Electrochemical reaction cell stack

Abstract

To suppress occurrence of a crack and a bonding failure of a seal member without increasing the size of a stack.SOLUTION: An electrochemical reaction cell stack comprises a first bonding object member, a second bonding object member, and a seal member for bonding the first bonding object member and the second bonding object member. The seal member comprises: a first glass seal made of glass and bonded to the first bonding object member; a second glass seal made of glass and bonded to the second bonding object member; and an intermediate seal made of insulating ceramics and disposed between the first glass seal and the second glass seal. Between a first virtual surface including a surface bonding the first bonding object member and the first glass seal and a second virtual surface including a surface bonding the second bonding object member and the second glass seal, a conductive member electrically connected to the second bonding object member or part of the second bonding object member is arranged.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The technology disclosed herein relates to electrochemical reaction cell stacks. [Background technology]

[0002] Solid oxide fuel cells (hereinafter referred to as "SOFCs"), which have an electrolyte layer containing solid oxide, are known as one type of fuel cell that generates electricity using the electrochemical reaction between hydrogen and oxygen. SOFCs are generally used in the form of a fuel cell stack, in which multiple constituent units (electrochemical reaction units) are arranged in a predetermined direction.

[0003] A sealing member is used to seal between two components in a fuel cell stack. The sealing member may include first and second glass frit layers and an insulating layer disposed between the first and second frit layers (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2010-511996 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned SOFC, it is required to reduce the occurrence of poor bonding and cracks in the sealing members without increasing the size of the stack.

[0006] These issues are also common to electrolysis cell stacks that include multiple electrolysis cell units, which are constituent elements of solid oxide electrolysis cells (hereinafter referred to as "SOECs") that generate hydrogen using the electrolysis reaction of water. Furthermore, these issues are not limited to SOFCs and SOECs, but are also common to other types of electrochemical reaction cell stacks. [Means for solving the problem]

[0007] The technology disclosed in this specification can be realized, for example, in the following forms. (1) The electrochemical reaction cell stack disclosed in this specification comprises a first member to be joined, a second member to be joined, and a sealing member that joins the first member to be joined and the second member to be joined, wherein the sealing member comprises a first glass seal made of glass that is joined to the first member to be joined, a second glass seal made of glass that is joined to the second member to be joined, and an intermediate seal made of insulating ceramic that is arranged between the first glass seal and the second glass seal, and a conductive member electrically connected to the second member to be joined or a part of the second member to be joined is arranged between a first imaginary plane that includes the joining surface between the first member to be joined and the first glass seal and a second imaginary plane that includes the joining surface between the second member to be joined and the second glass seal.

[0008] According to the above configuration, a large space for disposing the seal member between the first and second members to be joined can be secured without increasing the size of the stack, thereby reducing the occurrence of poor joining or cracks in the seal member.

[0009] (2) In the electrochemical reaction cell stack described in (1) above, the conductive member may be arranged between the first imaginary surface and the second imaginary surface, the conductive member may have a conductive sealing hole, and at least a portion of the sealing member may be arranged inside the conductive sealing hole.

[0010] According to this configuration, a space for disposing the seal member can be easily secured between the first member to be joined and the second member to be joined.

[0011] (3) In the electrochemical reaction cell stack described in (2) above, a gap may be present between the conductive member and the intermediate seal.

[0012] With this configuration, the conductive member and the intermediate seal are not in contact with each other, which prevents leakage current from flowing to the first or second glass seal via the intermediate seal, thereby reducing the occurrence of peeling of the seal member from the second end plate.

[0013] (4) The electrochemical reaction cell stack described in (2) or (3) above may further include an insulating member arranged between the conductive member and the first joining target member, the insulating member having an insulating seal hole, a portion of the seal member being arranged inside the insulating seal hole, and the distance between the intermediate seal and the insulating member may be smaller than the distance between the intermediate seal and the conductive member.

[0014] With this configuration, the insulating member prevents contact between the conductive member and the intermediate seal, preventing leakage current from flowing to the first or second glass seal via the intermediate seal, thereby reducing the occurrence of peeling of the seal member from the second end plate.

[0015] (5) In the electrochemical reaction cell stack described in (1) above, the second member to be joined may have an opposing surface facing the first member to be joined and a recessed portion disposed on the opposing surface, and at least a portion of the sealing member may be disposed inside the recessed portion.

[0016] According to this configuration, a space for disposing the seal member can be easily secured between the first member to be joined and the second member to be joined.

[0017] (6) In the electrochemical reaction cell stack described in (5) above, a gap may be present between the second joining target member and the intermediate seal.

[0018] With this configuration, the second joining target component and the intermediate seal are not in contact with each other, which prevents leakage current from flowing to the first or second glass seal via the intermediate seal, thereby reducing the occurrence of peeling of the seal member from the second end plate.

[0019] (7) The electrochemical reaction cell stack described in (5) or (6) above may further include an insulating member arranged between the first member to be joined and the second member to be joined, the insulating member having an insulating seal hole, a portion of the seal member being arranged inside the insulating seal hole, and the distance between the intermediate seal and the insulating member may be smaller than the distance between the intermediate seal and the second member to be joined.

[0020] With this configuration, the insulating member prevents contact between the second joining target component and the intermediate seal, thereby preventing leakage current from flowing to the first or second glass seal via the intermediate seal, thereby reducing the occurrence of peeling of the seal member from the second end plate.

[0021] The technology disclosed in this specification can be realized in various forms, for example, in the form of an electrochemical reaction cell stack and a manufacturing method thereof. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing the external configuration of a fuel cell stack according to an embodiment; [Figure 2] FIG. 2 is a cross-sectional view of the fuel cell stack according to the embodiment taken along line II-II in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view of the fuel cell stack according to the embodiment taken along line III-III in FIG. 1. [Figure 4] 2 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the embodiment, taken along the same line as in FIG. 1; [Figure 5]3 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the embodiment, taken along the same line as line III-III in FIG. 1; [Figure 6] FIG. 3 is an enlarged partial cross-sectional view showing the area within the frame F1 in FIG. 2; [Figure 7] FIG. 7 is an enlarged partial cross-sectional view showing the area within the frame F2 in FIG. 6; [Figure 8] 8 is a cross-sectional view showing the fuel cell stack of the embodiment taken along line VIII-VIII in FIG. 6. [Figure 9] FIG. 10 is a partially enlarged cross-sectional view of a fuel cell stack according to a modified example; DETAILED DESCRIPTION OF THE INVENTION

[0023] A. First embodiment: The first embodiment will be described with reference to Figures 1 to 8. A fuel cell stack 10 (an example of an electrochemical reaction cell stack) of this embodiment is used in a solid oxide fuel cell having an electrolyte layer 112 containing a solid oxide.

