JP6835768B2 - 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, also simply referred to as “power generation unit”), which is a constituent unit of the SOFC, includes a fuel cell single cell (hereinafter, also simply referred to as “single cell”). The single cell includes an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode that face each other in a predetermined direction (hereinafter, referred to as “first direction”) across the electrolyte layer. The air electrode includes, for example, a perovskite-type oxide. Further, the fuel electrode contains an electron conductive substance (for example, nickel (hereinafter referred to as "Ni")) and an oxide ion conductive ceramic (for example, yttria-stabilized zirconia (hereinafter referred to as "YSZ")). (See, for example, Patent Document 1).

The power generation unit further includes a current collector and an interconnector. The current collector is a conductive current collector that is arranged between the specific electrode and the interconnector in the first direction and electrically connects the specific electrode and the interconnector. Further, the current collector includes a plurality of electrode facing portions in contact with the surface of the specific electrode facing the current collector, and a plurality of interconnector facing portions in contact with the surface of the interconnector facing the current collector. And a connecting portion that connects the electrode facing portion and the interconnector facing portion. The current collector is electrically connected to the fuel electrode and the interconnector by the electrode facing portion, the connecting portion, and the interconnector facing portion to ensure conductivity (electrical connection) between the two (for example, Patent Document). 2).

JP-A-2015-84281 International Publication 2013/021629

Generally, during the operation of SOFC, the generated gas generated by supplying the reaction gas to the fuel electrode or the air electrode as a specific electrode tends to stay in the gas chamber and hinder the further inflow of the reaction gas into the gas chamber. .. Therefore, there is a problem that the partial pressure of the reaction gas at the specific electrode decreases, which in turn causes a decrease in the reaction efficiency. Further, when the specific electrode is a fuel electrode, it is generated on the fuel electrode side by a reaction in a single cell, particularly in a portion of the surface of the fuel electrode that is in close contact with the surface of the electrode facing portion of the current collector. Water (water vapor) is hard to be discharged to the fuel chamber and stays on the surface of the fuel electrode, so that the water vapor partial pressure tends to increase. When the partial pressure of water vapor increases in a region of the fuel electrode, the microstructural change (aggregation) of Ni contained in the region of the fuel electrode is promoted. There is also a problem that such a microstructural change of Ni contained in the fuel electrode causes a decrease in the three-phase interface and causes a deterioration in the performance of the single cell.

It should be noted that such a problem is also common to the electrolytic cell unit, which 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. Is. That is, during the operation of the SOEC, the generated gas generated by supplying the reaction gas to the specific electrode tends to stay and hinder the inflow of further reaction gas. Therefore, the SOEC also has a problem that the partial pressure of the reaction gas at the specific electrode is lowered and the reaction efficiency is lowered, as in the SOFC. 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 SOFC and SOEC 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 electrolyte layer, an electrochemical reaction single cell including an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween. A conductive interconnector arranged on a specific electrode side of one of the fuel electrode and the air electrode with respect to the electrochemical reaction single cell, and the specific electrode and the interconnector in the first direction. A plurality of conductive current collectors arranged between the specific electrodes and electrically connecting the specific electrode and the interconnector, which are in contact with the surface of the specific electrode facing the current collector. A collection having an electrode facing portion, a plurality of interconnector facing portions in contact with the surface of the interconnector facing the current collector, and a connecting portion connecting the electrode facing portion and the interconnector facing portion. In an electrochemical reaction unit including an electric body and a spacer that contacts the surface of the electrode facing portion on the side facing the interconnector in the first direction, at least one of the electrode facing portions has the specific electrode. A first defect space facing the electrode is formed, and the first defect space communicates with a gas chamber facing a portion of the specific electrode that does not face the electrode facing portion. As described above, according to the present electrochemical reaction unit, the first defect space facing the specific electrode is formed in the electrode facing portion of the current collector that is in contact with the surface of the specific electrode facing the current collector. Since it is formed, the generated gas generated in the region of the specific electrode in contact with the electrode facing portion can be satisfactorily discharged to the gas chamber facing the specific electrode through the first defect space. .. Therefore, it is possible to suppress the retention of the generated gas generated by supplying the reaction gas to the specific electrode, facilitate the inflow of the reaction gas into the gas chamber, and efficiently carry out the reaction in a single cell. .. In addition, when the specific electrode is the fuel electrode, in this electrochemical reaction unit, the retention of water vapor is suppressed in the region of the fuel electrode in contact with the electrode facing portion of the current collector on the fuel electrode side, and the water vapor is vaporized. The increase in partial pressure can be suppressed. Therefore, in this electrochemical reaction unit, it is possible to suppress the occurrence of microstructural changes in Ni due to an increase in the partial pressure of water vapor, and by extension, it is possible to suppress deterioration in the performance of a single cell.

(2) In the electrochemical reaction unit, the first defect space may be configured to directly communicate with the gas chamber. As described above, in the present electrochemical reaction unit, the generated gas staying in the first defective space can be directly discharged to the gas chamber. Therefore, in this electrochemical reaction unit, the reaction in a single cell can be carried out more efficiently.

(3) In the electrochemical reaction unit, the first defect space is directly communicated with the gas chamber on the boundary side with the connecting portion at the electrode facing portion, and is on the connecting portion side of the spacer. The end face is separated from the connecting portion on the electrode facing portion side, and the separating space formed between the end face of the spacer separated from the connecting portion and the connecting portion is the first defect space. It may be configured to directly communicate with the gas chamber and directly communicate with the gas chamber. As described above, according to the present electrochemical reaction unit, the generated gas staying in the first defect space can be discharged to the gas chamber through the separation space formed between the end face of the spacer and the connecting portion. it can. As a result, it is possible to further suppress the retention of the generated gas in the region of the specific electrode that is in contact with the electrode facing portion of the current collector. Further, since this separated space communicates with the first defective space, the reaction gas easily diffuses into the first defective space. As a result, the reaction at the specific electrode facing the first defective space can be promoted, and the generated gas staying in the first defective space can be easily discharged to the gas chamber. Therefore, in this electrochemical reaction unit, the reaction in a single cell can be carried out more efficiently.

(4) In the electrochemical reaction unit, a second defective space facing the gas chamber is formed in the connecting portion, and the second defective space directly communicates with the first defective space. It may be configured as such. As described above, according to the present electrochemical reaction unit, the produced gas staying in the first defective space can be effectively discharged to the gas chamber through the second defective space. Therefore, in this electrochemical reaction unit, the reaction in a single cell can be carried out more efficiently.

