Glass member and electrochemical reaction cell stack

Abstract

To suppress the occurrence of a crack in a glass member used in an electrochemical reaction cell stack.SOLUTION: A glass member for use in an electrochemical reaction cell stack has a resistance value at 700°C that is 5 times or less than a resistance value at 750°C.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Solid oxide fuel cells (hereinafter referred to as "SOFCs") are known as one type of fuel cell that generates electricity by utilizing an electrochemical reaction between hydrogen and oxygen. SOFCs are generally used in the form of a fuel cell stack. The fuel cell stack includes glass members. A glass seal member used in a cell stack for joining a manifold made of an alloy material containing Cr to a fuel cell has been disclosed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-107593 A Summary of the Invention [Problem to be solved by the invention]

[0004] The glass member used in the fuel cell stack may have a non-uniform temperature distribution during the operation of the fuel cell stack. The resistivity of the glass member is temperature dependent, and the higher the temperature, the lower the resistivity, so that a difference in resistance occurs between a relatively high temperature portion and a relatively low temperature portion of the glass member. In this case, when the glass member is disposed between, for example, a single cell or a conductive member electrically connected to the single cell and a metal member, a large current flows locally in the relatively high temperature portion of the glass member, and a large current also flows in a portion of the metal member that contacts the relatively high temperature portion of the glass member. In the portion of the metal member through which a large current flows, a change in volume may occur, for example, due to a change in the valence of the metal and the generation of another metal compound, and as a result, for example, a crack may occur in the glass member located near the boundary between a portion of the metal member where a volume change has occurred and a portion where no volume change has occurred.

[0005] Such an issue is also common to glass members used in electrolysis cell stacks, which are a type of electrolysis cell (hereinafter referred to as "SOEC") that generates hydrogen by utilizing the electrolysis reaction of water. In this specification, a single fuel cell and a single electrolysis cell are collectively referred to as a single electrochemical reaction cell, and a fuel cell stack and an electrolysis cell stack are collectively referred to as an electrochemical reaction cell stack. Furthermore, such an issue is not limited to SOFCs and SOECs, but is also common to other types of electrochemical reaction cell stacks.

[0006] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The technology disclosed in this specification can be realized, for example, in the following forms.

[0008] (1) The glass member disclosed in this specification is a glass member used in an electrochemical reaction cell stack, and has a resistance value at 700° C. or less that is five times the resistance value at 750° C. According to this glass member, since the resistance value at 700° C. or less is five times the resistance value at 750° C., even if the temperature distribution of the glass member becomes non-uniform, the difference in resistance value between a relatively high temperature portion and a relatively low temperature portion of the glass member is suppressed. Therefore, the occurrence of cracks in the glass member can be suppressed.

[0009] (2) The glass member may be configured such that its resistance at 700° C. is three times or less than its resistance at 750° C. With this configuration, the resistance at 700° C. is three times or less than its resistance at 750° C., so that even if the temperature distribution of the glass member becomes non-uniform, the difference in resistance between relatively high temperature portions and relatively low temperature portions of the glass member is suppressed. As a result, the occurrence of cracks in the glass member can be more effectively suppressed.

[0010] (3) The electrochemical reaction cell stack disclosed in this specification may be configured to include a single cell, a metal member, the single cell or a conductive member electrically connected to the single cell, and the glass member described in (1) or (2) above, which is disposed between the single cell or the conductive member. According to this electrochemical reaction cell stack, since the glass member has a resistance value at 700°C of 5 times or less or 3 times or less than the resistance value at 750°C, even if the temperature distribution of the glass member becomes uneven, the difference in resistivity between a relatively high temperature part and a relatively low temperature part in the glass member is suppressed. Therefore, it is possible to suppress the occurrence of cracks in the glass member.

