Solid oxide type electrochemical cell stack

Abstract

To provide a solid oxide type electrochemical cell stack that can suppress deformation such as bending of a cell caused by a pressure difference between electrodes while ensuring supply and diffusion of gas to the electrodes.SOLUTION: A solid oxide type electrochemical cell stack 10 includes a flat-plate type first electrochemical cell 13A, a flat-plate type second electrochemical cell 13B stacked with the first electrochemical cell 13A, a separator 12 that is electrically connected to a hydrogen electrode of the first electrochemical cell 13A and an oxygen electrode of the second electrochemical cell 13B, a first conductive member 17 for electrically connecting the hydrogen electrode of the first electrochemical cell 13A to the separator 12, and a second conductive member 18 for electrically connecting the oxygen electrode of the second electrochemical cell 13B to the separator 12. The second conductive member 18 includes a conductive porous member 21 that maintains supply and diffusion of gas, and a conductive structural support member 22 that restrains mechanical displacement of the electrochemical cell 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to a solid oxide electrochemical cell stack. [Background technology]

[0002] A solid oxide fuel cell (SOFC) is a device that reacts a reducing agent (hydrogen or hydrocarbon, etc.) with an oxidizing agent (oxygen, etc.) through a solid oxide electrolyte membrane with oxygen ion conductivity at an operating temperature of about 600 to 1000°C, and extracts the energy as electricity. In the unit cell, the electrode that plays the role of generating oxygen ions from oxygen gas and electrons is called the oxygen electrode, and the electrode that plays the role of separating hydrogen gas into hydrogen ions and electrons and generating water molecules from the hydrogen ions and oxygen ions is called the hydrogen electrode. On the other hand, a solid oxide electrolysis cell (SOEC / high-temperature steam electrolysis cell) is a device that obtains hydrogen and oxygen by electrolyzing high-temperature steam, and its operating principle is the reverse reaction of SOFC. Hereinafter, SOFC and SOEC are collectively referred to as solid oxide electrochemical cells (SOC).

[0003] Solid oxide electrochemical cells come in various shapes, such as flat, cylindrical, cylindrical flat, and honeycomb. Furthermore, a structure called a cell stack is formed by stacking and integrating multiple sheets of these cells. For example, a flat solid oxide electrochemical cell (hereinafter referred to as "flat cell") is configured to form a flat solid oxide electrochemical cell stack (hereinafter referred to as "flat cell stack") by stacking multiple sheets of the cell. A flat cell stack is configured from a unit cell unit (comprised of a flat cell, a conductive separator that isolates the atmospheres (supply and exhaust gases) of the oxygen and hydrogen electrodes in the flat cell from each other and electrically connects the electrodes of adjacent unit cells, and a support and insulating material that insulates the ends of adjacent cells), a bus bar (current supply terminal) for stacking each cell unit in series to pass current, and a clamping plate for sandwiching and integrating the whole.

[0004] In a cell stack in which flat-type cells are stacked, it is necessary to ensure electrical contact between the electrodes of the unit cells that are in contact with each other, and to prevent cell damage due to over-tightening while maintaining a space for supplying / generating gas to the oxygen electrode / hydrogen electrode in the part that supports the entire stack structure. Furthermore, the part that supports the above-mentioned entire stack structure needs to be insulated to prevent electrical shorts between adjacent cells in the stacking direction between the upper and lower fastening plates. For each unit cell unit, it is necessary to prevent gas leakage outside the stack at the ends (out-leak) and gas leakage between the oxygen electrode / hydrogen electrode at the interface at each cell end (cross-leak), and it is also necessary to suppress cracks and damage caused by distortion of the flat-type cells when a pressure difference occurs between the two electrodes.

[0005] For example, in a flat cell stack, when the gas pressure supplied to the hydrogen electrode becomes high, the center of the flat cell fixed at the end warps toward the oxygen electrode, which makes the cell more likely to crack. This tendency is more pronounced as the area of ​​the unit cell becomes larger and the cell thickness becomes thinner. To date, proposals have been made to suppress the curvature of the flat cell used in the stack, to control the particle structure and distribution in the thickness direction of the flat cell substrate, and to provide a structure that absorbs displacement at the joint between the cell end and the stack frame. However, no cell stack structure has been proposed so far that satisfies all of the above characteristics in practical operation, i.e., structural support, insulation, density, interface sealability, and differential pressure resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7061094 [Patent Document 2] JP 2017-123240 A [Patent Document 3] JP 2020-009744 A [Patent Document 4] Patent Publication No. 2021-022549 [Patent Document 5] Patent Publication No. 2021-022560 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem that the present invention aims to solve is to provide a solid oxide electrochemical cell stack that improves the reactivity of the hydrogen electrode, which is the main reaction in SOC, and makes it possible to increase the strength of the cell by suppressing displacement such as bending of the cell due to the pressure difference between the electrodes while ensuring the supply and diffusion of gas to the electrodes. [Means for solving the problem]

