Electrolyte layer for proton-conducting ceramic cell, electrolyte for proton-conducting ceramic cell, proton-conducting ceramic cell, and method for manufacturing a proton-conducting ceramic cell

Abstract

To provide an electrolyte for proton-conducting ceramic cells that can improve the power generation performance of the proton-conducting ceramic cell. [Solution] A1 x1 B1 y1 O 3+z1 (A1 is at least one of Ca, Sr, and Ba, and B1 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, with Ce accounting for 30 mol% or more of B1.) The perovskite-type proton-conducting oxide is composed of such an oxide, and the average lattice constant in the wet state from the 0% position to the X% position in the thickness direction is A X When B is the lattice constant of a powdered perovskite-type proton-conducting oxide in its wet state, having the same composition as the composition at the 50% position in the thickness direction, ((A X An electrolyte layer for proton-conducting ceramic cells, wherein -B) / B)×100 is -0.05% to +0.15% at X=50 to 90.

Description

[Technical Field]

[0001] The present invention relates to an electrolyte layer, an electrolyte, a proton-conducting ceramic cell using the same, and a method for manufacturing a proton-conducting ceramic cell. [Background technology]

[0002] Solid oxide cells for electrochemical reactions are being researched and developed for practical use by ceramic manufacturers, the energy industry, the automotive industry, and others, as devices that enable highly efficient energy conversion. For example, they are applied to 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 electrolytic cells. Solid oxide cells are constructed by sandwiching a dense electrolyte, mainly made of oxides, between two porous electrodes: an air electrode and a fuel electrode. Depending on the constituent materials, these solid oxide cells can be used in a wide operating temperature range of 400 to 1000°C.

[0004] The electrode material used is an electron-conducting oxide or metal with catalytic activity (hereinafter referred to as "electron-conducting material"). While electron-conducting materials are sometimes used individually, to expand the reaction field within the electrode, they are sometimes mixed with an ionic conductive material that conducts the same material as the electrolyte or the same ions as the electrolyte ("ions" is a general term for all ions that act as conduction carriers, including oxide ions and protons). Generally, mixing electron-conducting materials and ionic conductive materials reduces the reaction resistance of the electrode. The reaction resistance depends on the size of the reaction field per unit area of ​​the electrode (or the amount of reaction active sites) and the activity per reaction field.

[0005] Solid oxide fuel cells include those in which the ions serving as charge carriers are mainly oxide ions and protons. Among solid oxide cells, proton-conducting ceramic cells are those in which the ions serving as charge carriers are mainly protons. In proton-conducting ceramic cells, the material that conducts protons is called a proton-conducting electrolyte. Perovskite-type oxide materials and the like are cited as typical examples of proton-conducting electrolytes.

[0006] Compared with oxide ion-conducting ceramic cells, when proton-conducting ceramic fuel cells are used as fuel cells, water vapor is not generated at the fuel electrode, so the fuel utilization rate can be increased; when used as an electrolysis cell, hydrogen is discharged to the fuel electrode side, so the hydrogen concentration can be increased, which has the advantage of high energy conversion efficiency. In addition, due to the low activation energy of proton conduction, it has the advantage of being usable at a lower operating temperature than oxide ion-conducting ceramic fuel cells.

[0007] For the popularization and commercialization of proton-conducting ceramic fuel cells, it is necessary to achieve high cell current density. Reducing electrolyte resistance is one of the methods for increasing the cell current density. Therefore, in the development of proton-conducting ceramic fuel cells, in addition to increasing the output (maximum output density), it has become important to develop proton-conducting ceramic fuel cells that can reduce electrolyte resistance.

[0008] For example, in Non-Patent Document 1, the electrolyte is BaZr 0.8 Yb 0.2 O 3- δ-BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3- It has been proposed that by using a two-layer electrolyte of δ, electrolyte performance can be improved.

[0009] In addition, in Non-Patent Document 2, the electrolyte is BaZr 0.8 Y 0.2 O 3- δ-BaZr 0.1 Ce0.7 Y 0.1 Yb 0.1 O 3- It has been proposed to improve electrolyte performance by using a two-layer δ electrolyte. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] Ceramics International 50(2024), 40579-40585 [Non-Patent Document 2] Journal of The Electrochemical Society, 2023 170 124520 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, while Non-Patent Documents 1 and 2 show some improvement in power generation performance, further performance improvements are needed.

[0012] Therefore, the present invention aims to provide an electrolyte for proton-conducting ceramic cells that can improve the power generation performance of the proton-conducting ceramic cells. [Means for solving the problem]

[0013] The present inventors, through diligent research to solve the above problems, have found that the electrolyte has a two-layer structure consisting of a first electrolyte layer made of a perovskite-type proton-conducting oxide in which Ce is the main element of the B site on the air electrode side, and a second electrolyte layer made of a perovskite-type proton-conducting oxide in which Zr is the main element of the B site on the fuel electrode side. By making the thickness of the first electrolyte layer on the air electrode side larger and the thickness of the second electrolyte layer on the fuel electrode side smaller, and setting the ratio within a predetermined range, during the formation of the electrolyte by firing, (1) the second electrolyte layer on the fuel electrode side suppresses the diffusion of Ni from the fuel electrode to the first electrolyte layer on the air electrode side, and the B site of the perovskite-type proton-conducting oxide forming the electrolyte on the air electrode side is replaced with Ni, which has a smaller ionic radius. (1) The decrease in the lattice constant is suppressed, and the lattice constant of the second electrolyte layer near the first electrolyte layer increases due to Ce diffusing from the first electrolyte layer, so the average lattice constant of the entire electrolyte layer on the fuel electrode side does not decrease, or even increases. (2) Because the thickness of the first electrolyte layer, in which the lattice constant does not decrease, is large, the contraction of the crystal lattice of the second electrolyte layer is suppressed, so the average lattice constant of the entire second electrolyte layer does not decrease, or even increases. (3) Electrolytes that have a lattice constant that is not small, or even large, compared to the lattice constant of a powdered perovskite-type proton-conducting oxide of the same composition in a wet state can improve the power generation performance of a proton-conducting ceramic cell. These findings led to the completion of the present invention.

[0014] In other words, the present invention (1) is an electrolyte layer for a proton-conducting ceramic cell, The following general formula (1): A1 x1 B1 y1 O 3+z1 (1) (In formula (1), A1 is at least one of Ca, Sr, and Ba, B1 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, x1 is 0.08 to 1.20, y1 is 0.08 to 1.20, z1 is -0.80 to +0.80, and the proportion of Ce in B1 is 30 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by , The average lattice constant of the electrolyte layer for the proton-conducting ceramic cell in the wet state from the 0% position to the X% position in the thickness direction from the air electrode side is A. X When B is the wetted lattice constant of a powdered perovskite-type proton-conducting oxide having the same composition as the electrolyte layer for the proton-conducting ceramic cell at the 50% thickness position from the air electrode side, then (A) is the ratio of B to B. X -B) ratio (((A X The value of -B) / B)×100) is between -0.05% and +0.15% for X=50 to 90. This invention provides an electrolyte layer for proton-conducting ceramic cells characterized by the following features.

[0015] Furthermore, the present invention (2) provides the electrolyte layer for a proton-conducting ceramic cell according to (1), characterized in that the content of Ce in the total B1 elements is 30 mol% or more.

[0016] Furthermore, the present invention (3) provides an electrolyte layer for a proton-conducting ceramic cell according to (1) or (2), characterized in that the content of Zr in the total A1 elements is 5 mol% or more.

[0017] Furthermore, the present invention (4) provides an electrolyte layer for a proton-conducting ceramic cell according to any of (1) to (3), characterized in that the thickness of the electrolyte layer for the proton-conducting ceramic cell is 1 to 100 μm.

[0018] Furthermore, the present invention (5) provides an electrolyte for a proton-conducting ceramic cell, characterized in that the single-layer electrolyte layer for the proton-conducting ceramic cell is any of the proton-conducting ceramic cell electrolytes described in (1) to (4).

[0019] Furthermore, the present invention (6) is a two-layer electrolyte for a proton-conducting ceramic cell, comprising a first electrolyte layer formed on the air electrode side and a second electrolyte layer formed on the fuel electrode side. The first electrolyte layer is an electrolyte layer for a proton-conducting ceramic cell, as described in (1) to (4). The second electrolyte layer is defined by the following general formula (2): A2 x2 B2 y2 O 3+z2 (2) (In formula (2), A2 is at least one of Ca, Sr, and Ba; B2 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x2 is 0.08 to 1.20; y2 is 0.08 to 1.20; z2 is -0.80 to +0.80; and the proportion of Zr in B2 is 45 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by , The ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or greater. This invention provides an electrolyte for proton-conducting ceramic cells characterized by the following features.

[0020] Furthermore, the present invention (7) provides an electrolyte for a proton-conducting ceramic cell according to (6), characterized in that the first electrolyte layer on the side of the second electrolyte layer has a continuous Zr change section in which the Zr concentration increases toward the second electrolyte layer, and the second electrolyte layer on the side of the first electrolyte layer has a continuous Ce change section in which the Ce concentration increases toward the first electrolyte layer.

[0021] Furthermore, the present invention (8) comprises at least a fuel electrode, an electrolyte formed on the surface of the fuel electrode, and an air electrode. The electrolyte is the electrolyte for proton-conducting ceramic cells of (6) or (7), The fuel electrode contains 30.0% by mass or more of a fuel electrode oxide containing Ni. This invention provides a proton-conducting ceramic cell characterized by the following features.

[0022] Furthermore, the present invention (9) provides a proton-conducting ceramic cell according to (8), characterized in that the Ni-containing oxide for the fuel electrode is NiO.

[0023] Furthermore, the present invention (10) further includes an intermediate layer between the air electrode and the electrolyte, The intermediate layer is given by the following general formula (4): A4 x4 B4 y4 O 3+z4 (4) (In formula (4), A4 is at least one of Ca, Sr, Ba, and La; B4 is at least one of Sc, Ga, Y, Zr, In, Ce, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Hf; x4 is between 0.80 and 1.20; y4 is between 0.80 and 1.20; and z4 is between -0.80 and +0.80.) It contains 80.0% by mass or more of a perovskite-type proton-conducting oxide represented by [formula]. The present invention provides a proton-conducting ceramic cell characterized by (8) or (9).

