Junction and electrochemical reaction cell stack

Abstract

Achieve both strength of glass joints and amount of use. [Solution] The bonded body includes a first member having a first opening, a second member having a second opening facing the first opening in a first direction, and a cylindrical glass bonding part that bonds the first member and the second member and surrounds the first opening and the second opening when viewed in the first direction. At least a portion of the glass bonding part has a third width that is narrower than both a first width of the first bonding surface and a second width of the second bonding surface in a first cross section parallel to the bonding direction of a first bonding surface between the glass bonding part and the first member and a second bonding surface between the glass bonding part and the second member.

Description

[Technical Field]

[0001] The technology disclosed herein relates to a joint and an electrochemical reaction cell stack. [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 an electrochemical reaction between hydrogen and oxygen. SOFCs are generally used in the form of a fuel cell stack in which multiple structural units (electrochemical reaction units) are arranged in a predetermined direction. A glass part is used to connect two structural units provided in the fuel cell stack (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6339495 [Patent Document 2] Patent Publication No. 2021-103635 [Patent Document 3] Japanese Patent Application Publication No. 2018-129298 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned SOFC, there has been a demand for reducing the amount of glass used while maintaining a bonded state.

[0005] 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]

[0006] The technology disclosed in this specification can be realized, for example, in the following forms. (1) A bonded structure disclosed in this specification includes a first member having a first opening, a second member having a second opening facing the first opening in a first direction, and a cylindrical glass bonding portion that bonds the first member and the second member and surrounds the first opening and the second opening when viewed in the first direction. At least a portion of the glass bonding portion has a third width that is narrower than both a first width of the first bonding surface and a second width of the second bonding surface in a first cross section parallel to the bonding direction between a first bonding surface between the glass bonding portion and the first member and a second bonding surface between the glass bonding portion and the second member. This bonded structure allows the amount of glass bonding portion to be reduced while maintaining the strength of the glass bonding portion.

[0007] (2) In the above bonded structure, the area of ​​a second cross section of at least a part of the glass bonding portion, which is parallel to the first bonding surface, may be smaller than both the area of ​​the first bonding surface and the area of ​​the second bonding surface. This configuration makes it possible to reduce the amount of glass bonding portions while ensuring the strength of the glass bonding portions.

[0008] (3) In the above bonded body, at least one of a first contact angle formed between the first bonding surface and a first side surface of the glass bonding portion and a second contact angle formed between the second bonding surface and the first side surface of the glass bonding portion may be configured to be 90° or less in the first cross section. With this configuration, the strength of the glass bonding portion is further ensured by at least one of the first contact angle and the second contact angle being 90° or less.

[0009] (4) In the bonded structure, one of the first contact angle and the second contact angle may be configured to be 1.2 times or more the other contact angle. This configuration ensures the strength of the glass bonding portion while ensuring the insulation of the glass bonding portion.

[0010] (5) In the above bonded structure, the glass of the glass bonded portion may have a crystallinity of 20% or more. This configuration ensures the strength of the glass bonded portion while ensuring the insulation of the glass bonded portion.

[0011] (6) In the above bonded structure, the porosity of the glass at the glass bonded portion may be 1% or more and 30% or less. This configuration ensures the strength of the glass bonded portion while further ensuring the insulation of the glass bonded portion.

[0012] (7) The electrochemical reaction cell stack disclosed in the present specification includes a unit cell having an electrolyte layer, an air electrode disposed on one surface of the electrolyte layer, and an anode disposed on the other surface of the electrolyte layer, and the above-mentioned assembly. The unit cell may be electrically connected to at least one of the first member and the second member of the assembly.

[0013] (8) In the electrochemical reaction cell stack, a gas chamber facing either the air electrode or the fuel electrode and a manifold communicating with the gas chamber are formed, and the assembly may have a through passage that forms part of the manifold.

[0014] 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]

[0015] [Figure 1] FIG. 1 is a perspective view showing the external configuration of a fuel cell stack according to a first embodiment; [Figure 2] FIG. 2 is a cross-sectional view showing the fuel cell stack of the first embodiment taken along line II-II in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view showing the fuel cell stack of the first 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 first embodiment, taken along the same line as line II-II in FIG. 1; [Figure 5] 3 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the first embodiment, taken along the same line as line III-III in FIG. 1; [Figure 6] An enlarged view of the area within frame F in FIG. 5. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII in FIG. 6. [Figure 8] Cross-sectional view taken along the line VIII-VIII in FIG. 6. [Figure 9] Cross-sectional view taken along the line IX-IX in Figure 6. [Figure 10] FIG. 6 is an enlarged view of the area within frame F in FIG. 5 according to the second embodiment. [Figure 11] FIG. 6 is an enlarged view of the area within frame F in FIG. 5 in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] A. First embodiment: The first embodiment will be described with reference to FIGS. 1 to 9. Each figure shows mutually orthogonal X, Y, and Z axes for specifying directions. In this specification, for convenience, the Z-axis direction will be referred to as the up-down direction, the positive Z-axis direction will be referred to as the up-down direction, and the negative Z-axis direction will be referred to as the down-down direction; however, the fuel cell stack 10 may actually be installed in a direction different from these directions. Furthermore, in this specification, the "thickness" of each member means the length of each member in the up-down direction unless otherwise specified. The fuel cell stack 10 is an example of an electrochemical reaction cell stack. The Z-axis direction is an example of a first direction.