[0008] The solid oxide electrochemical cell stack of the embodiment includes a flat-plate type first electrochemical cell having a hydrogen electrode, a solid oxide electrolyte layer, and an oxygen electrode, a flat-plate type second electrochemical cell having a hydrogen electrode, a solid oxide electrolyte layer, and an oxygen electrode and stacked with the first electrochemical cell, a separator that is gas impermeable and conductive, and is disposed between the first electrochemical cell and the second electrochemical cell so as to be electrically connected to the hydrogen electrode of the first electrochemical cell and the oxygen electrode of the second electrochemical cell, and and the separator, a second conductive member electrically connecting the oxygen electrode of the second electrochemical cell to the separator, and a support and insulating member arranged on the outer periphery of a stack of the first electrochemical cell, the first conductive member, the separator, the second conductive member, and the second electrochemical cell, supplying gas to the hydrogen electrode and the oxygen electrode of the first electrochemical cell and the second electrochemical cell, supporting a space for generating gas, and preventing electrical short circuiting in the stacking direction of the stack. In the solid oxide electrochemical cell stack of the embodiment, the second conductive member comprises a conductive porous member that maintains the supply and diffusion of gas to the oxygen electrode, and a conductive structural support member that suppresses mechanical displacement of the first electrochemical cell and the second electrochemical cell. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a first example of a solid oxide electrochemical cell stack according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a configuration of an electrochemical cell of the solid oxide electrochemical cell stack shown in FIG. [Diagram 3] FIG. 2 is a cross-sectional view showing a second example of a solid oxide electrochemical cell stack according to an embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing a third example of a solid oxide electrochemical cell stack according to an embodiment. [Diagram 5] FIG. 2 is a plan view showing the gas flow in the solid oxide electrochemical cell stack shown in FIG. [Figure 6]2 is a plan view illustrating a first arrangement of electrically conductive structural support members in the solid oxide electrochemical cell stack shown in FIG. 1. [Figure 7] 2 is a plan view showing a second arrangement of electrically conductive structural support members in the solid oxide electrochemical cell stack shown in FIG. 1. FIG. [Figure 8] 2 is a plan view illustrating a third arrangement of electrically conductive structural support members in the solid oxide electrochemical cell stack illustrated in FIG. 1. [Figure 9] 1. FIG. 4 is a plan view illustrating a fourth arrangement of electrically conductive structural support members in the solid oxide electrochemical cell stack shown in FIG. [Figure 10] FIG. 11 is a cross-sectional view showing an exploded structure of a fourth example of a solid oxide electrochemical cell stack according to an embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a fifth example of a solid oxide electrochemical cell stack according to an embodiment. [Figure 12] FIG. 11 is a cross-sectional view showing a sixth example of a solid oxide electrochemical cell stack according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the solid oxide electrochemical cell of the embodiment will be described with reference to the drawings. In each embodiment shown below, substantially the same components are given the same reference numerals, and the description thereof may be omitted. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each part, etc. may differ from the actual ones. In the following description, the symbol "~" indicates a range between the upper limit value and the lower limit value of each numerical value. In this case, each numerical range includes the upper limit value and the lower limit value.

[0011] (First embodiment) Fig. 1 is a cross-sectional view showing a solid oxide electrochemical cell stack of the first embodiment. The solid oxide electrochemical cell stack 10 shown in Fig. 1 has a structure in which a first electrochemical cell structure 11A and a second electrochemical cell structure 11B are stacked with a separator 12 (a first separator 12A and a second separator 12B) interposed therebetween. The first electrochemical cell structure 11A and the second electrochemical cell structure 11B include a first electrochemical cell 13A and a second electrochemical cell 13B housed in recesses provided in the centers of the first separator 12A and the second separator 12B, respectively.

