JP2023080459A - Electrochemical reaction cell stack - Google Patents

Abstract

To suppress performance degradation and occurrence of defects due to foreign matters mixed in a gas while suppressing increase in the number of components and increase in a stack size.SOLUTION: An electrochemical reaction cell stack includes a plurality of electrochemical reaction units each including a single cell. A manifold is formed in the electrochemical reaction cell stack, the manifold exchanging a gas with a specific electrode of each of the electrochemical reaction units. A communication channel for communicating between the manifold and the specific electrode is formed in each of the electrochemical reaction units. A specific area exists on a surface of a member that defines a gas channel comprising the manifold and the communication channel, the specific area being an area satisfying such conditions that (1) a plurality of grooves extending approximately parallel to a specific direction is formed, and (2) the maximum height Rz along a direction crossing the specific direction is 0.01 μm or more and 50 μm or less.SELECTED DRAWING: Figure 5

Description

The technology disclosed by this specification relates to an electrochemical reaction cell stack.

A solid oxide fuel cell (hereinafter referred to as "SOFC") is known as one type of fuel cell that generates power using an electrochemical reaction between hydrogen and oxygen. SOFCs are generally used in the form of a fuel cell stack in which a plurality of structural units (hereinafter referred to as "fuel cell power generation units" or "power generation units") are arranged side by side in a predetermined direction. Each power generation unit has a fuel cell single cell (hereinafter simply referred to as "single cell"). A single cell includes an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other in the predetermined direction with the electrolyte layer interposed therebetween. Hereinafter, the air electrode and the fuel electrode are collectively referred to as "electrodes".

The fuel cell stack is formed with a manifold for exchanging gas with the electrodes of each power generation unit. In addition, each power generation unit is formed with a communication flow path that connects the manifold and the electrode. Hereinafter, the manifold and the communication channel will be collectively referred to as "gas channel".

During the manufacturing and operation of the fuel cell stack, foreign matter derived from the members constituting the fuel cell stack may be generated, and during the operation of the fuel cell stack, the foreign matter may be mixed into the gas flowing through the gas flow path. . The size of such foreign matter is often 50 μm or less. If the gas flowing through the gas flow path is mixed with foreign matter, for example, the following phenomena may occur, and the performance of the fuel cell stack may deteriorate, or the system including the fuel cell stack may malfunction.
(1) A single cell is poisoned by a foreign matter adhering to the single cell.
(2) When foreign matter adheres to the single cell or other members, the temperature of the adhered portion rises abnormally, causing cracks or cracks in the single cell or other members, or producing reaction products that adversely affect performance. be formed.
(3) Deterioration of catalyst performance due to adhesion of foreign matter discharged from the fuel cell stack to the reforming catalyst and the combustion catalyst outside the fuel cell stack.
(4) Foreign matter discharged from the fuel cell stack deposits on fluid pipes, pumps, valves, and other auxiliary equipment outside the fuel cell stack, causing flow failures in the pipes and auxiliary equipment.

Conventionally, in a fuel cell stack, a non-power generating cell that does not contribute to power generation is provided, and an impurity removal flow path is formed in the non-power generating cell to remove impurities contained in the gas flowing through the fuel cell stack, and the impurity is used to generate power. A configuration for suppressing the flow into cells is known (see, for example, Patent Document 1).

Japanese Patent No. 4973500

In the conventional fuel cell stack configuration described above, it is necessary to provide non-power generating cells that do not contribute to power generation in order to remove foreign substances contained in the gas. There is a problem that it becomes longer in the direction.

In addition, such a subject is an electrolytic cell including an electrolytic single cell, which is a structural unit of a solid oxide type electrolytic cell (hereinafter referred to as "SOEC") that generates hydrogen using the electrolysis reaction of water. It is also a common problem for electrolysis cell stacks with multiple units. In this specification, the fuel cell single cell and the electrolysis single cell are collectively referred to as an electrochemical reaction single cell, the fuel cell power generation unit and the electrolysis cell unit are collectively referred to as an electrochemical reaction unit, and a fuel cell stack. The electrolysis cell stack is collectively called an electrochemical reaction cell stack. Moreover, such problems are not limited to SOFCs and SOECs, but are common to other types of fuel cells and electrolytic cells.

This specification discloses a technology capable of solving the above-described problems.

The technology disclosed in this specification can be implemented, for example, in the following forms.

(1) The electrochemical reaction cell stack disclosed in the present specification includes a plurality of electric cells each having an electrochemical reaction unit cell including an electrolyte layer, and an air electrode and a fuel electrode facing each other with the electrolyte layer interposed therebetween. Equipped with a chemical reaction unit. In the electrochemical reaction cell stack, a manifold is formed for exchanging gas between each specific electrode, which is at least one of the air electrode and the fuel electrode, and the specific electrode of each of the electrochemical reaction units. ing. Each of the electrochemical reaction units is formed with a communication channel that connects the manifold and the specific electrode. (1) a plurality of grooves extending substantially parallel to a specific direction are formed on a surface of a member that defines a gas flow path composed of the manifold and the communication flow path; There is a specific region that satisfies the condition that the maximum height Rz along the direction intersecting the specific direction is 0.01 μm or more and 50 μm or less.

As described above, in the present electrochemical reaction cell stack, the surface of the member defining the gas flow path composed of the manifold and the communication flow path has a specific region in which a plurality of grooves substantially parallel to a specific direction are formed. exist. Since the maximum height Rz along the direction crossing the specific direction (the direction substantially parallel to the extending direction of the plurality of grooves) in the specific region is 0.01 μm or more and 50 μm or less, the plurality of grooves in the specific region The size of the unevenness caused by the presence of is neither excessively small nor excessively large. Here, the size of the foreign matter mixed in the gas flowing through the gas flow path is often 50 μm or less, and the shape of the foreign matter is rarely a perfect sphere, and often has an irregular shape. Therefore, according to the present electrochemical reaction cell stack, even if a foreign substance is mixed in the gas flowing through the gas flow path, the unevenness present in a specific region on the surface of the member defining the gas flow path will cause , Ability to hook and trap irregularly shaped foreign objects. In addition, in this electrochemical reaction cell stack, it is not necessary to provide non-power generating cells that do not contribute to power generation in order to remove foreign substances mixed in the gas, so the number of parts and the size of the electrochemical reaction cell stack are reduced. Increase can be suppressed. Therefore, according to the present electrochemical reaction cell stack, it is possible to suppress an increase in the number of parts and an increase in the size of the electrochemical reaction cell stack, and to reduce the deterioration of the electrochemical reaction cell stack due to foreign matter mixed in the gas flowing through the gas flow path. It is possible to suppress the occurrence of system failures including performance degradation and electrochemical reaction cell stacks.

(2) In the above electrochemical reaction cell stack, the specific region may have a maximum height Rz of 0.1 μm or more along a direction intersecting the specific direction. According to the present electrochemical reaction cell stack, since the unevenness caused by the presence of the plurality of grooves in the specific region is large to some extent, foreign matter in the gas flowing through the manifold and the communication channel can be removed from the unevenness in the specific region of the surface of the gas channel. As a result, it is possible to effectively suppress the deterioration of the performance of the electrochemical reaction cell stack and the occurrence of malfunctions of the system including the electrochemical reaction cell stack due to the foreign matter. .

(3) In the above electrochemical reaction cell stack, the specific region may have a maximum height Rz of 20 μm or less along a direction intersecting the specific direction. According to this electrochemical reaction cell stack, since the unevenness caused by the presence of the plurality of grooves in the specific region is small to some extent, foreign matter in the gas flowing through the manifold and the communication channel can be removed from the unevenness in the specific region of the surface of the gas channel. It is possible to prevent the smooth gas flow in the gas flow path from being hindered due to the irregularities while realizing trapping by hooking.

(4) In the above electrochemical reaction cell stack, each of the electrochemical reaction units has a metal member including a metal base material and an oxide film formed on the surface of the base material, and the specific region is , may be present on the surface of the metal member. According to the present electrochemical reaction cell stack, the unevenness caused by the presence of the plurality of grooves in the specific region can be formed into a relatively sharp shape, and the unevenness effectively removes foreign matter mixed in the gas flowing through the gas flow path. As a result, it is possible to effectively suppress the deterioration of the performance of the electrochemical reaction cell stack and the occurrence of malfunctions of the system including the electrochemical reaction cell stack due to the foreign matter.

(5) In the above electrochemical reaction cell stack, the specific direction may be substantially parallel to the main flow direction of the gas at the position of the specific region. According to the present electrochemical reaction cell stack, it is possible to prevent the smooth gas flow in the gas flow path from being hindered due to the existence of the plurality of grooves in the specific region.

(6) In the above electrochemical reaction cell stack, the specific direction may be a direction substantially orthogonal to the main flow direction of the gas at the position of the specific region. According to the present electrochemical reaction cell stack, the unevenness caused by the presence of the plurality of grooves in the specific region can effectively hook and trap foreign matter mixed in the gas flowing through the gas flow channel. It is possible to effectively suppress the deterioration of the performance of the electrochemical reaction cell stack and the occurrence of troubles in the system including the electrochemical reaction cell stack.

(7) In the above electrochemical reaction cell stack, there are a plurality of the specific regions, and the specific direction in one of the specific regions is substantially parallel to the main flow direction of the gas at the position of the specific region. The specific direction in the other specific region may be a direction substantially perpendicular to the main flow direction of the gas at the position of the specific region. According to the present electrochemical reaction cell stack, it is possible to suppress obstruction of smooth gas flow in the gas flow path due to the presence of a plurality of grooves in one specific region, and at the same time, The irregularities resulting from the presence of the plurality of grooves can effectively hook and trap foreign matter mixed in the gas flowing through the gas flow path.

(8) In the electrochemical reaction cell stack, a supply side manifold for supplying gas and a discharge side manifold for discharging gas are formed as the manifolds, and each of the electrochemical reaction units is connected to the As flow paths, a supply-side communication flow path that communicates the supply-side manifold and the specific electrode, and a discharge-side communication flow path that communicates the discharge-side manifold and the specific electrode are formed. a surface of a member defining the gas flow path composed of the supply side manifold and the supply side communication flow path; and a member defining the gas flow path composed of the discharge side manifold and the discharge side communication flow path. It is also possible to adopt a configuration in which the specific region exists on both the surface of the According to this electrochemical reaction cell stack, on both the gas supply side and the gas discharge side, foreign matter mixed in the gas flowing through the gas flow path is trapped by the unevenness caused by the existence of the plurality of grooves in the specific region. Therefore, it is possible to effectively suppress the deterioration of the performance of the electrochemical reaction cell stack and the occurrence of malfunctions of the system including the electrochemical reaction cell stack due to the foreign matter regardless of the location where the foreign matter is generated.

The technology disclosed in this specification can be implemented in various forms. For example, an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack), manufacturing methods thereof, and the like.

