Electrochemical single cell, inter-connector joint, cell stack, hot module, and gas production device

Abstract

To inhibit occurrence of cracks in a fuel electrode properly during operation of a cell stack.SOLUTION: A solid oxide electrochemical single cell includes: a solid electrolyte layer 12; an air electrode 14 which is laminated on the front surface side of the solid electrolyte layer; a fuel electrode 16 laminated on the rear surface side of the solid electrolyte layer; and a reinforcement part 20 laminated on at least a part of an outer periphery part of a rear surface, which is opposite to the solid electrolyte layer side, of the fuel electrode. A thermal expansion coefficient of the reinforcement part 20 is smaller than a thermal expansion coefficient of the fuel electrode 16.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a solid oxide electrochemical unit cell, an interconnector assembly, a cell stack, a hot module, and a gas production device. [Background technology]

[0002] Solid oxide electrochemical cells, which use solid oxide as an electrolyte, have been known for some time. Solid oxide electrochemical cells are characterized by their ability to perform electrochemical reactions with high efficiency in high-temperature environments, and are broadly classified into solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). Solid oxide electrolysis cells are devices that decompose fuel gas using electrical energy. Solid oxide fuel cells are devices that generate electrical energy (i.e., generate electricity) by combining multiple different gases. Hereinafter, the former may be simply referred to as "SOECs," and the latter may be simply referred to as "SOFCs."

[0003] Generally, whether such electrochemical cells are used for electrolysis or power generation, they are used as a cell stack in which a plurality of electrochemical unit cells (hereinafter also referred to as "unit cells") are stacked in a predetermined direction. For example, Patent Document 1 describes a cell stack of SOFCs. The unit cell includes a solid electrolyte layer, an air electrode disposed on its front side, and an anode disposed on its back side. Each unit cell in the cell stack is disposed in a space partitioned for each unit cell. This space is further partitioned into an air chamber and a fuel chamber. The unit cell is disposed so that the air electrode is exposed to the air chamber and the anode is exposed to the fuel chamber, and also serves as a partition member that partitions the air chamber and the fuel chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-36443 Summary of the Invention

[0005] When a cell stack is operated by supplying gas to both the air chamber and the fuel chamber, a load acts on the unit cell due to the pressure difference between the gas in the air chamber and the gas in the fuel chamber, concentrating stress on the anode, which can cause cracks in the anode (particularly on its outer periphery).Cracks in the anode reduce the reaction efficiency of the unit cell and deteriorate the performance of the cell stack.

[0006] The present invention has been made to address the above-mentioned problems, and one of the objects of the present invention is to provide a technology that can appropriately suppress the occurrence of anode cracking in electrochemical unit cells during operation of a cell stack.

[0007] The solid oxide electrochemical unit cell according to the present invention comprises: a solid electrolyte layer (12); an air electrode (14) laminated on the surface side of the solid electrolyte layer; a fuel electrode (16) laminated on the back surface of the solid electrolyte layer; a reinforcing portion (20) laminated on at least a part of the outer periphery of the back surface of the fuel electrode, which is the surface opposite to the solid electrolyte layer side; Equipped with The thermal expansion coefficient of the reinforcing portion is smaller than the thermal expansion coefficient of the fuel electrode. When the fuel electrode is composed of multiple layers, the "thermal expansion coefficient of the fuel electrode" refers to the thermal expansion coefficient of the layer that is in contact with the reinforcing portion among the layers that make up the fuel electrode.

[0008] Generally, electrochemical single cells are manufactured by laminating and pressing green sheets constituting each layer to form a laminate, and then firing the laminate. The firing process includes a temperature-raising process and a temperature-lowering process. In the temperature-raising process, the laminate is sintered to form a fired body. In the subsequent temperature-lowering process, the fired body tends to shrink based on the thermal expansion coefficients of the layers. In the electrochemical single cell according to the present invention, a reinforcing member having a thermal expansion coefficient smaller than that of the fuel electrode is laminated and disposed on at least a portion of the outer periphery of the back surface of the fuel electrode (the surface opposite the solid electrolyte layer). Therefore, the reinforcing member restrains the contraction of the fuel electrode during the temperature-lowering process (specifically, the contraction of the fuel electrode at the portion where the reinforcing member is provided). As a result, compressive stress directed toward the center is generated on the back surface of the reinforcing member (the surface opposite the fuel electrode). Therefore, even if a load acts on the electrochemical single cell during cell stack operation, causing stress to concentrate on the fuel electrode, the compressive stress applied to the reinforcing member makes the fuel electrode (specifically, the portion of the fuel electrode where the reinforcing member is provided) less likely to crack. Therefore, the configuration of the present invention can appropriately suppress the occurrence of anode cracking during operation of the cell stack. In the electrochemical unit cell of the present invention, the reinforcing portion is provided in at least a portion of the outer periphery of the back surface of the anode. Generally, anode cracking is likely to occur in the outer periphery. Therefore, by selectively providing the reinforcing portion in the portion where anode cracking is likely to occur, the occurrence of anode cracking can be appropriately suppressed while maintaining good diffusibility of gas passing through the electrochemical unit cell.

[0009] In one aspect of the invention, The reinforcing portion (20) surrounds the outer periphery of the rear surface of the fuel electrode (16).

[0010] This configuration makes it possible to more appropriately suppress the occurrence of cracks in the fuel electrode.

[0011] In one aspect of the invention, The reinforcing portion (20) is made of the same material as the solid electrolyte layer (12).

[0012] This configuration can reduce the possibility of an increase in the number of steps and costs during manufacturing due to the provision of a reinforcing portion in the electrochemical unit cell.

[0013] In one aspect of the invention, the solid electrolyte layer (12) and the reinforcing portion (20) contain zirconia, The zirconia content of the reinforcing portion is higher than the zirconia content of the solid electrolyte layer.

[0014] Generally, the higher the zirconia content of an object, the stronger the object. Therefore, with this configuration, the strength of the reinforcing portion is greater than the strength of the solid electrolyte layer, making the anode less susceptible to the effects of load in the area where the reinforcing portion is stacked. Therefore, the occurrence of anode cracking can be more appropriately suppressed.

[0015] In one aspect of the invention, the anode (16) includes a first layer (18a) in contact with the reinforcing portion (20), and a second layer (18b) laminated between a front surface of the first layer that faces the solid electrolyte layer (12) and a back surface of the solid electrolyte layer, the first layer is a support layer having a thickness greater than that of the solid electrolyte layer, the air electrode (14), the reinforcing portion (20), and the second layer; The second layer is a functional layer that is denser than the first layer.