(5) In the electrochemical reaction unit, the second defect space is a virtual extension in which the surface of the surface of the interconnector facing portion facing the spacer is extended in a direction substantially orthogonal to the first direction. It may be configured to be separated from the surface. Therefore, according to the present electrochemical reaction unit, the generated gas staying in the first defective space can be effectively discharged to the gas chamber, and the strength at the connecting portion of the current collector can be secured. .. Therefore, in the present electrochemical reaction unit, the reaction in a single cell can be carried out more efficiently, and the strength at the connecting portion of the current collector can be secured.

(6) In the electrochemical reaction unit, the first defect space may be formed in a region including the center point of the electrode facing portion in the first directional view. The generated gas generated by the reaction at the specific electrode is difficult to be discharged into the gas chamber and tends to stay in the region including the center point of the electrode facing portion, which is the surface in contact with the specific electrode. According to the present electrochemical reaction unit, by forming the first defect space in the region including the center point of the electrode facing portion, the generated gas can be easily discharged to the gas chamber, and the specific electrode faces the electrode. It is possible to reduce the retention of the generated gas between the parts. Therefore, in the present electrochemical reaction unit, the reaction in a single cell can be carried out more efficiently, and the performance deterioration of the single cell can be further suppressed.

(7) In the electrochemical reaction unit, the first defect space may be directly communicated with a gas flow path space extending substantially parallel to the main flow direction of gas in the gas chamber. According to this electrochemical reaction unit, since the first defective space is directly communicated with the gas flow path space in the gas chamber, the generated gas staying in the first defective space is discharged to the gas chamber more efficiently. can do. Therefore, in the present electrochemical reaction unit, the reaction in the single cell can be carried out more efficiently, and the performance deterioration of the single cell 110 can be further suppressed.

(8) In the electrochemical reaction unit, at least a part of other current collectors facing the current collector across the electrochemical reaction single cell is in the electrode facing portion in the first directional view. The configuration may be arranged so as to overlap at least a part of two regions facing each other in a predetermined direction with the first defect space in between. On the other hand, another current collector facing the current collector with a single cell sandwiched overlaps the two regions facing in a predetermined direction with the first defect space in the electrode facing portion sandwiched in the first directional view. If this is not the case, stress may be concentrated near the edges of other current collectors in the single cell, causing cell cracking and the like. Since the above-mentioned configuration is adopted in this electrochemical reaction unit, stress concentration occurs in a single cell when assembling a plurality of single cells to form an electrochemical reaction cell stack or during operation of the electrochemical reaction cell stack. It reduces the occurrence of performance degradation due to cell cracking.

(9) In the electrochemical reaction unit, the first defect space is formed in the electrode facing portion so that the electrode facing portion has a U shape in the first directional view. In the first directional view, at least one corner portion of the portion of the electrode facing portion forming the first defect space may have an R shape. According to this electrochemical reaction unit, when processing a current collector, at least one corner portion of the portion of the electrode facing portion forming the first defect space is formed into an R shape. It is possible to reduce the occurrence of stress concentration at the corners during the operation of the electrochemical reaction cell stack, and to reduce the occurrence of cracks starting from the corners where the stress is concentrated.

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 an electrolytic cell unit), electricity including 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 YZ 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 YZ 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 XY cross-sectional structure of the power generation unit 102 at the position of VI-VI of FIG. 4 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 FIG. 4 and FIG. It is an XZ sectional view which shows the detailed structure of the fuel electrode side current collector 144. It is a YZ cross-sectional view which shows the detailed structure of the fuel electrode side current collector 144. It is XY cross-sectional view which shows the detailed structure of the fuel electrode side current collector 144. It is XZ sectional view and XY sectional view which shows the detailed structure of the fuel electrode side current collector 144 in the modification. It is an XZ sectional view and a YZ sectional view which show the detailed structure of the fuel pole side current collector 144 in the modification. It is XY sectional view which shows the detailed structure of the fuel electrode side current collector 144 in the modification. It is XY sectional view which shows the detailed structure of the fuel electrode side current collector 144 in the modification.

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 in the present embodiment, and FIG. 2 is an explanatory view showing an XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II of FIG. FIG. 3 is an explanatory view showing a YZ cross-sectional configuration of the fuel cell stack 100 at the position III-III of FIG. 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.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cell power generation unit (hereinafter, referred to as “power generation unit”) 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 this 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 fuel cell stack 100 corresponds to the electrochemical reaction cell stack in the claims, the power generation unit 102 corresponds to the electrochemical reaction unit in the claims, and the arrangement direction (vertical direction) is patented. Corresponds to the first direction in the claims.

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

A bolt 22 extending in the vertical direction is inserted into each communication hole 108, and the fuel cell stack 100 is fastened by the bolt 22 and the nuts 24 fitted on both sides of the bolt 22. As shown in FIGS. 2 and 3, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 forming the upper end of the fuel cell stack 100, and the bolt. An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of the 22 and the lower surface of the end plate 106 forming the lower end of the fuel cell stack 100. However, in the place where the gas passage member 27 described later is provided, the insulating sheets arranged on the upper side and the lower side of the gas passage member 27 and the gas passage member 27 between the nut 24 and the surface of the end plate 106, respectively. 26 is intervening. 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.

The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication hole 108. Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108. As shown in FIGS. 1 and 2, near the midpoint of 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 of the fuel cell stack 100 around the Z-axis direction. In the space formed by the position bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted, the oxidant gas OG is introduced from the outside of the fuel cell stack 100, and the oxidant gas OG is introduced into each of the spaces. It functions as an oxidizer gas introduction manifold 161 which is a gas flow path supplied to the power generation unit 102, and is inside the side opposite to the side (the side on the negative direction side of the X axis among the two sides parallel to the Y axis). The space formed by the bolt 22 (bolt 22B) located near the point and the communication hole 108 through which the bolt 22B is inserted is an oxidizer off-gas OOG which is a gas discharged from the air chamber 166 of each power generation unit 102. Functions as an oxidant gas discharge manifold 162 that discharges the fuel cell stack 100 to the outside. In this embodiment, for example, air is used as the oxidant gas OG.

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

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow tubular main body 28 and a hollow tubular branch 29 branched from the side surface of the main body 28. 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. Further, as shown in FIG. 2, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22B forming the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162. Further, as shown in FIG. 3, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22D forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171 and fuel gas. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172.

(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.