1 is a perspective view showing the external configuration of a fuel cell stack 100 according to this embodiment; FIG. Explanatory drawing showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II in FIG. Explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. Explanatory drawing showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position IV-IV in FIG. Explanatory diagram showing the XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. Explanatory diagram showing the XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. Explanatory diagram showing the YZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. Explanatory diagram showing the XY cross-sectional configuration of the power generation unit 102 at the position of VIII-VIII in FIG. Explanatory diagram showing the XY cross-sectional configuration of the power generation unit 102 at the position of IX-IX in FIG. Explanatory diagram showing performance evaluation results Explanatory drawing showing the external configuration of a fuel cell stack 2002 as a modified example. Explanatory drawing showing the external configuration of a fuel cell stack 1100 as another modified example. Explanatory drawing showing the external configuration of a fuel cell stack 3100 as another modified example.

A. Embodiment:
A-1. composition:
(Configuration of fuel cell stack 100)
FIG. 1 is a perspective view showing the external configuration of the fuel cell stack 100 in this embodiment, and 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. 3 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. 1, and FIG. 4 is the YZ cross-sectional configuration of the fuel cell stack 100 at the position IV-IV in FIG. It is an explanatory diagram showing. Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for the sake of convenience, the positive Z-axis direction is referred to as the upward direction, and the negative Z-axis direction is referred to as the downward direction. may be installed. The same applies to FIG. 5 and subsequent figures.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cell power generation units (hereinafter simply referred to as "power generation units") 102, terminal separators 210, upper end plates 220, lower end plates 189, and a pair of terminal plates 410, 420, an insulating portion 200, and a pair of end plates 104, 106. The seven power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in this embodiment). One of the pair of terminal plates 410 and 420 (hereinafter referred to as "upper terminal plate 410") is located above an assembly (hereinafter referred to as "power generation block 103") composed of seven power generation units 102. The other of the pair of terminal plates 410 , 420 (hereinafter referred to as “lower terminal plate 420 ”) is arranged below the power generation block 103 . End separator 210 is positioned above upper terminal plate 410 and lower end plate 189 is positioned below lower terminal plate 420 . The insulating portion 200 is positioned above the terminal separator 210 . One of the pair of end plates 104, 106 (hereinafter referred to as "upper end plate 104") is arranged above the insulating portion 200, and the other of the pair of end plates 104, 106 (hereinafter referred to as "upper end plate 104") , referred to as “lower end plate 106 ”) are disposed below the lower end plate 189 . The pair of end plates 104 and 106 are arranged to sandwich the power generation block 103, the terminal separator 210, the lower end plate 189, the pair of terminal plates 410 and 420, and the insulating portion 200 from above and below.

As shown in FIGS. 1 and 4, each layer (the power generation block 103, the terminal separator 210, the lower end plate 189, the pair of terminal plates 410 and 420, and the insulating portion 200) constituting the fuel cell stack 100 rotates in the Z-axis direction. Holes penetrating vertically through each layer are formed in the vicinity of four corners of the outer periphery of the . Holes (screw holes) are formed through the upper end plate 104 in the vicinity of the four corners of the outer periphery around the Z-axis direction, and the lower end plate 106 near the four corners of the outer periphery of the lower end plate 106 around the Z-axis direction. A hole (screw hole) is formed through the . Corresponding holes formed in each layer communicate with each other in the vertical direction to form bolt holes 109 extending in the vertical direction. In the following description, the holes formed in each layer of the fuel cell stack 100 to constitute the bolt holes 109 may also be referred to as the bolt holes 109 .

A bolt 22 is inserted into each bolt hole 109 . The upper end of each bolt 22 is screwed into the threaded hole of the nut 24 through the hole of the upper end plate 104, and the lower end of each bolt 22 is screwed into the nut 24 through the hole of the lower end plate 106. screwed into the screw hole. Each layer of the fuel cell stack 100 is integrally fastened by the bolts 22 and nuts 24 configured in this way.

Further, as shown in FIGS. 1 to 3, each layer (each power generation unit 102, lower terminal plate 420, lower end plate 189, lower end plate 106) constituting the fuel cell stack 100 has peripheral edges around the Z-axis direction. is formed with four holes vertically penetrating each layer, and the corresponding holes formed in each layer communicate with each other in the vertical direction, extending vertically from the uppermost power generation unit 102 to the lower end plate 106 A communication hole 108 extending in the direction is formed. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 may also be referred to as the communication holes 108 . Hereinafter, among the communication holes 108 , the holes formed in the lower end plate 106 are particularly referred to as end through holes 107 .

As shown in FIGS. 1 and 2, in the vicinity of one side (one of the two sides parallel to the Y-axis, the side on the positive side of the X-axis) that constitutes the outer circumference of the fuel cell stack 100 around the Z-axis direction. One communication hole 108 is a gas flow path through which an oxidant gas OG is introduced from the outside of the fuel cell stack 100 and supplies the oxidant gas OG to an air chamber 166 of each power generation unit 102, which will be described later. One communication hole 108 that functions as a gas supply manifold 161 and is located near the side opposite to the side (the side on the negative side of the X axis among the two sides parallel to the Y axis) is connected to each power generation unit. It functions as an oxidant gas discharge manifold 162 that is a gas flow path for discharging the oxidant offgas OOG, which is the gas discharged from the air chamber 166 of the fuel cell stack 102 , to the outside of the fuel cell stack 100 . The oxidant gas supply manifold 161 and the oxidant gas discharge manifold 162 are gas flow paths for exchanging gas with the air electrode 114 (described later) of each power generation unit 102 . For example, air is used as the oxidant gas OG.

1 and 3, among the sides forming the outer circumference of the fuel cell stack 100 around the Z-axis direction, the vicinity of the side closest to the communication hole 108 functioning as the oxidant gas discharge manifold 162 described above. Another communication hole 108 located in the fuel cell stack 100 is a gas flow path for introducing the fuel gas FG from the outside of the fuel cell stack 100 and supplying the fuel gas FG to a fuel chamber 176 of each power generation unit 102, which will be described later. Another communication hole 108 located near the side closest to the communication hole 108 functioning as the gas supply manifold 171 and functioning as the oxidant gas supply manifold 161 described above discharges from the fuel chamber 176 of each power generation unit 102. It functions as a fuel gas discharge manifold 172 that is a gas flow path for discharging the fuel off-gas FOG, which is the gas that has been discharged, to the outside of the fuel cell stack 100 . The fuel gas supply manifold 171 and the fuel gas discharge manifold 172 are gas flow paths for exchanging gas with the fuel electrode 116 (described later) of each power generation unit 102 . As the fuel gas FG, for example, a hydrogen-rich gas obtained by reforming city gas is used. Also, hereinafter, the air chamber 166 and the fuel chamber 176 are collectively referred to as a "gas chamber".

As shown in FIGS. 1 to 3, the fuel cell stack 100 is provided with four gas passage members 27 . Each gas passage member 27 has a hollow cylindrical body portion 28 and a flange portion 29 . A gas through hole 26 is formed in the body portion 28 so as to penetrate vertically. One end (upper end) of the body portion 28 is connected to an end through hole 107 formed in the lower end plate 106 . Specifically, the upper end of the body portion 28 is inserted into the end through hole 107 and joined by welding, for example. The outer diameter and inner diameter of the upper end of the body portion 28 are smaller than the outer diameter and inner diameter of the other end (lower end) of the body portion 28 . The flange portion 29 is provided so as to protrude from the lower end side of the main body portion 28 in a surface direction (direction parallel to the XY plane) perpendicular to the vertical direction (Z-axis direction). The shape of the flange portion 29 when viewed in the vertical direction is substantially rectangular, and bolt holes 29A (see FIG. 1) are formed at each of the four corners. A bolt (not shown) for connecting the fuel cell stack 100 to an external device is inserted into each bolt hole 29A.

As shown in FIG. 2, the gas through-hole 26 of the gas passage member 27 arranged at the position of the oxidant gas supply manifold 161 communicates with the oxidant gas supply manifold 161, and is located at the position of the oxidant gas discharge manifold 162. The gas through-holes 26 of the gas passage member 27 arranged at 1 are in communication with the oxidizing gas discharge manifold 162 . Further, as shown in FIG. 3, the gas through hole 26 of the gas passage member 27 arranged at the position of the fuel gas supply manifold 171 communicates with the fuel gas supply manifold 171, and at the position of the fuel gas discharge manifold 172. The gas through holes 26 of the arranged gas passage member 27 communicate with the fuel gas discharge manifold 172 .

(Configuration of end plates 104, 106)
The pair of end plates 104 and 106 are plate-like members having a substantially rectangular outer shape when viewed in the Z-axis direction, and are made of a conductive material such as stainless steel. Holes 32 and 34 penetrating in the Z-axis direction are formed near the center of the pair of end plates 104 and 106, respectively. As viewed in the Z-axis direction, the inner peripheral lines of the holes 32, 34 formed in the pair of end plates 104, 106 respectively include at least a portion of each single cell 110, which will be described later. A compressive force in the Z-axis direction generated by fastening with each bolt 22 and nut 24 acts mainly on the peripheral edge portion of each power generation unit 102 (portion on the outer peripheral side from each unit cell 110 described later). The end plates 104 and 106 are each formed by pressing (bending) a single plate member.

As shown in FIGS. 2-4, the upper end plate 104 includes a planar portion 310 and a convex portion 320. As shown in FIG. The plane portion 310 is a flat portion along a surface direction (direction parallel to the XY plane) perpendicular to the Z-axis direction. Specifically, the shape of the planar portion 310 as viewed in the Z-axis direction is a rectangular frame shape as a whole. The holes forming the bolt holes 109 described above are formed in the peripheral edge portion of the flat portion 310 around the Z-axis direction. The convex portion 320 is a rib that protrudes upward from the flat portion 310 . The protrusion 320 has an outer protrusion 322 and an inner protrusion 324 . The outer convex portion 322 protrudes upward from the outer peripheral portion of the planar portion 310 . Outer convex portion 322 is formed along the entire circumference of the outer peripheral portion of flat portion 310 . The inner convex portion 324 protrudes upward from the inner peripheral portion of the flat portion 310 . The inner convex portion 324 is formed along the entire circumference of the inner peripheral portion of the planar portion 310 .

Also, the lower end plate 106 includes a flat portion 510 and a convex portion 520 . The plane portion 510 is a flat portion along a plane direction (direction parallel to the XY plane) perpendicular to the Z-axis direction. Specifically, the shape of the planar portion 510 as viewed in the Z-axis direction is a rectangular frame shape as a whole. In addition, the holes forming the bolt holes 109 described above are formed in the peripheral portion of the plane portion 510 around the Z-axis direction. The convex portion 520 is a rib projecting downward from the flat portion 510 . The convex portion 520 has an outer convex portion 522 and an inner convex portion 524 . The outer convex portion 522 protrudes downward from the outer peripheral portion of the flat portion 510 . Outer convex portion 522 is formed along the entire circumference of the outer peripheral portion of flat portion 510 . The inner convex portion 524 protrudes downward from the inner peripheral portion of the planar portion 510 . The inner convex portion 524 is formed along the entire circumference of the inner peripheral portion of the planar portion 510 .

