JP2018200764A - Electrochemical reaction unit and electrochemical reaction cell stack - Google Patents

Abstract

To relax occurrence of bending stress to a single cell due to variation in the protrusion length of first protrusions, while increasing conduction area between a first electrode and a first collector member.SOLUTION: An electrochemical reaction unit comprises a single cell including an electrolyte layer containing a solid oxide and an air electrode and a fuel electrode facing each other while sandwiching the electrolyte layer, a first collector member placed on the side of a first electrode, one of an air electrode and a fuel electrode, for the single cell, and having more than two first protrusions coming into contact with the surface of the first electrode, and a second collector member placed on the side of a second electrode, the other of the air electrode and the fuel electrode, for the single cell, and having multiple second protrusions coming into contact with the surface of the second electrode. The more than two first protrusions include two doubling protrusions doubling the second protrusion when viewing in a first direction, and a non-doubling protrusion placed between the two doubling protrusions, and not doubling the second protrusion when viewing in the first direction.SELECTED DRAWING: Figure 9

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 that is a constituent unit of SOFC includes a single fuel cell. The fuel cell single cell includes an electrolyte layer, and an air electrode and a fuel electrode facing each other in a predetermined direction (hereinafter referred to as “first direction”) with the electrolyte layer interposed therebetween.

  The fuel cell power generation unit includes a conductive air electrode side current collecting member disposed on the air electrode side constituting the fuel cell single cell, and a conductive fuel electrode side current collecting member disposed on the fuel electrode side. (For example, refer to Patent Document 1). The air electrode side current collecting member and the fuel electrode side current collecting member are members for taking out electric power generated by a power generation reaction in the single fuel cell. The air electrode side current collecting member has a plurality of convex portions in contact with the surface of the air electrode. Further, the fuel electrode side current collecting member has a plurality of convex portions that are in contact with the surface of the fuel electrode. During power generation operation, at the portion where the surface of each electrode (air electrode, fuel electrode) and each convex portion of the current collecting member (air electrode side current collecting member, fuel electrode side current collecting member) are in contact, the electrode and current collecting Electrons are exchanged with members. Further, the gas (oxidant gas, fuel gas) supplied to the gas chamber (air chamber, fuel chamber) facing each electrode does not come into contact with each convex portion of the current collecting member among the surfaces of the electrode (each It flows into the electrode from a portion that is not covered by the convex portion.

JP2013-55042A

  In the conventional configuration described above, all of the plurality of convex portions of the fuel electrode side current collecting member (hereinafter referred to as “fuel electrode side convex portion”) as viewed in the vertical direction are convex portions of the air electrode side current collecting member. (Hereinafter, referred to as “air electrode side convex portion”). Here, it is difficult to form the current collecting member so that the protruding lengths toward the electrodes are the same for the plurality of protruding portions of the current collecting member, and the protruding length varies for each protruding portion. There is. In the conventional configuration described above, for example, when the projecting lengths of three adjacent fuel electrode side protrusions vary, each of the three fuel electrode side protrusions is between the air electrode side protrusions and the fuel cell. When the pressing forces applied to the unit cells are different from each other, the unit cell of the fuel cell is subjected to bending stress (for example, three-point bending stress). If the fuel cell unit cell is subjected to bending stress, for example, the fuel cell unit cell may be damaged (cracked or the like), and the performance (power generation performance) of the fuel cell power generation unit may be reduced.

  Note that such a problem is that, in the conventional configuration described above, all of the plurality of air electrode side convex portions of the air electrode side current collecting member have the fuel electrode side of the fuel electrode side current collecting member as viewed in the vertical direction. This is a problem common to fuel cell power generation units arranged so as to overlap the convex portion. It is also a problem common to electrolytic cell units, which are constituent units of solid oxide electrolytic cells (hereinafter referred to as “SOEC”) that generate hydrogen using an electrolysis reaction of water. In the present specification, the fuel cell power generation unit and the electrolysis cell unit are collectively referred to as an electrochemical reaction unit.

  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 a single cell including an electrolyte layer containing a solid oxide and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer; 1st which has three or more 1st convex parts which are arrange | positioned with respect to the said single cell at the 1st electrode side which is one of the said air electrode and the said fuel electrode, and contacts the surface of the said 1st electrode. A current collecting member and a plurality of second protrusions that are disposed on the second electrode side that is the other of the air electrode and the fuel electrode with respect to the single cell, and are in contact with the surface of the second electrode In the electrochemical reaction unit comprising a second current collecting member, the three or more first convex portions are two overlapping convex portions that overlap the second convex portion as viewed in the first direction, Non-overlap that is arranged between the two overlapping convex portions and does not overlap the second convex portion in the first direction view It includes a part, a. According to this electrochemical reaction unit, the three or more first convex portions are arranged between two overlapping convex portions that overlap the second convex portion when viewed in the first direction, and between the two overlapping convex portions. And a non-overlapping convex portion that does not overlap the second convex portion when viewed in the first direction. Thereby, compared with the structure by which all the three or more 1st convex parts are overlapping convex parts, and the overlapping convex parts are arrange | positioned in the relatively near position, the protrusion length of a 1st convex part The generation of bending stress in the single cell due to the variation in thickness can be mitigated. On the other hand, in the configuration in which all of the three or more first convex portions are overlapping convex portions and the overlapping convex portions are disposed at positions relatively distant from each other, it is possible to reduce the occurrence of bending stress to the single cell. However, the conduction area between the first electrode and the first current collecting member is reduced. On the other hand, according to the present electrochemical reaction unit, since there is a non-overlapping convex portion between two overlapping convex portions, the conduction area between the first electrode and the first current collecting member is reduced. Can be suppressed. That is, while increasing the conduction area between the first electrode and the first current collecting member, the generation of bending stress in the single cell due to the variation in the protruding length of the first protrusion is reduced. be able to.

(2) In the electrochemical reaction unit, the three or more first protrusions are arranged at equal intervals in a second direction orthogonal to the first direction, and the plurality of second protrusions Are arranged at equal intervals in the second direction, and the separation distance between the second convex portions may be wider than the arrangement interval between the first convex portions. According to this electrochemical reaction unit, it is suppressed that the overlapping convex portions are arranged close to each other as compared with the configuration in which the separation distance between the second convex portions is narrower than the arrangement interval between the first convex portions. Therefore, it is possible to reduce the occurrence of bending stress in the single cell due to the variation in the protruding length of the overlapping convex portion.

(3) The said electrochemical reaction unit WHEREIN: The said separation distance between said 2nd convex parts is good also as a structure which is 2 times or more of the said arrangement | positioning space | interval of said 1st convex parts. According to this electrochemical reaction unit, the separation distance between the two overlapping protrusions is longer than the configuration in which the separation distance between the second protrusions is smaller than twice the arrangement interval between the first protrusions. Therefore, it is possible to more effectively reduce the bending stress to the single cell due to the variation in the protruding length of the overlapping convex portion.