(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 YZ cross-sectional structure of two power generation units 102. Further, FIG. 6 is an explanatory view showing an XY cross-sectional configuration of the power generation unit 102 at the position of VI-VI of FIGS. 4 and 5, and FIG. 7 is a power generation unit at the position of VII-VII of FIGS. 4 and 5. It is explanatory drawing which shows the XY cross-sectional structure of 102. Note that FIG. 7 shows an enlarged configuration of a part of the fuel electrode side current collector 144, which will be described later.

As shown in FIGS. 4 and 5, 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 144 and a pair of interconnectors 150 that form the uppermost layer and the lowermost layer of the power generation unit 102. Holes corresponding to the communication holes 108 through which the above-mentioned bolts 22 are inserted are formed on the peripheral edges of the separator 120, the air pole side frame 130, the fuel pole side frame 140, and the interconnector 150 around the Z-axis direction.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member. In this embodiment, the interconnector 150 is made of stainless steel. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents mixing of reaction gases 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 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 single cell 110 corresponds to an electrochemical reaction single cell within the scope of claims.

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 solid oxides such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxides. 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 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, Ni (nickel), a cermet composed of Ni and ceramic particles, a Ni-based alloy, or the like. 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 metal, for example. 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.

As shown in FIG. 6, 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. .. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. As shown in FIG. 4, the air electrode side frame 130 has a peripheral edge of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and a peripheral edge of the surface of the interconnector 150 facing the air electrode 114. It is in contact with the part. 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 hole 132 that communicates the oxidant gas introduction manifold 161 and the air chamber 166, and the oxidant gas that communicates the air chamber 166 and the oxidant gas discharge manifold 162. A discharge communication hole 133 is formed.

As shown in FIG. 7, the fuel electrode side frame 140 is a frame-shaped member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. Hole 141 of the fuel electrode side frame 140 constitutes a fuel chamber 176 facing the fuel electrode 116. As shown in FIG. 5, the fuel electrode side frame 140 contacts 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. doing. Further, in the fuel electrode side frame 140, a fuel gas supply communication hole 142 that communicates the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that communicates the fuel chamber 176 and the fuel gas discharge manifold 172. And are formed.

As shown in FIG. 6, the air electrode side current collector 134 is arranged in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of substantially square columnar current collector elements 135, 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 on the side facing the air electrode 114. 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 collector 134 in the power generation unit 102 has an upper end plate. It is in contact with 104. 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, the flat plate-shaped portion of the integral member that is orthogonal to the vertical direction (Z-axis direction) functions as the interconnector 150, and is formed so as to project from the flat plate-shaped portion toward the air electrode 114. The current collector element 135, which is a plurality of convex portions, functions as the air electrode side current collector 134. Further, the integral member of the air electrode side current collector 134 and the interconnector 150 may be covered with a conductive coat, and both are placed between the air electrode 114 and the air electrode side current collector 134. A conductive bonding layer to be bonded may be interposed.

As shown in FIG. 7, the fuel electrode side current collector 144 is arranged in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, a plurality of electrode facing portions 145, and a plurality of connecting portions 147 connecting the electrode facing portion 145 and the interconnector facing portion 146, and is conductive. It is made of material. The plurality of electrode facing portions 145 are arranged in a grid pattern along the X-axis direction and the Y-axis direction in the Z-axis direction. Further, in the present embodiment, the fuel electrode side current collector 144 is formed of a nickel foil (for example, a thickness of 10 to 200 μm). As shown in the partially enlarged view in FIG. 7, the fuel electrode side current collector 144 is manufactured by making a notch in a substantially rectangular nickel foil and processing the plurality of rectangular portions so as to bend them up. Each of the bent rectangular portions becomes the electrode facing portion 145, and the flat plate portion in which the hole 148 other than the bent portion is opened becomes the interconnector facing portion 146, and the electrode facing portion 145 and the interconnector facing portion 146 are formed. The connecting portion becomes the connecting portion 147. That is, the fuel electrode side current collector 144 composed of the interconnector facing portion 146, the electrode facing portion 145, and the connecting portion 147 is an integral member. In the partially enlarged view of FIG. 7, in order to show the manufacturing method of the fuel electrode side current collector 144, a state of a part of the rectangular portion before the bending raising process is completed is shown. The electrode facing portion 145 is in contact with the surface of the fuel pole 116 opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 facing the fuel pole 116. Are in contact. 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 interconnector facing portion 146 in the power generation unit 102 is the lower end plate. It is in contact with 106. Since the fuel pole side current collector 144 has such a configuration, the fuel pole 116 and the interconnector 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of an insulating material such as mica is arranged 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 follow. Good electrical connection with is maintained. The fuel electrode 116 corresponds to a specific electrode in the claims, and the fuel electrode side current collector 144 corresponds to a current collector in the claims. The detailed configuration of the fuel electrode side current collector 144 will be described later.

Since the fuel electrode side current collector 144 has the above configuration, the fuel chamber 176 has a row of electrode facing portions 145 arranged in the Y-axis direction and electrodes located adjacent to each other in the X-axis direction in the Z-axis direction. It is a space formed between the rows of the facing portions 145 and has a space extending substantially parallel to the Y-axis direction (hereinafter, referred to as “fuel gas flow path space 210”). The fuel gas flow path space 210 extends substantially parallel to the main flow direction of the fuel gas FG described later.

In the fuel electrode side current collector 144, the electrode facing portion 145 and the interconnector facing portion 146 are defined as follows. First, a first virtual extension surface in which the surface of the surface of the electrode facing portion 145 facing the spacer 149 is extended in a direction substantially orthogonal to the Z-axis direction (plane direction of the electrode facing portion 145) and an interconnector facing portion. A second virtual extension surface is defined in which the surface of the surface of 146 facing the spacer 149 is extended in a direction substantially orthogonal to the Z-axis direction (plane direction of the interconnector facing portion 146). At this time, the electrode facing portion 145 is a portion of the fuel pole side current collector 144 that exists between the first virtual extension surface and the fuel pole 116 in the Z-axis direction. The interconnector facing portion 146 is a portion of the fuel electrode side current collector 144 that exists between the second virtual extension surface and the interconnector 150 in the Z-axis direction. Further, the upper boundary B1 between the electrode facing portion 145 and the connecting portion 147 and the lower boundary B2 between the interconnector facing portion 146 and the connecting portion 147 are defined as follows. As shown in FIGS. 8 and 9, the upper boundary B1 intersects the first virtual extension surface and the surface of the fuel electrode side current collector 144 opposite to the side on which the spacer 149 is arranged. It is a line. The lower boundary B2 is a line of intersection where the second virtual extension surface intersects the surface of the fuel electrode side current collector 144 opposite to the side on which the spacer 149 is arranged. Further, the upper boundary B1 is a part of the outer edge of the electrode facing portion 145 in the Z-axis direction view. The lower boundary B2 is a part of the outer edge of the interconnector facing portion 146 in the Z-axis direction. In FIG. 9, both the upper boundary B1 and the lower boundary B2 are shown by dotted lines. In FIG. 8, the dotted line shown as the upper boundary B1 is a dotted line shown for convenience because it shows a part of the first virtual extension surface of the electrode facing portion 145. The dotted line shown as the lower boundary B2 is a dotted line shown for convenience in order to show a part of the second virtual extension surface of the interconnector facing portion 146.

