JP6781188B2 - Electrochemical reaction unit and electrochemical reaction cell stack - Google Patents

Description

The techniques disclosed herein relate to electrochemical reaction units.

A solid oxide fuel cell (hereinafter referred to as "SOFC") is known as one of the fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. The fuel cell power generation unit (hereinafter referred to as “power generation unit”), which is a constituent unit of the SOFC, includes a fuel cell single cell (hereinafter referred to as “single cell”). The single cell includes an electrolyte layer and an air electrode and a fuel electrode that face each other in a predetermined direction with the electrolyte layer in between.

In addition, the power generation unit is a metal interconnector that prevents mixing of reaction gas while ensuring an electrical connection with other adjacent power generation units, and is arranged between the interconnector and the fuel electrode to electrify both. It is provided with a metal fuel electrode side current collecting member to be connected. Conventionally, as a fuel electrode side current collecting member, an interconnector facing portion electrically connected to an interconnector, an electrode facing portion electrically connected to the fuel electrode, and an interconnector facing portion and an electrode facing portion are connected. We know the technology to join and fix the interconnector and the interconnector facing part of the fuel electrode side current collecting member by welding (for example, laser welding or resistance welding) using the connecting part and the fuel electrode side current collecting member including the connecting part. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-26843

In the conventional power generation unit configuration, there is room for improvement in terms of electrical connectivity between the fuel electrode and the interconnector, and by extension, there is room for improvement in terms of the electrical performance of the power generation unit.

It should be noted that such a problem is not limited to the relationship between the fuel electrode and the interconnector, but is also a common problem in the relationship between the air electrode and the interconnector. Further, such a problem is not limited to the fuel cell power generation unit, but is a constituent unit of a solid oxide fuel cell (hereinafter referred to as “SOEC”) that generates hydrogen by utilizing the electrolysis reaction of water. This is also a common issue for electrolytic cell units. In this specification, the fuel cell power generation unit and the electrolytic cell unit are collectively referred to as an electrochemical reaction unit. Moreover, such a problem is common not only to the solid oxide fuel cell but also to other types of electrochemical reaction units.

This specification discloses a technique capable of solving the above-mentioned problems.

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

(1) The electrochemical reaction unit disclosed in the present specification includes an electrochemical reaction single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, and the air. A metal interconnector arranged so as to face the first electrode, which is one of the pole and the fuel electrode, and a metal first electrode arranged between the interconnector and the first electrode. A first interconnector facing portion that is electrically connected to the interconnector, a first electrode facing portion that is electrically connected to the first electrode, and the first electrode facing portion. In an electrochemical reaction unit including a first current collecting member including a first connecting portion connecting the interconnector facing portion of the above and the first electrode facing portion, the first current collecting portion is further provided. A metal spacer arranged between the first interconnector facing portion and the first electrode facing portion of the member is provided, and the above is at a position where the interconnector and the first current collecting member are in contact with each other. A first welded portion is formed to join the interconnector, the first interconnector facing portion of the first current collecting member, and the spacer. In the present electrochemical reaction unit, a first welded portion for joining the metal interconnector, the first interconnector facing portion of the first metal current collecting member, and the metal spacer is formed. Therefore, as a conductive path between the first electrode and the interconnector, the first electrode facing portion, the first connecting portion, and the first interconnector facing portion of the first current collecting member from the first electrode are used. In addition to the first conductive path through the interconnector, the first electrode leads to the interconnector through the first electrode facing portion of the first current collector, the spacer, and the first weld. There is also a second conductive path. Thus, according to the present electrochemical reaction unit, the presence of the first weld can increase the conductive path between the first electrode and the interconnector, so that the first electrode and the interconnector The electrical connectivity between the two can be improved, and as a result, the electrical performance of the electrochemical reaction unit can be improved. Further, according to the present electrochemical reaction unit, the presence of the first welded portion can prevent the spacer from being displaced with respect to the first current collecting member, which is caused by the displacement of the spacer. Therefore, it is possible to suppress a decrease in electrical connectivity between the first current collecting member and the first electrode and the interconnector.

(2) In the electrochemical reaction unit, the end portion of the first current collecting member in the first welded portion on the side facing the first electrode is separated from the first electrode facing portion. It may be configured. In this electrochemical reaction unit, since the spacer and the first electrode facing portion of the first current collecting member are not joined by the first welded portion, the spacer and the electrochemical reaction single cell (first electrode) are used. The position of the first electrode facing portion is variable between the two. Therefore, according to the present electrochemical reaction unit, the presence of the first electrode facing portion having a variable position can effectively relieve the stress in the first direction applied to the electrochemical reaction single cell, and electricity can be obtained. Chemical reaction It is possible to effectively suppress the occurrence of damage (cracking, etc.) to a single cell.

(3) In the electrochemical reaction unit, a second metal current collector in contact with the other surface of the surface of the interconnector, which is opposite to one surface with which the first current collector member is in contact. A member may be provided, and the first welded portion may be formed so as to join the second current collecting member, the interconnector, and the first current collecting member. In this electrochemical reaction unit, the presence of the first welded portion can increase the conductive path between the second electrode and the interconnector in addition to the distance between the first electrode and the interconnector. The electrical connectivity between the second electrode and the interconnector can be improved in addition to between the first electrode and the interconnector, resulting in further improvement in the electrical performance of the electrochemical reaction unit. Can be made to. Further, in the present electrochemical reaction unit, for example, the above effect can be obtained by the presence of one welded portion as compared with a configuration in which a welded portion for joining the second current collecting member and the interconnector is separately formed. This makes it possible to simplify the equipment configuration and improve the efficiency of the manufacturing process.

(4) In the electrochemical reaction unit, the second current collecting member includes a plate-shaped second interconnector facing portion electrically connected to the interconnector and the other electrochemical reaction unit. A plate-shaped second electrode facing portion electrically connected to a second electrode which is the other of the air electrode and the fuel electrode of the electrochemical reaction single cell, and the second interconnector facing portion. The first welded portion includes a second connecting portion connecting the second electrode facing portion, the first welded portion includes the second interconnector facing portion of the second current collecting member, the interconnector, and the above. The configuration may be formed so as to join the first current collecting member. According to the present electrochemical reaction unit, it is possible to prevent the first welded portion from projecting to the other electrochemical reaction single cell side facing the interconnector with the second current collecting member interposed therebetween. It is possible to prevent the electrochemical reaction single cell from interfering with the first welded portion and causing damage (cracking or the like) to the electrochemical reaction single cell.

