JP7522679B2 - Electrochemical reaction single cells and electrochemical reaction cell stacks - Google Patents

Description

The technology disclosed in this specification relates to electrochemical reaction single cells and electrochemical reaction cell stacks.

Solid oxide fuel cells (hereinafter referred to as "SOFCs") are known as one type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen. A single fuel cell (hereinafter simply referred to as a "single cell"), which is the building block of an SOFC, comprises an electrolyte layer containing solid oxide, and a fuel electrode and an air electrode that face each other in a specific direction (hereinafter referred to as the "first direction") across the electrolyte layer.

A metal-supported type single cell is known as one type of single cell. A metal-supported type single cell has a metal support placed on the opposite side of the electrolyte layer to one of the fuel electrode and air electrode (hereinafter referred to as the "specific electrode"), and the metal support supports other parts of the single cell (such as the electrolyte layer). In general, metal-supported type single cells are less susceptible to cracking due to thermal shock and have high starting performance compared to other types of single cells (e.g., fuel electrode supported type).

In a metal-supported single cell, a plurality of through holes are formed in the metal support, penetrating from one surface to the other surface of the metal support, to allow the passage of the reactive gas used for power generation. Conventionally, a configuration is known in which the fuel electrode is filled throughout all of the through holes contained in the metal support (see, for example, Patent Document 1).

JP 2005-93262 A

The longer the length (hereinafter simply referred to as the "length of the joint") in the first direction (the direction in which the fuel electrode and the air electrode face each other) of the joint where the specific electrode (e.g., the fuel electrode) and the surface of the metal support that defines the through hole are joined, the greater the joint strength between the specific electrode and the metal support, but the less gas can flow through the through hole, which reduces the performance of the single cell.

In a conventional metal-supported single cell, as described above, the specific electrode is filled throughout all of the through holes contained in the metal support, so that the length of the joint in the first direction is uniform and maximum in all of the through holes. Therefore, in this single cell, the joint strength between the specific electrode and the metal support is particularly excellent, but the flow of gas through the through holes is particularly poor, which has the disadvantage of particularly degrading the performance of the single cell.

These issues are also common to single electrolytic cells, which are the building blocks of solid oxide electrolysis cells (hereinafter referred to as "SOECs") that generate hydrogen using the electrolysis reaction of water. In this specification, single fuel cell cells and single electrolytic cells are collectively referred to as single electrochemical reaction cells.

This specification discloses a technology that can solve the above-mentioned problems.

The technology disclosed in this specification can be realized, for example, in the following forms:

(1) The electrochemical reaction single cell disclosed in this specification is an electrochemical reaction cell comprising: an electrolyte layer; a fuel electrode and an air electrode that face each other in a first direction with the electrolyte layer in between; and a metal support that is located on the opposite side of the electrolyte layer from a specific electrode that is one of the fuel electrode and the air electrode, and has a plurality of through holes that penetrate in the first direction at a position that overlaps with the specific electrode when viewed in the first direction, and in at least one of the plurality of through holes, the specific electrode is joined to a surface of the metal support that defines the through hole. In the chemical reaction unit cell, when the plurality of through holes are divided into a first through hole group consisting of one or more of the through holes and a second through hole group consisting of one or more of the through holes, the length in the first direction of the joint portion at which the specific electrode in the through hole included in the first through hole group is joined to the surface of the metal support that defines the through hole is shorter than the length in the first direction of the joint portion at which the specific electrode in the through hole included in the second through hole group is joined to the surface of the metal support that defines the through hole.

In this electrochemical reaction single cell, as described above, the length in the first direction of the joint at which the specific electrode in the through hole included in the first through hole group is joined to the surface that defines the through hole of the metal support is shorter than the length in the first direction of the joint at which the specific electrode in the through hole included in the second through hole group is joined to the surface that defines the through hole of the metal support. Therefore, according to this electrochemical reaction single cell, compared to a configuration in which the length of the joint in the first through hole group and the length of the joint in the second through hole group are equal, the flowability of gas through the through hole can be improved by the amount that the length of the joint in the first through hole group is shorter, thereby improving the performance of the electrochemical reaction single cell.

(2) In the above electrochemical reaction single cell, the number of through holes included in the second through hole group may be smaller than the number of through holes included in the first through hole group. With this electrochemical reaction single cell, the gas flow in the through hole group can be improved compared to a configuration in which the numbers are the same.

(3) In the above electrochemical reaction single cell, the number of the through holes included in the first through hole group may be smaller than the number of the through holes included in the second through hole group. With this electrochemical reaction single cell, the bonding strength between the specific electrode and the metal support can be improved compared to a configuration in which the numbers are the same.

(4) In the above electrochemical reaction single cell, the porosity of a first portion of the specific electrode located within the through hole included in one of the first through hole group and the second through hole group (hereinafter referred to as the "specific through hole group") may be greater than the porosity of a second portion of the specific electrode located within the through hole included in the other of the first through hole group and the second through hole group. According to this electrochemical reaction single cell, the porosity of the first portion of the specific electrode is greater than the porosity of the second portion, thereby improving the flow of gas through the through hole included in the specific through hole group compared to a configuration in which the porosities are equivalent.

(5) The electrochemical reaction cell stack disclosed in this specification includes a plurality of electrochemical reaction units each having an electrochemical reaction single cell described in any one of (1) to (4) above and a gas chamber facing the specific electrode, and arranged in the first direction, and in at least one of the electrochemical reaction units, the first through-hole group is located upstream of the gas flow in the gas chamber relative to the second through-hole group.

The degree of influence on the performance of the electrochemical reaction unit cell due to the length of the joint (the joint where the specific electrode and the surface defining the through hole of the metal support are joined) in the through hole varies depending on the position of the through hole in the metal support. That is, the length of the joint in a through hole located in a certain region (e.g., the upstream side of the gas flow) has a greater influence on the performance of the electrochemical reaction unit cell than the length of the joint in a through hole located in another region (e.g., the downstream side of the gas flow).

