opposing regions, or may be in contact with each other over the entire opposing region. From the viewpoint of effectively producing a solid electrolyte having an apatite structure and being c-axis oriented, it is preferable that the oxide layer, the first layer, the nickel oxide layer, and the preliminary support layer be in contact with each other over the entire opposing region.

[0090] Once the first laminate is obtained, it can be cut into a desired shape as needed. The first laminate is then heated to obtain a sintered body of the first laminate. This heating process produces the solid electrolyte layer, first intermediate layer, anode, and support layer that constitute the anode support cell from the oxide layer, first layer, nickel oxide layer, and preliminary support layer, respectively. Once the sintered body of the first laminate is obtained, the second intermediate layer can be formed by the same method as in (i) above, and then the air electrode can be formed by the same method as in (i) above. In this way, an anode-supported cell (ii) having a support layer separate from the fuel electrode is obtained.

[0091] The anode-supported cells obtained in (i) and (ii) above can be used in, for example, SOFCs, solid oxide water electrolysis cells (SOECs), oxygen permeation elements, gas sensors, and the like. The anode support cell can be operated, for example, by the following method. Specifically, hydrogen, methane, propane, biogas, or the like is first supplied to the fuel electrode, and air is supplied to the air electrode. Under this condition, the anode support cell is heated to, for example, 600°C to 1000°C, and the anode support cell is operated.

[0092] Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to these embodiments. For example, in the above embodiment, the second laminate was obtained by applying a slurry for the second layer. Alternatively, the second laminate may be obtained by preparing green sheets for the second layer and laminating them. Also, in the above embodiment, the third laminate was obtained by applying a slurry for the air electrode. Alternatively, the third laminate may be obtained by preparing green sheets for the air electrode and laminating them.

[0093] In the above embodiment, the first laminate including the oxide layer, the first layer, and the nickel oxide layer, or the first laminate including the oxide layer, the first layer, the nickel oxide layer, and the preliminary support layer, is heated at once. However, the oxide layer, the first layer, the nickel oxide layer, and / or the preliminary support layer may be heated sequentially.

[0094] In relation to the above embodiment, the following method for manufacturing an anode-supported cell is further disclosed. [1] A step of heating a first laminate including a layer containing an oxide represented by the composition formula La2Si2O7, a first layer containing cerium oxide doped with lanthanum and located on one side of the layer containing the oxide, and a layer containing nickel oxide and located on the side of the first layer opposite to the surface facing the layer containing the oxide, at 1000°C or higher to produce a solid electrolyte having an apatite structure and oriented along its c-axis from the oxide; a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped with an Ln element (Ln represents a rare earth element other than cerium) or undoped on the surface of the layer containing the solid electrolyte opposite to the surface facing the layer containing cerium oxide; and heating the second laminate at 1000°C or higher; A method for producing an anode supported cell using the nickel oxide-containing layer having a thickness of 300 μm or more and 3000 μm or less. [2] A step of heating a first laminate including a layer containing an oxide represented by the composition formula La2Si2O7, a first layer containing cerium oxide doped with lanthanum and located on one surface of the layer containing the oxide, a layer containing nickel oxide and located on the side of the first layer opposite to the surface facing the layer containing the oxide, and a preliminary support layer located on the side of the layer containing nickel oxide opposite to the surface facing the first layer, at 1000°C or higher to produce a solid electrolyte having an apatite structure and oriented along its c-axis from the oxide; a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped with an Ln element (Ln represents a rare earth element other than cerium) or undoped on the surface of the layer containing the solid electrolyte opposite to the surface facing the layer containing cerium oxide; and heating the second stack at 1000°C or higher.

[0095] [3] The method according to [1] or [2], wherein the Ln element is at least one selected from the group consisting of La, Nd, and Sm. [4] The method according to any one of [1] to [3], wherein the solid electrolyte is formed from a composite oxide of lanthanum and silicon. [5] A 9.33+x [T 6.00 ]O 26.00+z(wherein A is one or more elements selected from the group consisting of La, Ce, Nd, and Sm; and T is Si), wherein x in the formula is a number equal to or greater than −1.33 and equal to or less than 3.00, z in the formula is a number equal to or greater than −5.00 and equal to or less than 5.20, and the ratio of the number of moles of A to the number of moles of T (A / T) is 1.33 or greater and 3.61 or less. [6] obtaining a third laminate by disposing a layer made of a material that will be a raw material for an air electrode on the surface of the sintered layer of the second layer opposite to the surface facing the layer containing the solid electrolyte in the sintered body of the second laminate obtained by heating; The manufacturing method described in [1], further comprising a step of heating the third laminate. [7] a step of obtaining a third laminate by disposing a layer made of a material that will be a raw material for an air electrode on the surface of the sintered body of the second layer opposite to the surface facing the layer containing the solid electrolyte in the sintered body of the second layer obtained by heating; The manufacturing method described in [2], further comprising a step of heating the third laminate. [Example]

