Method of manufacturing laminate of electrolyte and fuel electrode for proton-conductive solid oxide cell, electrolyte for proton-conductive solid oxide cell, and proton-conductive solid oxide cell including the same

Abstract

To provide a method for manufacturing an electrolyte having high proton conductivity by increasing the particle size of crystal particles of the electrolyte for a proton conductive solid oxide cell and densifying the electrolyte by reducing or eliminating pinholes.SOLUTION: Laminating a fuel electrode material layer containing an electron conducting oxide for a fuel electrode containing Ni, a perovskite-type proton conducting oxide (a) containing at least Ba, Sr, or Ca as an A-site element, and a Ba, Sr, or Ca compound, and an electrolyte material layer containing a perovskite-type proton conducting oxide (b) containing at least Ba, Sr, or Ca as an A-site element; A method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell, the method comprising: a raw material layer laminate producing step of producing a laminate of an electrolyte material layer and a fuel electrode material layer; and a firing step of firing the laminate of the electrolyte material layer and the fuel electrode material layer at 1150 to 1700 °C to obtain a laminate of an electrolyte and a fuel electrode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell, an electrolyte for a proton-conducting solid oxide cell, and a proton-conducting solid oxide cell having the electrolyte. [Background technology]

[0002] Solid oxide cells for electrochemical reactions are devices that enable highly efficient energy conversion, and research and development toward their practical application is underway by ceramic manufacturers, the energy industry, the automotive industry, etc. For example, they are used in devices such as fuel cell systems, electrolysis systems, and hydrogen compressors.

[0003] Typical examples of devices using solid oxide cells include solid oxide fuel cells and solid oxide electrolysis cells. A solid oxide cell is composed of a dense electrolyte, primarily made of oxide, sandwiched between two porous electrodes: an air electrode and a fuel electrode. Depending on the constituent materials, a wide operating temperature range can be selected for this solid oxide cell, and it can be used in the range of 400 to 1000°C.

[0004] The electrode material is an electron-conductive oxide or metal with catalytic activity (hereinafter referred to as "electron-conductive material"). Although electron-conductive materials may be used alone, they may also be mixed with an ion-conductive material that conducts the same ions as the electrolyte or the same ions as the electrolyte ("ions" refers to all ions that act as conductive carriers, including oxide ions and protons), in order to expand the reaction field within the electrode. In general, the reaction resistance of the electrode is reduced by mixing an electron-conductive material with an ion-conductive material. The reaction resistance depends on the size of the reaction field (or the number of reaction active sites) per unit area of ​​the electrode and the activity per reaction field.

[0005] In solid oxide fuel cells, the charge carrier ions are mainly oxide ions and protons. Among solid oxide cells, those in which the charge carrier ions are mainly protons are called proton-conducting ceramic cells. In proton-conducting ceramic cells, the material that conducts protons is called a proton-conducting electrolyte. Typical examples of proton-conducting electrolytes include perovskite-type oxide materials.

[0006] Compared to oxide-ion conducting ceramic cells, proton conducting solid oxide cells have the advantage that they can increase fuel utilization rate because water vapor is not generated at the anode when used in fuel cells, and when used as electrolysis cells, they can increase the hydrogen concentration by discharging hydrogen to the anode side, resulting in higher energy conversion efficiency.Furthermore, because the activation energy of proton conduction is low, they have the advantage that they can be used at lower operating temperatures than oxide-ion conducting ceramic fuel cells.

[0007] Research and development of proton-conducting solid oxide cells to date has focused on oxides such as (LaSr)MnO3, (LaSr)FeO3, (LaSr)CoO3, and (LaSr)(CoFe)O3 as the cathode material, oxides such as Ba(ZrYb)O3 and Ba(ZrCeYYb)O3 as the electrolyte material, and cermets such as NiO-Ba(ZrYb)O3 as the fuel electrode material.

[0008] A proton-conducting solid oxide cell needs to have a high output (maximum output density). Therefore, Non-Patent Document 1 describes that when firing an anode and an electrolyte made of a BaZrCeYYb composite oxide, a BaZrCeYYb composite oxide pellet having the same composition as the electrolyte is placed to prepare the anode and electrolyte, thereby making the barium content near the electrolyte surface approximately the same as the barium content inside the electrolyte, thereby improving cell performance. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Mingi Choi, Jaedeok Paik, Donguk Kim, Deokyoon Woo, Jaeyeob Lee,Seo Ju Kim, Jongseo Lee and Wonyoung Lee, Energy Environ. Sci., 2021, 14, 6476-6483 Summary of the Invention [Problem to be solved by the invention]

[0010] One method for improving the performance of a proton-conducting solid oxide cell is to improve the proton conductivity of the electrolyte.

[0011] However, conventional electrolytes for proton-conducting solid oxide cells have a problem of low proton conductivity due to the small particle size of the crystal grains that make up the electrolyte and the large number of crystal grain boundaries.

[0012] Furthermore, if the crystal grains are small, pinholes are formed in the electrolyte, which can cause gas leaks.

[0013] Therefore, an object of the present invention is to provide a method for producing a densified electrolyte with high proton conductivity and no gas leakage by increasing the grain size of the crystal grains in the electrolyte for a proton-conducting solid oxide cell, reducing the grain boundaries, and reducing or eliminating pinholes. [Means for solving the problem]

[0014] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that, when firing an electrolyte to produce it, the particle size of the crystal particles forming the electrolyte becomes large and the electrolyte becomes dense by laminating an anode material layer containing an Ni-containing electron-conductive oxide for an anode, a perovskite-type proton-conducting oxide (a) containing one of Ba, Sr, and Ca as an A-site element, and a compound containing the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca, and an electrolyte material layer containing a perovskite-type proton-conducting oxide containing the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca, to produce a laminate of the electrolyte material layer and the anode material layer, and firing the produced laminate, which led to the development of the present invention.

[0015] That is, the present invention (1) provides a method for producing a laminate of an electrolyte and anode for a proton-conducting solid oxide cell, the method comprising: a raw material layer laminate fabricating step of stacking an anode material layer containing an electronically conductive oxide for anode containing Ni; a perovskite-type proton-conducting oxide (a) containing, as an A-site element, one of Ba, Sr, and Ca; and a compound containing the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca; and an electrolyte material layer containing a perovskite-type proton-conducting oxide (b) containing, as an A-site element, the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca; and a firing step of firing the laminate of the electrolyte material layer and the anode material layer at 1150 to 1700°C to obtain a laminate of the electrolyte and anode.

[0016] The present invention (2) also provides a method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell according to (1), characterized in that the perovskite-type proton-conducting oxide (a) is a perovskite-type proton-conducting oxide containing Zr as a B-site element, and the perovskite-type proton-conducting oxide (b) is a perovskite-type proton-conducting oxide containing Zr as a B-site element.

[0017] In addition, the present invention (3) is characterized in that the anode material layer is formed on a setter, the setter is a material through which the same element as the A-site element of the perovskite-type proton-conducting oxide (a), selected from Ba, Sr, and Ca, and Ni can diffuse or penetrate; The present invention provides a method for producing a laminate of an electrolyte and a fuel electrode for a proton-conductive solid oxide cell according to (1) or (2), characterized by the above.

[0018] The present invention (4) is an electrolyte formed of crystal particles of a perovskite-type proton-conducting oxide containing Ba as an A-site element and Zr as a B-site element, and in which the content of Ce in atomic terms relative to the total B-site elements is 10.0 mol % or less, In a scanning electron microscope (SEM) image, the average particle size of the crystal particles is 1.5 to 5.0 μm; the Ni content in the electrolyte is 0.80 at% or less; The present invention provides an electrolyte for a proton-conducting solid oxide cell, characterized by:

[0019] The present invention (5) also provides an electrolyte for a proton-conductive solid oxide cell according to (4), characterized in that the content of the sintering aid is 0.50 at % or less.