In view of this, in the present electrochemical reaction cell stack, as described above, the length in the first direction of the joint at which the specific electrode in the through hole included in the first through hole group and the surface defining the through hole of the metal support are joined is shorter than the length in the first direction of the joint at which the specific electrode in the through hole included in the second through hole group and the surface defining the through hole of the metal support are joined. The first through hole group is located in a region where the influence of the length of the joint on the performance of the electrochemical reaction single cell is relatively large (e.g., the upstream side of the gas flow), and the second through hole group, in which the length of the joint is relatively long, is located in a region where the influence is relatively small (e.g., the downstream side of the gas flow). This makes it possible to ensure both the joint strength between the specific electrode and the metal support and the performance of the electrochemical reaction single cell (and thus the performance of the electrochemical reaction cell stack) more efficiently than in the past.

The technology disclosed in this specification can be realized in various forms, such as an electrochemical reaction cell (a single fuel cell cell or a single electrolysis cell), an electrochemical reaction cell stack (a fuel cell stack or a single electrolysis cell stack) comprising multiple single electrochemical reaction cells, or a manufacturing method thereof.

FIG. 1 is a perspective view showing an external configuration of a fuel cell stack 100 according to an embodiment of the present invention; FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 taken along the line II-II in FIG. FIG. 2 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 taken along the line III-III in FIG. 1. FIG. 3 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 2 . FIG. 4 is an explanatory diagram showing the YZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 3 . FIG. 1 is an explanatory diagram showing a detailed configuration of a unit cell 110 according to the present embodiment. FIG. 1 is an explanatory diagram showing a detailed configuration of a unit cell 110 according to the present embodiment. FIG. 1 is an explanatory diagram showing a detailed configuration of a unit cell 110 according to the present embodiment. FIG. 13 is an explanatory diagram showing a detailed configuration of a unit cell 110A according to a modified example.

A. Embodiments:
A-1. Configuration of fuel cell stack 100:
FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 100 in this embodiment, FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II in FIG. 1, and FIG. 3 is an explanatory diagram showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. 1. Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for convenience, the positive direction of the Z axis is referred to as the upward direction, and the negative direction of the Z axis is referred to as the downward direction, but the fuel cell stack 100 may actually be installed in a direction different from these directions. The same applies to FIG. 4 and subsequent figures.

The fuel cell stack 100 comprises a plurality (seven in this embodiment) of fuel cell power generation units (hereinafter simply referred to as "power generation units") 102 and a pair of end plates 104, 106. The seven power generation units 102 are arranged in a predetermined arrangement direction (the Z-axis direction in this embodiment). The pair of end plates 104, 106 are arranged to sandwich the assembly made up of the seven power generation units 102 from above and below. The arrangement direction (the Z-axis direction) is an example of the first direction in the claims. The power generation units 102 are an example of the electrochemical reaction units in the claims.

A plurality of holes (eight in this embodiment) penetrating in the Z-axis direction are formed in the peripheral portion around the Z-axis direction of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100, and corresponding holes formed in each layer communicate with each other in the Z-axis direction to form through holes 108 extending in the Z-axis direction from one end plate 104 to the other end plate 106. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the through holes 108 may also be referred to as through holes 108.

A bolt 22 extending in the Z-axis direction is inserted into each through hole 108, and the fuel cell stack 100 is fastened by the bolt 22 and nuts 24 fitted on both sides of the bolt 22. As shown in Figures 2 and 3, an insulating sheet 26 is interposed between the nut 24 and each end plate 104, 106 (or a gas passage member 27 described later).

A space is provided between the outer peripheral surface of the shaft of each bolt 22 and the inner peripheral surface of each through hole 108. As shown in FIG. 1 and FIG. 2, the space formed by one bolt 22 (bolt 22A) and the through hole 108 through which the bolt 22A is inserted functions as an air electrode side gas supply manifold 161, which is a gas flow path through which oxidant gas OG (e.g., air) is introduced from outside the fuel cell stack 100 and the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102, and the space formed by the other bolt 22 (bolt 22B) and the through hole 108 through which the bolt 22B is inserted functions as an air electrode side gas exhaust manifold 162 that exhausts oxidant off-gas OOG, which is a gas exhausted from the air chamber 166 of each power generation unit 102, to the outside of the fuel cell stack 100. As shown in FIG. 1 and FIG. 3, the space formed by the other bolt 22 (bolt 22D) and the through hole 108 through which the bolt 22D is inserted functions as a fuel electrode side gas supply manifold 171 through which fuel gas FG (e.g., hydrogen-rich gas) is introduced from outside the fuel cell stack 100 and the fuel gas FG is supplied to the fuel chamber 176 of each power generation unit 102, and the space formed by the other bolt 22 (bolt 22E) and the through hole 108 through which the bolt 22E is inserted functions as a fuel electrode side gas exhaust manifold 172 that exhausts fuel off-gas FOG, which is gas exhausted from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100.

Four gas passage members 27 are provided in the fuel cell stack 100. Each gas passage member 27 has a hollow cylindrical main body 28 and a hollow cylindrical branch portion 29 branched off from the side of the main body 28. The hole of the branch portion 29 is connected to the hole of the main body 28. The hole of the main body 28 of each gas passage member 27 is connected to each manifold 161, 162, 171, 172 provided at the installation position of each gas passage member 27.

(Configuration of end plates 104, 106)
The pair of end plates 104, 106 are flat conductive members that are approximately perpendicular to the Z-axis direction and are made of, for example, stainless steel. One end plate 104 is disposed above the uppermost power generating unit 102 and is electrically connected to that power generating unit 102. The other end plate 106 is disposed below the lowermost power generating unit 102 and is electrically connected to that power generating unit 102. The upper end plate 104 functions as a positive output terminal for the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal for the fuel cell stack 100.

(Configuration of power generation unit 102)
FIG. 4 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 2, and FIG. 5 is an explanatory diagram showing the YZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 3.

As shown in Figures 4 and 5, the power generation unit 102 includes a fuel cell unit (hereinafter referred to as a "unit cell") 110, a separator 120, an air electrode side frame member 130, an air electrode side current collector 134, an anode side frame member 140, an anode side current collector 144, and a pair of interconnectors 150. Holes corresponding to the through holes 108 through which the bolts 22 described above are inserted are formed on the periphery of the separator 120, the air electrode side frame member 130, the anode side frame member 140, and the interconnector 150.