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

When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, oxygen contained in the oxidant gas OG and hydrogen contained in the fuel gas FG in the single cell 110 are supplied. Power is generated by the 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 through the oxidant gas discharge communication hole 133 as shown in FIGS. 2, 4 and 6. Further, the fuel is passed through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162, and through the gas pipe (not shown) connected to the branch 29. It is discharged to the outside of the battery stack 100. Further, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the fuel gas discharge manifold 172 through the fuel gas discharge communication hole 143 as shown in FIGS. 3, 5 and 7. Further, the fuel cell stack 100 is passed through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the fuel gas discharge manifold 172, and through a gas pipe (not shown) connected to the branch 29. It is discharged to the outside of.

As shown in FIG. 6, the main flow direction of the oxidant gas OG in the air chamber 166 in each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment is generally from the positive X-axis side to the negative X-axis. The direction is toward the direction side. On the other hand, as shown in FIG. 7, the main flow direction of the fuel gas FG in the fuel chamber 176 in each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment is generally from the positive direction side of the Y axis to the negative direction of the Y axis. The direction is toward the side. That is, the fuel cell stack 100 of the present embodiment is a cross-flow type in which the main flow direction of the oxidant gas OG and the main flow direction of the fuel gas FG intersect.

A-3. Detailed configuration of the fuel electrode side current collector 144:
FIG. 8 is an XZ cross-sectional view showing a detailed configuration of the fuel electrode side current collector 144. FIG. 8 is an enlarged view of the X1 portion of FIG. 4, and a cross-sectional view of the position of VIII-VIII of FIG. 10 is shown. Further, FIG. 9 is a YZ cross-sectional view showing a detailed configuration of the fuel electrode side current collector 144. 9 is an enlarged view of the X2 portion of FIG. 5, and a cross-sectional view of the position of IX-IX in FIG. 10 is shown. Further, FIG. 10 is an XY sectional view showing a detailed configuration of the fuel electrode side current collector 144. 10 is an enlarged view of the X3 portion of FIG. 7, and a cross-sectional view of the position of XX in FIGS. 8 and 9 is shown.

As described above, the fuel electrode side current collector 144 has a plurality of electrode facing portions 145, and each electrode facing portion 145 is in contact with the surface of the fuel pole 116 (contact between the surfaces). In the present specification, the term "contact" refers to a state in which the member A and the member B are in direct contact with each other, and the member A and the member B are in contact with each other via another member C. It means that it also includes the state of being. For example, the “contact” between the electrode facing portion 145 and the fuel electrode 116 described above may be in a state where they are in direct contact with each other, or another member having conductivity (for example, Ni) between them. The paste) may be present.

In the present embodiment, the fuel electrode side current collector 144 is made of a material having no gas permeability. Here, the material having no gas permeability means a material that does not substantially permeate gas. As described above, the fuel electrode side current collector 144 in the present embodiment is formed of nickel foil.

Here, as shown in FIGS. 8 to 10, in the present embodiment, the surface of the electrode facing portion 145 on the spacer 149 side and the spacer 149 are arranged on each electrode facing portion 145 of the fuel electrode side current collector 144. A first defect space 40 (shown by a dotted line in FIG. 8) is formed so as to penetrate the surface opposite to the one on which the surface is located. In the present embodiment, the first defect space 40 is formed so as to penetrate the electrode facing portion 145 in the Z-axis direction (thickness direction). In the Z-axis direction view, the first defect space 40 faces the upper boundary B1 in the outer edge of the electrode facing portion 145 from approximately the center of the upper boundary B1 which is the boundary with the connecting portion 147 in the electrode facing portion 145. It extends in the direction of the outer edge on the side (in the present embodiment, the negative direction on the X-axis) and does not reach the outer edge on the side facing the upper boundary B1. In other words, in the present embodiment, the first defect space 40 in the Z-axis direction is directly communicated with the fuel chamber 176 at the upper boundary B1 of the electrode facing portion 145 and is directly connected to the upper side of the electrode facing portion 145. It is a defect (notch) that does not communicate with the fuel chamber 176 at the outer edge other than the boundary B1. That is, a first defect space 40 is formed in the electrode facing portion 145 so that the electrode facing portion 145 has a U shape in the Z-axis direction. Due to such a configuration, the first defective space 40 directly communicates with the fuel chamber 176.

Further, the first defective space 40 directly communicates with the fuel gas flow path space 210 extending substantially parallel to the main flow direction of the fuel gas in the fuel chamber 176. Further, the first defect space 40 is formed in a region including the center point P0 of the electrode facing portion 145 in the Z-axis direction view. When a region is defined by the outer edge of the electrode facing portion 145 in the Z-axis direction view, the center of gravity (face center) in the region can be set as the center point P0. Further, the fuel gas flow path space 210 corresponds to the gas flow path space in the claims.

Further, in the plane direction of the electrode facing portion 145 (the direction orthogonal to the Z-axis direction), the first defect space is along the direction in which the boundary line corresponding to the upper boundary B1 extends (in the present embodiment, the Y-axis direction). The length of 40 is preferably one-third or less of the length of the electrode facing portion 145 along the same direction. The depth of the first defect space 40 in the X-axis direction is preferably two-thirds or less of the length of the electrode facing portion 145 along the same direction. Further, in the Z-axis direction view, all the corner portions of the portion forming the first defect space 40 in the electrode facing portion 145 are R-shaped.