(5) In the electrochemical reaction unit, a second metal current collector in contact with the other surface of the surface of the interconnector, which is opposite to one surface with which the first current collector member is in contact. A second welded portion for joining the interconnector and the second current collecting member is formed at a position where the member is provided and the interconnector and the second current collecting member are in contact with each other. The diameter at the position of one surface of the interconnector in the welded portion is larger than the diameter at the position of the other surface of the interconnector, and the diameter of the one surface of the interconnector at the second welded portion The diameter at the position of may be smaller than the diameter at the position of the other surface of the interconnector. In this electrochemical reaction unit, as a conductive path between the second electrode and the interconnector, the second electrode facing portion of the second current collecting member, the second electrode facing portion, the second connecting portion, and the second There is a conductive path through the interconnect facing portion and the second weld to the interconnector. Therefore, according to the present electrochemical reaction unit, the conductive path between the second electrode and the interconnector can be increased, and the electrical connectivity between the second electrode and the interconnector can be improved. As a result, the electrical performance of the electrochemical reaction unit can be further improved. Further, in the present electrochemical reaction unit, since the relationship between the diameters of the first welded portion and the second welded portion at the positions of the respective surfaces of the interconnectors is as described above, the first welded portion and the second welded portion are used. The welding directions when forming the welded portions are opposite to each other, and it is possible to suppress the occurrence of warpage of the interconnector due to the provision of the first welded portion and the second welded portion.

(6) In the electrochemical reaction unit, the electrochemical reaction single cell may be configured to be a fuel cell single cell. According to the present electrochemical reaction unit, the electrical connectivity between the first electrode and the interconnector can be improved, and as a result, the power generation performance of the electrochemical reaction unit can be improved.

The technique disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction unit (fuel cell power generation unit or electrolytic cell unit), and electricity having 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 method for producing them, and the like.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of II-II of FIG. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of III-III of FIG. It is explanatory drawing which shows the XZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-sectional structure of two power generation units 102 adjacent to each other at the position of VI-VI of FIG. 7 and FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VII-VII of FIGS. 4 to 6. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VIII-VIII of FIGS. 4 to 6. It is explanatory drawing which shows schematic structure of the power generation unit 102a in 2nd Embodiment.

A. First Embodiment:
A-1. Device configuration:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 according to the present embodiment, and FIG. 2 is a perspective view of the fuel cell stack 100 at the position II-II of FIG. 1 (and FIGS. 7 and 8 described later). It is explanatory drawing which shows the XZ cross-sectional structure, and FIG. 3 is the explanatory view which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position III-III of FIG. 1 (and FIG. 7 and FIG. 8 which will be described later). Each figure shows XYZ axes that are orthogonal to each other to identify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction, but the fuel cell stack 100 is actually in a direction different from such an orientation. It may be installed. The same applies to FIGS. 4 and later. Further, in the present specification, the direction orthogonal to the Z-axis direction is referred to as a plane direction.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cell power generation units (hereinafter, simply referred to as “power generation units”) 102, 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 aggregate 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 is vertically penetrated around the four corners of the outer periphery of each layer (each power generation unit 102, end plate 104, 106) constituting the fuel cell stack 100 in the Z-axis direction. The holes are formed, and the holes formed in each layer and corresponding to each other communicate with each other in the vertical direction to form a bolt hole 109 extending in the vertical direction from one end plate 104 to the other end plate 106. A bolt 22 is inserted into each bolt hole 109, and the fuel cell stack 100 is fastened by each bolt 22 and a nut (not shown).

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

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

Further, as shown in FIGS. 1 and 3, among the sides constituting the outer periphery of the fuel cell stack 100 in the Z-axis direction, the vicinity of the side closest to the communication hole 108 functioning as the above-mentioned oxidant gas discharge manifold 162. The other communication hole 108 located in is a gas flow path in which the fuel gas FG is introduced from the outside of the fuel cell stack 100 and the fuel gas FG is supplied to the fuel chamber 176 described later in each power generation unit 102. The other communication holes 108 located near the side closest to the communication holes 108 that function as the manifold 171 and function as the oxidant gas introduction manifold 161 described above are the gases discharged from the fuel cell 176 of each power generation unit 102. It functions as a fuel gas discharge manifold 172, which is a gas flow path for discharging a certain fuel off-gas FOG to the outside of the fuel cell stack 100. As the fuel gas FG, for example, a hydrogen-rich gas obtained by reforming city gas is used.

(Structure of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is arranged above the power generation unit 102 located at the top, and the other end plate 106 is arranged below the power generation unit 102 located at the bottom. 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, the lower end plate 106 is formed with four flow path through holes 107. The four flow path 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.

(Structure of gas passage member 27, etc.)
As shown in FIGS. 2 and 3, the fuel cell stack 100 further has 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 arranged at positions overlapping 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. Each gas passage member 27 has a main body portion 28 in which a hole communicating with the flow path through hole 107 of the lower end plate 106 is formed, and a tubular branch portion 29 branched from the side surface of the main body portion 28. doing. The hole of the branch portion 29 communicates with the hole of the main body portion 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. An insulating sheet 26 is arranged 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 dust sheet, a glass sheet, a glass-ceramic composite agent, or the like.

(Structure of power generation unit 102)
FIG. 4 is an explanatory view 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 an explanatory view showing an XZ cross-sectional configuration at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XZ cross-sectional structure of two power generation units 102, and FIG. 6 is the explanatory view which shows the YZ cross-sectional structure of two power generation units 102 which are adjacent to each other at the position of VI-VI of FIG. 7 and FIG. Is. Further, FIG. 7 is an explanatory view showing an XY cross-sectional configuration of the power generation unit 102 at the position of VII-VII of FIGS. 4 to 6, and FIG. 8 is a power generation unit at the position of VIII-VIII of FIGS. 4 to 6. It is explanatory drawing which shows the XY cross-sectional structure of 102.

