JP6959039B2 - Method for manufacturing electrochemical reaction unit, electrochemical reaction cell stack, and electrochemical reaction unit - 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 power 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 two electrodes (air electrode and fuel electrode) facing each other in a predetermined direction (hereinafter, referred to as "first direction") with the electrolyte layer interposed therebetween.

Further, the power generation unit includes a conductive current collector having a plurality of convex portions facing the surface of one of the air electrode and the fuel electrode (hereinafter, referred to as “specific electrode”). The current collector is a member for extracting electric power generated by a power generation reaction in a single cell. The power generation unit is further provided for each of the plurality of convex portions of the current collector, and includes a conductive bonding material for bonding the surface of the convex portion and the surface of the specific electrode (see, for example, Patent Document 1). Each convex portion of the current collector and the specific electrode are bonded to each other and electrically connected to each other via a bonding material.

Japanese Unexamined Patent Publication No. 2015-122225

In the above-mentioned conventional configuration, if the conductive path between the convex portion of the current collector and the bonding material is not sufficiently secured, the contact resistance may increase and the performance of the reaction unit may deteriorate. Further, in the above-mentioned conventional configuration, if the region covered by the bonding material on the surface of the specific electrode is large, the gas diffusion resistance may increase and the performance of the reaction unit may deteriorate. In the above-mentioned conventional configuration, there is room for improvement in terms of both suppressing the performance deterioration of the reaction unit due to the increase in contact resistance and suppressing the performance deterioration of the reaction unit due to the increase in gas diffusion resistance.

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. 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 techniques disclosed herein 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. A conductive current collector having a plurality of convex portions facing the surface of a specific electrode having one of the air electrode and the fuel electrode, and the surface of the convex portion is each on the surface of the convex portion. A side surface portion composed of each point having an angle formed by a virtual tangent plane at a point and the surface of the specific electrode of 45 degrees or more, and a side surface portion surrounded by the side surface portion and having an angle of less than 45 degrees. A conductive bonding material provided for each of the current collector and the plurality of convex portions, including a bottom surface portion composed of points, and for joining the surface of the convex portion and the surface of the specific electrode. With respect to the bonding material provided for at least one of the convex portions in the electrochemical reaction unit comprising, (a) the bonding material is the said in the bottom surface portion of the convex portion and the side surface portion of the convex portion. In the second direction, which is in contact with at least a part of the region adjacent to the bottom surface portion and (b) orthogonal to the first direction, the maximum width of the joint material is the same as that of the joint material in the convex portion. It is larger than the maximum width of the contacting portion, and (c) the contact angle between the bonding material and the surface of the specific electrode is an blunt angle. According to the present electrochemical reaction unit, the bonding material is in contact with at least a part of the side surface portion of the convex portion in addition to the bottom surface portion of the convex portion of the current collector (requirement (a) above). Moreover, since the maximum width of the bonding material is larger than the maximum width of the convex portion of the current collector (requirement (b) above), it is necessary to sufficiently secure a conductive path between the convex portion of the current collector and the bonding material. As a result, it is possible to suppress the deterioration of the performance of the electrochemical reaction unit due to the increase in contact resistance. Further, according to the present electrochemical reaction unit, since the contact angle between the bonding material and the surface of the specific electrode is an obtuse angle (the above requirement (c)), a configuration satisfying the above requirements (a) and (b) is adopted. However, the region covered by the bonding material on the surface of the specific electrode can be reduced, and as a result, the deterioration of the performance of the electrochemical reaction unit due to the increase in gas diffusion resistance can be suppressed. Therefore, according to this electrochemical reaction unit, it is effective to suppress the performance deterioration of the electrochemical reaction unit due to the increase in contact resistance and the performance deterioration of the electrochemical reaction unit due to the increase in gas diffusion resistance. Can be compatible with.

(2) In the electrochemical reaction unit, the contact angle between the bonding material and the surface of the specific electrode may be 110 degrees or more and 160 degrees or less. According to this electrochemical reaction unit, it is possible to achieve a good balance between securing a conductive path between the convex portion of the current collector and the bonding material and reducing the area of the area covered by the bonding material on the surface of the specific electrode. Therefore, the deterioration of the performance of the electrochemical reaction unit can be effectively suppressed.

(3) In the electrochemical reaction unit, in the first direction, from the surface of the specific electrode to the position of the maximum width of the bonding material with respect to the height t2 of the gas chamber facing the surface of the specific electrode. The ratio of the distance t1 (t1 / t2) may be 0.02 or more. In this electrochemical reaction unit, since the above ratio (t1 / t2) is as large as 0.02 or more, the portion having the maximum width in the bonding material is separated from the surface of the specific electrode to some extent. It is possible to suppress the obstruction of the gas flow near the surface of the specific electrode, and it is possible to effectively suppress the deterioration of the performance of the electrochemical reaction unit due to the increase in the gas diffusion resistance.

(4) In the electrochemical reaction unit, the electrochemical reaction single cell may be configured to be a fuel cell single cell. According to this electrochemical reaction unit, it is effective to suppress the decrease in power generation performance of the electrochemical reaction unit due to the increase in contact resistance and the decrease in power generation performance of the electrochemical reaction unit due to the increase in gas diffusion resistance. Can be compatible with.