[0024] Furthermore, the present invention (11) relates to a fuel electrode material layer containing a Ni-containing fuel electrode oxide or the following general formula (5) formed on the surface of the calcined layer of the fuel electrode material layer: A5 x5 B5 y5 O 3+z5 (5) (In formula (5), A5 is at least one of Ca, Sr, and Ba; B5 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x5 is 0.08 to 1.20; y5 is 0.08 to 1.20; z5 is -0.80 to +0.80; and the proportion of Zr in B5 is 45 mol% or more.) A material layer for the second electrolyte layer consisting of a perovskite-type proton-conducting oxide represented by the following formula (6): or a calcined layer of the material layer for the second electrolyte layer at 900 to 1300°C, and the following general formula (6): A6 x6 B6 y6 O 3+z6 (6) (In formula (6), A6 is at least one of Ca, Sr, and Ba; B6 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x6 is 0.08 to 1.20; y6 is 0.08 to 1.20; z6 is -0.80 to +0.80; and the proportion of Ce in B6 is 30 mol% or more.) The present invention provides a method for manufacturing a proton-conducting ceramic cell, characterized by having a step of forming a fuel electrode and electrolyte laminate, wherein the fuel electrode and the electrolyte formed on the surface of the fuel electrode are produced by firing a laminate of firing raw materials, which consists of a material layer for the first electrolyte layer made of a perovskite-type proton-conducting oxide represented by [formula], or a calcined layer of the material layer for the first electrolyte layer at 900 to 1300°C, with a thickness such that the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer after firing (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or more, and firing the laminate of firing raw materials, which consists of the material layer for the second electrolyte layer or a calcined layer of the material layer for the second electrolyte layer, at 1200 to 1500°C.

[0025] In this specification, when a numerical range is indicated using "~", it includes the numbers at both ends of the range. In other words, "○○~△△" means "greater than or equal to ○○ and less than or equal to △△". [Effects of the Invention]

[0026] According to the present invention, it is possible to provide an electrolyte for proton-conducting ceramic cells that can improve the power generation performance of the proton-conducting ceramic cells. Furthermore, according to the present invention, it is possible to provide an electrolyte for an electrolysis apparatus that can improve the electrolysis performance of the electrolysis apparatus. [Brief explanation of the drawing]

[0027] [Figure 1] This is a schematic end view of a proton-conducting ceramic cell having an example of the morphology of the electrolyte layer for the proton-conducting ceramic cell of the present invention. [Figure 2] This is a schematic end view of a proton-conducting ceramic cell having another embodiment of the electrolyte layer for the proton-conducting ceramic cell of the present invention. [Figure 3] This is a schematic end view illustrating a method for measuring the average lattice constant AX and lattice constant B of the electrolyte layer for a proton-conducting ceramic cell, and shows an enlarged view of a portion of the electrolyte layer. [Figure 4] This shows the compositional analysis results of the cross-section in the thickness direction of the electrolyte layer in Example 1. [Figure 5] This shows the compositional analysis results of the cross-section in the thickness direction of the electrolyte layer in Example 2. [Figure 6] This graph shows the grid constants at each measurement position in Example 1. [Figure 7] This graph shows the grid constants at each measurement position in Example 2. [Figure 8] This graph shows the evaluation results of the output characteristics of Example 1, Example 2, and Comparative Example 1. [Modes for carrying out the invention]

[0028] The electrolyte layer for proton-conducting ceramic cells of the present invention is This is an electrolyte layer for proton-conducting ceramic cells. The following general formula (1): A1 x1 B1 y1 O 3+z1 (1) (In formula (1), A1 is at least one of Ca, Sr, and Ba, B1 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, x1 is 0.08 to 1.20, y1 is 0.08 to 1.20, z1 is -0.80 to +0.80, and the proportion of Ce in B1 is 30 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by , The average lattice constant of the electrolyte layer for the proton-conducting ceramic cell in the wet state from the 0% position to the X% position in the thickness direction from the air electrode side is A. X When B is the wetted lattice constant of a powdered perovskite-type proton-conducting oxide having the same composition as the electrolyte layer for the proton-conducting ceramic cell at the 50% thickness position from the air electrode side, then (A) is the ratio of B to B. X -B) ratio (((A X The value of -B) / B)×100) is between -0.05% and +0.15% for X=50 to 90. This is an electrolyte layer for proton-conducting ceramic cells characterized by the following features.

[0029] Figure 1 is a schematic end view of a proton-conducting ceramic cell having an example of the morphology of the electrolyte layer for the proton-conducting ceramic cell of the present invention. The proton-conducting ceramic cell 1 comprises a fuel electrode 2 for the proton-conducting ceramic cell, a two-layer electrolyte 3 for the proton-conducting ceramic cell formed on the surface of the fuel electrode 2 and consisting of a first electrolyte layer 5a formed in layers on the air electrode 4 side and a second electrolyte layer 5b formed in layers on the fuel electrode 2 side, and an air electrode 4 for the proton-conducting ceramic cell formed on the surface of the electrolyte 3. In the proton-conducting ceramic cell 1, the first electrolyte layer 5a formed on the air electrode 4 side of the two-layer electrolyte 3 for the proton-conducting ceramic cell is the electrolyte layer for the proton-conducting ceramic cell of the present invention.

[0030] Figure 2 is a schematic end view of another embodiment of a proton-conducting ceramic cell having an example of the morphology of the electrolyte layer for the proton-conducting ceramic cell of the present invention. The proton-conducting ceramic cell 11 comprises a fuel electrode 12 for the proton-conducting ceramic cell, a single-layer electrolyte 13 for the proton-conducting ceramic cell formed on the surface of the fuel electrode 12, and an air electrode 14 for the proton-conducting ceramic cell formed on the surface of the electrolyte 13. In the proton-conducting ceramic cell 11, the electrolyte 13 for the proton-conducting ceramic cell is the electrolyte layer for the proton-conducting ceramic cell of the present invention; that is, the electrolyte 13 for the proton-conducting ceramic cell is formed solely of the electrolyte layer for the proton-conducting ceramic cell of the present invention.

[0031] Furthermore, the proton-conducting ceramic cell may have an intermediate layer between the electrolyte and the air electrode for purposes such as preventing gas leakage, suppressing electron leakage, reducing the reaction resistance of the air electrode, and improving the adhesion strength of the interface.

[0032] The electrolyte layer for the proton-conducting ceramic cell of the present invention is defined by the following general formula (1): A1 x1 B1 y1 O 3+z1 (1) (In formula (1), A1 is at least one of Ca, Sr, and Ba, B1 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, x1 is 0.08 to 1.20, y1 is 0.08 to 1.20, z1 is -0.80 to +0.80, and the proportion of Ce in B1 is 30 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by [formula].

[0033] In general formula (1), A1 is at least one of Ca, Sr, and Ba, preferably at least one of Sr and Ba, and more preferably Ba. B1 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, preferably at least one of Fe, Co, Ni, Zr, Ce, Sc, Y, In, and Yb, and more preferably at least one of Zr, Ce, Y, and Yb. x1 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. y1 is 0.08 to 1.20, preferably 0.09 to 1.10, and more preferably 0.95 to 1.05. z1 is between -0.80 and +0.80, preferably between -0.06 and +0.06, and more preferably between -0.04 and +0.04. If A1 consists of two or more elements, the value of x1 is the sum of those two or more elements, and if B1 consists of two or more elements, the value of y1 is the sum of those two or more elements.

[0034] In the perovskite-type proton-conducting oxide represented by general formula (1), the proportion of Ce in B1 is 30 mol% or more, preferably 35 to 90 mol%, and more preferably 40 to 85 mol%. By having the proportion of Ce in B1 within the above range, the lattice constant of the electrolyte layer for the proton-conducting ceramic cell of the present invention can be increased.

[0035] In the perovskite-type proton-conducting oxide represented by general formula (1), the proportion of Ba in A1 is preferably 50 mol% or more, more preferably 80 to 100 mol%, and more preferably 90 to 100 mol%. By having the proportion of Ba in A1 within the above range, the proton conductivity of the proton-conducting ceramic cell can be increased.

[0036] The electrolyte layer for a proton-conducting ceramic cell of the present invention forms part or all of the electrolyte of the proton-conducting ceramic cell. An air electrode is formed on one side of the electrolyte layer for a proton-conducting ceramic cell of the present invention. In other words, the electrolyte layer for a proton-conducting ceramic cell of the present invention is a layered electrolyte layer for a proton-conducting ceramic cell formed on the air electrode side in a proton-conducting ceramic cell having a two-layer structure electrolyte, or a layered electrolyte layer for a proton-conducting ceramic cell that forms the electrolyte in a proton-conducting ceramic cell having a single-layer structure electrolyte.

[0037] In the electrolyte layer for the proton-conducting ceramic cell of the present invention, in thin-film X-ray measurement, the average lattice constant in the wet state from the 0% position to the X% position in the thickness direction from the air electrode side of the electrolyte layer for the proton-conducting ceramic cell of the present invention is A X When B is the wetted lattice constant of a powdered perovskite-type proton-conducting oxide having the same composition as the electrolyte for a proton-conducting ceramic cell at the 50% thickness position from the air electrode side, then (A) is the value of B. X -B) ratio (((A X -B) / B)×100) is -0.05% to +0.15% for X=50 to 90. The relationship between "lattice constant B" and "average lattice constant A" is as follows: X The power generation performance of the proton-conducting ceramic cell is enhanced when the ratio of the "difference" is within the above range in the thickness direction from 50% to 90% from the air electrode side. X The lattice constant B is a value obtained by measuring a half-cell consisting of a fuel electrode for a proton-conducting ceramic cell and an electrolyte for a proton-conducting ceramic cell formed on the surface of the fuel electrode, using thin-film X-ray diffraction.