The interconnector 150 is a flat conductive member that is approximately perpendicular to the Z-axis direction, and is made of, for example, stainless steel. The interconnector 150 ensures electrical conduction between the power generation units 102 and prevents the reaction gases from mixing between the power generation units 102. In this embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by the two adjacent power generation units 102. That is, the upper interconnector 150 in one power generation unit 102 is made of the same material as the lower interconnector 150 in the other power generation unit 102 adjacent to the upper side of the power generation unit 102. In addition, the power generation unit 102 located at the top of the fuel cell stack 100 does not have an upper interconnector 150, and the power generation unit 102 located at the bottom does not have a lower interconnector 150 (see Figures 2 and 3).

The single cell 110 includes an electrolyte layer 112, and an air electrode 114 and a fuel electrode 116 that face each other in the Z-axis direction with the electrolyte layer 112 in between. The single cell 110 further includes a metal support 180 that is disposed on the opposite side (lower side) of the electrolyte layer 112 with respect to the fuel electrode 116 (more specifically, the base 117 of the fuel electrode 116, which will be described later).

The metal support 180 is a conductive member having a flat plate shape that is approximately perpendicular to the Z-axis direction, and is made of metal (e.g., stainless steel). The metal support 180 supports other components (such as the electrolyte layer 112) in the unit cell 110. In this manner, the unit cell 110 of this embodiment is a so-called metal-supported unit cell in which the mechanical strength of the unit cell 110 is ensured by the metal support 180. Compared to other types of unit cells (e.g., fuel electrode-supported type), metal-supported unit cells are less likely to crack due to thermal shock and have high starting performance. As described below, the metal support 180 has multiple through holes 50 formed therein to allow the fuel gas FG to pass through (see FIG. 6).

The electrolyte layer 112 is a flat plate-shaped member that is approximately perpendicular to the Z-axis direction and is a dense layer. In this embodiment, the electrolyte layer 112 is formed so as to continuously cover the upper surface of the fuel electrode 116 and the area of the upper surface of the metal support 180 that is not covered by the fuel electrode 116. The electrolyte layer 112 is formed of a solid oxide such as YSZ (yttria-stabilized zirconia). In this way, the single cell 110 of this embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte. The air electrode 114 is a flat plate-shaped member that is approximately perpendicular to the Z-axis direction and is a porous layer. The air electrode 114 is formed of, for example, a perovskite-type oxide (for example, LSCF (lanthanum strontium cobalt iron oxide)). The fuel electrode 116 is a flat plate-shaped member that is approximately perpendicular to the Z-axis direction and is a porous layer. The fuel electrode 116 is formed, for example, from a cermet made of Ni and oxide ion conductive ceramic particles (e.g., YSZ). In this embodiment, the fuel electrode 116 corresponds to a specific electrode in the claims.

The separator 120 is a frame-shaped member with a roughly rectangular hole 121 formed near the center that penetrates in the Z-axis direction, and is made of, for example, stainless steel. The portion of the separator 120 surrounding the hole 121 is joined to the periphery of the unit cell 110 (electrolyte layer 112) by a joint 124 that contains, for example, brazing material. The separator 120 divides the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116.

The air electrode side frame member 130 is a frame-shaped member with a substantially rectangular hole 131 formed near the center that penetrates in the Z-axis direction, and is formed of an insulator such as mica. The hole 131 of the air electrode side frame member 130 forms an air chamber 166 facing the air electrode 114. The air electrode side frame member 130 electrically insulates a pair of interconnectors 150 included in the power generation unit 102. The air electrode side frame member 130 is formed with an air electrode side gas supply communication flow path 132 that connects the air electrode side gas supply manifold 161 and the air chamber 166, and an air electrode side gas exhaust communication flow path 133 that connects the air chamber 166 and the air electrode side gas exhaust manifold 162.

The fuel electrode side frame member 140 is a frame-shaped member with a substantially rectangular hole 141 formed near the center that penetrates in the Z-axis direction, and is made of, for example, stainless steel. The hole 141 in the fuel electrode side frame member 140 forms a fuel chamber 176 that faces the fuel electrode 116. The fuel electrode side frame member 140 is formed with a fuel electrode side gas supply communication passage 142 that connects the fuel electrode side gas supply manifold 171 and the fuel chamber 176, and a fuel electrode side gas exhaust communication passage 143 that connects the fuel chamber 176 and the fuel electrode side gas exhaust manifold 172.

The air electrode side current collector 134 is composed of a plurality of roughly rectangular prism-shaped current collector elements 135 arranged in the air chamber 166, and is formed of, for example, stainless steel. The air electrode side current collector 134 electrically connects the air electrode 114 and the interconnector 150. However, since the power generation unit 102 located at the top of the fuel cell stack 100 does not have an upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 electrically connects the air electrode 114 and the upper end plate 104 (see Figures 2 and 3). The air electrode side current collector 134 and the interconnector 150 may be configured as an integrated member.

The fuel electrode side current collector 144 is composed of multiple roughly rectangular prism-shaped current collector elements 145 arranged in the fuel chamber 176, and is made of, for example, stainless steel. The fuel electrode side current collector 144 electrically connects the metal support 180 and the interconnector 150. However, since the power generation unit 102 located at the bottom of the fuel cell stack 100 does not have a lower interconnector 150, the fuel electrode side current collector 144 in that power generation unit 102 electrically connects the metal support 180 and the lower end plate 106 (see Figures 2 and 3). The fuel electrode side current collector 144 and the interconnector 150 may be configured as an integrated member.

A-2. Operation of the fuel cell stack 100:
2 and 4, the oxidant gas OG is supplied from a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the air electrode side gas supply manifold 161 through the branch portion 29 of the gas passage member 27 and a hole in the main body 28 to the air electrode side gas supply manifold 161, and is supplied from the air electrode side gas supply manifold 161 to the air chamber 166 through the air electrode side gas supply communication passage 132 of each power generation unit 102. Also, as shown in Fig. 3 and 5, the fuel gas FG is supplied from a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel electrode side gas supply manifold 171 through the branch portion 29 of the gas passage member 27 and a hole in the main body 28 to the fuel electrode side gas supply manifold 171, and is supplied from the fuel electrode side gas supply manifold 171 to the fuel chamber 176 through the fuel electrode side gas supply communication passage 142 of each power generation unit 102.