[0016] According to this configuration, even in the case of an anode-supported electrochemical unit cell, the occurrence of anode cracking during operation of the cell stack can be appropriately suppressed.

[0017] The interconnector assembly of the present invention comprises: an electrochemical single cell (10); an interconnector (4) electrically connected to the electrochemical single cell; Equipped with the interconnector has a plurality of protruding portions (4a1 to 4a7) protruding toward the air electrode (14), and the protruding surfaces of the plurality of protruding portions are in contact with a surface of the air electrode that is the surface opposite to the solid electrolyte layer (12), The reinforcing portion (20) overlaps in the stacking direction with at least a part of the contact surfaces (f1 to f7) between the plurality of protrusions and the air electrode.

[0018] The interconnector assembly is a component of a cell stack. When the pressure difference between the gas in the air chamber and the gas in the fuel chamber increases during operation of the cell stack, an external force toward the electrochemical unit cell may act on the interconnector. In this case, loads from the multiple protrusions of the interconnector act on the anode via the air electrode and the solid electrolyte layer, concentrating stress on the anode and potentially causing anode cracking. Such anode cracking is likely to occur in "a portion of the region where the loads from the multiple protrusions are transmitted, located on the outer periphery of the anode." Here, "a region where the loads from the multiple protrusions are transmitted" refers to a region where the anode overlaps the contact surface (the surface where the protruding surfaces of the multiple protrusions contact the surface of the air electrode) in the stacking direction. In the interconnector assembly according to the present invention, a reinforcing member is laminated on at least a portion of the outer periphery of the back surface of the anode, and is positioned so as to overlap at least a portion of the contact surface in the stacking direction. Therefore, even if stress concentrates on the anode due to the load from the interconnector during operation of the cell stack, the reinforcing member applies compressive stress, making the anode less susceptible to cracking in the overlapping portion. In this way, by selectively providing a reinforcing portion in a portion where the anode cracking is likely to occur, it is possible to appropriately suppress the occurrence of the anode cracking while maintaining favorable diffusibility of the gas passing through the electrochemical unit cell.

[0019] In one aspect of the invention, The air electrode (14) has a polygonal shape in a plan view, The reinforcing portion (20) overlaps the contact surfaces (f1 to f7) in the stacking direction at least at one corner (C1 to C4) of the air electrode.

[0020] Anode cracking due to the load from the interconnector is particularly likely to occur in the area where the anode contact surface and the cathode overlap in the stacking direction at the corners. Therefore, this configuration can more appropriately suppress anode cracking.

[0021] In one aspect of the invention, The reinforcing portion (20) surrounds the outer periphery of the back surface of the fuel electrode (16) and overlaps the contact surfaces (f1 to f7) and all corners (C1 to C4) of the air electrode (14) in the stacking direction.

[0022] This configuration can more appropriately suppress the occurrence of fuel electrode cracking.

[0023] The cell stack according to the present invention comprises: A plurality of interconnector assemblies (40) are stacked in the stacking direction.

[0024] This configuration reduces the possibility of the cell stack characteristics deteriorating due to fuel electrode cracking.

[0025] The hot module according to the present invention comprises: A cell stack (1), a heat exchanger (33) for exchanging heat with the gas supplied to the cell stack; a heater (34) for heating the cell stack; a heat insulating material (35) in which the cell stack, the heat exchanger, and the heater are disposed; Equipped with.

[0026] The gas production device according to the present invention comprises: The electrochemical unit cells (10) each include a hot module (31) used in an operation mode in which they are used as electrolysis unit cells.

[0027] In the above description, in order to facilitate understanding of the invention, the symbols used in the embodiments are added in parentheses to the constituent elements of the invention corresponding to the embodiments, but each constituent element of the invention is not limited to the embodiments defined by the symbols. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a perspective view of a cell stack of a solid oxide electrolysis cell (SOEC) according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is an enlarged view of a single electrolytic cell included in the cross-sectional view of FIG. 2. [Figure 4] FIG. 2 is a bottom view of the electrolysis unit cell excluding the reinforcing portion. [Figure 5] FIG. 2 is a bottom view of the single electrolytic cell. [Figure 6] 3 is an enlarged view of an interconnector assembly included in the cross-sectional view of FIG. 2. FIG. [Figure 7] 7 is an enlarged view of an interconnector assembly included in the cross section taken along line VII-VII in FIG. [Figure 8] FIG. 10 is a bottom view of the interconnector assembly. [Figure 9] FIG. 1 is a block diagram of a gas production device equipped with a hot module. [Figure 10] FIG. 1 is a diagram showing a jig and a sample used in strength measurement. [Figure 11A] FIG. 2 is a cross-sectional view in the thickness direction of a sample for an electrolytic single cell according to an embodiment of the present invention. [Figure 11B] FIG. 1 is a cross-sectional view in the thickness direction of a sample for a conventional electrolytic single cell. DETAILED DESCRIPTION OF THE INVENTION

[0029] A cell stack, an electrochemical unit cell, an interconnector assembly, a gas production apparatus, and a hot module according to embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a solid oxide electrolysis cell (i.e., SOEC) will be described as an example. FIG. 1 is a perspective view of a cell stack 1 of an SOEC, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 . As shown in FIGS. 1 and 2 , the cell stack 1 includes an electrochemical unit group formed by stacking a plurality of rectangular flat-plate-shaped electrolysis units Ue in the thickness direction (vertical direction), and a pair of end plates 2, 3 disposed on the upper and lower surfaces of the electrochemical unit group, respectively. A Cartesian coordinate system is established for the cell stack 1. The x-axis extends along the width direction of the cell stack 1, the y-axis extends along the depth direction of the cell stack 1, and the z-axis extends along the thickness direction of the cell stack 1. In this embodiment, the upper side (+z-axis direction) corresponds to an example of a "front side," and the lower side (-z-axis direction) corresponds to an example of a "rear side." The electrolysis unit Ue is the smallest unit that functions as an electrolyzer (details will be described later). The end plates 2 and 3 are each a rectangular, flat member having the same outer shape as the electrolysis unit Ue, with a rectangular opening formed in the center. The electrolysis unit group and the end plates 2 and 3 are fastened to each other at their four corners by bolts Bo that penetrate the end plates 2 and 3 in the thickness direction and by nuts (not shown). The end plates 2 and 3 are made of metal (for example, stainless steel) and function as an anode and a cathode, respectively, when a voltage is applied. For ease of explanation, the proportions of the components in the drawings may differ from the actual proportions.