As shown in FIGS. 4 to 6, the power generation unit 102 includes a single cell 110, a separator 120, an air pole side frame 130, an air pole side current collector 134, a fuel pole side frame 140, and a fuel pole side. It includes a current collector member 144 and a pair of interconnectors 150 that form the uppermost layer and the lowermost layer of the power generation unit 102. Holes forming communication holes 108 functioning as the above-mentioned manifolds 161, 162, 171 and 172 are formed on the peripheral edges of the separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector 150 in the Z-axis direction. Or, holes forming each bolt hole 109 are formed.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is formed of, for example, a metal such as ferritic stainless steel, which is a metal containing Cr (chromium). The interconnector 150 is a member for ensuring an electrical connection between the power generation units 102 and preventing mixing of the reaction gas between the power generation units 102. In the present embodiment, the surface of the interconnector 150 on the side facing the air electrode 114, which will be described later, is covered with the conductive coat 151. Coating 151, for _example, it is formed by Mn 2 CoO ₄ and _{MnCo 2 O 4, ZnCo 2 O} 4, ZnMnCoO 4, spinel oxides such CuMn ₂ O _4. The formation of the coat 151 on the surface of the interconnector 150 is performed by well-known methods such as spray coating, inkjet printing, spin coating, dip coating, plating, sputtering, and thermal spraying. The presence of the coat 151 suppresses the emission and diffusion of Cr from the interconnector 150 to the air electrode 114 side, and Cr adheres to the surface of the air electrode 114 to reduce the electrode reaction rate at the air electrode 114. The occurrence of a phenomenon called "114 Cr poisoning" is suppressed. In the following description, unless otherwise specified, "interconnector 150" means "interconnector 150 covered with coat 151". Further, 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 certain 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 a pair of end plates 104 and 106, the power generation unit 102 located at the top of the fuel cell stack 100 does not have 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 single cell 110 includes an electrolyte layer 112, an air electrode (cathode) 114 and a fuel electrode (anode) 116 facing each other in the vertical direction (arrangement direction in which the power generation units 102 are arranged) with the electrolyte layer 112 in between. The single cell 110 of the present embodiment is a fuel pole support type single cell in which the fuel pole 116 supports the electrolyte layer 112 and the air pole 114.

The electrolyte layer 112 is a flat plate-shaped member that is substantially rectangular in the Z-axis direction, and is a dense layer. The electrolyte layer 112 is formed of, for example, a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxide. There is. The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 in the Z-axis direction, and is a porous layer. The air electrode 114 is formed of, for example, a perovskite-type oxide (for example, LSCF (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)). The air electrode 114 in this embodiment corresponds to the second electrode in the claims. The fuel electrode 116 is a substantially rectangular flat plate-shaped member having substantially the same size as the electrolyte layer 112 in the Z-axis direction, and is a porous layer. The fuel electrode 116 is formed of, for example, a cermet composed of Ni and oxide ion conductive ceramic particles (for example, YSZ). The fuel electrode 116 in this embodiment corresponds to the first electrode in the claims. As described above, 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-shaped member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is made of, for example, a metal such as stainless steel. The peripheral portion of the hole 121 in the separator 120 faces the peripheral edge of the surface of the electrolyte layer 112 on the side of the air electrode 114. 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 wax) arranged at the opposite portion thereof. The separator 120 partitions the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116, and a gas leak from one electrode side to the other electrode side at the peripheral edge of the single cell 110. It is suppressed. A seal member (for example, a glass seal member) that seals between the air chamber 166 and the fuel chamber 176 may be further provided near the joint between the single cell 110 and the separator 120.

As shown in FIGS. 4 to 7, the air electrode side frame 130 is a frame-shaped member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of, for example, an insulator such as mica. Has been done. The air electrode side frame 130 is in contact with the peripheral edge of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the air electrode 114. .. The holes 131 formed in the air electrode side frame 130 form an air chamber 166 facing the air electrode 114. Further, the air electrode side frame 130 electrically insulates between the pair of interconnectors 150 included in the power generation unit 102. Further, in the air electrode side frame 130, the oxidant gas supply communication flow path 132 that communicates the oxidant gas introduction manifold 161 and the air chamber 166, and the oxidant that communicates the air chamber 166 and the oxidant gas discharge manifold 162. A gas discharge communication flow path 133 is formed.

As shown in FIGS. 4 to 6 and 8, the fuel electrode side frame 140 is a frame-shaped member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is, for example, a metal such as stainless steel. Is formed by. The fuel electrode side frame 140 is in contact with the peripheral edge of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the fuel electrode 116. The holes 141 formed in the fuel pole side frame 140 form a fuel chamber 176 facing the fuel pole 116. Further, in the fuel electrode side frame 140, a fuel gas supply communication flow path 142 that communicates the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication flow that communicates the fuel chamber 176 and the fuel gas discharge manifold 172. A road 143 is formed.

As shown in FIGS. 4 to 6 and 8, the fuel electrode side current collecting member 144 is a conductive member arranged between the interconnector 150 and the fuel electrode 116 of the single cell 110, and is, for example, nickel or It is made of metal such as nickel alloy foil or mesh. The fuel pole side current collector 144 is in contact with the surface of the fuel pole 116 on the side opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 on the side facing the fuel pole 116. However, as described above, since the power generation unit 102 located at the bottom of the fuel cell stack 100 does not have the lower interconnector 150, the fuel electrode side current collecting member 144 in the power generation unit 102 is on the lower side. It is in contact with the end plate 106. Since the fuel pole side current collecting member 144 has such a configuration, the fuel pole 116 and the interconnector 150 (or the end plate 106) are electrically connected. The configuration of the fuel electrode side current collector 144 will be described in more detail later. The fuel electrode side current collecting member 144 in the present embodiment corresponds to the first current collecting member within the scope of the claims.

The fuel pole side current collector 144 and the fuel pole 116 may be joined by a conductive bonding layer. In that case, when the fuel pole side current collector 144 comes into contact with the surface of the fuel pole 116. Includes a state in which the fuel electrode side current collector 144 and the fuel electrode 116 are in contact with each other via a bonding layer.

As shown in FIGS. 4 to 7, the air electrode side current collecting member 134 is a conductive member arranged between the interconnector 150 and the air electrode 114 of the single cell 110, and is, for example, a ferrite stainless steel or the like. It is made of metal. The air electrode side current collecting member 134 has a surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and a surface of the interconnector 150 on the side facing the air electrode 114 (in other words, of the interconnector 150). Of the surfaces, the fuel electrode side current collector 144 is in contact with one surface (upper surface in this embodiment) and the other surface (lower surface) on the opposite side. However, as described above, since the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150, the air electrode side current collecting member 134 in the power generation unit 102 is the upper end plate. It is in contact with 104. Since the air electrode side current collecting member 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected. The configuration of the air electrode side current collecting member 134 will be described in more detail later. The air electrode side current collecting member 134 in the present embodiment corresponds to the second current collecting member within the scope of the claims.