In each power generation unit 102, when the oxidant gas OG supplied to the air chamber 166 enters the porous air electrode 114 and the fuel gas FG supplied to the fuel chamber 176 enters the porous fuel electrode 116 through the multiple through holes 50 formed in the metal support 180, power is generated in the single cell 110 by an electrochemical reaction between the oxygen contained in the oxidant gas OG and the hydrogen contained in the fuel gas FG. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to one interconnector 150 via the air electrode side collector 134, and the fuel electrode 116 is electrically connected to the other interconnector 150 via the metal support 180 and the fuel electrode side collector 144. In addition, the multiple power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104, 106 that function as the output terminals of the fuel cell stack 100. In addition, since SOFCs generate electricity at relatively high temperatures (e.g., 700°C to 1000°C), after startup, the fuel cell stack 100 may be heated by a heater (not shown) until the heat generated by power generation can maintain the high temperature.

2 and 4, the oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 to the air electrode side gas discharge manifold 162 through the air electrode side gas discharge communication passage 133 passes through the main body 28 and branch 29 of the gas passage member 27 provided at the position of the air electrode side gas discharge manifold 162, and is discharged to the outside of the fuel cell stack 100 from the gas pipe (not shown) connected to the branch 29. Also, as shown in FIG. 3 and FIG. 5, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 to the fuel electrode side gas discharge manifold 172 through the fuel electrode side gas discharge communication passage 143 passes through the main body 28 and branch 29 of the gas passage member 27 provided at the position of the fuel electrode side gas discharge manifold 172, and is discharged to the outside of the fuel cell stack 100 from the gas pipe (not shown) connected to the branch 29.

A-3. Detailed configuration of the unit cell 110:
6 to 8 are explanatory diagrams showing a detailed configuration of the unit cell 110 in this embodiment. In FIG. 6, the YZ cross-sectional configuration of the unit cell 110 at the X1 portion (around the region where the first through-hole group G1 described later is located) in FIG. 5 is shown enlarged, and in FIG. 7, the YZ cross-sectional configuration of the unit cell 110 at the X2 portion (around the region where the second through-hole group G2 described later is located) in FIG. 5 is shown enlarged. Note that the interconnector 150 is omitted in FIG. 6 and FIG. 7. In FIG. 8, the XY plane configuration of the metal support 180 is shown typically.

As shown in Figures 6 and 7, in the single cell 110 of this embodiment, multiple through holes 50 are formed in the metal support 180. In the metal support 180, each through hole 50 penetrates from the upper surface S11 on the electrolyte layer 112 side, which contacts the fuel electrode 116 (more specifically, the base 117, which is a part of the fuel electrode 116 on the side closer to the electrolyte layer 112), to the lower surface S22 on the opposite side to the upper surface S11. Therefore, each through hole 50 can be said to be a hole that penetrates in the Z-axis direction.

In this embodiment, the metal support 180 has a configuration in which two plate-shaped members (a first metal member 181 and a second metal member 182) are stacked in the Z-axis direction. The second metal member 182 is disposed below the first metal member 181 and is joined to the first metal member 181 by, for example, welding. In this embodiment, the thickness of the first metal member 181 and the thickness of the second metal member 182 are approximately the same.

Each through hole 50 formed in the metal support 180 has a first portion 51 including an opening 53 in the upper surface S11 of the metal support 180. The first portion 51 of each through hole 50 is formed in the first metal member 181 constituting the metal support 180. Each first portion 51 penetrates from the upper surface S11 of the first metal member 181 that contacts the fuel electrode 116 to the lower surface S12 on the opposite side to the upper surface S11.

In addition, each through hole 50 formed in the metal support 180 has a second portion 52 that communicates with the first portion 51 in addition to the first portion 51. The second portion 52 is a portion that includes an opening 54 on the lower surface of the metal support 180 (the lower surface S22 of the second metal member 182 described later). Each second portion 52 penetrates from the upper surface S21 of the second metal member 182 that contacts the first metal member 181 to the lower surface S22 opposite to the upper surface S21. That is, in this embodiment, each through hole 50 is composed of a first portion 51 and a second portion 52. In this embodiment, in each through hole 50, the second portion 52 is positioned so that the contour line in the Z-axis direction overlaps with the contour line of the first portion 51.

As shown in FIG. 8, the multiple (192 in this embodiment) through holes 50 formed in the metal support 180 are configured as a first through hole group G1 consisting of multiple (128 in this embodiment) through holes 50, and a second through hole group G2 consisting of multiple (64 in this embodiment) through holes 50. For this reason, in this embodiment, it can be said that the number of through holes 50 included in the second through hole group G2 is smaller than the number of through holes 50 included in the first through hole group G1.

In this embodiment, the multiple through holes 50 constituting the first through hole group G1 are arranged on lattice points, 16 in the X-axis direction and 8 in the Y-axis direction. The distance between two adjacent through holes 50 in the X-axis direction is approximately constant, and the distance between two adjacent through holes 50 in the Y-axis direction is also approximately constant. The multiple through holes 50 constituting the second through hole group G2 are arranged on lattice points, 16 in the X-axis direction and 4 in the Y-axis direction.

In this embodiment, the first through-hole group G1 is located upstream (positive Y-axis direction) of the flow of fuel gas FG in the fuel chamber 176 relative to the second through-hole group G2. This is equivalent to satisfying at least one of the following conditions (1) to (3). Note that in this embodiment, all of the following conditions (1) to (3) are satisfied.
Condition (1):
At least one through hole 50 included in the first through hole group G1 is located upstream of the gas flow in the Y axis direction (the direction of the flow of fuel gas FG in the fuel chamber 176) of any of the through holes 50 in the second through hole group G2.
Condition (2):
All of the through holes 50 included in the first through hole group G1 are located upstream of the gas flow in the Y axis direction (the direction of the flow of fuel gas FG in the fuel chamber 176) of any of the through holes 50 in the second through hole group G2.
Condition (3):
A virtual straight line VL passes through a point overlapping with the unit cell 110 as viewed in the Z-axis direction and is perpendicular to the direction of the flow of the fuel gas FG in the gas chamber (the fuel chamber 176 in the above embodiment), and one of the two regions is defined as the upstream side of the gas flow, and the other is defined as the downstream side of the gas flow. All of the through holes 50 included in the first through-hole group G1 are located in one of the two regions, and all of the through holes 50 included in the second through-hole group G2 are located in the other of the two regions. The virtual straight line VL may be a straight line passing through the center point of the unit cell 110 as viewed in the Z-axis direction.