[0030] The electrolysis unit Ue will be described in detail with reference to Fig. 2. As shown in Fig. 2, the electrolysis unit Ue comprises unit cells 10, interconnectors 4, separators 5, an air electrode frame 6, an anode frame 7, and current collectors 8. The unit cells 10 and the interconnectors 4 constitute an interconnector assembly 40.

[0031] The unit cell 10 is the smallest unit of an SOEC (i.e., a solid oxide electrolysis unit cell) and includes a solid electrolyte layer 12, an air electrode 14 laminated on its upper surface, an anode 16 laminated on its lower surface, and a reinforcing portion 20 laminated on the lower surface of the anode 16. The air electrode 14 has a smaller outer shape than the solid electrolyte layer 12, the anode 16, and the reinforcing portion 20, and is disposed in the center of the upper surface of the solid electrolyte layer 12 in a plan view of the unit cell 10. Therefore, the outer periphery of the upper surface of the solid electrolyte layer 12 is exposed to the outside. The reinforcing portion 20 is disposed so as to surround the outer periphery of the anode 16. Therefore, the center of the lower surface of the anode 16 is exposed to the outside.

[0032] The interconnector 4 is a rectangular metal (for example, stainless steel) member that has a current collecting part 4a that protrudes downward from the centre of its lower surface (described later). A pair of interconnectors 4 is arranged on both sides of the unit cell 10 in the thickness direction. Two adjacent electrolysis units Ue share one interconnector 4. In other words, the interconnector 4 also functions as a separator that separates the two adjacent electrolysis units Ue. The lower surface of the current collecting part 4a is in contact with the upper surface of the air electrode 14 of the unit cell 10 (described later). The lower electrolysis unit Ue includes a pair of interconnectors 4, 9 instead of the pair of interconnectors 4, 4. The interconnector 9 is arranged at the bottom of the cell stack 1 and differs from the interconnector 4 in that it does not have a current collecting part 4a.

[0033] The separator 5 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in the center. The periphery of the opening of the separator 5 is brazed to the outer periphery of the upper surface of the solid electrolyte layer 12 of the unit cell 10 with a brazing material (e.g., Ag brazing), not shown. The separator 5 prevents the gas generated at the air electrode and the gas generated at the fuel electrode by electrolysis of the fuel gas (described below) from mixing.

[0034] The air electrode frame 6 is a rectangular plate-shaped insulating member and may be formed of, for example, a mica sheet. A rectangular opening is formed in the center of the air electrode frame 6. The air electrode frame 6 is disposed so as to be interposed between the interconnector 4 (strictly speaking, the upper interconnector in the electrolysis unit Ue) and the separator 5.

[0035] The fuel electrode frame 7 is a rectangular plate-shaped metal (for example, stainless steel) member with a square opening formed in its center. The fuel electrode frame 7 is disposed so as to be interposed between the separator 5 and the interconnector 4 (strictly speaking, the lower interconnector in the electrolysis unit Ue).

[0036] The internal space of the electrolysis unit Ue is partitioned into an air chamber Sa and a fuel chamber Sf. The air chamber Sa is a space that allows the "gas supplied to the air chamber Sa" and the "gas generated at the air electrode 14" to flow through. The air chamber Sa is comprised of an upper interconnector 4, a separator 5, an air electrode frame 6, and a single cell 10. The fuel chamber Sf is a space that allows the "gas supplied to the fuel chamber Sf" and the "gas generated at the fuel electrode 16" to flow through. The fuel chamber Sf is comprised of a separator 5, a lower interconnector 4, an anode frame 7, and a single cell 10. The air chamber Sa and the fuel chamber Sf will be described later.

[0037] The current collector 8 is a rectangular porous member made of metal (for example, nickel) that is smaller than the fuel electrode 16 in a plan view and allows gas generated at the fuel electrode 16 to pass through. The current collector 8 is arranged in the fuel chamber Sf so as to contact the center of the lower surface of the fuel electrode 16 and the upper surface of the lower interconnector 4. Two adjacent unit cells 10 are stacked in the thickness direction so as to share the interconnector 4 via the current collector 8, thereby electrically connecting the unit cells 10 in series.

[0038] 1 and 2, four paths Pfi, Pfo, Pai, and Pao are formed as gas flow paths on the outer periphery of the cell stack 1. These paths Pfi, Pfo, Pai, and Pao are each formed to penetrate members of the cell stack 1 in the thickness direction, excluding the "end plate 2" and the "interconnector 4 above the upper electrolysis unit Ue."

[0039] The path Pfi is formed along side E1, which is one of the four sides that make up the outer periphery of the cell stack 1, near one corner of side E1. The path Pfo is formed along side E2 that faces side E1, near the other corner of side E2 (the corner located diagonally from the one corner of side E1). The path Pfi communicates with the fuel chamber Sf via a horizontal hole (not shown) formed in the anode frame 7 of each electrolysis unit Ue. The path Pfo communicates with the fuel chamber Sf via a horizontal hole 7h (see FIG. 2 ) formed in the anode frame 7 of each electrolysis unit Ue.

[0040] The path Pai is formed along the side E2 and near one corner of the side E2. The path Pao is formed along the side E1 and near the other corner of the side E1. The path Pai is in communication with the air chamber Sa via a horizontal hole (not shown) formed in the air electrode frame 6 of each electrolysis unit Ue. The path Pao is in communication with the air chamber Sa via a horizontal hole 6h (see FIG. 2 ) formed in the air electrode frame 6 of each electrolysis unit Ue.

[0041] Next, the configuration of the unit cell 10 will be described in more detail with reference to Figures 3 to 5. Figure 3 is an enlarged view of the unit cell 10 included in the cross-sectional view of Figure 2. Figure 4 is a bottom view of the unit cell 10. However, for ease of viewing, the reinforcing portion 20 is omitted. Figure 5 is a bottom view of the unit cell 10 (in other words, a view in which the reinforcing portion 20 is superimposed on Figure 4). Note that the size and thickness of each layer constituting the unit cell 10 are not limited to the values ​​described below.

[0042] 3, the solid electrolyte layer 12 is a substantially rectangular flat layer measuring 150 mm square and 3 to 30 μm thick, and is configured to contain YSZ (yttria-stabilized zirconia). The solid electrolyte layer 12 has high oxide ion conductivity.