[0011] The technology disclosed in this specification can be realized in various forms, for example, in the form of glass members used in electrochemical reaction cell stacks, electrochemical reaction cell stacks, and manufacturing methods thereof. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 10 according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 10 taken along the line II-II in FIG. [Diagram 3] FIG. 2 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 10 taken along the line III-III in FIG. 1. [Figure 4] FIG. 4 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 10 taken along the line IV-IV in FIG. [Diagram 5] FIG. 3 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent generating units 100U at the same position as the cross-section shown in FIG. 2. [Figure 6] FIG. 4 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 100U at the same position as the cross-section shown in FIG. [Figure 7] FIG. 7 is an explanatory diagram showing an enlarged XZ cross-sectional configuration of the X1 portion of FIG. 6; [Figure 8] FIG. 1 is an explanatory diagram showing a schematic configuration of a test piece; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A. Embodiment: A-1. Configuration of fuel cell stack 10: FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 10 in this embodiment, FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 10 at the position II-II in FIG. 1, FIG. 3 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 10 at the position III-III in FIG. 1, and FIG. 4 is an explanatory diagram showing the YZ cross-sectional configuration of the fuel cell stack 10 at the position IV-IV in FIG. 1. Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for convenience, the Z axis direction is called the up-down direction, the Z axis positive direction is called the up direction, and the Z axis negative direction is called the down direction, but the fuel cell stack 10 may actually be installed in a direction different from these directions. The fuel cell stack 10 is an example of an electrochemical reaction cell stack in the claims.

[0014] (Overall configuration of fuel cell stack 10) 1 to 4, the fuel cell stack 10 includes a power generation block 100, an end 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, the insulating section 220, the end separator 230, the first terminal plate 240, the power generation block 100, the second terminal plate 250, the second plate 260, and the second end plate 270 have rectangular outer shapes of approximately the same size, and are arranged overlapping in this order in a predetermined arrangement direction (vertical direction).

[0015] As shown in Figures 1 and 4, 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 Figures 2 to 4, the first plate 232 is supported by the end separator 230, and the four gas passage members 280 are connected to the second end plate 270.

[0016] As shown in Figs. 2 to 4, the power generation block 100 is made up of a plurality of power generation units 100U (seven in this embodiment) arranged side by side in a predetermined arrangement direction (vertical direction).

[0017] (First end plate 210) The first end plate 210 is a member formed by pressing (bending) a single plate-shaped member, and is formed of a conductive material such as stainless steel. As shown in Figs. 1 to 4, the first end plate 210 includes a rectangular frame-shaped 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 opposite direction to 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 formed around the entire circumference of the outer 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 formed around the entire circumference of the inner periphery of the flat portion 211.

[0018] (insulating part 220) Insulating section 220 is a rectangular frame-shaped member having a through hole near the center, and is formed of, for example, an insulating material. Insulating section 220 is sandwiched between first end plate 210 and end separator 230 as shown in Fig. 2, so that insulation between first end plate 210 and end separator 230 is ensured.

[0019] (Terminal separator 230) As shown in FIGS. 2 to 4, end separator 230 is a rectangular frame-like member having a through hole 231 near the center, and is made of, for example, metal.

[0020] (First Plate 232) The first plate 232 is a rectangular flat member and is made of a conductive material such as stainless steel. As shown in Figures 2 to 4, the first plate 232 is joined to the periphery of the through hole 231 in the end separator 230 by, for example, welding. The end separator 230 and the first plate 232 separate the power generation block 100 from the external space of the fuel cell stack 10.

[0021] The first plate 232 is connected to an interconnector 190 (described below) provided in a power generating unit 100U arranged at one end (the upper end in Figure 2) of the multiple power generating units 100U that make up the power generating block 100, via a connecting member having the same structure as the anode current collecting member 144 (described below), thereby electrically connecting the power generating unit 100U and the first plate 232.

[0022] (First terminal plate 240) The first terminal plate 240 is a rectangular frame-shaped member having a through hole 241 near the center, and is made of a conductive material such as ferritic stainless steel that forms an alumina oxide film on its surface. The first terminal plate 240 is electrically connected to the power generating unit 100U arranged at one end (the upper end in FIG. 2) of the multiple power generating units 100U that make up the power generating block 100, via the first plate 232 and the end separator 230. One end (the right end in FIG. 2) of the first terminal plate 240 protrudes laterally from the power generating block 100, and this protruding portion functions as a positive output terminal for the fuel cell stack 10.

[0023] (2nd terminal plate 250) The second terminal plate 250 is a rectangular plate-like member, and is made of a conductive material such as ferritic stainless steel that forms an alumina oxide coating on its surface. The second terminal plate 250 is electrically connected to the power generating unit 100U arranged at the other end (the lower end in FIG. 2) of the multiple power generating units 100U that make up the power generating block 100. One end (the right end in FIG. 2) of the second terminal plate 250 protrudes laterally from the power generating block 100, and this protruding portion functions as a negative output terminal for the fuel cell stack 10.