As shown in FIG. 6, in this embodiment, in each through hole 50 included in the first through hole group G1, the fuel electrode 116 is not filled in the through hole 50. In other words, the fuel electrode 116 does not have a portion located in the through hole 50 included in the first through hole group G1. Therefore, the fuel electrode 116 is not bonded to the surface of the metal support 180 that defines the through hole 50 included in the first through hole group G1. In contrast, as shown in FIG. 7, in each through hole 50 included in the second through hole group G2, the fuel electrode 116 is filled throughout the entire through hole 50. The fuel electrode 116 is connected to the base 117 and has a portion (hereinafter referred to as the "hole interior") 118 located throughout the entire range in the Z-axis direction in each through hole 50 included in the second through hole group G2, and the hole interior 118 is bonded to the surface of the metal support 180 that defines the through hole 50. That is, the fuel electrode 116 is bonded to the surface that defines each of the through holes 50 included in the second through hole group G2.

From this, it can be said that the Z-axis length LJ1 of the joint J1 at which the fuel electrode 116 in each through hole 50 included in the first through hole group G1 is joined to the surface that defines the through hole 50 in the metal support 180 (in this embodiment, the joint J1 does not exist, so the length LJ1 of the joint J1 is 0 (zero)) is shorter than the Z-axis length LJ2 of the joint J2 at which the fuel electrode 116 in each through hole 50 included in the second through hole group G2 is joined to the surface that defines the through hole 50 in the metal support 180.

As described above, since the fuel electrode 116 is not filled in each of the through holes 50 included in the first through hole group G1, a space SP is formed throughout the entire through hole 50 in each of the through holes 50 included in the first through hole group G1. The fuel electrode 116 is filled throughout the entire through hole 50 in each of the through holes 50 included in the second through hole group G2. Most of the reaction gas (fuel gas FG) supplied to the fuel chamber 176 advances through each of the through holes 50 (space SP) included in the first through hole group G1, and further advances through the gap in the base 117 of the fuel electrode 116 to be supplied to the reaction field. The reaction gas that does not enter the through holes 50 (space SP) included in the first through hole group G1 but proceeds to each of the through holes 50 included in the second through hole group G2 proceeds through the gaps in the interiors 118 of the fuel electrodes 116 filled in each of the through holes 50 included in the second through hole group G2, and further proceeds through the gaps in the base 117 of the fuel electrode 116, and is supplied to the reaction field.

In this embodiment, the shape of each through hole 50 in the XY cross section of the single cell 110 is circular. The diameter of each through hole 50 is approximately constant from the position of the opening 53 on the upper surface S11 of the metal support 180 to the position of the opening 54 on the lower surface S22. In addition, the diameters of the multiple through holes 50 are approximately the same.

The single cell 110 having such a configuration can be manufactured, for example, by the following manufacturing method. First, the first metal member 181 and the second metal member 182 constituting the metal support 180 are prepared, and the first portion 51 of each through hole 50 is formed in the first metal member 181 by a hole drilling process, and the second portion 52 of each through hole 50 is formed in the second metal member 182. Next, the first metal member 181 and the second metal member 182 are aligned so that each first portion 51 communicates with each second portion 52 (in this embodiment, and the contour line of the first portion 51 and the contour line of the second portion 52 overlap when viewed in the Z-axis direction), and are joined by, for example, welding to produce the metal support 180.

Next, pastes are prepared for forming the hole interior 118 and the base 117 of the fuel electrode 116. The paste for forming the hole interior 118 is then filled into each of the through holes 50 constituting the second through hole group G2 formed in the metal support 180. Thereafter, the paste for forming the base 117 is applied to the upper surface S11 of the metal support 180 to form a film. The paste for forming the hole interior 118 and the paste for forming the base 117 may have the same composition or may have different compositions.

Next, a paste for forming the electrolyte layer 112 is prepared and applied onto the coating of the paste for forming the base 117 of the fuel electrode 116 to form a film. The laminate thus produced is fired at a predetermined temperature to form the electrolyte layer 112 and the fuel electrode 116, and a laminate of the metal support 180, the electrolyte layer 112, and the fuel electrode 116 is obtained. Next, a paste for forming the air electrode 114 is prepared and applied onto the electrolyte layer 112 to form a film. The laminate thus produced is fired at a predetermined temperature to form the air electrode 114, and a single cell 110 having the above-mentioned configuration is obtained.

A-4. Advantages of this embodiment:
As described above, each unit cell 110 constituting the fuel cell stack 100 of this embodiment includes an electrolyte layer 112, an anode 116 and an air electrode 114 which face each other in the Z-axis direction with the electrolyte layer 112 sandwiched therebetween, and a metal support 180. The metal support 180 is a member located on the opposite side of the electrolyte layer 112 with respect to the anode 116. The metal support 180 has a plurality of through holes 50 penetrating in the Z-axis direction at positions overlapping with the anode 116 as viewed in the Z-axis direction. In each of the through holes 50 included in the second through hole group G2, the anode 116 is joined to a surface of the metal support 180 which defines the through hole 50. A length LJ1 in the Z-axis direction of a joint J1 at which the anode 116 in each through hole 50 included in the first through hole group G1 is joined to a surface defining the through hole 50 of the metal support 180 is shorter than a length LJ2 in the Z-axis direction of a joint J2 at which the anode 116 in each through hole 50 included in the second through hole group G2 is joined to a surface defining the through hole 50 of the metal support 180. Both the first through hole group G1 and the second through hole group G2 are groups constituted by a plurality of through holes 50.

In the single cell 110 of this embodiment, as described above, the length LJ1 in the Z-axis direction of the joint J1 at which the fuel electrode 116 in each through hole 50 included in the first through hole group G1 is joined to the surface that defines the through hole 50 of the metal support 180 is shorter than the length LJ2 in the Z-axis direction of the joint J2 at which the fuel electrode 116 in each through hole 50 included in the second through hole group G2 is joined to the surface that defines the through hole 50 of the metal support 180. Therefore, according to the single cell 110 of this embodiment, compared to a configuration in which the length LJ1 of the joint J1 in the first through hole group G1 and the length LJ2 of the joint J2 in the second through hole group G2 are equivalent, the flowability of gas through the through hole 50 can be improved by the amount that the length LJ1 of the joint J1 in the first through hole group G1 is shorter, thereby improving the power generation performance of the single cell 110.