[0024] (Overall configuration of fuel cell stack 10) 1 to 3, the fuel cell stack 10 includes a power generation block 100, an end separator 230, a first plate 232, a second plate 260 (an example of an insulating member), a third plate 610, a base plate 600 (an example of a conductive member), a first terminal plate 240, a second terminal plate 250, an insulating section 220, a first end plate 210, a second end plate 270 (an example of a first joining target member), and four gas passage members 280. The first end plate 210, the insulating section 220, the end separator 230, the first terminal plate 240, the power generation block 100, the second terminal plate 250, the third plate 610, the base plate 600, the second plate 260, and the second end plate 270 have rectangular outer shapes of approximately the same size and are arranged in a stacked manner in this order in a predetermined arrangement direction (the vertical direction in FIG. 2).

[0025] As shown in Fig. 1, the fuel cell stack 10 has bolt holes BH near each of the four corners, penetrating from the first end plate 210 to the second end plate 270. A bolt B is inserted into each bolt hole BH. A nut N is screwed onto both ends of each bolt B. These bolts B and nuts N fasten the members from the first end plate 210 to the second end plate 270 together. As shown in Figs. 2 and 3, the first plate 232 is supported by the terminal separator 230, and the four gas passage members 280 are connected to the second end plate 270.

[0026] As shown in Figures 2 and 3, the power generation block 100 is composed of multiple (seven in this embodiment) electrochemical reaction units 100U (hereinafter sometimes abbreviated as "reaction units 100U") arranged in a predetermined arrangement direction (vertical direction in Figure 2).

[0027] (Overall configuration of 100U electrochemical reaction units) 4 and 5, the electrochemical reaction unit 100U includes a single cell 110, a single cell separator 120, an air electrode frame 130, an anode frame 140, an anode current collecting member 144, two interconnectors 190, and two IC separators 180. One IC separator 180, the air electrode frame 130, the single cell separator 120, the anode frame 140, and the other IC separator 180 are stacked in this order. The single cell 110 is supported by the single cell separator 120, and the two interconnectors 190 are supported by the two IC separators 180, respectively, with the anode current collecting member 144 being disposed between the single cell 110 and the interconnectors 190. The IC separator 180 and the interconnector 190 are shared by two adjacent reaction units 100U. In the following description, when describing the reaction unit 100U at one end (the lower end in FIG. 2) closest to the second end plate 270 among the multiple reaction units 100U in order to distinguish it from the others, it will be referred to as the "reaction unit 100UN." Furthermore, when describing the IC separator 180 provided in this reaction unit 100UN and arranged in the outermost layer of the power generation block 100 in order to distinguish it from the others, it will be referred to as the "IC separator 180E." The IC separator 180E is an example of a second member to be joined.

[0028] (single cell 110) The unit cell 110 includes an electrolyte layer 112, a cathode 114, and an anode 116. As shown in Figures 4 and 5, the cathode 114, the electrolyte layer 112, and the anode 116 are stacked in this order, with a reaction prevention layer 118 interposed between the electrolyte layer 112 and the cathode 114. The unit cell 110 of this embodiment is an anode-supported unit cell in which the anode 116 supports the other layers (electrolyte layer 112, cathode 114, and reaction prevention layer 118) that make up the unit cell 110.

[0029] The electrolyte layer 112 is a rectangular, flat member having one surface (the upper surface in FIGS. 4 and 5) on which the air electrode 114 is disposed and another surface (the lower surface in FIGS. 4 and 5) parallel to the first surface on which the anode 116 is disposed. The electrolyte layer 112 is a layer containing a solid oxide (e.g., YSZ (yttria-stabilized zirconia)). The cathode 114 is a layer having a rectangular shape smaller than that of the electrolyte layer 112 and containing, for example, a perovskite-type oxide (e.g., LSCF (lanthanum strontium cobalt iron oxide)). The anode 116 is a layer having a rectangular shape and approximately the same size as the electrolyte layer 112 and containing, for example, Ni (nickel), a cermet made of Ni and ceramic particles, a Ni-based alloy, or the like. The reaction prevention layer 118 is a layer having a rectangular shape and approximately the same size as the air electrode 114 and containing, for example, GDC (gadolinium-doped ceria). The reaction prevention layer 118 has the function of preventing elements (e.g., Sr) diffused from the air electrode 114 from reacting with elements (e.g., Zr) contained in the electrolyte layer 112 to produce a highly resistive substance (e.g., SrZrO3).

[0030] (Single cell separator 120) As shown in FIGS. 4 and 5, the single cell separator 120 is a rectangular frame-shaped member having a substantially rectangular through-hole 121 near the center. The single cell separator 120 is electrically conductive and is made of a metal such as ferritic stainless steel. The thickness of the single cell separator 120 is, for example, 0.05 mm or more and 0.2 mm or less. The peripheral portion of the through-hole 121 in the single cell separator 120 is joined to the peripheral portion of one surface of the electrolyte layer 112 (the surface on which the air electrode 114 is disposed: the upper surface in FIGS. 4 and 5) by a joint 124. The joint 124 is made of, for example, a brazing material (Ag brazing).

[0031] (Air electrode frame 130) 4 and 5, the cathode frame 130 is a rectangular frame-like member having a substantially rectangular through-hole 131 near the center, and is made of, for example, insulating ceramics (mica, etc.). The thickness of the cathode frame 130 is, for example, 0.5 mm or more and 5 mm or less.

[0032] (fuel electrode frame 140) 5, the fuel electrode frame 140 is a rectangular frame-like member having a substantially rectangular through-hole 141 near the center. The fuel electrode frame 140 is electrically conductive and is made of a metal such as ferritic stainless steel.

[0033] (IC separator 180) 4 and 5, IC separator 180 is a rectangular frame-shaped member having a through-hole 181 near the center. IC separator 180 is conductive and is made of a metal such as ferritic stainless steel. The thickness of IC separator 180 is, for example, 0.05 mm or more and 0.2 mm or less.