[0024] (Second plate 260) The second plate 260 is a rectangular flat member and is made of, for example, an insulating material. The peripheral portion of the second plate 260 is sandwiched between the second terminal plate 250 and the second end plate 270, thereby ensuring insulation between the second terminal plate 250 and the second end plate 270.

[0025] (Second end plate 270) The second end plate 270 is a member formed by pressing (bending) a single plate-shaped member, and is formed of a conductive material such as stainless steel. The second end plate 270 includes a rectangular frame-shaped 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 opposite direction to the second terminal plate 250 (downward in FIG. 2). The flat portion 271 has holes that form the bolt holes BH described above. The outer convex portion 273 protrudes from the outer periphery of the flat portion 271. The outer convex portion 273 is formed around the entire circumference of the outer 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 formed around the entire circumference of the inner periphery of the flat portion 271.

[0026] (Manifolds 311, 312, 321, 322) 1, 2, and 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.

[0027] 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 an air chamber 313 (described later) of each power generating 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 power generating unit 100U to the outside of the fuel cell stack 10. For example, air is used as the oxidant gas OG. The oxidant gas supply manifold 311 and the oxidant gas discharge manifold 312 are disposed on opposite sides of each other with the air chamber 313 in between.

[0028] As shown in Fig. 3, the fuel gas supply manifold 321 is a gas flow path that supplies the fuel gas FG introduced from outside the fuel cell stack 10 to a fuel chamber 323 (described later) of each power generating unit 100U. The fuel gas discharge manifold 322 is a gas flow path that discharges the fuel off-gas FOG discharged from the fuel chamber 323 of each power generating 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. The fuel gas supply manifold 321 and the fuel gas discharge manifold 322 are arranged on opposite sides of the fuel chamber 323.

[0029] (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 formed with a gas through hole 283 that penetrates in the vertical direction. The flange portion 282 is provided so as to protrude outward from the other 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. One 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 gas through holes 283 are 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 (not shown).

[0030] (Overall configuration of 100U generating unit) 5 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 100U at the same position as the cross-section shown in FIG. 2. FIG. 6 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 100U at the same position as the cross-section shown in FIG. 3. As shown in FIG. 5 and FIG. 6, the power generating unit 100U includes a single cell 110, a single cell separator 120, an air electrode frame 130, a glass seal portion 135, 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 arranged in this order in a stacked manner. The unit cell 110 is supported by a unit cell separator 120 , the interconnector 190 is supported by an IC separator 180 , and the anode current collecting member 144 is disposed between the unit cell 110 and the interconnector 190 .

[0031] 5 and 6, the IC separator 180 and the interconnector 190 are shared by two adjacent power generating units 100U. However, as shown in FIG. 2, the power generating unit 100U located at the other end (the lower end in FIG. 2) of the multiple power generating units 100U does not have the IC separator 180 and interconnector 190 adjacent to the fuel electrode frame 140, and the second terminal plate 250 overlaps the fuel electrode frame 140.

[0032] (single cell 110) The unit cell 110 includes an electrolyte layer 112, an air electrode 114, an anode 116, and a reaction prevention layer 118. As shown in Figures 5 and 6, the air electrode 114, the reaction prevention layer 118, the electrolyte layer 112, and the anode 116 are arranged in this order. 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, air electrode 114, and reaction prevention layer 118) constituting the unit cell 110.

[0033] The electrolyte layer 112 is a rectangular flat member, and has one surface (upper surface in Figs. 5 and 6) on which the air electrode 114 is disposed, and the other surface (lower surface in Figs. 5 and 6) on which the fuel electrode 116 is disposed and parallel to the first surface. The electrolyte layer 112 is a layer containing a solid oxide (e.g., YSZ (yttria-stabilized zirconia)). The air electrode 114 is a layer having a rectangular shape smaller than that of the electrolyte layer 112, and contains, for example, a perovskite-type oxide (e.g., LSCF (lanthanum strontium cobalt iron oxide)). The fuel electrode 116 is a layer having a rectangular shape of approximately the same size as the electrolyte layer 112, and contains, 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 of approximately the same size as the air electrode 114, and contains, for example, GDC (gadolinium-doped ceria). The reaction prevention layer 118 has the function of preventing an element (e.g., Sr) diffused from the air electrode 114 from reacting with an element (e.g., Zr) contained in the electrolyte layer 112 to produce a highly resistive substance (e.g., SrZrO3).