[0017] A-1. Overall configuration of fuel cell stack 10: FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 10 of the first embodiment. FIG. 2 is a cross-sectional view of the fuel cell stack 10 of the first embodiment taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view of the fuel cell stack 10 of the first embodiment taken along line III-III in FIG. 1. The fuel cell stack 10 of this embodiment (an example of an electrochemical reaction cell stack) is used in a solid oxide fuel cell having an electrolyte layer 112 containing a solid oxide. As shown in FIGS. 1 to 3, the fuel cell stack 10 includes a power generation block 100, a terminal separator 230, a first plate 232, a second plate 260, a first terminal plate 240, a second terminal plate 250, an insulating section 220, a first end plate 210, a second end plate 270, and four gas passage members 280. The first end plate 210, insulating portion 220, terminal separator 230, first terminal plate 240, power generation block 100, second terminal plate 250, second plate 260, and second end plate 270 have rectangular outer shapes of approximately the same size and are arranged stacked in this order in a predetermined arrangement direction (the vertical direction in Figure 2).

[0018] 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.

[0019] 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).

[0020] (Overall configuration of 100U electrochemical reaction units) 4 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack 10 of the first embodiment, taken along the same line as line II-II in FIG. 1. FIG. 5 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack 10 of the first embodiment, taken along the same line as line III-III in FIG. 1. As shown in FIGS. 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, two IC separators 180, and a glass joint 135. 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 unit cell 110 is supported by a unit cell separator 120 , the two interconnectors 190 are supported by two IC separators 180 , respectively, and the anode current collecting member 144 is disposed between the unit cell 110 and the interconnectors 190 .

[0021] 4 and 5, the IC separator 180 and the interconnector 190 are shared by two adjacent reaction units 100U. However, as shown in Fig. 2, the reaction unit 100U located at one end (the lower end in Fig. 2) of the multiple reaction units 100U does not have the IC separator 180 and the interconnector 190 adjacent to the fuel electrode frame 140, and the second terminal plate 250 overlaps the fuel electrode frame 140.

[0022] (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.

[0023] 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).

[0024] (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).

[0025] (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. The cathode frame 130 has two seal holes 132 arranged on both sides of the through-hole 131.

[0026] (Glass joint 135) Each cathode frame 130 has two seal holes 132, each of which has a glass bonding portion 135 disposed therein. The glass bonding portion 135 is a cylindrical member having openings at both ends. The glass bonding portion 135 is made of crystallized glass. The glass bonding portion 135 may be made of, for example, SiO2-B2O3-MgO-based glass. One end of the glass bonding portion 135 is bonded to the single cell separator 120, and the other end is bonded to the IC separator 180. The glass bonding portion 135 will be described in detail later.

[0027] (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.

[0028] (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.

[0029] (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.

[0030] 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.

[0031] 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.

[0032] However, as described above, the reaction unit 100U located at one end (the lower end in FIG. 2) of the multiple reaction units 100U does not have an interconnector 190 on the fuel electrode 116 side. The fuel electrode 116 included in this reaction unit 100U is connected to the second terminal plate 250 via the fuel electrode current collecting member 144.

[0033] 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.

[0034] (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.

[0035] 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 serves as a fuel chamber 323 (an example of a gas chamber) 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.

[0036] 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.

[0037] (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 .

[0038] (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.

[0039] (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.

[0040] (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.

[0041] 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.

[0042] (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.

[0043] (2nd terminal plate 250) The second terminal plate 250 is a rectangular, plate-shaped member. The second terminal plate 250 is electrically conductive and 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. As described above, the second terminal plate 250 is connected to the anode 116 of the reaction unit 100U located at one end (the lower end in FIG. 2 ) of the multiple reaction units 100U via the anode current collecting member 144, thereby electrically connecting the reaction unit 100U and the second terminal plate 250. One end (the right end in FIG. 2 ) of the second terminal plate 250 protrudes laterally from the power generation block 100, and this protruding portion functions as the negative output terminal of the fuel cell stack 10.

[0044] (Second plate 260) Second plate 260 is a rectangular, flat member made of an insulating material. As shown in Figures 2 and 3, the peripheral edge of second plate 260 is sandwiched between second terminal plate 250 and second end plate 270, thereby ensuring insulation between second terminal plate 250 and second end plate 270.

[0045] (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.

[0046] (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 are 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.

[0047] 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.

[0048] 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.

[0049] As shown in FIG. 5 , the fuel gas supply manifold 321 penetrates one of the two glass joints 135 arranged inside each cathode frame 130. In other words, the through-hole 136 formed in the glass joint 135 is part of the fuel gas supply manifold 321. Similarly, the fuel gas exhaust manifold 322 penetrates the other of the two glass joints 135 arranged inside each cathode frame 130. In other words, the through-hole 136 in the glass joint 135 is part of the fuel gas exhaust manifold 322. The glass joint 135 prevents leakage of fuel gas (FG) or fuel off-gas (FOG) from the fuel gas supply manifold 321 and the fuel gas exhaust manifold 322 through the interface between the cathode frame 130 and the single cell separator 120 or the interface between the cathode frame 130 and the IC separator 180.

[0050] (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 tubular and open at both ends. 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. The other end (the upper end in FIGS. 2 and 3) of the main body portion 281 included in each of the four gas passage members 280 is joined to the second end plate 270 by, for example, welding, and the internal space of the main body portion 281 is connected to the manifolds 311, 312, 321, and 322, respectively. A gas pipe for supplying or discharging gas is connected to each of the main body portions 281.

[0051] A-2. Details of glass joint 135: FIG. 6 is an enlarged view of the area within frame F in FIG. 5. That is, FIG. 6 is a schematic diagram showing the single cell separator 120, the IC separator 180, and the glass bonding portion 135. As shown in FIG. 6, the glass bonding portion 135 is disposed between the single cell separator 120 and the IC separator 180, which are opposed in the vertical direction. An upper surface S11, which is the upper end of the glass bonding portion 135, contacts the IC separator 180. A lower surface S12, which is the lower end of the glass bonding portion 135, contacts the single cell separator 120 (the direction in which the glass bonding portion 135 contacts the IC separator 180 and the single cell separator 120 is referred to as the "bonding direction"). The IC separator 180 is an example of a first member, and the single cell separator 120 is an example of a second member. The upper surface S11 is an example of a first bonding surface, and the lower surface S12 is an example of a second bonding surface. The single cell separator 120, the IC separator 180, and the glass bonding portion 135 are an example of a bonded body.