[0038] In the present invention, the average lattice constant A of the electrolyte layer for proton-conducting ceramic cells in the wet state from the 0% position to the X% position in the thickness direction from the air electrode side. XThis is determined by thin-film X-ray measurement. Figure 3 shows the average lattice constant A of the electrolyte layer 33 for the proton-conducting ceramic cell. X This is a schematic end view illustrating the method for measuring the lattice constant B, and is an enlarged view of a part of the electrolyte layer. The electrolyte layer 33 for the proton-conducting ceramic cell in Figure 3 corresponds to the first electrolyte layer 5a in Figure 1 and the electrolyte layer 13 for the proton-conducting ceramic cell in Figure 2. In Figure 3, the position of reference numeral 32 is the position from (0%) to X% of the surface 31 (0%) on the air electrode side of the electrolyte layer 33 for the proton-conducting ceramic cell. Then, in an X-ray diffractometer, the inside of the apparatus is set to an atmospheric environment, specifically a temperature of 25°C ± 5°C and a relative humidity of 40% ± 20%, and X-rays 34 are irradiated onto the surface 31 (on the air electrode side) of the electrolyte layer 33 for the proton-conducting ceramic cell at an angle ω. The diffracted X-rays are measured, and then the lattice constant in the wet state is determined by analysis using the Reedbelt method. In thin-film X-ray measurement, the wavelength and irradiation angle ω of the X-ray 34 are adjusted so that diffracted X-rays can be measured from the surface (0% from the surface) to the position where the X-ray penetration depth is 90% in the thickness direction. Reference numeral 35 indicates the surface or interface of the electrolyte layer 33 opposite to the air electrode side. Next, the average lattice constant A is obtained from the resulting diffracted X-rays. X The lattice constant is calculated as follows: In thin-film X-ray measurement, when X-rays are allowed to penetrate to a position where the X-ray penetration depth is X% in the thickness direction, the diffraction X-ray data is obtained as the average value of the diffraction X-ray data from the 0% position to the X% position in the thickness direction from the air electrode side. Therefore, the lattice constant calculated from the diffraction X-ray data at the X% position in the thickness direction from the air electrode side is the average value from the 0% position to the X% position in the thickness direction from the air electrode side. This average value is the average lattice constant A in the wet state from the 0% position to the X% position in the thickness direction from the air electrode side. X For example, when X-rays are allowed to penetrate to a position where the X-ray penetration depth is 50% in the thickness direction, the diffraction X-ray data is obtained as the average value of the diffraction X-ray data from the 0% position to the 50% position in the thickness direction from the air electrode side. Therefore, the lattice constant calculated from the diffraction X-ray data at the 50% position in the thickness direction from the air electrode side is the average value from the 0% position to the 50% position in the thickness direction from the air electrode side. This average value is the average lattice constant A in the wet state from the 0% position to the 50% position.50 Similarly, when X-rays are allowed to penetrate to a position where the X-ray penetration depth is 90% in the thickness direction, the diffraction X-ray data is obtained as the average value of the diffraction X-ray data from the 0% position to the 90% position in the thickness direction from the air electrode side. Therefore, the lattice constant calculated from the diffraction X-ray data at the 90% position in the thickness direction from the air electrode side is the average value from the 0% position to the 90% position in the thickness direction from the air electrode side. This average value is the average lattice constant A in the wet state from the 0% position to the 90% position. 90 In this invention, the average lattice constant A is determined at least at two locations, preferably near the 50% and 90% positions, and preferably at a total of three or more locations, including those near the 50% and 90% positions, plus at intervals of 1-20%. X Calculate.

[0039] Furthermore, in this invention, the lattice constant B in the wet state of a powdered perovskite-type proton-conducting oxide having the same composition as the composition at the 50% position in the thickness direction from the air electrode side of the electrolyte layer for the proton-conducting ceramic cell is determined by powder X-ray diffraction analysis. First, a cross-section of the electrolyte for the proton-conducting ceramic cell is processed by focused ion beam (FIB) processing to perform compositional analysis of the cross-section cut in the thickness direction of the electrolyte layer. Then, the composition at the 50% position in the thickness direction from the air electrode side of the electrolyte layer is determined. Next, a powder of perovskite-type proton-conducting oxide having the same composition as the obtained composition is prepared, and the obtained perovskite-type proton-conducting oxide powder is subjected to X-ray diffraction analysis in an X-ray diffractometer with the temperature inside the apparatus set to 25°C ± 5°C and the relative humidity to 40% ± 20%. Then, the lattice constant B, which is the lattice constant in the wet state, is calculated from the obtained diffracted X-rays.

[0040] In the present invention, the composition of the electrolyte layer for a proton-conducting ceramic cell at the 50% position in the thickness direction from the air electrode side is determined by elemental analysis of the cross-section of the electrolyte layer using an electron beam microprobe analyzer (EPMA).

[0041] Next, in the range from 50% to 90% in the thickness direction from the air electrode side (where X = 50 to 90), the average lattice constant A X For each position found, (A) x -B) ratio (((A x Calculate -B) / B)×100).

[0042] Furthermore, in the electrolyte layer for the proton-conducting ceramic cell of the present invention, in the range from 50% to 90% in the thickness direction from the air electrode side (at X=50~90), the lattice constant B is (average lattice constant A X -Lattice constant B) ratio (((A X -B) / B)×100) is -0.05% to +0.15%, preferably -0.01% to +0.12%, and more preferably +0.00% to +0.10%. In other words, (A) is the value of B at each position determined in the range from 50% to 90% in the thickness direction from the air electrode side. x -B) ratio (((A x -B) / B)×100) is all -0.05% to +0.15%, preferably -0.01% to +0.12%, and more preferably +0.00% to +0.10%. (Average lattice constant A) with respect to lattice constant B in the electrolyte layer for the proton-conducting ceramic cell of the present invention. X - When the proportion of lattice constant B) is within the above range, the amount of protons moving within the electrolyte layer increases, thus improving the power generation performance of the proton-conducting ceramic cell.

[0043] The thickness of the electrolyte layer for the proton-conducting ceramic cell of the present invention is 1.0 to 100 μm, preferably 1.5 to 30 μm, and more preferably 2.0 to 10 μm. By having the electrolyte layer thickness within the above range, the electrolyte resistance can be reduced.

[0044] The first embodiment of the present invention is a proton-conducting ceramic cell electrolyte, characterized in that the proton-conducting ceramic cell electrolyte is a single-layer structured proton-conducting ceramic cell electrolyte, and the proton-conducting ceramic cell electrolyte is the proton-conducting ceramic cell electrolyte layer of the present invention.

[0045] The first embodiment of the present invention is a single-layer electrolyte for a proton-conducting ceramic cell, comprising only the electrolyte layer of the present invention. The first embodiment of the present invention is used as an electrolyte in a proton-conducting ceramic cell having at least a fuel electrode, an electrolyte, and an air electrode.

[0046] The thickness of the electrolyte for the proton-conducting ceramic cell in the first embodiment of the present invention, that is, the thickness of the electrolyte layer for the proton-conducting ceramic cell in the present invention, is 1 to 100 μm, preferably 1.5 to 30 μm, and more preferably 2.0 to 10 μm. By having the thickness of the electrolyte for the proton-conducting ceramic cell in the first embodiment of the present invention within the above range, the electrolyte resistance can be reduced.

[0047] The electrolyte for a proton-conducting ceramic cell according to the second embodiment of the present invention is a two-layer electrolyte for a proton-conducting ceramic cell, comprising a first electrolyte layer formed on the air electrode side and a second electrolyte layer formed on the fuel electrode side. The first electrolyte layer is the electrolyte layer for the proton-conducting ceramic cell of the present invention. The second electrolyte layer is defined by the following general formula (2): A2 x2 B2 y2 O 3+z2 (2) (In formula (2), A2 is at least one of Ca, Sr, and Ba; B2 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x2 is 0.08 to 1.20; y2 is 0.08 to 1.20; z2 is -0.80 to +0.80; and the proportion of Zr in B2 is 45 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by , The ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or greater. This is an electrolyte for proton-conducting ceramic cells characterized by the following features.

[0048] The second embodiment of the present invention is a two-layer electrolyte for a proton-conducting ceramic cell, comprising a first electrolyte layer formed on the air electrode side and a second electrolyte layer formed on the fuel electrode side, wherein the first electrolyte layer is the electrolyte layer for a proton-conducting ceramic cell according to the present invention. The second embodiment of the present invention is used as an electrolyte in a proton-conducting ceramic cell having at least a fuel electrode, an electrolyte, and an air electrode.

[0049] The second electrolyte layer of the electrolyte for a proton-conducting ceramic cell in the second embodiment of the present invention is given by the following general formula (2): A2 x2 B2 y2 O 3+z2 (2) (In formula (2), A2 is at least one of Ca, Sr, and Ba; B2 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x2 is 0.08 to 1.20; y2 is 0.08 to 1.20; z2 is -0.80 to +0.80; and the proportion of Zr in B2 is 45 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by [formula].

[0050] In general formula (2), A2 is at least one of Ca, Sr, and Ba, preferably at least one of Sr and Ba, and more preferably Ba. B2 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, preferably at least one of Fe, Co, Ni, Zr, Ce, Sc, Y, In, and Yb, and more preferably at least one of Zr, Ce, Y, and Yb. x2 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. y2 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. z2 is between -0.80 and +0.80, preferably between -0.06 and +0.06, and more preferably between -0.04 and +0.04. Furthermore, if A2 consists of two or more elements, the value of x2 is the sum of those two or more elements, and if B2 consists of two or more elements, the value of y2 is the sum of those two or more elements.

[0051] In the perovskite-type proton-conducting oxide represented by general formula (2), the proportion of Zr in B2 is 45 mol% or more, preferably 60 to 90 mol%, and more preferably 70 to 85 mol%. By having the proportion of Zr in B2 within the above range, the diffusion of Ni from the fuel electrode to the first electrolyte layer can be suppressed.

[0052] In the perovskite-type proton-conducting oxide represented by general formula (2), the proportion of Ba in A2 is preferably 50 mol% or more, more preferably 80 to 100 mol%, and more preferably 90 to 100 mol%. By having the proportion of Ba in A2 within the above range, the proton conductivity of the proton-conducting ceramic cell can be increased.

[0053] In the second embodiment of the electrolyte for a proton-conducting ceramic cell of the present invention, a first electrolyte layer made of the electrolyte layer for a proton-conducting ceramic cell of the present invention is formed on the air electrode side, and a second electrolyte layer made of a perovskite-type proton-conducting oxide represented by general formula (2) is formed on the fuel electrode side. Perovskite-type composite oxides, where the B-site element is mainly Ce, are composite oxides that can increase the lattice constant of the electrolyte layer formed using Ce because of its large ionic radius. However, during the calcination process for producing electrolytes made from perovskite-type composite oxides where the B-site element is mainly Ce, the Ce in the composite oxide is replaced by Ni, which has a small ionic radius, due to diffusion from the fuel electrode, resulting in a decrease in the lattice constant of the electrolyte. Therefore, in the electrolyte for a proton-conducting ceramic cell of the second embodiment of the present invention, a second electrolyte layer made of a perovskite-type proton-conducting oxide represented by general formula (2), in which the B-site element is mainly Zr, is placed between the first electrolyte layer, which is made of a perovskite-type proton-conducting oxide represented by general formula (1), in which the B-site element is mainly Ce, and the fuel electrode. This prevents the diffusion of Ni from the fuel electrode to the first electrolyte layer, thereby preventing the lattice constant of the electrolyte from becoming smaller. As a result, the amount of protons in the electrolyte layer increases, the proton conductivity increases, and the power generation performance of the proton-conducting ceramic cell improves.