[0034] (Separator for single cell 120) As shown in Fig. 5 and Fig. 6, the single cell separator 120 is a rectangular frame-like member having a substantially rectangular through-hole 121 near the center, and is made of, for example, metal. The plate thickness of the single cell separator 120 is relatively thin, 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 arranged: the upper surface in Figs. 5 and 6) by a joint 124. The joint 124 is made of, for example, a brazing material (Ag brazing). The single cell separator 120 is an example of a conductive member in the claims.

[0035] (Air electrode frame 130) 5 and 6, the air electrode frame 130 is a rectangular frame-like member having a substantially rectangular through-hole 131 near the center, and is made of, for example, mica. The thickness of the air electrode frame 130 is preferably 0.5 mm or more and 5 mm or less. As shown in FIG. 5, the air electrode frame 130 has an oxidant gas supply communication passage 132 that connects the oxidant gas supply manifold 311 and the air chamber 313, and an oxidant gas discharge communication passage 133 that connects the air chamber 313 and the oxidant gas discharge manifold 312.

[0036] (Glass seal part 135) The glass seal portion 135 is provided between the single cell separator 120 and the IC separator 180, which are opposed to each other in the vertical direction with the cathode frame 130 in between. The glass seal portion 135 is annular and is arranged so as to surround the fuel gas supply manifold 321 and the fuel gas exhaust manifold 322. The glass seal portion 135 suppresses leakage of the fuel gas FG or the 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. A detailed configuration of the glass seal portion 135 will be described later. The glass seal portion 135 is an example of a glass member in the claims.

[0037] (fuel electrode frame 140) 5 and 6, the fuel electrode frame 140 is a rectangular frame-like member having a substantially rectangular through-hole 141 near the center, and is made of, for example, metal. As shown in Fig. 6, the fuel electrode frame 140 has a fuel gas supply communication channel 142 that connects the fuel gas supply manifold 321 and the fuel chamber 323, and a fuel gas discharge communication channel 143 that connects the fuel chamber 323 and the fuel gas discharge manifold 322.

[0038] (IC separator 180) 5 and 6, IC separator 180 is a rectangular frame-like member having a through hole 181 near the center, and is made of, for example, a metal. IC separator 180 is an example of a metal member in the claims.

[0039] (Interconnector 190 and anode current collecting member 144) 5 and 6, 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 conductive and made of a metal (e.g., ferritic stainless steel). The coating layer 193 is conductive and 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 by, for example, welding.

[0040] 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 5 and 6, the anode current collecting member 144 includes an interconnector facing portion 146, an electrode facing portion 145 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 a U-shape overall. 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.

[0041] As described above, the interconnector 190 is shared by two adjacent power generating units 100U. More specifically, as shown in Fig. 5 and Fig. 6, the air electrode current collecting portion 192 is joined to the air electrode 114 of the unit cell 110 provided in one of the two adjacent power generating units 100U via a conductive bonding material 196 made of, for example, a spinel-type oxide, and is thus electrically connected to the air electrode 114. The flat plate portion 191 is electrically connected to the anode 116 of the unit cell 110 provided in the other of the two adjacent power generating units 100U via an anode current collecting member 144. This ensures electrical continuity between the two adjacent power generating units 100U.

[0042] However, as described above, the power generating unit 100U located at the other end (the lower end in FIG. 2) of the multiple power generating units 100U does not have an interconnector 190 on the anode 116 side. The anode 116 included in this power generating unit 100U is connected to the second terminal plate 250 via the anode current collecting member 144.

[0043] A spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the anode current collecting member 144 follows the deformation of the power generating unit 100U caused by temperature cycles and reactant gas pressure fluctuations, and the electrical connection between the anode 116 and the interconnector 190 (or second terminal plate 250) via the anode current collecting member 144 is maintained well.

[0044] (Air chamber 313 and fuel chamber 323) 5 and 6, the space partitioned by the single cell separator 120, the single cell 110, the air electrode frame 130, the IC separator 180, and the interconnector 190 faces the air electrode 114 and serves as an air chamber 313 through which the oxidant gas OG flows. The air electrode frame 130 partitions the air chamber 313 from the outside space all around, 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 outside space.