[0034] (Interconnector 190 and anode current collecting member 144) As shown in FIGS. 4 and 5 , the interconnector 190 includes a rectangular flat plate portion 191, a plurality of plate-shaped air electrode current collectors 192 protruding from one surface of the flat plate portion 191 toward the air electrode 114, and a coating layer 193. The flat plate portion 191 and the air electrode current collector 192 are electrically conductive and formed of a metal such as ferritic stainless steel. The coating layer 193 is electrically conductive and formed of a spinel-type oxide, for example. The coating layer 193 is disposed so as to cover the surface of the air electrode current collector 192 and the surface of the flat plate portion 191 on which the air electrode current collector 192 is disposed. The flat plate portion 191 is joined to the periphery of the through-hole 181 in the IC separator 180, for example, by welding.

[0035] The anode current collecting member 144 is a member that connects the interconnector 190 and the anode 116, and is formed of a conductive material such as nickel, a nickel alloy, or stainless steel. As shown in Figures 4 and 5, the anode current collecting member 144 has an interconnector facing portion 146, an electrode facing portion 145 that is parallel to the interconnector facing portion 146, and a connecting portion 147 that connects the electrode facing portion 145 and the interconnector facing portion 146, and has an overall U-shape. The electrode facing portion 145 is in contact with the anode 116, and the interconnector facing portion 146 is in contact with a flat portion 191 of the interconnector 190.

[0036] As described above, the interconnector 190 is shared by two adjacent reaction units 100U. More specifically, as shown in Figures 4 and 5, the air electrode current collecting part 192 is joined to the air electrode 114 of the unit cell 110 provided in one of the two adjacent reaction units 100U via a conductive bonding material 196 made of, for example, a spinel-type oxide, and is thereby electrically connected to the air electrode 114. The flat plate part 191 is electrically connected to the anode 116 of the unit cell 110 provided in the other of the two adjacent reaction units 100U via an anode current collecting member 144. This ensures electrical continuity between the two adjacent reaction units 100U.

[0037] A spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146. This allows the anode current collecting member 144 to follow deformation of the reaction unit 100U due to temperature cycles and fluctuations in reactant gas pressure, and good electrical connection between the anode 116 and the interconnector 190 (or second terminal plate 250) via the anode current collecting member 144 is maintained.

[0038] (Air chamber 313 and fuel chamber 323) 4 and 5, the space partitioned by the single cell separator 120, single cell 110, air electrode frame 130, IC separator 180, and interconnector 190 faces the air electrode 114 and serves as an air chamber 313 through which oxidant gas OG flows. The air electrode frame 130 partitions the entire periphery of the air chamber 313 from the external space and seals the gap between the single cell separator 120 and the IC separator 180, preventing gas from leaking from the air chamber 313 to the external space.

[0039] The space partitioned by the single cell separator 120, the single cell 110, the fuel electrode frame 140, the IC separator 180, and the interconnector 190 faces the fuel electrode 116 and forms a fuel chamber 323 through which fuel gas FG flows. The fuel electrode frame 140 partitions the entire periphery of the fuel chamber 323 from the external space, and seals the gap between the single cell separator 120 and the IC separator 180, thereby preventing gas from leaking from the fuel chamber 323 to the external space.

[0040] The single cell separator 120 separates the air chamber 313 and the fuel chamber 323, thereby preventing gas leakage (cross leakage) from the air electrode 114 side to the fuel electrode 116 side or from the fuel electrode 116 side to the air electrode 114 side around the single cell 110. In addition, the IC separator 180 and the interconnector 190 prevent gas leakage between adjacent reaction units 100U.

[0041] (First end plate 210) The first end plate 210 is a member formed by pressing (bending) a single plate-like member. The first end plate 210 is formed of a metal such as ferritic stainless steel. The thickness of the first end plate 210 is, for example, 0.5 mm or more and 3 mm or less. As shown in FIGS. 1 to 3 , the first end plate 210 includes a rectangular, frame-like flat portion 211 having a through-hole 212 near the center, and an outer convex portion 213 and an inner convex portion 214 that protrude from the flat portion 211 in the direction opposite the insulating portion 220 (upward in FIG. 2 ). The flat portion 211 has holes that form the bolt holes BH described above. The outer convex portion 213 protrudes from the outer periphery of the flat portion 211. The outer convex portion 213 is disposed around the entire periphery of the flat portion 211. The inner convex portion 214 protrudes from the inner periphery of the flat portion 211. The inner convex portion 214 is disposed along the entire inner periphery of the flat portion 211 .

[0042] (insulating part 220) Insulating section 220 is a rectangular frame-shaped member with a through-hole near the center, and is made of an insulating material. As shown in Figures 2 and 3, insulating section 220 is sandwiched between first end plate 210 and end separator 230, thereby ensuring insulation between first end plate 210 and end separator 230.

[0043] (Terminal separator 230) 2 and 3, terminal separator 230 is a rectangular frame-shaped member having a through-hole 231 near the center. Terminal separator 230 is conductive and is made of a metal such as ferritic stainless steel.

[0044] (First Plate 232) The first plate 232 is a rectangular, flat member. The first plate 232 is electrically conductive and is made of a metal such as ferritic stainless steel. As shown in FIGS. 2 and 3 , the first plate 232 is joined to the peripheral portion of the through-hole 231 in the terminal separator 230 by, for example, welding. The terminal separator 230 and the first plate 232 separate the power generation block 100 from the external space of the fuel cell stack 10.

[0045] The first plate 232 is connected to an interconnector 190 provided in the reaction unit 100U located at the other end (the upper end in Figure 2) of the multiple reaction units 100U that make up the power generation block 100 via a connecting member having the same structure as the anode current collecting member 144, thereby electrically connecting this reaction unit 100U and the first plate 232.

[0046] (First terminal plate 240) As shown in FIGS. 2 and 3, the first terminal plate 240 is a rectangular frame-shaped member having a through-hole 241 near the center. The first terminal plate 240 is electrically conductive and is formed of a metal such as ferritic stainless steel. The thickness of the first terminal plate 240 is, for example, 0.2 mm or more and 3 mm or less. The first terminal plate 240 is electrically connected to the reaction unit 100U located at the other end (the upper end in FIG. 2) of the multiple reaction units 100U constituting the power generation block 100 via a first plate 232 and a terminal separator 230. One end (the right end in FIG. 2) of the first terminal plate 240 protrudes laterally from the power generation block 100, and this protruding portion functions as a positive output terminal for the fuel cell stack 10.