In the present embodiment, the air electrode side current collecting member 134 is covered with a conductive coat 38 similar to the coat 151 covering the above-mentioned interconnector 150. As a result, the release / diffusion of Cr from the current collecting member 134 on the air electrode side is suppressed, and the generation of Cr poisoning of the air electrode 114 is suppressed. In the following description, unless otherwise specified, the "air pole side current collecting member 134" means the "air pole side current collecting member 134 covered with the coat 38". Further, in the present embodiment, the air electrode side current collecting member 134 and the air electrode 114 are joined by a conductive joining layer 138. The bonding layer 138 is formed of, for example, spinel-type oxides such as Mn ₂ CoO ₄ , Mn Co ₂ O ₄ , ZnCo ₂ O ₄ , ZnMn CoO ₄ , and CuMn ₂ O ₄ . The bonding layer 138 is formed, for example, by printing the bonding layer paste on the current collecting member 134 on the air electrode side and firing the bonding layer paste under predetermined conditions while pressing the bonding layer paste against the surface of the air electrode 114. can do. In the present specification, when the air electrode side current collecting member 134 is in contact with the surface of the air electrode 114, the two are in contact with each other via a bonding layer 138 that joins the air electrode side current collecting member 134 and the air electrode 114. including.

As described above, in the present embodiment, one interconnector 150 is shared by two adjacent power generation units 102. Therefore, when focusing on one interconnector 150, one side of the interconnector 150 (for example, The fuel pole side current collecting member 144 located on the surface of the upper side) is electrically connected to the fuel pole 116 of the single cell 110 constituting one power generation unit 102, and is electrically connected to the other side (for example, the interconnector 150) of the interconnector 150. The air electrode side current collecting member 134 located on the surface of the lower side) is electrically connected to the air electrode 114 of the single cell 110 constituting another power generation unit 102.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2, 4 and 7, the oxidant gas is passed through 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 the OG is supplied, the oxidant gas OG is delivered 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 through hole 107 for the flow path of the lower end plate 106. Is supplied to the air chamber 166 from the oxidant gas introduction manifold 161 via the oxidant gas supply communication flow path 132 of each power generation unit 102. Further, as shown in FIGS. 3, 5 and 8, the fuel gas is passed 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 the FG is supplied, the fuel gas FG is supplied to the fuel gas introduction manifold 171 via the branch portion 29 of the gas passage member 27, the main body portion 28, and the through hole 107 for the flow path of the lower end plate 106. Then, it is supplied from the fuel gas introduction manifold 171 to the fuel chamber 176 via the fuel gas supply communication flow path 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 are supplied. Power is generated by an electrochemical reaction with. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air pole 114 of the single cell 110 is electrically connected to one of the interconnectors 150 via the air pole side current collector 134, and the fuel pole 116 is via the fuel pole side current collector 144. It is electrically connected to the other interconnector 150. Further, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates electricity at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is a heater (for example, until the high temperature can be maintained by the heat generated by the power generation after the start-up. (Not shown) may be heated.

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 flow path 133 as shown in FIGS. 2, 4 and 7. Then, it is connected to the branch portion 29 via the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the through hole 107 for the flow path of the lower end plate 106 and the oxidant gas discharge manifold 162. It is discharged to the outside of the fuel cell stack 100 via the 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 flow path 143 as shown in FIGS. 3, 5, and 8. Further, it was connected to the branch portion 29 via the through hole 107 for the flow path of the lower end plate 106, 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. It is discharged to the outside of the fuel cell stack 100 via a gas pipe (not shown).

In each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment, the main flow direction of the oxidizing agent gas OG in the air chamber 166 (as shown in FIG. 7, from the X-axis positive direction side to the X-axis negative direction side). (Direction toward) and the main flow direction of the fuel gas FG in the fuel chamber 176 (direction from the negative X-axis side to the positive X-axis side as shown in FIG. 8) are substantially opposite directions (directions facing each other). ). That is, the power generation unit 102 (fuel cell stack 100) of the present embodiment is a counterflow type SOFC.

A-3. Detailed configuration of the fuel electrode side current collector 144:
Next, the detailed configuration of the fuel electrode side current collector 144 will be described. As shown in FIGS. 4 to 6 and 8, the fuel pole side current collecting member 144 has an interconnector facing portion 146, a plurality of fuel pole facing portions 145, and a plurality of connecting portions 147.

The interconnector facing portion 146 of the fuel pole side current collector 144 is in contact with the surface of the interconnector 150 (or the end plate 106, the same applies hereinafter) on the side facing the fuel pole 116, and is electrically connected to the interconnector 150. It is a plate-shaped part. The interconnector facing portion 146 is formed with a plurality of through holes 40 that penetrate the interconnector facing portion 146 in the thickness direction (that is, extend in the Z-axis direction). The interconnector facing portion 146 of the fuel electrode side current collecting member 144 corresponds to the first interconnector facing portion in the claims.

Each fuel pole facing portion 145 of the fuel pole side current collecting member 144 is in contact with the surface of the fuel pole 116 opposite to the side facing the electrolyte layer 112, and has a plate shape that is electrically connected to the fuel pole 116. It is a part. The shape of each fuel pole facing portion 145 in the Z-axis direction is substantially rectangular. Further, the plurality of fuel electrode facing portions 145 are arranged in a grid pattern along the X direction and the Y direction in the Z-axis direction. Each fuel electrode facing portion 145 is arranged so as to overlap the interconnector facing portion 146 in the Z-axis direction. The end 43 on the negative direction side of the Y axis of each fuel electrode facing portion 145 is a free end. The fuel pole facing portion 145 of the fuel pole side current collecting member 144 corresponds to the first electrode facing portion in the claims.

Each connecting portion 147 of the fuel electrode side current collecting member 144 is a plate connecting the end portion 42 on the negative direction side of the Y axis in each fuel electrode facing portion 145 and the end portion 41 facing the through hole 40 in the interconnector facing portion 146. It is a shaped part. The connecting portion 147 of the fuel electrode side current collecting member 144 corresponds to the first connecting portion within the scope of the claims.

As described above, the fuel pole side current collecting member 144 includes an interconnector facing portion 146 electrically connected to the interconnector 150, and a plurality of fuel pole facing portions 145 electrically connected to the fuel pole 116, respectively. Since it has a connecting portion 147 connecting the fuel pole facing portion 145 and the interconnector facing portion 146, the fuel pole 116 and the interconnector 150 are electrically connected as described above.