[0045] 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 through which the 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.

[0046] The single cell separator 120 separates the air chamber 313 and the fuel chamber 323, and suppresses 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 suppress gas leakage between adjacent power generating units 100U.

[0047] A-2. Operation of fuel cell stack 10: As shown in FIGS. 2 and 5, the oxidizing gas OG is supplied to the oxidizing gas supply manifold 311 via a gas piping (not shown) and a gas passage member 280, and is supplied to the air chamber 313 via the oxidizing gas supply communicating passage 132.

[0048] As shown in FIGS. 3 and 6, the fuel gas FG is supplied to a fuel gas supply manifold 321 via a gas piping (not shown) and a gas passage member 280, and is supplied to the fuel chamber 323 via a fuel gas supply communication passage 142.

[0049] When the oxidant gas OG is supplied to the air chamber 313 of each power generating unit 100U and the 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 generating reaction is an exothermic reaction. As described above, the interconnector 190 is shared by two adjacent power generating units 100U, and the interconnector 190 ensures electrical continuity between the two adjacent power generating units 100U. That is, the multiple power generating units 100U included in the fuel cell stack 10 are electrically connected in series. In addition, the second terminal plate 250 is electrically connected to the power generating unit 100U located at the other end (lower end of FIG. 2) of the multiple power generating units 100U, and the first terminal plate 240 is electrically connected to the power generating unit 100U located at one end (upper end of FIG. 2). As a result, electrical energy generated in each power generating unit 100U is taken out from the terminal plates 240, 250 that 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.

[0050] 2 and 5, the oxidant off-gas OOG discharged from the air chamber 313 of each power generating unit 100U to the oxidant gas discharge manifold 312 via the oxidant gas discharge communication passage 133 is discharged to the outside of the fuel cell stack 10 through the internal space of the main body 281. Also, as shown in Figures 3 and 6, the fuel off-gas FOG discharged from the fuel chamber 323 of each power generating unit 100U to the fuel gas discharge manifold 322 via the fuel gas discharge communication passage 143 is discharged to the outside of the fuel cell stack 10 through the internal space of the main body 281.

[0051] A-3. Detailed configuration of the glass seal part 135 and its surroundings: Fig. 7 is an explanatory diagram showing an enlarged XZ cross-sectional configuration of part X1 in Fig. 6. Fig. 7 shows a part of the single cell separator 120, a part of the air electrode frame 130, a part of the glass seal part 135, and a part of the IC separator 180 around the fuel gas supply manifold 321.

[0052] The glass seal portion 135 is disposed between the single cell separator 120 electrically connected to the single cell 110 via the joint portion 124 and the IC separator 180. In addition to the glass seal portion 135, an air electrode frame 130 made of mica is disposed between the single cell separator 120 and the IC separator 180. Due to this configuration, a large electric field is generated around the glass seal portion 135, for example, when the fuel cell stack 10 generates electricity. Note that, for example, in a configuration in which the fuel cell stack 10 does not include the single cell separator 120 (specifically, a configuration in which a part of the single cell 110 extends to the outer edge of the power generation block 100), the air electrode frame 130 and the glass seal portion 135 may be directly connected to the single cell 110 and disposed between the single cell 110 and the IC separator 180.

[0053] The glass seal portion 135 in this embodiment is configured so that the resistance value at 700° C. is 5 times or less, preferably 3 times or less, of the resistance value at 750° C. Examples of means for achieving such a configuration include changing the composition of the glass or changing the crystallinity of the glass. More specifically, this can be achieved by reducing the content of transition metals in the glass or increasing the firing temperature of the glass.

[0054] A-4. Advantages of this embodiment: As described above, the glass seal portion 135 of this embodiment is a glass seal portion 135 used in the fuel cell stack 10, and has a resistance value at 700° C. or less that is five times the resistance value at 750° C. According to the glass seal portion 135 of this embodiment, since the resistance value at 700° C. or less is five times the resistance value at 750° C., even if the temperature distribution of the glass seal portion 135 becomes uneven, the difference in resistance value between the relatively high temperature portion and the relatively low temperature portion of the glass seal portion 135 is suppressed. Therefore, the occurrence of cracks in the glass seal portion 135 can be suppressed.