[0054] In the electrolyte for a proton-conducting ceramic cell according to the second embodiment of the present invention, the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or more, preferably 3.0 to 10.0, and more preferably 5.0 to 10.0. Because the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is within the above range, that is, because the first electrolyte layer is 2.0 times or more, preferably 3.0 to 10.0 times, and more preferably 5.0 to 10.0 times thicker than the second electrolyte layer, even if Ni with a small ionic radius diffuses from the fuel electrode into the second electrolyte layer and Zr in the composite oxide is replaced by Ni, the thick first electrolyte prevents the crystal lattice from shrinking, thus preventing the lattice constant of the second electrolyte layer from decreasing. As a result, the amount of protons moving within the electrolyte layer increases, the proton conductivity increases, and the power generation performance of the proton-conducting ceramic cell improves.

[0055] In the second embodiment of the electrolyte for a proton-conducting ceramic cell of the present invention, it is preferable that the first electrolyte layer on the second electrolyte layer side has a continuous Zr change region where the Zr concentration increases toward the second electrolyte layer, and that the second electrolyte layer on the first electrolyte layer side has a continuous Ce change region where the Ce concentration increases toward the first electrolyte layer, in order to increase the adhesion strength of the bonding interface between the first electrolyte layer and the second electrolyte layer. In the present invention, the fact that the first electrolyte layer on the second electrolyte layer side has a continuous Zr change region where the Zr concentration increases toward the second electrolyte layer, and that the second electrolyte layer on the first electrolyte layer side has a continuous Ce change region where the Ce concentration increases toward the first electrolyte layer, can be confirmed by elemental analysis of the cross-section of the electrolyte layer using EPMA.

[0056] The thickness of the electrolyte for the proton-conducting ceramic cell in the second embodiment of the present invention is preferably 1.0 to 100 μm, more preferably 1.5 to 30 μm, and more preferably 2.0 to 10 μm. By having the thickness of the electrolyte for the proton-conducting ceramic cell in the second embodiment of the present invention within the above range, the electrolyte resistance can be reduced.

[0057] The proton-conducting ceramic cell of the present invention comprises at least a fuel electrode, an electrolyte formed on the surface of the fuel electrode, and an air electrode. The electrolyte is the electrolyte for a proton-conducting ceramic cell according to the first embodiment of the present invention or the electrolyte for a proton-conducting ceramic cell according to the second embodiment of the present invention. The fuel electrode contains 30.0% by mass or more of a fuel electrode oxide containing Ni. This is a proton-conducting ceramic cell characterized by [specific feature].

[0058] The proton-conducting ceramic cell of the present invention comprises at least a fuel electrode, an electrolyte formed on the surface of the fuel electrode, and an air electrode.

[0059] The fuel electrode of the proton-conducting ceramic cell of the present invention mainly consists of a fuel electrode oxide containing Ni. Examples of fuel electrode oxides containing Ni include NiO, NiFeOx, NiCoOx, NiFeCoOx, etc., with NiO being preferred.

[0060] Examples of fuel electrodes include those formed from fuel electrode oxides, and those formed from fuel electrode oxides and proton-conducting oxides. Within limits that do not impair the effects of the present invention, in addition to fuel electrode oxides, electron-conducting oxides, proton-conducting oxides, oxide ion-conducting oxides, alumina for adjusting the coefficient of thermal expansion, etc., may also be included.

[0061] The perovskite-type fuel electrode oxide used in the fuel electrode may be a single type or a combination of two or more types. When a proton-conducting oxide is used in the fuel electrode, the proton-conducting oxide may be a single type or a combination of two or more types.

[0062] The content of Ni-containing fuel electrode oxides in the fuel electrode is 30.0% by mass or more, preferably 40% by mass or more, more preferably 60% by mass or more, and particularly preferably 100.0% by mass.

[0063] In the fuel electrode, the mass ratio of fuel electrode oxide to proton-conducting oxide (fuel electrode oxide:proton-conducting oxide) is preferably 100:0 to 30:70, more preferably 80:20 to 40:60, and more preferably 70:30 to 50:50. By having the mass ratio of fuel electrode oxide to proton-conducting oxide in the fuel electrode within the above range, the electrode resistance can be low and the power density can be high.

[0064] The fuel electrode is preferably porous. The porosity of the fuel electrode is preferably 30.0 to 50.0 volume%, more preferably 35.0 to 45.0 volume%. Because the porosity of the fuel electrode is within the above range, the gas diffusion resistance, which is part of the electrode resistance, is reduced, resulting in lower electrode resistance and higher current density.

[0065] In this invention, the porosity of the fuel electrode is determined by separating the fuel electrode material and the voids by binarization in a cross-sectional image of the fuel electrode obtained by scanning electron microscopy (SEM). In this invention, the same applies to the air electrode and the intermediate layer in determining the porosity.

[0066] The film thickness of the fuel electrode is preferably 100 to 700 μm, more preferably 200 to 600 μm. Because the fuel electrode film thickness is within this range, the gas diffusion resistance, which is part of the electrode resistance, is reduced, resulting in lower electrode resistance and higher current density.

[0067] The electrolyte in the proton-conducting ceramic cell of the present invention is the electrolyte for the proton-conducting ceramic cell of the first embodiment of the present invention or the electrolyte for the proton-conducting ceramic cell of the second embodiment of the present invention. Therefore, the proton-conducting ceramic cell of the present invention has an electrolyte layer for the proton-conducting ceramic cell of the present invention. In the proton-conducting ceramic cell of the present invention, the electrolyte is formed on the surface of the fuel electrode.

[0068] The air electrode of the proton-conducting ceramic cell of the present invention mainly consists of an electronically conductive oxide for the air electrode of the proton-conducting ceramic cell. The electronically conductive oxide for the air electrode used in the air electrode may be one type or a combination of two or more types. Furthermore, the air electrode may contain electronically conductive oxides other than the electronically conductive oxide for the air electrode, proton-conducting oxides, oxide ion-conducting oxides, alumina, etc., for adjusting the coefficient of thermal expansion, to the extent that the effects of the present invention are not impaired.

[0069] The content of the electronically conductive oxide for the air electrode in the air electrode is 30.0% by mass or more, preferably 40.0% by mass or more, more preferably 50.0% by mass or more, and particularly preferably 60.0% by mass. By having the content of the electronically conductive oxide for the air electrode in the air electrode within the above range, the air electrode resistance can be low and the power density can be high.

[0070] In the air electrode, the mass ratio of the electronically conductive oxide for the air electrode to the proton-conducting oxide (electronically conductive oxide for the air electrode: proton-conducting 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 electronically conductive oxide for the air electrode to the proton-conducting oxide in the air electrode is within the above range, the contact points between the electronically conductive oxide for the air electrode and the proton-conducting oxide increase, expanding the reaction field, lowering electrode resistance, and increasing current density.

[0071] The electron-conducting oxide for the air electrode is not particularly limited, but for example, the following general formula (3): A3 (1-x3) B3 x3 C3 y3 O 3-z3 (3) A perovskite-type oxide material represented by is preferred.

[0072] In general formula (3), A3 is one or more of Y, La, Ce, Pr, Sm, and Gd, preferably one or more of La, Sm, and Gd. B3 is one or more of Sr, Ca, and Ba, preferably Sr. C3 is one or more of Cr, Mn, Fe, Co, Ni, and Cu, preferably one or more of Mn, Fe, and Co. x3 is 0.20 to 0.60, preferably 0.25 to 0.50, and particularly preferably 0.30 to 0.50. y3 is 0.95 to 1.15, preferably 1.00 to 1.10, and particularly preferably 1.00 to 1.05. z3 is -1.00 to 1.00, preferably -0.50 to 0.50, and particularly preferably -0.30 to 0.30.

[0073] Examples of electron-conducting oxides for air electrodes include (LaBa)MnO3, (LaBa)FeO3, (LaBa)CoO3, and (LaBa)(CoFe)O3.

[0074] The air electrode is preferably porous. The porosity of the air electrode is 10.0 to 80.0 volume%, preferably 30.0 to 60.0 volume%, and more preferably 40.0 to 50.0 volume%. Having the porosity of the air electrode within this range increases the contact area with the electrolyte and the reaction field within the air electrode, resulting in lower electrode resistance and higher current density.

[0075] The thickness of the air electrode is preferably 5.0 to 50.0 μm, more preferably 10.0 to 20.0 μm. Because the thickness of the air electrode is within this range, the gas diffusion resistance, which is part of the electrode resistance, is reduced, resulting in lower electrode resistance and higher current density.

[0076] The proton-conducting ceramic cell of the present invention may have an intermediate layer between the air electrode and the electrolyte. The intermediate layer is provided for various purposes. Examples of intermediate layers include an intermediate layer for preventing gas leakage, an intermediate layer for suppressing electron leakage, an intermediate layer for reducing the reaction resistance of the air electrode, and an intermediate layer for improving the adhesion strength of the interface.

[0077] The intermediate layer of the proton-conducting ceramic cell of the present invention is mainly the following general formula (4): A4 x4 B4 y4 O 3+z4 (4) (In formula (4), A4 is at least one of Ca, Sr, Ba, and La; B4 is at least one of Sc, Ga, Y, Zr, In, Ce, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Hf; x4 is between 0.80 and 1.20; y4 is between 0.80 and 1.20; and z4 is between -0.80 and +0.80.) It consists of a perovskite-type proton-conducting oxide represented by [formula].

[0078] In general formula (4), A4 is at least one of Ca, Sr, Ba, and La, and is preferably Ba. B4 is at least one of Sc, Ga, Y, Zr, In, Ce, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Hf, preferably at least one of Y, Zr, Ce, and Yb. x4 is 0.80 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. y4 is 0.80 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. z4 is between -0.80 and +0.80, preferably between -0.40 and +0.40, and more preferably between -0.20 and +0.00. If A4 consists of two or more elements, the value of x4 is the sum of the values ​​of those two or more elements. If B4 consists of two or more elements, the value of y4 is the sum of the values ​​of those two or more elements.

[0079] As a perovskite-type proton-conducting oxide represented by general formula (4), see formula (4a): Ba 0.80 ~ 1.20 Ce 0.10 ~ 0.80 Zr 0.10 ~ 0.80 Y 0.00 ~ 0.20 Yb 0.00 ~ 0.20 O 2.20 ~ 3.80 (4a) A perovskite-type proton-conducting oxide represented by [formula] is preferred.

[0080] The perovskite-type proton-conducting oxide represented by general formula (4) may be a single type or a combination of two or more types, as long as it satisfies general formula (4).

[0081] The intermediate layer contains 80.0% by mass or more of a perovskite-type proton-conducting oxide represented by general formula (4), and may be either a dense or porous material, preferably with a porosity of 30.0 to 100.0% by volume.

[0082] The intermediate layer is mainly composed of a perovskite-type proton-conductive oxide represented by general formula (4). Since the intermediate layer is mainly composed of the perovskite-type proton-conductive oxide represented by general formula (4), the intermediate layer has high proton conductivity and high chemical stability, so that output density and durability can be improved.