Further, as shown in FIGS. 8 to 10, in the present embodiment, the surface of the connecting portion 147 on the spacer 149 side and the spacer 149 are arranged on each connecting portion 147 of the fuel electrode side current collector 144. Is formed with a second defect space 50 (shown by a dotted line in FIG. 8) penetrating the surface on the opposite side. In the present embodiment, the second defect space 50 is formed so as to penetrate the connecting portion 147 in the X-axis direction (thickness direction). That is, the second defective space 50 is formed so as to face the fuel chamber 176. In the X-axis direction view, the second defect space 50 is the outer edge of the connecting portion 147 on the side facing the upper boundary B1 from approximately the center of the upper boundary B1 which is the boundary with the connecting portion 147 of the electrode facing portion 145. , Extends in the direction of the lower boundary B2 (in this embodiment, the Z-axis negative direction). Further, the second defective space 50 does not reach the lower boundary B2. In other words, in the present embodiment, the second defective space 50 in the X-axis direction is directly communicated with the first defective space 40 at the upper boundary B1 and is the interconnector facing portion in the connecting portion 147. It is separated from the lower boundary B2, which is the boundary with 146. Further, in the X-axis direction view, the second defect space 50 is a defect portion (notch) that does not reach the outer edge at the outer edge other than the upper boundary B1 in the connecting portion 147. That is, a second defect space 50 is formed in the connecting portion 147 so that the connecting portion 147 has a U shape in the X-axis direction. Due to such a configuration, the second defective space 50 directly communicates with the first defective space 40 and the fuel chamber 176. In other words, in the fuel electrode side current collector 144, the first defective space 40 is directly communicated with the second defective space 50.

In addition, the second defect space 50 is along the direction in which the boundary line corresponding to the upper boundary B1 extends (in the present embodiment, the Y-axis direction) in the surface direction of the connecting portion 147 (the direction orthogonal to the X-axis direction). Is preferably one-third or less of the length of the connecting portion 147 along the same direction. The depth of the second defect space 50 in the Z-axis direction is preferably not more than half the length of the connecting portion 147 along the same direction. Further, in the X-axis direction view, all the corner portions of the portion forming the second defect space 50 in the connecting portion 147 are R-shaped.

As shown in FIG. 8, in the present embodiment, the spacer 149 arranged between the electrode facing portion 145 and the interconnector facing portion 146 has an inner and upper boundary of the outer edge of the electrode facing portion 145 in the X-axis direction. It extends from the outer edge on the side facing B1 toward the upper boundary B1 and does not reach the surface of the connecting portion 147 facing the spacer 149. That is, as shown in FIG. 8, the end surface 60 of the spacer 149 on the connecting portion 147 side is separated from the connecting portion 147. As a result, a separation space 62 is formed between the end surface 60 of the spacer 149 and the connecting portion 147. The separation space 62 is directly connected to the first defective space 40 and the second defective space 50, and is directly connected to the fuel chamber 176.

The arrangement relationship between the fuel pole side current collector 144 and the air pole side current collector 134 in the power generation unit 102 will be described with reference to FIG. In the power generation unit 102 of the present embodiment, the current collector element 135 (air electrode side current collector 134) has an electrode whose width in the Y-axis direction of the current collector element 135 is relative to the fuel electrode side current collector 144. It is provided so as to be within the width range in the Y-axis direction of either of the two regions in the facing portion 145, that is, the region R1 or the region R2 (shown by the dotted line in FIG. 10). That is, the current collector element 135 (current collector 134 on the air electrode side) overlaps the portion other than the first defective space 40 in the Z-axis direction, and does not overlap the first defective space 40. Further, different current collector elements 135 (air electrode side current collector 134) are provided in the above two regions (regions R1 and R2). The regions R1 and R2 are two regions facing the electrode facing portion 145 of the fuel electrode side current collector 144 in the Y-axis direction with the first defect space 40 in between. Further, in FIG. 10, as the air pole side current collector 134 existing on the side facing the fuel pole side current collector 144 with the single cell 110 sandwiched, the X-axis direction is the longitudinal direction in the Z-axis direction. The outer edge of the current collector element 135 of the shape is shown by a dotted line. In FIG. 10, for convenience, only three current collector elements 135 out of the air electrode side current collector 134 included in the power generation unit 102 are shown, and the other current collector elements 135 are not shown. .. That is, another current collector element 135 is also arranged at a position facing the other fuel electrode side current collector 144 as described above.

A-4. Effect of this embodiment:
As described above, in each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment, the fuel electrode side current collector 144 comes into contact with the surface of the fuel pole 116 facing the fuel pole side current collector 144. The plurality of electrode facing portions 145, the plurality of interconnector facing portions 146 in contact with the surface of the interconnector 150 facing the fuel electrode side current collector 144, and the electrode facing portions 145 and the interconnector facing portion 146. It has a connecting portion 147 that connects the two. Further, each power generation unit 102 includes a spacer 149 that contacts the surface of the electrode facing portion 145 on the interconnector facing portion 146 side in the Z-axis direction. In each of such power generation units 102, a first defective space 40 facing the electrode facing portion 145 is formed in the electrode facing portion 145, and the first defective space 40 is an electrode in the fuel electrode 116. It communicates with the fuel chamber 176 facing the portion not facing the facing portion 145. As described above, in the power generation unit 102 of the present embodiment, the fuel is applied to the electrode facing portion 145 of the fuel pole side current collector 144 which is in contact with the surface of the fuel pole 116 facing the fuel pole side current collector 144. A first defect space 40 facing the pole 116 is formed. Therefore, in the power generation unit 102 of the present embodiment, the electrode facing portion of the fuel pole 116 is opposed to the electrode as compared with the configuration in which the first defect space 40 is not formed in the electrode facing portion 145 of the fuel pole side current collector 144. The water vapor generated in the region in contact with the portion 145 can be satisfactorily discharged to the fuel chamber 176 via the first defect space 40. Therefore, the retention of water vapor generated by the supply of the fuel gas FG to the fuel electrode 116 is suppressed, the inflow of the fuel gas FG into the fuel chamber 176 is facilitated, and the reaction in the single cell 110 is efficiently executed. can do. Further, in the power generation unit 102 of the present embodiment, the retention of water vapor in the region of the fuel electrode 116 in contact with the electrode facing portion 145 of the fuel electrode side current collector 144 is suppressed, and the increase in the partial pressure of water vapor is suppressed. can do. Therefore, in the power generation unit 102 of the present embodiment, it is possible to suppress the occurrence of microstructural changes in Ni due to the increase in the partial pressure of water vapor, and by extension, the performance deterioration of the single cell 110 can be suppressed.

