JP2018014246A - Electrochemical reaction unit and electrochemical reaction cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the conductivity between a current collector and an interconnector.SOLUTION: An electrochemical reaction unit comprises: an electrochemical reaction single cell including an electrolyte layer, and an air electrode and a fuel electrode which are opposed to each other through the electrolyte layer in a first direction; a metal interconnector disposed on the side of a particular electrode which is at least one of the air electrode and the fuel electrode of the single cell; and a metal current collector disposed between the particular electrode and the interconnector and having a plurality of convex portions put in contact with a surface of the particular electrode. In view from the first direction, the current collector and the interconnector are joined to each other through the diffusion layer even in a second region which is at least a partial region in a non-overlying region which is a region except the overlying region, as well as a first region which is at least a partial region in an overlying region which overlies both of a contact face with the particular electrode in the convex portion of the current collector and a contact face with the interconnector in the current collector.SELECTED DRAWING: Figure 11

Description

  The technology disclosed herein relates to electrochemical reaction units.

  A solid oxide fuel cell (hereinafter referred to as “SOFC”) is known as one type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen. A fuel cell power generation unit (hereinafter simply referred to as “power generation unit”), which is a constituent unit of SOFC, includes a fuel cell single cell (hereinafter simply referred to as “single cell”), an interconnector, and a current collector. The single cell includes an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other in a predetermined direction with the electrolyte layer interposed therebetween. The interconnector is a metal member disposed on the fuel electrode side of the single cell. The current collector is a metal member disposed between the fuel electrode and the interconnector, and has a plurality of protrusions that contact the surface of the fuel electrode. The single cell (the fuel electrode) and the interconnector Ensure electrical conductivity (electrical connection) between the two.

  Conventionally, in a region of a current collector, specifically, a region sandwiched between a fuel electrode and an interconnector and receiving a compressive force (contact pressure) in the predetermined direction, the current collector is obtained by laser welding or resistance welding. A technique is known in which the electrical conductivity between the current collector and the interconnector is secured by joining the connector to the interconnector (see, for example, Patent Document 1).

JP 2014-26974 A

  In the above conventional technique, there is room for improvement with respect to the electrical conductivity between the current collector and the interconnector.

 Such a problem is also a common problem on the air electrode side. That is, there is room for improvement in the electrical conductivity between the interconnector disposed on the air electrode side of the single cell and the current collector disposed between the air electrode and the interconnector. In addition, such a problem is also common to the electrolytic cell unit that is a constituent unit of a solid oxide electrolytic cell (hereinafter referred to as “SOEC”) that generates hydrogen using an electrolysis reaction of water. It is. In the present specification, the fuel cell power generation unit and the electrolysis cell unit are collectively referred to as an electrochemical reaction unit. Such a problem is not limited to SOFC and SOEC, but is common to other types of electrochemical reaction units.

  In this specification, the technique which can solve the subject mentioned above is disclosed.

  The technology disclosed in the present specification can be realized as, for example, the following forms.

(1) An electrochemical reaction unit disclosed in the present specification includes an electrochemical reaction unit cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween; A metal interconnector disposed on the side of the specific electrode that is at least one of the air electrode and the fuel electrode of the chemical reaction unit cell, disposed between the specific electrode and the interconnector, An electrochemical reaction unit comprising: a metal current collector having a plurality of convex portions in contact with the surface; and in contact with the specific electrode in the convex portion of the current collector in the first direction view And a contact surface with the interconnector in the current collector, a first region that is at least a part of the overlapping region that overlaps both, and a small amount in a non-overlapping region that is a region other than the overlapping region In both even and a second region which is a part of a region, and the current collector and said interconnector are bonded through a diffusion layer. According to the present electrochemical reaction unit, the electrical conductivity between the current collector and the interconnector can be improved compared to the configuration in which the current collector and the interconnector are joined only in the overlapping region, The performance of the electrochemical reaction unit can be improved.

(2) In the electrochemical reaction unit, the current collector and the interconnector may not be joined in a third region that is a partial region of the non-overlapping region. According to the present electrochemical reaction unit, in the third region where the current collector and the interconnector are not joined, play is ensured for thermal expansion / contraction in the plane direction (direction orthogonal to the first direction). Therefore, the occurrence of peeling between the current collector and the interconnector due to the difference in thermal expansion can be suppressed.

(3) In the electrochemical reaction unit, the first region and the second region may be separated from each other. According to the present electrochemical reaction unit, the separation between the first region and the second region due to the difference in thermal expansion between the current collector and the interconnector is compared with the configuration in which the first region and the second region are continuous. Generation | occurrence | production can be suppressed effectively.

(4) In the electrochemical reaction unit, the plurality of convex portions are arranged in a lattice shape along a second direction and a third direction orthogonal to the first direction and orthogonal to each other, The second region may be arranged at a position that is not sandwiched between the two first regions in both the second direction and the third direction. According to the present electrochemical reaction unit, the area where the current collector and the interconnector are joined can be arranged in a well-balanced manner in the plane direction (direction orthogonal to the first direction), and the conductivity between the two Can be improved in a balanced manner, and the occurrence of peeling between the two can be effectively suppressed.

(5) In the electrochemical reaction unit, the second region includes two first regions in at least one of a second direction and a third direction orthogonal to the first direction and orthogonal to each other. It is good also as a structure arrange | positioned in the range of 40% of the magnitude | size of the said intermediate area centering on the center point of the said intermediate area among the intermediate areas pinched | interposed. According to the present electrochemical reaction unit, the area where the current collector and the interconnector are joined can be arranged in a well-balanced manner in the plane direction (direction orthogonal to the first direction), and the conductivity between the two Can be improved in a balanced manner, and the occurrence of peeling between the two can be effectively suppressed.