(4) In the electrochemical reaction unit, the first convex portion and the second convex portion have a rectangular shape in the first direction view, and the first convex portion has the shape of the first convex portion. The minimum side length in the rectangular shape may be shorter than the minimum side length in the rectangular shape of the second convex portion. When the shape of the convex portion (first convex portion, second convex portion) in the first direction view is rectangular, the shorter the minimum side of the rectangular shape of the convex portion is, the shorter the convex portion is. Since stress to the cell is concentrated at a specific location, bending stress to the cell tends to increase. Therefore, according to the present electrochemical reaction unit, the minimum side length of the first convex portion in the rectangular shape is shorter than the minimum side length of the second convex portion in the rectangular shape. That is, the number of the first protrusions having the shortest minimum side length in the rectangular shape overlaps the common second protrusions in the first direction view is one or two. Thereby, the bending stress to the cell by the convex part with the shorter minimum side length in the rectangular shape can be suppressed.

(5) In the electrochemical reaction unit, the minimum side length of the first convex portion in the rectangular shape may be 5 (mm) or less. In the configuration in which the width dimension in the direction orthogonal to the first direction in at least one of the first protrusion and the second protrusion is 5 (mm) or less, the width dimension of the single cell is 5 (mm). A large bending stress is likely to be generated in the single cell due to the stress concentration at the contact portion with the following convex portion. On the other hand, according to the present electrochemical reaction unit, since bending stress to the single cell can be suppressed, such a configuration in which the convex portion having a width dimension of 5 (mm) or less and the single cell are in contact with each other. Is particularly effective.

(6) In the electrochemical reaction unit, the first electrode may be the air electrode, and the second electrode may be the fuel electrode. According to this electrochemical reaction unit, it is possible to suppress a reduction in bending stress to the single cell while increasing a conduction area between the first electrode and the first current collecting member.

  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 an XZ cross-sectional configuration of a fuel cell stack 100 at a position of III-III in FIG. 1. 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 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 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. FIG. 7 is an XY cross-sectional view showing an arrangement relationship between the current collector element 135 and the electrode facing portion 145 in the X1 portion of FIG. 6. It is explanatory drawing which shows the YZ cross-section structure of the electric power generation unit 102 in the position of IX-IX of FIG. 6 and FIG. It is explanatory drawing which shows the XZ cross-section structure of the electric power generation unit 102 in the position of XX of FIG. 6 and FIG. 6 is a YZ cross-sectional view showing an arrangement relationship between a current collector element 135 and an electrode facing portion 145 in a power generation unit 102a of Comparative Example 1. FIG.

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 XZ of the fuel cell stack 100 at a position II-II in FIG. 1 (and FIGS. 6 and 7 described later). FIG. 3 is an explanatory diagram showing a cross-sectional configuration, and FIG. 3 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 100 at the position of III-III in FIG. 1 (and FIGS. 6 and 7 described later). 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. In this specification, a direction perpendicular to the Z-axis direction is referred to as a plane direction.

  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.

  As shown in FIG. 1, each layer (each power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100 penetrates each layer vertically in the periphery of four corners around the Z-axis direction. Holes are formed, and holes corresponding to each other formed in each layer communicate with each other in the vertical direction to constitute a bolt hole 109 extending in the vertical direction from one end plate 104 to the other end plate 106. Bolts 22 are inserted into the respective bolt holes 109, and the fuel cell stack 100 is fastened by the respective bolts 22 and nuts (not shown).

  As shown in FIGS. 1 to 3, a hole penetrating each power generation unit 102 in the vertical direction is formed near the outer periphery of each power generation unit 102 around the Z-axis direction. The holes corresponding to each other are communicated in the vertical direction to form a communication hole 108 extending in the vertical direction across the plurality of power generation units 102. In the following description, a hole formed in each power generation unit 102 to configure the communication hole 108 may also be referred to as the communication hole 108.

  As shown in FIG. 1 and FIG. 2, the fuel cell stack 100 is located in the vicinity of one side (side on the X axis positive direction side of two sides parallel to the Y axis) on the outer periphery around the Z axis direction. The communication hole 108 is supplied with an oxidant gas OG from the outside of the fuel cell stack 100 and is an oxidant gas introduction manifold which is a common gas flow path for supplying the oxidant gas OG to an air chamber 166 described later of each power generation unit 102. The communication hole 108, which functions as 161, and is located in the vicinity of the side opposite to the side (the side on the negative X-axis direction side of the two sides parallel to the Y-axis) is an air chamber 166 of each power generation unit 102. It functions as an oxidant gas discharge manifold 162 that is a common gas flow path for discharging the oxidant off-gas OOG that is the gas discharged from the fuel cell stack 100 to the outside. In the fuel cell stack 100 of the present embodiment, only one oxidant gas introduction manifold 161 and one oxidant gas discharge manifold 162 are present. In the present embodiment, for example, air is used as the oxidant gas OG.

  Further, as shown in FIGS. 1 and 3, in the vicinity of the side that forms the outer periphery of the fuel cell stack 100 around the Z-axis direction, the side closest to the communication hole 108 that functions as the oxidant gas discharge manifold 162 described above. The other communication hole 108 located in is a fuel gas that is a common gas flow path for supplying the fuel gas FG to the fuel chamber 176 described later of each power generation unit 102 after the fuel gas FG is introduced from the outside of the fuel cell stack 100. The other communication hole 108 that functions as the introduction manifold 171 and is located in the vicinity of the side closest to the communication hole 108 that functions as the oxidant gas introduction manifold 161 described above is a gas discharged from the fuel chamber 176 of each power generation unit 102. A fuel gas discharge manifold 17 that is a common gas flow path for discharging the fuel off-gas FOG to the outside of the fuel cell stack 100 To function as. In the fuel cell stack 100 of this embodiment, only one fuel gas introduction manifold 171 and one fuel gas discharge manifold 172 exist. In the present embodiment, for example, hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG.

(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. As shown in FIGS. 2 and 3, four passage through holes 107 are formed in the lower end plate 106. The four flow passage through holes 107 communicate with the oxidant gas introduction manifold 161, the oxidant gas discharge manifold 162, the fuel gas introduction manifold 171, and the fuel gas discharge manifold 172, respectively.

(Configuration of gas passage member 27 and the like)
As shown in FIGS. 2 and 3, the fuel cell stack 100 further includes four gas passages arranged on the opposite side (that is, the lower side) of the plurality of power generation units 102 with respect to the lower end plate 106. A member 27 is provided. The four gas passage members 27 are respectively arranged at positions that overlap the oxidant gas introduction manifold 161, the oxidant gas discharge manifold 162, the fuel gas introduction manifold 171, and the fuel gas discharge manifold 172 in the vertical direction. Each gas passage member 27 has a main body portion 28 in which a hole communicating with the flow passage through hole 107 of the lower end plate 106 is formed, and a cylindrical branch portion 29 branched from the side surface of the main body portion 28. doing. 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. An insulating sheet 26 is disposed between the main body 28 of each gas passage member 27 and the end plate 106. 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.