(5) The method for producing an electrochemical reaction unit disclosed in the present specification is an electrochemical reaction unit including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween. A conductive current collector having a cell and a plurality of convex portions facing the surface of a specific electrode having one of the air electrode and the fuel electrode, and the surface of the convex portion is the surface of the convex portion. The side surface portion formed by each point where the angle formed by the virtual tangent plane at each of the above points and the surface of the specific electrode is 45 degrees or more, and the side surface portion surrounded by the side surface portion, the formed angle is less than 45 degrees. A conductive bottom surface portion composed of each of the above points, which is provided for each of the current collector and the plurality of convex portions, and joins the surface of the convex portion and the surface of the specific electrode. In the method for producing an electrochemical reaction unit comprising a bonding material, a first step of applying a paste for the bonding material to at least the bottom surface portion of the surface of each of the convex portions of the current collector. After the first step, the paste is identified by relatively moving the current collector and the electrochemical reaction single cell in the first direction without performing a process of raising the temperature of the paste. After the second step of forming the specific state in contact with the surface of the electrode, the third step of maintaining the specific state for a predetermined time after the second step, and the third step, the said The present invention includes a fourth step of forming the bonding material by performing a process of raising the temperature of the paste. According to the method for producing the present electrochemical reaction unit, the process of raising the temperature of the paste is not performed in the second step, so that the viscosity of the paste changes from the time of application in the first step (decrease in viscosity due to heating). (Increase in viscosity due to drying) is suppressed. By suppressing the decrease in the viscosity of the paste from the time of application, an unintended change in the shape of the paste (excessive spread in the direction orthogonal to the first direction (plane direction)) is suppressed. Further, by suppressing the increase in the viscosity of the paste from the time of application, the occurrence of poor contact between the paste and the surface of the convex portion (particularly, the side surface portion) is suppressed. Further, according to the method for producing the electrochemical reaction unit, after the second step, a third step of maintaining the specific state in which the paste is in contact with the surface of the specific electrode is performed for a predetermined time. In the portion near the surface of the specific electrode, the solvent content in the paste permeates into the relatively porous specific electrode to further increase the viscosity, and as a result, the paste spreads effectively in the plane direction. It is suppressed. On the other hand, in the portion of the paste near the convex portion of the current collector, the viscosity is generally maintained, so that the paste spreads satisfactorily from the bottom surface portion to the side surface portion of the convex portion of the current collector. After that, by performing the fourth step of forming the bonding material by raising the temperature of the paste, the spread in the plane direction is suppressed in the vicinity of the surface of the specific electrode, and in the vicinity of the convex portion of the current collector. A joining material having a shape extending from the bottom surface portion of the convex portion to the side surface portion is formed. That is, the formed joining material satisfies the above-mentioned requirements (a) to (c). As described above, according to the method for producing the present electrochemical reaction unit, it is possible to produce the electrochemical reaction unit having the bonding material satisfying the above-mentioned requirements (a) to (c). Therefore, according to the method for producing this electrochemical reaction unit, it is possible to effectively both suppress the performance deterioration due to the increase in contact resistance and the performance deterioration due to the increase in gas diffusion resistance. Chemical reaction units can be produced.

(6) The electrochemical reaction cell stack disclosed in the present specification is an electrochemical reaction cell stack including a plurality of electrochemical reaction units arranged side by side in the first direction, wherein the plurality of electrochemical reaction units are used. At least one is the electrochemical reaction unit. According to this electrochemical reaction cell stack, it is effective to suppress the performance deterioration of the electrochemical reaction unit due to the increase in contact resistance and the performance deterioration of the electrochemical reaction unit due to the increase in gas diffusion resistance. It can be compatible.

(7) In the method for producing an electrochemical reaction unit, the first step may be a step of applying the paste of 60 Pa · s or more and 150 Pa · s or less. According to the method for producing this electrochemical reaction unit, by setting the viscosity of the paste applied in the first step to 60 Pa · s or more, an unintended change in the shape of the paste (excessive in the plane direction) in the subsequent steps. Can be effectively suppressed. Further, by setting the viscosity of the paste applied in the first step to 150 Pa · s or less, the paste can be smoothly applied to the convex portion of the current collector.

(8) In the method for producing an electrochemical reaction unit, the first step may be a step of applying the paste in a thickness of 20 μm or more and 50 μm or less. According to the method for producing the electrochemical reaction unit, the thickness of the paste applied in the first step is 20 μm or more, so that the paste is in contact with the surface of the specific electrode in the second step. At that time, the dimensional variation of each member can be absorbed by the paste, and reliable bonding and electrical connection by the bonding material can be realized. Further, by setting the thickness of the paste applied in the first step to 50 μm or less, it is possible to prevent the width of the bonding material formed from the paste in the plane direction from becoming excessive and increasing the gas diffusion resistance. Can be done.

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 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. 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. It is explanatory drawing which shows the structure of the power generation unit 102X in the 1st comparative example. It is explanatory drawing which shows the structure of the power generation unit 102Y in the 2nd comparative example. It is a flowchart which shows an example of the manufacturing method of the fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the outline of the manufacturing method of the power generation unit 102 in the manufacturing method of the fuel cell stack 100 in this embodiment.