[0043] The air electrode 14 is a roughly rectangular, flat layer with a thickness of 5 to 200 μm, and is configured to contain a perovskite oxide such as LSCF (lanthanum strontium cobalt iron oxide). The air electrode 14 has a functional layer and a current collecting layer (not shown). The current collecting layer is thicker than the functional layer and is disposed on top of the functional layer. The air electrode 14 has high electronic conductivity, allowing the current collecting layer to efficiently collect electrons.

[0044] The anode 16 is a layer in the shape of a roughly rectangular plate measuring 150 mm square, and is formed to have a thickness greater than that of the solid electrolyte layer 12 and the air electrode 14, 200 to 2000 μm in this embodiment. That is, the unit cell 10 is an anode-supported cell in which the solid electrolyte layer 12 and the air electrode 14 are supported by the anode 16. The anode 16 has a support layer 18a and a functional layer 18b. The support layer 18a is significantly thicker than the functional layer 18b. The functional layer 18b is laminated and disposed between the upper surface of the support layer 18a and the lower surface of the solid electrolyte layer 12.

[0045] The support layer 18a is a cermet of nickel and YSZ, and is configured to be porous, including a plurality of micropores (not shown). The diameter of the micropores is on the order of several μm, which ensures the permeability of the fuel gas described below. The functional layer 18b is similar to the support layer 18a in that it is a cermet of nickel and YSZ, but differs from the support layer 18a in that it is formed more densely than the support layer 18a. The fuel electrode 16 has high electronic conductivity.

[0046] The reinforcing portion 20 is a frame-shaped layer that is 150 mm square and 3 to 30 μm thick, and is made of the same material as the solid electrolyte layer 12. In this embodiment, the grain size of the reinforcing portion 20 is the same as the grain size of the solid electrolyte layer 12. The reinforcing portion 20 is layered on the lower surface of the support layer 18a so as to surround the outer periphery of the support layer 18a.

[0047] The reinforcing portion 20 has a smaller thermal expansion coefficient than the support layer 18a. In this embodiment, the reinforcing portion 20 is made of the same material as the solid electrolyte layer 12, and therefore the solid electrolyte layer 12 also has a smaller thermal expansion coefficient than the support layer 18a. The material of the reinforcing portion 20 may be different from the material of the solid electrolyte layer 12. In this case, however, it is desirable to select materials that satisfy the following relationship: "The difference between the thermal expansion coefficient of the reinforcing portion 20 and the thermal expansion coefficient of the support layer 18a is equal to or less than the difference between the thermal expansion coefficient of the solid electrolyte layer 12 and the thermal expansion coefficient of the support layer 18a." Selecting a material that satisfies this relationship reduces the possibility of a decrease in yield of the unit cell 10 due to the fabrication of the reinforcing portion 20.

[0048] The positional relationship of the layers 12, 14, 16 (18a, 18b), and 20 of the unit cell 10 will be described in detail with reference to Figures 3 to 5. As shown in Figure 4, when the unit cell 10 (however, the reinforcing portion 20 is not shown) is viewed from below, the fuel electrode 16 has the same shape and size as the solid electrolyte layer 12. On the other hand, the air electrode 14 has approximately the same shape as the layers 16 and 12 but is smaller in size, so the entire outer periphery of the upper surface of the solid electrolyte layer 12 is exposed to the outside. The width of this exposed surface is constant except for the four corners of the solid electrolyte layer 12.

[0049] As shown in Fig. 5, when the unit cell 10 is viewed from the bottom, the outer periphery of the reinforcing portion 20 coincides with the outer periphery of the anode 16 and the solid electrolyte layer 12. Meanwhile, the inner periphery of the reinforcing portion 20 coincides with the inner periphery of the cathode 14 except for the four corners, and the four corners are located more inward than the inner periphery of the cathode 14. Therefore, the reinforcing portion 20 overlaps the four corners C1 to C4 of the cathode 14 in the thickness direction. Furthermore, because the reinforcing portion 20 is formed only on the outer periphery of the lower surface of the support layer 18a, the central portion of the lower surface of the support layer 18a is exposed to the outside.

[0050] Next, the interconnector assembly 40 will be described with reference to FIGS. 6 to 8. FIG. 6 is an enlarged view of the interconnector assembly 40 included in the cross-sectional view of FIG. 2. FIG. 7 is an enlarged view of the interconnector assembly 40 included in the cross-section taken along line VII-VII of FIG. 1. FIG. 8 is a bottom view of the interconnector assembly 40. As shown in FIGS. 6 to 8, the interconnector 4 has seven current collecting portions 4a1 to 4a7 protruding downward from the center of its bottom surface. The current collecting portions 4a1 to 4a7 have the same size and shape (rectangular flat plate-like) and are arranged at equal intervals in the y-axis direction so that the wide surfaces of two adjacent current collecting portions 4a face each other. The bottom surfaces of the current collecting portions 4a1 to 4a7 are in contact with the top surface of the air electrode 14 at surfaces f1 to f7 (see FIG. 8), respectively (strictly speaking, the two are bonded together at surfaces f1 to f7 with a conductive adhesive). This electrically connects the interconnector 4 to the unit cell 10. The current collecting portions 4a (4a1 to 4a7) correspond to an example of a "protrusion," and their lower surfaces correspond to an example of a "protruding surface." Furthermore, the surfaces f1 to f7 each correspond to an example of a "contact surface."

[0051] As shown in FIGS. 6 to 8 , both ends in the x-axis direction of the current collecting portion 4a1 (the current collecting portion 4a1 to 4a7 located furthest in the negative y-axis direction) are located on the corners C1 and C2 of the air electrode 14. Both ends in the x-axis direction of the current collecting portion 4a7 (the current collecting portion 4a1 to 4a7 located furthest in the positive y-axis direction) are located on the corners C3 and C4 of the air electrode 14. As described above, the reinforcing portion 20 overlaps the corners C1 to C4 of the air electrode 14 in the thickness direction. Therefore, the reinforcing portion 20 overlaps the surface f1, which is the contact surface between the current collecting portion 4a1 and the air electrode 14, in the thickness direction at the corners C1 and C2. Similarly, the reinforcing portion 20 overlaps the surface f7, which is the contact surface between the current collecting portion 4a7 and the air electrode 14, in the thickness direction at the corners C3 and C4. In this embodiment, the number of current collecting portions 4a located at each of the corners C1 to C4 is one, but this is not limited to this configuration. The number of current collecting portions 4a located at each of the corners C1 to C4 can be determined depending on the size, shape, and number of the current collecting portions 4a.