As shown in FIGS. 2 and 3, a reinforcing member 600 is fixed to the lower end plate 106 . The reinforcing member 600 has a flat plate portion 610 and a tubular portion 620 . The flat plate portion 610 is a flat plate-like portion parallel to the flat portion 510 of the lower end plate 106 . The shape of the flat plate portion 610 when viewed in the up-down direction is substantially rectangular. The flat plate portion 610 is positioned at a position spaced downward from the flat portion 510 of the lower end plate 106 . One side in the longitudinal direction of the flat plate portion 610 is in contact with the inner wall surface of the outer convex portion 522 and is joined by, for example, welding. It contacts the inner wall surface and is joined by welding, for example. A through-hole 612 into which the body portion 28 of the gas passage member 27 can be inserted is formed in the flat plate portion 610 . The tubular portion 620 is a cylindrical portion having a through hole 622 that communicates with the through hole 612 of the flat plate portion 610 . Cylindrical portion 620 is formed to protrude downward from the peripheral portion of through hole 612 in flat plate portion 610 . The inner wall surfaces forming the through hole 612 of the flat plate portion 610 and the through hole 622 of the cylindrical portion 620 are in contact with the outer peripheral surface of the main body portion 28 of the gas passage member 27 and are joined by welding, for example. The flat plate portion 610 and the tubular portion 620 are integrally formed. The reinforcing member 600 is preferably made of a heat-resistant material, the same material as the lower end plate 106, the gas passage member 27, or the like, or a material having the same coefficient of thermal expansion. It is

(Configuration of Terminal Plates 410, 420)
The pair of terminal plates 410 and 420 are plate-like members having a substantially rectangular outer shape when viewed in the Z-axis direction, and are made of a conductive material such as stainless steel. A hole 412 is formed near the center of the upper terminal plate 410 so as to penetrate in the Z-axis direction. As viewed in the Z-axis direction, the inner peripheral line of the hole 412 formed in the upper terminal plate 410 includes each single cell 110 described later. As viewed in the Z-axis direction, one end (positive X-axis direction side) of each of the pair of terminal plates 410 and 420 protrudes laterally from the power generation block 103 . In this embodiment, the projecting portion of the upper terminal plate 410 functions as a positive output terminal of the fuel cell stack 100 , and the projecting portion of the lower terminal plate 420 functions as a negative output terminal of the fuel cell stack 100 . do.

(Configuration of upper end plate 220)
The upper end plate 220 is a plate-like member having a substantially rectangular outer shape when viewed in the Z-axis direction, and is made of a conductive material such as stainless steel. The upper end plate 220 is arranged above the power generation block 103 and is electrically connected to an interconnector 190 (described later) located at the upper end of the power generation block 103 . In this embodiment, the upper end plate 220 and the interconnector 190 are electrically connected via a connecting member having the same structure as the fuel electrode side collector member 144 described later.

(Structure of Terminal Separator 210)
The terminal separator 210 is a frame-shaped member having a substantially rectangular through-hole 211 penetrating vertically in the vicinity of the center thereof, and is made of metal, for example. A portion of the terminal separator 210 surrounding the through hole 211 (hereinafter referred to as a “through hole surrounding portion”) is joined to the upper surface of the peripheral portion of the upper end plate 220 by, for example, welding. The end separator 210 separates the space between the top plate 220 and the power generation block 103 and the space outside the fuel cell stack 100 .

The terminal separator 210 includes an inner portion 216 including the peripheral portion of the through hole of the terminal separator 210, an outer portion 217 located on the outer peripheral side of the inner portion 216, and a connecting portion 218 connecting the inner portion 216 and the outer portion 217. Prepare. In this embodiment, the inner portion 216 and the outer portion 217 are substantially flat plates extending in a direction substantially orthogonal to the Z-axis direction. Further, the connecting portion 218 has a curved shape that protrudes downward from both the inner portion 216 and the outer portion 217 . A lower portion (on the power generation block 103 side) of the connecting portion 218 is a convex portion, and an upper portion (on the upper end plate 104 side) of the connecting portion 218 is a concave portion. Therefore, the connecting portion 218 includes portions whose positions in the Z-axis direction are different from those of the inner portion 216 and the outer portion 217 .

(Configuration of lower end plate 189)
The lower end plate 189 is a flat member having a substantially rectangular outer shape when viewed in the Z-axis direction, and is made of an insulating material, for example. The peripheral edge of the lower end plate 189 is sandwiched between the lower terminal plate 420 and the lower end plate 106, thereby improving the sealing performance of the manifolds 161, 162, 171, 172 and the lower terminal plate 420. and insulation from the lower end plate 106 are ensured.

(Configuration of insulating portion 200)
The insulating portion 200 is a frame-shaped member having a substantially rectangular through hole penetrating vertically in the vicinity of the center thereof, and is made of, for example, an insulating material. The insulating portion 200 is sandwiched between the upper end plate 104 and the terminal separator 210 to provide sealing for each manifold 161 , 162 , 171 , 172 and insulation between the upper end plate 104 and the terminal separator 210 . is guaranteed.

(Configuration of power generation unit 102)
5 is an explanatory diagram showing the XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 2, and FIG. FIG. 7 is an explanatory diagram showing the XZ cross-sectional configuration of two power generation units 102, and FIG. 7 is an explanatory diagram showing the YZ cross-sectional configuration of two adjacent power generation units 102 at the same position as the cross section shown in FIG. 8 is an explanatory diagram showing the XY cross-sectional configuration of the power generation unit 102 at the position VIII-VIII in FIG. 5, and FIG. 9 is the XY cross-sectional configuration of the power generation unit 102 at the position IX-IX in FIG. It is an explanatory diagram showing.

As shown in FIGS. 5 to 7, the power generation unit 102 includes a fuel cell single cell (hereinafter referred to as "single cell") 110, a single cell separator 120, an air electrode side frame 130, and a fuel electrode side frame. 140 , a fuel electrode side collector member 144 , and a pair of interconnectors 190 and a pair of IC separators 180 that constitute the uppermost and lowermost layers of the power generation unit 102 . Communicating holes 108 functioning as manifolds 161, 162, 171, and 172 are formed in peripheral portions of the single cell separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the IC separator 180 around the Z-axis direction. Constituting holes and holes constituting each bolt hole 109 are formed.

The single cell 110 includes an electrolyte layer 112, an air electrode 114 arranged on one side (upper side) of the electrolyte layer 112 in the Z-axis direction, and an air electrode 114 arranged on the other side (lower side) of the electrolyte layer 112 in the Z-axis direction. It comprises an anode 116 and a reaction prevention layer 118 disposed between the electrolyte layer 112 and the cathode 114 . The single cell 110 of this embodiment is a fuel electrode supporting type single cell in which the fuel electrode 116 supports the other layers (electrolyte layer 112, air electrode 114, reaction prevention layer 118) that constitute the single cell 110. .

The electrolyte layer 112 is a substantially rectangular plate-shaped member when viewed in the Z-axis direction, and is configured to contain a solid oxide (for example, YSZ (yttria-stabilized zirconia)). That is, the single cell 110 of this embodiment is a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular plate-shaped member smaller than the electrolyte layer 112 when viewed in the Z-axis direction, and is configured to contain, for example, a perovskite oxide (for example, LSCF (lanthanum strontium cobalt iron oxide)). . The fuel electrode 116 is a substantially rectangular plate-shaped member having substantially the same size as the electrolyte layer 112 when viewed in the Z-axis direction, and is formed of, for example, Ni (nickel), a cermet made of Ni and ceramic particles, a Ni-based alloy, or the like. ing. The reaction prevention layer 118 is a substantially rectangular plate-shaped member having substantially the same size as the air electrode 114 when viewed in the Z-axis direction, and is configured to contain, for example, GDC (gadolinium-doped ceria). The reaction prevention layer 118 is formed by reacting an element (eg, Sr) diffused from the air electrode 114 with an element (eg, Zr) contained in the electrolyte layer 112 to generate a high-resistance substance (eg, SrZrO ₃ ). has the function of suppressing The air electrode 114 and the fuel electrode 116 are examples of specific electrodes in the claims.

The single-cell separator 120 is a frame-shaped member having a substantially rectangular through-hole 121 penetrating vertically in the vicinity of the center thereof, and is made of metal, for example. A portion of the single-cell separator 120 surrounding the through-hole 121 (hereinafter referred to as a “through-hole surrounding portion”) faces the upper surface of the peripheral portion of the single-cell 110 (electrolyte layer 112 ). The unit cell separator 120 is joined to the unit cell 110 (electrolyte layer 112) by a joining portion 124 formed of brazing material (for example, Ag brazing) arranged at the opposing portion. An air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the fuel electrode 116 are partitioned by the single cell separator 120, and gas flows from one electrode side to the other electrode side in the peripheral portion of the single cell 110. leak (cross leak) is suppressed.

The single cell separator 120 has an inner portion 126 including the peripheral portion of the through hole of the single cell separator 120, an outer portion 127 located outside the inner portion 126, and a connection connecting the inner portion 126 and the outer portion 127. and a portion 128 . In this embodiment, the inner portion 126 and the outer portion 127 are substantially flat plates extending in a direction substantially orthogonal to the Z-axis direction. Moreover, the connecting portion 128 has a curved shape that protrudes downward from both the inner portion 126 and the outer portion 127 . The lower side (fuel chamber 176 side) of connecting portion 128 is a convex portion, and the upper side (air chamber 166 side) portion of connecting portion 128 is a concave portion. Therefore, the connecting portion 128 includes portions whose positions in the Z-axis direction are different from those of the inner portion 126 and the outer portion 127 .

A glass seal portion 125 containing glass is arranged near the through hole 121 in the single cell separator 120 . The glass seal portion 125 is positioned on the air chamber 166 side with respect to the joint portion 124, and the surface of the unit cell separator 120 around the through hole and the surface of the unit cell 110 (the electrolyte layer 112 in this embodiment) is formed to contact both the The glass seal portion 125 effectively suppresses gas leak (cross leak) from one electrode side to the other electrode side in the peripheral portion of the unit cell 110 .

The interconnector 190 is a conductive member having a substantially rectangular flat plate-shaped flat plate portion 150 and a plurality of substantially columnar air electrode side current collectors 134 projecting from the flat plate portion 150 toward the air electrode 114 side. (for example, ferritic stainless steel). In this embodiment, the surface of the interconnector 190 (the surface facing the air chamber 166) is formed with a conductive coating layer 194 made of, for example, spinel oxide. Below, the interconnector 190 covered with the covering layer 194 is simply referred to as the interconnector 190 . The interconnector 190 (each air electrode-side current collector 134 thereof) is joined to the air electrode 114 of the unit cell 110 via a conductive joint material 196 made of, for example, spinel oxide. It is electrically connected to the cathode 114 of the cell 110 . The interconnector 190 ensures electrical continuity between the power generation units 102 and suppresses mixing of reaction gases between the power generation units 102 . In addition, in this embodiment, when two power generation units 102 are arranged adjacently, one interconnector 190 is shared by the two adjacent power generation units 102 . That is, the upper interconnector 190 in one power generation unit 102 is the same member as the lower interconnector 190 in another power generation unit 102 adjacent to the upper side of the power generation unit 102 . In addition, since the fuel cell stack 100 has the lower terminal plate 420 and the lower end plate 189, the lowermost power generation unit 102 in the fuel cell stack 100 does not have the lower interconnector 190 (FIG. 2). to Figure 4).