A. Embodiment:
A-1. composition:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 in the embodiment, and FIG. 2 is an XZ cross section of the fuel cell stack 100 at the position II-II in FIG. 1 (and FIGS. 6 and 7 described later). It is explanatory drawing which shows the structure, and FIG. 3 is the explanatory view which shows the YZ cross section structure of the fuel cell stack 100 at the position of 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 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.

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 Z 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, the position is near the midpoint of one side (the side on the positive side of the X axis among the two sides parallel to the Y axis) on the outer circumference of the fuel cell stack 100 in the Z direction. In the space formed by the 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 generated for each power generation. It functions as an oxidizer gas introduction manifold 161 that is a gas flow path supplied to the unit 102, and is the midpoint of the opposite side (the side on the negative direction of the X axis of the two sides parallel to the Y axis). The space formed by the bolt 22 (bolt 22B) located in the vicinity and the communication hole 108 through which the bolt 22B is inserted provides the oxidant off-gas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidizer gas discharge manifold 162 that discharges to the outside of the fuel cell stack 100. In this embodiment, for example, air is used as the oxidant gas OG.

Further, as shown in FIGS. 1 and 3, the vicinity of the midpoint of one side (the side on the positive direction of the Y axis among the two sides parallel to the X axis) on the outer circumference of the fuel cell stack 100 around the Z 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 above and the communication hole 108 through which the bolt 22D is inserted, and the fuel gas FG is generated by each power generation. A bolt 22 that functions as a fuel gas introduction manifold 171 to be supplied to the unit 102 and is located near the midpoint of the opposite side (the side on the negative side of the Y axis of the two sides parallel to the X axis). The space formed by (bolt 22E) and the communication hole 108 through which the bolt 22E is inserted sends the fuel off-gas FOG, which is the gas discharged from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100. It functions as a fuel gas discharge manifold 172 to be discharged. 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 cylindrical main body 28 and a hollow cylindrical 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 located above the power generation unit 102 located at the top, and the other end plate 106 is located below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are sandwiched by a pair of end plates 104 and 106 in a pressed state. 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 the XZ cross-sectional configuration of the 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. In the upper part of FIG. 5, the YZ cross-sectional structure of a part of the power generation unit 102 is enlarged and shown. Further, FIG. 6 is an explanatory view showing the XY cross-sectional configuration of the power generation unit 102 at the position of VI-VI in FIG. 4, and FIG. 7 is an explanatory view showing the XY cross-sectional configuration of the power generation unit 102 at the position of VII-VII in FIG. It is explanatory drawing which shows.

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 in the peripheral portions of the separator 120, the air pole side frame 130, the fuel pole side frame 140, and the interconnector 150 in the Z direction.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic 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 has an electrolyte layer 112, a fuel electrode (anode) 116 arranged on one side (lower side) of the electrolyte layer 112 in the vertical direction (first direction), and the other side of the electrolyte layer 112 in the vertical direction. It includes an air electrode (cathode) 114 arranged on the (upper side) and an intermediate layer 180 arranged between the electrolyte layer 112 and the air electrode 114. The single cell 110 of the present embodiment is a fuel pole support type single cell that supports other layers (electrolyte layer 112, air pole 114, intermediate layer 180) constituting the single cell 110 with the fuel pole 116.

The electrolyte layer 112 is a flat plate-shaped member that is substantially rectangular in the Z 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 (gadrinium-doped ceria), and perovskite-type oxide. There is. That is, 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 air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 in the Z 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 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 intermediate layer 180 is a substantially rectangular flat plate-shaped member, and is formed so as to include GDC (gadolinium-doped ceria). In the intermediate layer 180, an element (for example, Sr) diffused from the air electrode 114 reacts with an element (for example, Zr) contained in the electrolyte layer 112 to _{generate a highly resistant substance (for example, SrZrO 3} ). Suppress.

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 formed of, for example, metal. 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 FIGS. 4 to 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. ing. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. 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. .. 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 FIGS. 4, 5 and 7, the fuel pole 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. 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. 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 FIGS. 4, 5 and 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, an electrode facing portion 145, and a connecting portion 147 connecting the electrode facing portion 145 and the interconnector facing portion 146. For example, nickel or nickel alloy. , Stainless steel, etc. 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, for example, mica is arranged between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel pole 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 pole 116 and the interconnector 150 (or the end plate 106) via the fuel pole side current collector 144 follow. Good electrical connection with is maintained.

As shown in FIGS. 4 to 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 to each other.

The space between the two adjacent current collector elements 135 constituting the air electrode side current collector 134 functions as a gas flow path through which the oxidant gas OG flows. As shown in FIG. 6, in the present embodiment, the current collector elements 135 are arranged so as to be aligned in the X-axis direction and the Y-axis direction in a direction in which the axial direction (longitudinal direction) substantially coincides with the X-axis direction. ing. Therefore, the gas flow path through which the oxidant gas OG flows has a shape extending in a grid pattern in the X-axis direction and the Y-axis direction in the Z-axis direction.

Further, in the present embodiment, the air electrode side current collector 134 (current collector element 135) and the interconnector 150 are formed as an integral member. That is, the flat plate-shaped portion of the integrated 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 plurality of current collector elements 135 function as the air electrode side current collector 134.