The fuel electrode side current collector 144 having such a configuration is completed, for example, by punching a flat plate material for manufacturing the fuel electrode side current collector 144, as shown in the partially enlarged view in FIG. In the state, cuts are made in each of the three sides of the rectangular region that becomes each fuel pole facing portion 145 and each connecting portion 147, and then the flat plate material after punching is bent to form each fuel pole facing portion. It can be manufactured by forming 145 and each connecting portion 147. In the partially enlarged view of FIG. 8, in order to show the method of manufacturing the fuel electrode side current collector member 144, a part of the state before the bending process is shown.

A fuel pole side spacer 149 made of, for example, a metal such as stainless steel is arranged between each fuel pole facing portion 145 and the interconnector facing portion 146 of the fuel pole side current collecting member 144. Due to the presence of the fuel electrode side spacer 149, 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 via the fuel electrode side current collector 144. A good electrical connection with the 150 (or end plate 106) is maintained.

Here, as shown in FIG. 6, in the power generation unit 102 of the present embodiment, the fuel electrode side current collecting member 144 is fixed to the interconnector 150 by being joined to the interconnector 150 by laser welding. More specifically, by performing laser welding from the surface (lower surface in this embodiment) of the interconnector 150 opposite to the side facing the fuel electrode side current collecting member 144, the interconnector 150 and the fuel electrode side current collector are collected. A fuel pole side welded portion (melted portion) 47 is formed at a position where the member 144 comes into contact with the interconnector 150, the fuel pole side current collecting member 144, and the fuel pole side spacer 149 and the interconnector facing portion 146. .. A part of the fuel electrode side welded portion 47 is exposed on the surface of the member to be welded, specifically, the lower surface of the interconnector 150 (in the present embodiment, the coat 151 is formed on the surface of the interconnector 150). Therefore, a part of the fuel electrode side welded portion 47 is exposed on the surface of the coat 151). The fuel electrode side welded portion 47 corresponds to the first welded portion within the scope of the claims. In the present embodiment, the fuel electrode side welded portion 47 is continuously formed from the vicinity of one end to the vicinity of the other end of the fuel electrode side current collecting member 144 along the X-axis direction. In the present embodiment, the fuel pole side welded portion 47 penetrates the interconnector facing portion 146 of the fuel pole side current collecting member 144 and enters the fuel pole side spacer 149, but the fuel pole facing portion 145. Has not been reached. That is, the end portion of the fuel pole side welded portion 47 on the fuel pole facing portion 145 side is separated from the fuel pole facing portion 145.

As described above, the fuel electrode side welded portion 47 is formed by performing laser welding from the surface (lower surface in the present embodiment) opposite to the side facing the fuel electrode side current collecting member 144 in the interconnector 150. Therefore, the diameter D11 of the interconnector 150 at the position of the surface (lower surface) of the fuel electrode side welded portion 47 is larger than the diameter D12 at the position of the surface (upper surface) on the opposite side of the interconnector 150. A part (bead) of the fuel electrode side welded portion 47 protrudes from the surface (lower surface) of the interconnector 150.

A-4. Detailed configuration of the air electrode side current collector 134:
Next, the detailed configuration of the air electrode side current collecting member 134 will be described. As shown in FIGS. 4 to 7, the air pole side current collecting member 134 has an interconnector facing portion 136, a plurality of air pole facing portions 135, and a plurality of connecting portions 137.

The interconnector facing portion 136 of the air electrode side current collecting member 134 is in contact with the surface of the interconnector 150 (or the end plate 104, the same applies hereinafter) on the side facing the air pole 114, and is electrically connected to the interconnector 150. It is a plate-shaped part. A plurality of through holes 30 that penetrate the interconnector facing portion 136 in the thickness direction (that is, extend in the Z-axis direction) are formed in the interconnector facing portion 136. As shown in FIG. 7, in the present embodiment, each through hole 30 formed in the interconnector facing portion 136 is a hole having a long shape in the X-axis direction. Further, in the interconnector facing portion 136, the plurality of through holes 30 are arranged so as to be arranged in the Y-axis direction. The interconnector facing portion 136 of the air electrode side current collecting member 134 corresponds to the second interconnector facing portion in the claims.

Each air pole facing portion 135 of the air pole side current collecting member 134 is in contact with the surface of the air pole 114 on the side opposite to the side facing the electrolyte layer 112, and has a plate shape that is electrically connected to the air pole 114. It is a part. The shape of each air electrode facing portion 135 in the Z-axis direction is substantially rectangular. Further, the plurality of air electrode facing portions 135 are arranged in a grid pattern along the X direction and the Y direction in the Z-axis direction. Each air electrode facing portion 135 is arranged so as to overlap the through hole 30 formed in the interconnector facing portion 136 in the Z-axis direction. The end 33 on the positive direction side of the Y axis of each air electrode facing portion 135 is a free end. The air electrode facing portion 135 of the air electrode side current collecting member 134 corresponds to the second electrode facing portion in the claims.

Each connecting portion 137 of the air electrode side current collecting member 134 has an end portion 32 on the negative direction side of the Y axis of each air electrode facing portion 135 and an end portion 31 facing the through hole 30 of the interconnector facing portion 136. It is a plate-shaped part to be tied. The connecting portion 137 of the air electrode side current collecting member 134 corresponds to the second connecting portion within the scope of the claims.

As described above, the air electrode side current collecting member 134 includes an interconnector facing portion 136 electrically connected to the interconnector 150, and a plurality of air electrode facing portions 135 electrically connected to the air electrode 114, respectively. Since it has a connecting portion 137 connecting the air electrode facing portion 135 and the interconnector facing portion 136, the air electrode 114 and the interconnector 150 are electrically connected as described above.

The air electrode side current collecting member 134 having such a configuration is formed by punching, for example, a flat plate member for manufacturing the air electrode side current collecting member 134, so that each air electrode facing portion 135 and each connecting portion 135 are connected in a completed state. A hole corresponding to the outer shape of each through hole 30 is formed while leaving a portion to be a portion 137, and then the flat plate member after the hole is bent to perform an air electrode facing portion 135 and each connecting portion 137. Can be produced by forming.