(6) In the electrochemical reaction unit, a portion of the current collector that is located in the overlapping region and a portion that is located in the non-overlapping region may be an integrated member. According to the present electrochemical reaction unit, it is possible to suppress the occurrence of peeling between the current collector and the interconnector in a configuration in which peeling between the current collector and the interconnector is particularly likely to occur.

  Note that the technology disclosed in this specification can be realized in various forms, for example, an electrochemical reaction unit (a fuel cell power generation unit or an electrolysis cell unit), and an electricity provided with a plurality of electrochemical reaction units. It can be realized in the form of a chemical reaction cell stack (fuel cell stack or electrolytic cell stack), a manufacturing method thereof, and the like.

1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present embodiment. It is explanatory drawing which shows the XZ cross-section structure of the fuel cell stack 100 in the position of II-II of FIG. FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of a fuel cell stack 100 at a position of III-III in FIG. It is explanatory drawing which shows XZ cross-section structure of the two electric power generation units 102 adjacent to each other in the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-section structure of the two electric power generation units 102 adjacent to each other in the same position as the cross section shown in FIG. It is explanatory drawing which shows XY cross-section structure of the electric power generation unit 102 in the position of VI-VI of FIG. 4 and FIG. FIG. 6 is an explanatory diagram showing an XY cross-sectional configuration of a power generation unit at a position VII-VII in FIGS. 4 and 5. 3 is an XZ sectional view showing a detailed configuration of a fuel electrode side current collector 144 and an interconnector 150. FIG. 3 is an XZ sectional view showing a detailed configuration of a fuel electrode side current collector 144 and an interconnector 150. FIG. 4 is a YZ sectional view showing a detailed configuration of a fuel electrode side current collector 144 and an interconnector 150. FIG. 4 is an XY cross-sectional view showing a detailed configuration of a fuel electrode side current collector 144 and an interconnector 150. FIG. It is explanatory drawing which shows an evaluation test result. It is YZ sectional drawing which shows the detailed structure of the fuel electrode side collector 144 and the interconnector 150 in 2nd Embodiment. It is XY sectional drawing which shows the detailed structure of the fuel electrode side collector 144 and the interconnector 150 in 2nd Embodiment.

A. Embodiment:
A-1. Device configuration:
(Configuration of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present embodiment, and FIG. 2 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 100 at a position II-II in FIG. FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 at the position of III-III in FIG. In each figure, XYZ axes orthogonal to each other for specifying the direction are shown. In this specification, for the sake of convenience, the positive direction of the Z axis is referred to as the upward direction, and the negative direction of the Z axis is referred to as the downward direction. However, the fuel cell stack 100 is actually different from such an orientation. It may be installed. The same applies to FIG.

  The fuel cell stack 100 includes a plurality (seven in this embodiment) of fuel cell power generation units (hereinafter simply referred to as “power generation units”) 102 and a pair of end plates 104 and 106. The seven power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in the present embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an assembly composed of seven power generation units 102 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the claims.

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

  Bolts 22 extending in the vertical direction are inserted into the communication holes 108, and the fuel cell stack 100 is fastened by the bolts 22 and nuts 24 fitted on both sides of the bolts 22. 2 and 3, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 constituting the upper end of the fuel cell stack 100, and the bolt An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of 22 and the lower surface of the end plate 106 constituting the lower end of the fuel cell stack 100. However, in a place where a gas passage member 27 described later is provided, an insulating sheet disposed between the nut 24 and the surface of the end plate 106 on the upper and lower sides of the gas passage member 27 and the gas passage member 27, respectively. 26 is interposed. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic powder sheet, a glass sheet, a glass ceramic composite agent, or the like.

  The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication hole 108. Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108. As shown in FIGS. 1 and 2, the fuel cell stack 100 is located near the midpoint of one side (the X-axis positive direction side of two sides parallel to the Y-axis) on the outer periphery around the Z-direction. The space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted is introduced with the oxidant gas OG from the outside of the fuel cell stack 100, and the oxidant gas OG is generated by each power generation. It functions as an oxidant gas introduction manifold 161 that is a gas flow path to be supplied to the unit 102, and is the midpoint of the side opposite to the side (X-axis negative direction side of two sides parallel to the Y-axis) The space formed by the bolts 22 (bolts 22B) located in the vicinity and the communication holes 108 through which the bolts 22B are inserted contains the oxidant off-gas OOG that is the gas discharged from the air chamber 166 of each power generation unit 102. Burning Functions as the oxidizing gas discharging manifold 162 for discharging to the outside of the cell stack 100. In the present embodiment, for example, air is used as the oxidant gas OG.

  Further, as shown in FIGS. 1 and 3, the vicinity of the midpoint of one side (the side on the Y axis positive direction side of two sides parallel to the X axis) on the outer periphery of the fuel cell stack 100 around the Z direction The space formed by the bolt 22 (bolt 22D) positioned at the position and the communication hole 108 through which the bolt 22D is inserted is introduced with the fuel gas FG from the outside of the fuel cell stack 100, and the fuel gas FG is generated by each power generation. Bolt 22 that functions as a fuel gas introduction manifold 171 to be supplied to the unit 102 and is located in the vicinity of the midpoint of the opposite side (the side on the Y axis negative direction side of the two sides parallel to the X axis). The space formed by the (bolt 22E) and the communication hole 108 through which the bolt 22E is inserted is a fuel cell stack 1 that uses the fuel off-gas FOG that is a gas discharged from the fuel chamber 176 of each power generation unit 102 as the fuel cell stack 1 Functions as a fuel gas exhaust manifold 172 for discharging to the outside of the 0. In the present embodiment, as the fuel gas FG, for example, hydrogen-rich gas obtained by reforming city gas is used.