The IC separator 180 is a frame-shaped member having a substantially rectangular through-hole 181 extending vertically through the vicinity of the center thereof, and is made of metal, for example. A portion of the IC separator 180 surrounding the through-hole 181 (hereinafter referred to as “through-hole surrounding portion”) is joined to the upper surface of the periphery of the flat plate portion 150 of the interconnector 190 by, for example, welding. Among the pair of IC separators 180 included in a certain power generation unit 102, the upper IC separator 180 is connected to the air chamber 166 of the power generation unit 102 and the other power generation unit 102 adjacent to the power generation unit 102 on the upper side. and the fuel chamber 176 of the . Also, of the pair of IC separators 180 included in a certain power generation unit 102, the lower IC separator 180 is adjacent to the fuel chamber 176 of the power generation unit 102 and the power generation unit 102 on the lower side. and the air chamber 166 of the power generation unit 102 . In this manner, the IC separator 180 suppresses gas leakage between the power generation units 102 at the periphery of the power generation units 102 . Note that the IC separator 180 joined to the upper interconnector 190 of the power generation unit 102 located at the uppermost position in the fuel cell stack 100 is electrically connected to the upper terminal plate 410 .

The IC separator 180 has an inner portion 186 including the peripheral portion of the through hole of the IC separator 180, an outer portion 187 located outside the inner portion 186, and a connecting portion 188 connecting the inner portion 186 and the outer portion 187. and In this embodiment, the inner portion 186 and the outer portion 187 are substantially flat plates extending in a direction substantially orthogonal to the Z-axis direction. Moreover, the connecting portion 188 has a curved shape that protrudes downward from both the inner portion 186 and the outer portion 187 . The lower side (air chamber 166 side) of the connecting portion 188 is a convex portion, and the upper side (fuel chamber 176 side) portion of the connecting portion 188 is a concave portion. Therefore, the connecting portion 188 includes portions whose positions in the Z-axis direction are different from those of the inner portion 186 and the outer portion 187 .

As shown in FIG. 8, the air electrode side frame 130 is a frame-shaped member having a substantially rectangular hole 131 extending in the Z-axis direction near the center, and is made of an insulator such as mica. there is A hole 131 in the cathode-side frame 130 constitutes an air chamber 166 facing the cathode 114 . The air electrode side frame 130 is in contact with the upper surface of the periphery of the single cell separator 120 and the lower surface of the periphery of the upper IC separator 180, and the gas sealing property ( That is, it functions as a sealing member that secures the gas sealing property of the air chamber 166 . Also, the cathode-side frame 130 electrically insulates between the pair of IC separators 180 included in the power generation unit 102 (that is, between the pair of interconnectors 190). The air electrode side frame 130 also has an oxidizing gas supply communication hole 132 that communicates the oxidizing gas supply manifold 161 and the air chamber 166, and an oxidizing gas supply communication hole 132 that communicates the air chamber 166 and the oxidizing gas discharge manifold 162. A discharge communication hole 133 is formed.

As shown in FIG. 9, the fuel electrode-side frame 140 is a frame-shaped member having a substantially rectangular hole 141 penetrating in the Z-axis direction near the center, and is made of metal, for example. A hole 141 in the anode-side frame 140 constitutes a fuel chamber 176 facing the anode 116 . The fuel electrode-side frame 140 is in contact with the lower surface of the periphery of the single cell separator 120 and the upper surface of the periphery of the lower IC separator 180 . Further, the fuel electrode side frame 140 has a fuel gas supply communication hole 142 that communicates the fuel gas supply manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that communicates the fuel chamber 176 and the fuel gas discharge manifold 172. and are formed.

As shown in FIGS. 5 to 7 , the fuel electrode side collector member 144 is arranged inside the fuel chamber 176 . The fuel electrode-side current collecting member 144 includes an interconnector-facing portion 146, an electrode-facing portion 145, and a connecting portion 147 that connects the electrode-facing portion 145 and the interconnector-facing portion 146, and is made of, for example, nickel or a nickel alloy. , stainless steel or the like. The electrode facing portion 145 is in contact with the lower surface of the fuel electrode 116 , and the interconnector facing portion 146 is in contact with the upper surface of (the flat plate portion 150 of) the interconnector 190 . However, as described above, since the lowermost power generation unit 102 in the fuel cell stack 100 does not have the lower interconnector 190, the fuel electrode side current collecting member 144 of the power generation unit 102 faces the interconnector. Portion 146 contacts lower terminal plate 420 . Fuel electrode side current collecting member 144 having such a configuration electrically connects fuel electrode 116 and interconnector 190 (or lower end plate 189). A spacer 149 made of mica, for example, is arranged between the electrode facing portion 145 and the interconnector facing portion 146 of the fuel electrode side collector member 144 . Therefore, the fuel electrode side current collecting member 144 follows the deformation of the power generation unit 102 due to the temperature cycle and reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 190 (or the lower terminal plate) via the fuel electrode side current collecting member 144. 420) is well maintained. The fuel electrode side collector member 144 is, for example, a sheet-shaped material (for example, a nickel foil with a thickness of 10 to 200 μm) with a plurality of rectangular cuts and a plurality of holes formed on the material. In the state where the fuel electrode side current collecting member 144 is arranged, a plurality of rectangular portions are bent and processed so as to sandwich the spacer 149 . Each bent rectangular portion becomes an electrode facing portion 145, and a flat plate portion with a hole other than the bent and raised portion becomes an interconnector facing portion 146, which connects the electrode facing portion 145 and the interconnector facing portion 146. A portion becomes the connecting portion 147 .

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 5, the oxidant gas OG is supplied through a gas pipe (not shown) connected to the body portion 28 of the gas passage member 27 provided at the position of the oxidant gas supply manifold 161. Then, the oxidizing gas OG is supplied to the oxidizing gas supply manifold 161 through the gas through holes 26 of the gas passage member 27, and from the oxidizing gas supply manifold 161 to the oxidizing gas supply communication holes of each power generation unit 102. 132 to air chamber 166 . 3 and 6, the fuel gas FG is supplied through a gas pipe (not shown) connected to the body portion 28 of the gas passage member 27 provided at the position of the fuel gas supply manifold 171. Then, the fuel gas FG is supplied to the fuel gas supply manifold 171 through the gas through hole 26 of the gas passage member 27, and from the fuel gas supply manifold 171 through the fuel gas supply communication hole 142 of each power generation unit 102. , are supplied to the fuel chamber 176 .

When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, electric power is generated in the single cell 110 by the electrochemical reaction of the oxidant gas OG and the fuel gas FG. will be This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the unit cell 110 is electrically connected to the upper interconnector 190, and the fuel electrode 116 is connected to the lower interconnector 190 (or the lower plate 189). That is, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. The upper interconnector 190 and the IC separator 180 of the uppermost power generation unit 102 are electrically connected to the upper terminal plate 410, and the lowermost power generation unit 102 is connected to the fuel electrode side. A lower terminal plate 420 is electrically connected to the electrical member 144 . Therefore, the electrical energy generated in each power generation unit 102 is taken out from terminal plates 410 and 420 that function as output terminals of fuel cell stack 100 . Since the SOFC generates power at a relatively high temperature (for example, 600° C. to 1000° C.), the fuel cell stack 100 is heated by the heater ( (not shown).

As shown in FIGS. 2 and 5, the oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 to the oxidant gas discharge manifold 162 through the oxidant gas discharge communication hole 133 is discharged into the oxidant gas discharge manifold. The gas is discharged to the outside of the fuel cell stack 100 via a gas pipe (not shown) connected to the main body 28 through the gas through hole 26 of the main body 28 of the gas passage member 27 provided at the position 162. be. Further, as shown in FIGS. 3 and 6, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 to the fuel gas discharge manifold 172 through the fuel gas discharge communication hole 143 is The gas is discharged to the outside of the fuel cell stack 100 via a gas pipe (not shown) connected to the main body 28 through the gas through hole 26 of the main body 28 of the gas passage member 27 provided at the position.

In the fuel cell stack 100 of the present embodiment, in each power generation unit 102, the main flow direction of the oxidant gas OG in the air chamber 166 (the direction from the positive direction of the X axis to the negative direction of the X axis) This is a counter-flow type SOFC in which the main flow direction of the gas FG (the direction from the negative direction of the X axis to the positive direction of the X axis) is substantially opposite (directions facing each other).

A-3. Detailed configuration of the gas flow path:
Next, the detailed configuration of the gas flow path in the fuel cell stack 100 of this embodiment will be described. The gas flow path referred to here is a gas flow path composed of each manifold and each communication flow path. It should be noted that the manifold includes flow paths formed in the gas passage member 27 . For example, the manifold on the air electrode side supply side is composed of an oxidant gas supply manifold 161 and a flow path formed in the gas passage member 27 arranged at the position of the oxidant gas supply manifold 161 . The air electrode side discharge side manifold, the fuel electrode side supply side manifold, and the fuel electrode side discharge side manifold are similarly provided with the oxidizing gas discharge manifold 162, the fuel gas supply manifold 171 and the fuel gas discharge manifold, respectively. 172 and flow paths formed in the gas passage members 27 arranged at respective positions. The communication channel is a channel that communicates the manifold and the electrode, and includes a communication hole that communicates the manifold and the gas chamber, a portion of the gas chamber (a portion located between the communication hole and the electrode), consists of For example, the supply-side communication channel on the air electrode side is a channel that communicates the oxidizing gas supply manifold 161 and the air electrode 114, and communicates the oxidizing gas supply manifold 161 with the air chamber 166. The communication hole 132 and a portion of the air chamber 166 located between the oxygen-containing gas supply communication hole 132 and the air electrode 114 . Similarly, the discharge-side communication passage on the air electrode side includes the oxidizing gas discharge communication hole 133 that communicates between the oxidizing gas discharge manifold 162 and the air chamber 166, and the oxidizing gas discharge communication hole 133 and the air in the air chamber 166. and a portion located between the pole 114 . The supply-side communication passage on the fuel electrode side includes a fuel gas supply communication hole 142 that communicates between the fuel gas supply manifold 171 and the fuel chamber 176, and a connection between the fuel gas supply communication hole 142 in the fuel chamber 176 and the fuel electrode 116. and a portion located between the fuel electrode side discharge side communication passage is composed of a fuel gas discharge communication hole 143 that communicates between the fuel gas discharge manifold 172 and the fuel chamber 176, and a fuel gas discharge in the fuel chamber 176. and a part located between the communication hole 143 and the fuel electrode 116 .