An air pole side spacer 139 is arranged between each air pole facing portion 135 of the air pole side current collecting member 134 and the interconnector 150. The air electrode side spacer 139 is a member having a substantially rectangular parallelepiped shape, and is formed of an elastic material (elastic body) such as mica. As shown in FIGS. 6 and 7, each air electrode side spacer 139 has a shape extending from the surface of the interconnector 150 to the surface of each air electrode facing portion 135 in the Z-axis direction. A part of each air electrode side spacer 139 on the interconnector 150 side is housed in a through hole 30 formed in the interconnector facing portion 136 of the air electrode side current collecting member 134. Due to the presence of the air electrode side spacer 139, the air electrode side current collecting member 134 follows the deformation of the power generation unit 102 due to the temperature cycle and the reaction gas pressure fluctuation, and the air electrode 114 and the interconnector via the air electrode side current collecting member 134. A good electrical connection with the 150 (or end plate 104) is maintained. Further, the presence of the air electrode side spacer 139 can relieve the stress in the Z-axis direction applied to the single cell 110, and can suppress the occurrence of damage (cracking, etc.) of the single cell 110.

Here, as shown in FIG. 6, in the power generation unit 102 of the present embodiment, the air electrode side current collecting member 134 is fixed to the interconnector 150 by being joined to the interconnector 150 by laser welding. More specifically, by performing laser welding from the surface (upper surface in this embodiment) of the interconnector 150 opposite to the side facing the air electrode side current collecting member 134, the interconnector 150 and the air electrode side current collector are collected. An air electrode side welded portion (melted portion) 37 is formed at a position where the member 134 is in contact with the interconnector 150 and the interconnector facing portion 136 of the air electrode side current collecting member 134. A part of the air electrode side welded portion 37 is exposed on the surface of the member to be welded, specifically, the upper surface of the interconnector 150. The air electrode side welded portion 37 corresponds to the second welded portion within the scope of the claims. In the present embodiment, the air electrode side welded portion 37 is continuously formed from the vicinity of one end to the vicinity of the other end of the air electrode side current collector 134 along the X-axis direction.

As described above, the air electrode side welded portion 37 is formed by performing laser welding from the surface (upper surface in the present embodiment) opposite to the side of the interconnector 150 facing the air electrode side current collecting member 134. Therefore, the diameter D21 at the position of the surface (lower surface) of the interconnector 150 opposite to the surface of the air electrode side welded portion 37 is smaller than the diameter D22 at the position of the surface (upper surface) of the interconnector 150. It has become. Further, a part (bead) of the air electrode side welded portion 37 protrudes from the surface (upper surface) of the interconnector 150.

A-5. Effect of this embodiment:
As described above, each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment includes a single cell 110, an interconnector 150, a fuel pole side current collector 144, and a fuel pole side spacer 149. .. The single cell 110 includes an electrolyte layer 112, and air poles 114 and fuel poles 116 that face each other in the Z-axis direction with the electrolyte layer 112 interposed therebetween. The interconnector 150 is a metal member arranged so as to face the fuel electrode 116. The fuel electrode side current collecting member 144 is a metal member arranged between the interconnector 150 and the fuel electrode 116, and has an interconnector facing portion 146 electrically connected to the interconnector 150 and a fuel electrode 116. Includes a fuel electrode facing portion 145 electrically connected to and a connecting portion 147 connecting the interconnector facing portion 146 and the fuel electrode facing portion 145. The fuel pole side spacer 149 is a metal member arranged between the interconnector facing portion 146 and the fuel pole facing portion 145 of the fuel pole side current collecting member 144. Further, in the power generation unit 102 of the present embodiment, the interconnector 150, the interconnector facing portion 146 of the fuel pole side current collector 144, and the fuel pole side spacer are located at positions where the interconnector 150 and the fuel pole side current collector 144 are in contact with each other. A fuel electrode side welded portion 47 for joining with 149 is formed. Since the power generation unit 102 of the present embodiment has the above-described configuration, it is possible to improve the electrical connectivity between the fuel electrode 116 and the interconnector 150, and by extension, the power generation unit 102. The electrical performance of the can be improved.

As shown in FIG. 6, in the power generation unit 102 of the present embodiment, as a conductive path between the fuel electrode 116 and the interconnector 150, the fuel electrode 116 to the fuel electrode facing portion 145 of the fuel electrode side current collecting member 144 There is a first conductive path EP1 that leads to the interconnector 150 through the articulating portion 147 and the interconnector facing portion 146. Further, in the power generation unit 102 of the present embodiment, the fuel pole side that joins the metal interconnector 150, the interconnector facing portion 146 of the metal fuel pole side current collecting member 144, and the metal fuel pole side spacer 149. Since the welded portion 47 is formed, as a conductive path between the fuel pole 116 and the interconnector 150, the fuel pole facing portion 145 of the fuel pole side current collecting member 144, the fuel pole side spacer 149, and the fuel There is also a second conductive path EP2 that passes through the pole-side weld 47 to the interconnector 150. As described above, according to the power generation unit 102 of the present embodiment, the presence of the fuel electrode side welded portion 47 can increase the conductive path between the fuel electrode 116 and the interconnector 150, so that the fuel electrode 116 and the interconnector can be increased. The electrical connectivity with the connector 150 can be improved, and as a result, the electrical performance of the power generation unit 102 can be improved. Further, according to the power generation unit 102 of the present embodiment, the presence of the fuel electrode side welded portion 47 can prevent the fuel electrode side spacer 149 from being displaced with respect to the fuel electrode side current collecting member 144. It is possible to suppress a decrease in electrical connectivity between the fuel electrode side current collecting member 144 and the fuel electrode 116 and the interconnector 150 due to the displacement of the fuel electrode side spacer 149.

Further, in the power generation unit 102 of the present embodiment, the end portion of the fuel pole side current collecting member 144 in the fuel pole side welded portion 47 on the fuel pole facing portion 145 side is separated from the fuel pole facing portion 145. Therefore, in the power generation unit 102 of the present embodiment, the fuel pole side spacer 149 and the fuel pole facing portion 145 of the fuel pole side current collector 144 are not joined, and the fuel pole side spacer 149 and the single cell 110 (fuel pole) are not joined. The position of the fuel electrode facing portion 145 is variable with and from 116). Therefore, according to the power generation unit 102 of the present embodiment, the vertical stress applied to the single cell 110 can be effectively relieved by the presence of the fuel electrode facing portion 145 whose position is variable, and the single cell 110 can be effectively relieved. The occurrence of damage (cracking, etc.) can be effectively suppressed.