In addition, in the single cell 110 of this embodiment, the number of through holes 50 included in the second through hole group G2 is smaller than the number of through holes 50 included in the first through hole group G1. Therefore, according to the single cell 110 of this embodiment, the gas flow through the through holes 50 can be improved compared to a configuration in which these numbers are the same.

The fuel cell stack 100 of this embodiment includes a plurality of power generating units 102 arranged in the Z-axis direction, each of which has the above-mentioned single cell 110 and a fuel chamber 176 facing the fuel electrode 116. In each power generating unit 102, the first through-hole group G1 is located upstream of the flow of fuel gas FG in the fuel chamber 176 relative to the second through-hole group G2.

Depending on the position of the through hole 50 in the metal support 180, the impact of the length (LJ1, LJ2) of the joint (J1, J2) in the through hole 50 on the power generation performance of the single cell 110 varies. That is, the length (LJ1, LJ2) of the joint (J1, J2) in the through hole 50 located in a certain region (e.g., upstream of the flow of fuel gas FG) has a greater impact on the power generation performance of the single cell 110 than the length (LJ1, LJ2) of the joint (J1, J2) in the through hole 50 located in another region (e.g., downstream of the flow of fuel gas FG).

In view of this, in the fuel cell stack 100 of this embodiment, as described above, the Z-axis length LJ1 of the joint J1 at which the fuel electrode 116 in each through hole 50 included in the first through hole group G1 is joined to the surface defining the through hole 50 in the metal support 180 is shorter than the Z-axis length LJ2 of the joint J2 at which the fuel electrode 116 in each through hole 50 included in the second through hole group G2 is joined to the surface defining the through hole 50 in the metal support 180. The first through-hole group G1 is located in an area (e.g., the upstream side of the gas flow) where the length (LJ1, LJ2) of the joint (J1, J2) has a relatively large effect on the power generation performance of the unit cell 110, and the second through-hole group G2, in which the length LJ2 of the joint J2 is relatively long, is located in an area (e.g., the downstream side of the gas flow) where the effect is relatively small. This makes it possible to more efficiently ensure both the bond strength between the fuel electrode 116 and the metal support 180 and the power generation performance of the unit cell 110 (and thus the power generation performance of the fuel cell stack 100) than in the past.

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.

The configuration of the fuel cell stack 100 and the single cell 110 in the above embodiment is merely an example, and various modifications are possible. For example, in the above embodiment, each through hole 50 formed in the metal support 180 is composed of a first portion 51 and a second portion 52, but the configuration of the through hole 50 is not necessarily limited to this, so long as it penetrates from one surface of the metal support 180 in the Z-axis direction to the other surface. For example, the through hole 50 formed in the metal support 180 may include a portion that extends in a direction perpendicular to the Z-axis direction.

In the above embodiment (or modified example, the same applies below), the shape of each through hole 50 of the metal support 180 in the XY cross section of the single cell 110 is circular, but it may be a shape other than circular (e.g., rectangular). Also, in the above embodiment, the diameter of each through hole 50 is approximately constant from the position of the opening 53 on the upper surface S11 of the metal support 180 to the position of the opening 54 on the lower surface S22, but it may be different at any position. Also, in the above embodiment, the configuration of the multiple through holes 50 is similar, but the configuration of any through hole may be different from the configuration of the other through holes. For example, the diameters of the multiple through holes 50 are approximately the same as each other, but they may be different from each other.

9 is an explanatory diagram showing a detailed configuration of a single cell 110A in a modified example. In the above embodiment, the fuel electrode 116 does not have a portion located within the through hole 50 included in the first through hole group G1, and is not joined to the surface of the metal support 180 that defines the through hole 50 included in the first through hole group G1. However, as in the example shown in FIG. 9, for example, "the length LJ1 in the Z-axis direction of the joint J1 at which the fuel electrode 116 in each through hole 50 included in the first through hole group G1 and the surface defining the through hole 50 of the metal support 180 are joined is longer than the length LJ1 of the fuel electrode 116 in each through hole 50 included in the second through hole group G2." As long as the condition (hereinafter referred to as the "specific condition") that the length LJ1 of the joint J1 in the first through-hole group G1 is shorter than the length LJ2 in the Z-axis direction of the joint J2 at which the joint J1 in the first through-hole group G1 is joined to the surface defining the through-hole 50 of the metal support 180 is satisfied, the fuel electrode 116 may have a portion (hereinafter referred to as the "hole interior") 118A that is connected to the base 117 and located within the through-hole 50 included in the first through-hole group G1 (more specifically, located in only a part of the through-hole 50 in the Z-axis direction), and the hole interior 118A may be joined to the surface defining the through-hole 50 of the metal support 180. Even in such a configuration, by satisfying the specific condition, the flowability of gas passing through the through-hole 50 can be improved by the amount that the length LJ1 of the joint J1 in the first through-hole group G1 is shorter, as in the above embodiment, and thus the power generation performance of the single cell 110A can be improved. In the above embodiment, the fuel electrode 116 is located in the through hole 50 included in the second through hole group G2, and the hole interior 118 is located in the entire range in the Z axis direction, but it may be located only in a part of the through hole 50 in the Z axis direction. The configuration in which the fuel electrode 116 is located only in a part of the through hole 50 in the metal support 180 in the Z axis direction can be realized (manufactured) by filling, for example, a part of the bottom of each through hole 50 of the metal support 180 (a part on the lower side of the second part 52) with resin in the above-mentioned manufacturing method, so that the paste for forming the hole interior 118A is not filled in the hole interior 118A.