  The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow cylindrical main body portion 28 and a hollow cylindrical branch portion 29 branched from the side surface of the main body portion 28. The hole of the branch part 29 communicates with the hole of the main body part 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. Further, as shown in FIG. 2, the hole of the main body portion 28 of the gas passage member 27 disposed at the position of the bolt 22 </ b> A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. The hole of the main body portion 28 of the gas passage member 27 disposed at the position of the bolt 22 </ b> B that forms the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162. Further, as shown in FIG. 3, the hole of the main body portion 28 of the gas passage member 27 arranged at the position of the bolt 22D forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171 and the fuel gas The hole of the main body portion 28 of the gas passage member 27 disposed at the position of the bolt 22 </ b> E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172.

(Configuration of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are formed of, for example, stainless steel. One end plate 104 is disposed on the upper side of the power generation unit 102 located on the uppermost side, and the other end plate 106 is disposed on the lower side of the power generation unit 102 located on the lowermost side. A plurality of power generation units 102 are held in a pressed state by a pair of end plates 104 and 106. The upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100.

(Configuration of power generation unit 102)
4 is an explanatory diagram showing an 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. 5 is adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-section structure of the two electric power generation units. 6 is an explanatory diagram showing an XY cross-sectional configuration of the power generation unit 102 at the position VI-VI in FIGS. 4 and 5, and FIG. 7 is a power generation unit at the position VII-VII in FIGS. 4 and 5. It is explanatory drawing which shows XY cross-section structure of 102. FIG. FIG. 7 shows an enlarged view of a part of the configuration of a fuel electrode side current collector 144 described later.

  As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a separator 120, an air electrode side frame 130, an air electrode side current collector 134, a fuel electrode side frame 140, and a fuel electrode side. A current collector 144 and a pair of interconnectors 150 constituting the uppermost layer and the lowermost layer of the power generation unit 102 are provided. The separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the periphery of the interconnector 150 around the Z direction are formed with holes corresponding to the communication holes 108 through which the bolts 22 are inserted.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member. In this embodiment, the interconnector 150 is formed of a stainless steel material (thermal expansion coefficient at 100 ° C .: 10.1 × 10 ⁻⁶ (1 / K)). The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents reaction gas from being mixed between the power generation units 102. In the present embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by two adjacent power generation units 102. That is, the upper interconnector 150 in a power generation unit 102 is the same member as the lower interconnector 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102. Further, since the fuel cell stack 100 includes the pair of end plates 104 and 106, the power generation unit 102 located at the top in the fuel cell stack 100 does not include the upper interconnector 150 and is located at the bottom. The power generation unit 102 does not include the lower interconnector 150 (see FIGS. 2 and 3).

  The unit cell 110 includes an electrolyte layer 112, and an air electrode (cathode) 114 and a fuel electrode (anode) 116 that face each other in the vertical direction (the arrangement direction in which the power generation units 102 are arranged) with the electrolyte layer 112 interposed therebetween. The single cell 110 of the present embodiment is a fuel electrode-supported single cell that supports the electrolyte layer 112 and the air electrode 114 with the fuel electrode 116.

  The electrolyte layer 112 is a substantially rectangular flat plate member as viewed in the Z direction, and is a dense layer. The electrolyte layer 112 is formed of a solid oxide such as YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), SDC (samarium doped ceria), GDC (gadolinium doped ceria), perovskite oxide, and the like. Yes. The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 when viewed in the Z direction, and is a porous layer. The air electrode 114 is made of, for example, a perovskite oxide (for example, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)). The fuel electrode 116 is a substantially rectangular flat plate member having substantially the same size as the electrolyte layer 112 when viewed in the Z direction, and is a porous layer. The fuel electrode 116 is made of, for example, Ni (nickel), cermet made of Ni and ceramic particles, Ni-based alloy, or the like. Thus, the single cell 110 (power generation unit 102) of the present embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte.

  The separator 120 is a frame-like member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. The peripheral part of the hole 121 in the separator 120 is opposed to the peripheral part of the surface of the electrolyte layer 112 on the air electrode 114 side. The separator 120 is bonded to the electrolyte layer 112 (single cell 110) by a bonding portion 124 formed of a brazing material (for example, Ag brazing) disposed in the facing portion. The separator 120 divides the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116, and gas leaks from one electrode side to the other electrode side in the peripheral portion of the single cell 110. It is suppressed.

 As shown in FIG. 6, the air electrode side frame 130 is a frame-like member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of an insulator such as mica, for example. . The hole 131 of the air electrode side frame 130 forms an air chamber 166 that faces the air electrode 114. The air electrode side frame 130 is in contact with the peripheral edge portion of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge portion of the surface of the interconnector 150 facing the air electrode 114. . The pair of interconnectors 150 included in the power generation unit 102 is electrically insulated by the air electrode side frame 130. The air electrode side frame 130 has an oxidant gas supply communication hole 132 communicating the oxidant gas introduction manifold 161 and the air chamber 166, and an oxidant gas communicating the air chamber 166 and the oxidant gas discharge manifold 162. A discharge communication hole 133 is formed.