(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 XZ cross-sectional structure of 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.

  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. In the separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector 150 around the Z-axis direction, the holes constituting the communication holes 108 functioning as the manifolds 161, 162, 171, and 172 described above. Or the hole which comprises each bolt hole 109 is formed.

  The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is formed of, for example, ferritic stainless steel. 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 formed of, for example, a cermet made of Ni and oxide ion conductive ceramic particles (for example, YSZ). 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.

  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 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.

  As shown in FIGS. 4 to 6, the hole 131 of the air electrode side frame 130 is a hole constituting an air chamber 166 facing the air electrode 114. As shown in FIG. 6, the outline of the hole 131 is substantially rectangular as viewed in the Z-axis direction. The hole 131 has a first inner peripheral surface IP1 and a second inner peripheral surface IP2 that face each other in the X-axis direction. Of the outline of the hole 131, a portion constituted by the first inner peripheral surface IP1 and a portion constituted by the second inner peripheral surface IP2 have a linear portion substantially parallel to the Y-axis direction. . As shown in FIGS. 4 and 6, the air electrode side frame 130 communicates with the communication hole 108 constituting the oxidant gas introduction manifold 161 and the first inner periphery of the hole 131 constituting the air chamber 166. The oxidant gas supply communication channel 132 that opens to the surface IP 1 and the communication hole 108 that forms the oxidant gas discharge manifold 162 communicate with the second inner peripheral surface IP 2 of the hole 131 that forms the air chamber 166. An oxidant gas discharge communication channel 133 is formed. In the present embodiment, three oxidant gas supply communication channels 132 and three oxidant gas discharge communication channels 133 are formed in the air electrode side frame 130.

  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 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.

  As shown in FIGS. 4, 5 and 7, the hole 141 of the fuel electrode side frame 140 is a hole constituting a fuel chamber 176 facing the fuel electrode 116. As shown in FIG. 7, the outline of the hole 141 is substantially rectangular when viewed in the Z-axis direction. The hole 141 has a third inner peripheral surface IP3 and a fourth inner peripheral surface IP4 that face each other in the X-axis direction. Of the outline of the hole 141, the portion constituted by the third inner peripheral surface IP3 and the portion constituted by the fourth inner peripheral surface IP4 have a linear portion substantially parallel to the Y-axis direction. . Further, as shown in FIGS. 5 and 7, the fuel electrode side frame 140 communicates with the communication hole 108 constituting the fuel gas introduction manifold 171 and the third inner peripheral surface of the hole 141 constituting the fuel chamber 176. A fuel gas discharge that opens to the fourth inner peripheral surface IP4 of the hole 141 that communicates with the fuel gas supply communication flow path 142 that opens to IP3 and the communication hole 108 that forms the fuel gas discharge manifold 172. A communication channel 143 is formed. In the present embodiment, one fuel gas supply communication channel 142 and one fuel gas discharge communication channel 143 are formed in the fuel electrode side frame 140.

  As shown in FIGS. 4 to 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 FIGS. 4, 5 and 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, an electrode facing portion 145, and a connecting portion 147 that connects the electrode facing portion 145 and the interconnector facing portion 146. For example, nickel or a nickel alloy It is made of stainless steel or the like. 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. In the fuel electrode-side current collector 144, the portion in contact with the fuel electrode 116 is an electrode facing portion 145, and the portion in contact with the interconnector 150 is an interconnector facing portion 146. A portion that is not in contact with any of the interconnector 150 is a connecting portion 147. 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.

A-2. Operation of the fuel cell stack 100:
As shown in FIGS. 2, 4, and 6, the oxidant gas OG 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 oxidant gas introduction manifold 161. When supplied, the oxidant gas OG is supplied to the oxidant gas introduction manifold 161 via the branch portion 29 of the gas passage member 27, the main body portion 28, and the flow-through hole 107 of the lower end plate 106. Then, the gas is supplied from the oxidant gas introduction manifold 161 to the air chamber 166 through the oxidant gas supply communication channel 132 of each power generation unit 102. As shown in FIGS. 3, 5, and 7, the fuel gas FG passes through 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 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, the main body portion 28, and the flow passage through hole 107 of the lower end plate 106, The fuel gas is supplied from the fuel gas introduction manifold 171 to the fuel chamber 176 via the fuel gas supply communication channel 142 of each power generation unit 102.

  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 start-up until the high temperature can be maintained by the heat generated by the 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 via the oxidant gas discharge communication channel 133 as shown in FIGS. Further, the flow passage through hole 107 of the lower end plate 106 and 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 are connected to the branch portion 29. It is discharged outside the fuel cell stack 100 through a gas pipe (not shown). 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 channel 143 as shown in FIGS. A gas pipe connected to the branch portion 29 via the flow passage through hole 107 of the lower end plate 106 and 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. The fuel cell stack 100 is discharged outside (not shown).

  As described above, in each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment, the first inner peripheral surface in which the oxidant gas supply communication channel 132 in the hole 131 of the air electrode side frame 130 opens. The fuel gas supply communication channel 142 in the hole 141 of the fuel electrode side frame 140 is opened in the opposite direction (X-axis direction) between the IP1 and the second inner peripheral surface IP2 in which the oxidant gas discharge communication channel 133 is opened. The facing direction (X-axis direction) between the third inner peripheral surface IP3 and the fourth inner peripheral surface IP4 where the fuel gas discharge communication channel 143 opens is substantially the same direction. Further, the communication hole 108 constituting the oxidant gas introduction manifold 161 and the communication hole 108 constituting the fuel gas discharge manifold 172 are arranged on the same side (X-axis positive direction side) in the facing direction, and the oxidant gas discharge. The communication hole 108 constituting the manifold 162 and the communication hole 108 constituting the fuel gas introduction manifold 171 are disposed on the same side in the facing direction (X-axis negative direction side). Therefore, the main flow direction of the oxidant gas OG in the air chamber 166 of each power generation unit 102 (X-axis negative direction as shown in FIG. 6) and the main flow direction of the fuel gas FG in the fuel chamber 176 (as shown in FIG. 7). And the X axis positive direction) are substantially opposite directions (directions facing each other). That is, the power generation unit 102 (fuel cell stack 100) of this embodiment is a counter flow type SOFC.

A-3. Detailed configuration of air electrode side current collector 134 and fuel electrode side current collector 144:
FIG. 8 is an XY cross-sectional view showing the positional relationship between the current collector element 135 and the electrode facing portion 145 in the X1 portion of FIG. In FIG. 8, the current collector element 135 is indicated by a dotted line so that the arrangement relationship between the current collector element 135 and the electrode facing portion 145 when viewed in the vertical direction (viewed in the Z direction) can be understood. 145 is indicated by a solid line. 9 is an explanatory diagram showing a YZ cross-sectional configuration of the power generation unit 102 at the position IX-IX in FIGS. 6 and 7, and FIG. 10 is a diagram of the power generation unit 102 at the position XX in FIGS. 6 and 7. It is explanatory drawing which shows XZ cross-sectional structure.