[0055] Furthermore, in the glass seal portion 135 of this embodiment, the resistance value at 700° C. is three times or less than the resistance value at 750° C. According to the glass seal portion 135 of this embodiment, the resistance value at 700° C. is three times or less than the resistance value at 750° C., so that even if the temperature distribution of the glass seal portion 135 becomes non-uniform, the difference in resistance value between the relatively high temperature portion and the relatively low temperature portion of the glass seal portion 135 is suppressed. Therefore, the occurrence of cracks in the glass seal portion 135 can be more effectively suppressed.

[0056] The fuel cell stack 10 of this embodiment includes a single cell 110, an IC separator 180, the single cell 110 or the single cell separator 120 electrically connected to the single cell 110, and a glass seal portion 135 disposed between the IC separator 180. The fuel cell stack 10 of this embodiment includes the glass seal portion 135 whose resistance value at 700°C is 5 or less times or 3 or less times its resistance value at 750°C. Therefore, even if the temperature distribution of the glass seal portion 135 becomes non-uniform, the difference in resistivity between the relatively high temperature portion and the relatively low temperature portion of the glass seal portion 135 is suppressed. Therefore, the occurrence of cracks in the glass seal portion 135 can be suppressed.

[0057] A-5.Performance evaluation: Next, the performance evaluation of this embodiment will be described. A plurality of samples of the fuel cell stack 10, each having a glass seal portion 135 with a different temperature dependency of resistance value, were fabricated, and the crack resistance (resistance to cracks) was evaluated using the plurality of samples. Table 1 shows the performance evaluation results.

[0058] (Evaluation of temperature dependence of resistance value of glass seal portion 135) The temperature dependency of the resistance value of the glass seal portion 135 was measured using a test piece simulating the fuel cell stack 10. FIG. 8 is an explanatory diagram showing a schematic configuration of the test piece. The test piece is composed of two metal members ME and an annular glass member IM. The test piece was produced by placing the annular glass member IM between the two metal members ME, firing them at 850° C., and joining the two metal members ME with the glass member IM.

[0059] The test piece produced by the above method was subjected to evaluation of the temperature dependency of the resistance value. In the evaluation of the temperature dependency of the resistance value, first, the test piece was placed in an electric furnace, and a voltage of 20 V was applied while the test piece was heated so that the temperature around the glass member IM in the test piece was 700°C, and the resistance value at that time was measured. Next, a voltage of 20 V was applied while the temperature around the glass member IM was heated by an electric furnace so that the temperature around the glass member IM was 750°C, and the resistance value at that time was measured. The resistance value at 700°C and the resistance value at 750°C were used to evaluate the temperature dependency of the resistance value. The voltage was applied by connecting a cord connected to an external power source to each of the two metal members ME. At this time, the external power source and one of the metal members ME were connected via an ammeter. The resistance value at each temperature was obtained by dividing the voltage value (20 V) by the current value (the value indicated by the ammeter when a voltage of 20 V was applied).

[0060] (Crack resistance evaluation) The crack resistance was evaluated by the presence or absence of cracks in the glass seal portion 135 after operating the fuel cell stack 10 under certain conditions using a plurality of fuel cell stacks 10 as samples, each of which has a glass seal portion 135 whose resistance value has the same temperature dependency as the glass member IM in each of the test pieces. The fuel cell stacks 10 were first operated for 200 cycles, with one cycle being an operation in which the temperature was raised from 70°C to 700°C and then lowered to 70°C, and the presence or absence of cracks was then confirmed. The fuel cell stacks 10 in which no cracks were confirmed after the completion of the 200 cycles were operated for another 100 cycles (300 cycles in total) and then the presence or absence of cracks was confirmed. The evaluation criteria were as follows: a sample in which cracks were generated after 200 cycles was marked as "unacceptable" (x); a sample in which no cracks were generated after 200 cycles but cracks were generated after 300 cycles was marked as "passable" (△); and a sample in which no cracks were generated after 300 cycles was marked as "good". The presence or absence of cracks was determined by observation with a SEM (scanning electron microscope).

[0061] (Performance evaluation results) Table 1 shows the performance evaluation results. [Table 1]

[0062] Table 1 shows the evaluation of crack resistance of each sample. 700 / R 750 " indicates the value obtained by dividing the resistance value of the glass seal portion 135 at 700°C by the resistance value at 750°C. In other words, it indicates how many times the resistance value of the glass seal portion 135 at 700°C is larger than the resistance value at 750°C.