[0083] The intermediate layer may contain proton-conductive oxides other than the perovskite-type proton-conductive oxide represented by general formula (4), electron-conductive oxides, oxide ion-conductive oxides, and alumina or the like for adjusting the coefficient of thermal expansion, as long as the effects of the present invention are not impaired.

[0084] In the intermediate layer, the content of the perovskite-type proton-conductive oxide represented by general formula (4) is 80.0% by mass or more, preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and particularly preferably 100.0% by mass. When the content of the perovskite-type proton-conductive oxide represented by general formula (4) in the intermediate layer falls within the above range, cathode resistance can be lowered and output density can be increased.

[0085] The intermediate layer may be either a dense body or a porous body. The porosity of the intermediate layer is 10.0 to 70.0% by volume, preferably 20.0 to 60.0% by volume. When the porosity of the intermediate layer falls within the above range, the resistance of the intermediate layer can be reduced.

[0086] The film thickness of the intermediate layer is preferably 1.0 to 20.0 µm, more preferably 1.0 to 10.0 µm. When the film thickness of the intermediate layer falls within the above range, the resistance of the intermediate layer can be reduced.

[0087] The method for producing a proton conductive ceramic cell of the present invention is characterized in that the following general formula (5) is formed on the surface of a fuel electrode material layer containing a Ni-containing fuel electrode oxide or a fired layer of said fuel electrode material layer: A5 x5 B5 y5 O 3+z5 (5) (In formula (5), A5 is at least one of Ca, Sr, and Ba; B5 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x5 is 0.08 to 1.20; y5 is 0.08 to 1.20; z5 is -0.80 to +0.80; and the proportion of Zr in B5 is 45 mol% or more.) A material layer for the second electrolyte layer consisting of a perovskite-type proton-conducting oxide represented by the following formula (6): or a calcined layer of the material layer for the second electrolyte layer at 900 to 1300°C, and the following general formula (6): A6 x6 B6 y6 O 3+z6 (6) (In formula (6), A6 is at least one of Ca, Sr, and Ba; B6 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x6 is 0.08 to 1.20; y6 is 0.08 to 1.20; z6 is -0.80 to +0.80; and the proportion of Ce in B6 is 30 mol% or more.) This is a method for manufacturing a proton-conducting ceramic cell, characterized by having a step of forming a fuel electrode and electrolyte laminate, wherein the fuel electrode and the electrolyte formed on the surface of the fuel electrode are produced by firing a laminate of firing raw materials, which consists of a material layer for the first electrolyte layer made of a perovskite-type proton-conducting oxide represented by [formula], or a calcined layer of the material layer for the first electrolyte layer fired at 900 to 1300°C, with a thickness such that the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer after firing (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or more, and firing the first electrolyte layer material layer or the calcined layer of the material layer for the second electrolyte layer at 1200 to 1500°C.

[0088] The calcined raw material laminate according to the method for manufacturing a proton-conducting ceramic cell of the present invention comprises a fuel electrode material layer or a calcined layer of a fuel electrode material layer containing a Ni-containing fuel electrode oxide, a second electrolyte layer material layer or a calcined layer of a second electrolyte layer formed on the surface of the fuel electrode material layer or the calcined layer of the fuel electrode material layer, and a first electrolyte layer material layer or a calcined layer of a first electrolyte layer formed on the surface of the first electrolyte layer material layer or the calcined layer of the first electrolyte layer.

[0089] The fuel electrode material layer contains a fuel electrode material oxide containing Ni. Examples of fuel electrode material oxides containing Ni include NiO, NiFeOx, NiCoOx, and NiFeCoOx, with NiO being preferred.

[0090] Examples of fuel electrode material layers include those formed from fuel electrode oxides, and those formed from fuel electrode oxides and proton-conducting oxides. The fuel electrode material layer may also contain, to the extent that it does not impair the effects of the present invention, electron-conducting oxides, proton-conducting oxides, oxide ion-conducting oxides, alumina for adjusting the coefficient of thermal expansion, etc., in addition to fuel electrode oxides.

[0091] The perovskite-type fuel electrode oxide used in the fuel electrode material layer may be a single type or a combination of two or more types. When a proton-conducting oxide is used in the fuel electrode, the proton-conducting oxide may be a single type or a combination of two or more types.

[0092] The content of Ni-containing fuel electrode oxides in the fuel electrode material layer is 30.0% by mass or more, preferably 40% by mass or more, more preferably 60% by mass or more, and particularly preferably 100.0% by mass.

[0093] In the fuel electrode material layer, the mass ratio of the fuel electrode oxide to the proton-conducting oxide (fuel electrode oxide : proton-conducting oxide) is preferably 100:0 to 30:70, more preferably 80:20 to 40:60, and still more preferably 70:30 to 50:50. When the mass ratio of the fuel electrode oxide to the proton-conducting oxide in the fuel electrode material layer falls within the above range, electrode resistance can be reduced and output density can be increased.

[0094] In the production of a calcined raw material laminate, a fuel electrode material layer formed into a layer shape may be used as it is without being pre-calcined, or alternatively, the fuel electrode material layer may be pre-calcined at 900 to 1300°C, preferably 1000 to 1250°C, and used as a pre-calcined fuel electrode material layer.

[0095] The material layer for the second electrolyte layer is represented by the following general formula (5): A₅ x5 B₅ y5 O 3+z5 (5) (In formula (5), A₅ is at least one selected from the group consisting of Ca, Sr and Ba; B₅ is at least one selected from the group consisting of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb and Lu; x₅ is 0.08 to 1.20; y₅ is 0.08 to 1.20; z₅ is -0.80 to +0.80; and the proportion of Zr in B₅ is 45 mol% or more.) comprises a perovskite-type proton-conducting oxide represented by the above formula.

[0096] In general formula (5), A₅ is at least one selected from the group consisting of Ca, Sr and Ba, preferably at least one selected from the group consisting of Sr and Ba, and more preferably Ba. B₅ is at least one selected from the group consisting of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb and Lu, preferably at least one selected from the group consisting of Fe, Co, Ni, Zr, Ce, Sc, Y, In and Yb, and more preferably at least one selected from the group consisting of Zr, Ce, Y and Yb. x5 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. y5 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. z5 is between -0.80 and +0.80, preferably between -0.06 and +0.06, and more preferably between -0.04 and +0.04. Furthermore, if A5 consists of two or more elements, the value of x5 is the sum of those two or more elements, and if B5 consists of two or more elements, the value of y5 is the sum of those two or more elements.

[0097] In the perovskite-type proton-conducting oxide represented by general formula (5), the proportion of Zr in B5 is 45 mol% or more, preferably 60 to 90 mol%, and more preferably 70 to 85 mol%. By having the proportion of Zr in B5 within the above range, an electrolyte layer for proton-conducting ceramic cells with a large lattice constant can be obtained.

[0098] In the perovskite-type proton-conducting oxide represented by general formula (5), the proportion of Ba in A5 is preferably 50 mol% or more, more preferably 80 to 100 mol%, and more preferably 90 to 100 mol%. By having the proportion of Ba in A5 within the above range, a proton-conducting ceramic cell with high proton conductivity can be obtained.

[0099] In the preparation of the calcined raw material laminate, the material layer for the second electrolyte layer, which is formed into layers, may be used as is without calcination, or it may be used as a calcined layer of the material layer for the second electrolyte layer, which has been calcined at 900 to 1300°C, preferably 1000 to 1250°C.

[0100] The material layer for the first electrolyte layer is given by the following general formula (6): A6 x6 B6 y6 O 3+z6 (6) (In formula (6), A6 is at least one of Ca, Sr, and Ba; B6 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x6 is 0.08 to 1.20; y6 is 0.08 to 1.20; z6 is -0.80 to +0.80; and the proportion of Ce in B6 is 30 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by [formula].

[0101] In general formula (6), A6 is at least one of Ca, Sr, and Ba, preferably at least one of Sr and Ba, and more preferably Ba. B6 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, preferably at least one of Fe, Co, Ni, Zr, Ce, Sc, Y, In, and Yb, and more preferably at least one of Zr, Ce, Y, and Yb. x6 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. y6 is 0.08 to 1.20, preferably 0.90 to 1.10, and more preferably 0.95 to 1.05. z6 is between -0.80 and +0.80, preferably between -0.06 and +0.06, and more preferably between -0.04 and +0.04. Furthermore, if A6 consists of two or more elements, the value of x6 is the sum of those two or more elements, and if B6 consists of two or more elements, the value of y6 is the sum of those two or more elements.

[0102] In the perovskite-type proton-conducting oxide represented by general formula (6), the proportion of Ce in B6 is 30 mol% or more, preferably 35 to 90 mol%, and more preferably 40 to 85 mol%. By having the proportion of Ce in B6 within the above range, an electrolyte layer for proton-conducting ceramic cells with a large lattice constant can be obtained.

[0103] In the perovskite-type proton-conducting oxide represented by general formula (6), the proportion of Ba in A6 is preferably 50 mol% or more, more preferably 80 to 100 mol%, and more preferably 90 to 100 mol%. By having the proportion of Ba in A6 within the above range, a proton-conducting ceramic cell with high proton conductivity can be obtained.

[0104] In the preparation of the calcined raw material laminate, the first electrolyte layer material layer, which has been formed into a layered shape, may be used as is without calcination, or it may be used as a calcined layer of the first electrolyte layer material layer, which has been calcined at 900 to 1300°C, preferably 1000 to 1250°C.

[0105] In the method for manufacturing a proton-conducting ceramic cell of the present invention, by arranging a second electrolyte layer material layer or a calcined layer of the second electrolyte layer material layer between the first electrolyte layer material layer or the calcined layer of the first electrolyte layer material layer and the fuel electrode material layer, the second electrolyte layer material layer or the calcined layer of the second electrolyte layer material layer can prevent the diffusion of Ni from the fuel electrode material layer to the first electrolyte layer, thereby preventing a decrease in the lattice constant of the electrolyte. As a result, the amount of protons moving within the electrolyte layer increases, the proton conductivity increases, and the power generation performance of the proton-conducting ceramic cell improves.