[0096] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, "%" means "% by mass."

[0097] Example 1 (1) Manufacturing and heating of the first laminate To prepare the raw material composition for the solid electrolyte, 9.005 g of La2SiO7 powder and 4.933 g of ethanol were weighed out. These raw material compositions were mixed to form a slurry. Then, 0.831 g of PVB resin powder (a binder) and 0.955 g of dibutyl phthalate (a plasticizer) were further mixed into this slurry to prepare the slurry for the solid electrolyte. The raw material composition used to manufacture the first intermediate layer is La 0.5 Ce 0.5 O 1.7510.104 g of the powder and 9.242 g of ethanol were weighed out. These raw material compositions were mixed to form a slurry. 1.136 g of PVB resin powder as a binder and 1.164 g of dibutyl phthalate as a plasticizer were then further mixed into this slurry to prepare a slurry for use in manufacturing the first intermediate layer. The raw material composition used to manufacture the anode was 7.291 g of nickel oxide powder, 1.291 g of La 0.5 Ce 0.5 O 1.75 9.008 g of the powder and 15.75 g of ethanol were weighed out. These raw material compositions were mixed to form a slurry. Then, 1.445 g of PVB resin powder as a binder and 1.514 g of dibutyl phthalate as a plasticizer were further mixed into this slurry to prepare a slurry for use in manufacturing the anode. The raw material composition used to manufacture the support layer was 20.724 g of NiO powder, 20.724 g of La 9.33 SiO 26 19.657 g of the powder, 30.340 g of ethanol, and 10.115 g of spherical microparticles (average particle size 30 μm) of cross-linked polymethyl methacrylate (a pore-forming agent) were weighed. These raw material compositions were mixed to form a slurry. Then, 4.953 g of PVB resin powder (a binder) and 6.219 g of dibutyl phthalate (a plasticizer) were further mixed with this slurry to prepare the slurry used for manufacturing the support layer.

[0098] Green sheets were prepared from each slurry using an automatic film applicator. The thickness gap of the automatic film applicator was 40 μm. The resulting oxide layer thickness was 20 μm. The first layer thickness was 19 μm. The nickel oxide layer thickness was 33 μm. The preliminary support layer thickness was 220 μm. Next, an oxide layer, a first layer located on one side of the oxide layer, a nickel oxide layer located on the side of the first layer opposite the side facing the oxide layer, and a preliminary support layer located on the side of the nickel oxide layer opposite the side facing the first layer were laminated, and then thermocompression-bonded from one direction to obtain a first laminate. The oxide layer, first layer, and nickel oxide layer were each formed of one green sheet, and the preliminary support layer was formed of six green sheets. Thermocompression bonding was performed at 60°C and 0.3 MPa. The obtained first laminate was heated in an air atmosphere at 1600°C for 5 hours, thereby obtaining a sintered body of the first laminate, and producing a solid electrolyte layer, a first intermediate layer, an anode, and a support layer from the oxide layer, the first layer, the nickel oxide layer, and the preliminary support layer, respectively.

[0099] (2) Manufacturing and heating of the second laminate The raw material composition used to manufacture the second intermediate layer is Sm 0.2 Ce 0.8 O 1.9 4.5 g of powder was weighed out. This powder was mixed with 3.0 g of a solution in which 5 wt % of ethyl cellulose was dissolved in α-terpineol to prepare a slurry. This slurry was applied to the sintered body of the first laminate to a thickness of 5 μm on the side of the solid electrolyte layer opposite to the surface facing the sintered layer of the first layer, to obtain a second laminate. This second laminate was heated at 1400°C for 1 hour in an air atmosphere. This produced a second intermediate layer.