Further, as shown in FIGS. 4 and 5, the surface of the air electrode side current collector 134 (current collector element 135) is covered with a conductive coat 136. The coat 136 is formed of, for example, a spinel-type oxide (for example, Mn _1.5 Co _1.5 O ₄ or _{Mn Co 2} O ₄ , ZnCo ₂ O ₄ , ZnMn ₂ O ₄ , ZnMn CoO ₄ , _{Cumn 2} O ₄ ). ing. The formation of the coat 136 on the surface of the air electrode side current collector 134 is performed by a well-known method such as spray coating, inkjet printing, spin coating, dip coating, plating, sputtering, and thermal spraying. As described above, in the present embodiment, the air electrode side current collector 134 (current collector element 135) and the interconnector 150 are formed as an integral member, so that the air electrode side current collector is actually collected. Of the surface of the electric body 134 (current collector element 135), the boundary surface with the interconnector 150 is not covered by the coat 136, while at least the gas flow path through which the oxidant gas OG flows in the surface of the interconnector 150. The surface facing the air (for example, the surface of the interconnector 150 on the air electrode 114 side) is covered with a coat 136. Further, a film of chromium oxide may be formed by heat treatment on the air electrode side current collector 134 or the like, but in that case, the coat 136 is not the film, but the air electrode side current collector 134 on which the film is formed. It is a layer formed so as to cover. In the following description, unless otherwise specified, the air electrode side current collector 134 (current collector element 135) means "air electrode side current collector 134 covered with coat 136 (current collector element 135)". Note that in FIG. 6, the coating 136 is omitted.

Further, as shown in FIGS. 4 and 5, the air electrode 114 and the air electrode side current collector 134 (current collector element 135) are joined by a conductive bonding material 138. The bonding material 138 includes, for example, spinel-type oxides (for example, Mn _1.5 Co _1.5 O ₄ and _{Mn Co 2} O ₄ , ZnCo ₂ O ₄ , ZnMn ₂ O ₄ , ZnMn CoO ₄ , _{Cumn 2} O ₄ ) and perovskite. It is formed of a type oxide (eg, LSCF). In the present embodiment, the joining material 138 that joins one current collector element 135 and the air pole 114 and the joining material 138 that joins the other current collector element 135 and the air pole 114 are independent of each other. There is. The air electrode 114 and the air electrode side current collector 134 are electrically connected by the joining material 138. Earlier, it was explained that the air electrode side current collector 134 is in contact with the surface of the air electrode 114, but to be precise, a bonding material 138 is provided between the air electrode side current collector 134 and the air electrode 114. It is intervening. The configuration of the joining material 138 will be described in more detail later.

As shown in FIG. 5, in the above-described configuration, the integral member of the interconnector 150 and the air electrode side current collector 134 (current collector element 135) and the coat 136 are combined into one member (hereinafter, “current collector”). 190 ”), a plurality of parts (hereinafter referred to as“ convex portion 192 ”) of the current collector 190 composed of the current collector element 135 covered with the coat 136 are covered with the coat 136. It protrudes toward the air electrode 114 from the portion composed of the broken interconnector 150. Further, each of the plurality of convex portions 192 faces the upper surface of the air electrode 114. That is, the current collector 190 has a plurality of protrusions 192 facing the upper surface of the air electrode 114. Further, the joining material 138 is provided for each of the plurality of convex portions 192 included in the current collector 190, and joins the surface of the convex portion 192 and the surface of the air electrode 114. The current collector 190 in the present embodiment corresponds to the current collector in the claims, the convex portion 192 in the present embodiment corresponds to the convex portion in the claims, and the air electrode 114 in the present embodiment corresponds to the convex portion. , Corresponds to a specific electrode in the claims.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied via a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. Then, 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 the oxidant gas introduction manifold 161 oxidizes each power generation unit 102. It is supplied to the air chamber 166 through the agent gas supply communication hole 132. Further, as shown in FIGS. 3 and 5, the fuel gas FG is supplied via a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. Then, 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 gas supply communication of each power generation unit 102 is performed from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 through the 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, power is generated by the electrochemical reaction of the oxidant gas OG and the fuel gas FG in the single cell 110. Will be. 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 the current collector 190 (the aggregate of the interconnector 150, the air pole side current collector 134 and the coat 136) via the bonding material 138. The fuel pole 116 is electrically connected to the interconnector 150 via the fuel pole side current collector 144. 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. It may be heated by (not shown).

As shown in FIGS. 2 and 4, 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, and further oxidized. 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 agent gas discharge manifold 162, and the gas pipe (not shown) connected to the branch 29. It is discharged to the outside of. Further, as shown in FIGS. 3 and 5, 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, and further, the fuel gas. Through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the discharge manifold 172, and through a gas pipe (not shown) connected to the branch 29, to the outside of the fuel cell stack 100. It is discharged.