[0106] In the production of a calcined raw material laminate, a calcined raw material laminate is obtained by laminating a material layer for the second electrolyte layer or a calcined layer of the material layer for the second electrolyte layer with a material layer for the first electrolyte layer or a calcined layer of the material layer for the first electrolyte layer. At this time, the thickness of the calcined layer of the material layer for the second electrolyte layer and the material layer for the first electrolyte layer are adjusted so that the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer after calcination (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or more, preferably 2.5 to 10.0, and more preferably 3.0 to 10.0, and these are then laminated to produce a calcined raw material laminate. By adjusting the thickness of the material layer for the second electrolyte layer or the calcined layer of the material layer for the second electrolyte layer, and the material layer for the first electrolyte layer or the calcined layer of the material layer for the first electrolyte layer, so that the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer after calcination is within the above range, even if Ni with a small ionic radius diffuses from the fuel electrode into the second electrolyte layer and Zr in the composite oxide is replaced by Ni, the thick first electrolyte prevents the crystal lattice from shrinking, thus preventing the lattice constant of the second electrolyte layer from decreasing. As a result, the amount of protons moving within the electrolyte layer increases, the proton conductivity increases, and the power generation performance of the proton-conducting ceramic cell improves.

[0107] In the method for producing a proton-conducting ceramic cell of the present invention, the method for producing the laminate of fired raw materials is not particularly limited. For example, a slurry for the fuel electrode is prepared by mixing a dispersion medium with fuel electrode material and, if necessary, additives such as binders, plasticizers, and dispersants. This slurry is then formed into a sheet by microgravure printing, tape casting, extrusion molding, etc., to produce a green sheet for the fuel electrode material layer. Alternatively, a slurry for the material layer of the second electrolyte layer is prepared by mixing a dispersion medium with a perovskite-type proton-conducting oxide represented by general formula (5) and, if necessary, additives such as binders, plasticizers, and dispersants. This slurry is then formed into a sheet by microgravure printing, tape casting, extrusion molding, etc., to produce a green sheet for the material layer of the second electrolyte layer. Next, a green sheet for the second electrolyte layer material layer is laminated onto a green sheet for the fuel electrode material layer, hot-pressed, and then calcined at a predetermined temperature to obtain a laminate of the calcined fuel electrode material layer and the calcined second electrolyte layer material layer. Next, a dispersion medium, a perovskite-type proton-conducting oxide represented by general formula (6), and additives such as binders, plasticizers, and dispersants as needed are mixed to prepare a slurry for the material layer of the first electrolyte layer. Then, the slurry for the material layer of the first electrolyte layer is applied to a laminate of the calcined layer of the fuel electrode material layer and the calcined layer of the material layer of the second electrolyte layer by spin coating or ultrasonic spraying to obtain a calcined raw material laminate.

[0108] In the process of forming the fuel electrode and electrolyte laminate, the calcined raw material laminate is calcined at 1200-1500°C to produce the fuel electrode and the electrolyte formed on the surface of the fuel electrode.

[0109] In the process of forming a laminate of fuel electrode and electrolyte, the firing temperature of the fired raw material laminate is 1200 to 1500°C, preferably 1300 to 1450°C, and more preferably 1350 to 1430°C.

[0110] In the present invention's method for manufacturing a proton-conducting ceramic cell, after performing a step to form a laminate of a fuel electrode and an electrolyte, an air electrode or an intermediate layer and an air electrode are formed on the surface of the electrolyte of the fuel electrode and electrolyte laminate to manufacture a proton-conducting ceramic cell.

[0111] The air electrode or intermediate layer is formed by preparing a slurry in which at least powdered air electrode material or powdered intermediate layer material is dispersed, then applying the slurry to the object to be formed to form a slurry coating film and shaping it into layers, then drying it to produce an air electrode material layer or intermediate layer material layer, and then firing it at a firing temperature, for example, 700 to 1400°C to sinter it.

[0112] The proton-conducting ceramic cell of the present invention may be formed on a support. The support is preferably porous in order to achieve good gas diffusion. The porosity of the porous support is, for example, 10 to 60 volume percent. The shape of the porous support can be a flat plate or a tube, but is not particularly limited. Examples of support materials include oxides such as alumina or zirconia, or heat-resistant metals.

[0113] The proton-conducting ceramic cell of the present invention may have a porous layer on the electrode (air electrode or fuel electrode) having a higher porosity than the electrode. The porosity of the porous layer is higher than that of the electrode, preferably 25.0 to 55.0 volume%. As the material of the porous layer, there are perovskite-type oxide materials, such as (LaBa)MnO3, (LaBa)FeO3, (LaBa)CoO3, (LaBa)(CoFe)O3, etc. The La in the above electronically conductive material can be substituted or partially substituted with other lanthanides (Pr, Sm, Gd), and the Ba can be substituted or partially substituted with other alkaline earth metals (Ca, Sr). In addition, metallic materials (Ti, Mn, Fe, Co, Ni, Cu, etc.) can be used as the material of the porous layer. The metallic materials include those reduced by gases such as hydrogen, carbon monoxide, hydrocarbons, and biofuels. For example, if NiO (oxide) is used as a material during manufacturing, when the ceramic cell is constructed and operated by the aforementioned gas, the NiO is reduced to Ni (metal).

[0114] The proton-conducting ceramic cell of the present invention and the proton-conducting ceramic cell obtained by the method for manufacturing the proton-conducting ceramic cell of the present invention are suitable for use as cells in a proton-conducting ceramic fuel cell because, when used as cells in a proton-conducting ceramic fuel cell, the amount of protons moving within the electrolyte layer increases. In other words, the proton-conducting ceramic fuel cell of the present invention is characterized by having the proton-conducting ceramic cell of the present invention or the proton-conducting ceramic cell obtained by the method for manufacturing the proton-conducting ceramic cell of the present invention. Furthermore, because the amount of protons moving within the electrolyte layer increases, the proton-conducting ceramic fuel cell of the present invention has high power generation performance.

[0115] Furthermore, some electrolysis apparatuses use proton-conducting ceramic cells as their cells. The proton-conducting ceramic cell of the present invention and the proton-conducting ceramic cell obtained by the method for manufacturing the proton-conducting ceramic cell of the present invention are suitable for use as cells in electrolysis apparatuses because they increase the amount of protons moving within the electrolyte layer when used as cells in electrolysis apparatuses. In other words, the electrolysis apparatus of the present invention is characterized by having the proton-conducting ceramic cell of the present invention or the proton-conducting ceramic cell obtained by the method for manufacturing the proton-conducting ceramic cell of the present invention. The electrolysis apparatus of the present invention has high electrolysis performance because it increases the amount of protons moving within the electrolyte layer. [Examples]

[0116] Next, the present invention will be described in more detail with reference to examples, but these are merely illustrative and not intended to limit the present invention. <Synthesis of oxide powder materials by spray pyrolysis method> Spray pyrolysis is one method for synthesizing nano-sized oxide powder materials. While it can synthesize single oxide powder materials, it can also synthesize oxide powder materials composed of two or more oxides. In this case, a good dispersion state can be obtained for the two or more oxides in the composite. Another feature is the ability to control the primary particle size over a wide range. The following describes the synthesis of oxide powder materials by spray pyrolysis in the examples provided.

[0117] The spray pyrolysis method involves preparing an aqueous spray solution containing a metal salt of an electron-conducting material source for the air electrode and a metal salt of a proton-conducting material source, atomizing the aqueous spray solution by ultrasonic vibration, and then introducing the atomized aqueous spray solution into a heating furnace to obtain an oxide powder material for the air electrode.

[0118] By appropriately selecting the concentration ratio of each metal element contained in the aqueous solution for spraying, the composition ratio of various metal elements constituting the primary particles of the electron-conducting material and the primary particles of the proton-conducting material for the air electrode was adjusted.

[0119] The aqueous solution for spraying in the spraying device was atomized by ultrasonic vibration (1.75 MHz), and then the atomized aqueous solution for spraying was introduced into a heating furnace through piping connected to the spraying device by flowing with air as a carrier gas. The metal salts of the electron-conducting material source and the metal salts of the proton-conducting material source for the air electrode in the aqueous solution for spraying were thermally decomposed and oxidized to obtain oxide powder material for the air electrode. A four-stage electric furnace was used as the heating furnace (furnace temperatures were 300, 500, 700, and 900°C from the first stage, and furnace heating times were 8 seconds, 8 seconds, 8 seconds, and 8 seconds from the first stage). <Preparation of aqueous solution for spraying> (1) Aqueous solution for spraying s1 6.96 g of lanthanum nitrate hexahydrate, 8.87 g of barium nitrate, 7.80 g of cobalt nitrate hexahydrate, 5.58 g of zirconium oxide nitrate dihydrate, and 1.04 g of ytterbium nitrate pentahydrate were weighed and dissolved in pure water. Then, pure water was added to make a total volume of 1000 ml to prepare an aqueous solution for spraying, s1. By spray thermal decomposition of the aqueous solution for spraying, 50 parts by mass of 0.05 mol per liter of La was obtained. 0.6 Ba 0.4 CoO3 (hereinafter referred to as LBC) - 50 parts by mass BaZr 0.9 Yb 0.1 O3 (hereinafter referred to as BZYb10) can be synthesized.

[0120] <Preparation of Nitrate-Containing Electrode Material Precursors> (1) Nitrate-containing electrode material precursor p1 Using the aforementioned spray aqueous solution s1, spray pyrolysis was performed by an ultrasonic spray pyrolysis method to obtain a nitrate-containing electrode material precursor p1 of LBC-BZYb10.

[0121] X-ray diffraction analysis of the nitrate-containing electrode material precursor of LBC-BZYb10 revealed diffraction peaks identifiable as LBC and BZYb, confirming that it is a powder material containing crystalline LBC and BZYb10. In addition, a diffraction peak identifiable as barium nitrate was also observed, confirming that it contains not only crystalline oxides but also nitrates.

[0122] <BaZr 0.8 Yb 0.2 O3(BZYb20)> Manufactured by Sakai Chemical Industry Co., Ltd.

[0123] <BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O3(BCZYYb4411)> Manufactured by Kusaka Rare Metals Research Institute

[0124] <BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O3(BCZYYb7111)> DOWA Electronics

[0125] (Example 1) <Preparation of green sheets for fuel electrode material layers> NiO (Sumitomo Metal Mining, IP grade) and BaZr 0.8 Yb 0.2 O3 (BZYb2O) and carbon were mixed in a mass ratio of 6:4:1, and a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant were added. Ball mill mixing was performed for 48 hours to obtain a slurry for the fuel electrode. A green sheet for the fuel electrode material layer was obtained by microgravure printing of this slurry. The thickness of the green sheet for the fuel electrode material layer was adjusted by laminating the sheets to a thickness of approximately 800 μm and then hot pressing.

[0126] <Preparation of green sheets for the material layer of the second electrolyte layer> BaZr 0.8 Yb 0.2 O3 (hereinafter referred to as BZYb20), a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant were added, and the mixture was ball-milled for 48 hours to obtain a slurry for the material layer of the second electrolyte layer. A green sheet for the material layer of the second electrolyte layer was obtained by microgravure printing of this slurry. The green sheet for the material layer of the second electrolyte layer was adjusted to have an average film thickness of 3 μm.