[0047] (2nd terminal plate 250) As shown in FIGS. 2 and 3, the second terminal plate 250 is a rectangular frame-shaped member having a through-hole 251 near the center. The second terminal plate 250 is electrically conductive and is made of a metal such as ferritic stainless steel. The thickness of the second terminal plate 250 is, for example, 0.2 mm or more and 3 mm or less. The second terminal plate 250 is disposed between the unit cell separator 120 and the IC separator 180E provided in the reaction unit 100UN, and is electrically connected to the unit cell 110 via the unit cell separator 120. One end of the second terminal plate 250 (the right end in FIG. 2) protrudes laterally from the power generation block 100, and this protruding portion functions as the negative output terminal of the fuel cell stack 10.

[0048] (Third Plate 610) 2 and 3, the third plate 610 is a rectangular frame-shaped member having a through-hole 611 near the center. The third plate 610 is made of an insulating material such as mica.

[0049] (Base plate 600) The base plate 600 is a rectangular, flat member. The base plate 600 is conductive and is made of a metal such as ferritic stainless steel. The base plate 600 is in contact with an interconnector 190 supported by an IC separator 180E, and is electrically connected to the reaction unit 100UN via this interconnector 190.

[0050] (Second plate 260) The second plate 260 is a rectangular flat plate member, and is made of an insulating material such as mica.

[0051] (Second end plate 270) The second end plate 270 is a member formed by pressing (bending) a single plate-like member. The second end plate 270 is formed of a metal such as ferritic stainless steel. The thickness of the second end plate 270 is, for example, 0.5 mm or more and 3 mm or less. As shown in FIGS. 2 and 3 , the second end plate 270 includes a rectangular, frame-like flat portion 271 having a through-hole 272 near the center, and an outer convex portion 273 and an inner convex portion 274 that protrude from the flat portion 271 in the direction opposite to the second terminal plate 250 (downward in FIG. 2 ). The outer convex portion 273 protrudes from the outer periphery of the flat portion 271. The outer convex portion 273 is disposed around the entire periphery of the flat portion 271. The inner convex portion 274 protrudes from the inner periphery of the flat portion 271. The inner convex portion 274 is disposed around the entire inner periphery of the flat portion 271.

[0052] As shown in FIGS. 2 and 3, the peripheral edge of the second plate 260 is sandwiched between the second end plate 270 and the base plate 600, thereby ensuring insulation between the base plate 600 and the second end plate 270.

[0053] (Manifolds 311, 312, 321, 322) 1 to 3, the fuel cell stack 10 has four holes that penetrate from the power generation block 100 to the second end plate 270. The four holes correspond to an oxidant gas supply manifold 311, an oxidant gas discharge manifold 312, a fuel gas supply manifold 321, and a fuel gas discharge manifold 322, respectively.

[0054] 2, the oxidant gas supply manifold 311 is a gas flow path that supplies the oxidant gas OG introduced from outside the fuel cell stack 10 to the air chamber 313 of each reaction unit 100U. The oxidant gas discharge manifold 312 is a gas flow path that discharges the oxidant off-gas OOG discharged from the air chamber 313 of each reaction unit 100U to the outside of the fuel cell stack 10. As the oxidant gas OG, for example, air is used.

[0055] 3, the fuel gas supply manifold 321 is a gas flow path that supplies fuel gas FG introduced from outside the fuel cell stack 10 to the fuel chambers 323 of each reaction unit 100U. The fuel gas discharge manifold 322 is a gas flow path that discharges fuel off-gas FOG discharged from the fuel chambers 323 of each reaction unit 100U to the outside of the fuel cell stack 10. As the fuel gas FG, for example, a hydrogen-rich gas obtained by reforming city gas is used.

[0056] The IC separator 180E has four manifold holes. The four manifold holes are holes that penetrate the second terminal plate 250 and are part of the manifolds 311, 312, 321, and 322, respectively. Of the four manifold holes provided in the IC separator 180E, the manifold hole that forms part of the oxidant gas supply manifold 311 will hereinafter be referred to as the "manifold hole 311H1" (see FIG. 6).

[0057] Second end plate 270 has four manifold holes. The four manifold holes are holes that penetrate second end plate 270 and are part of four manifolds 311, 312, 321, and 322. Hereinafter, of the four manifold holes provided in second end plate 270, the manifold hole that forms part of oxidant gas supply manifold 311 will be referred to as "manifold hole 311H2" (see FIG. 6).

[0058] (Gas passage member 280) As shown in FIGS. 1 to 3, each of the four gas passage members 280 includes a main body portion 281 and a flange portion 282. The main body portion 281 is cylindrical with both ends open. The flange portion 282 is provided so as to protrude outward from one end (the lower end in FIG. 2) of the main body portion 281. The flange portion 282 has a plurality of bolt holes 284. A bolt (not shown) for connecting the fuel cell stack 10 to an external device is inserted into each bolt hole 284.

[0059] The second end plate 270 has four holding tube portions 275 for connecting the gas passage member 280. As shown in FIG. 6, one of the four holding tube portions 275 is a cylindrical portion extending from the edge of the manifold hole 311H2 toward the opposite side from the power generation block 100 (downward in FIG. 6). One end (the upper end in FIG. 6) of the main body portion 281 is joined to the holding tube portion 275 by, for example, welding. The internal space of the main body portion 281 is in communication with the oxidant gas supply manifold 311. A gas pipe (not shown) for supplying or discharging gas is connected to each of the main body portions 281. The other three holding tube portions 275 are disposed at positions corresponding to the manifolds 312, 321, and 322, respectively, and are similarly connected to the gas passage member 280.

[0060] (Joining Structure Between IC Separator 180E and Second End Plate 270) The second end plate 270 is joined to the IC separator 180E via a seal member 500. More specifically, the peripheral portions of the four manifolds 311, 312, 321, and 322 on the flat surface portion 271 are each joined to the IC separator 180E via a seal member 500. Since the peripheral joining structures of the four manifolds 311, 312, 321, and 322 are identical to one another, the following describes the peripheral joining structure of the oxidant gas supply manifold 311, and omits a description of the other three.

[0061] As described above, the third plate 610, the base plate 600, and the second plate 260 are arranged between the IC separator 180E and the second end plate 270, stacked in this order.