A-3. Detailed configuration of joint material 138:
Next, the detailed configuration of the joining material 138 will be described. As shown in FIG. 5, the joining material 138 is in contact with the entire surface of the bottom surface portion 195 of the surface 194 of the convex portion 192 of the current collector 190, and is in a part of the region of the side surface portion 196 adjacent to the bottom surface portion 195. Is also in contact. Here, the side surface portion 196 is an angle θ2 formed by the virtual tangent plane TP at each point on the surface 194 of the convex portion 192 of the current collector 190 and the surface of the air electrode 114 (however, 0 degree ≦ θ2 ≦). 90 degrees) is a part composed of each point of 45 degrees or more. The bottom surface portion 195 is a portion of the surface 194 of the convex portion 192 of the current collector 190, which is surrounded by the side surface portion 196 and is composed of points having an angle θ2 of less than 45 degrees. .. Note that FIG. 5 shows a tangent plane TP at the position of the boundary between the side surface portion 196 and the bottom surface portion 195 (that is, the tangent plane TP at which the angle θ2 formed is 45 degrees).

Further, in the present embodiment, in the direction orthogonal to the Z-axis direction (for example, the Y direction, hereinafter referred to as the "plane direction"), the maximum width W1 of the joining member 138 is within the convex portion 192 of the current collector 190. It is larger than the maximum width W2 of the portion in contact with the joint material 138. The plane direction corresponds to the second direction in the claims.

Further, in the present embodiment, the contact angle θ1 (however, 0 degree ≦ θ1 ≦ 180 degrees) between the bonding material 138 and the surface of the air electrode 114 is an obtuse angle. More specifically, the contact angle θ1 between the bonding material 138 and the surface of the air electrode 114 is 110 degrees or more and 160 degrees or less. The contact angle θ1 between the joining material 138 and the surface of the air electrode 114 can be specified, for example, in accordance with JIS R3257.

Further, in the present embodiment, in the Z-axis direction, from the surface of the air electrode 114 to the position P1 of the maximum width W1 of the bonding material 138 with respect to the height t2 of the air chamber 166 which is a gas chamber facing the surface of the air electrode 114. The ratio of the distances t1 (t1 / t2) is 0.02 or more. The ratio (t1 / t2) is preferably 0.1 or less. The distance t1 is preferably 10 μm or more and 50 μm or less, and the height t2 is preferably 500 μm or more and 700 μm or less, for example.

A-4. Effect of this embodiment:
As described above, each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment includes the electrolyte layer 112, the air poles 114 and the fuel poles 116 facing each other in the Z-axis direction with the electrolyte layer 112 interposed therebetween. A single cell 110 including the above, a conductive current collector 190 having a plurality of convex portions 192 facing the surface of the air electrode 114, and an air electrode provided for each of the plurality of convex portions 192. A conductive bonding material 138 for bonding the surface of 114 is provided. Further, in the power generation unit 102 of the present embodiment, the joining material 138 provided for each convex portion 192 satisfies the following requirements (a), (b), and (c).
(A) The joining material 138 is in contact with the bottom surface portion 195 of the convex portion 192 and a part of the side surface portion 196 of the convex portion 192 adjacent to the bottom surface portion 195.
(B) In the direction orthogonal to the Z-axis direction (plane direction), the maximum width W1 of the joining material 138 is larger than the maximum width W2 of the portion of the convex portion 192 in contact with the joining material 138.
(C) The contact angle θ1 between the bonding material 138 and the surface of the air electrode 114 is an obtuse angle.

Since the power generation unit 102 of the present embodiment has the above configuration, as described below, it is caused by suppressing the performance deterioration of the power generation unit 102 due to the increase in contact resistance and increasing the gas diffusion resistance. It is possible to effectively achieve both suppression of performance deterioration of the power generation unit 102.

FIG. 8 is an explanatory diagram showing the configuration of the power generation unit 102X in the first comparative example. In the power generation unit 102X of the first comparative example shown in FIG. 8, the contact angle θ1 between the bonding material 138 and the surface of the air electrode 114 is an acute angle. That is, the power generation unit 102X of the first comparative example does not satisfy the above requirement (c). Since the power generation unit 102X of the first comparative example does not satisfy the above requirement (c), the region covered by the bonding material 138 on the surface of the air electrode 114 becomes large, and as a result, the gas diffusion resistance increases and the power generation unit The performance of 102 is reduced.

Further, FIG. 9 is an explanatory diagram showing the configuration of the power generation unit 102Y in the second comparative example. In the power generation unit 102Y of the second comparative example shown in FIG. 9, the joining material 138 is in contact with a part of the bottom surface portion 195 of the convex portion 192, but is not in contact with the side surface portion 196 of the convex portion 192. .. That is, the power generation unit 102Y of the second comparative example does not satisfy the above requirement (a). Since the power generation unit 102Y of the second comparative example does not satisfy the above requirement (a), it is not possible to sufficiently secure a conductive path between the convex portion 192 of the current collector 190 and the bonding material 138. As a result, the contact resistance increases and the performance of the power generation unit 102 deteriorates.