In a configuration in which the fuel electrode 116 includes a portion 118A located in the through hole 50 included in the first through hole group G1, the porosity P1 of the portion 118A located in each through hole 50 included in the first through hole group G1 of the fuel electrode 116 may be greater than the porosity P2 of the hole interior 118 located in each through hole 50 included in the second through hole group G2 of the fuel electrode 116. With this configuration, the gas flowability in the through hole 50 included in the second through hole group G2 can be improved compared to a configuration in which these porosities (P1, P2) are equivalent. In this example, the portion 118A of the fuel electrode 116 located in each through hole 50 included in the first through hole group G1 is an example of the first portion in the claims, and the hole interior 118 of the fuel electrode 116 located in each through hole 50 included in the second through hole group G2 is an example of the second portion in the claims. In addition, a configuration may be adopted in which the porosity P2 of the hole interior 118 located in each through hole 50 included in the second through hole group G2 of the anode 116 is larger than the porosity P1 of the portion 118A located in each through hole 50 included in the first through hole group G1 of the anode 116. In this configuration, the gas flowability in the through hole 50 included in the first through hole group G1 can be improved compared to a configuration in which these porosities (P1, P2) are equivalent. In this example, the hole interior 118 located in each through hole 50 included in the second through hole group G2 of the anode 116 is an example of the first portion in the claims, and the portion 118A located in each through hole 50 included in the first through hole group G1 of the anode 116 is an example of the second portion in the claims. The porosity (P1, P2) of each portion (118, 118A) constituting the anode 116 can be measured, for example, as follows. First, a cross section of the portion of the fuel electrode 116 located within the through hole 50 is observed, for example, at a magnification of 1000 to 3000 times using a SEM (scanning electron microscope), and the total area of the above portion of the fuel electrode 116 including the pores and the total area of the pores are calculated for the observed field of view by image analysis. Then, the porosity (P1, P2) is calculated using the formula: (total area of the pores/(total area of the above portion of the fuel electrode 116 including the pores)) x 100 (%). The porosity of each portion (118, 118A) constituting the fuel electrode 116 can be adjusted, for example, by adjusting the amount of pore-forming material added when preparing the paste that forms each portion. Specifically, the more the amount of pore-forming material added when preparing the paste, the higher the porosity.

In the above embodiment, the configuration satisfies all of the above conditions (1) to (3), but the configuration may also satisfy only one or two of the above conditions (1) to (3). Even in this configuration, the first through-hole group G1 is located upstream of the flow of fuel gas FG in the fuel chamber 176 relative to the second through-hole group G2, and this makes it possible to more efficiently ensure both the bonding strength between the fuel electrode 116 and the metal support 180 and the power generation performance of the single cell 110 (and thus the power generation performance of the fuel cell stack 100) than in the past.

The method of selecting the plurality of through holes 50 formed in the metal support 180 to be divided into the first through hole group G1 and the second through hole group G2 is not limited to that of the above embodiment, and can be changed in various ways. For example, in the above embodiment, the first through hole group G1 is located upstream (positive Y-axis direction) of the flow of the fuel gas FG in the fuel chamber 176 with respect to the second through hole group G2, but the first through hole group G1 and the second through hole group G2 that are not in such a positional relationship may be adopted. Also, in the above embodiment, the number of through holes 50 included in the second through hole group G2 may be less than the number of through holes 50 included in the first through hole group G1, but may be more than the number of through holes 50 included in the first through hole group G1 (in other words, the number of through holes 50 included in the first through hole group G1 may be less than the number of through holes 50 included in the second through hole group G2). In this configuration, the number of through holes 50 included in the first through hole group G1 is smaller than the number of through holes 50 included in the second through hole group G2, so that the gas flow can be improved compared to a configuration in which the numbers of through holes 50 are the same. In addition, in the above embodiment, both the first through hole group G1 and the second through hole group G2 are composed of multiple through holes 50, but one or both of the first through hole group G1 and the second through hole group G2 may be composed of only one through hole 50.

In the above embodiment, the metal support 180 is composed of a first metal member 181 and a second metal member 182 stacked in the Z-axis direction, but the configuration of the metal support 180 is not limited to this. For example, the metal support 180 may be composed of one plate-shaped member, or may be composed of three or more plate-shaped members stacked in the Z-axis direction. Furthermore, when the metal support 180 is composed of multiple plate-shaped members stacked in the Z-axis direction, the thicknesses of the plate-shaped members may be the same as each other or may be different from each other.

In the above embodiment, the single cell 110 includes a metal support 180 located on the opposite side of the electrolyte layer 112 with respect to the fuel electrode 116, and satisfies the above specific condition (the length LJ1 in the Z-axis direction of the joint J1 at which the fuel electrode 116 in each through hole 50 included in the first through hole group G1 is joined to the surface defining the through hole 50 of the metal support 180 is shorter than the length LJ2 in the Z-axis direction of the joint J2 at which the fuel electrode 116 in each through hole 50 included in the second through hole group G2 is joined to the surface defining the through hole 50 of the metal support 180). Instead of or in addition to such a metal support 180, a configuration including an air electrode side metal support described later may be adopted. That is, the single cell 110 may include a metal support (hereinafter referred to as the "air electrode side metal support") located on the opposite side of the electrolyte layer 112 with respect to the air electrode 114, and may adopt a configuration that satisfies the same conditions as the above specific condition. In such a configuration, the gas flow through the through holes of the air electrode side metal support can be improved, thereby improving the power generation performance of the single cell 110. In this configuration, the air electrode 114 is an example of a specific electrode in the scope of the claims.

In the above embodiment, a reaction prevention layer may be disposed between the air electrode 114 and the electrolyte layer 112 of the single cell 110 to prevent 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 generate a highly resistive substance (e.g., SrZrO ₃ ). The reaction prevention layer is formed, for example, from a ceria-based ion conductor material.

In the above embodiment, the above-mentioned configuration does not necessarily need to be realized in all of the unit cells 110 included in the fuel cell stack 100, but it is sufficient that the above-mentioned configuration is realized in at least one unit cell 110 included in the fuel cell stack 100. For example, in the above embodiment, the configuration of the metal support 180 provided in each unit cell 110 is the same, but the configuration of the metal support provided in any unit cell may be different. Also, in the above embodiment, the configuration of the fuel electrode 116 provided in each unit cell 110 is the same, but the configuration of the fuel electrode provided in any unit cell may be different.

The materials constituting each component in the above embodiment are merely examples, and each component may be composed of other materials. Furthermore, the manufacturing method of the unit cell 110 in the above embodiment is merely an example, and various modifications are possible.