[0062] 6, the second plate 260 has a second seal hole 261 (an example of an insulating seal hole) at a position corresponding to the oxidizing gas supply manifold 311. The second seal hole 261 is a hole slightly larger than the manifold holes 311H1 and 311H2 and passes through the second plate 260. The third plate 610 has a third seal hole 612 at a position corresponding to the oxidizing gas supply manifold 311. The third seal hole 612 is a hole of approximately the same size as the second seal hole 261 and passes through the third plate 610. The base plate 600 has a first seal hole 601 (an example of a conductive seal hole) at a position corresponding to the oxidizing gas supply manifold 311. The first seal hole 601 is a hole slightly larger than the second seal hole 261 and the third seal hole 612 and passes through the base plate 600. The first seal hole 601, the second seal hole 261, and the third seal hole 612 are arranged concentrically, and a seal member 500 is housed inside them.

[0063] As shown in FIG. 7, the seal member 500 includes a first glass seal 510, a second glass seal 520, and an intermediate seal 530, which are arranged in this order.

[0064] As shown in FIGS. 6-8, the first glass seal 510 is an annular member having a first through-hole 511. The first glass seal 510 is made of glass. The first glass seal 510 may be made of, for example, SiO2-B2O3-MgO-based glass. As shown in FIGS. 6 and 7, one surface of the first glass seal 510 is bonded to the second end plate 270, and the other surface is bonded to the intermediate seal 530.

[0065] The second glass seal 520 is an annular member having a second through-hole 521 and has substantially the same shape as the first glass seal 510. The second glass seal 520 is made of glass. The second glass seal 520 may be made of, for example, SiO2-B2O3-MgO-based glass. As shown in FIGS. 6 and 7, one surface of the second glass seal 520 is bonded to the IC separator 180E and the other surface is bonded to the intermediate seal 530.

[0066] As shown in FIGS. 6-8, the intermediate seal 530 is an annular member having a third through hole 531. The intermediate seal 530 is an insulating member. The material of the intermediate seal 530 may be any material having a higher electrical resistivity than the glass used for the first glass seal 510 and the second glass seal 520, such as insulating ceramics. More specifically, the intermediate seal 530 may be a ceramic containing magnesium oxide (MgO) or a ceramic containing magnesium oxide as its main component. In this specification, the term "main component" means that the component is contained in an amount of 90% by volume or more. In this embodiment, the intermediate seal 530 contains magnesium oxide in an amount of 90% by volume or more and also contains a sintering aid (e.g., CaO, SiO2, Al2O3), etc. The outer shape of the intermediate seal 530 is slightly larger than those of the first glass seal 510 and the second glass seal 520, and the third through hole 531 is slightly smaller than those of the first through hole 511 and the second through hole 512.

[0067] 6 and 7, the intermediate seal 530 is sandwiched between the first glass seal 510 and the second glass seal 520. The first glass seal 510, the second glass seal 520, and the intermediate seal 530 are concentrically arranged so that the first through hole 511, the second through hole 521, and the third through hole 531 are connected to each other. The peripheral edge of the intermediate seal 530 protrudes outward beyond the outer peripheries of the first glass seal 510 and the second glass seal 520. The three through holes 511, 521, and 531 are part of the oxidant gas supply manifold 311.

[0068] There is a gap between the base plate 600 and the intermediate seal 530. Furthermore, the distance between the intermediate seal 530 and the second plate 260 is smaller than the distance between the intermediate seal 530 and the base plate 600. Similarly, the distance between the intermediate seal 530 and the third plate 610 is smaller than the distance between the intermediate seal 530 and the base plate 600. More specifically, the distance D2 between the outer peripheral surface of the intermediate seal 530 and the inner peripheral surface of the second seal hole 261 is smaller than the distance D1 between the outer peripheral surface of the intermediate seal 530 and the inner peripheral surface of the first seal hole 601. Similarly, the distance D3 between the outer peripheral surface of the intermediate seal 530 and the inner peripheral surface of the third seal hole 612 is smaller than the distance D1 between the outer peripheral surface of the intermediate seal 530 and the inner peripheral surface of the first seal hole 601.

[0069] (Method of manufacturing fuel cell stack 10) An example of a method for manufacturing the fuel cell stack 10 having the above configuration will be described below.

[0070] The second plate 260, base plate 600, and third plate 610 are placed on top of the second end plate 270 in this order. The first glass seal 510, intermediate seal 530, and second glass seal 520 are placed inside the seal holes 261, 601, and 612 in this order. The IC separator 180E is placed on top of the third plate 610, and other components are then layered to assemble the fuel cell stack 10. The base plate 600 supports the components being layered from below. The assembled fuel cell stack 10 is heat-treated at a temperature higher than the operating temperature. The heat-treatment temperature is, for example, 850°C. This heat treatment bonds the IC separator 180E and intermediate seal 530 together with the first glass seal 510, and bonds the intermediate seal 530 and the second end plate 270 together with the second glass seal 520.

[0071] (Operation of fuel cell stack 10) As shown in FIGS. 2 and 4, the oxidizing gas OG is supplied from the oxidizing gas supply manifold 311 to the air chamber 313 via the gas passage member 280.

[0072] As shown in FIGS. 3 and 5, the fuel gas FG is supplied from the fuel gas supply manifold 321 to the fuel chamber 323 via the gas passage member 280.

[0073] When an oxidant gas OG is supplied to the air chamber 313 of each reaction unit 100U and a fuel gas FG is supplied to the fuel chamber 323, power is generated in the single cell 110 by an electrochemical reaction between the oxidant gas OG and the fuel gas FG. This power generation reaction is exothermic. As described above, the interconnector 190 is shared by two adjacent reaction units 100U, and the interconnector 190 ensures electrical continuity between the two adjacent reaction units 100U. In other words, the multiple reaction units 100U included in the fuel cell stack 10 are electrically connected in series. Furthermore, a second terminal plate 250 is electrically connected to the reaction unit 100U located at one end (the lower end in FIG. 2 ) of the multiple reaction units 100U, and a first terminal plate 240 is electrically connected to the reaction unit 100U located at the other end (the upper end in FIG. 2 ). As a result, electrical energy generated in each reaction unit 100U is extracted from the terminal plates 240, 250, which function as output terminals of the fuel cell stack 10. Since SOFCs generate electricity at relatively high temperatures (e.g., 700°C to 1000°C), after startup, the fuel cell stack 10 may be heated by a heater (not shown) until the high temperature can be maintained using the heat generated by power generation.