On the other hand, in the power generation unit 102 of the present embodiment, the bonding material 138 is in contact with a part of the side surface portion 196 of the convex portion 192 in addition to the bottom surface portion 195 of the convex portion 192 of the current collector 190. Since the cage (the above requirement (a)) and the maximum width W1 of the bonding material 138 is larger than the maximum width W2 of the convex portion 192 of the current collector 190 (the above requirement (b)), the convex portion 192 of the current collector 190. It is possible to sufficiently secure a conductive path between the bonding material 138 and the bonding material 138, and as a result, it is possible to suppress a deterioration in the performance of the power generation unit 102 due to an increase in contact resistance. Further, in the power generation unit 102 of the present embodiment, since the contact angle θ1 between the bonding material 138 and the surface of the air electrode 114 is an obtuse angle (the above requirement (c)), the above requirements (a) and (b) are satisfied. Even if the above is adopted, the region covered by the bonding material 138 on the surface of the air electrode 114 can be reduced, and as a result, the performance deterioration of the power generation unit 102 due to the increase in gas diffusion resistance can be suppressed. Therefore, according to the power generation unit 102 of the present embodiment, it is effective to suppress the performance deterioration of the power generation unit 102 due to the increase in contact resistance and the performance deterioration of the power generation unit 102 due to the increase in gas diffusion resistance. Can be compatible with. It was confirmed that by adopting the above configuration, a current can be passed at a ^{current density of 0.7 A / cm 2.}

Further, in the power generation unit 102 of the present embodiment, the contact angle θ1 between the bonding material 138 and the surface of the air electrode 114 is 110 degrees or more and 160 degrees or less. Therefore, according to the power generation unit 102 of the present embodiment, the conductive path between the convex portion 192 of the current collector 190 and the bonding material 138 is secured, and the area of the region covered by the bonding material 138 on the surface of the air electrode 114 is secured. It is possible to achieve both reduction and reduction in a well-balanced manner, and it is possible to effectively suppress performance deterioration of the power generation unit 102. The contact angle θ1 between the bonding material 138 and the surface of the air electrode 114 is more preferably 120 degrees or more and 150 degrees or less, and further preferably 130 degrees or more and 140 degrees or less.

Further, in the power generation unit 102 of the present embodiment, the maximum width W1 of the bonding material 138 from the surface of the air electrode 114 with respect to the height t2 of the air chamber 166, which is a gas chamber facing the surface of the air electrode 114, in the Z-axis direction. The ratio of the distance t1 to the position P1 (t1 / t2) is 0.02 or more. As described above, in the power generation unit 102 of the present embodiment, since the ratio (t1 / t2) is as large as 0.02 or more, the portion having the maximum width in the bonding material 138 (the portion at position P1 in FIG. 5) is Since it is separated from the surface of the air electrode 114 to some extent, it is possible to prevent the bonding material 138 from obstructing the flow of the oxidant gas OG near the surface of the air electrode 114, and this is due to an increase in gas diffusion resistance. It is possible to effectively suppress the deterioration of the performance of the power generation unit 102. The above ratio is more preferably 0.03 or more, and further preferably 0.04 or more. The ratio (t1 / t2) is preferably 0.1 or less. In such a configuration, since the ratio (t1 / t2) is not excessive at 0.1 or less, it is possible to prevent the angle formed by the convex portion 192 of the current collector 190 and the bonding material 138 from becoming too steep. Therefore, the bondability between the convex portion 192 and the bonding material 138 can be ensured. The above ratio is more preferably 0.09 or less, and further preferably 0.08 or less.

A-5. Manufacturing method of fuel cell stack 100:
Next, a method of manufacturing the fuel cell stack 100 will be described. FIG. 10 is a flowchart showing an example of a method for manufacturing the fuel cell stack 100 according to the present embodiment. Further, FIG. 11 is an explanatory diagram showing an outline of a method of manufacturing the power generation unit 102 among the methods of manufacturing the fuel cell stack 100 in the present embodiment.

First, a single cell 110 and a current collector 190 are manufactured (S110). Since the single cell 110 and the current collector 190 can be manufactured by a known method, the description of the manufacturing method will be omitted here.

Next, the paste PA for the bonding material 138 is applied to each convex portion 192 of the current collector 190 (S120, A in FIG. 11). In the present embodiment, the paste PA is applied to a part of the bottom surface portion 195 of the convex portion 192 of the current collector 190. In the present embodiment, the viscosity of the applied paste PA is set to 60 Pa · s or more and 150 Pa · s or less. In the present specification, the viscosity of the paste PA is the viscosity measured at room temperature of 23 ° C. using a No. 2 rotor of a viscometer (VT-04F) manufactured by Rion Co., Ltd. Further, in the present embodiment, the coating thickness d of the paste PA is set to 20 μm or more and 50 μm or less. The step of S120 corresponds to the first step in the claims.

After the paste PA is applied in S120, the current collector 190 is brought closer to the single cell 110 along the Z-axis direction without performing a process of raising the temperature of the paste PA (for example, a drying process). The paste PA applied to the bottom surface portion 195 of the convex portion 192 of the above is brought into contact with the surface of the air electrode 114 (S130, B in FIG. 11). As a result, the paste PA is deformed so as to be in contact with the entire region of the bottom surface portion 195 of the convex portion 192 and a part of the side surface portion 196 (see arrow B2 in FIG. 11B). The step of S130 corresponds to the second step in the claims, and the state in which the paste PA is in contact with the surface of the air electrode 114 corresponds to the specific state in the claims.

Next, the paste PA is kept in contact with the surface of the air electrode 114 for a predetermined time (S140). The step of S140 corresponds to the third step in the claims.