[0100] (3) Manufacturing and heating of the third laminate The raw material composition used to manufacture the air electrode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ3.0 g of powder was weighed out. This powder was mixed with 4.5 g of a solution in which 5 wt % of ethyl cellulose was dissolved in α-terpineol to prepare a slurry. This slurry was applied to the sintered body of the second laminate to a thickness of 10 μm on the side of the second sintered layer opposite the side facing the solid electrolyte layer, to obtain a third laminate. This third laminate was heated at 900°C for 1 hour in an air atmosphere. This produced an air electrode. In this way, the desired anode-supported cell was obtained.

[0101] Example 2 In Example 1, the thickness of the automatic film applicator was changed to a 60 μm gap so that the thickness of the electrolyte increased. 0.2 Ce 0.8 O 1.9 The amount of powder was 1.5 g, and a slurry prepared using 2.2 g of an α-terpineol solution of ethyl cellulose was used. Except for this, an anode supported cell was obtained in the same manner as in Example 1.

[0102] Comparative Example 1 In Example 1, the La used in producing the first intermediate layer 0.5 Ce 0.5 O 1.75 The powder was mixed with an equal amount of Sm 0.2 Ce 0.8 O 1.9 The anode support cell was obtained in the same manner as in Example 1 except for the above, ...

[0103] Comparative Example 2 In Example 1, the La used in producing the first intermediate layer 0.5 Ce 0.5 O 1.75 The powder was mixed with an equal amount of Sm 0.2 Ce 0.8 O 1.9 Anode support cells were obtained in the same manner as in Example 1 except for this.

[0104] 〔evaluation〕 For the anode supported cells obtained in the examples and comparative examples, the composition of the oxide contained in each layer was determined, and the lanthanum contents n1 to n6 in each layer and the thickness of each layer were measured by the following methods. In addition, in the examples and comparative examples, after obtaining the sintered body of the first laminate, XRD measurement was performed on the solid electrolyte layer. It was confirmed that the solid electrolyte layer of the anode support cell of the examples had an apatite structure, and the degree of c-axis orientation f was measured for the solid electrolyte layer of the anode support cell of the examples and comparative examples. The maximum power density of the anode supported cells obtained in the examples and comparative examples was measured by the following method. The results are shown in Table 1.

[0105] [Lanthanum content] The contents of Sr, Co, Fe, and La in the air electrode were measured by point analysis using SEM (scanning electron microscope)-EDS for a cross section of the anode support cell approximately parallel to the thickness direction. Table 1 shows the measured contents of each element as a percentage (mol%) of the total amount of Sr, Co, Fe, and La. Similarly, the contents of Sm, Ce and La elements contained in the second intermediate layer, the first intermediate layer and the fuel electrode were measured, and these are shown in Table 1 as the ratio (mol%) to the total amount of Sm, Ce and La elements. Furthermore, the contents of Si, Sm, Ce, and La elements contained in each of the solid electrolyte layer and the support layer were measured, and the results are shown in Table 1 as the ratio (mol%) to the total amount of Si, Sm, Ce, and La elements.

[0106] [Thickness of each layer] The thickness of each layer was measured by SEM-EDS.

[0107] [XRD measurement] The XRD device used was a fully automatic multipurpose X-ray diffractometer SmartLab manufactured by Rigaku Corporation, and measurements were performed under the following conditions: The XRD chart of the example is shown in FIG. Tube voltage: 40kV Tube current: 30mA X-ray source:CuKα Incident optics: Confocal mirror (CMF) Incident slit configuration: Collimator size 1.4mm x 1.4mm Receiving side slit configuration: parallel slit analyzer 0.114 deg, receiving slit 20 mm Detector: Scintillation counter Measurement range: 2θ=20~60deg Step width: 0.01deg Scan speed: 1deg / min

[0108] [c-axis orientation degree f] The data obtained by the XRD measurement described above was analyzed using a PDXL2 manufactured by Rigaku Corporation. A straight line connecting the endpoints was selected as the background, and a split pseudo-Voigt function was selected as the peak shape. Profile fitting was then performed to obtain the peak intensities (integrated intensities) of the (002) and (004) planes. The degree of c-axis orientation, f, was calculated based on the aforementioned equation (1). As mentioned above, the peaks attributable to the (002) and (004) planes are peaks specific to the c-axis orientation and are independent peaks that do not overlap with the diffraction angle values ​​attributable to other planes. If there is overlap with a peak from another phase, which is expected when an anode support cell has a multilayer structure, the peaks can be resolved in the same way as in general XRD data analysis, so that the peak intensities of only the (002) and (004) planes can be obtained.