Further, the power generation unit 102 of the present embodiment further collects metal air poles on the surface of the interconnector 150, which is in contact with the other surface on the opposite side to the one surface with which the fuel electrode side current collecting member 144 is in contact. It includes an electric member 134. Further, an air electrode side welded portion 37 for joining the interconnector 150 and the air electrode side current collecting member 134 is formed at a position where the interconnector 150 and the air electrode side current collecting member 134 are in contact with each other. Therefore, in the power generation unit 102 of the present embodiment, as a conductive path between the air electrode 114 and the interconnector 150, the air electrode facing portion 135 of the air electrode side current collecting member 134, the connecting portion 137, and the interconnector There is a conductive path through the facing portion 136 and the air electrode side welded portion 37 to the interconnector 150. Therefore, according to the power generation unit 102 of the present embodiment, the conductive path between the air electrode 114 and the interconnector 150 can be increased, and the electrical connectivity between the air electrode 114 and the interconnector 150 is improved. As a result, the electrical performance of the power generation unit 102 can be further improved.

Further, in the power generation unit 102 of the present embodiment, the diameter D11 at the position of one surface (lower surface) of the interconnector 150 in the fuel electrode side welded portion 47 is the diameter at the position of the other surface (upper surface) of the interconnector 150. The diameter D21 at the position of the one surface (lower surface) of the interconnector 150 in the welded portion 37 on the air electrode side, which is larger than D12, is larger than the diameter D22 at the position of the other surface (upper surface) of the interconnector 150. small. This means that the direction of laser welding when forming the fuel electrode side welded portion 47 (welding is performed from the lower surface side of the interconnector 150) is the direction of laser welding when forming the air electrode side welded portion 37 (inter). Welding is performed from the upper surface side of the connector 150), which means that the direction is opposite. Therefore, according to the power generation unit 102 of the present embodiment, it is possible to suppress the occurrence of warpage in the interconnector 150 due to the provision of the fuel electrode side welded portion 47 and the air electrode side welded portion 37.

B. Second embodiment:
FIG. 9 is an explanatory diagram schematically showing the configuration of the power generation unit 102a in the second embodiment. FIG. 9 shows the YZ cross-sectional configuration of the power generation unit 102a of the second embodiment corresponding to the YZ cross-sectional configuration of the power generation unit 102 of the first embodiment shown in FIG. In the following, among the configurations of the power generation unit 102a of the second embodiment, the same configurations as the configurations of the power generation unit 102 of the first embodiment described above will be appropriately described by adding the same reference numerals.

As shown in FIG. 9, the power generation unit 102a of the second embodiment is mainly different from the power generation unit 102 of the first embodiment in the configuration of the welded portion. Specifically, in the power generation unit 102a of the second embodiment, in addition to the interconnector 150 and the fuel pole side current collecting member 144, a common welded portion 57 that integrally joins the air pole side current collecting member 134 is formed. ing. More specifically, the common welded portion 57 includes an interconnector facing portion 136 of the air pole side current collecting member 134, an interconnector 150, an interconnector facing portion 146 of the fuel pole side current collecting member 144, and a fuel pole side spacer 149. It is formed to join. Such a common welded portion 57 performs laser welding from, for example, a surface (lower surface in the present embodiment) of the current collector member 134 on the air electrode side opposite to the side facing the interconnector 150 in the interconnector facing portion 136. Can be formed by A part of the common welded portion 57 is exposed on the surface of the member to be welded, specifically, the lower surface of the interconnector facing portion 136 of the air electrode side current collecting member 134. The common weld 57 corresponds to the first weld in the claims.

As described above, in the power generation unit 102a of the second embodiment, the common welded portion 57 is formed so as to join the air electrode side current collecting member 134, the interconnector 150, and the fuel electrode side current collecting member 144. Therefore, according to the power generation unit 102a of the present embodiment, due to the presence of the common welded portion 57, the conductive path EP3 between the air electrode 114 and the interconnector 150 is provided in addition to the space between the fuel electrode 116 and the interconnector 150. Since it can be increased, it is possible to improve the electrical connectivity between the air pole 114 and the interconnector 150 in addition to between the fuel pole 116 and the interconnector 150, and as a result, the electricity of the power generation unit 102a. Performance can be further improved. Further, in the power generation unit 102a of the second embodiment, two welded portions (fuel electrode side welded portion 47 and air pole side welded portion 37) are not provided as in the first embodiment, but one (common welded portion) is provided. Since only 57) needs to be provided, it is possible to simplify the device configuration and improve the efficiency of the manufacturing process.

Further, in the power generation unit 102a of the second embodiment, the common welded portion 57 is formed so as to join the interconnector facing portion 136 of the air pole side current collecting member 134, the interconnector 150, and the fuel pole side current collecting member 144. Has been done. Therefore, it is possible to prevent the common welded portion 57 from projecting to the other single cell 110 side facing the interconnector 150 with the air electrode side current collecting member 134 sandwiched therein, and the single cell 110 is the common welded portion 57. It is possible to prevent damage (cracking, etc.) from occurring in the single cell 110 due to interference with the single cell 110.

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

The configuration of the power generation unit 102 or the fuel cell stack 100 of the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, the end portion of the fuel pole side welded portion 47 on the fuel pole facing portion 145 side is separated from the fuel pole facing portion 145, but the fuel pole facing portion 145 side of the fuel pole side welded portion 47 is separated. It may be assumed that the end portion reaches the fuel electrode facing portion 145.

Further, in the first embodiment, the direction of laser welding when forming the fuel electrode side welded portion 47 and the direction of laser welding when forming the air electrode side welded portion 37 are opposite to each other. It may be in the same orientation. Further, in the first embodiment, two welds of the fuel electrode side welded portion 47 and the air electrode side welded portion 37 are formed, but one of them may not be formed.

Further, the configuration (shape, material, etc.) of the fuel electrode side current collector member 144 and the fuel electrode side spacer 149, and the configuration (shape, material, etc.) of the air electrode side current collector member 134 and the air electrode side spacer 139 in the above embodiment. Is just an example and can be modified in various ways.

Further, in the above embodiment, the interconnector 150 is covered with the coat 151, but the interconnector 150 may not be covered with the coat 151. Similarly, in the above embodiment, the air electrode side current collecting member 134 is covered with the coat 38, but the air electrode side current collecting member 134 may not be covered with the coat 38. Further, in the above embodiment, the bonding layer 138 is interposed between the air electrode side current collecting member 134 and the air electrode 114, but the bonding layer 138 is interposed between the air electrode side current collecting member 134 and the air electrode 114. May not intervene.