Next, the paste PA is cured by performing a process of raising the temperature of the paste PA to form the bonding material 138 (S150, C in FIG. 11). As a result, the power generation unit 102 having a structure in which each convex portion 192 of the current collector 190 and the surface of the air electrode 114 are joined by the joining material 138 is manufactured. The treatment for raising the temperature of the paste PA is, for example, a heat treatment, a reduction treatment, or an energization treatment.

A plurality of power generation units 102 are manufactured by the above-mentioned manufacturing method, and an assembly step of assembling the manufactured plurality of power generation units 102 and other members is performed (S160). Through the above steps, the fuel cell stack 100 having the above-described configuration is manufactured.

As described above, the method of manufacturing the power generation unit 102 in the method of manufacturing the fuel cell stack 100 of the present embodiment is for the bonding material 138 on the bottom surface portion 195 of the surface 194 of each convex portion 192 of the current collector 190. After step S120 for applying the paste PA and after step S120, the paste PA becomes an air electrode by bringing the current collector 190 closer to the single cell 110 along the Z-axis direction without performing a process of raising the temperature of the paste PA. Step S130 to form the state of contact with the surface of 114, and step S140 to keep the paste PA in contact with the surface of the air electrode 114 for a predetermined time after step S130, and after step S140, the paste PA A step S150 for forming the bonding material 138 by performing a process of raising the temperature is provided.

As described above, in the method for producing the power generation unit 102 of the present embodiment, since the process of raising the temperature of the paste PA is not performed in step S130, the change in the viscosity of the paste PA from the time of coating in S120 (the viscosity due to heating). Decrease and increase in viscosity due to drying) are suppressed. By suppressing the decrease in the viscosity of the paste PA from the time of application, an unintended change in the shape of the paste PA (excessive spread in the plane direction) is suppressed. Further, by suppressing the increase in the viscosity of the paste PA from the time of application, the occurrence of poor contact between the paste PA and the surface 194 (particularly, the side surface portion 196) of the convex portion 192 is suppressed.

Further, in the method for manufacturing the power generation unit 102 of the present embodiment, after step S130, step S140 for maintaining the state in which the paste PA is in contact with the surface of the air electrode 114 is performed for a predetermined time. In the portion near the surface of the air electrode 114, the viscosity of the paste PA is further increased by penetrating into the relatively porous air electrode 114 (see arrow B1 in FIG. 11B), and as a result, The spread of the paste PA in the plane direction is effectively suppressed. On the other hand, in the portion of the paste PA near the convex portion 192 of the current collector 190, the viscosity is generally maintained, so that the paste PA is formed from the bottom surface portion 195 to the side surface portion 196 of the convex portion 192 of the current collector 190. Spreads well (see arrow B2 in B of FIG. 11). After that, step S150 for forming the bonding material 138 by raising the temperature of the paste PA is performed, so that the spread in the plane direction is suppressed in the vicinity of the surface of the air electrode 114, and the convex portion 192 of the current collector 190 is suppressed. In the vicinity, a joining material 138 having a shape extending from the bottom surface portion 195 of the convex portion 192 toward the side surface portion 196 is formed. That is, the formed joining material 138 satisfies the above-mentioned requirements (a) to (c).

As described above, according to the method for manufacturing the power generation unit 102 of the present embodiment, it is possible to manufacture the power generation unit 102 including the bonding material 138 satisfying the above-mentioned requirements (a) to (c). Therefore, according to the manufacturing method of the power generation unit 102 of the present embodiment, it is possible to effectively achieve both suppression of performance deterioration due to an increase in contact resistance and suppression of performance deterioration due to an increase in gas diffusion resistance. It is possible to manufacture a power generation unit 102 capable of producing.

Further, as described above, in the method for manufacturing the power generation unit 102 of the present embodiment, the viscosity of the paste PA applied in S120 is set to 60 Pa · s or more and 150 Pa · s or less. By setting the viscosity of the paste PA applied in S120 to 60 Pa · s or more, it is possible to effectively suppress an unintended change in the shape of the paste PA (excessive spread in the plane direction) in the subsequent steps. Further, by setting the viscosity of the paste PA applied in S120 to 150 Pa · s or less, the paste PA can be smoothly applied to the convex portion 192 of the current collector 190. Further, when the viscosity of the paste PA applied in S120 is set to 60 Pa · s or more and 150 Pa · s or less, the assembling load is suppressed to about 0.2 to 0.6 MPa, so that the single cell 110 is cracked. Can be suppressed.

Further, as described above, in the method for manufacturing the power generation unit 102 of the present embodiment, the thickness d of the paste PA applied in S120 is set to 20 μm or more and 50 μm or less. By setting the thickness d of the paste applied in step S120 to 20 μm or more, when the paste PA is formed in contact with the surface of the air electrode 114 in step S130, the dimensional variation of each member is absorbed by the paste PA. It is possible to realize reliable bonding and electrical connection by the bonding material 138. Further, by setting the thickness d of the paste PA applied in S120 to 50 μm or less, it is possible to prevent the width of the bonding material 138 formed from the paste PA in the plane direction from becoming excessive and increasing the gas diffusion resistance. be able to.

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, and for example, the following modifications are also possible.