In the fuel cell stack 100 of the present embodiment, a specific area SA satisfying the following conditions (1) and (2) is formed on the surface of the member defining the gas flow path (the surface facing the gas flow path). exist.
(1) A plurality of grooves 11 extending substantially parallel to a specific direction are formed, and
(2) A maximum height Rz along a direction intersecting the specific direction is 0.01 μm or more and 50 μm or less.

In this specification, two directions being substantially parallel means that the angle formed by the two directions is 10 degrees or less. Therefore, the above condition (1) is not limited to the form in which the plurality of grooves 11 are parallel to each other, but the extending directions of the plurality of grooves 11 are slightly deviated from the state in which they are parallel to each other, and the plurality of grooves 11 intersect each other. Also includes forms that are

Further, the maximum height Rz in the above condition (2) is an index value of surface roughness defined in JIS B0601. The maximum height Rz can be measured with a non-contact or contact surface roughness meter. The maximum height Rz in the above condition (2) is the maximum height Rz along the direction crossing a specific direction (the direction substantially parallel to the extending direction of the plurality of grooves 11). It can be said that it is an index value representing the degree of unevenness on the surface caused by the existence of the surface. In addition, the "direction intersecting the specific direction" in the above condition (2) is, for example, a direction orthogonal to the specific direction.

The specific area SA that satisfies the above conditions (1) and (2) can be realized by forming a plurality of grooves 11 on the target member by, for example, polishing, laser processing, etching, or the like. Further, such a forming process of the grooves 11 may be performed on the forming material of the target member, or may be performed after processing the forming material to fabricate the target member.

As shown in FIG. 5, in the fuel cell stack 100 of the present embodiment, a specific area SA exists on the surface of the member that defines the oxidizing gas discharge manifold 162 as part of the gas flow path described above. The surfaces of the members defining the oxidizing gas discharge manifold 162 are specifically the single cell separator 120, the air electrode side frame 130, the fuel electrode side frame 140, the IC separator 180, the lower terminal plate 420, It is the inner peripheral surface of the communication hole 108 in the lower end plate 189 and the lower end plate 106 . The same applies to the surfaces of the members defining the oxidant gas supply manifold 161, the fuel gas discharge manifold 172, and the fuel gas supply manifold 171, which will be described later. In this embodiment, substantially the entire surface of the member that defines the oxidizing gas discharge manifold 162 is the specific area SA. The "specific direction" in the above condition (1) regarding the specific area SA on the surface of the member defining the oxidant gas discharge manifold 162 is the main flow direction of the gas (oxidant off-gas OOG) at the position of the specific area SA ( In this embodiment, the direction is substantially parallel to the Z-axis direction). That is, in this specific area SA, a plurality of grooves 11 extending substantially parallel to the main flow direction (Z-axis direction) of the oxidant offgas OOG are formed.

In addition, although not shown, in the fuel cell stack 100 of the present embodiment, the surface of the member defining the oxidant gas supply manifold 161 as part of the gas flow path described above also has a specific area SA. . In this embodiment, substantially the entire surface of the member that defines the oxidant gas supply manifold 161 is the specific area SA. The "specific direction" in the above condition (1) regarding the specific area SA on the surface of the member defining the oxidant gas supply manifold 161 is the main flow direction (oxidant gas OG) of the gas (oxidant gas OG) at the position of the specific area SA In this embodiment, the direction is substantially parallel to the Z-axis direction). That is, a plurality of grooves 11 extending substantially parallel to the main flow direction (Z-axis direction) of the oxidant gas OG are formed in the specific area SA.

As shown in FIG. 6, in the fuel cell stack 100 of the present embodiment, the surface of the member defining the fuel gas discharge manifold 172 as part of the gas flow path described above also has a specific area SA. . In this embodiment, substantially the entire surface of the member that defines the fuel gas discharge manifold 172 is the specific area SA. The “specific direction” in the above condition (1) regarding the specific area SA on the surface of the member defining the fuel gas discharge manifold 172 is the main flow direction of the gas (fuel off-gas FOG) at the position of the specific area SA (this embodiment In the form, the direction is substantially parallel to the Z-axis direction). That is, in this specific area SA, a plurality of grooves 11 extending substantially parallel to the main flow direction (Z-axis direction) of the fuel offgas FOG are formed.

Moreover, although not shown, in the fuel cell stack 100 of the present embodiment, the surface of the member defining the fuel gas supply manifold 171 as part of the gas flow path also has a specific area SA. In this embodiment, substantially the entire surface of the member that defines the fuel gas supply manifold 171 serves as the specific area SA. The “specific direction” in the above condition (1) regarding the specific area SA on the surface of the member defining the fuel gas supply manifold 171 is the main flow direction of the gas (fuel gas FG) at the position of the specific area SA (this embodiment In the form, the direction is substantially parallel to the Z-axis direction). That is, in this specific area SA, a plurality of grooves 11 extending substantially parallel to the main flow direction (Z-axis direction) of the fuel gas FG are formed.

For each of the oxidizing gas supply manifold 161, the oxidizing gas discharge manifold 162, the fuel gas supply manifold 171, and the fuel gas discharge manifold 172, in addition to the surface of the member that defines each manifold 161, 162, 171, 172, Alternatively, instead of the surface, the specific area SA may exist on the surface of the member defining the flow path formed in the gas passage member 27 arranged at the position of each of the manifolds 161, 162, 171, 172. .

Further, as shown in FIGS. 5 and 8, in the fuel cell stack 100 of the present embodiment, the surfaces of the members defining the air electrode side supply side and discharge side communication passages as part of the gas passages described above are also has a specific area SA. As described above, the supply-side communication passage on the air electrode side includes the oxidizing gas supply communication hole 132 that communicates between the oxidizing gas supply manifold 161 and the air chamber 166, and the oxidizing gas supply communication hole 132 in the air chamber 166. and a portion located between the air electrode 114 . In addition, the discharge-side communication passage on the air electrode side includes the oxidizing gas discharge communication hole 133 that communicates the oxidizing gas discharge manifold 162 and the air chamber 166, and the oxidizing gas discharge communication hole 133 in the air chamber 166 and the air electrode. and a portion located between 114 and . Therefore, the specific area SA includes at least one of the air electrode-side frame 130, the unit cell separator 120, the IC separator 180, and the interconnector 190, which are members that define the supply side and discharge side communication channels on the air electrode side. exist on one surface. In this embodiment, substantially the entire surface of the member defining the supply-side and discharge-side communication channels on the air electrode side is the specific area SA.

As shown in FIG. 8, the surface of the air electrode side frame 130 (the inner circumference of the oxidizing gas discharge communication hole 133) as a member defining the oxidant gas discharge communication hole 133 that constitutes the air electrode side discharge side communication flow path. The “specific direction” in the above condition (1) regarding the specific area SA existing in the surface) is the main flow direction (X-axis direction in this embodiment) of the gas (oxidant off-gas OOG) at the position of the specific area SA. is a direction substantially perpendicular to the That is, in this specific area SA, a plurality of grooves 11 extending in a direction substantially perpendicular to the main flow direction (X-axis direction) of the oxidant offgas OOG are formed. In this specification, two directions are substantially orthogonal to each other means that the angle formed by the two directions is within the range of 90°±10°. Although not shown, on the surface of the air electrode side frame 130 (inner peripheral surface of the oxidant gas supply communication hole 132) as a member defining the oxidant gas supply communication hole 132 constituting the supply side communication passage on the air electrode side, The same applies to the existing specific area SA.

Further, as shown in FIG. 8, the air is present on the surface (inner peripheral surface of the hole 131) of the air electrode side frame 130 as a member that defines a part of the air chamber 166 that constitutes the supply side communication passage on the air electrode side. The "specific direction" in the above condition (1) regarding the specific area SA is substantially orthogonal to the main flow direction (the X-axis direction in this embodiment) of the gas (oxidant gas OG) at the position of the specific area SA. is the direction. That is, a plurality of grooves 11 extending in a direction substantially perpendicular to the main flow direction (X-axis direction) of the oxidant gas OG are formed in the specific area SA. Although not shown, a specific area SA existing on the surface (inner peripheral surface of the hole 131) of the air electrode side frame 130 as a member defining a part of the air chamber 166 constituting the discharge side communication passage on the air electrode side The same is true for

Further, as shown in FIG. 5, the surface (upper surface) of the single cell separator 120 as a member defining a part of the oxidant gas supply communication hole 132 and the air chamber 166 constituting the supply side communication passage on the air electrode side (upper surface). ), the “specific direction” in the above condition (1) regarding the specific area SA existing in the specific area SA is in the main flow direction (the X-axis direction in this embodiment) of the gas (oxidant gas OG) at the position of the specific area SA. It is a substantially parallel direction. That is, a plurality of grooves 11 extending in a direction substantially parallel to the main flow direction (X-axis direction) of the oxidant gas OG are formed in the specific area SA. Although not shown, the oxidizing gas discharge communication hole 133 and the air chamber 166 constituting the air electrode side discharge side communication passage are provided on the surface (upper surface) of the single cell separator 120 as a member that defines a part of the air chamber 166. The same applies to area SA. Although not shown, surfaces (lower surfaces) of the IC separator 180 and the interconnector 190 serving as members defining a part of the oxidant gas supply communication hole 132 and the air chamber 166 constituting the supply side communication passage on the air electrode side are shown. ), and the IC separator 180 and the interconnector 190 as members defining a part of the oxidizing gas discharge communication hole 133 and the air chamber 166 that constitute the discharge side communication channel on the air electrode side. The same applies to the specific area SA existing on the surface (lower surface) of the .

Further, as shown in FIGS. 6 and 9, in the fuel cell stack 100 of the present embodiment, the surfaces of the members that define the supply side and discharge side communication passages on the fuel electrode side as part of the gas flow passages described above. also has a specific area SA. As described above, the supply-side communication passage on the fuel electrode side includes the fuel gas supply communication hole 142 that communicates the fuel gas supply manifold 171 and the fuel chamber 176, and the fuel gas supply communication hole 142 in the fuel chamber 176 and the fuel electrode. and a portion located between 116 and . Further, the discharge side communication passage on the fuel electrode side includes a fuel gas discharge communication hole 143 that communicates between the fuel gas discharge manifold 172 and the fuel chamber 176, and a connection between the fuel gas discharge communication hole 143 in the fuel chamber 176 and the fuel electrode 116. and a portion located in between. Therefore, the specific area SA includes at least one of the fuel electrode frame 140, the IC separator 180, the interconnector 190, and the single cell separator 120, which are members that define the supply side and discharge side communication channels on the fuel electrode side. exist on one surface. In this embodiment, substantially the entire surface of the member that defines the supply-side and discharge-side communication passages on the fuel electrode side serves as the specific area SA.

As shown in FIG. 9, the surface of the fuel electrode side frame 140 (the inner peripheral surface of the fuel gas discharge communication hole 143) as a member defining the fuel gas discharge communication hole 143 that constitutes the discharge side communication passage on the fuel electrode side. The "specific direction" in the above condition (1) regarding the specific area SA existing in the direction. That is, in this specific area SA, a plurality of grooves 11 extending in a direction substantially perpendicular to the main flow direction (X-axis direction) of the fuel offgas FOG are formed. Although not shown, it exists on the surface (inner peripheral surface of the fuel gas supply communication hole 142) of the fuel electrode side frame 140 as a member that defines the fuel gas supply communication hole 142 that constitutes the supply side communication passage on the fuel electrode side. The same applies to the specific area SA.