[0052] As described above, the through hole 136 formed in the glass bonding portion 135, the hole formed in the IC separator 180 (hereinafter referred to as "opening hole 182"), and the hole formed in the single cell separator 120 (hereinafter referred to as "opening hole 122") form part of the fuel gas supply manifold 321 (see FIG. 5). In the first embodiment, the opening hole 182 and the opening hole 122 are arranged on the same axis in the up-down direction. The opening hole 182 is an example of a first opening hole. The opening hole 122 is an example of a second opening hole. The path formed by the opening hole 182, the through hole 136, and the opening hole 122 is an example of a through path. The fuel gas discharge manifold 322 is similar to the fuel gas supply manifold 321.

[0053] Glass joining portion 135 is an elliptical cylinder having through-hole 136 penetrating in the vertical direction. Specifically, when viewed in the vertical direction, both the outer and inner peripheral shapes of glass joining portion 135 are elliptical.

[0054] (Detailed shape of glass joint 135) The glass joint portion 135 has a shape that is constricted near the center in the vertical direction, as shown in Fig. 6. Details of the "constricted shape" are as follows.

[0055] As shown in FIG. 6, the glass joint portion 135 has a width W11 parallel to the upper surface S11 in any vertical cross section passing through the central axis of the fuel gas supply manifold 321 (hereinafter referred to as the "vertical cross section"). The width W11 is shorter than both the width W12 of the upper surface S11 and the width W13 of the lower surface S12. That is, the glass joint portion 135 has a constricted shape at the position of the width W11 in the vertical cross section. The width W11 is an example of a third width, the width W12 is an example of a first width, and the width W13 is an example of a second width.

[0056] Here, whether or not "the width W11 of the glass bonding portion 135 is shorter than either the width W12 or the width W13" is determined, for example, as follows: Ten top and bottom cross sections are obtained from the glass bonding portion 135. The ten top and bottom cross sections are obtained evenly in the circumferential direction of the glass bonding portion 135. The top and bottom cross sections are obtained as images using a scanning electron microscope (SEM) or the like. The widths W11, W12, and W13 are measured from each of the obtained cross section images. For each top and bottom cross section, the ratio of the width W11 to the width W12 is calculated. The median of the ratios of the width W11 to the width W12 of the ten cross sections is calculated. Similarly, the median of the ratios of the width W11 to the width W13 is calculated. If each median is less than 100%, it is determined that "the width W11 of the glass bonding portion 135 is shorter than either the width W12 or the width W13."

[0057] Specifically, in the first embodiment, the relationship between the widths W11, W12, and W13 of the glass bonding portion 135 is as follows: In ten vertical cross sections, each width W11 is 95% to 97% of the width W12 of the corresponding same cross section. The median of this ratio is approximately 96%. Furthermore, each width W11 is 87% to 95% of the corresponding width W13. The median of this ratio is approximately 91%. Therefore, the glass bonding portion 135 of the first embodiment has a width W11 that is shorter than both the widths W12 and W13. The width W11 is 70% or more and less than 100%, or may be 80% or more and less than 100%, or 90% or more and less than 100% of the width W12. The width W11 is 70% or more and less than 100%, or may be 80% or more and less than 100%, or 90% or more and less than 100% of the width W13.

[0058] Each width W12 is in the range of 89% to 98% of the corresponding width W13 of the same cross section. The median of this ratio is approximately 95%. Either width W12 or width W13 may be longer. Furthermore, width W12 may be 70% or more and 140% or less of width W13, or may be 80% or more and 125%, or may be 85% or more and 120% or less.

[0059] As shown in FIG. 6, the glass bonding portion 135 has a contact angle α1, which is the angle between the outer surface S13 and the upper surface S11 of the glass bonding portion 135, in any vertical cross section. Furthermore, the glass bonding portion 135 also has a contact angle β1, which is the angle between the outer surface S13 and the lower surface S12, in the same cross section having the contact angle α1. At least one of the contact angles α1 and β1 of the glass bonding portion 135 is 90° or less. The contact angle α1 is an example of a first contact angle. The contact angle β1 is an example of a second contact angle. The outer surface S13 is an example of a first side surface.

[0060] The contact angle α1 is, for example, the angle between the top surface S11 and the auxiliary line L12 in the vertical cross section. Specifically, the contact angle α1 is calculated using the top surface S11, the auxiliary line L11, the auxiliary line L12, and the generating line GL1. As shown in FIG. 6, the auxiliary line L11 is an auxiliary line parallel to the top surface S11. The vertical distance between the auxiliary line L11 and the top surface S11 is ¼ of the vertical length of the glass bonding portion 135. On the other hand, the auxiliary line L12 is an auxiliary line connecting points P and Q. Point P is the intersection of the top surface S11 and the generating line GL1 in the vertical cross section. Point Q is set as follows between the top surface S11 and the auxiliary line L11 in the vertical direction, based on the positional relationship between the generating line GL1 and a perpendicular line PL extending from point P to the top surface S11. If the generating line GL1 and the perpendicular line PL do not intersect, point Q is the intersection of the generating line GL1 and the auxiliary line L11. When the generating line GL1 intersects with the perpendicular line PL, the intersection point of the generating line GL1 and the perpendicular line PL is defined as point R. Point Q is the point on the generating line GL1 that is farthest from the perpendicular line PL between points P and R in the vertical direction (see Figure 10).