[0020] The present invention (6) also provides a proton-conducting solid oxide cell characterized by having the electrolyte for the proton-conducting solid oxide cell of (4).

[0021] In this specification, when a numerical range is indicated using "to", the numerical values ​​at both ends are included. In other words, "XX to △△" means "greater than or equal to XX and less than or equal to △△". [Effects of the Invention]

[0022] According to the present invention, a method for producing an electrolyte having high proton conductivity can be provided by increasing the particle size of crystal particles in an electrolyte for a proton-conducting solid oxide cell and reducing or eliminating pinholes to increase density. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic end view of one embodiment of a method for manufacturing a laminate of an electrolyte and an anode for a proton-conducting solid oxide cell of the present invention. FIG. [Figure 2] 1 shows scanning electron microscope photographs (SEM images) of the electrolyte of the laminate of the electrolyte and the fuel electrode obtained in Examples 2 to 9 and Comparative Examples 1 to 3. [Figure 3] 1 shows scanning electron microscope photographs (SEM images) of the electrolyte of the laminate of the electrolyte and the fuel electrode obtained in Example 9 and Comparative Example 3. [Figure 4] 1 shows particle size distribution curves for Examples 4, 7, and 9. [Figure 5] 1 is a graph showing the Ni concentration of the electrolyte in the laminate of the electrolyte and the fuel electrode obtained in Examples 1 to 6 and 10 to 16. [Figure 6] 1 shows the results of evaluation of the proton conductivity of the laminates of the electrolyte and the fuel electrode obtained in Examples 4 to 6 and Comparative Example 3. [Figure 7] 1 shows the results of performance evaluation of proton-conducting solid oxide cells using the laminates of electrolytes and fuel electrodes obtained in Examples 13 and 15. DETAILED DESCRIPTION OF THE INVENTION

[0024] The method for producing a laminate of an electrolyte and anode for a proton-conducting solid oxide cell of the present invention comprises the steps of: laminating an anode material layer containing an electron-conductive oxide for anode containing Ni; a perovskite-type proton-conducting oxide (a) containing one of Ba, Sr, and Ca as an A-site element; and a compound containing the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca; and an electrolyte material layer containing a perovskite-type proton-conducting oxide (b) containing the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca as an A-site element; and firing the laminate of the electrolyte material layer and the anode material layer at 1150 to 1700°C to obtain a laminate of the electrolyte and anode.

[0025] Among the methods for producing a laminate of an electrolyte and an anode for a proton-conducting solid oxide cell of the present invention, when the A-site element of the perovskite-type proton-conducting oxide (a) is Ba, the method is a first embodiment of the method for producing a laminate of an electrolyte and an anode for a proton-conducting solid oxide cell of the present invention (also referred to as method (1) for producing a laminate of an electrolyte and an anode of the present invention). When the A-site element of the perovskite-type proton-conducting oxide (a) is Sr, the method is a second embodiment of the method for producing a laminate of an electrolyte and an anode for a proton-conducting solid oxide cell of the present invention (also referred to as method (2) for producing a laminate of an electrolyte and an anode of the present invention). When the A-site element of the perovskite-type proton-conducting oxide (a) is Ca, the method is a third embodiment of the method for producing a laminate of an electrolyte and an anode for a proton-conducting solid oxide cell of the present invention (also referred to as method (3) for producing a laminate of an electrolyte and an anode of the present invention).

[0026] That is, the method (1) for producing a laminate of an electrolyte and an anode of the present invention includes a raw material layer laminate production step of laminating an anode material layer containing an Ni-containing electron conductive oxide for an anode, a perovskite-type proton conductive oxide (1a) containing at least Ba as an A-site element, and a Ba compound, and an electrolyte material layer containing a perovskite-type proton conductive oxide (1b) containing at least Ba as an A-site element, to produce a laminate of an electrolyte material layer and an anode material layer; a firing step of firing the laminate of the electrolyte material layer and the anode material layer at 1150 to 1700°C to obtain a laminate of the electrolyte and the anode; The present invention relates to a method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell, the laminate comprising:

[0027] The method (2) for producing a laminate of an electrolyte and an anode of the present invention includes a raw material layer laminate production step of laminating an anode material layer containing an Ni-containing electron conductive oxide for an anode, a perovskite-type proton conductive oxide (2a) containing at least Sr as an A-site element, and a Sr compound, and an electrolyte material layer containing a perovskite-type proton conductive oxide (2b) containing at least Sr as an A-site element, to produce a laminate of an electrolyte material layer and an anode material layer; a firing step of firing the laminate of the electrolyte material layer and the anode material layer at 1150 to 1700°C to obtain a laminate of the electrolyte and the anode; The present invention relates to a method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell, the laminate comprising:

[0028] The method (3) for producing a laminate of an electrolyte and an anode of the present invention includes a raw material layer laminate production step of laminating an anode material layer containing an Ni-containing electron conductive oxide for an anode, a perovskite-type proton conductive oxide (3a) containing at least Ca as an A-site element, and a Ca compound, and an electrolyte material layer containing a perovskite-type proton conductive oxide (3b) containing at least Ca as an A-site element, to produce a laminate of an electrolyte material layer and an anode material layer; a firing step of firing the laminate of the electrolyte material layer and the anode material layer at 1150 to 1700°C to obtain a laminate of the electrolyte and the anode; The present invention relates to a method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell, the laminate comprising:

[0029] FIG. 1 is a schematic end view of one embodiment of the method for manufacturing a laminate of an electrolyte and an anode for a proton-conducting solid oxide cell of the present invention. While FIG. 1 illustrates an example in which the A-site element of the perovskite-type proton-conducting oxide (a) is Ba, the present invention is not limited thereto. The A-site element of the perovskite-type proton-conducting oxide (a) may be Ba, Sr, or Ca. First, a dispersion slurry of anode raw materials containing a Ni-containing anode electron-conducting oxide, a perovskite-type proton-conducting oxide (1a) containing at least Ba as an A-site element, and a Ba compound is tape-cast and dried to obtain a green sheet for anode material layer 2. Next, a dispersion slurry of electrolyte raw materials containing a perovskite-type proton-conducting oxide (1b) containing at least Ba as an A-site element is tape-cast and dried to obtain a green sheet for electrolyte material layer 1. Next, one or more green sheets for the anode material layer 2 and one or more green sheets for the electrolyte material layer 1 are laminated to a predetermined thickness and heated and pressed to produce a laminate 4 of the electrolyte material layer 1 and the anode material layer 2. Next, the laminate 4 of the electrolyte material layer 1 and the anode material layer 2 is placed on a setter 3 and fired at 1150 to 1700°C, preferably 1300 to 1500°C, to obtain a laminate of the electrolyte and the anode.

[0030] The method for producing a laminate of an electrolyte and an anode of the present invention includes a raw material layer laminate preparation step and a firing step.

[0031] The raw material layer laminate fabrication step in the method for manufacturing a laminate of an electrolyte and an anode of the present invention is a step of laminating anode material layers and electrolyte material layers to fabricate a laminate of electrolyte material layers and anode material layers.