  Further, in the following description, the plurality of members B being arranged at equal intervals in the A direction is not limited to the form in which the separation distances between the members B are completely the same, and variations in the separation distances between the members B are ± The form which is 1 (mm) or less is also included. Further, the separation distance between the member (or a part where the member is present, the same applies hereinafter) B and the member C in the A direction is a plane passing through the end of the member B that is closest to the member C and orthogonal to the A direction. The shortest distance between a plane passing through the end of the member C closest to the member B and orthogonal to the A direction. Further, the arrangement interval between the members B in the A direction is a plane that passes through the center of the one member B in the A direction and is orthogonal to the A direction, and another member that is adjacent to the one member B in the A direction. The shortest distance (pitch interval) between a plane passing through the center of B in the A direction and orthogonal to the A direction.

(Configuration of air electrode side current collector 134)
As shown in FIGS. 6 and 8, the shape of each current collector element 135 included in the air electrode side current collector 134 is a substantially rectangular shape when viewed in the vertical direction. Specifically, the shape of the current collector element 135 is substantially rectangular, and the dimensions of the main flow direction (X direction) of the oxidant gas OG and the fuel gas FG described above are directions orthogonal to the flow direction ( Longer than the dimension in the Y direction). Hereinafter, the direction along the long side of the current collector element 135 (X direction) is referred to as the long side direction, and the direction along the short side of the current collector element 135 (Y direction) is referred to as the short side direction. Further, the dimension in the long side direction of the current collector element 135 is referred to as a long side width 135X, and the dimension in the short side direction of the current collector element 135 is referred to as a short side width 135Y. The short side width 135Y is preferably 5 (mm) or less. The long side direction and the short side direction correspond to the second direction in the claims.

  The plurality of current collector elements 135 are arranged so as to be arranged at equal intervals in the short side direction. In FIG. 6, 36 current collector elements 135 are arranged at equal intervals in the short side direction (Y direction). As shown in FIG. 9, in the present embodiment, the second separation distance 135DY in the short side direction between the current collector elements 135 is longer than the short side width 135Y. Further, the second arrangement interval 135PY in the short side direction between the current collector elements 135 is longer than the short side width 135Y.

  The plurality of current collector elements 135 are arranged so as to be arranged at equal intervals in the long side direction. In FIG. 6, six current collector elements 135 are arranged at equal intervals in the long side direction (X direction). As shown in FIG. 10, in the present embodiment, the first separation distance 135DX in the long side direction between the current collector elements 135 is shorter than the long side width 135X. Further, the first arrangement interval 135PX in the longitudinal direction between the current collector elements 135 is substantially the same as the long side width 135X.

(Configuration of fuel electrode side current collector 144)
As shown in FIGS. 7 and 8, the shape of each electrode facing portion 145 included in the fuel electrode side current collector 144 is a substantially rectangular shape when viewed in the vertical direction. Specifically, the electrode facing portion 145 has a substantially rectangular shape, and the dimension of the current collector element 135 in the X direction is longer than the dimension of the current collector element 135 in the Y direction. Therefore, the X direction of the current collector element 135 is the long side direction, and the Y direction of the current collector element 135 is the short side direction. Hereinafter, the dimension in the long side direction of the electrode facing part 145 is referred to as a long side width 145X, and the dimension in the short side direction of the electrode facing part 145 is referred to as a short side width 145Y.

  The plurality of electrode facing portions 145 are arranged so as to be arranged at equal intervals in the short side direction. In FIG. 7, nine electrode facing portions 145 are arranged at equal intervals in the short side direction (Y direction). As shown in FIG. 9, in the present embodiment, the fifth separation distance 145DY in the short side direction between the electrode facing portions 145 is longer than the short side width 145Y of the electrode facing portion 145. Further, the fifth arrangement interval 145PY in the short side direction between the electrode facing portions 145 is longer than the short side width 145Y of the electrode facing portion 145 and is substantially twice the short side width 145Y of the electrode facing portion 145.

  The plurality of electrode facing portions 145 are arranged so as to be aligned in the long side direction. In FIG. 7, twelve electrode facing portions 145 are arranged at equal intervals in the long side direction (X direction). In the present embodiment, a plurality of pairs of electrode facing portions including two electrode facing portions 145 aligned with each other at a third spacing distance 145DX1 in the long side direction are arranged so as to be aligned at a fourth spacing distance 145DX2. As shown in FIG. 10, in this embodiment, the separation distances 145DX1 and 145DX2 in the long side direction between the electrode facing portions 145 are shorter than the long side width 145X of the electrode facing portion 145. The third arrangement interval 145PX1 in the longitudinal direction between the pair of electrode facing portions 145 is substantially the same as the long side width 145X of the electrode facing portion 145, and the fourth arrangement interval 145PX2 between the electrode facing portion pairs is The longer side width 145X of the electrode facing portion 145 is longer.

(Disposition relationship between current collector element 135 and electrode facing portion 145)
(1) Arrangement of current collector element 135 with respect to one electrode facing portion 145 As shown in FIGS. 8 and 9, a plurality of current collector elements 135 have a current collector overlapping the electrode facing portion 145 when viewed in the vertical direction. A body element 135 (hereinafter referred to as “overlapping current collector element 135A”) and a current collector element 135 that does not overlap electrode facing portion 145 (hereinafter referred to as “non-overlapping current collector element 135B”) are included. In the present embodiment, for each of all the electrode facing portions 145, there are two overlapping current collector elements 135A that overlap the electrode facing portions 145 when viewed in the vertical direction. In addition, with respect to all the overlapping current collector elements 135A, the entire short side direction (Y direction) of the overlapping current collector elements 135A overlaps with one electrode facing portion 145 when viewed in the vertical direction. More specifically, when viewed in the vertical direction, both sides in the short side direction of the overlapping current collector element 135A are located on the inner side than both sides in the short side direction of one electrode facing portion 145 (see FIG. 8). In addition, the number of non-overlapping current collector elements 135B that overlaps the space between two electrode facing portions 145 that are adjacent to each other in the short side direction when viewed in the vertical direction is two. That is, the overlapping current collector elements 135A and the non-overlapping current collector elements 135B are arranged alternately in the short side direction by the same number (two).