Further, as shown in FIG. 9, the fuel is present on the surface (inner peripheral surface of the hole 141) of the fuel electrode side frame 140 as a member that defines a part of the fuel chamber 176 that constitutes the supply side communication passage on the fuel electrode side. The “specific direction” in the above condition (1) regarding the specific area SA is a direction substantially orthogonal to the main flow direction (X-axis direction in this embodiment) of the gas (fuel gas FG) at the position of the specific area SA. is. That is, a plurality of grooves 11 extending in a direction substantially orthogonal to the main flow direction (X-axis direction) of the fuel gas FG are formed in the specific area SA. Although not shown, the specific area SA existing on the surface (inner peripheral surface of the hole 141) of the fuel electrode side frame 140 as a member defining a part of the fuel chamber 176 constituting the fuel electrode side discharge side communication passage. The same is true for

Further, as shown in FIG. 6, surfaces of an IC separator 180 and an interconnector 190 as members defining a part of the fuel gas supply communication hole 142 and the fuel chamber 176 constituting the supply side communication passage on the fuel electrode side are shown. The "specific direction" in the above condition (1) regarding the specific area SA existing on the (upper surface) is the main flow direction of the gas (fuel gas FG) at the position of the specific area SA (the X-axis direction in this embodiment). is a direction substantially parallel to . That is, a plurality of grooves 11 extending in a direction substantially parallel to the main flow direction (X-axis direction) of the fuel gas FG are formed in this specific area SA. Although not shown, it exists on the surfaces (upper surfaces) of the IC separator 180 and the interconnector 190 as members that define a part of the fuel gas discharge communication hole 143 and the fuel chamber 176 that constitute the discharge side communication passage on the fuel electrode side. The same applies to the specific area SA. Although not shown, the gas is present on the surface (lower surface) of the unit cell separator 120 as a member that defines a part of the fuel gas supply communication hole 142 and the fuel chamber 176 that constitute the supply side communication passage on the fuel electrode side. Exists on the surface (lower surface) of the single cell separator 120 as a member that defines a part of the specific area SA, the fuel gas discharge communication hole 143 and the fuel chamber 176 that constitute the discharge side communication passage on the fuel electrode side. The same applies to the specific area SA.

In addition, when the member defining the gas flow path described above is a metal member including a metal base material and an oxide film formed on the surface of the base material, the specific area SA is defined by the metal member. It exists on the surface (that is, on the surface of the oxide film). As such a metal member, for example, an interconnector including a flat plate portion 150 and an air electrode side collector portion 134 as a metal base material, and a coating layer 194 as an oxide film formed on the surface of the base material. 190 can be mentioned. Further, the oxide film includes an oxide film (for example, a chromia film or an alumina film) naturally formed on the surface of the metal base material.

A-4. Effect of this embodiment:
As described above, the fuel cell stack 100 of this embodiment includes a plurality of power generation units 102 each having a single cell 110 . A single cell 110 includes an electrolyte layer 112, and an air electrode 114 and a fuel electrode 116 facing each other with the electrolyte layer 112 interposed therebetween. The fuel cell stack 100 includes manifolds (an oxidant gas supply manifold 161, an oxidant gas discharge manifold 162, a fuel gas supply manifold 161, an oxidant gas discharge manifold 162, and a fuel gas supply manifold for exchanging gas between the electrodes (air electrode 114 or fuel electrode 116) of each power generation unit 102. A manifold 171 and a fuel gas discharge manifold 172) are formed. Each power generation unit 102 has a communication channel (an oxidant gas supply communication hole 132, an oxidant gas discharge communication hole 133, an oxidant gas supply communication hole 132 or an oxidant gas discharge communication hole 133) that communicates a manifold and an electrode. Part of air chamber 166 located between air electrode 114, fuel gas supply passage 142, fuel gas discharge passage 143, fuel gas supply passage 142 or fuel gas discharge passage 143 and fuel electrode 116 portion of the fuel chamber 176 located there) is formed. On the surface of the member defining the gas flow path composed of the manifold and the communication flow path in the fuel cell stack 100,
(1) A plurality of grooves 11 extending substantially parallel to a specific direction are formed, and
(2) the maximum height Rz along the direction intersecting the specific direction is 0.01 μm or more and 50 μm or less;
There is a specific area SA which is an area that satisfies the following condition.

As described above, in the fuel cell stack 100 of the present embodiment, a plurality of grooves 11 substantially parallel to a specific direction are formed on the surface of the member that defines the gas flow path composed of the manifold and the communication flow path. A specific area SA exists. Since the maximum height Rz along the direction crossing the specific direction (the direction substantially parallel to the extending direction of the plurality of grooves 11) in the specific area SA is 0.01 μm or more and 50 μm or less, in the specific area SA The size of the irregularities resulting from the presence of the plurality of grooves 11 is neither excessively small nor excessively large. Here, the size of the foreign matter mixed in the gas flowing through the gas flow path is often 50 μm or less, and the shape of the foreign matter is rarely a perfect sphere, and often has an irregular shape. Therefore, according to the fuel cell stack 100 of the present embodiment, even if foreign matter is mixed in the gas flowing through the gas flow path, the excessively small or large amount of foreign matter existing in the specific area SA on the surface of the member defining the gas flow path can be prevented. Due to the unevenness, irregularly shaped foreign matter can be hooked and trapped. In addition, in the fuel cell stack 100 of the present embodiment, it is not necessary to provide a non-power generating cell that does not contribute to power generation in order to remove foreign substances mixed in the gas. can be suppressed. Therefore, according to the fuel cell stack 100 of the present embodiment, while suppressing an increase in the number of parts and an increase in the size of the fuel cell stack 100, the deterioration of the fuel cell stack 100 due to foreign matter mixed in the gas flowing through the gas flow path can be prevented. It is possible to suppress the occurrence of performance deterioration and malfunction of the system including the fuel cell stack 100 .

In addition, in the fuel cell stack 100 of the present embodiment, each power generation unit 102 includes a metal base material (for example, the flat plate portion 150 and the air electrode side current collector 134) and an oxide film formed on the surface of the base material. (for example, a coating layer 194 and an oxide film (for example, a chromia film or an alumina film) naturally formed on the surface of a metal base material) and a metal member (for example, an interconnector 190), A specific area SA exists on the surface of the metal member. Therefore, according to the fuel cell stack 100 of the present embodiment, the unevenness caused by the presence of the plurality of grooves 11 in the specific area SA can be formed into a relatively sharp shape, and the unevenness causes the gas flowing through the gas flow path to be affected by the unevenness. It is possible to effectively hook and trap mixed foreign matter, and as a result, it is possible to effectively suppress the deterioration of the performance of the fuel cell stack 100 and the occurrence of malfunctions of the system including the fuel cell stack 100 due to the foreign matter. can.

Further, in the fuel cell stack 100 of the present embodiment, for at least a part of the specific area SA, the specific direction in the condition (1) regarding the specific area SA is substantially the main flow direction of the gas at the position of the specific area SA. parallel direction. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to prevent the smooth gas flow in the gas flow path from being hindered due to the presence of the plurality of grooves 11 in the specific area SA.

Further, in the fuel cell stack 100 of the present embodiment, for at least a part of the specific area SA, the specific direction in the condition (1) regarding the specific area SA is substantially the main flow direction of the gas at the position of the specific area SA. It is the orthogonal direction. Therefore, according to the fuel cell stack 100 of the present embodiment, the unevenness caused by the presence of the plurality of grooves 11 in the specific area SA can effectively catch and trap foreign matter mixed in the gas flowing through the gas flow path. Therefore, it is possible to effectively suppress the deterioration of the performance of the fuel cell stack 100 and the occurrence of malfunctions of the system including the fuel cell stack 100 due to the foreign matter.

Further, a plurality of specific areas SA exist in the fuel cell stack 100 of the present embodiment, and for one specific area SA, the specific direction in the condition (1) regarding the specific area SA is the position of the specific area SA. , and for other specific areas SA, the specific direction in the above condition (1) regarding the specific area SA is the direction in which the gas flows in the main flow direction at the position of the specific area SA. It is a substantially parallel direction. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to suppress obstruction of smooth gas flow in the gas flow path due to the presence of the plurality of grooves 11 in one specific area SA. Due to the unevenness caused by the presence of the plurality of grooves 11 in the other specific area SA, it is possible to effectively catch and trap the foreign matter mixed in the gas flowing through the gas flow path.

In addition, in the fuel cell stack 100 of the present embodiment, the manifolds include a supply side manifold (oxidant gas supply manifold 161 and fuel gas supply manifold 171) that supplies gas, and a discharge side manifold (oxidant gas discharge manifold) that discharges gas. A manifold 162 and a fuel gas discharge manifold 172) are formed. In addition, each power generation unit 102 has, as a communication flow path, a supply side communication flow path (oxidant gas supply communication hole 132, fuel gas supply communication hole 142, part of air chamber 166, a portion of the fuel chamber 176), and a discharge side communication passage (oxidizing gas discharge communication hole 133, fuel gas discharge communication hole 143, part of the air chamber 166, part of the fuel chamber 176) that communicates the discharge side manifold and the electrode. and are formed. In addition, the surface of the member that defines the gas flow path composed of the supply side manifold and the supply side communication flow path, and the surface of the member that defines the gas flow path composed of the discharge side manifold and the discharge side communication flow path. and , there is a specific area SA. Therefore, according to the fuel cell stack 100 of the present embodiment, on both the gas supply side and the gas discharge side, foreign matter mixed in the gas flowing through the gas flow path is prevented from being caused by the presence of the plurality of grooves 11 in the specific area SA. Therefore, regardless of where the foreign matter is generated, deterioration of the performance of the fuel cell stack 100 and malfunction of the system including the fuel cell stack 100 due to the foreign matter can be effectively suppressed.

In the fuel cell stack 100, the ratio of the area of the specific region SA to the total area of the surface of the member defining the gas flow path composed of the manifold and the communication flow path is preferably 5% or more. % or more is more preferable. When the ratio is 5% or more, foreign matter can be effectively trapped by the unevenness existing in the specific area SA. The occurrence of defects can be effectively suppressed. Further, when the ratio is 10% or more, foreign matter can be trapped extremely effectively by the unevenness existing in the specific area SA, and the performance of the fuel cell stack 100 due to the foreign matter can be lowered or the fuel cell stack 100 can be damaged. It is possible to extremely effectively suppress the occurrence of malfunctions in the system including.