Further, in the power generation unit 102 of the present embodiment, the first defective space 40 directly communicates with the fuel chamber 176. Therefore, the water vapor staying in the first defective space 40 can be directly discharged to the fuel chamber 176. Therefore, in the power generation unit 102 of the present embodiment, the reaction in the single cell 110 can be executed more efficiently, and the performance deterioration of the single cell 110 can be further suppressed.

Further, in the power generation unit 102 of the present embodiment, the first defective space 40 is directly communicated with the fuel chamber 176 on the upper boundary B1 side with the connecting portion 147 of the electrode facing portion 145, and the spacer 149. The end surface 60 on the connecting portion 147 side is separated from the connecting portion 147 on the electrode facing portion 145 side. The separation space 62 formed between the end surface 60 of the spacer 149 separated from the connecting portion 147 and the connecting portion 147 directly communicates with the first defective space 40 and directly communicates with the fuel chamber 176. There is. Therefore, the water vapor staying in the first defective space 40 can be discharged to the fuel chamber 176 via the separation space 62. As a result, it is possible to further suppress the retention of water vapor in the region of the fuel electrode 116 that is in contact with the electrode facing portion 145 of the fuel electrode side current collector 144. Further, since the separation space 62 communicates with the first defect space 40, the fuel gas FG easily diffuses into the first defect space 40. As a result, the reaction at the fuel electrode 116 facing the first defective space 40 can be promoted, and the water vapor staying in the first defective space 40 can be easily discharged to the fuel chamber 176. Therefore, in the power generation unit 102 of the present embodiment, the reaction in the single cell 110 can be executed more efficiently, and the performance deterioration of the single cell 110 can be further suppressed.

Further, in the power generation unit 102 of the present embodiment, a second defective space 50 facing the fuel chamber 176 is formed in the connecting portion 147, and the second defective space 50 is the first defective space 40. Directly communicate with. Therefore, the water vapor staying in the first defective space 40 can be effectively discharged to the fuel chamber 176 via the second defective space 50. Therefore, in the power generation unit 102 of the present embodiment, the reaction in the single cell 110 can be executed more efficiently, and the performance deterioration of the single cell 110 can be further suppressed.

Further, in the power generation unit 102 of the present embodiment, the second defective space 50 is separated from the second virtual extension surface of the interconnector facing portion 146. Therefore, the water vapor staying in the first defective space 40 can be effectively discharged to the fuel chamber 176, and the strength of the connecting portion 147 of the fuel electrode side current collector 144 can be secured. Therefore, in the power generation unit 102 of the present embodiment, the reaction in the single cell 110 can be executed more efficiently, and the strength at the connecting portion 147 of the fuel electrode side current collector 144 can be secured.

Further, in the power generation unit 102 of the present embodiment, the first defective space 40 is formed in a region including the center point P0 of the electrode facing portion 145 in the Z-axis direction view. The water vapor generated by the reaction at the fuel electrode 116 is difficult to be discharged to the fuel chamber 176 and tends to stay in the region including the center point P0 of the electrode facing portion 145, which is the surface in contact with the fuel electrode 116. According to the power generation unit 102 of the present embodiment, by forming the first defect space 40 in the region including the center point P0 of the electrode facing portion 145, the discharge of water vapor to the fuel chamber 176 is facilitated. It is possible to reduce the retention of water vapor between the fuel electrode 116 and the electrode facing portion 145. Therefore, in the power generation unit 102 of the present embodiment, the reaction in the single cell 110 can be executed more efficiently, and the performance deterioration of the single cell 110 can be further suppressed.

Further, in the power generation unit 102 of the present embodiment, the first defective space 40 directly communicates with the fuel gas flow path space 210 extending substantially parallel to the main flow direction of the fuel gas FG in the fuel chamber 176. In this way, since the first defective space 40 is directly communicated with the fuel gas flow path space 210 in the fuel chamber 176, the water vapor staying in the first defective space 40 is discharged to the fuel chamber 176 more efficiently. can do. Therefore, in the power generation unit 102 of the present embodiment, the reaction in the single cell 110 can be executed more efficiently, and the performance deterioration of the single cell 110 can be further suppressed.

Further, another air pole side current collector 134 facing the fuel pole side current collector 144 across the single cell 110 sandwiches the first defective space 40 in the electrode facing portion 145 in the Z-axis direction. When the two regions (regions R1 and R2) facing each other in the axial direction do not overlap, stress is concentrated near the edge of the air electrode side current collector 134 in the single cell 110, which may cause cell cracking or the like. On the other hand, in the power generation unit 102 of the present embodiment, at least a part of the other air pole side current collectors 134 facing the fuel pole side current collector 144 with the single cell 110 sandwiched is opposed to the electrodes in the Z-axis direction. It is arranged so as to overlap at least a part of the above two regions (regions R1 and R2) in the portion 145. Therefore, in the power generation unit 102 of the present embodiment, stress concentration occurs in the single cell 110 when assembling a plurality of single cells 110 to form the fuel cell stack 100 or during the operation of the fuel cell stack 100, resulting in cells. It reduces the occurrence of performance degradation due to cracking.

Further, in the power generation unit 102 of the present embodiment, the electrode facing portion 145 is formed with a first defect space 40 so that the electrode facing portion 145 has a U shape in the Z-axis direction, and the Z axis is formed. In the directional view, the corner portion of the portion forming the first defect space 40 in the electrode facing portion 145 has an R shape. By forming the corner portion into an R shape, it is possible to reduce the occurrence of stress concentration at the corner portion when processing the fuel electrode side current collector 144 or during the operation of the fuel cell stack 100, and by extension, the stress. It is possible to reduce the occurrence of cracks starting from the corners where they are concentrated.

B. 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. For example, the techniques disclosed herein can also be applied to known structures of fuel cells such as cylindrical and cylindrical flat plates.