[0074] 2 and 4, the oxidant off-gas OOG discharged from the air chamber 313 of each reaction unit 100U to the oxidant gas discharge manifold 312 is discharged to the outside of the fuel cell stack 10 through the inside of the main body 281. Also, as shown in FIGS. 3 and 5, the fuel off-gas FOG discharged from the fuel chamber 323 of each reaction unit 100U to the fuel gas discharge manifold 322 is discharged to the outside of the fuel cell stack 10 through the inside of the main body 281.

[0075] The base plate 600 and IC separator 180E are electrically connected to the unit cell 110. In contrast, the second end plate 270 is insulated from the other members constituting the fuel cell stack 10 by the insulating second plate 260, and is not electrically connected to the unit cell 110. Therefore, a potential difference occurs between the base plate 600 and the second end plate 270 when the fuel cell stack 10 is in operation.

[0076] For example, when a glass seal member is used to seal the gap between second end plate 270 and base plate 600, the seal member may peel off from second end plate 270 due to a potential difference between second end plate 270 and base plate 600. The mechanism of peeling is believed to be as follows. The following describes a case in which stainless steel is used as the material for second end plate 270, but it is believed that a similar phenomenon would occur even if another material is used. Furthermore, the following describes a case in which first terminal plate 240 is the positive output terminal and second terminal plate 250 is the negative output terminal, but it is believed that a similar phenomenon would occur even if first terminal plate 240 is the negative output terminal and second terminal plate 250 is the positive output terminal.

[0077] When a potential difference occurs between the second end plate 270 and the base plate 600, a leakage current flows through the sealing member. At this time, iron elements contained in the second end plate 270 are ionized, causing pitting corrosion on the surface of the second end plate 270. Meanwhile, components contained in the glass are ionized, and negative oxygen ions migrate toward the positive second end plate 270. These oxygen ions react with iron ions to form iron oxide between the base material of the second end plate 270 and the oxide film. Alternatively, some iron elements are dissolved in the oxide film. As a result, the bonding strength at the interface between the second end plate 270 and the sealing member decreases. Meanwhile, an oxide film is again formed on the surface of the second end plate 270 where pitting corrosion occurred. This causes peeling between the base material of the second end plate 270 and the oxide film, causing the sealing member to peel off from the second end plate 270.

[0078] To reduce the occurrence of peeling, a sealing member with a three-layer structure including two glass layers and an insulating layer disposed between the two glass layers has been proposed, as described above. With such a sealing member, the insulating layer prevents ions from moving in the glass, which is thought to reduce the occurrence of peeling of the sealing member.

[0079] However, because the distance between the second end plate 270 and the base plate 600 is generally narrow, applying a three-layer seal increases the ratio of the sum of the dimensional tolerances of the layers of the seal to the distance between the second end plate 270 and the base plate 600. In other words, the dimensional tolerances of the layers of the seal increase their impact. This raises concerns about poor bonding or damage to the seal. Simply increasing the distance between the second end plate 270 and the base plate 600 in an attempt to solve this problem would result in an increase in the size of the fuel cell stack 10, which would increase the amount of heat dissipated by the fuel cell stack 10 and increase manufacturing costs.

[0080] In this embodiment, the object bonded to second end plate 270 via seal member 500 is IC separator 180E, which is located farther from second end plate 270 than base plate 600. That is, as shown in Fig. 7, base plate 600 is arranged between a first imaginary plane P1 including the bonding surface between second end plate 270 and first glass seal 510, and a second imaginary plane P2 including the bonding surface between IC separator 180E and second glass seal 520. Seal holes 261, 601, 612 are formed in base plate 600, second plate 260, and third plate 610, which are arranged between second end plate 270 and IC separator 180E, and seal member 500 is arranged inside these seal holes. With this configuration, a large space can be secured between the second end plate 270 and the IC separator 180E, which are two components joined by the seal member 500, for arranging the seal member 500, without increasing the size of the fuel cell stack 10. This reduces the effects of dimensional tolerances of the first glass seal 510, second glass seal 520, and intermediate seal 530 provided in the seal member 500, reducing the occurrence of poor joining and cracks in the seal member 500.

[0081] In this embodiment, there is a gap between the base plate 600 and the intermediate seal 530. With this configuration, the base plate 600 and the intermediate seal 530 are not in contact with each other, which prevents leakage current from flowing to the first glass seal 510 or the second glass seal 520 via the intermediate seal 530. This reduces the occurrence of peeling of the seal member 500 from the second end plate 270.

[0082] Furthermore, the distance between the intermediate seal 530 and the second plate 260 is smaller than the distance between the intermediate seal 530 and the base plate 600. Similarly, the distance between the intermediate seal 530 and the third plate 610 is smaller than the distance between the intermediate seal 530 and the base plate 600. With this configuration, contact between the base plate 600 and the intermediate seal 530 is prevented by the second plate 260 and the third plate 610, thereby suppressing leakage current from flowing to the first glass seal 510 or the second glass seal 520 via the intermediate seal 530. This reduces the occurrence of peeling of the seal member 500 from the second end plate 270.

[0083] (Action and effect) As described above, the fuel cell stack 10 of this embodiment includes the second end plate 270, the IC separator 180E, and the seal member 500 that joins the second end plate 270 and the IC separator 180E. The seal member 500 includes a first glass seal 510, a second glass seal 520, and an intermediate seal 530. The first glass seal 510 is made of glass and is joined to the second end plate 270. The second glass seal 520 is also made of glass and is joined to the IC separator 180E. The intermediate seal 530 is made of insulating ceramic and is disposed between the first glass seal 510 and the second glass seal 520. A base plate 600 is disposed between a first imaginary plane P1 that includes the joining surface between the second end plate 270 and the first glass seal 510, and a second imaginary plane P2 that includes the joining surface between the IC separator 180E and the second glass seal 520. The base plate 600 is electrically connected to the IC separator 180E.

[0084] According to the above configuration, a large space for disposing the seal member 500 can be secured between the second end plate 270 and the IC separator 180E without increasing the size of the fuel cell stack 10. This reduces the occurrence of poor bonding or cracks in the seal member 500.

[0085] More specifically, the base plate 600 has a first seal hole 601 , and at least a portion of the seal member 500 is disposed inside the first seal hole 601 .

[0086] With this configuration, a space for disposing the seal member 500 between the second end plate 270 and the IC separator 180E can be easily secured without increasing the size of the fuel cell stack 10.

[0087] There is a gap between the base plate 600 and the intermediate seal 530. With this configuration, the base plate 600 and the intermediate seal 530 are not in contact with each other, which prevents leakage current from flowing to the first glass seal 510 or the second glass seal 520 via the intermediate seal 530. This reduces the occurrence of peeling of the seal member 500 from the second end plate 270.