[0012] 1 shows a structure in which a first electrochemical cell structure 11A and a second electrochemical cell structure 11B are stacked, but the number of electrochemical cell structures 11 stacked is not particularly limited, and a structure in which three or more electrochemical cell structures 11 are stacked may be used. When three or more electrochemical cell structures 11 are stacked, a separator 12 is disposed between two adjacent electrochemical cells 13A, 13B, and the electrodes of each electrochemical cell 13A, 13B are electrically connected by the separator 12 (separator 12A, separator 12B). For the separator 12, a ferritic stainless steel such as SUS430, which has a thermal expansion coefficient close to that of the electrochemical cells 13A, 13B, is used.

[0013] The first electrochemical cell 13A and the second electrochemical cell 13B have the same configuration. As shown in Fig. 2, each of the first and second electrochemical cells 13A and 13B has a first electrode functioning as a hydrogen electrode 14, a second electrode functioning as an oxygen electrode 15, and a solid oxide electrolyte layer 16 disposed between these electrodes 14 and 15. The hydrogen electrode 14 has a hydrogen electrode active layer 141 disposed so as to be in contact with the solid oxide electrolyte layer 16, and a hydrogen electrode support layer 142 laminated with the hydrogen electrode active layer 141 and functioning as a support layer of the cell structure. A reaction prevention layer or the like may be disposed between the solid oxide electrolyte layer 16 and the oxygen electrode 15.

[0014] The hydrogen electrode 14 and the oxygen electrode 15 as the first and second electrodes are each formed of a porous electrical conductor. The hydrogen electrode 14 is formed by disposing a porous hydrogen electrode active layer 141 on a porous hydrogen electrode support layer 142. The solid oxide electrolyte layer 16 is made of, for example, a dense solid oxide electrolyte, and is an ion conductor that does not conduct electricity. The hydrogen electrode 14 and the oxygen electrode 15 having the hydrogen electrode active layer 141 and the hydrogen electrode support layer 142 are each formed of a gas-permeable electrical conductor such as a porous metal sintered body, a metal mesh body, or a metal net-like body so as not to block the flow of the supplied gas and the generated gas. This maintains the reaction at the hydrogen electrode 14 and the oxygen electrode 15, and allows the supplied gas and the generated gas to flow efficiently.

[0015] The hydrogen electrodes 14 and the separators 12 of the first electrochemical cell 13A and the second electrochemical cell 13B are electrically connected by the first conductive member 17 (first conductive members 17A, 17B) on the hydrogen electrode side. The oxygen electrodes 15 and the separators 12 of the first electrochemical cell 13A and the second electrochemical cell 13B are electrically connected by the second conductive member 18 (second conductive members 18A, 18B) on the oxygen electrode side. For the first conductive member 17 (first conductive members 17A, 17B) and the second conductive member 18 (second conductive members 18A, 18B), it is desirable to use a material that maintains conductivity in the atmosphere of each electrode under the operating conditions (600 to 900°C) and does not cause a chemical reaction with the electrodes or separator surfaces in contact with the first conductive member 17 and does not hinder the battery reaction. For example, nickel (Ni) or the like can be applied to the first conductive member 17 on the hydrogen electrode side, and silver (Ag) or the like can be applied to the second conductive member 18 on the oxygen electrode side. The first and second conductive members 17, 18 ensure electrical contact, via the separator 12, between the electrodes of the unit cells 13 that are in contact with each other due to stacking.

[0016] 1 shows only the structure in which the first electrochemical cell 13A and the second electrochemical cell 13B are stacked, and therefore shows the first conductive member 17A arranged between the hydrogen electrode (14) and the separator 12A of the first electrochemical cell 13A, and the first conductive member 17B arranged between the hydrogen electrode (14) and the separator 12B of the second electrochemical cell 13B. As for the second conductive members 18A and 18B on the oxygen electrode side, only the second conductive member 18B arranged between the oxygen electrode (15) and the separator 12A of the second electrochemical cell 13B is shown. In an actual device configuration, other electrochemical cells and separators are arranged on the second conductive member 18A, and therefore the second conductive member 18A is arranged between such a separator and the oxygen electrode (15) of the first electrochemical cell 13A.