  As shown in FIG. 7, the fuel electrode side frame 140 is a frame-like member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. The hole 141 of the fuel electrode side frame 140 forms a fuel chamber 176 that faces the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral portion of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral portion of the surface of the interconnector 150 facing the fuel electrode 116. Further, the fuel electrode side frame 140 has a fuel gas supply communication hole 142 that connects the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that connects the fuel chamber 176 and the fuel gas discharge manifold 172. And are formed.

  As shown in FIG. 6, the air electrode side current collector 134 is disposed in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of current collector elements 135 having a substantially quadrangular prism shape, and is formed of, for example, ferritic stainless steel. The air electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 facing the air electrode 114. However, as described above, since the power generation unit 102 located at the top in the fuel cell stack 100 does not include the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 includes the upper end plate. 104 is in contact. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected. In the present embodiment, the air electrode side current collector 134 and the interconnector 150 are formed as an integral member. That is, a flat plate portion perpendicular to the vertical direction (Z-axis direction) of the integrated member functions as the interconnector 150 and is formed so as to protrude from the flat plate portion toward the air electrode 114. The current collector element 135 that is a plurality of convex portions functions as the air electrode side current collector 134. Moreover, the integral member of the air electrode side current collector 134 and the interconnector 150 may be covered with a conductive coat, and between the air electrode 114 and the air electrode side current collector 134, A conductive bonding layer to be bonded may be interposed.

As shown in FIG. 7, the fuel electrode side current collector 144 is disposed in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, a plurality of electrode facing portions 145, and a plurality of connecting portions 147 that connect the electrode facing portion 145 and the interconnector facing portion 146, and is electrically conductive. It is made of material. The plurality of electrode facing portions 145 are arranged in a lattice shape along the X direction and the Y direction as viewed in the Z direction. In this embodiment, the fuel electrode side current collector 144 is formed of a nickel foil (for example, a thickness of 10 to 200 μm, a coefficient of thermal expansion at 0 to 100 ° C .: 13.3 × 10 ⁻⁶ (1 / K)). Has been. As shown in the partially enlarged view of FIG. 7, the fuel electrode side current collector 144 is manufactured by cutting a substantially rectangular nickel foil and bending the plurality of rectangular portions. Each rectangular part bent up becomes an electrode facing part 145, and a flat plate part in a state where the hole OP other than the bent part is opened becomes an interconnector facing part 146. The electrode facing part 145 and the interconnector facing part 146 are connected to each other. The connecting portion is a connecting portion 147. That is, the fuel electrode side current collector 144 including the interconnector facing portion 146, the electrode facing portion 145, and the connecting portion 147 is an integral member. In addition, in the partial enlarged view in FIG. 7, in order to show the manufacturing method of the fuel electrode side collector 144, the state before a bending raising process is completed about a part of rectangular part is shown. The electrode facing portion 145 is in contact with the surface of the fuel electrode 116 on the side opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 on the side facing the fuel electrode 116. In contact. However, as described above, since the lowermost power generation unit 102 in the fuel cell stack 100 does not include the lower interconnector 150, the interconnector facing portion 146 in the power generation unit 102 has a lower end plate. 106 is in contact. Since the fuel electrode side current collector 144 has such a configuration, the fuel electrode 116 and the interconnector 150 (or the end plate 106) are electrically connected. Note that a spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and the reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 (or the end plate 106) via the fuel electrode side current collector 144. The electrical connection with is maintained well. The fuel electrode side current collector 144 corresponds to a current collector in the claims, and the electrode facing portion 145 corresponds to a convex portion in the claims. One of the X direction and the Y direction corresponds to one of the second direction and the third direction in the claims, and the other of the X direction and the Y direction is the second direction in the claims and It corresponds to the other of the third directions.

A-2. Operation of the fuel cell stack 100:
As shown in FIGS. 2, 4, and 6, the oxidant gas is connected via a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. When OG is supplied, the oxidant gas OG is supplied to the oxidant gas introduction manifold 161 through the branch part 29 of the gas passage member 27 and the hole of the main body part 28, and each power generation unit is supplied from the oxidant gas introduction manifold 161. 102 is supplied to the air chamber 166 through the oxidant gas supply communication hole 132. Further, as shown in FIGS. 3, 5, and 7, the fuel gas is supplied via a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. When the FG is supplied, the fuel gas FG is supplied to the fuel gas introduction manifold 171 through the branch portion 29 of the gas passage member 27 and the hole of the main body portion 28, and the fuel of each power generation unit 102 is supplied from the fuel gas introduction manifold 171. The fuel is supplied to the fuel chamber 176 through the gas supply communication hole 142.

  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, oxygen contained in the oxidant gas OG and hydrogen contained in the fuel gas FG in the single cell 110. Power is generated by an electrochemical reaction. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to one interconnector 150 via the air electrode side current collector 134, and the fuel electrode 116 is connected via the fuel electrode side current collector 144. The other interconnector 150 is electrically connected. The plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, electrical energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as output terminals of the fuel cell stack 100. Since SOFC generates power at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is heated by a heater (after the startup until the high temperature can be maintained by heat generated by power generation) (Not shown).

  The oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 is discharged to the oxidant gas discharge manifold 162 through the oxidant gas discharge communication hole 133 as shown in FIGS. Further, the fuel passes through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162 and is connected to the branch portion 29 through a gas pipe (not shown). It is discharged outside the battery stack 100. Further, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the fuel gas discharge manifold 172 via the fuel gas discharge communication hole 143 as shown in FIGS. 3, 5, and 7. Further, the fuel cell stack 100 is connected to a gas pipe member (not shown) connected to the branch portion 29 through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas discharge manifold 172. Is discharged outside.