[0127] <Fabrication of a laminate consisting of a calcined layer for the fuel electrode material and a calcined layer for the second electrolyte material> A green sheet for the fuel electrode material layer was laminated onto a green sheet for the second electrolyte layer material layer, hot-pressed, and then calcined at 1200°C for 1 hour to obtain a laminate of the calcined fuel electrode material layer and the calcined second electrolyte layer material layer. <Preparation of calcined raw material laminates> BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3-A slurry for the first electrolyte layer material layer was obtained by adding δ (hereinafter referred to as BCZYYb4411), a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant, and then mixing with a ball mill for 48 hours. Next, a laminate of calcined raw materials was obtained by spin-coating a slurry for the material layer of the first electrolyte layer onto a laminate of the calcined layer of the fuel electrode material layer and the calcined layer of the material layer for the second electrolyte layer to a thickness of 8 μm.

[0128] <Firing> The calcined raw material laminate was calcined at 1430°C for 3 hours to obtain a laminate of fuel electrode and electrolyte.

[0129] <Fabrication of the air electrode> Ethyl cellulose, a plasticizer, a dispersant, and α-terpineol were added to the above-mentioned nitrate-containing electrode material precursor p1, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain the air electrode slurry c1. Next, the air electrode slurry c1 was applied to the electrolyte surface of the fuel electrode and electrolyte laminate to a diameter of φ6 mm using a screen printing method with a 5 μm mesh. After drying at 150°C for 30 minutes, it was subjected to cold isotropic pressurization (CIP) at 300 MPa to obtain a pre-pressurized electrode material coating. Subsequently, the air electrode was fabricated by firing at 900°C for 1 hour, and a proton-conducting ceramic cell was obtained. The obtained proton-conducting ceramic cell had a fuel electrode thickness of approximately 600 μm, an average thickness of the first electrolyte layer of 6 μm, an average thickness of the second electrolyte layer of 2 μm, and an air electrode thickness of approximately 10 μm. At this time, the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer was 3.0.

[0130] (Example 2) <Preparation of green sheets for fuel electrode material layers> NiO (Sumitomo Metal Mining, IP grade) and BaZr 0.8 Yb 0.2O3 (BZYb2O) and carbon were mixed in a mass ratio of 6:4:1, and a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant were added. Ball mill mixing was performed for 48 hours to obtain a slurry for the fuel electrode. A green sheet for the fuel electrode material layer was obtained by microgravure printing of this slurry. The thickness of the green sheet for the fuel electrode material layer was adjusted by laminating the sheets to a thickness of approximately 800 μm and then hot pressing.

[0131] <Preparation of green sheets for the material layer of the second electrolyte layer> BaZr 0.8 Yb 0.2 O3 (hereinafter referred to as BZYb20), a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant were added, and the mixture was ball-milled for 48 hours to obtain a slurry for the material layer of the second electrolyte layer. A green sheet for the material layer of the second electrolyte layer was obtained by microgravure printing of this slurry. The green sheet for the material layer of the second electrolyte layer was adjusted to have an average film thickness of 3 μm.

[0132] <Fabrication of a laminate consisting of a calcined layer for the fuel electrode material and a calcined layer for the second electrolyte material> A green sheet for the fuel electrode material layer was laminated onto a green sheet for the second electrolyte layer material layer, hot-pressed, and then calcined at 1200°C for 1 hour to obtain a laminate of the calcined fuel electrode material layer and the calcined second electrolyte layer material layer. <Preparation of calcined raw material laminates> BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3- A slurry for the first electrolyte layer material layer was obtained by adding δ (hereinafter referred to as BCZYYb7111), a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant, and then mixing with a ball mill for 48 hours. Next, a laminate of calcined raw materials was obtained by spin-coating a slurry for the material layer of the first electrolyte layer onto a laminate of the calcined layer of the fuel electrode material layer and the calcined layer of the material layer for the second electrolyte layer to a thickness of 8 μm.

[0133] <Firing> The calcined raw material laminate was calcined at 1430°C for 3 hours to obtain a laminate of fuel electrode and electrolyte.

[0134] <Fabrication of the air electrode> Ethyl cellulose, a plasticizer, a dispersant, and α-terpineol were added to the above-mentioned nitrate-containing electrode material precursor p1, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain the air electrode slurry c1. Next, the air electrode slurry c1 was applied to the electrolyte surface of the fuel electrode and electrolyte laminate to a diameter of φ6 mm using a screen printing method with a 5 μm mesh. After drying at 150°C for 30 minutes, it was subjected to cold isotropic pressurization (CIP) at 300 MPa to obtain a pre-pressurized electrode material coating. Subsequently, the air electrode was fabricated by firing at 900°C for 1 hour, and a proton-conducting ceramic cell was obtained. The obtained proton-conducting ceramic cell had a fuel electrode thickness of approximately 600 μm, an average thickness of the first electrolyte layer of 6 μm, an average thickness of the second electrolyte layer of 2 μm, and an air electrode thickness of approximately 10 μm. At this time, the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer was 3.0.

[0135] <Measurement of the average lattice constant A of electrolytes using thin-film X-ray measurement> As measurement samples, thin-film X-ray measurements were performed on the fuel electrode and electrolyte laminates of Example 1 and Example 2 using an X-ray diffractometer (device name X'Pert Pro MPD, manufactured by Spectris). The measurement conditions were as follows: the temperature inside the X-ray diffractometer was set to 25°C ± 5°C and the relative humidity to 40% ± 20%. A copper tube X-ray source (X-ray wavelength: Kα1 = 1.540593 Å, Kα2 = 1.544427 Å) was used, a parabolic multilayer mirror was used in the incident optical system, and a parallel beam optical system equipped with a 0.09 mm collimator, graphite monochromator, and proportional counter was used in the receiving optical system. The X-ray incident angle ω on the electrolyte surface was set to 0.25 to 19°, and the diffracted X-rays were measured. The obtained measurement results were analyzed using the Reedbelt method, and the average lattice constant A in the wet state at each measurement position (penetration depth position of each X-ray) from the 50% to 90% position in the thickness direction was determined. X The following was determined. The results are shown in Figure 6 (Example 1) and Figure 7 (Example 2). In addition, the lattice constant (lattice constant B) of the wet state of a powdered perovskite-type proton-conducting oxide with the same composition as the composition at the 50% position in the thickness direction is shown in Figures 6 and 7.

[0136] <Elemental analysis of the cross-section in the thickness direction of the electrolyte> As measurement samples, elemental analysis of the cross-section in the thickness direction of the electrolyte was performed on the fuel electrode and electrolyte laminates of Example 1 and Example 2 using energy-dispersive X-ray spectroscopy (instrument name: EPMA8050G, Shimadzu Corporation). The results are shown in Figure 4 (Example 1) and Figure 5 (Example 2). As a result, the composition at the 50% position in the thickness direction was, in Example 1, BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3- δ, Example 2 is BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3- It was δ. Further, it was confirmed that in both Example 1 and Example 2, near the boundary between the first electrolyte layer and the second electrolyte layer, a Zr continuous change portion where the Zr concentration increases toward the second electrolyte layer is formed in the first electrolyte layer on the second electrolyte layer side, and a Ce continuous change portion where the Ce concentration increases toward the first electrolyte layer is formed in the second electrolyte layer on the first electrolyte layer side.

[0137] <Measurement of Lattice Constant B by X-ray Measurement Method> BaCe having the same composition as the composition at the 50% position in the thickness direction analyzed above 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3- δ and BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3- δ powdered perovskite-type proton conductive oxides were produced. Subsequently, X-ray measurement was performed on the powdered perovskite-type proton conductive oxide using an X-ray diffractometer (device name: X'Pert Pro MPD, manufactured by Spectris Co., Ltd.). As measurement conditions, the temperature inside the X-ray diffractometer was set to 25°C ± 5°C, and the relative humidity was set to 40% ± 20%, a copper tube target (X-ray wavelength: Kα1 = 1.540593Å, Kα2 = 1.544427Å) was used as the X-ray source, and diffracted X-rays were measured. The obtained measurement results were analyzed by the Rietveld method, and the lattice constant B in a wet state of the powdered perovskite-type proton conductive oxide having the same composition as that at the 50% position in the thickness direction was calculated. The result was 4.312Å for Example 1 and 4.377Å for Example 2.

[0138] Subsequently, for Example 1 and Example 2, (average lattice constant A X - lattice constant B) ratio (((A X - B) / B) × 100) was calculated with respect to the lattice constant B at each measurement position. As a result, in Example 1, from the 50% position (X-ray penetration depth: 3 μm) to the 90% position (X-ray penetration depth: 5.4 μm), ((A XThe value of -B) / B)×100 was also in the range of -0.05% to +0.15%. Furthermore, in Example 2, from the 50% position (X-ray penetration depth 3 μm) to the 90% position (X-ray penetration depth 5.4 μm), the measurement position ((A X The value of -B) / B)×100 was also in the range of -0.05% to +0.15%.

[0139] (Comparative Example 1) <Preparation of the green sheet for the fuel electrode material layer in Comparative Example 1> NiO (Sumitomo Metal Mining, IP grade) and BaZr 0.8 Yb 0.2 O3 (BZYb2O) and carbon were mixed in a mass ratio of 6:4:1, and a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant were added. Ball mill mixing was performed for 48 hours to obtain a slurry for the fuel electrode. A green sheet for the fuel electrode material layer was obtained by microgravure printing of this slurry. The thickness of the green sheet for the fuel electrode material layer was adjusted by laminating the sheets to a thickness of approximately 800 μm and then hot pressing.

[0140] <Preparation of the green sheet for the electrolyte layer material layer in Comparative Example 1> BaZr 0.8 Yb 0.2 O3 (hereinafter referred to as BZYb20), a toluene-based solvent (Fujifilm Wako Pure Chemical Industries, 204-01861), a binder, a plasticizer, and a dispersant were added, and the mixture was ball-milled for 48 hours to obtain a slurry for the material layer of the second electrolyte layer. The slurry for the material layer of the electrolyte layer of Comparative Example 1 was applied by spin coating to obtain a calcined raw material laminate.

[0141] <Firing> The calcined raw material laminate was calcined at 1430°C for 3 hours to obtain a laminate of fuel electrode and electrolyte.