[0052] 1 and 2, the explanation will be continued. The cell stack 1 can be operated in different operation modes depending on the type of fuel gas. The fuel gas is a gas to be electrolyzed, and can be, for example, "water vapor," "carbon dioxide," or a "mixture of water vapor and carbon dioxide." The fuel gas is supplied to the fuel chamber Sf together with a reducing gas. The reducing gas is a gas used to suppress oxidation of the catalyst contained in the anode 16. Hereinafter, the operation modes when the fuel gas is water vapor, carbon dioxide, or a mixture of these gases will be referred to as the "water vapor electrolysis mode," the "carbon dioxide electrolysis mode," and the "co-electrolysis mode," respectively.

[0053] The operation of the cell stack 1 will be described using an example in which it is operated in steam electrolysis mode using hydrogen as the reducing gas. First, a voltage is applied to the end plates 2 and 3 of the cell stack 1 from an external power source. Next, when a high-temperature mixed gas of steam (fuel gas) and hydrogen (reducing gas) is supplied from the path Pfi, the mixed gas flows into the fuel chamber Sf of each electrolysis unit Ue via a horizontal hole (not shown). Furthermore, when high-temperature air is supplied from the path Pai, the air flows into the air chamber Sa of each electrolysis unit Ue via a horizontal hole (not shown). The high-temperature air is supplied in order to control the temperature of the cell stack 1.

[0054] Water vapor that flows into the fuel chamber Sf passes through the support layer 18a of the fuel electrode 16 and travels to the functional layer 18b. Mainly in the functional layer 18b, the water vapor reacts with electrons (electrons supplied from the end plate 3 via the current collector 8) and is decomposed into hydrogen and oxide ions. The hydrogen diffuses within the fuel chamber Sf, is discharged through the horizontal hole 7h via path Pfo, and is collected by a known method. At this time, unreacted water vapor is discharged along with the hydrogen via path Pfo. Meanwhile, the oxide ions travel through the solid electrolyte layer 12 to the air electrode 14 in the air chamber Sa, where they release electrons at the functional layer of the air electrode 14 and become oxygen. The oxygen diffuses within the air chamber Sa, and is discharged through the horizontal hole 6h via path Pao together with the air that has flowed into the air chamber Sa and is collected by a known method. The electrons released from the functional layer are collected by the current collecting part 4a of the interconnector 4 via the current collecting layer and circulate from the end plate 2 to the end plate 3 via an external power source. As a result, a current corresponding to the applied voltage flows through the cell stack 1.

[0055] When the cell stack 1 is operated in the carbon dioxide electrolysis mode, carbon dioxide is electrolyzed to produce carbon monoxide and oxygen, and when the cell stack 1 is operated in the co-electrolysis mode, the mixed gas is electrolyzed to produce oxygen and a synthesis gas containing hydrogen and carbon monoxide. In either operation mode, carbon monoxide may be used instead of hydrogen as the reducing gas.

[0056] 9 is a block diagram of the gas production apparatus 30. The gas production apparatus 30 includes a hot module 31 and a condenser 36. The cell stack 1 is a component of the hot module 31. That is, the hot module 31 includes the cell stack 1, a vaporizer 32, a heat exchanger 33, a heater 34, and a heat insulator 35. Below, the gas production apparatus 30 and the hot module 31 will be described using an example in which they are operated in a steam electrolysis mode using hydrogen as the reducing gas.

[0057] The vaporizer 32 generates water vapor to be supplied to the cell stack 1. Specifically, the vaporizer 32 has a heat exchanger (not shown) that exchanges heat with high-temperature exhaust gas containing oxygen generated by the cell stack 1, and generates water vapor by heating the water with the heat obtained through the heat exchange. The heat exchanger 33 exchanges heat between the supply gas supplied to the cell stack 1 and the product gas generated by the cell stack 1. Specifically, the heat exchanger 33 exchanges heat between "water vapor generated by the vaporizer 32 (strictly speaking, water vapor containing hydrogen as a reducing gas)" and "hydrogen and oxygen generated by the cell stack 1," and also between "air" and "hydrogen and oxygen generated by the cell stack 1." The heater 34 heats the water vapor and air, which are supply gases after passing through the heat exchanger 33, to the operating temperature of the cell stack 1. After passing through the heater 34, the water vapor is supplied to the fuel chamber Sf through a path Pfi of the cell stack 1, and the air after passing through the heater 34 is supplied to the air chamber Sa through a path Pai of the cell stack 1.

[0058] Heat-resistant fibers such as ceramic wool, refractory ceramic fiber (RCF), and biosoluble fiber (AES), and / or a heat-resistant container made of these heat-resistant fibers, can be used for the heat insulating material 35. The cell stack 1, vaporizer 32, heat exchanger 33, and heater 34 are arranged inside the heat insulating material 35. The heat-resistant fibers are arranged so as to fill gaps between the cell stack 1, vaporizer 32, heat exchanger 33, and heater 34. This suppresses heat radiation from the cell stacks 1 and 32 to 34.

[0059] The condenser 36 is a device for cooling hydrogen containing unreacted water vapor. The water liquefied by the condenser 36 is supplied to the vaporizer 32 again as raw water.

[0060] In this way, when the cell stack 1 is operated in steam electrolysis mode, the gas production device 30 functions as a hydrogen production device. On the other hand, when the cell stack 1 is operated in carbon dioxide electrolysis mode, the gas production device 30 functions as a carbon monoxide production device, and when operated in co-electrolysis mode, the gas production device 30 functions as a synthesis gas production device. However, carbon dioxide undergoes heat exchange in a gaseous state in the heat exchanger 33. For this reason, in the carbon dioxide electrolysis mode and the co-electrolysis mode, the carbon dioxide is supplied to the heat exchanger 33 without passing through the vaporizer 32. Therefore, when the gas production device 30 is used only as a carbon monoxide production device, the vaporizer 32 is not required for the gas production device 30.

[0061] The unit cell 10 is manufactured as follows. First, butyral resin, dioctyl phthalate (DOP) as a plasticizer, a known dispersant, a mixed solvent of toluene and ethanol, and a pore-forming agent (typically organic beads) are added to a mixed powder of NiO (nickel oxide) powder and YSZ powder in predetermined proportions, and the mixture is mixed in a ball mill to prepare a slurry. Then, a doctor blade method is used to produce a green sheet of the support layer 18a of the anode 16 having a predetermined thickness from the slurry. The mixing ratio of the NiO powder and the YSZ powder can be appropriately set depending on the performance required of the support layer 18a. Note that the pore-forming agent does not necessarily have to be added.