A-3. Detailed configuration of fuel electrode side current collector 144 and interconnector 150:
8 and 9 are XZ cross-sectional views showing detailed configurations of the fuel electrode side current collector 144 and the interconnector 150. FIG. 8 is an enlarged view of a portion X1 in FIG. 4, and is a cross-sectional view of the position VIII-VIII in FIG. 11, and FIG. 9 shows the position of IX-IX in FIG. A cross-sectional view is shown. FIG. 10 is a YZ sectional view showing a detailed configuration of the fuel electrode side current collector 144 and the interconnector 150. FIG. 10 is an enlarged view of a portion X2 in FIG. 5 and a cross-sectional view taken along the line XX in FIG. FIG. 11 is an XY cross-sectional view showing a detailed configuration of the fuel electrode side current collector 144 and the interconnector 150. FIG. 11 is a cross-sectional view at the position X3 in FIG. 7 and is a cross-sectional view at positions XI-XI from FIG. 8 to FIG.

  As shown in FIGS. 8 to 11, in the following description, in the fuel electrode side current collector 144 and the interconnector 150, the fuel electrode in each electrode facing portion 145 of the fuel electrode side current collector 144 as viewed in the Z direction. A region that overlaps both the contact surface with 116 and the contact surface with the interconnector 150 in the interconnector facing portion 146 of the fuel electrode side current collector 144 is referred to as an overlapping region ARo. As described above, since the fuel electrode side current collector 144 has a plurality of electrode facing portions (convex portions) 145, a plurality of overlapping regions ARo exist. Each overlapping area ARo is an area where a compression force (contact pressure) in the Z direction acts mainly on the fuel electrode side current collector 144. In the present embodiment, the portion of the interconnector facing portion 146 that overlaps each electrode facing portion 145 when viewed in the Z direction is always in contact with the interconnector 150. Therefore, the overlapping area ARo is opposed to each electrode when viewed in the Z direction. It can be said that the region overlaps the contact surface of the portion 145 with the fuel electrode 116. In this specification, the term “contact” means that the member A and the member B are in contact with each other via another member C in addition to the state in which the member A and the member B are in direct contact with each other. It also includes the state of being. For example, the above-described “contact” between the electrode facing portion 145 and the fuel electrode 116 and “contact” between the interconnector facing portion 146 and the interconnector 150 may be in a state in which both are in direct contact. However, another conductive member (for example, Ni paste) may be interposed between the two. The fuel electrode 116 in the present embodiment corresponds to a specific electrode in the claims.

  In the following description, an area other than each overlapping area ARo is referred to as a non-overlapping area ARn. In the present embodiment, the non-overlapping area ARn is one continuous area (however, an area where each overlapping area ARo is missing) (see FIG. 11).

  In the present embodiment, in at least a part of each overlapping area ARo (hereinafter referred to as “first area AR1”), the fuel electrode side current collector 144 (the interconnector facing portion 146 thereof) and the interconnector 150 are Diffusion bonded. That is, in the first region AR1, the fuel electrode side current collector 144 and the interconnector 150 cause the metal atoms contained in the fuel electrode side current collector 144 and the metal atoms contained in the interconnector 150 to diffuse to each other. The diffusion layer 158 formed by bonding is joined. In the present embodiment, the entire area in each overlapping area ARo is the first area AR1.

  Further, in the present embodiment, in addition to the first area AR1, the fuel electrode side current collector 144 and the interconnector also in a part of the non-overlapping area ARn (hereinafter referred to as “second area AR2”). 150 is diffusion bonded. That is, in the second region AR2, the fuel electrode side current collector 144 and the interconnector 150 cause the metal atoms contained in the fuel electrode side current collector 144 and the metal atoms contained in the interconnector 150 to diffuse to each other. The diffusion layer 158 formed by bonding is joined. In the remaining part of the non-overlapping area ARn (hereinafter referred to as “third area AR3”), the fuel electrode side current collector 144 and the interconnector 150 are not joined.

  As described above, since the plurality of electrode facing portions 145 are arranged in a lattice shape along the X direction and the Y direction as viewed in the Z direction, as shown in FIG. Arranged in a lattice shape along the X and Y directions when viewed in the Z direction. In both the X direction and the Y direction, the third area AR3 is disposed between the two first areas AR1, and the third area AR3 is also defined between the two second areas AR2. Has been placed. Therefore, the second area AR2 is arranged at a position not sandwiched between the two first areas AR1 in both the X direction and the Y direction. The first area AR1 and the second area AR2 are separated from each other.

A-4. Effects of this embodiment:
As described above, in each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment, the contact surface with the fuel electrode 116 in the electrode facing portion 145 of the fuel electrode side current collector 144 as viewed in the Z direction, 1st area | region AR1 which is at least one part area | region in each overlap area | region ARo which overlaps both with the contact surface with the interconnector 150 in the fuel electrode side collector 144, and the non-overlap which is areas other than the overlap area | region ARo The fuel electrode side current collector 144 and the interconnector 150 are joined to each other through the diffusion layer 158 in both the second region AR2 which is a partial region in the region ARn. Therefore, according to the power generation unit 102 of this embodiment, the fuel electrode side current collector 144 and the interconnector 150 are connected to the fuel electrode side current collector 144 and the interconnector 150 only in the overlapping region ARo. The conductivity with the connector 150 can be improved, and the performance of the power generation unit 102 can be improved.