[0142] <Fabrication of the air electrode> Ethyl cellulose, a plasticizer, a dispersant, and α-terpineol were added to the above-mentioned nitrate-containing electrode material precursor p1, and the mixture was kneaded in a kneader at room temperature for 1 minute and 30 seconds to obtain the air electrode slurry c1. Next, the air electrode slurry c1 was applied to the electrolyte surface of the fuel electrode and electrolyte laminate to a diameter of φ6 mm using a screen printing method with a 5 μm mesh. After drying at 150°C for 30 minutes, it was subjected to cold isotropic pressurization (CIP) at 300 MPa to obtain a pre-pressurized electrode material coating. Subsequently, the air electrode was fabricated by firing at 900°C for 1 hour, and a proton-conducting ceramic cell was obtained. The thickness of the fuel electrode in the obtained proton-conducting ceramic cell was approximately 600 μm, the thickness of the electrolyte layer in Comparative Example 1 was 5 μm, and the thickness of the air electrode was 10 μm.

[0143] <Measurement of the average lattice constant A of electrolytes using thin-film X-ray measurement> As a measurement sample, thin-film X-ray measurements were performed on the fuel electrode and electrolyte laminate of Comparative Example 1 using an X-ray diffractometer (instrument name X'Pert Pro MPD, manufactured by Spectris). The measurement conditions were as follows: the temperature inside the X-ray diffractometer was set to 25°C ± 5°C and the relative humidity to 40% ± 20%. A copper tube X-ray source (X-ray wavelength: Kα1 = 1.540593 Å, Kα2 = 1.544427 Å) was used, a parabolic multilayer mirror was used in the incident optical system, and a parallel beam optical system equipped with a 0.09 mm collimator, graphite monochromator, and proportional counter was used in the receiving optical system. The X-ray incident angle ω on the electrolyte surface was set to 0.25 to 19°, and the diffracted X-rays were measured. The obtained measurement results were analyzed using the Leadbelt method, and the average lattice constant A in the wet state at each measurement position from 50% to 90% in the thickness direction was determined. X They sought it.

[0144] <Elemental analysis of the cross-section in the thickness direction of the electrolyte> As a sample for measurement, the fuel electrode and electrolyte laminate of Comparative Example 1 was subjected to elemental analysis of the cross-section in the thickness direction of the electrolyte using energy-dispersive X-ray spectroscopy (instrument name: EPMA8050G, manufactured by Shimadzu Corporation). As a result, the composition at the 50% position in the thickness direction is BaZr0.8 Yb 0.2 O 3- δ.

[0145] <Measurement of lattice constant B by X-ray measurement method> A powdery perovskite-type proton-conducting oxide of BaZr 0.8 Yb 0.2 O 3- δ having the same composition as the composition at the 50% position in the thickness direction analyzed above was produced. Subsequently, X-ray measurement was performed on the powdery perovskite-type proton-conducting oxide using an X-ray diffractometer (device name: X'Pert Pro MPD, manufactured by Spectris Co., Ltd.). As measurement conditions, the temperature inside the X-ray diffractometer was set to 25°C ± 5°C and the relative humidity was set to 40% ± 20%, a copper tube bulb (X-ray wavelengths: Kα1 = 1.540593Å, Kα2 = 1.544427Å) was used as the X-ray source, and diffracted X-rays were measured. The obtained measurement results were analyzed by the Rietveld method, and the lattice constant B in a wet state of the powdery perovskite-type proton-conducting oxide having the same composition as that at the 50% position in the thickness direction was calculated, and was found to be 4.231Å.

[0146] Next, the ratio of (average lattice constant A X - lattice constant B) to lattice constant B at each position in the thickness direction (((A X - B) / B)×100) was calculated. As a result, it was found that in Comparative Example 1, from the 50% position (X-ray penetration depth: 3 μm) to the 90% position (X-ray penetration depth: 5.4 μm), there are positions where the value of ((A X - B) / B)×100 deviates from the range of -0.05% to +0.15%.

[0147] <Performance evaluation of proton-conducting ceramic cell> For the proton-conducting ceramic cells of Example 1, Example 2, and Comparative Example 1, current-voltage characteristics were measured at 600°C using an electrochemical measurement system (potentiostat / galvanostat, VSP, Biologic Inc.) by supplying hydrogen humidified at 25°C to the fuel electrode and air humidified at 25°C to the air electrode. The maximum power density was determined from the results of the current-voltage characteristics measurement. The results are shown in Figure 8. The maximum power densities of Example 1 and Example 2 increased by approximately 1.6 times and approximately 1.9 times, respectively, compared to that of Comparative Example 1. In Figure 8, □ and ■ represent Example 1, × represents Example 2, and ○ and ● represent Comparative Example 1. [Explanation of Symbols]

[0148] 1, 11 Proton-conducting ceramic cells 2, 12 Fuel electrode 3, 13 Electrolytes 4, 14 Air poles 5a First electrolyte layer 5b Second electrolyte layer 31 Surface of the air electrode side of the electrolyte layer 33 for proton-conducting ceramic cell 32 X% position from the air electrode side surface 31 of the electrolyte layer 33 for proton-conducting ceramic cell 33. Electrolyte layer for proton-conducting ceramic cells 34 X-ray 35. The surface or interface of the electrolyte layer opposite to the air electrode side. ω X-ray incidence angle [Industrial applicability]

[0149] By using the present invention, it is possible to manufacture proton-conducting ceramic cells with high power generation performance due to their low air electrode resistance.

Claims

1. This is an electrolyte layer for proton-conducting ceramic cells. The following general formula (1): A1 x1 B1 y1 O 3+z1 (1) (In formula (1), A1 is at least one of Ca, Sr, and Ba, B1 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu, x1 is 0.08 to 1.20, y1 is 0.08 to 1.20, z1 is -0.80 to +0.80, and the proportion of Ce in B1 is 30 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by , The average lattice constant of the electrolyte layer for the proton-conducting ceramic cell in the wet state from the 0% position to the X% position in the thickness direction from the air electrode side is A. X When B is the wet lattice constant of a powdered perovskite-type proton-conducting oxide having the same composition as the electrolyte layer for the proton-conducting ceramic cell at a position 50% in the thickness direction from the air electrode side, then (A) is the value relative to B. X -B) ratio (((A X The value of -B) / B)×100) is between -0.05% and +0.15% for X = 50 to 90. An electrolyte layer for proton-conducting ceramic cells characterized by the following.

2. The electrolyte layer for a proton-conducting ceramic cell according to claim 1, characterized in that the content of Ce in the total B1 elements is 30 mol% or more.

3. The electrolyte layer for a proton-conducting ceramic cell according to claim 1, characterized in that the content of Zr in the total B1 elements is 5 mol% or more.

4. The electrolyte layer for a proton-conducting ceramic cell according to claim 1, characterized in that the thickness of the electrolyte layer for the proton-conducting ceramic cell is 1 to 100 μm.

5. An electrolyte for a proton-conducting ceramic cell, characterized in that the electrolyte layer for the proton-conducting ceramic cell is the electrolyte for the proton-conducting ceramic cell described in claim 1.

6. This is a two-layer electrolyte for a proton-conducting ceramic cell, consisting of a first electrolyte layer formed on the air electrode side and a second electrolyte layer formed on the fuel electrode side. The first electrolyte layer is the electrolyte layer for a proton-conducting ceramic cell according to claim 1, The second electrolyte layer is defined by the following general formula (2): A2 x2 B2 y2 O 3+z2 (2) (In formula (2), A2 is at least one of Ca, Sr, and Ba; B2 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x2 is 0.08 to 1.20; y2 is 0.08 to 1.20; z2 is -0.80 to +0.80; and the proportion of Zr in B2 is 45 mol% or more.) It consists of a perovskite-type proton-conducting oxide represented by , The ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or more. An electrolyte for proton-conducting ceramic cells characterized by the following.

7. The electrolyte for a proton-conducting ceramic cell according to claim 6, characterized in that the first electrolyte layer on the side of the second electrolyte layer has a continuous Zr change portion in which the Zr concentration increases toward the second electrolyte layer, and the second electrolyte layer on the side of the first electrolyte layer has a continuous Ce change portion in which the Ce concentration increases toward the first electrolyte layer.

8. It comprises at least a fuel electrode, an electrolyte formed on the surface of the fuel electrode, and an air electrode, The electrolyte is the electrolyte for a proton-conducting ceramic cell according to claim 6, The fuel electrode contains 30.0% by mass or more of a fuel electrode oxide containing Ni. A proton-conducting ceramic cell characterized by [feature].

9. The proton-conducting ceramic cell according to claim 8, characterized in that the Ni-containing oxide for the fuel electrode is NiO.

10. An intermediate layer is further provided between the air electrode and the electrolyte. The intermediate layer is given by the following general formula (4): A4 x4 B4 y4 O 3+z4 (4) (In formula (4), A4 is at least one of Ca, Sr, Ba, and La; B4 is at least one of Sc, Ga, Y, Zr, In, Ce, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Hf; x4 is between 0.80 and 1.20; y4 is between 0.80 and 1.20; and z4 is between -0.80 and +0.80.) It contains 80.0% by mass or more of a perovskite-type proton-conducting oxide represented by [formula]. A proton-conducting ceramic cell according to claim 8, characterized by the above.

11. The following general formula (5) is formed on the surface of a fuel electrode material layer containing a Ni-containing fuel electrode oxide or the calcined layer of said fuel electrode material layer: A5 x5 B5 y5 O 3+z5 (5) (In formula (5), A5 is at least one of Ca, Sr, and Ba; B5 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x5 is 0.08 to 1.20; y5 is 0.08 to 1.20; z5 is -0.80 to +0.80; and the proportion of Zr in B5 is 45 mol% or more.) A material layer for the second electrolyte layer made of a perovskite-type proton-conducting oxide represented by the following formula (6): or a calcined layer of the material layer for the second electrolyte layer at 900 to 1300°C, and the following general formula (6): A6 x6 B6 y6 O 3+z6 (6) (In formula (6), A6 is at least one of Ca, Sr, and Ba; B6 is at least one of Fe, Co, Ni, Zr, Ce, Hf, Sc, Ga, Y, In, Gd, Dy, Ho, Tm, Er, Yb, and Lu; x6 is 0.08 to 1.20; y6 is 0.08 to 1.20; z6 is -0.80 to +0.80; and the proportion of Ce in B6 is 30 mol% or more.) A method for manufacturing a proton-conducting ceramic cell, comprising a fuel electrode and electrolyte laminate formation step, wherein the laminate consists of a material layer for the first electrolyte layer made of a perovskite-type proton-conducting oxide represented by [formula], or a calcined layer of the material layer for the first electrolyte layer at 900 to 1300°C, wherein the ratio of the thickness of the first electrolyte layer to the thickness of the second electrolyte layer after calcination (thickness of the first electrolyte layer / thickness of the second electrolyte layer) is 2.0 or more, and the calcined raw material laminate is formed by calcining the first electrolyte layer material layer or the calcined layer of the material layer for the first electrolyte layer at 1200 to 1500°C to produce a laminate of a fuel electrode and an electrolyte formed on the surface of the fuel electrode.

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