  Further, the plurality of overlapping current collector elements 135A have the following relationship except for the overlapping current collector elements 135A located at both ends in the short side direction. One overlapping current collector element 135A and one side overlapping disposed on the one side in the short side direction with respect to the one overlapping current collector element 135A at a position closest to the one overlapping current collector element 135A A separation distance from the current collector element 135A is defined as a one-side separation distance. Also, one overlapping current collector element 135A and the other side disposed at a position closest to the one overlapping current collector element 135A on the other side in the short side direction with respect to the one overlapping current collector element 135A The separation distance from the overlapping current collector element 135A is the separation distance on the other side. The one side separation distance and the other side separation distance are different from each other. For example, in FIG. 9, the second overlapping current collector element 135A from the left end of the page is referred to as one overlapping current collector element 135A, and the first overlapping current collector element 135A from the left end of the page is connected to one side (Y The overlapping current collector element 135A on the negative side of the axis), the third overlapping current collector element 135A from the left end of the page (the fifth current collector element 135 from the left side of the page), and the other side (Y axis positive direction) Side) overlapping current collector element 135A. At this time, the one-side separation distance is ΔL1, and the other-side separation distance is ΔL2, which are different. In other words, each of the electrode opposing portions 145 different from each other with respect to the sixth separation distance ΔL1 (same as the second separation distance 135DY) of the two overlapping current collector elements 135A overlapping the common electrode facing portion 145 is provided. The seventh separation distance ΔL2 between the two overlapping current collector elements 135A that overlap is longer (for example, twice or more than the second separation distance 135DY). The seventh separation distance ΔL2 is preferably 1.5 times or more of the sixth separation distance ΔL1, and more preferably twice or more of the sixth separation distance ΔL1.

  Further, the ratio of the total width (M1) in the short side direction of the current collector element 135 in contact with the air electrode 114 to the width (L1) in the short side direction (Y direction) of the air electrode 114 is 30% or more. . The total width (M1) is a total value of widths in the short side direction (in this embodiment, the same as the short side width 135Y) of a region where each of the plurality of current collector elements 135 is in contact with the air electrode 114. It means the total width in the short side direction of the conductive region between the electrode 114 and the air electrode side current collector 134. In addition, when viewed in the vertical direction, the minimum side length (short side width 135Y) of the current collector element 135 in the rectangular shape is the minimum side length (long side width 145X or Shorter side width 145Y).

  In this case, the air electrode 114 corresponds to the first electrode in the claims, the air electrode side current collector 134 corresponds to the first current collector in the claims, and the current collector element 135. Corresponds to the first protrusion in the claims. The fuel electrode 116 corresponds to the second electrode in the claims, the fuel electrode-side current collector 144 corresponds to the second current collector in the claims, and the electrode facing portion 145 includes This corresponds to the second convex portion in the claims. Further, the overlapping current collector element 135A corresponds to the overlapping convex portion in the claims, and the non-overlapping current collector element 135B corresponds to the non-overlapping convex portion in the claims.

(2) Arrangement of electrode facing portion 145 with respect to one current collector element 135 As shown in FIGS. 8 and 10, each of all the electrode facing portions 145 overlaps with the current collector element 135 when viewed in the vertical direction. Yes. In the present embodiment, for each of all current collector elements 135, the number of electrode facing portions 145 that overlap the current collector elements 135 in the vertical direction is two. In addition, with respect to all the electrode facing portions 145, the entire electrode facing portion 145 in the long side direction (X direction) of the current collector element 135 overlaps with one current collector element 135 when viewed in the vertical direction. More specifically, when viewed in the vertical direction, both sides of the electrode facing portion 145 in the long side direction are located on the inner side than both sides in the long side direction of one current collector element 135 (see FIG. 8). In addition, the number of electrode facing portions 145 that overlaps the space between two current collector elements 135 that are adjacent to each other in the long side direction when viewed in the vertical direction is 0 (zero).

  The plurality of electrode facing portions 145 have the following relationship except for the electrode facing portions 145 located at both ends in the long side direction. Separation between one electrode facing portion 145 and one electrode facing portion 145 disposed at a position closest to the one electrode facing portion 145 on one side in the long side direction with respect to the one electrode facing portion 145 Let the distance be one side separation. Also, one electrode facing portion 145, and the other electrode facing portion 145 disposed at a position closest to the one electrode facing portion 145 on the other side in the long side direction with respect to the one electrode facing portion 145, Is the other side separation distance. The one side separation distance and the other side separation distance are different from each other. For example, in FIG. 10, the second electrode facing portion 145 from the left end of the paper surface is defined as one electrode facing portion 145, and the first electrode facing portion 145 from the left end of the paper surface is disposed on one side (X-axis negative direction side). The electrode facing portion 145, and the third electrode facing portion 145 from the left end of the drawing, is the other (X-axis positive direction side) electrode facing portion 145. At this time, the one side separation distance is ΔL3 (third separation distance 145DX1), and the other side separation distance is ΔL4 (fourth separation distance 145DX2), which are different. In other words, with respect to the eighth separation distance ΔL3 between the two electrode facing portions 145 that overlap the common current collector element 135, the second electrode facing portions 145 that respectively overlap the different current collector elements 135 respectively. The separation distance ΔL4 of 9 is longer. The ninth separation distance ΔL4 is preferably 1.5 times or more of the eighth separation distance ΔL3, and more preferably twice or more of the eighth separation distance ΔL3.

  Further, the ratio of the total width (M2) in the long side direction of the electrode facing portion 145 contacting the fuel electrode 116 to the width (L2) of the fuel electrode 116 in the long side direction is 40% or more. The total width (M2) is a combined value of the widths in the long side direction (in this embodiment, the same as the long side width 145X) of the region where each of the plurality of electrode facing portions 145 is in contact with the fuel electrode 116. 116 and the total width in the long side direction of the conductive region between the electrode 116 and the fuel electrode side current collector 144.

  In this case, the fuel electrode 116 corresponds to the first electrode in the claims, the fuel electrode side current collector 144 corresponds to the first current collector in the claims, and the electrode facing portion 145 This corresponds to the first convex portion in the claims. The air electrode 114 corresponds to the second electrode in the claims, the air electrode side current collector 134 corresponds to the second current collector in the claims, and the current collector element 135 is This corresponds to the second convex portion in the claims. The electrode facing portion 145 corresponds to the overlapping convex portion in the claims.

A-4. Effects of this embodiment:
As described above, each power generation unit 102 constituting the fuel cell stack 100 of this embodiment includes the single cell 110, the air electrode side current collector 134, and the fuel electrode side current collector 144. The air electrode side current collector 134 has three or more current collector elements 135 disposed on the air electrode 114 side and in contact with the surface of the air electrode 114. The fuel electrode side current collector 144 has a plurality of electrode facing portions 145 that are disposed on the fuel electrode 116 side and are in contact with the surface of the fuel electrode 116. The three or more current collector elements 135 are disposed between two overlapping current collector elements 135A that overlap the electrode facing portion 145 when viewed in the vertical direction, and between the two overlapping current collector elements 135A. A non-overlapping current collector element 135B that does not overlap the electrode facing portion 145.