[0032] The anode material layer contains an anode electron conductive oxide containing Ni, a perovskite-type proton conductive oxide (a) that is an ABO3-type perovskite-type proton conductive oxide containing one of Ba, Sr, and Ca as an A-site element, and a compound containing the same A-site element from among Ba, Sr, and Ca as the A-site element of the perovskite-type proton conductive oxide (a) contained in the anode material layer. In the manufacturing method (1) of the electrolyte and anode laminate of the present invention, the perovskite-type proton conductive oxide (a) is a perovskite-type proton conductive oxide (1a) containing at least Ba as an A-site element, and the compound containing the same A-site element from among Ba, Sr, and Ca as the A-site element of the perovskite-type proton conductive oxide (a) is a Ba compound. In the method (2) for producing a laminate of an electrolyte and a fuel electrode of the present invention, the perovskite-type proton-conducting oxide (a) is a perovskite-type proton-conducting oxide (2a) containing at least Sr as an A-site element, and a compound containing the same element as the A-site element of the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca is a Sr compound. In the method (3) for producing a laminate of an electrolyte and a fuel electrode of the present invention, the perovskite-type proton-conducting oxide (a) is a perovskite-type proton-conducting oxide (3a) containing at least Ca as an A-site element, and a compound containing the same element as the A-site element of the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca is a Ca compound. That is, the anode material layer is a layered molded body comprising at least an anode electronically conductive oxide containing Ni, which is the raw material for the anode; a perovskite-type proton-conductive oxide (a) containing one of Ba, Sr, and Ca as an A-site element; and a compound containing the same element as the A-site element of the perovskite-type proton-conductive oxide (a) from among Ba, Sr, and Ca.

[0033] Examples of Ni-containing electronically conductive oxides for the anode in the anode material layer include NiO, NiFeOx, NiCoOx, NiFeCoOx, etc., with NiO being preferred. The Ni-containing electronically conductive oxides for the anode may be one type or a combination of two or more types.

[0034] The average particle size of the Ni-containing electron conductive oxide for the anode in the anode material layer is not particularly limited, but is preferably 0.01 to 10 μm, more preferably 0.01 to 4 μm.

[0035] The perovskite-type proton-conducting oxide (a) containing any one of Ba, Sr, and Ca as the A-site element for the anode material layer is an ABO3-type perovskite-type proton-conducting oxide, containing any one of Ba, Sr, and Ca as the A-site element. The perovskite-type proton-conducting oxide (a) also contains at least Zr or Ce, preferably at least Zr, as the B-site element. The perovskite-type proton-conducting oxide (a) is preferably a perovskite-type proton-conducting oxide represented by the following general formula (I): M x1 (Zr α1 A1 (1-α1) ) y1 O 3-z1 (I) (In formula (I), M is any one of Ba, Sr, and Ca, A1 is at least one trivalent or tetravalent element, x1 is 0.90 to 1.10, α1 is 0.10 to 1.00, y1 is 0.90 to 1.10, and z1 is 0.00 to 0.50.) Examples of the perovskite-type proton-conducting oxide include those represented by the following formula:

[0036] In general formula (I), M is any one of Ba, Sr, and Ca. In the method (1) for producing a laminate of an electrolyte and an anode of the present invention, M is Ba. In the method (2) for producing a laminate of an electrolyte and an anode of the present invention, M is Sr. In the method (3) for producing a laminate of an electrolyte and an anode of the present invention, M is Ca. In general formula (I), A1 is at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc, preferably at least one of Ce, Y, and Yb, and more preferably Yb. x1 is 0.90 to 1.10, preferably 0.96 to 1.05, and more preferably 0.98 to 1.01. α1 is 0.10 to 1.00, preferably 0.50 to 0.95, more preferably 0.70 to 0.90, and more preferably 0.75 to 0.85. y1 is 0.90 to 1.10, preferably 0.96 to 1.05, and more preferably 0.98 to 1.01. z1 is 0.00 to 0.40, preferably 0.00 to 0.30, and more preferably 0.00 to 0.15. When A1 is two or more elements, the value of 1-α1 is the total value of those two or more elements, and the value of y1 is the total value of Zr and those two or more elements.

[0037] The perovskite-type proton-conducting oxide represented by the general formula (I) may be one type or a combination of two or more types, as long as it satisfies the general formula (I).

[0038] The perovskite-type proton-conducting oxide (a) may be a perovskite-type proton-conducting oxide represented by the following general formula (II): M x2 (Ce α2 A2 (1-α2) ) y2 O 3-z2 (II) (In formula (II), M is any one of Ba, Sr, and Ca; A2 is at least one trivalent or tetravalent element; x2 is 0.90 to 1.10; α2 is 0.10 to 1.00; y2 is 0.90 to 1.10; and z2 is 0.00 to 0.50.) Examples of the perovskite-type proton-conducting oxide include those represented by the following formula:

[0039] In general formula (II), M is any one of Ba, Sr, and Ca. In the method (1) for producing a laminate of an electrolyte and an anode of the present invention, M is Ba. In the method (2) for producing a laminate of an electrolyte and an anode of the present invention, M is Sr. In the method (3) for producing a laminate of an electrolyte and an anode of the present invention, M is Ca. In general formula (II), A2 is at least one of Ti, Zr, Hf, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc, preferably at least one of Zr, Y, and Yb, and more preferably Y. x2 is 0.90 to 1.10, preferably 0.96 to 1.05, and more preferably 0.98 to 1.01. α2 is 0.10 to 1.00, preferably 0.50 to 0.95, more preferably 0.70 to 0.90, and more preferably 0.75 to 0.85. y2 is 0.90 to 1.10, preferably 0.96 to 1.05, and more preferably 0.98 to 1.01. z2 is 0.00 to 0.40, preferably 0.00 to 0.30, and more preferably 0.00 to 0.15. When A2 is two or more elements, the value of 1-α2 is the total value of those two or more elements, and the value of y2 is the total value of Ce and those two or more elements.

[0040] The perovskite-type proton-conducting oxide represented by the general formula (II) may be one type or a combination of two or more types, as long as it satisfies the general formula (II).

[0041] The average particle size of the perovskite-type proton-conductive oxide (a) for the fuel electrode material layer is not particularly limited, but is preferably 0.01 to 10 μm, more preferably 0.01 to 4 μm.

[0042] The compound containing the same element as the A-site element of the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca in the anode material layer is not particularly limited, as long as it is a compound containing the same element as the A-site element of the perovskite-type proton-conducting oxide (a) contained in the anode material layer among Ba, Sr, and Ca. The Ba compound for the anode material layer is not particularly limited, and examples thereof include Ba carbonate, hydrochloride, sulfate, nitrate, and acetate, and preferred are barium carbonate, barium oxide, barium hydroxide, barium chloride, barium sulfate, barium nitrate, and barium acetate. The Sr compound for the fuel electrode material layer is not particularly limited, and examples thereof include Sr carbonate, hydrochloride, sulfate, nitrate, acetate, etc., and preferred are strontium carbonate, strontium oxide, strontium hydroxide, strontium hydrochloride, strontium sulfate, strontium nitrate, and strontium acetate. The Ca compound for the anode material layer is not particularly limited, and examples thereof include calcium carbonate, chloride, sulfate, nitrate, and acetate, and preferred are calcium carbonate, calcium oxide, calcium hydroxide, calcium chloride, calcium sulfate, calcium nitrate, and calcium acetate.

[0043] In the anode material layer, the mass ratio of the Ni-containing anode electronically conductive oxide to the perovskite-type proton-conductive oxide (a) (Ni-containing anode electronically conductive oxide:perovskite-type proton-conductive oxide (a)) is not particularly limited, but is preferably 100:0 to 40:60, more preferably 95:5 to 40:60, and more preferably 80:20 to 60:40. When the mass ratio of Ni-containing anode electronically conductive oxide:perovskite-type proton-conductive oxide (a) in the anode material layer (1) is within the above range, the difference in shrinkage rate with the electrolyte that occurs during co-sintering and the porosity of the anode material layer can be adjusted.