[0063] As shown in Table 1, R 700 / R 750 The crack resistance evaluation of the samples (S1, S2) with R values ​​greater than 5.0 was poor (×). 700 / R 750The crack resistance evaluation of the samples (S3, S4) with R values ​​of 5.0 or less and greater than 3.0 was fair. 700 / R 750 The crack resistance evaluation for all of the samples (S5 to S8) with a value of 3.0 or less was good, i.e., a circle. From these results, it was confirmed that the occurrence of cracks in glass seal portion 135 can be suppressed in a fuel cell stack 10 in which the resistance value of glass seal portion 135 at 700°C is five times or less, preferably three times or less, the resistance value at 750°C.

[0064] B. 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 of the invention. For example, the following modifications are also possible.

[0065] The configurations of the fuel cell stack 10 and the power generating units 100U in the above embodiment are merely examples and can be modified in various ways. For example, the number of unit cells 110 (the number of power generating units 100U) included in the fuel cell stack 10 in the above embodiment is merely an example, and the number of unit cells 110 is appropriately determined depending on the output voltage required for the fuel cell stack 10.

[0066] The materials constituting each member in the above embodiment are merely examples, and each member may be made of other materials.

[0067] The single cell separator 120 and the IC separator 180 in the above embodiment may have a coating such as an oxide film formed on the surface.

[0068] The fuel cell stack 10 in the above embodiment is a co-flow type SOFC, but the technology disclosed in this specification is also applicable to counter-flow type SOFCs and cross-flow type SOFCs.

[0069] In the above embodiment, the unit cell 110 is an anode-supported unit cell, but it may be another type of unit cell, such as an electrolyte-supported type or a metal-supported type.

[0070] In the above embodiment, the fuel cell stack 10 is configured to have a plurality of flat plate-type unit cells 110, but the present invention is similarly applicable to fuel cell stacks having a plurality of other types of unit cells (e.g., cylindrical, flat cylindrical, etc.).

[0071] In the above embodiment, the electrochemical reaction cell stack is a cell stack used in a solid oxide fuel cell (SOFC), but the above configuration is also applicable to cell stacks used in other types of fuel cells such as a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), and a molten carbonate fuel cell (MCFC), or an electrolysis cell stack having an electrolysis cell unit, which is a constituent unit of a solid oxide electrolysis cell (SOEC), as a single cell. [Explanation of symbols]

[0072] 10: Fuel cell stack 100: Power generation block 100U: Power generation unit 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Anode 118: Reaction prevention layer 120: Separator for single cell 121: Through hole 124: Joint 130: Air electrode frame 131: Through hole 132: Oxidant gas supply communication channel 133: Oxidant gas exhaust communication channel 135: Glass seal portion 140: Anode frame 141: Through hole 142: Fuel gas supply communication channel 143: Fuel gas exhaust communication channel 144: Anode current collecting member 145: Electrode facing portion 146: Interconnector facing portion 147: Connection portion 149: Spacer 180: IC separator 181: Through hole 190: Interconnector 191: Flat plate portion 192: Air electrode current collecting portion 193: Coating layer 196: Conductive bonding 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 260: Second plate 270: Second end plate 271: Flat portion 272: Through hole 273: Outer convex portion 274: Inner convex portion 280: Gas passage member 281: Main body portion 282: Flange portion 283: Gas through hole 284: Bolt hole 311: Oxidant gas supply manifold 312: Oxidant gas exhaust manifold 313: Air chamber 321: Fuel gas supply manifold 322: Fuel gas exhaust manifold 323: Fuel chamber B: Bolt BH: Bolt hole N: Nut FG: Fuel gas FOG: Fuel off-gas OG: Oxidizer gas OOG: Oxidizer off-gas

Claims

1. A glass member for use in an electrochemical reaction cell stack, comprising: The resistance value at 700°C is 5 times or less than the resistance value at 750°C. A glass member comprising:

2. 2. The glass member of claim 1 , The resistance value at 700°C is three times or less than the resistance value at 750°C. A glass member comprising:

3. An electrochemical reaction cell stack, comprising: A single cell, A metal member; The glass member according to claim 1 or 2 is disposed between the unit cell or a conductive member electrically connected to the unit cell, and the metal member. An electrochemical reaction cell stack comprising:

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