[0088] The fuel cell stack 10 further includes a second plate 260 and a third plate 610 disposed between the base plate 600 and the second end plate 270. The second plate 260 includes a second seal hole 261, and the third plate 610 includes a third seal hole 612. A portion of the seal member 500 is disposed inside the second seal hole 261 and the third seal hole 612. The distance between the intermediate seal 530 and the second plate 260 is smaller than the distance between the intermediate seal 530 and the base plate 600.

[0089] With this configuration, contact between the base plate 600 and the intermediate seal 530 is prevented by the second plate 260 and the third plate 610, which prevents leakage current from flowing to the first glass seal 510 or the second glass seal 520 via the intermediate seal 530. This reduces the occurrence of peeling of the seal member 500 from the second end plate 270.

[0090] B. Second embodiment The second embodiment will be described with reference to Fig. 9. In this embodiment, a second end plate 270 (an example of a first member to be joined) and a base plate 600B (an example of a second member to be joined) are joined by a first seal member 500B (an example of a seal member). In this embodiment, the same components as in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0091] Similar to the first embodiment, a third plate 610, a base plate 600B, and a second plate 260 (an example of an insulating member) are stacked in this order between the IC separator 180E and the second end plate 270.

[0092] The base plate 600B has four manifold holes. The four manifold holes are holes that penetrate the base plate 600B and are respectively part of the manifolds 311, 312, 321, and 322. Of the four manifold holes provided in the base plate 600B, the manifold hole that forms part of the oxidant gas supply manifold 311 will be referred to below as the "manifold hole 311H3."

[0093] A second seal member 540 is disposed inside the third seal hole 612 of the third plate 610. The second seal member 540 is a cylindrical member with openings on both ends. The second seal member 540 is made of, for example, SiO2-B2O3-MgO-based glass. One end of the second seal member 540 is joined to the IC separator 180E, and the other end is joined to the base plate 600B. The oxidizer gas supply manifold 311 penetrates the interior of the second seal member 540. In other words, the internal space of the second seal member 540 is part of the oxidizer gas supply manifold 311.

[0094] The base plate 600B has an opposing surface 602 facing the second end plate 270, and a recess 603 disposed on the opposing surface 602 and defined by a bottom surface 604 and a side surface 605. The bottom surface 604 is disposed farther away from the second end plate 270 than the opposing surface 602 and is a surface parallel to the opposing surface 602, and the side surface 605 connects the bottom surface 604 and the opposing surface 602 and is a surface perpendicular to the opposing surface 602. The recess 603 is disposed around the manifold hole 311H3.

[0095] The recess 603 is disposed concentrically with a second seal hole 261 (an example of an insulating seal hole) provided in the second plate 260. Inside the recess 603 and the second seal hole 261, a first seal member 500B is disposed.

[0096] The first seal member 500B comprises a first glass seal 510B, a second glass seal 520B, and an intermediate seal 530B, which are arranged in that order.

[0097] The first glass seal 510B is made of glass and is an annular member having a first through-hole 511B, as in the first embodiment. One surface of the first glass seal 510 is bonded to the second end plate 270, and the other surface is bonded to the intermediate seal 530B.

[0098] The second glass seal 520B is made of glass and is an annular member having a second through-hole 521B, as in the first embodiment. One surface of the second glass seal 520B is bonded to the bottom surface 604 of the base plate 600B, and the other surface is bonded to the intermediate seal 530B.

[0099] The intermediate seal 530B is an annular member made of insulating ceramics and has a third through-hole 531B, as in the first embodiment. The intermediate seal 530B is sandwiched between the first glass seal 510B and the second glass seal 520B.

[0100] The first glass seal 510B, the second glass seal 520B, and the intermediate seal 530B are concentrically arranged so that the first through-hole 511B, the second through-hole 521B, and the third through-hole 531B are connected to each other. The three through-holes 511B, 521B, and 531B are part of the oxidizing gas supply manifold 311.

[0101] There is a gap between the base plate 600B and the intermediate seal 530B. Furthermore, the distance between the intermediate seal 530B and the second plate 260 is smaller than the distance between the intermediate seal 530B and the base plate 600B. More specifically, the distance D2B between the outer peripheral surface of the intermediate seal 530B and the inner peripheral surface of the second seal hole 261 is smaller than the distance D1B between the outer peripheral surface of the intermediate seal 530B and the side surface 605 of the recess 603.

[0102] As described above, according to this embodiment, a portion of the base plate 600B is disposed between a first imaginary plane P1 including the bonding surface between the second end plate 270 and the first glass seal 510B, and a second imaginary plane P2B including the bonding surface between the base plate 600B and the second glass seal 520B.

[0103] With this configuration, a large space can be secured between the second end plate 270 and the base plate 600B for arranging the seal member 500 without increasing the size of the fuel cell stack 10. This reduces the occurrence of poor bonding or cracks in the seal member 500.

[0104] More specifically, the base plate 600B has an opposing surface 602 facing the second end plate 270 and a recess 603 arranged in the opposing surface 602, and a portion of the first seal member 500B is arranged inside the recess 603.

[0105] With this configuration, a space for arranging the seal member 500 can be easily secured between the second end plate 270 and the base plate 600B without increasing the size of the fuel cell stack 10. Furthermore, a certain thickness is secured for the portion of the base plate 600B where the seal member 500 is joined, i.e., the portion where the recess 603 is located, and other portions, so that the strength of the base plate 600B is secured.

[0106] There is a gap between the base plate 600B and the intermediate seal 530B. With this configuration, the base plate 600B and the intermediate seal 530B are not in contact with each other, which prevents leakage current from flowing to the first glass seal 510 or the second glass seal 520 via the intermediate seal 530B. This reduces the occurrence of peeling of the first seal member 500B from the second end plate 270.

[0107] The distance between the intermediate seal 530B and the second plate 260 is smaller than the distance between the intermediate seal 530B and the base plate 600B. With this configuration, contact between the base plate 600B and the intermediate seal 530B is prevented by the second plate 260, thereby preventing leakage current from flowing to the first glass seal 510B or the second glass seal 520B via the intermediate seal 530B. This reduces the occurrence of peeling of the first seal member 500B from the second end plate 270.