A-5. Performance evaluation:
A performance evaluation was performed on the structure of the gas flow path in the fuel cell stack 100 . FIG. 10 is an explanatory diagram showing performance evaluation results. For the performance evaluation, six fuel cell stack 100 samples (samples S1 to S6) having different surface configurations of members defining gas flow paths were used. Specifically, the single cell separator 120, which is a member that defines a part of the air chamber 166 and a part of the fuel chamber 176 that constitute the supply side and discharge side communication passages on the air electrode side and the fuel electrode side, IC A plurality of grooves 11 (having different sizes of unevenness for each sample) extending substantially parallel to the main gas flow direction were formed on the surfaces of the separator 180 and the interconnector 190 (see FIGS. 5 and 6). A non-contact surface roughness meter was used to measure the maximum height Rz along the direction perpendicular to the main flow direction of the gas on the surface on which the plurality of grooves 11 were formed. It was the value as shown in 10.

For each sample, after 1000 hours of power generation operation at 700 ° C., "adhesion of foreign matter to unevenness", "adhesion of foreign matter to cells", "cracks and cracks in cells", and "decrease in gas flow". We evaluated four items. Regarding the "adherence of foreign matter to irregularities", whether or not foreign matter adheres to the irregularities formed by forming a plurality of grooves 11 on the surface of the member that defines the gas flow path described above is examined using a microscope and an SEM. was confirmed using Regarding "adhesion of foreign matter to the cell", whether or not foreign matter adhered to the surface of each layer constituting the single cell 110 was confirmed using a microscope and SEM. Regarding "cell cracks/fractures", the presence or absence of cracks and cracks in each layer constituting the single cell 110 was confirmed using a microscope and SEM. As for the "decrease in gas flow", the presence or absence of a decrease in gas flow at a place where a plurality of grooves 11 are formed on the surface of the member that defines the gas flow path described above to form an uneven shape was analyzed by a fluid simulation. I confirmed. Based on the evaluation results of the four items, a comprehensive evaluation was made in three stages of A (extremely good), B (good), and C (not good).

In samples S1 to S4, "adherence of foreign matter to irregularities" is "presence", "adhesion of foreign matter to cells" is "absent" (however, sample S1 is "slightly present"), and " "Cracks/fractures in cell" was "absent" (however, sample S1 was "slightly present"). In these samples, since the maximum height Rz is 0.01 μm or more and 50 μm or less, even if the size of the unevenness due to the presence of the plurality of grooves 11 on the surface of the member defining the gas flow path is excessively small, It is considered that the concavities and convexities are not too large and are moderate, so that the concavity and convexity can trap the contaminants, and as a result, the contaminants can be prevented from adhering to the single cell 110 . However, in the sample S1, since the maximum height Rz is less than 0.1 μm, the size of the unevenness caused by the presence of the plurality of grooves 11 on the surface of the member defining the gas flow path is slightly small. It is considered that the foreign matter trapping effect was not obtained as much as the samples S2 to S4. In addition, since the maximum height Rz of the sample S4 is more than 20 μm, the size of the unevenness due to the presence of the plurality of grooves 11 on the surface of the member defining the gas flow path is slightly large. A slight decline was observed. Based on these results, samples S2 and S3 were evaluated as comprehensive evaluation: A (extremely good), and samples S1 and S4 were evaluated as comprehensive evaluation: B (good).

On the other hand, in samples S5 and S6, "adhesion of foreign matter to unevenness" was "absent", "adhesion of foreign matter to cells" was "presence", and "cracks/fractures in cells" were "presence". there were. In the sample S5, since the maximum height Rz is less than 0.01 μm, the size of the unevenness caused by the presence of the plurality of grooves 11 on the surface of the member defining the gas flow path is excessively small, and the unevenness causes the foreign matter to be removed. could not be trapped, and the adhesion of foreign matter to the single cell 110 could not be suppressed. Further, in the sample S6, since the maximum height Rz is more than 50 μm, the size of the unevenness due to the presence of the plurality of grooves 11 on the surface of the member defining the gas flow path is excessively large, and the foreign matter is the unevenness. It is thought that the adhesion of the foreign matter to the single cell 110 could not be suppressed. In addition, in sample S6, since the size of the unevenness due to the presence of the plurality of grooves 11 was excessively large, "decrease in gas flow" was also observed. Based on these results, samples S5 and S6 were evaluated as comprehensive evaluation: C (not good).

According to the above performance evaluation results, a plurality of grooves 11 are formed on the surface of the member defining the gas flow path, and the maximum height Rz along the direction intersecting the extending direction of the grooves 11 is 0.01 μm or more, If the thickness is 50 μm or less, foreign matter mixed in the gas flowing through the gas flow path can be caught and trapped by the unevenness caused by the presence of the plurality of grooves 11, and the performance of the fuel cell stack 100 caused by the foreign matter can be lowered. It can be said that the occurrence of malfunctions in the system including the battery stack 100 can be suppressed. Further, if the maximum height Rz is 0.1 μm or more, the unevenness caused by the presence of the plurality of grooves 11 can effectively hook and trap foreign matter mixed in the gas flowing through the gas flow path. It can be said that this is more preferable because it is possible to effectively suppress the deterioration of the performance of the fuel cell stack 100 and the occurrence of malfunctions of the system including the fuel cell stack 100 due to foreign matter. In addition, if the maximum height Rz is 20 μm or less, it is possible to suppress obstruction of smooth gas flow in the gas flow path due to unevenness caused by the presence of the plurality of grooves 11, which is more preferable. .

B. Variant:
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 scope of the invention. For example, the following modifications are possible.

The configuration of the fuel cell stack 100 and the power generation unit 102 in the above embodiment is merely an example, and various modifications are possible.

In the above embodiment, substantially the entire surface of the member defining the gas flow path is the specific area SA that satisfies the above conditions (1) and (2). At least part of it should be the specific area SA. For example, on only one of the fuel electrode side and the air electrode side, the surface of the member defining the gas flow path may be the specific area SA. Further, the surface of the member defining the gas flow path may be the specific area SA on only one of the supply side and the discharge side. Further, the surface of the member that defines the gas flow path may be the specific area SA in only one of the manifold and the communication flow path. Further, only in some of the power generation units 102 included in the fuel cell stack 100, the surface of the member defining the communication flow path may be the specific area SA.

In the above embodiment, the extending direction of the plurality of grooves 11 in the specific area SA is a direction substantially parallel to the main flow direction of the gas at the position of the specific area SA, or a direction substantially perpendicular to the main flow direction of the gas. However, the extending direction of the plurality of grooves 11 may be other directions.

Although the holes 32 and 34 are formed in the pair of end plates 104 and 106 in the above embodiment, at least one of the pair of end plates 104 and 106 may not be formed with the holes 32 and 34 . In addition, in the above embodiment, the fuel cell stack 100 includes a pair of terminal plates 410, 420, but other members (for example, a pair of end plates 104, 106) are made to function as terminal plates as dedicated members. terminal plates 410 and 420 may be omitted.

In the above-described embodiment, the single-cell separator 120 has the connecting portion 128 that is curved so as to protrude downward from both the inner portion 126 and the outer portion 127 . The shape may be other shapes. Further, the single cell separator 120 may not have the connecting portion 128 . The same applies to the connecting portion 188 in the IC separator 180 .

In the above embodiment, the glass seal portion 125 is arranged near the hole 121 in the single cell separator 120, but the glass seal portion 125 may be omitted.

Although the interconnector 190 includes the conductive coating layer 194 in the above embodiment, the interconnector 190 may not include the coating layer 194 . Further, although the unit cell 110 has the reaction prevention layer 118 in the above embodiment, the unit cell 110 may not have the reaction prevention layer 118 .

In the above embodiment, the single cell 110 is an anode-supported single cell, but may be an electrolyte-supported, metal-supported, or other type of single cell. Further, in the above embodiment, the fuel cell stack 100 is a counterflow type fuel cell, but the fuel cell stack 100 may be another type of fuel cell such as a coflow type.

In the above embodiment, the number of single cells 110 (the number of power generation units 102) included in the fuel cell stack 100 is merely an example, and the number of single cells 110 depends on the output voltage required for the fuel cell stack 100. can be determined as appropriate. In addition, the materials forming each member in the above-described embodiment are merely examples, and each member may be formed of another material. In addition, the technology disclosed in this specification can be similarly applied to at least one fuel cell stack in a form in which the off-gas discharged from the first fuel cell stack is supplied to the second fuel cell stack.

In the above embodiments, SOFCs that generate electricity by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas are used. The present invention can be similarly applied to an electrolytic cell unit, which is a structural unit of a solid oxide electrolysis cell (SOEC) that generates hydrogen using an electrolytic reaction, and an electrolytic cell stack having a plurality of electrolytic cell units. The configurations of the electrolytic cell unit and the electrolytic cell stack are not described in detail here because they are known, for example, as described in JP-A-2016-81813, but generally the power generation unit 102 in the above-described embodiment and the same configuration as the fuel cell stack 100 . That is, the fuel cell stack 100 in the above-described embodiment can be read as an electrolytic cell stack, the power generation unit 102 can be read as an electrolytic cell unit, and the single cell 110 can be read as an electrolytic single cell. However, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the raw material gas is supplied through the manifold. water vapor is supplied as As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and the hydrogen is taken out of the electrolysis cell stack through the manifold. Even in an electrolytic cell stack having such a structure, if a structure similar to that of the above embodiment is adopted, the performance of the electrolytic cell stack may deteriorate due to foreign substances mixed in the gas flowing through the gas flow path, and the system including the electrolytic cell stack may malfunction. can be suppressed.

In the above embodiments, a so-called flat-plate type fuel cell stack was used as an example, but the technology disclosed in this specification is not limited to flat-plate type fuel cell stacks. It can also be applied to a flat plate type or cylindrical type fuel cell stack.

FIG. 11 is an explanatory diagram showing the external configuration of a fuel cell stack 2002 as a modified example. A modified fuel cell stack 2002 shown in FIG. 11 includes a plurality of single cells 2003 . The single cell 2003 has a columnar support extending vertically. The support is flat in cross section and has a pair of opposed flat surfaces. A gas flow path extending in the vertical direction is formed inside the support. A fuel electrode, a solid electrolyte layer, and an air electrode are sequentially stacked on one flat surface of the support, and an interconnector is provided on the other flat surface where the air electrode is not formed. Laminated. By arranging a conductive member 2004 between adjacent unit cells 2003, the unit cells 2003 are electrically connected in series. The single cell 2003 is an example of an electrochemical reaction single cell or an electrochemical reaction unit in the claims.

A lower end of each unit cell 2003 is fixed to a manifold 2007 with a sealing material 2016 such as glass. A gas channel formed in the support of each unit cell 2003 communicates with the internal space of the manifold 2007 . A fuel gas supply pipe 2008 for supplying fuel gas into the manifold 2007 is connected to a side surface of the manifold 2007 . The fuel gas supplied to the manifold 2007 through the fuel gas supply pipe 2008 is supplied from the manifold 2007 to the fuel electrode through the gas flow path formed in the support of each single cell 2003 .