  Further, in the power generation unit 102 of the present embodiment, the fuel electrode side current collector 144 and the interconnector 150 are not joined in the third region AR3 that is a partial region of the non-overlapping region ARn. As described above, in the present embodiment, the fuel electrode-side current collector 144 has a higher coefficient of thermal expansion than the interconnector 150, and therefore the surface direction (the direction perpendicular to the Z direction) due to the difference in thermal expansion between the two. Stress is generated. However, in the power generation unit 102 of the present embodiment, in the third region AR3 in which the fuel electrode side current collector 144 and the interconnector 150 are not joined, it is possible to ensure play for thermal expansion / contraction in the surface direction. Therefore, it is possible to suppress the occurrence of separation between the fuel electrode side current collector 144 and the interconnector 150 due to the difference in thermal expansion.

  Further, in the power generation unit 102 of the present embodiment, the first region AR1 and the second region AR2, which are regions where the fuel electrode side current collector 144 and the interconnector 150 are joined, are separated from each other. Therefore, in the power generation unit 102 of the present embodiment, the heat between the fuel electrode side current collector 144 and the interconnector 150 is compared with a configuration in which the first region AR1 and the second region AR2 are continuous. Generation | occurrence | production of the peeling between both by the expansion difference can be suppressed effectively.

  Further, in the power generation unit 102 of the present embodiment, the fuel electrode side current collector 144 including the interconnector facing portion 146, the electrode facing portion 145, and the connecting portion 147 is an integral member. In other words, the part located in the overlapping area ARo and the part located in the non-overlapping area ARn in the fuel electrode side current collector 144 are an integral member. When the fuel electrode side current collector 144 is configured as such an integral member, separation between the two due to the difference in thermal expansion between the fuel electrode side current collector 144 and the interconnector 150 is particularly likely to occur. However, since the above-described configuration is employed in the power generation unit 102 of the present embodiment, it is possible to suppress the occurrence of peeling between the two.

  Further, in the power generation unit 102 of the present embodiment, the plurality of electrode facing portions 145 of the fuel electrode side current collector 144 are arranged in a lattice shape along the X direction and the Y direction when viewed in the Z direction, The area AR2 is arranged at a position not sandwiched between the two first areas AR1 in both the X direction and the Y direction. Therefore, in the power generation unit 102 of the present embodiment, the region where the fuel electrode side current collector 144 and the interconnector 150 are joined can be disposed in a well-balanced manner in the direction (plane direction) orthogonal to the Z direction. Can be improved in a well-balanced manner, and the occurrence of peeling between the two can be effectively suppressed.

A-5. Method of joining fuel electrode side current collector 144 and interconnector 150:
The joining between the fuel electrode side current collector 144 and the interconnector 150 according to the above embodiment can be realized by, for example, the following method. First, in the second region AR2 in the non-overlapping region ARn, the fuel electrode side current collector 144 and the interconnector 150 can be joined via the diffusion layer 158 by performing resistance welding.

  In the first area AR1 in the overlapping area ARo, a plurality of power generation units 102 are stacked and fastened with bolts 22 to apply contact pressure to the overlapping area ARo. The pole-side current collector 144 and the interconnector 150 can be joined via the diffusion layer 158.

  The above-described joining method is merely an example, and other joining methods (laser welding, ultrasonic welding, etc.) can be used as long as the fuel electrode side current collector 144 and the interconnector 150 can be joined via the diffusion layer 158. ) May be adopted.

A-6. Evaluation test:
In order to verify the effects of the above-described embodiment, a Ni foil that is regarded as the fuel electrode side current collector 144 is placed on the placing surface of a stainless steel plate (10 cm × 10 cm) that is regarded as the interconnector 150. A comparative example (number of samples: 2) of the configuration in which contact pressure is applied to the surface of the Ni foil, and contact pressure is applied to a part of the Ni foil, and the Ni foil and the stainless steel plate are joined to each other by resistance welding. About the Example (the number of samples: 2) of the structure which carried out, the electrical resistance in 700 degreeC was measured. FIG. 12 is an explanatory diagram showing the evaluation test results. As shown in FIG. 12, in the example, the electric resistance tended to be lower than in the comparative example, and the variation in electric resistance was reduced. Also from this result, if the configuration of the power generation unit 102 of the above embodiment is adopted, the conductivity between the fuel electrode side current collector 144 and the interconnector 150 can be improved, and the performance of the power generation unit 102 is improved. It was confirmed that it can be made.

B. Second embodiment:
FIG. 13 is a YZ sectional view showing a detailed configuration of the fuel electrode side current collector 144 and the interconnector 150 in the second embodiment. FIG. 13 is an enlarged view of a portion X2 in FIG. 5, and a cross-sectional view at a position XIII-XIII in FIG. 14 is shown. FIG. 14 is an XY sectional view showing a detailed configuration of the fuel electrode side current collector 144 and the interconnector 150 in the second embodiment. FIG. 14 is a cross-sectional view at a position X3 in FIG. 7, and a cross-sectional view at a position XIV-XIV in FIG.

  As shown in FIGS. 13 and 14, in the second embodiment, the non-overlapping region ARn is a region where the fuel electrode side current collector 144 and the interconnector 150 are joined via the diffusion layer 158. The position of the second area AR2 is different from that of the first embodiment described above. Specifically, in the second embodiment, each second area AR2 is disposed at a position between the two first areas AR1 in the Y direction. In the second embodiment, as in the first embodiment, the first area AR1 and the second area AR2 are separated from each other.