[0108] C. Variations The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the spirit thereof, for example, the following modifications are also possible. (1) The first member to be joined may be a member different from the second end plate 270. The first member to be joined may be, for example, a single cell, or a member (e.g., a separator) that is different from the single cell among the members that make up the electrochemical reaction cell stack, or a stress relief member that is disposed on the surface of the second end plate and that relieves stress caused by external forces applied to the second end plate. The second member to be joined may also be a member different from the IC separator 180E and the base plate 600, as long as it is a member different from the first member to be joined among the members that make up the electrochemical reaction cell stack. (2) In the above embodiment, the seal members 500, 500B are arranged around the manifolds 311, 312, 321, 322, but the seal members may be arranged at positions other than the manifolds. (3) In the first embodiment, the base plate 600, the second plate 260, and the third plate 610 are arranged between the first imaginary plane P1 and the second imaginary plane P2, but two or more conductive members may be arranged between the first imaginary plane P1 and the second imaginary plane P2. Also, the number of insulating members arranged between the first imaginary plane P1 and the second imaginary plane P2 may be one, or three or more. (4) In the second embodiment, a portion of the base plate 600B is disposed between the first imaginary plane P1 and the second imaginary plane P2B, but both the first and second members to be joined may be disposed between the first and second imaginary planes. More specifically, the first member to be joined may have a first recess on a surface facing the second joining member, the second member to be joined may have a second recess on a surface facing the first joining member, and one end of the sealing member may be joined to the inner wall of the first recess and the other end of the sealing member may be joined to the inner wall of the second recess. (5) In the above embodiment, the fuel cell stack 10 includes a plurality of flat-type unit cells 110, but the electrochemical reaction cell stack may include other types of unit cells (e.g., cylindrical, flat cylindrical). (6) The above configuration can also be applied to cell stacks used in other types of fuel cells, such as polymer electrolyte fuel cells (PEFCs), phosphoric acid fuel cells (PAFCs), and molten carbonate fuel cells (MCFCs), or to electrolysis cell stacks that include electrolysis cell units, which are the constituent elements of solid oxide electrolysis cells (SOECs), as single cells. [Explanation of symbols]

[0109] 10: Fuel cell stack (electrochemical reaction cell stack) 100: Power generation block 100U, 100UN: Electrochemical reaction unit 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Anode 118: Reaction prevention layer 120: Single cell separator 121: Through hole 124: Joint 130: Air electrode frame 131: Through hole 140: Anode frame 141: Through hole 144: Anode current collecting member 145: Electrode opposing portion 146: Interconnector opposing portion 147: Connection portion 149: Spacer 180: IC separator 180E: IC separator (second joining target member) 181: Through hole 190: Interconnector 191: Flat plate portion 192: Air electrode current collecting portion 193: Coating layer 196: Conductive joining material 210: First end plate 211: Flat portion 212: Through hole 213: Outer convex portion 214: Inner convex portion 220: Insulating portion 230: Terminal separator 231: Through hole 232: First plate 240: First terminal plate 241: Through hole 250: Second terminal plate 251: Through hole 260: Second plate (insulating member) 261: Second seal hole (insulating seal hole) 270: Second end plate (first joining target member) 271: Flat portion 272: Through hole 273: Outer convex portion 274: Inner convex portion 275: Holding tube portion 280: Gas passage member 281: Main body portion 282: Flange portion 284: Bolt hole 311: Oxidizer gas supply manifold 311H1, 311H2, 311H3: Manifold holes 312: Oxidant gas discharge manifold 313: Air chamber 321: Fuel gas supply manifold 322: Fuel gas discharge manifold 323: Fuel chamber 500: Seal member 500B: First seal member (seal member) 510, 510B: First glass seal 511, 511B: First through hole 520, 520B: Second glass seal 521, 521B: Second through hole 530, 530B: Intermediate seal 531, 531B: Third through hole 540: Second seal member 600: Base plate (conductive member) 600B: Base plate (second joining target member) 601: First seal hole (conductive seal hole) 602: Opposing surface 603: Recess 604: Bottom surface 605: Side surface 610: Third plate 611: Through hole 612: Third seal hole (insulation seal hole) B: Bolt BH: Bolt hole FG: Fuel gasFOG: Fuel off-gas N: Nut OG: Oxidizer gas OOG: Oxidizer off-gas P1: First imaginary surface P2, P2B: Second imaginary surface

Claims

1. a first member to be joined; A second member to be joined; a seal member that joins the first member to be joined and the second member to be joined, The sealing member is a first glass seal made of glass to be joined to the first joining target member; a second glass seal made of glass that is joined to the second joining target member; an intermediate seal made of insulating ceramics and disposed between the first glass seal and the second glass seal; a conductive member electrically connected to the second joining target component or a part of the second joining target component is disposed between a first imaginary plane including a joining surface between the first joining target component and the first glass seal and a second imaginary plane including a joining surface between the second joining target component and the second glass seal; Electrochemical reaction cell stack.

2. 2. The electrochemical reaction cell stack according to claim 1, the conductive member is disposed between the first imaginary plane and the second imaginary plane, the conductive member has a conductive seal hole; At least a portion of the sealing member is disposed inside the conductive sealing hole. Electrochemical reaction cell stack.

3. 3. The electrochemical reaction cell stack according to claim 2, There is a gap between the conductive member and the intermediate seal. Electrochemical reaction cell stack.

4. The electrochemical reaction cell stack according to claim 2 or 3, further comprising an insulating member disposed between the conductive member and the first joining target member, the insulating member has an insulating seal hole, a portion of the sealing member is disposed inside the insulating seal hole, the distance between the intermediate seal and the insulating member is smaller than the distance between the intermediate seal and the conductive member; Electrochemical reaction cell stack.

5. 2. The electrochemical reaction cell stack according to claim 1, the second member to be joined has an opposing surface facing the first member to be joined and a recessed portion disposed on the opposing surface, At least a portion of the sealing member is disposed inside the recess. Electrochemical reaction cell stack.

6. 6. The electrochemical reaction cell stack according to claim 5, There is a gap between the second joining target member and the intermediate seal. Electrochemical reaction cell stack.

7. 7. The electrochemical reaction cell stack according to claim 5 or 6, further including an insulating member disposed between the first member to be joined and the second member to be joined, the insulating member has an insulating seal hole, a portion of the sealing member is disposed inside the insulating seal hole, The distance between the intermediate seal and the insulating member is smaller than the distance between the intermediate seal and the second joining target member. Electrochemical reaction cell stack.

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