[0044] The content of the Ba compound, Sr compound, or Ca compound in the anode material layer is not particularly limited, but is preferably 0.5 to 40.0 mass %, and more preferably 5.0 to 30.0 mass %, relative to the perovskite-type proton-conducting oxide (a) containing any one of Ba, Sr, and Ca. When the content of the Ba compound, Sr compound, or Ca compound in the anode material layer is within the above range, sufficient diffusion of Ba, Sr, or Ca into the electrolyte material layer is promoted, resulting in crystal growth.

[0045] The electrolyte material layer contains a perovskite-type proton-conducting oxide (b) containing, as an A-site element, one of Ba, Sr, and Ca that is the same as the A-site element of the perovskite-type proton-conducting oxide (a) contained in the anode material layer. In other words, the electrolyte material layer is a layered molded body made of a perovskite-type proton-conducting oxide (b) containing, as an A-site element, one of Ba, Sr, and Ca that is the same as the A-site element of the perovskite-type proton-conducting oxide (a) contained in the anode material layer.

[0046] The perovskite-type proton-conducting oxide (b) containing the same A-site element as the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca as the A-site element in the electrolyte material layer is an ABO3-type perovskite-type proton-conducting oxide, and contains at least the same A-site element as the perovskite-type proton-conducting oxide (a) contained in the anode material layer. The perovskite-type proton-conducting oxide (b) also contains at least Zr or Ce as the B-site element, preferably at least Zr. Examples of the perovskite-type proton-conducting oxide (b) include perovskite-type proton-conducting oxides represented by the general formula (I). The perovskite-type proton-conducting oxide represented by the general formula (I) may be a single type or a combination of two or more types, as long as it satisfies the general formula (I). The perovskite-type proton-conducting oxide (b) may be a perovskite-type proton-conducting oxide represented by the general formula (II). The perovskite-type proton-conducting oxide represented by the general formula (II) may be one type or a combination of two or more types, as long as it satisfies the general formula (II).

[0047] The perovskite-type proton-conducting oxide (b) contained in the electrolyte material layer may have the same composition as or a different composition from the perovskite-type proton-conducting oxide (a) contained in the anode material layer.

[0048] Examples of combinations of the perovskite-type proton-conducting oxide (a) contained in the fuel electrode material layer and the perovskite-type proton-conducting oxide (b) contained in the electrolyte material layer include: (i) a perovskite-type proton-conducting oxide (a) containing one of Ba, Sr, and Ca as an A-site element and at least Zr as a B-site element, and a perovskite-type proton-conducting oxide (b) containing the same A-site element as the A-site element of the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca, and containing Zr as a B-site element. (ii) a combination of a perovskite proton-conducting oxide (a) containing one of Ba, Sr, and Ca as an A-site element and at least Ce as a B-site element, and a perovskite proton-conducting oxide (b) containing the same A-site element as the perovskite proton-conducting oxide (a) from the group consisting of Ba, Sr, and Ca, and at least Ce as a B-site element.

[0049] The average particle size of the perovskite-type proton-conductive oxide (b) for the electrolyte material layer is not particularly limited, but is preferably 0.01 to 10 μm, more preferably 0.01 to 4 μm.

[0050] Then, in the raw material layer laminate fabrication step, the anode material layers and the electrolyte material layers are laminated to fabricate a laminate of the electrolyte material layers and the anode material layers.

[0051] The method for producing the laminate of the electrolyte material layer and the anode material layer is not particularly limited, but the following method may be mentioned, for example. (i) First, a slurry dispersion of anode raw materials containing a Ni-containing anode electron conductive oxide, a perovskite-type proton conductive oxide (a), and a compound containing the same A-site element as the perovskite-type proton conductive oxide (a) among Ba, Sr, and Ca is tape-cast and dried to obtain anode material layer green sheets. A slurry dispersion of electrolyte raw materials containing a perovskite-type proton conductive oxide (b) containing the same A-site element as the perovskite-type proton conductive oxide (a) among Ba, Sr, and Ca is tape-cast and dried to obtain an electrolyte material layer green sheet. Next, one or more anode material layer green sheets and one or more electrolyte material layer green sheets are stacked to a predetermined thickness and heated and pressed to produce a laminate of electrolyte material layers and anode material layers. (ii) First, a slurry of anode raw materials containing an anode electron conductive oxide containing Ni, a perovskite-type proton conductive oxide (a), and a compound containing the same A-site element as the perovskite-type proton conductive oxide (a) among Ba, Sr, and Ca is tape-cast and dried to obtain a green sheet for the anode material layer. Next, one or more anode material layer green sheets are stacked to a predetermined thickness and heated and pressed to produce an anode material layer. Next, a slurry of electrolyte raw materials containing a perovskite-type proton conductive oxide (b) containing the same A-site element as the perovskite-type proton conductive oxide (a) among Ba, Sr, and Ca is spin-coated onto the anode material layer and dried to produce a laminate of the electrolyte material layer and the anode material layer.

[0052] In the laminate of the electrolyte material layer and the anode material layer, the thickness of the electrolyte material layer is 1 to 30 μm, preferably 1 to 10 μm, and in the laminate of the electrolyte material layer and the anode material layer, the thickness of the anode material layer is 100 to 2000 μm, preferably 300 to 1000 μm.

[0053] The firing step in the method for producing a laminate of an electrolyte and an anode of the present invention is a step of firing a laminate of an electrolyte material layer and an anode material layer at 1150 to 1700° C. to obtain a laminate of an electrolyte and an anode.

[0054] In the method for producing a laminate of an electrolyte and anode according to the present invention, the particle size and density of the crystal particles constituting the electrolyte of the laminate of an electrolyte and anode obtained by the firing step vary depending on the mass ratio of the Ni-containing electron-conductive oxide for the anode to the perovskite-type proton-conductive oxide (a) in the anode material layer (1), the content of the compound containing the same element as the A-site element of the perovskite-type proton-conductive oxide (a) among Ba, Sr, and Ca, the type of the B-site element of the perovskite-type proton-conductive oxide (b) in the electrolyte material layer, and the firing temperature and firing time in the firing step. Therefore, in the firing step, it is preferable to appropriately select the firing temperature and firing time in accordance with the mass ratio of the Ni-containing anode electron conductive oxide to the perovskite-type proton-conducting oxide (a) in the anode material layer, the content of the compound containing the same element as the A-site element of the perovskite-type proton-conducting oxide (a) among Ba, Sr, and Ca, and the type of B-site element of the perovskite-type proton-conducting oxide (b) in the electrolyte material layer, so that the crystal particles have the desired particle size and the electrolyte has the desired density. For example, when the B-site element of the perovskite-type proton-conducting oxide (b) is Zr, the firing temperature is preferably 1150 to 1700°C, more preferably 1250 to 1550°C. Furthermore, for example, when the B-site element of the perovskite-type proton-conductive oxide (b) is Ce, the firing temperature is preferably 1150 to 1700°C, more preferably 1200 to 1450°C.

[0055] The firing atmosphere in the firing step is an air atmosphere.

[0056] In the method for producing a laminate of an electrolyte and an anode of the present invention, the laminate of the electrolyte material layer and the anode material layer can be placed on a setter, and the laminate of the electrolyte material layer and the anode material layer can be fired in a state in which the anode material layer is in contact with the surface of the setter.