  Since each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment has the above-described configuration, as will be described below, between the air electrode 114 (single cell 110) and the air electrode side current collector 134, The generation of bending stress on the single cell 110 due to the variation in the protruding length of the current collector element 135 can be reduced while increasing the conduction area of the current collector element 135. FIG. 11 is a YZ sectional view showing an arrangement relationship between the current collector element 135 and the electrode facing portion 145 in the power generation unit 102a of the first comparative example.

  First, in the configuration of FIG. 9, it is assumed that there are no third and fourth current collector elements 135 (first and second non-overlapping current collector elements 135B from the left end of the page) from the left end of the page. To do. In such a configuration in which the number of current collector elements 135 is small, the conduction area between the single cell 110 and the air electrode side current collector 134 is reduced, and the power generation performance of the fuel cell stack 100 may be reduced. On the other hand, in the configuration of FIG. 9, the first electrode facing portion 145 (fuel electrode side current collector 144) and the second electrode facing portion from the left end of the sheet are not temporarily reduced without decreasing the number of current collector elements 135. 145, an electrode facing portion 145 is newly added, and the added electrode facing portion 145 overlaps the third and fourth current collector elements 135 from the left end of the drawing in the vertical direction. To do. With such a configuration, a decrease in the conduction area between the single cell 110 and the air electrode side current collector 134 is suppressed.

  However, as described below, since three or more overlapping current collector elements 135A are arranged at positions close to each other, the single cell 110 is caused by the variation in the protruding length of the three or more overlapping current collector elements 135A. Bending stress (for example, 3-point bending stress or 4-point bending stress) is likely to occur. First, it is difficult to form the air electrode side current collector 134 such that the protruding lengths toward the air electrode 114 side of the plurality of current collector elements 135 included in the air electrode side current collector 134 are the same. There is a variation in the protruding length for each current collector element 135. As a method for forming the current collector element 135 of the air electrode side current collector 134, various known methods such as cutting and pressing can be adopted, but the current collector is particularly employed when pressing is adopted. Variation in the protruding length of the element 135 is likely to occur.

  For example, the three overlapping current collector elements 135A are in contact with the air electrode 114, and the single cell 110 is sandwiched between the three or more overlapping current collector elements 135A and the electrode facing portion 145. When the protruding length of the overlapping current collector element 135A located at the center of the three overlapping current collector elements 135A is longer than the protruding length of the other two overlapping current collector elements 135A, the single cell 110 is The three-point bending stress with the contact point of the overlapping current collector element 135A located at the center as the movable fulcrum is received. The three-point bending stress increases as the three 135A are arranged closer to each other. When the single cell 110 is subjected to bending stress, for example, the single cell 110 may be damaged (cracked or the like), and the power generation performance of the power generation unit 102a may be reduced. Note that the electrode facing portion 145 does not exist behind the single cell 110 at the contact point of the non-overlapping current collector element 135 </ b> B in the single cell 110. For this reason, the pressing force to the contact location of the overlapping current collector element 135A is larger than the pressing force to the contact location of the non-overlapping current collector element 135B. For this reason, the influence of the bending stress on the single cell 110 due to the variation in the protruding length of the current collector element 135 is particularly large at the contact location of the overlapping current collector element 135A.

  In contrast, according to the present embodiment, the plurality of current collector elements 135 include at least two overlapping current collector elements 135A and a non-currently disposed between the two overlapping current collector elements 135A. And overlapping current collector element 135B. Thereby, it is suppressed that three or more overlapping current collector elements 135A are arranged at positions close to each other. That is, according to the present embodiment, the single cell 110 (air electrode 114) and the air electrode side current collector 134 are compared with the configuration in which the non-overlapping current collector element 135B is not disposed between the overlapping current collector elements 135A. It is possible to suppress the occurrence of bending stress in the single cell 110 while increasing the conduction area between the two.

  Further, according to the present embodiment, the fifth separation distance 145DY of the electrode facing portion 145 is wider than the second arrangement interval 135PY of the current collector elements 135 (see FIG. 9). Here, as in Comparative Example 1 shown in FIG. 11, in the configuration where the sixth separation distance 145 DV between the electrode facing portions 145 is narrower than the second arrangement interval 135 PY of the current collector elements 135, the overlapping current collector elements Since the distance between 135A becomes close, bending stress is likely to occur in the single cell 110 due to variation in the protruding length of the overlapping current collector element 135A. On the other hand, according to the present embodiment, it is possible to alleviate the occurrence of bending stress on the single cell 110 due to the variation in the protruding length of the overlapping current collector element 135A. Furthermore, in the present embodiment, the fifth separation distance 145DY of the electrode facing portion 145 is twice or more the second arrangement interval 135PY of the current collector elements 135 (see FIG. 9). As a result, the distance between the two overlapping current collector elements 135A becomes longer, so that the bending stress to the single cell 110 caused by the variation in the protruding length of the overlapping current collector elements 135A is more effectively reduced. be able to.

  Further, when the shape of the convex portion (the current collector element 135 and the electrode facing portion 145) as viewed in the vertical direction is a rectangular shape, the shorter the minimum side length of the rectangular shape of the convex portion is, the simpler from the convex portion. Since the stress to the cell 110 is concentrated at a specific location, the bending stress to the single cell 110 tends to increase. Therefore, according to this electrochemical reaction unit, the minimum side length (short side width 135Y) in the rectangular shape of the current collector element 135 is equal to the minimum side length (short side width) in the rectangular shape of the electrode facing portion 145. 145Y). The number of the current collector elements 135 having the shortest minimum side length in the rectangular shape overlaps the common electrode facing portion 145 when viewed in the vertical direction is one or two. Thereby, the bending stress to the single cell 110 by the convex part with the shorter minimum side length in the rectangular shape can be suppressed. Moreover, since the short side width 135Y of the current collector element 135 is 5 (mm) or less, stress concentrates on the contact portion of the single cell 110 with the short side of the current collector element 135. A large bending stress is likely to occur in the single cell 110. On the other hand, according to this embodiment, since the bending stress to the single cell 110 can be suppressed, such a configuration in which the convex portion having a width dimension of 5 (mm) or less and the single cell are in contact with each other. It is particularly effective.

B. Variation:
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.

In the embodiment, the air electrode side current collector 134 and the fuel electrode side current collector 144 are exemplified as the current collecting members (first current collecting member, second current collecting member), and the convex portion (first current collecting member) is illustrated. The current collector element 135 and the electrode facing portion 145 are illustrated as the convex portion and the second convex portion. Thus, the current collection member and the convex portion may have, for example, any one of the following configurations.
(1) The current collecting member has a configuration (for example, an air electrode side current collector 134) having a separating portion spaced from the electrode and a columnar protruding portion that protrudes from the separating portion toward the electrode side and contacts the electrode. A convex part is good also as a structure which is this protrusion part (for example, collector element 135).
(2) The current collecting member is configured to follow a change in the separation distance between the electrode (for example, the fuel electrode 116) and the opposing member (for example, the interconnector 150) facing the electrode (for example, the fuel electrode side current collector). 144), and the convex portion may be configured to be a portion (for example, the electrode facing portion 145) in contact with the electrode of the current collecting member. More specifically, the current collecting member is an elastic body that elastically deforms so as to follow a change in the separation distance between the electrode and the opposing member, and the convex portion is a portion of the elastic body that contacts the electrode. It is good also as the structure which is. In this configuration, the convex portion may have a configuration in which the entire portion in contact with the electrode is displaced, or has a cantilever shape in which one end is a fixed end and the other end is a free end. The end side may be configured to be displaceable.