Further, in the above embodiment, the bolt holes 109 are provided independently of the communication holes 108 for each manifold, but the independent bolt holes 109 are not provided, and the communication holes 108 for each manifold are used as bolt holes. May also be used. Further, in the above embodiment, a counterflow type in which the main flow direction of the oxidant gas OG in the air chamber 166 and the main flow direction of the fuel gas FG in the fuel chamber 176 are substantially opposite directions is described as an example. However, the present invention is also applicable to other types (such as a coflow type in which the two flow directions are substantially the same, a cross flow type in which the two flow directions intersect, and the like).

Further, in the above embodiment, the number of power generation units 102 included in the fuel cell stack 100 is only an example, and the number of power generation units 102 is appropriately determined according to the output voltage and the like required for the fuel cell stack 100. Further, in the above embodiment, an intermediate layer may be arranged between the air electrode 114 and the electrolyte layer 112. Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

Further, in the above embodiment, the configuration of the current collecting member, the welded portion, etc. on the air electrode side may be the same as the configuration on the fuel electrode side. For example, the air electrode side spacer 139 is a metal member arranged between the interconnector facing portion 136 and the air electrode facing portion 135 of the air electrode side current collecting member 134, and is a metal member arranged between the interconnector 150 and the air electrode side collecting member 134. A welded portion that joins the interconnector 150, the interconnector facing portion 136 of the air electrode side current collecting member 134, and the air electrode side spacer 139 may be formed at a position where the electric member 134 comes into contact with the electric member 134. In this case, the air electrode 114 corresponds to the first electrode in the claims.

Further, in the above embodiment, the SOFC that generates power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidizing agent gas is targeted, but the present invention comprises an electrolysis reaction of water. It is also applicable to an electrolytic cell unit, which is a constituent unit of a solid oxide fuel cell (SOEC) that uses it to generate hydrogen, and an electrolytic cell stack having a plurality of electrolytic cell units. The configuration of the electrolytic cell stack is not described in detail here because it is known as described in, for example, Japanese Patent Application Laid-Open No. 2016-81813, but is generally the same as the fuel cell stack 100 in the above-described embodiment. 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, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the voltage is applied through the communication hole 108. Water vapor as a raw material gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolytic cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out to the outside of the electrolytic cell stack through the communication hole 108. Even in the electrolytic cell unit and the electrolytic cell stack having such a configuration, if the configuration of the current collecting member, the welded portion, etc. having the same configuration as that of the above embodiment is adopted, the electrical connectivity between the electrode and the interconnector is improved. As a result, the electrical performance of the electrolytic cell unit can be improved.

22: Bolt 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 30: Through hole 31: End 32: End 33: End 37: Air pole side weld 38: Coat 40: Through hole 41: End 42: End 43: End 47: Fuel pole side weld 57: Common weld 100: Fuel cell stack 102: Fuel cell power generation unit 104: End plate 106: End plate 107: Through hole for flow path 108: Communication hole 109: Bolt hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: Fuel pole 120: Separator 121: Hole 124: Joint 130: Air pole side frame 131: Hole 132: Oxidating agent gas supply communication Flow path 133: Oxidizing agent gas discharge communication flow path 134: Air pole side current collecting member 135: Air pole facing part 136: Interconnector facing part 137: Connecting part 138: Bonding layer 139: Air pole side spacer 140: Fuel pole side Frame 141: Hole 142: Fuel gas supply communication flow path 143: Fuel gas discharge communication flow path 144: Fuel pole side current collecting member 145: Fuel pole facing part 146: Interconnector facing part 147: Connecting part 149: Fuel pole side spacer 150: Interconnector 151: Coat 161: Oxidizing agent gas introduction manifold 162: Oxidizing agent gas discharge manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber

Claims (7)

An electrochemical reaction single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in the first direction across the electrolyte layer.
A metal interconnector arranged so as to face the first electrode, which is one of the air electrode and the fuel electrode.
A first metal current collecting member arranged between the interconnector and the first electrode, the first interconnector facing portion electrically connected to the interconnector, and the first interconnector. A first electrode comprising a first electrode facing portion electrically connected to the electrode 1 and a first connecting portion connecting the first interconnector facing portion and the first electrode facing portion. With the current collector
In the electrochemical reaction unit, further
A metal spacer arranged between the first interconnector facing portion and the first electrode facing portion of the first current collecting member is provided.
At a position where the interconnector and the first current collecting member are in contact with each other, a first welded portion for joining the interconnector, the first interconnector facing portion of the first current collecting member, and the spacer is formed. Formed,
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 1,
The end portion of the first current collecting member in the first welded portion on the side facing the first electrode is separated from the first electrode facing portion.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 1 or 2, further
A second metal current collecting member in contact with the other surface of the surface of the interconnector, which is opposite to the one surface with which the first current collecting member is in contact, is provided.
The first welded portion is formed so as to join the second current collecting member, the interconnector, and the first current collecting member.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 3,
The second current collecting member is
A plate-shaped second interconnector facing portion electrically connected to the interconnector,
A plate-shaped second electrode facing portion electrically connected to a second electrode which is the other of the air electrode and the fuel electrode of the electrochemical reaction single cell included in the other electrochemical reaction unit.
A second connecting portion connecting the second interconnector facing portion and the second electrode facing portion,
Including
The first welded portion is formed so as to join the second interconnector facing portion of the second current collector member, the interconnector, and the first current collector member.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 1 or 2, further
A second metal current collecting member in contact with the other surface of the surface of the interconnector, which is opposite to the one surface with which the first current collecting member is in contact, is provided.
A second welded portion for joining the interconnector and the second current collecting member is formed at a position where the interconnector and the second current collecting member come into contact with each other.
The diameter of the interconnector at the position of one surface of the first welded portion is larger than the diameter of the interconnector at the position of the other surface of the interconnector, and the diameter of the interconnector at the position of the other surface of the interconnector is larger than that of the interconnector. The diameter at the position of one surface is smaller than the diameter at the position of the other surface of the interconnector.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to any one of claims 1 to 5.
The electrochemical reaction single cell is a fuel cell single cell.
An electrochemical reaction unit characterized by that. In an electrochemical reaction cell stack having a plurality of electrochemical reaction units arranged side by side in the first direction.
The electrochemical reaction cell stack, wherein at least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to any one of claims 1 to 6.

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