[0057] In the method for producing a laminate of an electrolyte and an anode of the present invention, when a setter is used, the anode material layer is in contact with the setter, and the setter is preferably a material through which Ni and an A-site element of the perovskite-type proton-conducting oxide (a) contained in the anode material layer, selected from Ba, Sr, and Ca, can diffuse or penetrate, since this increases the particle size of the crystal particles of the perovskite-type proton-conducting oxide (b) constituting the electrolyte obtained by the firing step and enhances the effect of densifying the electrolyte.

[0058] Examples of the material setter into which the A-site elements of the perovskite-type proton-conducting oxide (a) contained in the fuel electrode material layer, among Ba, Sr, and Ca, and Ni can diffuse include perovskite-type proton-conducting oxides containing the same elements as the A-site elements of the perovskite-type proton-conducting oxide (a) contained in the fuel electrode material layer, preferably perovskite-type proton-conducting oxides of the same type as the perovskite-type proton-conducting oxide (a) contained in the fuel electrode material layer, and also include yttria-stabilized zirconia, calcium-stabilized zirconia, etc. Furthermore, examples of materials into which the liquid phase of the A-site elements of the perovskite-type proton-conductive oxide (a) contained in the anode material layer and Ni can permeate include porous materials such as porous Al2O3 and porous ZrO2.

[0059] In the method for producing a laminate of an electrolyte and an anode according to the present invention, by incorporating into the anode material layer a compound containing the same A-site element of the perovskite-type proton-conducting oxide (a) contained in the anode material layer, selected from Ba, Sr, and Ca, the particle size of the crystal particles of the perovskite-type proton-conducting oxide (b) constituting the electrolyte obtained by the firing step can be increased and the electrolyte can be made denser, compared to when the anode material layer does not contain a compound containing the same A-site element of the perovskite-type proton-conducting oxide (a) contained in the anode material layer, selected from Ba, Sr, and Ca. Therefore, the method for producing a laminate of an electrolyte and an anode according to the present invention can increase the proton conductivity of the electrolyte, thereby improving the proton transport number, power generation characteristics, mechanical strength, and gas sealing ability of a proton-conducting solid oxide cell.

[0060] The electrolyte for a proton-conducting solid oxide cell of the present invention is an electrolyte formed of crystal particles of a perovskite-type proton-conducting oxide, which contains Ba as an A-site element and Zr as a B-site element, and in which the content of Ce in atomic terms relative to all B-site elements is 10.0 mol % or less, In a scanning electron microscope (SEM) image, the average particle size of the crystal particles is 1.5 to 5.0 μm; the Ni content in the electrolyte is 0.80 at% or less; The present invention relates to an electrolyte for a proton-conducting solid oxide cell, characterized in that:

[0061] The electrolyte for a proton-conducting solid oxide cell of the present invention is formed from crystalline particles of a perovskite-type proton-conducting oxide containing Ba as an A-site element and Zr as a B-site element.

[0062] The perovskite-type proton-conducting oxide according to the present invention, which is an electrolyte for a proton-conducting solid oxide cell, is an ABO3-type perovskite-type proton-conducting oxide containing Ba as an A-site element and Zr as a B-site element, with a Ce atomic content of 10.0 mol % or less relative to all B-site elements. The Ce atomic content of the perovskite-type proton-conducting oxide according to the present invention, which is an electrolyte for a proton-conducting solid oxide cell, is preferably 3.0 mol % or less, more preferably 0.5 mol % or less, and more preferably 0.0 mol %.

[0063] The perovskite-type proton-conducting oxide for the electrolyte of the proton-conducting solid oxide cell of the present invention is a proton-conducting oxide represented by the following general formula (III): Ba x3 (Zr α3 Ce β3 A3 (1-α3-β3) ) y3 O 3-z3 (III) (In formula (III), A3 is at least one of a trivalent or tetravalent element, x3 is 0.90 to 1.10, α3 is 0.10 to 1.00, β3 is 0.00 to 0.10, y3 is 0.90 to 1.10, and z3 is 0.00 to 0.50.) Examples of the perovskite-type proton-conducting oxide include those represented by the following formula:

[0064] In general formula (III), A3 is at least one of Ti, Hf, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc, preferably at least one of Ce, Y, and Yb, and more preferably Yb. x3 is 0.90 to 1.10, preferably 0.96 to 1.05, and more preferably 0.98 to 1.01. α3 is 0.10 to 1.00, preferably 0.50 to 0.95, more preferably 0.70 to 0.90, and more preferably 0.75 to 0.85. β3 is 0.10 or less, preferably 0.03 or less, more preferably 0.005 or less, and more preferably 0.00. y3 is 0.90 to 1.10, preferably 0.96 to 1.05, and more preferably 0.98 to 1.01. z3 is 0.00 to 0.40, preferably 0.00 to 0.30, and more preferably 0.00 to 0.15. When A3 is two or more elements, the value of 1-α3-β3 is the total value of those two or more elements, and the value of y3 is the total value of Zr, Ce, and those two or more elements. The perovskite-type proton-conducting oxide represented by general formula (III) may be one type or a combination of two or more types, as long as it satisfies general formula (III).

[0065] In the electrolyte for a proton-conducting solid oxide cell of the present invention, the average particle size of the crystal particles of the perovskite-type proton-conducting oxide is 1.5 to 5.0 μm, preferably 2.0 to 5.0 μm, and more preferably 2.5 to 4.5 μm in a scanning electron microscope (SEM) image. Furthermore, from the viewpoint of proton conductivity, the average particle size of the crystal particles of the perovskite-type proton-conducting oxide is preferably approximately the same as the membrane thickness. When the average particle size of the crystal particles of the perovskite-type proton-conducting oxide is within the above range, the proton conductivity of the electrolyte is increased.

[0066] In the electrolyte for a proton-conductive solid oxide cell of the present invention, the standard deviation in the particle size distribution curve of the crystal particles of the perovskite-type proton-conductive oxide in a scanning electron microscope (SEM) image is 0.25 to 1.20 μm, preferably 0.30 to 1.20 μm.

[0067] In the present invention, the average particle size and standard deviation in the particle size distribution curve of crystal particles of a perovskite-type proton-conductive oxide are determined by the following procedure. First, an electrolyte for a proton-conductive solid oxide cell is photographed using a scanning electron microscope to obtain an SEM image. Next, 20 particles are randomly selected from the obtained SEM image, and the major axis of each selected particle is measured. The obtained major axis data for the 20 particles is fitted with a Gaussian to determine the average particle size and standard deviation.

[0068] The Ni content in the electrolyte for a proton-conducting solid oxide cell of the present invention is 0.80 at% or less, preferably 0.30 at% or less, and more preferably 0.10 at% or less. When the Ni content in the electrolyte for a proton-conducting solid oxide cell is within the above range, the proton conductivity is improved. On the other hand, if the Ni content in the electrolyte exceeds the above range, grain growth proceeds, improving sinterability and densification, but the proton conductivity is reduced.

[0069] The content of the sintering aid in the electrolyte for a proton-conducting solid oxide cell of the present invention is preferably 0.50 at% or less, more preferably 0.10 at% or less, and more preferably 0.00 at%. In other words, the electrolyte for a proton-conducting solid oxide cell of the present invention preferably does not contain a sintering aid. Examples of sintering aids include transition metals such as Zn, Cu, Mg, Ni, Co, Fe, Nb, Mo, and Mn, and oxides containing these metals. By having the content of the sintering aid in the electrolyte for a proton-conducting solid oxide cell within the above range, the proton conductivity is improved. No sintering aids are used in the production of the electrolyte for a proton-conducting solid oxide cell of the present invention. Therefore, even if compounds contained in the electrolyte for a proton-conducting solid oxide cell due to diffusion from other ingredients or the like serve as sintering aids, the content of such compounds in the electrolyte for a proton-conducting solid oxide cell of the present invention is preferably 0.50 at% or less, more preferably 0.10 at% or less, and more preferably 0.00 at%.