  Further, as shown in FIGS. 13 and 14, in the present embodiment, the second area AR2 is an intermediate area in the intermediate area of the length L1 sandwiched between the two first areas AR1 in the Y direction. It is arranged within a range R1 of 40% of the size of the intermediate area centered on the center point of the area. That is, the second area AR2 is arranged at a position relatively close to the center in the intermediate area of the length L1 sandwiched between the two first areas AR1 in the Y direction. 1 away from the area AR1. Note that, in the Y direction, a region between the second region AR2 sandwiched between the two first regions AR1 and each of the two first regions AR1 is a third region AR3.

  In the power generation unit 102 of the second embodiment, as in the first embodiment described above, the first area AR1 that is at least a part of each overlapping area ARo and the part of the non-overlapping area ARn. In both of the second regions AR2, since the fuel electrode side current collector 144 and the interconnector 150 are joined via the diffusion layer 158, the fuel electrode side current collector 144 and the interconnector 150 are connected to each other. The electrical conductivity of the power generation unit 102 can be improved.

  Further, in the power generation unit 102 of the second embodiment, as in the first embodiment described above, the fuel electrode side current collector 144 and the interconnector 150 in the third region AR3 that is a partial region of the non-overlapping region ARn. Is not joined, it is possible to suppress the occurrence of separation between the fuel electrode side current collector 144 and the interconnector 150. Further, in the power generation unit 102 of the second embodiment, since the first region AR1 and the second region AR2 are separated from each other as in the first embodiment, the fuel electrode side current collector 144 and Generation | occurrence | production of the peeling between both by the thermal expansion difference between the interconnectors 150 can be suppressed effectively. In the power generation unit 102 of the second embodiment, as in the first embodiment described above, the portion located in the overlapping region ARo and the portion located in the non-overlapping region ARn in the fuel electrode side current collector 144 are an integral member. The separation between the two due to the difference in thermal expansion between the fuel electrode side current collector 144 and the interconnector 150 is particularly likely to occur, but the occurrence of the separation between the two is suppressed because of the above configuration. be able to.

  Further, in the power generation unit 102 of the second embodiment, the second area AR2 is an intermediate centered on the center point of the intermediate area among the intermediate areas sandwiched between the two first areas AR1 in the Y direction. Since it is disposed within the range R1 that is 40% of the size of the region, the region where the fuel electrode side current collector 144 and the interconnector 150 are joined in a direction (plane direction) orthogonal to the Z direction is balanced. It can arrange | position, while being able to improve the electrical conductivity between both with sufficient balance, generation | occurrence | production of peeling between both can be suppressed effectively.

C. Variations:
The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are possible.

  The configuration of the fuel cell stack 100 in the above embodiment is merely an example, and various modifications can be made. For example, in the above embodiment, the entire area of each overlapping area ARo is the first area AR1 in which the fuel electrode side current collector 144 and the interconnector 150 are joined via the diffusion layer 158. Only a part of the overlapping area ARo may be the first area AR1.

  Further, in the above embodiment, only a part of the non-overlapping area ARn is the second area AR2 in which the fuel electrode side current collector 144 and the interconnector 150 are joined via the diffusion layer 158, and the rest. Is a third region AR3 in which the fuel electrode side current collector 144 and the interconnector 150 are not joined, but the entire region of the non-overlapping region ARn is the fuel electrode side current collector. 144 may be the second area AR2 where the interconnector 150 is joined.

  In the above embodiment, the first area AR1 and the second area AR2 are separated from each other, but the first area AR1 and the second area AR2 may be continuous. In the second embodiment, the second area AR2 is the size of the intermediate area centered on the center point of the intermediate area among the intermediate areas sandwiched between the two first areas AR1 in the Y direction. However, the arrangement of the second area AR2 is not limited to this, and various modifications can be made.

  Further, the configuration of the fuel electrode side current collector 144 of the above embodiment is merely an example, and various modifications can be made. For example, in the above-described embodiment, the portion located in the overlapping region ARo and the portion located in the non-overlapping region ARn of the fuel electrode side current collector 144 are integrated members, but they may not be integrated members. . Further, the fuel electrode side current collector 144 may be configured to include a plurality of substantially square columnar current collector elements (convex portions), similarly to the air electrode side current collector 134. Also in such a configuration, as in the above embodiment, the contact surface of each convex portion of the fuel electrode side current collector 144 with the fuel electrode 116 and the interconnector in the fuel electrode side current collector 144 are viewed in the Z direction. 150, the first region AR1 that is at least a part of each overlapping region ARo that overlaps both of the contact surfaces with the contact surface 150, and the first part that is a part of the non-overlapping region ARn that is a region other than the overlapping region ARo 2, if the fuel electrode side current collector 144 and the interconnector 150 are joined via the diffusion layer 158, the region between the fuel electrode side current collector 144 and the interconnector 150 is the same. The conductivity can be improved, and the performance of the power generation unit 102 can be improved. In the above embodiment, the fuel electrode side current collector 144 is formed of nickel foil, but the fuel electrode side current collector 144 may be formed of other materials such as Ni mesh. Further, when the fuel electrode side current collector 144 is formed of another material such as Ni mesh, the thickness of the material can be set to 10 to 200 μm, for example. Even if the fuel electrode side current collector 144 has such a configuration, the same effect as in the above embodiment can be obtained.

  Further, instead of the fuel electrode-side current collector 144 or in addition to the fuel electrode-side current collector 144, the air electrode-side current collector 134 also includes the above-described fuel electrode-side current collector 144 and the interconnector 150. The air electrode side current collector 134 and the interconnector 150 may be joined in the same configuration as the joining configuration. In this way, the electrical conductivity between the air electrode side current collector 134 and the interconnector 150 can be improved, and the performance of the power generation unit 102 can be improved.