[0062] Next, butyral resin, DOP as a plasticizer, a known dispersant, and a mixed solvent of toluene and ethanol are added to the YSZ powder in predetermined proportions and mixed in a ball mill to prepare a slurry. A doctor blade method is then used to fabricate a green sheet of the solid electrolyte layer 12 having a predetermined thickness from the slurry. The slurry is adjusted so that its shrinkage during the temperature-lowering step during firing, described below, is greater than that of the slurry for the green sheet of the support layer 18a. Extra slurry is prepared because it will be used for purposes other than the green sheet (described below).

[0063] Next, butyral resin, dioctyl phthalate (DOP) as a plasticizer, a known dispersant, and a mixed solvent of toluene and ethanol are added to the mixed powder of NiO powder and YSZ powder in predetermined ratios, and the mixture is mixed in a ball mill to prepare a slurry. A green sheet of the functional layer 18b of the anode 16 having a predetermined thickness is then fabricated from the slurry on the green sheet of the solid electrolyte layer 12 using a doctor blade method. This results in a two-layer sheet A consisting of the green sheet of the solid electrolyte layer 12 and the green sheet of the functional layer 18b. The mixing ratio of the NiO powder and the YSZ powder can be appropriately set depending on the performance required of the functional layer 18b.

[0064] Next, the excess slurry prepared during the green sheet deposition of the solid electrolyte layer 12 is heat-treated at several hundred degrees. This degreases the slurry and turns it into powder. A soluble resin is then added to the powder and kneaded to form a paste. For example, ethyl cellulose dissolved in terpineol solvent is used as the soluble resin.

[0065] Next, the paste is screen-printed onto the green sheet of the support layer 18a in a predetermined pattern (see FIG. 5) to form a paste layer of the reinforcing portion 20. This produces a sheet B consisting of the green sheet of the support layer 18a and the paste layer of the reinforcing portion 20. By forming the material for the paste layer of the reinforcing portion 20 from a slurry equivalent to the slurry constituting the green sheet of the solid electrolyte layer 12 in this way, the particle size of the paste layer of the reinforcing portion 20 can be made the same as the particle size of the green sheet of the solid electrolyte layer 12. However, the particle sizes of the two do not necessarily have to be the same.

[0066] Then, sheet A is placed on sheet B so that the surface of the "green sheet for functional layer 18b" opposite the green sheet side of solid electrolyte layer 12 overlaps the surface of the "green sheet for support layer 18a" opposite the paste layer side of reinforcing portion 20, and the sheets are laminated and pressed together by warm isostatic pressing (WIP) to produce a laminate. Warm isostatic pressing is performed, for example, for 35 seconds under an environment of a water temperature of 70°C and a water pressure of 12.9 MPa, but is not limited to these conditions. Note that pressing may also be performed using a vacuum high-pressure press, and the method of lamination and pressing is not limited.

[0067] Next, the laminate is cut in the thickness direction to separate unit laminate bodies, and each unit laminate body is heat-treated on a honeycomb setter at several hundred degrees. This degreasing removes the resin and pore-forming agent. The unit laminate body is then fired (primary firing) at a predetermined first temperature (e.g., 1300 to 1400°C) for a predetermined time (e.g., 10 to 24 hours). This firing process includes a temperature-raising process and a temperature-lowering process. During the temperature-raising process, the unit laminate body is sintered to form a fired body including the solid electrolyte layer 12, the functional layer 18b, the support layer 18a, and the reinforcing portion 20. In this embodiment, the particle size of the paste layer of the reinforcing portion 20 is equal to the particle size of the green sheet of the solid electrolyte layer 12, so during the temperature-raising process, both layers begin sintering at the same time. This reduces the possibility of a decrease in the yield of the unit cell 10 due to the fabrication of the reinforcing portion 20. During the subsequent temperature-lowering process, the fired body attempts to shrink based on the thermal expansion coefficients of each layer. At this time, since the thermal expansion coefficient of the reinforcing portion 20 is smaller than that of the support layer 18a, the contraction of the support layer 18a (strictly speaking, the contraction of the support layer 18a in the portion where the reinforcing portion 20 is provided) is restrained by the reinforcing portion 20, and as a result, compressive stress directed toward the center is generated on the surface of the reinforcing portion 20 opposite the support layer 18a side.

[0068] Next, the fired body is placed on a setter with the reinforcing part 20 facing downward, another setter that functions as a weight is placed on the fired body, and the fired body is fired at a first temperature for a predetermined time (e.g., 3 hours) to correct any warping that has occurred in the fired body during the firing process.

[0069] Thereafter, a material containing LSCF is screen-printed on the center of the upper surface of the solid electrolyte layer 12 to form a paste layer for the air electrode 14. This is then fired (secondary firing) at a predetermined second temperature (e.g., 900 to 1000°C) for a predetermined time (e.g., 1 to 5 hours), causing the paste layer for the air electrode 14 to shrink and sinter based on a predetermined thermal expansion coefficient, thereby forming the air electrode 14. The second temperature is set to a temperature lower than the first temperature. The single cell 10 is thus manufactured.

[0070] The inventors of the present application performed four-point bending strength measurements to examine the extent to which the strength of the unit cell 10 is improved compared to that of a conventional unit cell. FIG. 10 shows jigs 50 and 60 used in the strength measurements and a sample S. FIG. 11A is a cross-sectional view in the thickness direction of a sample S1 for the unit cell 10. FIG. 11B is a cross-sectional view in the thickness direction of a sample S2 for a conventional unit cell. As shown in FIG. 10, the jigs 50 and 60 are both cylindrical, and the jig 60 has a larger diameter than the jig 50. The jigs 50 and 60 are each held by a holding member (not shown) so that they are coaxial along the z-axis direction. The holding member is configured to allow the jigs 50 and 60 to be moved independently in the z-axis direction. The sample S is in the shape of a circular flat plate.

[0071] In this measurement, samples S1 and S2 are used as the sample S. As shown in FIG. 11A, sample S1 is a sintered body including a layer 112, a layer 116 disposed over the entire lower surface of layer 112, and a layer 120 disposed over the entire lower surface of layer 116. Layer 116 includes layers 118a and 118b. The compositions of layers 112, 118a, 118b, and 120 are the same as the compositions of the solid electrolyte layer 12, support layer 18a, functional layer 18b, and reinforcing portion 20 of the unit cell 10, respectively. Sample S1 is manufactured using the same manufacturing method as the unit cell 10 (excluding the manufacturing process of the air electrode 14). On the other hand, as shown in FIG. 11B, sample S2 has the same configuration as sample S1 except that it does not include layer 120. Sample S2 is manufactured by primary firing a laminate not including layer 120 and correcting warpage.