[0017] At the frame-like ends of the separators 12A and 12B around the first and second electrochemical cells 13A and 13B, a support and insulating member 19 is arranged to maintain a space for supplying gas to the oxygen electrode 15 and discharging gas generated at the oxygen electrode 15, to prevent cell damage due to overtightening of the stack 10, and to prevent electrical short circuits in the stacking direction of the cells 13A and 13B. A gas seal layer 20 is arranged on the surface of the support and insulating member 19 between each metal member and insulating member. The gas seal layer 20 is made of glass or the like. By arranging such a gas seal layer 20, gas leakage (out leakage) to the outside of the stack at the end of the cell stack 10 is suppressed.

[0018] FIG. 1 shows a flat electrochemical cell 13. Here, the flat electrochemical cell 13 is assumed to be a square hydrogen electrode-supported cell, but the shape and specifications of the flat cell in actual operation are not particularly limited. For example, the shape may be square, rectangular, circular, etc., and the support type may be an electrode-supported type, an electrolyte-supported type, or a type supported by a support such as a metal. The gas to be supplied is selected according to the type of electrochemical cell 13. For example, when the electrochemical cell 13 is operated as a fuel cell, a gas mainly composed of hydrogen, a gas obtained by reforming a hydrocarbon fuel, ammonia, etc. is supplied to the hydrogen electrode 14 side, and a gas containing oxygen is supplied to the oxygen electrode 15 side. When used for steam electrolysis, a gas containing H2O such as water vapor is introduced to the hydrogen electrode 14 side, and air or the like is supplied to the oxygen electrode side for purging, or may not be supplied. A current is supplied to the cell stack 10 in the case of an electrolysis reaction, or a current is taken out in the case of a fuel cell reaction, via bus bars (current supply terminals / not shown) provided at the top and bottom.

[0019] In an electrochemical cell stack 10 in which flat plate-type first electrochemical cell 13A and second electrochemical cell 13B are stacked, it is necessary to ensure electrical contact between the electrode parts of the mutually contacting unit cells 13, and in the portion supporting the entire structure of the cell stack 10, it is necessary to maintain a space for gas supply to the oxygen electrode 15 / hydrogen electrode 14 and a space for gas generation, and to prevent cell damage due to over-tightening. Furthermore, in the portion supporting the entire structure of the cell stack 10, it is necessary to provide insulation to prevent electrical shorts between adjacent cells 13 in the stacking direction, particularly between the upper and lower fastening plates.

[0020] Furthermore, for each unit cell 13, it is necessary to prevent gas leakage (out-leak) from the end of the stack and gas leakage (cross-leak) between the oxygen electrode and the hydrogen electrode at the interface at the end of each cell 13, and also to suppress cracks and breakage due to distortion of the flat cell when a pressure difference occurs between the two electrodes. For example, in the flat cell stack 10 having the unit structure of Figures 1 and 2, when the gas pressure supplied to the hydrogen electrode side becomes high, the center of the flat unit cell 13 fixed at the end warps toward the oxygen electrode side, which makes the unit cell 13 prone to cracking. This tendency becomes more pronounced as the area of ​​the unit cell 13 becomes larger and the thickness of the unit cell 13 becomes thinner.

[0021] For this reason, the second conductive member 18 (18A, 18B) on the oxygen electrode side of the electrochemical cell 13 is required to have high strength while maintaining electrical conductivity, gas diffusibility, etc. Therefore, in the electrochemical cell stack 10 of the embodiment, the second conductive member 18 on the oxygen electrode side is composed of a composite member of a conductive porous member 21 that maintains the supply and diffusion of gas to the oxygen electrode 15, and a conductive structural support member 22 that suppresses mechanical displacement of the first electrochemical cell 13A and the second electrochemical cell 13B. This makes it possible to suppress mechanical displacement such as bending of the cells 13A and 13B due to the pressure difference between the electrodes while ensuring the supply and diffusibility of gas to the oxygen electrode 15. Therefore, it is possible to maintain the electrochemical reaction by the electrochemical cell 13, such as the fuel cell reaction of hydrogen and oxygen and the electrolytic reaction of H2O (steam electrolytic reaction), and further to maintain the dischargeability of the generated gas, while suppressing the occurrence of distortion and deformation of the flat electrochemical cell 13 due to the pressure difference between the two electrodes and the associated cracks and breakage, thereby improving the reliability of the electrochemical cell 13.