As shown in FIG. 11, in the above embodiment, the first defect space 40 (shown by the dotted line in FIG. 11A) is the inner edge of the electrode facing portion 145 in the Z-axis direction. , Extends from approximately the center of the upper boundary B1 with the connecting portion 147 toward the outer edge of the side facing the upper boundary B1 (in the negative direction of the X axis), and reaches the outer edge of the side facing the upper boundary B1. It may be a mode. In other words, the first defect space 40 in the Z-axis direction is directly connected to the fuel chamber 176 at the upper boundary B1 at the electrode facing portion 145 and is opposed to the upper boundary B1 at the electrode facing portion 145. The outer edge of the fuel chamber may also be a defect (notch) that directly communicates with the fuel chamber 176. That is, as shown in FIG. 11B, an I-shaped first defect space 40 is formed in the electrode facing portion 145 in the Z-axis direction. Due to such a configuration, the first defect space 40 communicates with the fuel chamber 176 at both the upper boundary B1 and the outer edge of the side facing the upper boundary B1 in the outer edge of the electrode facing portion 145. It will be. Further, the connecting portion 147 may be formed with a second defective space 50 (shown by a dotted line in FIG. 11A), similarly to the connecting portion 147 in the above embodiment. In such an embodiment, the spacer 149 extends in the direction of the upper boundary B1 from the outer edge of the outer edge of the electrode facing portion 145 facing the upper boundary B1 in the X-axis direction, and is connected to the connecting portion 147. It may reach the surface facing the spacer 149 in the above. In this case, the end surface 60 of the spacer 149 on the connecting portion 147 side is not separated from the connecting portion 147. That is, the separation space 62 may not be formed.

As shown in FIG. 12, in the above embodiment, the fuel electrode side current collector 144 may have only the first defective space 40 (shown by the dotted line in FIG. 12A). That is, the second defective space 50 may not be formed in the connecting portion 147 of the fuel electrode side current collector 144. In such an embodiment, the spacer 149 is mounted on the spacer 149 on the side facing the electrode facing portion 145 in the Z-axis direction from the outer edge of the outer edge of the electrode facing portion 145 facing the upper boundary B1 in the X-axis direction. It extends toward the upper boundary B1 and does not reach the surface of the connecting portion 147 facing the spacer 149, while the spacer 149 facing the interconnector in the Z-axis direction 146 side is in the X-axis direction. In the outer edge of the electrode facing portion 145, the outer edge on the side facing the upper boundary B1 may extend toward the upper boundary B1 and reach the surface of the connecting portion 147 facing the spacer 149. In this case, of the end faces 60 on the connecting portion 147 side of the spacer 149, the end face 60a on the electrode facing portion 145 side is separated from the connecting portion 147, and the end face 60b on the interconnector facing portion 146 side is separated from the connecting portion 147. It means that they are not separated. That is, the separation space 62 may be formed only between the end surface 60a of the spacer 149 and the connecting portion 147.

As shown in FIG. 13A, in the above embodiment, the first defect space 40 is the upper boundary with the connecting portion 147 in the outer edge of the electrode facing portion 145 in the Z-axis direction view in the Z-axis direction view. It may extend from substantially the center of the outer edge on the side facing B1 toward the upper boundary B1 (positive direction on the X-axis) and may not reach the upper boundary B1. In other words, the first defect space 40 in the Z-axis direction is directly communicated with the fuel chamber 176 at the outer edge of the electrode facing portion 145 facing the upper boundary B1 and is in the electrode facing portion 145. It may be a defect (notch) that does not communicate with the fuel chamber 176 at an outer edge other than the outer edge on the side facing the upper boundary B1. That is, a first defect space 40 may be formed in the electrode facing portion 145 so that the electrode facing portion 145 has a U shape in the Z-axis direction.

As shown in FIG. 13B, in the above embodiment, the first defect space 40 is the upper boundary with the connecting portion 147 in the outer edge of the electrode facing portion 145 in the Z-axis direction view in the Z-axis direction view. A rectangular portion extending from substantially the center of B1 toward the outer edge direction (X-axis negative direction) on the side facing the upper boundary B1 and a center point P0 of the electrode facing portion 145, and the Y-axis of the rectangular portion It may be a mode in which a substantially circular circular portion having a diameter wider than the width in the direction is connected. In other words, the first defect space 40 in the Z-axis direction is directly communicated with the fuel chamber 176 at the upper boundary B1 at the electrode facing portion 145, and is an outer edge other than the upper boundary B1 at the electrode facing portion 145. It may be a defective portion (notch) that does not communicate with the fuel chamber 176. That is, the electrode facing portion 145 is formed with the first defect space 40 having a key hole shape in the Z-axis direction. In FIG. 13B, the shape of the tip portion of the first defect space 40 is substantially circular, but the shape is not limited to the substantially circular shape, and may be a substantially rectangular shape or another shape.

As shown in FIG. 14A, in the above embodiment, the first defect space 40 is the upper boundary with the connecting portion 147 in the outer edge of the electrode facing portion 145 in the Z-axis direction view in the Z-axis direction view. The upper boundary B1 is from the first portion extending from the substantially center of B1 toward the outer edge direction (X-axis negative direction) on the side facing the upper boundary B1 and the outer edge on the side facing the upper boundary B1. It is composed of a second portion extending in the direction of (X-axis positive direction), and the first portion may not reach the second portion at the center point P0 of the electrode facing portion 145. In other words, the first defect space 40 in the Z-axis direction is directly connected to the fuel chamber 176 at the upper boundary B1 at the electrode facing portion 145 and the outer edge facing the upper boundary B1 at the electrode facing portion 145. A defect (notch) that communicates and does not directly communicate with the fuel chamber 176 at an outer edge other than the upper boundary B1 at the electrode facing portion 145 and the outer edge facing the upper boundary B1 at the electrode facing portion 145. There may be. That is, the electrode facing portion 145 is formed with the first defect space 40 so that the electrode facing portion 145 has an H shape in the Z-axis direction.

As shown in FIG. 14B, in the above embodiment, the first defect space 40 is the upper boundary with the connecting portion 147 in the outer edge of the electrode facing portion 145 in the Z-axis direction view in the Z-axis direction view. It may be a mode including two portions extending from B1 toward the outer edge on the side facing the upper boundary B1 (negative direction on the X-axis) and not reaching the outer edge on the side facing the upper boundary B1. In other words, the first defect space 40 in the Z-axis direction is directly communicated with the fuel chamber 176 at two points of the upper boundary B1 in the electrode facing portion 145, and is directly connected to the upper boundary B1 in the electrode facing portion 145. The outer edge on the side facing the fuel chamber may be a defect (notch) that does not communicate with the fuel chamber 176. That is, the electrode facing portion 145 is formed with the first defect space 40 so that the electrode facing portion 145 has an E shape in the Z-axis direction.

The combination of the fuel electrode side current collector 144 and the spacer 149 is not limited to the combination described in the above embodiment and the modified example, and the fuel electrode side current collector 144 and the spacer described in the above embodiment and the modified example are not limited to the combination. It can be freely combined with 149.