[0072] Four-point bending strength measurement is performed as follows. First, the sample S is placed between the jigs 50 and 60 so that the sample S is coaxial with the jigs 50 and 60. Next, the jig 50 is moved downward and the jig 60 is moved upward using a holding member, thereby clamping the sample S between the jigs 50 and 60. Next, a downward external force is applied to the jig 50 while the jig 60 is fixed. As a result, at an arbitrary cross section in the thickness direction passing through the center of the sample S, the sample S receives a downward load from the jig 50 at two contact points and an upward load from the jig 60 at two contact points (contact points located radially outward from the contact points with the jig 50). In other words, the sample S receives loads from four contact points. The inventors increased the external force applied to the jig 50 and measured the load acting on the sample S just before it broke as the maximum load. In addition, the four-point bending strength of the sample S was calculated using a well-known calculation formula. Eight samples were used for each of samples S1 and S2 (n=8).

[0073] As a result, the average maximum load of sample S2 was 45 N, while the average maximum load of sample S1 was 66 N. Furthermore, the average four-point bending strength of sample S2 was 193 MPa, while the average four-point bending strength of sample S1 was 271 MPa. From the above, it was confirmed that the load-bearing capacity and bending strength of sample S1 were significantly improved compared to sample S2. Based on these measurement results, it is believed that the load-bearing capacity and bending strength of unit cell 10 are significantly improved compared to conventional unit cells.

[0074] As described above, in the unit cell 10 according to this embodiment, the reinforcing portion 20, which has a thermal expansion coefficient smaller than that of the support layer 18a, is laminated and disposed on the outer periphery of the lower surface of the support layer 18a. With this configuration, compressive stress is applied to the lower surface of the reinforcing portion 20 during the manufacturing of the unit cell 10 (i.e., during the temperature-reducing step during primary firing). Therefore, even if a load acts on the unit cell 10 during operation of the cell stack 1, causing stress to concentrate on the anode 16, the anode 16 (strictly speaking, the portion of the anode 16 where the reinforcing portion 20 is provided) is less likely to crack. In other words, the tensile stress generated in the anode 16 is offset by the compressive stress applied to the lower surface of the reinforcing portion 20. Therefore, the occurrence of cracks in the anode 16 can be appropriately suppressed while maintaining good diffusibility of gas passing through the unit cell 10.

[0075] In particular, in this embodiment, the reinforcing portion 20 is provided so as to surround the outer periphery of the lower surface of the support layer 18a, which makes it possible to more appropriately prevent the occurrence of cracks in the fuel electrode 16.

[0076] Additionally, in this embodiment, the inner periphery of the reinforcing section 20, excluding the four corners, coincides with the inner periphery of the air electrode 14. If the inner periphery of the reinforcing section 20, excluding the four corners, is located more inward than the inner periphery of the air electrode 14, the area of ​​overlap between the reinforcing section 20 and the air electrode 14 in the thickness direction increases, which may reduce gas diffusibility. On the other hand, if the inner periphery of the reinforcing section 20, excluding the four corners, is located more outward than the inner periphery of the air electrode 14, the width of the frame-shaped reinforcing section 20 becomes excessively narrow, which reduces the degree to which anode cracking is suppressed. Therefore, this configuration can appropriately suppress anode cracking while preventing a decrease in gas diffusibility.

[0077] Furthermore, since the reinforcing portion 20 is made of the same material as the solid electrolyte layer 12, the possibility of an increase in the number of steps and costs during manufacturing due to the unit cell 10 being provided with the reinforcing portion 20 can be reduced.

[0078] Furthermore, in the interconnector assembly 40 according to this embodiment, the reinforcing portion 20 overlaps in the stacking direction with the faces f1 and f7 at all corners C1 to C4 of the air electrode 14. Anode cracking caused by the load from the current collecting portions 4a1 to 4a7 of the interconnector 4 is particularly likely to occur in the portions of the anode 16 where the faces f1 to f7 overlap with the corners C1 to C4 of the air electrode 14 in the stacking direction. Therefore, with this configuration, the occurrence of cracking in the anode 16 can be further appropriately suppressed.

[0079] The electrochemical single cell, interconnector assembly, cell stack, hot module, and gas production apparatus according to the embodiments have been described above, but the present invention is not limited to the above embodiments, and various modifications are possible as long as they do not deviate from the purpose of the present invention.

[0080] For example, the type of unit cell 10 is not important as long as it is a solid oxide electrochemical unit cell. That is, the unit cell 10 may be configured to function as a SOFC unit cell. Furthermore, the unit cell 10 may be configured to have both SOEC and SOFC functions (i.e., to function reversibly).

[0081] Furthermore, the reinforcing portion 20 does not need to surround the entire outer periphery of the lower surface of the fuel electrode 16 (in the embodiment, the support layer 18a), but may be configured to be provided partially on the outer periphery.

[0082] Furthermore, in a bottom view of the unit cell 10, the inner periphery of the reinforcing portion 20 other than the four corners does not necessarily have to coincide with the inner periphery of the air electrode 14, and may be located either on the outer periphery or on the inner periphery of the inner periphery of the air electrode 14. Note that, in a plan view, the shape of the air electrode 14 is not limited to a rectangular shape and may be a polygonal shape other than a rectangular shape.

[0083] Furthermore, the unit cell 10 is not limited to an anode-supported type, and may be configured as, for example, an electrolyte-supported type. In this case, since the anode does not include a support layer, the reinforcing portion can be laminated on at least a part of the outer periphery of the back surface of the functional layer.

[0084] Furthermore, the solid electrolyte layer 12 and the reinforcing portion 20 may be made of a material containing zirconia. In this case, it is desirable that the zirconia content of the reinforcing portion 20 be higher than that of the solid electrolyte layer 12. Generally, the higher the zirconia content of an object, the stronger the object. Therefore, with this configuration, the strength of the reinforcing portion 20 is higher than that of the solid electrolyte layer 12, making the fuel electrode 16 in the portion where the reinforcing portion 20 is stacked less susceptible to the effects of load. Therefore, the occurrence of cracks in the fuel electrode 16 can be more appropriately suppressed. The additive material may be different between the solid electrolyte layer 12 and the reinforcing portion 20.