[0070] The thickness of the electrolyte for the proton-conducting solid oxide cell of the present invention is 1 to 30 μm, preferably 1 to 10 μm.

[0071] The method for producing the electrolyte for a proton-conductive solid oxide cell of the present invention is not particularly limited, but it is suitably produced by the method for producing a laminate of an electrolyte for a proton-conductive solid oxide cell and an anode according to the first embodiment of the present invention.

[0072] The proton-conducting solid oxide cell of the present invention is a proton-conducting solid oxide cell characterized by having the electrolyte for the proton-conducting solid oxide cell of the present invention.

[0073] The proton-conducting solid oxide cell of the present invention has an anode, an electrolyte, and an air electrode, the anode, the electrolyte, and the air electrode being stacked in this order, and the electrolyte is the electrolyte for the proton-conducting solid oxide cell of the present invention. The proton-conducting solid oxide cell of the present invention can also have an intermediate layer between the anode and the electrolyte or between the electrolyte and the air electrode.

[0074] The anode of the proton-conducting solid oxide cell of the present invention is not particularly limited as long as it is a cathode used in a proton-conducting solid oxide cell. For example, the anode may be formed from an anode oxide or from an anode oxide and a proton-conducting oxide. In addition to the anode oxide, the anode may contain an electron-conducting oxide, a proton-conducting oxide, an oxide-ion-conducting oxide, alumina for adjusting the thermal expansion coefficient, or the like, as long as the effects of the present invention are not impaired.

[0075] The perovskite-type oxide for the anode used in the anode may be one type or a combination of two or more types. When a proton-conductive oxide is used in the anode, the proton-conductive oxide may be one type or a combination of two or more types.

[0076] In the fuel electrode, the mass ratio of the fuel electrode oxide to the proton-conductive oxide (fuel electrode oxide:proton-conductive oxide) is preferably 100:0 to 40:60, more preferably 95:5 to 40:60, and more preferably 80:20 to 60:40. When the mass ratio of the fuel electrode oxide to the proton-conductive oxide in the fuel electrode is within the above range, the electrode resistance can be low and the power density can be increased.

[0077] The electrolyte and the fuel electrode of the proton-conducting solid oxide cell of the present invention are preferably the electrolyte and the fuel electrode manufactured by the method for manufacturing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell of the present invention, in that the effect of increasing proton conductivity is enhanced.

[0078] The air electrode and the intermediate layer provided as needed in the proton-conducting solid oxide cell of the present invention are not particularly limited as long as they are the air electrode and intermediate layer used in proton-conducting solid oxide cells.

[0079] In the proton-conducting solid oxide cell of the present invention, the air electrode material used to fabricate the air electrode is primarily composed of an electronically conductive oxide for the air electrode of the proton-conducting solid oxide cell. The air electrode electronically conductive oxide used to form the air electrode may be one type or a combination of two or more types. Furthermore, the air electrode material may contain electronically conductive oxides other than the air electrode electronically conductive oxide, proton-conducting oxides, oxide-ion-conducting oxides, alumina for adjusting the thermal expansion coefficient, etc., within the scope of the present invention.

[0080] The content of the cathode electronically conductive oxide in the cathode material is 30.0 mass% or more, preferably 50.0 mass% or more, more preferably 70.0 mass% or more, and particularly preferably 100.0 mass%. When the content of the cathode electronically conductive oxide in the cathode material is within the above range, the cathode resistance is low and the power density can be increased.

[0081] The electron conductive oxide for the air electrode is not particularly limited, but may be, for example, an oxide represented by the following general formula (5): A5 (1-x5) B5 x5 C5 y5 O 3-z5 (5) A perovskite oxide material represented by the following formula is preferred.

[0082] In general formula (5), A5 is one or more of Y, La, Ce, Pr, Sm, and Gd, preferably one or more of La, Sm, and Gd. B5 is one or more of Sr, Ca, and Ba, preferably Sr. C5 is one or more of Cr, Mn, Fe, Co, Ni, and Cu, preferably one or more of Mn, Fe, and Co. x5 is 0.20 to 0.60, preferably 0.25 to 0.50, and particularly preferably 0.30 to 0.50. y5 is 0.95 to 1.15, preferably 1.00 to 1.10, and particularly preferably 1.00 to 1.05. z5 is -1.00 to 1.00, preferably -0.50 to 0.50, and particularly preferably -0.30 to 0.30.

[0083] Examples of the electron conductive oxide for the air electrode include oxides such as (LaBa)MnO3, (LaBa)FeO3, (LaBa)CoO3, (LaBa)(CoFe)O3, and (BaSr)(CoFe)O3.

[0084] In the air electrode material used to fabricate the air electrode, the mass ratio of the air electrode electronically conductive oxide to the proton-conductive oxide (air electrode electronically conductive oxide:proton-conductive oxide) is 90:10 to 10:90, preferably 75:25 to 25:75, and particularly preferably 60:40 to 40:60. When the mass ratio of the air electrode electronically conductive oxide to the proton-conductive oxide in the air electrode is within the above range, the number of contact points between the air electrode electronically conductive oxide and the proton-conductive oxide increases, expanding the reaction field, lowering the electrode resistance and increasing the current density.

[0085] In the proton-conducting solid oxide cell of the present invention, the intermediate layer material used to prepare the intermediate layer is mainly represented by the following general formula (6): A6x6 B6 y6 O 3+z6 (6) (In formula (6), A6 is at least one of Ca, Sr, Ba, and La; B6 is at least one of Sc, Ga, Y, Zr, In, Ce, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Hf; x6 is 0.80 to 1.20; y6 is 0.80 to 1.20; and z6 is −0.80 to +0.80.) Since the intermediate layer material is mainly made of the perovskite-type proton-conducting oxide represented by general formula (6), it has high proton conductivity and high chemical stability, and therefore can achieve high power density and durability.

[0086] In the general formula (6), A6 is at least one of Ca, Sr, Ba and La, and is preferably Ba. B6 is at least one of Sc, Ga, Y, Zr, In, Ce, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Hf, and preferably at least one of Y, Zr, Ce, and Yb. x6 is 0.80 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. y6 is 0.80 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. z6 is −0.80 to +0.80, preferably −0.40 to +0.40, and more preferably −0.20 to +0.00. If A6 is two or more elements, the value of x6 is the total value of those two or more elements. If B6 is two or more elements, the value of y4 is the total value of those two or more elements.

[0087] The perovskite-type proton-conducting oxide represented by the general formula (6) may be one type or a combination of two or more types, as long as it satisfies the general formula (6).

[0088] The intermediate layer material may contain a proton-conductive oxide other than the perovskite-type proton-conductive oxide represented by general formula (6), an electron-conductive oxide, an oxide-ion-conductive oxide, alumina for adjusting the thermal expansion coefficient, etc., within the range that does not impair the effects of the present invention.

[0089] The content of the perovskite-type proton-conductive oxide represented by general formula (6) in the intermediate layer material is 80.0 mass% or more, preferably 90.0 mass% or more, more preferably 95.0 mass% or more, and particularly preferably 100.0 mass%. When the content of the perovskite-type proton-conductive oxide represented by general formula (6) in the intermediate layer material is within the above range, the air electrode resistance can be low and the power density can be increased.