In the above embodiment, the subject is a solid oxide fuel cell (SOFC) that generates electricity by utilizing an electrochemical reaction between hydrogen contained in a fuel gas and oxygen contained in an oxidant gas. However, the technology disclosed in this specification can also be applied to an electrolysis cell stack including a plurality of electrolysis cell units, which are constituent units of a solid oxide electrolysis cell (SOEC) that generates hydrogen by utilizing an electrolysis reaction of water. The configuration of the electrolysis cell stack is publicly known, for example, as described in JP 2016-81813 A, and will not be described in detail here, but it is generally similar to the configuration of the fuel cell stack 100 in the above embodiment. That is, the fuel cell stack 100 in the above embodiment may be read as an electrolysis cell stack, the power generation unit 102 as an electrolysis cell unit, and the single cell 110 as an electrolysis single cell. However, when the electrolysis cell stack is operated, a voltage is applied between the electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and water vapor is supplied as a raw material gas through the through hole 108. As a result, a water electrolysis reaction occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is extracted to the outside of the electrolysis cell stack through the through hole 108. By adopting a configuration similar to that of the above embodiment, an electrolysis single cell having such a configuration can achieve the same effects as the above embodiment.

In the above embodiment, a solid oxide fuel cell (SOFC) is used as an example, but the technology disclosed in this specification can also be applied to other types of fuel cells (or electrolytic cells), such as a molten carbonate fuel cell (MCFC).

22 (22A to 22E): Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Main body 29: Branching portion 50: Through hole 51: First portion 52: Second portion 53: Opening 54: Opening 100: Fuel cell stack 102: Power generation unit 104, 106: End plate 108: Through hole 110: Single cell 110A: Single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 117: Base 118: Inside hole 118A: Inside hole 120: Separator 121: Hole 124: Joint 130: Air electrode side frame member 131: Hole 132: Air electrode side gas supply communication channel 133: Air electrode side gas exhaust communication channel 134: Air electrode side current collector 135: current collector element 140: fuel electrode side frame member 141: hole 142: fuel electrode side gas supply communication channel 143: fuel electrode side gas exhaust communication channel 144: fuel electrode side current collector 145: current collector element 150: interconnector 161: air electrode side gas supply manifold 162: air electrode side gas exhaust manifold 166: air chamber 171: fuel electrode side gas supply manifold 172: fuel electrode side gas exhaust manifold 176: fuel chamber 180: metal support 181: first metal member 182: second metal member FG: fuel gas FOG: fuel off-gas G1: first through-hole group G2: second through-hole group J1: joint J2: joint LJ1: length LJ2: length OG: oxidant gas OOG: oxidant off-gas P1: Porosity P2: Porosity S11: Top surface S12: Bottom surface S21: Top surface S22: Bottom surface SP: Space

Claims (5)

An electrolyte layer;
a fuel electrode and a cathode facing each other in a first direction with the electrolyte layer therebetween;
an electrochemical reaction unit cell comprising: a metal support positioned on the opposite side of the electrolyte layer with respect to a specific electrode, which is one of the fuel electrode and the air electrode, the metal support having a plurality of through holes penetrating in the first direction at a position overlapping with the specific electrode when viewed in the first direction, and the specific electrode being joined to a surface of the metal support that defines the through hole in at least one of the plurality of through holes;
When the plurality of through holes are divided into a first through hole group consisting of one or more of the through holes and a second through hole group consisting of one or more of the through holes,
a length in the first direction of a joint portion at which the specific electrode in the through hole included in the first through hole group is joined to a surface of the metal support that defines the through hole is shorter than a length in the first direction of a joint portion at which the specific electrode in the through hole included in the second through hole group is joined to a surface of the metal support that defines the through hole ,
The electrochemical reaction unit cell , wherein the first group of through holes and the second group of through holes are arranged in different regions. 2. The electrochemical reaction unit cell according to claim 1,
the number of the through holes included in the second through hole group is smaller than the number of the through holes included in the first through hole group;
Electrochemical reaction unit cell. 2. The electrochemical reaction unit cell according to claim 1,
the number of the through holes included in the first through hole group is smaller than the number of the through holes included in the second through hole group;
Electrochemical reaction unit cell. An electrolyte layer;
a fuel electrode and a cathode facing each other in a first direction with the electrolyte layer therebetween;
an electrochemical reaction unit cell comprising: a metal support positioned on the opposite side of the electrolyte layer with respect to a specific electrode, which is one of the fuel electrode and the air electrode, the metal support having a plurality of through holes penetrating in the first direction at a position overlapping with the specific electrode when viewed in the first direction, and the specific electrode being joined to a surface of the metal support that defines the through hole in at least one of the plurality of through holes;
When the plurality of through holes are divided into a first through hole group consisting of one or more of the through holes and a second through hole group consisting of one or more of the through holes,
a length in the first direction of a joint portion at which the specific electrode in the through hole included in the first through hole group is joined to a surface of the metal support that defines the through hole is shorter than a length in the first direction of a joint portion at which the specific electrode in the through hole included in the second through hole group is joined to a surface of the metal support that defines the through hole,
a porosity of a first portion of the specific electrode located within the through hole included in one of the first through hole group and the second through hole group is greater than a porosity of a second portion of the specific electrode located within the through hole included in the other of the first through hole group and the second through hole group;
Electrochemical reaction unit cell. An electrolyte layer;
a fuel electrode and a cathode facing each other in a first direction with the electrolyte layer therebetween;
an electrochemical reaction unit cell comprising: a metal support positioned on the opposite side of the electrolyte layer with respect to a specific electrode, which is one of the fuel electrode and the air electrode, the metal support having a plurality of through holes penetrating in the first direction at a position overlapping with the specific electrode when viewed in the first direction, and the specific electrode being joined to a surface of the metal support that defines the through hole in at least one of the plurality of through holes;
When the plurality of through holes are divided into a first through hole group consisting of one or more of the through holes and a second through hole group consisting of one or more of the through holes,
an electrochemical reaction cell stack including a plurality of electrochemical reaction units arranged side by side in the first direction, each of which has an electrochemical reaction unit cell and a gas chamber facing the specific electrode, the electrochemical reaction unit cell having a length in the first direction of a joint portion at which the specific electrode in the through hole included in the first through hole group and a surface of the metal support that defines the through hole being joined, the length in the first direction of a joint portion at which the specific electrode in the through hole included in the second through hole group and a surface of the metal support that defines the through hole being joined, the length in the first direction of a joint portion being shorter than a length in the first direction of a joint portion at which the specific electrode in the through hole included in the second through hole group and a surface of the metal support that defines the through hole being joined,
In at least one of the electrochemical reaction units, the first through-hole group is located upstream of the gas flow in the gas chamber with respect to the second through-hole group.
Electrochemical reaction cell stack comprising:

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