  In the above embodiment, the number of the overlapping current collector elements 135A that overlap the electrode facing portions 145 in the vertical direction is two for each of all the electrode facing portions 145, but this is not limitative. For example, for each of all the electrode facing portions 145, the number of overlapping current collector elements 135A overlapping the electrode facing portion 145 in the vertical direction may be one. In addition, the number of overlapping current collector elements 135A that overlaps the plurality of electrode facing portions 145 when viewed in the vertical direction is one, and the number of overlapping current collector elements 135A that overlap when viewed in the vertical direction is two. The electrode facing portion 145 may be mixed. Furthermore, the plurality of electrode facing portions 145 may include electrode facing portions 145 in which the number of overlapping current collector elements 135A that overlap in the vertical direction is three or more.

  In the above-described embodiment, the number of electrode facing portions 145 that overlap the current collector element 135 is two for each of the current collector elements 135 as viewed in the vertical direction. Absent. For example, the number of electrode facing portions 145 that overlap in the vertical direction view may be one for each of the current collector elements 135. Moreover, the number of the electrode facing portions 145 that overlap the plurality of current collector elements 135 in the vertical direction is one, and the number of the electrode facing portions 145 that overlap in the vertical direction is two. The current collector element 135 may be mixed. Furthermore, the plurality of current collector elements 135 may include current collector elements 135 in which the number of electrode facing portions 145 overlapping in the vertical direction is three or more. In short, at least one of the plurality of second protrusions may be one or two as long as the number of overlapping protrusions is the first protrusion overlapping the second protrusion when viewed in the first direction. .

  In the above embodiment, the number of overlapping current collector elements 135A that overlap one electrode facing portion 145 in the vertical direction is one or two, and also overlaps one current collector element 135 in the vertical direction. Although the number of electrode facing portions 145 is one or two, the present invention is not limited to this. For example, the number of overlapping current collector elements 135A that overlap one electrode facing portion 145 in the vertical direction is one or two. On the other hand, the number of the electrode facing portions 145 that overlap one current collector element 135 in the vertical direction may be three or more, and the overlapping collection that overlaps one electrode facing portion 145 in the vertical direction is also possible. The number of electrical element 135A may be three or more, and the number of electrode facing portions 145 that overlap one current collector element 135 when viewed in the vertical direction may be one or two.

  The configuration of the power generation unit 102 or 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 counter flow type power generation unit 102 is exemplified as the electrochemical reaction unit. However, the present invention is not limited to this, and the cross flow in which the main flow direction of the oxidant gas and the main flow direction of the fuel gas intersect each other. A configuration of a type or a coflow type configuration in which the main flow direction of the oxidant gas and the main flow direction of the fuel gas are the same direction may be used. In the above-described embodiment, the plurality of current collector elements 135 (the plurality of electrode facing portions 145) are arranged so as to be arranged at equal intervals in at least one direction. At least a part of the current collector elements 135 may be arranged so as to be arranged at non-uniform intervals in one direction, and at least a part of the plurality of current collector elements 135 may be arranged in one direction. It may be arranged at a position deviated laterally.

  In the above embodiment, the second separation distance 135DY in the short side direction between the current collector elements 135 may be equal to or shorter than the short side width 135Y of the current collector elements 135. In the above embodiment, the second arrangement interval 135PY in the short side direction between the current collector elements 135 may be equal to or shorter than the short side width 135Y of the current collector elements 135. In the above embodiment, the first separation distance 135DX in the long side direction between the current collector elements 135 may be equal to or longer than the long side width 135X of the current collector elements 135. Further, the first arrangement interval 135PX in the longitudinal direction between the current collector elements 135 may be longer than the long side width 135X of the current collector elements 135, or may be shorter than the long side width 135X of the current collector elements 135. Also good.

  Moreover, in the said embodiment, although the shape of the collector element 135 and the electrode opposing part 145 seen from the up-down direction was a rectangular shape, it is not restricted to this, It is rectangular shapes (for example, square shape) other than a rectangle. It is good also as polygonal shapes other than a rectangle, and circular shape.

  In the above embodiment, the fifth separation distance 145DY in the short side direction between the electrode facing portions 145 may be equal to or shorter than the short side width 145Y of the electrode facing portion 145. In the above embodiment, the fifth arrangement interval 145PY in the short side direction between the electrode facing portions 145 may be equal to or shorter than the short side width 145Y of the electrode facing portion 145.

  In the above-described embodiment, the long-side separation distances 145DX1 and 145DX2 between the electrode facing portions 145 may be greater than or equal to the long side width 145X of the electrode facing portion 145. Further, the third arrangement interval 145PX1 in the longitudinal direction between the pair of electrode facing portions 145 may be wider than the long side width 145X of the electrode facing portion 145, or may be narrower than the long side width 145X of the electrode facing portion 145. Also good. Further, the fourth arrangement interval 145PX2 between the electrode facing portion pairs may be equal to or less than the long side width 145X of the electrode facing portion 145.

  In the above embodiment, a part of the overlapping current collector element 135 </ b> A in the short side direction may protrude beyond both sides of the electrode facing part 145 in the short side direction when viewed in the vertical direction. In addition, a part of the electrode facing portion 145 in the long side direction may protrude outward from both sides of the current collector element 135 in the long side direction when viewed in the vertical direction.

  In the above-described embodiment, for all power generation units 102 included in the fuel cell stack 100, at least one of the plurality of second convex portions overlaps the second convex portion in the first direction view. It is not necessary that the number of the overlapping convex portions is one or two, and for at least one power generation unit 102 included in the fuel cell stack 100, at least one of the plurality of second convex portions is: If the number of overlapping convex portions that are first convex portions that overlap the second convex portion in the first direction view is one or two, the projecting length of the first convex portion for the power generation unit 102 It is possible to alleviate the occurrence of bending stress in the single cell due to the variation of the above.

  In the above embodiment, for the sixth separation distance ΔL1 between the two overlapping current collector elements 135A that overlap the common electrode facing portion 145, two overlapping current collector elements 135A that respectively overlap the different electrode facing portions 145, respectively. The seventh separation distance ΔL2 is longer than each other, but is not limited thereto, and the seventh separation distance ΔL2 may be equal to or less than the sixth separation distance ΔL1. Further, in the above-described embodiment, the two electrode facing portions 145 that respectively overlap the different current collector elements 135 with respect to the eighth separation distance ΔL3 between the two electrode facing portions 145 that overlap the common current collector element 135. The ninth separation distance ΔL4 is longer than each other. However, the present invention is not limited to this, and the ninth separation distance ΔL4 may be equal to or less than the eighth separation distance ΔL3.