[0061] In the first embodiment, the generatrix GL1 does not intersect with the perpendicular line PL. The auxiliary line L12 is a line connecting a point P between the upper surface S11 and the generatrix GL1 and a point Q between the auxiliary line L11 and the generatrix GL1.

[0062] Similarly, contact angle β1 is calculated using lower surface S12, auxiliary line L13, auxiliary line L14, and generatrix GL1. Similarly to contact angles α and β, glass joining portion 135 also has contact angles γ1 and δ1 on its inner surface S14. Contact angles γ1 and δ1 are calculated in the same way as contact angle α1.

[0063] Whether or not the "contact angle α1 is 90° or less" is determined as follows. For example, ten top and bottom cross sections are obtained from the glass bonding portion 135. The ten top and bottom cross sections are obtained evenly in the circumferential direction of the glass bonding portion 135. The top and bottom cross sections can also be obtained as images using a scanning electron microscope (SEM) or the like. The contact angle α1 is calculated from the obtained cross section images using the method described above. The median of the contact angles α1 of the ten cross sections is calculated. If the median is 90° or less, it is determined that the "contact angle α1 is 90° or less." The contact angles β1, γ1, and δ1 are also determined in the same way as the contact angle α1.

[0064] In the first embodiment, the contact angle α1 of the glass bonding portion 135 is 73° to 82°. The median of the contact angle α1 is 76.5°. The contact angle β1 of the glass bonding portion 135 is 71° to 93°. The median of the contact angle β1 is 77.5°. The contact angle α1 of the glass bonding portion 135 in the first embodiment is 50° or more and 90° or less. The contact angle α1 may be 60° or more and 90° or less, or 70° or more and 90° or less. The contact angle β1 is 50° or more and 90° or less. The contact angle β1 may be 60° or more and 90° or less, or 70° or more and 90° or less. The contact angles γ1 and δ1 may be in the same range as the contact angle α1. The ratio of the contact angle α1 to the contact angle β1 is not particularly limited, but when the small contact angle is taken as 1, it may be 1.2 times or more, 1.3 times or more, or 1.5 times or more.

[0065] Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6. Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 6. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 6. That is, Fig. 7 is a schematic diagram of a cross section of glass joining portion 135 taken along width W11 and parallel to upper surface S11, as viewed from the positive direction of the Z axis. Fig. 8 is a schematic diagram of upper surface S11 of glass joining portion 135 as viewed from the positive direction of the Z axis. Fig. 9 is a schematic diagram of lower surface S12 of glass joining portion 135 as viewed from the negative direction of the Z axis.

[0066] As shown in FIG. 7, the glass bonding portion 135 has an arbitrary cross section parallel to the upper surface S11 (hereinafter referred to as a "horizontal cross section"; an example of a second cross section). As shown in FIGS. 7 to 9, the cross-sectional area Ar11 is smaller than both the area Ar12 of the upper surface S11 and the area Ar13 of the lower surface S12. Specifically, the cross-sectional area Ar11 is approximately 80% of the area Ar12. The cross-sectional area Ar11 is approximately 80% of the area Ar13. Note that the cross-sectional area Ar11 may be 60% or more and less than 100% of the area Ar12 (or area Ar13), or may be 70% or more and less than 100%, or may be 75% or more and less than 100%.

[0067] The crystallinity of the glass bonding portion 135 may be 20% or more, 35% or more, or 50% or more. The porosity of the glass bonding portion 135 may be 1% or more and 30% or less, or 5% or more and 20% or less.

[0068] The crystallinity and porosity of the glass joint 135 are determined as follows.

[0069] A cross section of the target glass joint 135 is imaged using an SEM at a magnification of 2000x and an observation area of ​​50 μm × 40 μm to obtain an SEM image. In the obtained SEM image, crystalline parts are shown in light gray, amorphous parts in dark gray, and pore parts in black.

[0070] The obtained SEM images are analyzed using image analysis software (e.g., ImageJ). In image analysis, first, a threshold is set between light gray and dark gray for the SEM images, and binarization is performed. In the binarized image, crystals are displayed in white, and amorphous and pores are displayed in black. The ratio Rw (%) of the area Aw of the white region in the observation area to the area A0 of the entire observation area in the binarized image is calculated using the following formula (1). Next, a threshold is set between dark gray and black for the SEM images, and binarization is performed. In the binarized image, crystals and amorphous regions are displayed in white, and pores are displayed in black. The ratio Ab of the area Ab of the black region in the observation area to the area A0 of the entire observation area in the binarized image is calculated using the following formula (2), and this is defined as the porosity Rp (%) of the observation area. From the calculated ratio Rw and porosity Rp, the crystallinity Rc (%) of the observation area is calculated using the following formula (3).

[0071] Rw = (Aw / A0) × 100 (1) Rp = (Ab / A0) × 100 (2) Rc={Rw / (100-Rp)}×100...(3)

[0072] The same process is performed on the other nine locations on the cross section of the target glass joint 135 to calculate the crystallinity Rc and porosity Rp. The average value of the crystallinity Rc data from the ten locations is calculated and used as the crystallinity of that glass joint 135. The average value of the porosity Rp data from the ten locations is calculated and used as the porosity of that glass joint 135.

[0073] A-3. Manufacturing method of fuel cell stack 10: An example of a method for manufacturing the fuel cell stack 10 having the above configuration will be described below.

[0074] Glass raw material powder is press-molded, and the resulting molded body is calcined at a temperature below the crystallization temperature of the glass to obtain a cylindrical glass calcined body. An air electrode frame 130 is placed on the single cell separator 120, and a glass calcined body is placed inside each of the two seal holes 132. An IC separator 180 is placed on the air electrode frame 130, and the other components that make up the fuel cell stack 10 are then layered in order to assemble the fuel cell stack 10.