Further, in the power generation unit 102 of the above embodiment, the first defect space 40 is a through hole penetrating the electrode facing portion 145 in the thickness direction, and the second defect space 50 penetrates the connecting portion 147 in the thickness direction. It is a hole, but it is not limited to this. That is, the first defect space 40 may be a bottomed hole that opens on the surface of the surface of the electrode facing portion 145 facing the fuel electrode 116 and does not penetrate the electrode facing portion 145 in the thickness direction. .. Similarly, the second defect space 50 may be a bottomed hole that opens to the surface of the surface of the connecting portion 147 on the side facing the fuel chamber 176 and does not penetrate the connecting portion 147 in the thickness direction. Further, the first defective space 40 and the second defective space 50 may both be through holes, both may be bottomed holes, or may be a combination of through holes and bottomed holes. .. Further, the structure may be such that a part of the first defective space 40 penetrates and the other part does not penetrate. The same applies to the second defective space 50.

In the power generation unit 102 of the present embodiment, the air pole side current collector 134 facing the fuel pole side current collector 144 with the single cell 110 sandwiched is the region R1 in the electrode facing portion 145 of the fuel pole side current collector 144. It is decided that the equipment is provided so as to be within the width of R2, but the present invention is not limited to this. For example, at least a part of the air electrode side current collector 134 overlaps at least a part of the regions R1 and R2 facing the Y-axis direction with the first defect space 40 in the electrode facing portion 145 in the Z-axis direction view. The configuration may be arranged so as to.

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 cross-flow type power generation unit 102 is exemplified as the electrochemical reaction unit, but the present invention is not limited to this, and the main flow direction of the oxidant gas and the main flow direction of the fuel gas are substantially opposite directions ( It may be a counterflow type configuration in which the directions are opposite to each other, 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.

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 single cell, which is a constituent unit of a solid oxide fuel cell (SOEC) that generates hydrogen by utilizing it, and an electrolytic cell stack including a plurality of electrolytic single cells. The configuration of the electrolytic cell stack is not described in detail here because it is known as described in, for example, International Publication No. 2012/165409, but is generally the same as the fuel cell stack 100 in the above-described embodiment. It is the composition of. 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 to the fuel chamber 176. As a result, an electrolysis reaction of water occurs in each electrolytic cell, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out of the electrolytic cell stack through the communication hole 108.

Here, during the operation of the SOEC, water vapor as a gas supplied to the fuel electrode 116 side is subjected to a reaction in the electrolytic single cell while advancing in the gas flow direction, so that it is upstream of the fuel electrode 116 in the gas flow direction. The partial pressure of water vapor increases in the region on the side. Therefore, even in SOEC, there is a problem that the microstructural change of Ni contained in the fuel electrode 116 is promoted by increasing the partial pressure of water vapor in a specific region of the fuel electrode 116, and the performance of the electrolytic single cell is likely to deteriorate. is there. Therefore, also in the fuel electrode side current collector 144 of the electrolytic single cell, the first defective space 40 is formed in the electrode facing portion 145, and the first defective space 40 communicates with the fuel chamber 176. If it is adopted, it is possible to suppress the occurrence of microstructural changes in Ni due to an increase in the partial pressure of water vapor, and by extension, it is possible to suppress deterioration in the performance of the single cell 110.

Further, the configuration of the fuel electrode 116 (relationship of Ni content, etc.) described in the above embodiment includes all the single cells 110 (or electrolytic single cells) included in the fuel cell stack 100 (or the electrolytic cell stack, the same applies hereinafter). It may be adopted in the single cell 110 of only a part included in the fuel cell stack 100.

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 40: First defective space 50: Second defective space 60, 60a, 60b: End face 62: Separation space 100: Fuel cell stack 102: Fuel cell power generation unit (power generation unit) 104, 106: End plate 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air electrode (cathode) 116: Fuel electrode (anode) 120: Separator 121: Hole 124: Joint 130: Air pole side frame 131: Hole 132: Oxidizing agent gas supply communication hole 133: Oxidizing agent gas discharge communication hole 134: Air pole side current collector 135: Current collector element 140: Fuel pole side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel electrode side current collector 145: Electrode facing part 146: Interconnector facing part 147: Connecting part 148: Hole 149: Spacer 150: Interconnector 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 210: Fuel gas flow path space

Claims (8)

An electrochemical reaction single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer.
A conductive interconnector arranged on one of the fuel electrode and the air electrode on the specific electrode side with respect to the electrochemical reaction single cell,
A conductive current collector that is arranged between the specific electrode and the interconnector in the first direction and electrically connects the specific electrode and the interconnector, and is the said in the specific electrode. A plurality of electrode facing portions in contact with the surface facing the current collector, a plurality of interconnector facing portions in contact with the surface of the interconnector facing the current collector, the electrode facing portion and the above. A current collector having a connecting portion that connects the interconnector facing portions, and
In an electrochemical reaction unit comprising a spacer in contact with the surface of the electrode facing portion on the side facing the interconnector in the first direction.
A first defect space facing the specific electrode is formed in at least one electrode facing portion.
Said first defect space in the boundary side of the connecting portion in the electrode facing portion, it communicates directly with the gas chamber facing the not opposed to the electrode facing portions of said particular electrode,
The end surface of the spacer on the connecting portion side is separated from the connecting portion on the electrode facing portion side, and a separation space formed between the end surface of the spacer separated from the connecting portion and the connecting portion. Directly communicates with the first defective space and directly communicates with the gas chamber.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 1,
A second defect space facing the gas chamber is formed in the connecting portion.
The second defective space directly communicates with the first defective space.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 2,
The second defect space is separated from a virtual extension surface in which the surface of the surface of the interconnector facing portion facing the spacer is extended in a direction substantially orthogonal to the first direction.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to any one of claims 1 to 3.
The first defect space is formed in a region including the center point of the electrode facing portion in the first directional view.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 1,
The first defect space directly communicates with a gas flow path space extending substantially parallel to the main flow direction of gas in the gas chamber.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to any one of claims 1 to 5.
At least a part of the other current collectors facing the current collector with the electrochemical reaction single cell sandwiched sandwiching the first defect space in the electrode facing portion in the first directional view is predetermined. Arranged so as to overlap at least a part of two regions facing each other in the direction of
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to any one of claims 1 to 6.
The first defect space is formed in the electrode facing portion so that the electrode facing portion has a U shape in the first directional view.
In the first directional view, at least one corner portion of the portion of the electrode facing portion forming the first defect space has an R shape.
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.
At least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to any one of claims 1 to 7 .
It is characterized by an electrochemical reaction cell stack.

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