  In the above embodiment, the two non-overlapping current collector elements 135B are arranged between the two overlapping current collector elements 135A (see FIG. 9). One or three or more non-overlapping current collector elements 135B may be disposed between 135A. In the above embodiment, all of the plurality of electrode facing portions 145 overlap the current collector element 135 when viewed in the vertical direction, but some of the plurality of electrode facing portions 145 do not overlap the current collector element 135. It is good.

  In the above embodiment, the number of overlapping current collector elements 135A that overlap one electrode facing portion 145 is the same as the number of non-overlapping current collector elements 135B positioned between the two overlapping current collector elements 135A. Although it was (two), it is not restricted to this, The number of the overlapping electrical power collector elements 135A (overlapping convex part) which overlaps with one electrode opposing part 145 (2nd convex part), and two overlapping electrical power collectors There may be more or less than the number of non-overlapping current collector elements 135B (non-overlapping convex portions) positioned between the elements 135A. In the former configuration, a large conduction area between the fuel electrode side current collector 144 and the single cell 110 (fuel electrode 116) is secured by the amount that the electrode facing portions 145 can be arranged at positions close to each other ( The contact density can be increased). With the latter configuration, the distance between the overlapping current collector elements 135A becomes longer, so that the occurrence of bending stress in the single cell 110 due to the variation in the protruding length of the current collector elements 135 can be reduced. Can do. In addition, like the said embodiment, two overlapping convex parts and the non-overlapping convex part arrange | positioned between these two overlapping convex parts are arrange | positioned so that it may be located in a line in one direction continuously. Is preferred.

  In the above embodiment, the bolt holes 109 are provided independently of the manifold communication holes 108. However, the independent bolt holes 109 are not provided, and the manifold communication holes 108 are used as bolt holes. May also be used. In the above embodiment, an intermediate layer may be disposed between the air electrode 114 and the electrolyte layer 112. In the above embodiment, the number of power generation units 102 included in the fuel cell stack 100 is merely an example, and the number of power generation units 102 is appropriately determined according to the output voltage required for the fuel cell stack 100 or the like. Moreover, the material which comprises each member in the said embodiment is an illustration to the last, and each member may be comprised with the other material.

  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 electrolytic cell stack is well known as described in, for example, Japanese Patent Application Laid-Open No. 2006-81813, and thus will not be described in detail here. It is a configuration. 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. Also in the electrolytic cell unit and the electrolytic cell stack having such a configuration, as in the above embodiment, at least one of the plurality of second convex portions overlaps the second convex portion when viewed in the first direction. If the number of overlapping convex portions that are convex portions is one or two, the bending stress to the single cell due to the variation in the protruding length of the first convex portion of the power generation unit 102 Can be mitigated.

22: Bolt 26: Insulating sheet 27: Gas passage member 28: Body portion 29: Branch portion 100: Fuel cell stack 102, 102a: Power generation unit 104, 106: End plate 107: Through hole for flow passage 108: Communication hole 109: Bolt hole 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 120: Separator 121: Hole 124: Joining part 130: Air electrode side frame 131: Hole 132: Oxidant gas supply communication channel 133: Oxidant Gas exhaust communication flow path 134: Air electrode side current collector 135: Current collector element 135A: Overlapping current collector element 135B: Non-overlapping current collector element 135DX: First separation distance 135DY: Second separation distance 135PX: First arrangement interval 135PY: Second arrangement interval 135X: Long side width 135Y: Short side width 14 : Fuel electrode side frame 141: Hole 142: Fuel gas supply communication channel 143: Fuel gas discharge communication channel 144: Fuel electrode side current collector 145: Electrode facing portion 145 DX 1: Third separation distance 145 DX 2: Fourth separation Distance 145DY: Fifth separation distance 145PX1: Third arrangement interval 145PX2: Fourth arrangement interval 145PY: Fifth arrangement interval 145DV: Sixth arrangement interval 145X: Long side width 145Y: Short side width 146: Interconnector Opposing part 147: connecting part 149: spacer 150: interconnector 161: oxidant gas introduction manifold 162: oxidant gas discharge manifold 166: air chamber 171: fuel gas introduction manifold 172: fuel gas discharge manifold 176: fuel chamber FG: fuel Gas FOG: Fuel Off Gas I 1: Inner peripheral surface IP2: Inner peripheral surface IP3: Inner peripheral surface IP4: Inner peripheral surface ΔL1: Sixth separation distance ΔL2: Seventh separation distance ΔL3: Eighth separation distance ΔL4: Nine separation distance OG: Oxidant gas OOG: Oxidant off-gas

Claims (8)

A single cell including an electrolyte layer containing a solid oxide and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer;
1st which has three or more 1st convex parts which are arrange | positioned with respect to the said single cell at the 1st electrode side which is one of the said air electrode and the said fuel electrode, and contacts the surface of the said 1st electrode. A current collecting member;
A second current collector having a plurality of second protrusions arranged on the second electrode side, which is the other of the air electrode and the fuel electrode, with respect to the single cell and in contact with the surface of the second electrode An electrochemical reaction unit comprising a member,
The three or more first convex portions are:
Two overlapping convex portions overlapping the second convex portion in the first direction view;
An electrochemical reaction unit comprising: a non-overlapping convex portion arranged between the two overlapping convex portions and not overlapping the second convex portion in the first direction view. The electrochemical reaction unit according to claim 1,
The three or more first convex portions are arranged at equal intervals in a second direction orthogonal to the first direction,
The plurality of second convex portions are arranged at equal intervals in the second direction,
The electrochemical reaction unit, wherein a separation distance between the second convex portions is wider than an arrangement interval between the first convex portions. The electrochemical reaction unit according to claim 2,
The electrochemical reaction unit, wherein the separation distance between the second protrusions is at least twice the arrangement interval between the first protrusions. In the electrochemical reaction unit according to any one of claims 1 to 3,
In the first direction view,
The shape of the first convex portion and the second convex portion is rectangular, and
An electrochemical reaction unit, wherein a length of a minimum side of the first convex portion in the rectangular shape is shorter than a length of a minimum side of the rectangular shape of the second convex portion. The electrochemical reaction unit according to claim 4,
The electrochemical reaction unit, wherein a length of a minimum side of the first convex portion in the rectangular shape is 5 (mm) or less. In the electrochemical reaction unit according to any one of claims 1 to 5,
The electrochemical reaction unit, wherein the first electrode is the air electrode, and the second electrode is the fuel electrode. In the electrochemical reaction unit according to any one of claims 1 to 6,
An electrochemical reaction unit, wherein the single cell is a fuel cell single cell. 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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