[0022] Metals such as silver (Ag) and carbon can be used for the conductive porous member 21 and the conductive structural support member 22. A conductive porous base material such as a porous metal sintered body, a metal mesh body, or a metal net-like body is used for the conductive porous member 21. A metal member having a solid structure capable of maintaining structural strength is used for the conductive structural support member 22. In FIG. 1, the conductive structural support member 22 is inserted into a hole provided in the conductive porous member 21 to form a composite, and the conductive porous member 21 and the conductive structural support member 22 are arranged so as to be alternately positioned. The structural support member 22 preferably has a Young's modulus equal to or greater than the base material rigidity of the flat cell 13 (before reduction: 70 GPa, after reduction: 30 GPa), for example, a Young's modulus of 70 GPa or more. This allows the structure to be maintained by sufficiently suppressing structural changes in the current collector when the flat cell 13 is displaced.

[0023] The structure of the second conductive member 18 (18A, 18B) is not limited to the above-mentioned structure. For example, as shown in FIG. 3, the conductive porous member 21 and the conductive structural support member 22 may be integrated and both sides may be flat. Alternatively, as described in the following embodiment, the conductive porous member 21 and the conductive structural support member 22 may be formed separately into a plate shape and then stacked to be used as an integrated member. Furthermore, as shown in FIG. 4, the conductive porous member 21 and the conductive structural support member 22 may be formed separately into a state in which a plurality of protrusions are formed on a flat plate, and then these protrusions may be combined and stacked to be used as an integrated member. In the second conductive member 18 described above, the thickness of the conductive porous member 21 in contact with the oxygen electrode 15 is preferably 0.05 mm or more. This makes it possible to ensure gas diffusion while suppressing an increase in contact resistance over the entire surface of the oxygen electrode 16. Therefore, the reaction can be efficiently carried out over the entire surface of the oxygen electrode 16.

[0024] 1, when a composite member is used by inserting a conductive structural support member 22 into a hole provided in a conductive porous member 21, the portion of the conductive structural support member 22 protruding from the conductive porous member 21 is present in the flow paths of the supply gas and the exhaust gas. As shown in FIG. 5, for example, the flow of gas in the electrochemical cell stack 10 is configured such that a gas supply hole 24 and a gas exhaust hole 25 on the hydrogen electrode 14 side and a gas supply hole 26 and a gas exhaust hole 27 on the oxygen electrode 15 side are provided in the separator 12 (12A, 12B...) around a stack 23 of a plurality of electrochemical cells 13 (13A, 13B...), so that gas is supplied parallel to the surfaces of the plurality of electrochemical cells 13 and generated gas is exhausted.

[0025] When a composite member of the conductive porous member 21 and the conductive structural support member 22 shown in Fig. 1 is used, the arrangement shape of the conductive structural support member 22 on the plane of the separator 12 is not particularly limited, and may be, for example, linear support members 22 arranged in parallel or in a lattice as shown in Fig. 6, linear support members 22 arranged in a cross shape or at an angle as shown in Fig. 7, or round or square dot-shaped support members 22 arranged at equal intervals as shown in Fig. 8 and Fig. 9. However, it is preferable to arrange the conductive structural support member 22 so as not to obstruct the flow of the supply gas and generated gas to the oxygen electrode 15.

[0026] When using the conductive porous member 21 and the conductive structural support member 22 having a plurality of protrusions formed on a flat plate as shown in FIG. 4, the conductive structural support member 22 may be integrated with the separator 12 arranged opposite the second conductive member 18 as shown in FIG. 10. Similarly, the conductive porous member 21 may be integrated with the electrochemical cell 13 (specifically, the oxygen electrode). By applying such a configuration, it is possible to eliminate the labor required for stacking a plurality of electrochemical cells 13 to form a stack, and to improve the manufacturability of the cell stack. The structural support member 22 may be integrated with the separator 12 by welding, cutting, or the like, or may be processed by pressing or the like.

[0027] In addition to the conductive porous member 21 and the conductive structural support member 22, the second conductive member 18 may include a conductive elastic structural member 28 as shown in FIG. 11. The second conductive member 18 shown in FIG. 11 has a configuration in which an elastic structural member 28 is arranged on a laminate of the porous member 21 and the structural support member 22, and the elastic structural member 28 is in contact with the separator 12. Examples of structures that provide elasticity include a leaf spring structure or a wave spring structure made of a metal plate material that has oxidation resistance and electrical conductivity in the oxygen electrode atmosphere during operation. The elasticity that the spring structure of the elastic structural member 28 should have is preferably elasticity equivalent to a spring constant of 5 kg / cm or more in the operating environment (corresponding to the elasticity of urethane at room temperature). This makes it possible to sufficiently reduce the contact resistance between the separator and the oxygen electrode of the flat cell 13 without damaging the flat cell 13 through the separator (current collector) 12.