In the fuel cell stack 2002 of the modified example shown in FIG. A portion of the gas flow path formed in the support 2003 from the end of the support on the manifold 2007 side to the fuel electrode is a communication flow path that communicates the manifold and the fuel electrode. In the fuel cell stack 2002 of the modified example shown in FIG. 11 as well, the surface of the member defining the gas flow path composed of the manifold and the communication flow path is provided with a specific material that satisfies the conditions (1) and (2) described above. There is an area SA. Therefore, it is possible to suppress the deterioration of the performance of the fuel cell stack 2002 and the occurrence of malfunctions of the system including the fuel cell stack 2002 due to foreign matter mixed in the gas flowing through the gas flow path.

FIG. 12 is an explanatory diagram showing the external configuration of a fuel cell stack 1100 as another modified example. A fuel cell stack 1100 in this modification comprises a manifold 1002 and a plurality of single cells 1010 . 12, illustration of some unit cells 1010 is omitted.

The manifold 1002 is a member for supplying the fuel gas FG to each unit cell 1010 and recovering the gas discharged from each unit cell 1010, and is a hollow body having a space formed therein. The internal space of manifold 1002 is partitioned into gas supply chamber 1021 and gas recovery chamber 1022 by partition plate 1024 . A gas supply pipe 1201 communicating with a gas supply chamber 1021 is connected to the manifold 1002 , and fuel gas FG is supplied to the gas supply chamber 1021 via the gas supply pipe 1201 . A gas recovery pipe 1202 communicating with a gas recovery chamber 1022 is connected to the manifold 1002 , and the gas in the gas recovery chamber 1022 is discharged to the outside through the gas recovery pipe 1202 . An upper plate portion 1231 constituting the upper surface of the manifold 1002 has a plurality of through holes arranged along the Z-axis direction for communicating the outside (external space) of the manifold 1002 with the gas supply chamber 1021 and the gas recovery chamber 1022 . is formed in

Each unit cell 1010 is a cylindrical member extending in the X-axis direction and having a substantially elliptical YZ cross-sectional shape with the Y-axis direction as the major axis. A base end portion of each unit cell 1010 is inserted into a through hole of the manifold 1002 and joined to the manifold 1002 by a seal portion. As a result, the plurality of unit cells 1010 are arranged side by side along the Z-axis direction. A space between two single cells 1010 adjacent to each other along the Z-axis direction functions as a channel for the oxidant gas. The single cell 1010 is an example of an electrochemical reaction single cell or an electrochemical reaction unit in the claims.

Each unit cell 1010 has a support substrate in which a first gas flow channel and a second gas flow channel extending in the X-axis direction are formed, a fuel electrode, an electrolyte layer, and an air electrode. The base end of the first gas channel communicates with the gas supply chamber 1021 of the manifold 1002 , and the base end of the second gas channel communicates with the gas recovery chamber 1022 of the manifold 1002 . Also, the first gas flow path and the second gas flow path communicate with each other via a communication flow path formed in the communication member 1003 on the distal end side. Each unit cell 1010 is electrically connected to each other in series via a current collecting member.

In the modified fuel cell stack 1100 shown in FIG. 12, the gas flow paths such as the manifold 1002, the gas supply pipe 1201 and the gas recovery pipe 1202 are manifolds for exchange of gas with the fuel electrode of each single cell 1010. , the first gas flow channel and the second gas flow channel formed in the support substrate of each unit cell 1010, and the communication flow channel formed in the communication member 1003 are communication flow channels that connect the manifold and the fuel electrode. be. A specific area SA that satisfies the conditions (1) and (2) described above exists on the surface of the member that defines the gas flow path composed of the manifold and the communication flow path. Therefore, it is possible to suppress the deterioration of the performance of the fuel cell stack 1100 and the occurrence of malfunctions of the system including the fuel cell stack 1100 due to foreign matter mixed in the gas flowing through the gas flow path.

FIG. 13 is an explanatory diagram showing the external configuration of a fuel cell stack 3100 as another modified example. A modified fuel cell stack 3100 shown in FIG. 13 includes a plurality of unit cells 3001 . Each single cell 3001 constitutes a plurality of cell groups 3010 . In the width direction (short side direction) of fuel cell stack 3100, cell group 3010a, cell group 3010b, and cell group 3010a are arranged in this order. are connected at the back of the page. Therefore, the manifold 3002b to which the plurality of unit cells 3001 forming the cell group 3010a are connected and fixed has a "U" shape when viewed from above.

A single cell 3001 is cylindrical and has a fuel electrode, an electrolyte layer, and an air electrode 3008 . Single cell 3001 also has a metal cap 3004 electrically connected to both ends of the anode. Metal cap 3004 is sealed by single cell 3001 and glass material 3005 . A single cell 3001 is erected on a manifold 3002b via an insulating support member 3006 (also referred to as a bush), and is airtightly fixed by a glass ring 3007. As shown in FIG. A portion of the unit cell 3001 is placed below a U-shaped manifold 3002a with an insulating support member 3006 interposed therebetween, and is airtightly joined with a glass ring 3007 . A plurality of unit cells 3001 are electrically connected in series by connecting metal caps 3004 and ends of air electrodes 3008 via current collectors 3009 . The single cell 3001 is an example of an electrochemical reaction single cell or an electrochemical reaction unit in the claims.

The fuel gas reformed by the reformer 3011 is supplied from the fuel gas supply pipe of the manifold 3002a, dispersed inside the manifold 3002a, and the gas of the upstream cell group 3010a connected so as to communicate with the manifold 3002a. It flows through the channel from the other end side to the one end side. The fuel gas discharged from the cell group 3010a and not used for power generation is collected in the manifold 3002b and flows from one end to the other end in the gas flow path of the downstream cell group 3010b with the other end open, It is discharged from the upper end of the cell group 3010b.

In the fuel cell stack 3100 of the modified example shown in FIG. is a communication channel that communicates the manifold and the fuel electrode. In the fuel cell stack 3100 of the modified example shown in FIG. 13 as well, the surface of the member defining the gas flow path composed of the manifold and the communication flow path is provided with a specific material that satisfies the conditions (1) and (2) described above. There is an area SA. Therefore, it is possible to suppress the deterioration of the performance of the fuel cell stack 3100 and the occurrence of malfunctions of the system including the fuel cell stack 3100 due to foreign matter mixed in the gas flowing through the gas flow path.

In the above embodiments, a solid oxide fuel cell (SOFC) was described as an example, but the technology disclosed in this specification includes a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), Other types of fuel cells (or electrolysis cells) such as molten carbonate fuel cells (MCFC) are also applicable.

11: groove 22: bolt 24: nut 26: gas through hole 27: gas passage member 28: main body 29: flange 29A: bolt hole 32, 34: hole 100: fuel cell stack 102: fuel cell power generation unit 103: power generation Block 104: Upper end plate 106: Lower end plate 107: End through hole 108: Communication hole 109: Bolt hole 110: Fuel cell unit cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 118: Reaction prevention layer 120: Single cell separator 121: hole 121: through hole 124: junction 125: glass seal portion 126: inner portion 127: outer portion 128: connecting portion 130: air electrode side frame 131: hole 132: oxidant gas supply communication hole 133 : oxidant gas discharge passage 134: air electrode side collector 140: fuel electrode side frame 141: hole 142: fuel gas supply passage 143: fuel gas discharge passage 144: fuel electrode side collector 145: electrode facing Part 146: Interconnector facing part 147: Connecting part 149: Spacer 150: Flat plate part 161: Oxidant gas supply manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas supply manifold 172: Fuel gas discharge manifold 176: Fuel Chamber 180: IC Separator 181: Through Hole 186: Inner Part 187: Outer Part 188: Connecting Part 189: Lower End Plate 190: Interconnector 194: Coating Layer 196: Conductive Joining Material 200: Insulating Part 210: Terminal Separator 211 : through hole 216: inner portion 217: outer portion 218: connecting portion 220: upper end plate 310: flat portion 320: convex portion 322: outer convex portion 324: inner convex portion 410: upper terminal plate 412: hole 420: lower terminal Plate 510: Flat portion 520: Protruding portion 522: Outer protruding portion 524: Inner protruding portion 600: Reinforcement member 610: Flat plate portion 612: Through hole 620: Cylindrical portion 622: Through hole 1002: Manifold 1003: Communication member 1010: Single cell 1021: Gas supply chamber 1022: Gas recovery chamber 1024: Partition plate 1100: Fuel cell stack 1201: Gas supply pipe 1202: Gas recovery pipe 1231: Upper plate part 2002: Fuel cell stack 2003: Single cell 2004: Conductive member 2007: Manifold 2008: Fuel gas supply pipe 2016: Seal material 3001: Single cell 3002: Manifold 3004: Metal cap 3005: Glass material 3006: Insulating support member 3007: Glass ring 3008: Air electrode 3009: Current collector 3010: Cell group 3011: Reformer 3100: Fuel cell stack SA: Specific area

Claims (8)

An electrochemical reaction cell stack comprising a plurality of electrochemical reaction units each having an electrochemical reaction unit cell including an electrolyte layer and an air electrode and a fuel electrode facing each other with the electrolyte layer interposed therebetween,
For each of the specific electrodes that are at least one of the air electrode and the fuel electrode, a manifold is formed for exchanging gas with the specific electrode of each of the electrochemical reaction units,
Each of the electrochemical reaction units is formed with a communication channel that communicates between the manifold and the specific electrode,
on the surface of a member that defines a gas flow path composed of the manifold and the communication flow path,
(1) A plurality of grooves extending substantially parallel to a specific direction are formed, and
(2) The maximum height Rz along the direction intersecting the specific direction is 0.01 μm or more and 50 μm or less.
There is a specific region that satisfies the condition that
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to claim 1,
The specific region is a region having a maximum height Rz of 0.1 μm or more along a direction intersecting the specific direction.
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to claim 1 or claim 2,
The specific region is a region having a maximum height Rz of 20 μm or less along a direction intersecting the specific direction.
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to any one of claims 1 to 3,
each of the electrochemical reaction units has a metal member including a metal base material and an oxide film formed on the surface of the base material;
The specific region exists on the surface of the metal member,
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to any one of claims 1 to 4,
The specific direction is a direction substantially parallel to the main flow direction of the gas at the position of the specific region,
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to any one of claims 1 to 4,
The specific direction is a direction substantially perpendicular to the main flow direction of the gas at the position of the specific region,
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to any one of claims 1 to 6,
there are a plurality of the specific regions,
The specific direction in one of the specific regions is a direction substantially parallel to the main flow direction of the gas at the position of the specific region, and the specific direction in the other specific region is the position of the specific region. is a direction substantially perpendicular to the main flow direction of the gas of
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to any one of claims 1 to 7,
As the manifold, a supply side manifold for supplying gas and a discharge side manifold for discharging gas are formed,
Each of the electrochemical reaction units includes, as the communication flow path, a supply-side communication flow path that communicates the supply-side manifold and the specific electrode, and a discharge-side communication flow that communicates the discharge-side manifold and the specific electrode. and are formed,
A surface of a member defining the gas flow path composed of the supply side manifold and the supply side communication flow path, and defining the gas flow path composed of the discharge side manifold and the discharge side communication flow path. The specific region exists on both the surface of the member that
An electrochemical reaction cell stack characterized by:

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