[0075] Here, the vertical height of the cylindrical glass calcined body is shorter than the vertical distance between the single cell separator 120 and the IC separator 180 (i.e., the vertical width of the seal hole 132). For example, the vertical height of the cylindrical glass calcined body is approximately 90% of the vertical distance between the single cell separator 120 and the IC separator 180. This ratio may be 85% or more and less than 100%, 90% or more and less than 100%, or 95% or more and less than 100%. The single cell separator 120 and the IC separator 180 have oxide films on the surfaces that contact the glass bonding portion 135. For example, the oxide films on the single cell separator 120 and the IC separator 180 are formed by prior heat treatment at approximately 900°C. This temperature may be 950°C or more, or 1000°C or more.

[0076] The assembled fuel cell stack 10 is placed in a firing furnace and heated to the softening temperature of the glass to melt the glass calcined body, after which it is heat-treated at a heat treatment temperature higher than the operating temperature. The softening temperature may be equal to or higher than the temperature at which the glass starts to soften, for example, 700°C. The heat treatment temperature may be equal to or higher than the temperature at which the glass starts to crystallize, for example, 850°C. This heat treatment crystallizes the glass contained in the glass calcined body, forming a glass joint 135. The glass joint 135 joins adjacent single cell separators 120 and IC separators 180.

[0077] The crystallinity of the glass joint 135 can be adjusted by adjusting the particle size of the raw material powder. Glass has the characteristic of easily crystallizing from the portion exposed to air. Because the surface of the glass raw material powder is in contact with air inside the calcined body, the smaller the surface area of ​​the glass raw material powder, the more difficult the crystallization process. In addition, the crystallinity of the glass joint 135 can be adjusted by using, for example, particles containing at least one element selected from Ba, Ca, Mg, Al, La, Ti, Cr, Zr, Ce, and B, or an oxide of at least one of these elements, as seed crystal particles.

[0078] A-4. Operation of fuel cell stack 10: 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. Also, 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.

[0079] 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.

[0080] 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.

[0081] A-5. Advantages of the First Embodiment: As described above, the glass bonding portion 135 of the first embodiment has a width W11 parallel to the upper surface S11 in the top-bottom cross section. The width W11 is shorter than both the width W12 of the upper surface S11 and the width W13 of the lower surface S12. The glass bonding portion 135 having such a structure can reduce the amount of glass bonding portion 135 used while maintaining the bond between the single cell separator 120 and the IC separator 180.

[0082] The fuel cell stack 10 heats up during operation and returns to room temperature when operation is stopped. Therefore, stress is generated in the glass joint 135 due to the difference in thermal expansion coefficient between the glass joint 135 and the unit cell separator 120 and the IC separator 180 to be joined. This stress can cause cracks in the glass joint 135. Cracks are particularly likely to occur at the corners between the top surface S11 and the outer surface S13 or the inner surface S14, and at the corners between the bottom surface S12 and the outer surface S13 or the inner surface S14 (hereinafter collectively referred to as "corners"). The glass joint 135 forms the fuel gas supply manifold 321 and the fuel gas exhaust manifold 322. Therefore, the glass joint 135, including the joint between the unit cell separator 120 and the IC separator 180, is required to have a high sealing property. Therefore, the glass joint 135 must be crack-proof. On the other hand, there was room for reducing the material of the glass joint 135.

[0083] The glass joint 135 of the first embodiment has a constriction near the center in the vertical direction. This allows the glass joint 135 to reduce material while ensuring durability against stress. As a result, the weight of the fuel cell stack 10 can be reduced.

[0084] Specifically, "reducing the material of the glass bonding portion 135" means the following. The glass bonding portion 135 is smaller than the shape of an elliptical cylinder surrounded by an upper surface S11, a lower surface S12, a virtual outer surface, and a virtual inner surface (hereinafter referred to as the "reference shape"; see FIG. 6). That is, the volume of the glass bonding portion 135 is smaller than the volume of the reference shape. The virtual outer surface is a virtual surface formed by the shortest distance between the outer periphery of the upper surface S11 and the outer periphery of the lower surface S12 (virtual line L15 in FIG. 6). The virtual inner surface is a virtual surface formed by the shortest distance between the inner periphery of the upper surface S11 and the inner periphery of the lower surface S12 (virtual line L16 in FIG. 6). For example, a cross section having a cross-sectional area Ar11 of the first embodiment (see FIG. 7) is surrounded by the virtual outer surface and the virtual inner surface of the reference shape in the same horizontal cross section. Also, for example, in the top-bottom cross section, the width W11 is located between the imaginary line L15 and the imaginary line L16 of the reference shape (see FIG. 6).

[0085] Furthermore, if the angle formed by the glass bonding portion 135 and the IC separator 180 (i.e., the external angle of the contact angles α1 and γ1) is an acute angle, stress concentrates at the corner of the glass bonding portion 135. As a result, the glass bonding portion 135 becomes more susceptible to cracking. Therefore, in the first embodiment, to prevent cracking in the glass bonding portion 135, the angle formed by the glass bonding portion 135 and the IC separator 180 is an obtuse angle. That is, the contact angles α1 and γ1 of the glass bonding portion 135 are 90° or less. This distributes stress between the glass bonding portion 135 and the IC separator 180, making the glass bonding portion 135 less likely to crack. Note that the reason for setting the contact angles β1 and δ1 to 90° or less is the same for the glass bonding portion 135 and the single cell separator 120. As a result, the fuel gas supply manifold 321 and the fuel gas discharge manifold 322, including the glass joint 135, can ensure airtightness.