  Further, in all the power generation units 102 included in the fuel cell stack 100, the above-described joining configuration of the fuel electrode side current collector 144 and the interconnector 150 does not need to be adopted, and the configuration is provided in at least one power generation unit 102. Is adopted, the electrical conductivity between the fuel electrode side current collector 144 and the interconnector 150 can be improved for the power generation unit 102, and the performance of the power generation unit 102 can be improved.

  In the above embodiment, the number of unit cells 110 included in the fuel cell stack 100 is merely an example, and the number of unit cells 110 is appropriately determined according to the output voltage required for the fuel cell stack 100 or the like. Moreover, the material which forms each member in the said embodiment is an illustration to the last, and each member may be formed with another material.

  In the present specification, the fact that the member B and the member C are opposed to each other across the member (or a part having the member, the same applies hereinafter) A is not limited to the form in which the member A and the member B or the member C are adjacent to each other. It includes a form in which another component is interposed between member A and member B or member C. For example, another layer may be provided between the electrolyte layer 112 and the air electrode 114. Even with such a configuration, it can be said that the air electrode 114 and the fuel electrode 116 face each other with the electrolyte layer 112 interposed therebetween.

  Moreover, in the said embodiment, although the fuel cell stack 100 is the structure by which the several flat plate-shaped electric power generation unit 102 was laminated | stacked, this invention is described in other structures, for example, international publication 2012/165409. Thus, the present invention can be similarly applied to a configuration in which a plurality of substantially cylindrical fuel cell single cells are connected in series.

  In the above embodiment, the SOFC that generates electricity using the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas is targeted. The present invention can be similarly applied to an electrolytic cell unit that is a constituent unit of a solid oxide electrolytic cell (SOEC) that generates hydrogen by using hydrogen, and an electrolytic cell stack including a plurality of electrolytic cell units. The configuration of the electrolysis cell stack is well known as described in, for example, Japanese Patent Application Laid-Open No. 2006-81813, and therefore will not be described in detail here, but is roughly the same as the fuel cell stack 100 in the above-described embodiment. It is the composition. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, the power generation unit 102 may be read as an electrolytic cell unit, and the single cell 110 may be read as an electrolytic single cell. However, when the electrolysis cell stack is operated, a voltage is applied between the two electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode). Water vapor as a source gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out of the electrolysis cell stack through the communication hole. Even in the electrolytic cell unit having such a configuration, if the above-described joining configuration between the current collector and the interconnector is employed, the conductivity between the current collector and the interconnector can be improved. Performance can be improved.

 In the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example. However, the present invention is applicable to other types of fuel cells (or electrolytic cells) such as a molten carbonate fuel cell (MCFC). Applicable.

22: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Body portion 29: Branch portion 100: Fuel cell stack 102: Fuel cell power generation unit 104: End plate 106: End plate 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 120: Separator 121: Hole 124: Joint part 130: Air electrode side frame 131: Hole 132: Oxidant gas supply communication hole 133: Oxidant gas discharge communication hole 134: Air Electrode side current collector 135: Current collector element 140: Fuel electrode side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel electrode side current collector 145: Electrode facing portion 146: Inter Connector facing portion 147: Connection portion 149: Spacer 150: Inter Connector 158: diffusion layer 161: oxidizing gas inlet manifold 162: oxidizing gas discharging manifold 166: an air chamber 171: fuel gas inlet manifold 172: fuel gas discharging manifold 176: fuel chamber

Claims (7)

An electrochemical reaction unit cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer;
A metal interconnector disposed on the specific electrode side which is at least one of the air electrode and the fuel electrode of the electrochemical reaction unit cell;
In an electrochemical reaction unit comprising a metal current collector disposed between the specific electrode and the interconnector and having a plurality of convex portions that contact the surface of the specific electrode,
At least a part of the overlapping region that overlaps both the contact surface with the specific electrode in the convex portion of the current collector and the contact surface with the interconnector in the current collector in the first direction view. The current collector and the interconnector are diffused both in the first area that is the first area and the second area that is at least a part of the non-overlapping area other than the overlapping area. Electrochemical reaction unit, characterized in that it is joined via layers. The electrochemical reaction unit according to claim 1,
The electrochemical reaction unit, wherein the current collector and the interconnector are not joined in a third region which is a partial region of the non-overlapping region. In the electrochemical reaction unit according to claim 1 or 2,
The electrochemical reaction unit, wherein the first region and the second region are separated from each other. In the electrochemical reaction unit according to any one of claims 1 to 3,
The plurality of convex portions are arranged in a lattice shape along a second direction and a third direction orthogonal to the first direction and orthogonal to each other,
The second region is disposed in a position not sandwiched between two first regions in both the second direction and the third direction. Reaction unit. In the electrochemical reaction unit according to any one of claims 1 to 3,
The second region is an intermediate region sandwiched between two first regions in at least one of a second direction and a third direction orthogonal to the first direction and orthogonal to each other. The electrochemical reaction unit, which is disposed within a range of 40% of the size of the intermediate region centered on the central point of the intermediate region. In the electrochemical reaction unit according to any one of claims 1 to 5,
The electrochemical reaction unit, wherein the current collector has a part located in the overlapping region and a part located in the non-overlapping region as an integral member. In an electrochemical reaction cell stack comprising a plurality of electrochemical reaction units arranged side by side in the first direction,
The electrochemical reaction cell stack according to claim 1, wherein at least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to claim 1.

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