[0028] Furthermore, the shapes of the conductive porous member 21 and the conductive structural support member 22 in the second conductive member 18 are not limited to the shape in which protrusions are combined in the planar direction as shown in Fig. 1. For example, as shown in Fig. 12, a structure in which a flat conductive porous member 21 and a flat conductive structural support member 22 are laminated may be provided. With such a second conductive member 18, it is possible to maintain the electrochemical reaction by the electrochemical cell 13, such as a fuel cell reaction or an electrolytic reaction of H2O, and further to maintain the dischargeability of the generated gas, while suppressing the occurrence of distortion or deformation of the flat electrochemical cell 13 due to the pressure difference between the two electrodes and the associated cracks or breakage, thereby improving the reliability of the electrochemical cell 13.

[0029] The configurations of the above-mentioned embodiments can be applied in combination with each other, and some of them can be replaced. Although several embodiments of the present invention have been described here, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0030] 10...solid oxide electrochemical cell stack, 12, 12A, 12B...separators, 13A...first electrochemical cell, 13B...second electrochemical cell, 14...hydrogen electrode, 15...oxygen electrode, 16...solid oxide electrolyte layer, 17, 17A, 17B...first conductive member, 18, 18A, 18B...second conductive member, 19...support and insulating member, 20...gas seal layer, 21...conductive porous member, 22...conductive structural support member, 28...conductive elastic structural member.

Claims

1. a first electrochemical cell of a flat plate type including a hydrogen electrode, a solid oxide electrolyte layer, and an oxygen electrode; a second electrochemical cell of a flat plate type including a hydrogen electrode, a solid oxide electrolyte layer, and an oxygen electrode, and stacked on the first electrochemical cell; a separator that is gas impermeable and electrically conductive, and that is disposed between the first electrochemical cell and the second electrochemical cell so as to be electrically connected to the hydrogen electrode of the first electrochemical cell and the oxygen electrode of the second electrochemical cell; a first conductive member electrically connecting the hydrogen electrode and the separator of the first electrochemical cell; a second conductive member electrically connecting the oxygen electrode and the separator of the second electrochemical cell; a support and insulating member disposed on an outer periphery of a stack of the first electrochemical cell, the first conductive member, the separator, the second conductive member, and the second electrochemical cell, the support and insulating member supplying gas to the hydrogen electrodes and the oxygen electrodes of the first electrochemical cell and the second electrochemical cell, supporting a space for generating gas, and preventing an electrical short circuit in a stacking direction of the stack, the second conductive member comprises a conductive porous member that maintains the supply and diffusion of gas to the oxygen electrode, and a conductive structural support member that suppresses mechanical displacement of the first electrochemical cell and the second electrochemical cell.

2. 2. The solid oxide electrochemical cell stack of claim 1, wherein the electrically conductive structural support member has a solid structure, and the electrically conductive porous member comprises a porous sintered body, a mesh body, or a reticulated body.

3. 10. The solid oxide electrochemical cell stack of claim 1, wherein the electrically conductive porous member has a thickness of 0.05 mm or greater.

4. 10. The solid oxide electrochemical cell stack of claim 1, wherein said electrically conductive structural support members have a Young's modulus of 70 GPa or greater.

5. 10. The solid oxide electrochemical cell stack of claim 1, wherein the second conductive member further comprises a conductive resilient structural member disposed on a composite of the conductive porous member and the conductive structural support member.

6. 10. The solid oxide electrochemical cell stack of claim 1, wherein the conductive resilient structural member has a spring constant of 5 kg / cm or greater in an operating environment.

7. The electrochemical cell stack according to claim 1 , wherein the second conductive member has a structure in which the conductive porous members and the conductive structural support members are alternately arranged in a planar direction.

8. The electrochemical cell stack according to claim 1 , wherein the second conductive member has a structure in which the conductive porous member and the conductive structural support member are stacked in a thickness direction.

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