[0086] The glass joint 135 of the first embodiment can be manufactured by, for example, adjusting at least one of the wettability (affinity) between the cylindrical glass calcined body and the single cell separator 120 or IC separator 180 and the vertical height of the cylindrical glass calcined body. Specifically, an oxide film is formed by oxidizing the surfaces of the single cell separator 120 and the IC separator 180 that contact the cylindrical glass calcined body. The wettability (affinity) between the cylindrical glass calcined body and the single cell separator 120 or IC separator 180 on which the oxide film is formed is improved. This makes it easier for the cylindrical glass calcined body to spread over these surfaces. Furthermore, the cylindrical glass calcined body is shorter than the vertical distance between the single cell separator 120 and the IC separator 180. In this way, the ratio of the width W11 to the width W12 (or width W13) of the glass joint 135 is reduced. That is, there is a constriction in the center of glass joining portion 135. Also, the contact angles (contact angle α1, contact angle β1, etc.) of glass joining portion 135 become smaller.

[0087] (1) The joined body of this embodiment includes an IC separator 180 having an opening 182, a single cell separator 120 having an opening 122 facing the opening 182 in the vertical direction, and a cylindrical glass joining portion 135 that joins the IC separator 180 and the single cell separator 120 and surrounds the opening 182 and the opening 122 in a vertical view. At least a portion of the glass joining portion 135 has a width W11 that is narrower than both the width W12 of the upper surface S11 and the width W13 of the lower surface S12 in a vertical cross section (cross section in the Z-axis direction) in the joining direction between the upper surface S11 between the glass joining portion 135 and the IC separator 180 and the lower surface S12 between the glass joining portion 135 and the single cell separator 120. The joined body can reduce the amount of the glass joining portion 135 while ensuring the strength of the glass joining portion 135.

[0088] (2) In the bonded body of the present embodiment, the cross-sectional area Ar11 of at least a part of the glass bonding portion 135, which is a horizontal cross section parallel to the upper surface S11, may be smaller than both the area Ar12 of the upper surface S11 and the area Ar13 of the lower surface S12. This configuration allows the amount of the glass bonding portion 135 to be reduced while ensuring the strength of the glass bonding portion 135.

[0089] (3) In the bonded body of the present embodiment, in a cross section of the XZ plane, at least one of the contact angle α1 formed between the upper surface S11 and the generating line GL1 of the glass bonding portion 135 and the contact angle β1 formed between the lower surface S12 and the generating line GL1 of the glass bonding portion 135 may be configured to be 90° or less. With this configuration, the strength of the glass bonding portion 135 is further ensured by making at least one of the contact angle α1 and the contact angle β1 90° or less.

[0090] (4) In the bonded body of this embodiment, one of the contact angles α1 and β1 may be configured to be 1.2 times or more larger than the other contact angle. This configuration ensures the strength of glass bonding portion 135 while ensuring the insulation of glass bonding portion 135.

[0091] (5) In the bonded body of the present embodiment, the crystallinity of the glass of the glass bonding portion 135 may be 20% or more. This configuration ensures the strength of the glass bonding portion 135 while ensuring the insulation of the glass bonding portion 135.

[0092] (6) In the bonded body of the present embodiment, the porosity of the glass of the glass bonding portion 135 may be set to be 1% or more and 30% or less. This configuration ensures the strength of the glass bonding portion 135 while also ensuring the insulation of the glass bonding portion 135.

[0093] (7) The fuel cell stack 10 of this embodiment includes a unit cell 110 having an electrolyte layer 112, an air electrode 114 disposed on one surface of the electrolyte layer 112, and a fuel electrode 116 disposed on the other surface of the electrolyte layer 112, and the above-described assembly. The unit cell 110 may be electrically connected to at least one of the unit cell separator 120 and the IC separator 180 of the assembly.

[0094] (8) In the fuel cell stack 10 of this embodiment, a fuel chamber 323 facing the fuel electrode 116 and fuel gas manifolds 321, 322 communicating with the fuel chamber 323 are formed, and the assembly may be configured to have a through passage that forms part of the fuel gas manifolds 321, 322.

[0095] B. Second embodiment: Fig. 10 is an enlarged view of the area within frame F in Fig. 5 in the second embodiment. That is, Fig. 10 is a schematic diagram showing a single cell separator 120, an IC separator 180, and a glass bonding portion 135 different from that of the first embodiment. The second embodiment is the same as the first embodiment except for the detailed shape of the glass bonding portion 135 of the first embodiment, so the same parts will not be described.

[0096] As shown in FIG. 10, the glass bonding portion 135 of the second embodiment has, in any vertical cross section, a width W21 parallel to the upper surface S21 that is shorter than both the width W22 of the upper surface S21 and the width W23 of the lower surface S22, as in the first embodiment.

[0097] The glass bonding portion 135 of the second embodiment has a horizontal cross section having an area smaller than both the area of ​​the upper surface S21 and the area of ​​the lower surface S22, similar to the first embodiment.

[0098] 10, glass bonding portion 135 has a contact angle α2, which is the angle between outer surface S23 and upper surface S21, in any vertical cross section. Also, glass bonding portion 135 has a contact angle β2, which is the angle between outer surface S23 and lower surface S22, in the same cross section where contact angle α2 is calculated.

[0099] The median value of the contact angle α2 in the second embodiment is specifically 73°. Meanwhile, the median value of the contact angle β2 is specifically 93°. That is, in the second embodiment, one contact angle α2 is less than or equal to 90°, and the other contact angle β2 is greater than 90°. The contact angle β2 of the glass bonding portion 135 is 1.27 times the contact angle α2. That is, the ratio of the contact angle α2 to the contact angle β2 is 1.2 times or more, where the smaller contact angle is 1. The ratio of the contact angle α2 to the contact angle β2 may be 1.3 times or more, or may be 1.5 times or more. Furthermore, as shown in FIG. 10 , the glass bonding portion 135 has a contact angle γ2, which is the angle between the inner surface S24 and the upper surface S21. Furthermore, the glass bonding portion 135 has a contact angle δ2, which is the angle between the inner surface S24 and the lower surface S22. For example, the contact angle γ2 of the glass joint 135 of the second embodiment is less than or equal to 90°, and the contact angle δ2 is greater than 90°.