[0085] Furthermore, a reaction prevention layer may be formed between the solid electrolyte layer 12 and the air electrode 14, and a diffusion prevention layer may be formed between the solid electrolyte layer 12 and the fuel electrode 16.

[0086] Furthermore, the present invention may include the following aspects. [1] a solid electrolyte layer; an air electrode disposed on the surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; a reinforcing portion disposed on at least a portion of the outer periphery of a back surface of the fuel electrode, the back surface being the surface opposite to the solid electrolyte layer side; Equipped with The thermal expansion coefficient of the reinforcing portion is smaller than the thermal expansion coefficient of the anode. Solid oxide electrochemical single cell. [2] [1] The electrochemical unit cell according to [1], the reinforcing portion surrounds the outer periphery of the back surface of the fuel electrode. Electrochemical single cell. [3] The electrochemical unit cell according to [1] or [2], The reinforcing portion is made of the same material as the solid electrolyte layer. Electrochemical single cell. [4] The electrochemical unit cell according to [1] or [2], the solid electrolyte layer and the reinforcing portion contain zirconia, the zirconia content of the reinforcing portion is higher than the zirconia content of the solid electrolyte layer; Electrochemical single cell. [5] The electrochemical unit cell according to any one of [1] to [4], the anode includes a first layer in contact with the reinforcing portion, and a second layer laminated between a front surface of the first layer facing the solid electrolyte layer and a back surface of the solid electrolyte layer, the first layer is a support layer having a thickness greater than that of the solid electrolyte layer, the air electrode, the reinforcing portion, and the second layer; The second layer is a functional layer that is denser than the first layer. Anode-supported electrochemical unit cell. [6] [1] to [5], and the electrochemical unit cell according to any one of [1] to [5]; an interconnector electrically connected to the electrochemical unit cell; Equipped with the interconnector has a plurality of protruding portions protruding toward the air electrode, and the protruding surfaces of the plurality of protruding portions are in contact with a surface of the air electrode that is a surface opposite to the solid electrolyte layer side, the reinforcing portion overlaps in the stacking direction with at least a portion of the contact surface between the plurality of protrusions and the air electrode. Interconnector joint. [7] [6] The interconnector assembly according to [6], the air electrode has a polygonal shape in a plan view, the reinforcing portion overlaps the contact surface in the stacking direction at least at one corner of the air electrode. Interconnector joint. [8] [7] The interconnector assembly according to [7], the reinforcing portion surrounds the outer periphery of the rear surface of the fuel electrode and overlaps the contact surface and all corners of the air electrode in the stacking direction. Interconnector joint. [9] A cell stack formed by stacking a plurality of interconnector assemblies according to any one of [6] to [8] in the stacking direction.

[10] [9] The cell stack according to [9], a heat exchanger that exchanges heat with the gas supplied to the cell stack; a heater for heating the cell stack; a heat insulating material in which the cell stack, the heat exchanger, and the heater are disposed; Equipped with Hot module.

[11]

[10] The hot module is used in an operation mode in which each of the plurality of electrochemical single cells is used as an electrolysis single cell. Gas production equipment. [Explanation of symbols]

[0087] 1: cell stack, 2: end plate, 3: end plate, 4: interconnector, 4a: current collecting part, 5: separator, 6: air electrode frame, 7: fuel electrode frame, 8: current collector, 9: (lowest) interconnector, 10: solid oxide electrolysis unit cell, 12: solid electrolyte layer, 14: air electrode, 16: fuel electrode, 18a: support layer, 18b: functional layer, 20: reinforcing part, 30: gas production device, 31: hot module, 32: vaporizer, 33: heat exchanger, 34: heater, 35: heat insulating material, 36: condenser, 40: interconnector assembly, 50: jig, 60: jig

Claims

1. a solid electrolyte layer; an air electrode disposed on a surface side of the solid electrolyte layer; a fuel electrode disposed on the back surface of the solid electrolyte layer; a reinforcing portion laminated on at least a part of the outer periphery of a back surface of the fuel electrode, the back surface being the surface opposite to the solid electrolyte layer side; Equipped with The thermal expansion coefficient of the reinforcing portion is smaller than the thermal expansion coefficient of the anode. Solid oxide electrochemical single cell.

2. 10. The electrochemical unit cell of claim 1, the reinforcing portion surrounds the outer periphery of the back surface of the fuel electrode. Electrochemical single cell.

3. 10. The electrochemical unit cell of claim 1, The reinforcing portion is made of the same material as the solid electrolyte layer. Electrochemical single cell.

4. 10. The electrochemical unit cell of claim 1, the solid electrolyte layer and the reinforcing portion contain zirconia, the zirconia content of the reinforcing portion is higher than the zirconia content of the solid electrolyte layer; Electrochemical single cell.

5. 10. The electrochemical unit cell of claim 1, the anode includes a first layer in contact with the reinforcing portion, and a second layer laminated between a front surface of the first layer facing the solid electrolyte layer and a back surface of the solid electrolyte layer, the first layer is a support layer having a thickness greater than that of the solid electrolyte layer, the air electrode, the reinforcing portion, and the second layer; The second layer is a functional layer that is denser than the first layer. Anode-supported electrochemical unit cell.

6. The electrochemical unit cell according to any one of claims 1 to 5; an interconnector electrically connected to the electrochemical unit cell; Equipped with the interconnector has a plurality of protruding portions protruding toward the air electrode, and the protruding surfaces of the plurality of protruding portions are in contact with a surface of the air electrode that is a surface opposite to the solid electrolyte layer side, the reinforcing portion overlaps in the stacking direction with at least a portion of the contact surface between the plurality of protrusions and the air electrode. Interconnector joint.

7. 7. The interconnector assembly according to claim 6, the air electrode has a polygonal shape in a plan view, the reinforcing portion overlaps the contact surface in the stacking direction at least at one corner of the air electrode; Interconnector joint.

8. 8. The interconnector assembly according to claim 7, the reinforcing portion surrounds the outer periphery of the rear surface of the fuel electrode and overlaps the contact surface and all corners of the air electrode in the stacking direction. Interconnector joint.

9. A cell stack formed by stacking a plurality of interconnector assemblies according to claim 6 in the stacking direction.

10. The cell stack according to claim 9 ; a heat exchanger that exchanges heat with the gas supplied to the cell stack; a heater for heating the cell stack; a heat insulating material in which the cell stack, the heat exchanger, and the heater are disposed; Equipped with Hot module.

11. The hot module according to claim 10 is used in an operation mode in which each of the plurality of electrochemical unit cells is used as an electrolysis unit cell. Gas production equipment.

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