[0090] In the proton-conducting solid oxide cell of the present invention, the air electrode or intermediate layer is formed, for example, by preparing a slurry in which at least a powdered air electrode material or a powdered intermediate layer material is dispersed, then applying the slurry to an object to be formed to form a slurry coating film and mold it into a layer, then drying it to produce an air electrode material layer or an intermediate layer material layer, and then firing it at a firing temperature, for example, 700 to 1400°C, for sintering.

[0091] The proton-conducting solid oxide cell of the present invention uses the electrolyte for proton-conducting solid oxide cells of the present invention as the electrolyte, and therefore the average particle size of the crystal particles of the proton-conducting oxide forming the electrolyte is larger than that of conventional proton-conducting solid oxide cells, making the electrolyte denser. Therefore, the proton-conducting solid oxide cell of the present invention has a higher proton conductivity of the electrolyte than conventional proton-conducting solid oxide cells, and the proton-conducting transport number and power generation characteristics are improved. Furthermore, the increased density improves durability and gas sealing properties. [Example]

[0092] Next, the present invention will be described in more detail with reference to examples, but these are merely illustrative and do not limit the present invention.

[0093] (Manufacturing example) (1) Synthesis of battery materials <50 parts by mass La 0.6 Ba 0.4 CoO 3.0 -50 parts by mass BaZr 0.9 Yb 0.1 O3> (Synthesis of oxide powder materials for air electrodes by spray pyrolysis) Spray pyrolysis is one of the methods for synthesizing nano-sized oxide powder materials. While it is possible to synthesize a single oxide powder material, it is also possible to synthesize oxide powder materials that are composites of two or more oxides. In this case, a good dispersion state can be obtained for the composites of two or more oxides. Another feature is that the primary particle size can be controlled over a wide range. Below, we will describe the synthesis of oxide powder materials for air electrodes using spray pyrolysis.

[0094] The spray pyrolysis process involves preparing an aqueous solution for spraying containing a metal salt of a source of an electron-conductive material for the air electrode and a metal salt of a source of a proton-conductive material, atomizing the aqueous solution for spraying by ultrasonic vibration, and then introducing the atomized aqueous solution for spraying into a heating furnace to obtain an oxide powder material for the air electrode.

[0095] The aqueous solution to be sprayed in the spraying device was atomized by ultrasonic vibration (1.75 MHz), and then the atomized aqueous solution to be sprayed was introduced into a heating furnace through a pipe connected to the spraying device. The metal salt of the source of the electron conductive material for the air electrode and the metal salt of the source of the proton conductive material in the aqueous solution to be sprayed were thermally decomposed and oxidized to obtain an oxide powder material for the air electrode. A four-stage electric furnace (furnace temperatures from the front stage: 300, 500, 700, and 900°C, heating times from the front stage: 8 seconds, 8 seconds, 8 seconds, and 8 seconds) was used as the heating furnace.

[0096] (Preparation of aqueous solution for spraying) Lanthanum nitrate hexahydrate (6.96 g), barium nitrate (8.87 g), cobalt nitrate hexahydrate (7.80 g), zirconium nitrate oxide dihydrate (5.58 g), and ytterbium nitrate pentahydrate (1.04 g) were weighed and dissolved in pure water. Further pure water was added to make the total volume of the solution 1000 ml, to prepare an aqueous solution for spraying. The aqueous solution for spraying was subjected to spray pyrolysis to obtain 50 parts by mass of 0.05 mol of La per 1 L. 0.6 Ba 0.4 CoO 3.0 (LBC)-50 parts by mass BaZr 0.9 Yb 0.1 O3(BZYb10) can be synthesized.

[0097] (Preparation of oxide powder material for air electrodes) The sprayed aqueous solution was used to carry out spray pyrolysis by ultrasonic spray pyrolysis to obtain an oxide powder material for an air electrode of LBC-BZYb10.

[0098] When the oxide powder material for a cathode was subjected to X-ray diffraction analysis, diffraction peaks identifiable as LBC and BZYb were observed, confirming that the powder material contained crystalline LBC and BZYb10.

[0099] <BaZr 0.8 Yb 0.2 O3(BZYb)> Made by Kusaka Rare Metals Research Institute

[0100] <50 parts by mass Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3.0 -50 parts by mass BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O3(BSCF-BCZYYb)> <Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3.0 (BSCF)> Made by Kusaka Rare Metals Research Institute <BaCe 0.7 Zr0.1 Y 0.1 Yb 0.1 O3(BCZYYb)> DOWA Electronics Co., Ltd.

[0101] Example 1 <Preparation of a laminate of electrolyte and fuel electrode> NiO and BaZr 0.8 Yb 0.2 O3, Ba(CO3) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and carbon were mixed in a mass ratio of 60:40:2:10, and a toluene-based solvent, binder, plasticizer, and dispersant were added. The mixture was then mixed in a ball mill for 48 hours to obtain a slurry for the anode. The slurry for the anode was tape-cast to obtain a green sheet for the anode. The green sheets for the anode were laminated to a thickness of approximately 0.9 mm, and the thickness of the green sheet for the anode was adjusted. BaZr 0.8 Yb 0.2 Toluene-based solvent, binder, plasticizer, and dispersant were added to O3 and mixed in a ball mill for 48 hours to obtain electrolyte slurry, which was then tape-cast to obtain electrolyte green sheets. Next, the electrolyte sheet was placed on the anode green sheet and hot pressed. The resulting laminate was then co-sintered at 1200°C for 3 hours to obtain a laminate of electrolyte and anode. The electrolyte in the resulting laminate was densified by the high-temperature co-sintering.

[0102] Example 2 In Example 2, the co-sintering conditions of Example 1 were changed to 1300° C. for 3 hours.

[0103] Example 3 In Example 3, the co-sintering conditions of Example 1 were changed to 1400° C. for 3 hours.

[0104] Example 4 In Example 4, the co-sintering conditions of Example 1 were changed to 1500° C. for 3 hours.

[0105] Example 5 In Example 5, the co-sintering conditions of Example 1 were changed to 1500° C. for 7 hours.

[0106] Example 6 In Example 6, the co-sintering conditions of Example 1 were changed to 1500°C for 11 hours.

[0107] Example 7 In Example 7, NiO and BaZr 0.8 Yb 0.2 The mass ratio of O3, Ba(CO3), and carbon was changed to 60:40:4:10, and the co-sintering conditions were changed to 1300°C for 3 hours.

[0108] Example 8 In Example 8, the co-sintering conditions of Example 7 were changed to 1400°C for 3 hours.

[0109] Example 9 In Example 9, the co-sintering conditions of Example 7 were changed to 1500°C for 3 hours.

[0110] Example 10 In Example 10, NiO and BaZr 0.8 Yb 0.2 The mass ratio of O3, Ba(CO3), and carbon was changed to 80:20:2:10, and the co-sintering conditions were changed to 1400°C for 3 hours.

[0111] Example 11 In Example 11, the co-sintering conditions of Example 10 were changed to 1500° C. for 3 hours.

[0112] Example 12 In Example 12, the co-sintering conditions of Example 10 were changed to 1500°C for 7 hours.

[0113] Example 13 In Example 13, the co-sintering conditions of Example 10 were changed to 1500°C for 11 hours.

[0114] Example 14 In Example 14, NiO and BaZr0.8 Yb 0.2 The mass ratio of O3, Ba(CO3), and carbon was changed to 80:20:6:10, and the co-sintering conditions were changed to 1500°C for 3 hours.

[0115] Example 15 In Example 15, the co-sintering conditions of Example 14 were changed to 1500°C for 7 hours.

[0116] Example 16 In Example 16, the co-sintering conditions of Example 14 were changed to 1500°C for 11 hours.