[0100] C. Comparison form: Fig. 11 is an enlarged view of the comparative embodiment within the frame F in Fig. 5. The comparative embodiment is the same as the first embodiment except for the detailed shape of the glass bonding portion 135 of the first embodiment, and therefore the same parts will be omitted.

[0101] As shown in FIG. 11, the glass bonding portion 135 of the comparative example has a width W31 parallel to the upper surface S31 in any vertical cross section. The width W31 is longer than both the width W32 of the upper surface S31 and the width W33 of the lower surface S32. Specifically, each width W31 is 102% to 117% of the corresponding width W32 of the same cross section. The median of this ratio is approximately 110.3%. Furthermore, each width W31 is 106% to 129% of the corresponding width W33 of the same cross section. The median of this ratio is approximately 118%.

[0102] In glass bonding portion 135 of the comparative embodiment, the cross-sectional area of ​​the horizontal cross section of glass bonding portion 135 is larger than both the cross-sectional area of ​​the upper surface S31 and the cross-sectional area of ​​the lower surface S32. That is, in the horizontal cross section of glass bonding portion 135 of the comparative embodiment, the surface having the smallest area is the upper surface S31 or the lower surface S32. Glass bonding portion 135 of the comparative embodiment has a shape that bulges horizontally near the center between the upper surface S31 and the lower surface S32.

[0103] As shown in FIG. 11, the glass bonding portion 135 of the comparative example has a contact angle α3, which is the angle between the outer surface S33 and the upper surface S31, in any vertical cross section. Furthermore, the glass bonding portion 135 also has a contact angle β3, which is the angle between the outer surface S33 and the lower surface S32, in the same cross section having the contact angle α3. Both the contact angle α3 and the contact angle β3 are greater than 90°. Specifically, the contact angle α3 of the glass bonding portion 135 of the comparative example is 100°. The contact angle β3 of the glass bonding portion 135 is 110°.

[0104] 11, glass bonding portion 135 has a contact angle γ3, which is the angle between inner surface S34 and upper surface S31. Glass bonding portion 135 also has a contact angle δ3, which is the angle between inner surface S34 and lower surface S32. Contact angles γ3 and δ3 of glass bonding portion 135 of the comparative example are both greater than 90°.

[0105] D. Variations The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0106] The first member may be a member different from the IC separator 180. The second member may be a member different from the unit cell separator 120, as long as it is a member different from the first member among the members constituting the electrochemical reaction cell stack. The upper surface S11 and the lower surface S12 of the glass bonding portion 135 do not necessarily have to be the bonding surfaces between the IC separator 180 and the unit cell separator 120.

[0107] In the above embodiment, the fuel cell stack 10 includes a plurality of flat plate type unit cells 110, but the electrochemical reaction cell stack may include other types of unit cells (for example, cylindrical, flat cylindrical).

[0108] In the above embodiment, the glass bonding portion 135 has an elliptical cylindrical shape, but the shape is not particularly limited as long as it is a cylindrical shape that surrounds the opening 122 of the single cell separator 120 and the opening 182 of the IC separator 180. For example, it may be a circular cylinder or a rectangular cylinder.

[0109] In the above embodiment, the glass joint 135 is disposed in the seal hole 132 of each cathode frame 130, but it may also be disposed in a seal hole formed in each anode frame 140. When the glass joint 135 is disposed in the seal hole of each anode frame 140, the through hole 136 of the glass joint 135 is part of the oxidant gas manifolds 311, 312.

[0110] In the above embodiment, the upper surface S11 and the lower surface S12 of the glass bonding portion 135 are parallel to each other, but they do not have to be parallel. For example, the lower surface S12 may be inclined at about 10° with respect to the upper surface S11.

[0111] In the above embodiment, the upper surface S11 and the lower surface S12 are each flat, but they do not have to be flat. For example, the upper surface S11 and the lower surface S12 may have irregularities. In this case, for example, in a vertical cross section, the width W12 of the upper surface S11 can be calculated using a line connecting the intersections of the outer surface S13 and the inner surface S14 as a reference for the upper surface S11, and an auxiliary line L11 can be drawn. Furthermore, the area Ar12 of the upper surface S11 may be the area of ​​a plane (XY plane in FIG. 6) perpendicular to the Z axis that includes the innermost point of the upper surface S11 in the vertical direction (Z axis direction) (in FIG. 6, the point furthest in the negative Z axis direction). The area Ar13 of the lower surface S12 may also be the area of ​​a similar plane.

[0112] In the above embodiment, the joining direction of the glass joining portion 135 (the direction between the upper surface S11 and the lower surface S12) is the same as the opposing direction of the opening 122 of the single cell separator 120 and the opening 182 of the IC separator 180, but it does not have to be the same. The joining direction of the glass joining portion 135 may be a direction different from the opposing direction of the opening 122 of the single cell separator 120 and the opening 182 of the IC separator 180.

[0113] In the above embodiment, the glass joint portion 135 is constricted at both the outer surface S13 and the inner surface S14 at the position of width W11 in the vertical cross section. However, as long as width W11 is narrower than both widths W12 and W13, the glass joint portion 135 does not have to be constricted at both the outer surface S13 and the inner surface S14. For example, the glass joint portion 135 may be constricted on the outer surface S13 side and bulged on the inner surface S14 side. Alternatively, the opposite may be true. Furthermore, in the first embodiment, the glass joint portion 135 is constricted at both the outer surface S13 and the inner surface S14 at the position of width W11 in the vertical cross section. However, the positions of the constrictions of the outer surface S13 and the inner surface S14 may be offset in the vertical direction.