[0109] [Maximum power density] At a temperature of 700°C, 100 ccm of hydrogen was flowed through the fuel electrode as fuel gas, and 80 ccm of nitrogen and 20 ccm of oxygen were flowed through the air electrode. The voltage was swept at 10 mV / min from OCV to OCV-0.9 V, and the voltage and current values ​​were measured. The maximum value obtained by multiplying the measured voltage and current density values ​​was taken as the maximum power density.

[0110] [Table 1]

[0111] As is clear from the results shown in Fig. 4, peaks were detected on the (002) and (004) planes that are characteristic of an apatite structure in the anode-supported cells obtained in the examples. Therefore, it was confirmed that the solid electrolyte layers in the anode-supported cells of Examples 1 and 2 had an apatite structure. Furthermore, as is clear from the results shown in Table 1, the anode supported cells obtained in the examples have a higher maximum power density than the anode supported cells obtained in the comparative examples. [Explanation of symbols]

[0112] 10 Anode Support Cell 11 Solid electrolyte layer 12 Air electrode 13 Fuel electrode 14 First middle layer 15 Second middle layer 16 Middle class 17 Support layer

Claims

1. Composition formula La ２ Si ２ O ７ a first layer including a layer containing an oxide represented by the formula (I), a first layer including cerium oxide doped with lanthanum and located on one surface of the layer containing the oxide, and a layer including nickel oxide and located on the opposite surface of the first layer to the surface facing the layer containing the oxide, by heating the first layer at 1000°C or higher to produce a solid electrolyte having an apatite structure and c-axis orientation from the oxide; a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped with an Ln element (Ln represents a rare earth element other than cerium) or undoped on the surface of the layer containing the solid electrolyte opposite to the surface facing the layer containing cerium oxide; and heating the second laminate at 1000°C or higher; A method for producing an anode supported cell using the nickel oxide-containing layer having a thickness of 300 μm or more and 3000 μm or less.

2. Composition formula La ２ Si ２ O ７ a first layer including a layer containing an oxide represented by the formula (I), a first layer including cerium oxide doped with lanthanum and located on one surface of the layer containing oxide, a layer including nickel oxide and located on the opposite surface of the first layer to the surface facing the layer containing oxide, and a preliminary support layer including a layer containing nickel oxide and located on the opposite surface of the layer containing nickel oxide to the surface facing the first layer, thereby heating the first laminate at 1000°C or higher to produce a solid electrolyte having an apatite structure and c-axis orientation from the oxide; a step of obtaining a second laminate by disposing a second layer containing cerium oxide doped with an Ln element (Ln represents a rare earth element other than cerium) or undoped on the surface of the layer containing the solid electrolyte opposite to the surface facing the layer containing cerium oxide; and heating the second stack at 1000°C or higher.

3. 3. The method according to claim 1, wherein the Ln element is at least one element selected from the group consisting of La, Nd, and Sm.

4. 3. The method according to claim 1, wherein the solid electrolyte is formed from a composite oxide of lanthanum and silicon.

5. A ９．３３＋ｘ [T ６．００ ]O ２６．００＋ｚ (wherein A is one or more elements selected from the group consisting of La, Ce, Nd, and Sm; and T is Si), wherein x in the formula is a number equal to or greater than −1.33 and equal to or less than 3.00, z in the formula is a number equal to or greater than −5.00 and equal to or less than 5.20, and the ratio of the number of moles of A to the number of moles of T (A / T) is 1.33 or greater and 3.61 or less.

6. a step of arranging a layer made of a material that will be a raw material for an air electrode on the surface of the sintered layer of the second layer opposite to the surface facing the layer containing the solid electrolyte in the sintered body of the second laminate obtained by heating, to obtain a third laminate; The method of claim 1 further comprising the step of: heating the third laminate.

7. a step of obtaining a third laminate by disposing a layer made of a material that will be a raw material for the air electrode on the surface of the sintered body of the second layer opposite to the surface facing the layer containing the solid electrolyte in the sintered body of the second layer obtained by heating; The method of claim 2 further comprising the step of: heating the third laminate.

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