[0117] (Comparative Example 1) <Preparation of a laminate of electrolyte and fuel electrode> In Comparative Example 1, Ba(CO3) in Example 1 was not mixed, and NiO and BaZr 0.8 Yb 0.2 O3 and carbon alone were mixed in a ratio of 60:40:10 and co-sintered at 1300°C for 3 hours.

[0118] (Comparative Example 2) In Comparative Example 2, the co-sintering conditions of Comparative Example 1 were changed to 1400° C. for 3 hours.

[0119] (Comparative Example 3) In Comparative Example 3, the co-sintering conditions of Comparative Example 1 were changed to 1500° C. for 3 hours.

[0120] <Measurement of the average particle size of crystal particles and the standard deviation of the particle size distribution curve> The electrolyte in the electrolyte / anode stack was photographed with a scanning electron microscope (magnification: 5000x) to obtain an SEM image. The results are shown in Figure 2. By using this method, crystal grains grow as the temperature rises, and pinholes disappear. Next, the electrolyte in the stack of electrolyte and anode was photographed with a scanning electron microscope (magnification: 500x) to obtain an SEM image. The results are shown in Figure 3. By using this method, the generation of impurities in Yb2O3 generated in Comparative Example 3 is suppressed by adding BaCO3 to the anode. Next, 20 particles were randomly selected from the SEM image and the major axis of each particle was measured. The major axis data for the 20 particles were then fitted with a Gaussian function to obtain a particle size distribution curve. The results are shown in Figure 4. The average particle size of the crystal particles and the standard deviation of the particle size distribution curve were determined, and as a result, in Example 7, the average particle size of the crystal particles was 2.10 μm, and the standard deviation of the particle size distribution curve was 0.28 μm, in Example 9, the average particle size of the crystal particles was 3.82 μm, and the standard deviation of the particle size distribution curve was 0.83 μm, and in Example 4, the average particle size of the crystal particles was 4.10 μm, and the standard deviation of the particle size distribution curve was 1.09 μm.

[0121] <Gaussian fitting> (1 / (2πσ) 1 / 2 )exp(-(x-μ) 2 / 2σ 2 ) where μ corresponds to the average particle size and σ corresponds to the standard deviation.

[0122] <Measurement of Ni concentration after co-sintering> The electrolytes of the laminates of electrolytes and anodes obtained in Examples 1 to 16 were photographed with a scanning electron microscope (magnification: 500x), and the composition of the entire image was measured by EDS at 15 kV for 1 minute 20 seconds. The results are shown in Figure 5. The Ni concentration decreased due to high-temperature firing, and the Ni concentration was 0.8 mol% (at%) or less in atomic terms under almost all conditions.

[0123] <Evaluation of proton conductivity> The half-cells of Examples 4, 5, 6, and Comparative Example 3 were thoroughly reduced at 700°C in a hydrogen atmosphere, and then a Pd film of approximately 100 nm was formed on the electrolyte side and fuel electrode side by sputtering over an area of ​​φ5 mm. Further contact with the electrodes was achieved using Ag paste. Measurements were performed up to 650°C at approximately 30% humidity using a Bio-Logic SAS SP-300 / 240. The results are shown in Figure 6. It was confirmed that the proton conductivity characteristics of Examples 4, 5, and 6 were improved by a factor of just under two.

[0124] <Fabrication of proton-conducting solid oxide cell 1> The LBC-BZYb10 (50 parts by mass La 0.6 Ba 0.4 CoO 3.0 -50 parts by mass BaZr 0.9 Yb 0.1 Ethyl cellulose, a plasticizer, a dispersant, and α-terpineol were added to O3) and mixed in a mixer at room temperature for 4 minutes to obtain a slurry for the air electrode. Next, the slurry for the air electrode was applied to the electrolyte of the laminate of the electrolyte and the fuel electrode obtained in Example 15 by screen printing using a 20 μm mesh to a diameter of φ6 mm, followed by firing at 900° C. for 1 hour to obtain an air electrode. In this way, a proton-conducting solid oxide cell 1 was obtained.

[0125] <Fabrication of proton-conducting solid oxide cell 2> The BSCF-BCZYYb (50 parts by mass Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3.0 -50 parts by mass BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 Ethyl cellulose, a plasticizer, a dispersant, and α-terpineol were added to O3) and mixed in a mixer at room temperature for 4 minutes to obtain a slurry for the air electrode. Next, the slurry for the air electrode was applied to the electrolyte of the laminate of the electrolyte and the fuel electrode obtained in Example 13 by screen printing using a 20 μm mesh to a diameter of φ6 mm, followed by firing at 900° C. for 2 hours to obtain an air electrode. In this way, a proton-conducting solid oxide cell 2 was obtained.

[0126] <Performance evaluation of proton-conducting solid oxide cells 1 and 2> For the proton-conducting ceramic cell, an electrochemical measurement system (potentiostat / galvanostat, VSP, Biologic) was used to supply humidified hydrogen at 25°C to the fuel electrode and humidified air at 25°C to the air electrode, and current-voltage characteristics and electrochemical impedance measurements were performed at 600°C. The maximum power density was calculated from the results of the current-voltage characteristics measurements. The results are shown in Figure 7.

[0127] In FIG. 7, both Example 15 and Example 13 are graphs showing the temperatures from highest to lowest maximum power density: 700°C, 650°C, 600°C, 550°C, and 500°C. [Explanation of symbols]

[0128] 1 Electrolyte material layer 2 Material layer for fuel electrode 3 Setter 4. Laminate of electrolyte material layer and fuel electrode material layer [Industrial Applicability]

[0129] By using the present invention, it is possible to manufacture a proton-conducting solid oxide cell with high power generation performance due to the high proton conductivity of the electrolyte.

Claims

1. a perovskite-type proton-conducting oxide (b) containing, as an A-site element, one of Ba, Sr, and Ca that is the same as the A-site element of the perovskite-type proton-conducting oxide (a), and a compound containing the same element as the A-site element of the perovskite-type proton-conducting oxide (a), selected from Ba, Sr, and Ca; and an electrolyte material layer containing a perovskite-type proton-conducting oxide (b) containing, as an A-site element, the same element as the A-site element of the perovskite-type proton-conducting oxide (a), selected from Ba, Sr, and Ca; and a firing step of firing the laminate of the electrolyte material layer and the anode material layer at 1150 to 1700°C to obtain a laminate of the electrolyte and the anode.

2. 2. A method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell according to claim 1, wherein the perovskite-type proton-conducting oxide (a) is a perovskite-type proton-conducting oxide containing Zr as a B-site element, and the perovskite-type proton-conducting oxide (b) is a perovskite-type proton-conducting oxide containing Zr as a B-site element.

3. the anode material layer is formed on a setter, the setter is a material through which the same elements as the A-site elements of the perovskite-type proton-conducting oxide (a), among Ba, Sr and Ca, and Ni can diffuse or penetrate; 2. A method for producing a laminate of an electrolyte and a fuel electrode for a proton-conducting solid oxide cell according to claim 1,

4. an electrolyte formed of crystal particles of a perovskite-type proton-conducting oxide containing Ba as an A-site element and Zr as a B-site element, and in which the content of Ce in atomic terms relative to all B-site elements is 10.0 mol % or less; In a scanning electron microscope (SEM) image, the average particle size of the crystal particles is 1.5 to 5.0 μm; the content of Ni in the electrolyte is 0.80 at% or less; 1. An electrolyte for a proton-conducting solid oxide cell, comprising:

5. 5. The electrolyte for a proton-conducting solid oxide cell according to claim 4, wherein the content of the sintering aid is 0.50 at % or less.

6. 5. A proton-conducting solid oxide cell comprising the electrolyte for a proton-conducting solid oxide cell according to claim 4.

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