[0114] In the above embodiment, the width W11 and contact angles α1, β1, γ1, and δ1 of the glass bonding portion 135 are calculated at 10 vertical cross sections of the glass bonding portion 135, but the number of cross sections does not have to be 10. For example, 20 vertical cross sections may be used. Alternatively, 5 vertical cross sections may be used.

[0115] In the above embodiment, the median of the ratio of width W11 to width W12 (or width W13) is used to determine whether "glass joint portion 135 has width W11 shorter than both width W12 and width W13." However, the median is not necessary. For example, the value of a sample portion corresponding to 70% from the lower limit of the calculation results of the ratio of width W11 to width W12 (or width W13) may be used as the criterion value (e.g., if there are 10 upper and lower cross sections, the calculation results are sorted in ascending order, and the calculation result of the seventh sample from the lower limit) may be used as the criterion value. Alternatively, the maximum value of the calculation results of the ratio of width W11 to width W12 (or width W13) may be used as the criterion value. Note that if the maximum value is used as the criterion, glass joint portion 135 is constricted over the entire circumference. On the other hand, if the median or the value of a sample portion corresponding to 70% from the lower limit is used as the criterion value, glass joint portion 135 is partially constricted.

[0116] In the above embodiment, whether or not the contact angles α1, β1, γ1, and δ1 are 90° or less is determined based on their medians, but this does not have to be the median. For example, 70% or more of the measurement results may be 90° or less. Also, all of the measurement results may be 90° or less.

[0117] In the above embodiment, the vertical height of the cylindrical glass calcined body is approximately 90% of the vertical distance between the single cell separator 120 and the IC separator 180, but is not limited to this. For example, it may be approximately 75% or more and less than 100%, or 80% or more and less than 100%. Furthermore, the oxide coatings of the single cell separator 120 and the IC separator 180 are formed by heat treatment at approximately 900°C, but is not limited to this temperature. For example, it may be 800°C or more and 1100°C or less, or 850°C or more and 1050°C or less.

[0118] The standard deviation of the crystallinity of the glass joint 135 of the above embodiment is not particularly limited, but may be, for example, 10% or less, 8.8%, or 6.7%. The shape of the glass crystals of the glass joint 135 of the above embodiment is not particularly limited, but may be rod-shaped particles. In this case, the average orientation angle of the rod-shaped crystals may be 45° or more and 90° or less with respect to the outer surface S13 or the inner surface S14. The average aspect ratio of the rod-shaped crystals may be 3 or more. The crystallinity of the outer surface S13 and the inner surface S14 of the glass joint 135 of the above embodiment may be higher than that of the inside of the glass joint 135.

[0119] 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, as single cells, electrolysis cell units, which are constituent elements of solid oxide electrolysis cells (SOECs). [Explanation of symbols]

[0120] 10: fuel cell stack 100: power generation block 100U: reaction unit 110: single cell 112: electrolyte layer 114: air electrode 116: fuel electrode 118: reaction prevention layer 120: single cell separator 122: opening hole 124: joint portion 130: air electrode frame 132: seal hole 135: glass joint portion 136: through hole 140: fuel electrode frame 144: fuel electrode current collecting member 145: electrode facing portion 146: interconnector facing portion 149: spacer 180: IC separator 182: opening hole 190: interconnector 191: flat plate portion 192: air electrode current collecting portion 193: coating layer 196: conductive bonding material 210: first end plate 220: insulating portion 230: terminal separator 232: first plate 240: First terminal plate 250: Second terminal plate 260: Second plate 270: Second end plate 280: Gas passage member 281: Main body 282: Flange 284: Bolt hole 311: Oxidizer gas supply manifold 312: Oxidizer gas discharge manifold 313: Air chamber 321: Fuel gas supply manifold 322: Fuel gas discharge manifold 323: Fuel chamber B: Bolt BH: Bolt hole FG: Fuel gas FOG: Fuel off-gas N: Nut OG: Oxidizer gas OOG: Oxidizer off-gas

Claims

1. A conjugate comprising: a first member having a first opening; a second member having a second opening facing the first opening in a first direction; a cylindrical glass joining portion that joins the first member and the second member and surrounds the first opening hole and the second opening hole when viewed in the first direction; Equipped with At least a portion of the glass joining portion has a third width narrower than both a first width of the first joining surface and a second width of the second joining surface in a first cross section parallel to a joining direction of a first joining surface between the glass joining portion and the first member and a second joining surface between the glass joining portion and the second member. zygote.

2. The bonded body according to claim 1, an area of ​​a second cross section of at least a part of the glass bonding portion, the second cross section being parallel to the first bonding surface, is smaller than both an area of ​​the first bonding surface and an area of ​​the second bonding surface; zygote.

3. The bonded body according to claim 2, In the first cross section, at least one of a first contact angle formed between the first bonding surface and a first side surface of the glass bonding portion and a second contact angle formed between the second bonding surface and the first side surface of the glass bonding portion is 90° or less. zygote.

4. The bonded body according to claim 3, One of the first contact angle and the second contact angle is 1.2 times or more larger than the other contact angle. zygote.

5. The bonded body according to claim 1, The crystallinity of the glass at the glass joint is 20% or more. zygote.

6. The bonded body according to claim 1, the porosity of the glass at the glass joint is 1% or more and 30% or less; zygote.

7. a single cell having an electrolyte layer, an air electrode disposed on one surface of the electrolyte layer, and a fuel electrode disposed on the other surface of the electrolyte layer; The bonded body according to any one of claims 1 to 6, The unit cell is electrically connected to at least one of the first member and the second member of the assembly. Electrochemical reaction cell stack.

8. The electrochemical reaction cell stack according to claim 7, The electrochemical reaction cell stack is formed with a gas chamber facing either the air electrode or the fuel electrode, and a manifold communicating with the gas chamber, The joining body has a through passage that forms a part of the manifold. Electrochemical reaction cell stack.

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