The configuration of the single cell 110, the power generation unit 102, or the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, the joining material 138 is in contact with only a part of the side surface portion 196 of the convex portion 192, but the joining material 138 may be in contact with the entire region in the side surface portion 196.

Further, in the above embodiment, the contact angle θ1 between the joining material 138 and the surface of the air electrode 114 is 110 degrees or more and 160 degrees or less, but if the contact angle θ1 is an obtuse angle, it is 110 degrees or more. It may be out of the range of 160 degrees or less.

Further, in the above embodiment, in the Z-axis direction, from the surface of the air electrode 114 to the position P1 of the maximum width W1 of the bonding material 138 with respect to the height t2 of the air chamber 166 which is a gas chamber facing the surface of the air electrode 114. The ratio (t1 / t2) of the distance t1 is 0.02 or more, but the ratio (t1 / t2) may be less than 0.02.

Further, in the above embodiment, the interconnector 150 and the air electrode side current collector 134 (current collector element 135) are integrated members, but both may be separate members. In such a configuration, the current collector 190 is composed of the air electrode side current collector 134 (current collector element 135) and the coat 136. Further, in the above embodiment, the air electrode side current collector 134 (current collector element 135) is covered with the coat 136, but the air electrode side current collector 134 may not be covered with the coat 136. In such a configuration, the current collector 190 does not include the coat 136.

Further, in the above embodiment, the single cell 110 includes the intermediate layer 180, but the single cell 110 does not necessarily have to include the intermediate layer 180. Further, in the above embodiment, the number of single cells 110 (power generation unit 102) included in the fuel cell stack 100 is only an example, and the number of single cells 110 (power generation unit 102) is required for the fuel cell stack 100. It is appropriately determined according to the output voltage and the like. Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

Further, the constituent requirements described in the above embodiment (for example, the above requirements (a) to (c) regarding the bonding material 138) need not necessarily be satisfied in all of the plurality of power generation units 102 constituting the fuel cell stack 100. However, it may be satisfied in at least one of the plurality of power generation units 102 constituting the fuel cell stack 100. Further, when focusing on one power generation unit 102, the constituent requirements do not necessarily have to be satisfied in all of the plurality of convex portions 192 included in the current collector 190, and the plurality of convex portions included in the current collector 190. It suffices if at least one of the parts 192 is satisfied. In addition, in order to effectively both suppress the performance deterioration due to the increase in contact resistance and the performance deterioration due to the increase in gas diffusion resistance in the power generation unit 102, all the convex portions 192 included in the current collector 190. Of these, 30% or more of the convex portions 192 preferably satisfy the above-mentioned constituent requirements, 50% or more of the convex portions 192 preferably satisfy the above-mentioned constituent requirements, and 70% or more of the convex portions 192 satisfy the above-mentioned constituent requirements. It is more preferable that the above-mentioned constituent requirements are satisfied in 192, more preferably the above-mentioned constituent requirements are satisfied in 90% or more of the convex portions 192, and the above-mentioned constituent requirements are satisfied in 100% of the convex portions 192. Most preferably.

Further, the method for manufacturing the fuel cell stack 100 and the power generation unit 102 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, the viscosity of the paste PA is set to 60 Pa · s or more and 150 Pa · s or less, but the viscosity of the paste PA does not necessarily have to be set within this range. Further, in the above embodiment, the coating thickness d of the paste PA is set to 20 μm or more and 50 μm or less, but the coating thickness d of the paste PA does not necessarily have to be set within this range. Further, in the above embodiment, the paste PA is applied to a part of the bottom surface portion 195 of each convex portion 192 of the current collector 190, but the paste PA may be applied to the entire area of the bottom surface portion 195. Then, the paste PA may be applied not only to the bottom surface portion 195 but also to the side surface portion 196.

Further, in the above embodiment, in step S130, the paste PA is in contact with the surface of the air electrode 114 by bringing the current collector 190 close to the single cell 110 along the Z-axis direction, but this is not necessarily the case. It is not necessary to do so, and the paste PA may be in contact with the surface of the air electrode 114 by relatively moving the current collector 190 and the single cell 110 in the Z-axis direction.

Further, in the above embodiment, the characteristics of the bonding material 138 for joining the air electrode 114 and the current collector 190 having a plurality of convex portions 192 facing the surface of the air electrode 114 have been described, but the fuel electrode 116 and the fuel electrode 116 When a joining material for joining a current collector having a plurality of convex portions facing the surface of the fuel electrode 116 is used, the present invention can be applied to the joining material as well.

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 relates to the electrolysis reaction of water. It is also applicable to an electrolytic cell unit, which is a constituent unit of a solid oxide type electrolytic cell (SOEC) that generates hydrogen by utilizing it, 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 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 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, by adopting the bonding material having the same configuration as that of the above embodiment, the performance deterioration due to the increase in contact resistance can be suppressed and the gas diffusion resistance can be increased. It is possible to effectively achieve both suppression of performance deterioration due to it.

Further, in the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example, but the present invention also applies to other types of fuel cells (or electrolytic cells) such as a molten carbonate fuel cell (MCFC). Applicable.

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 100: Fuel cell stack 102: Fuel cell power generation unit 104: End plate 106: End plate 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: Fuel pole 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 Polar side current collector 135: Current collector element 136: Coat 138: Bonding material 140: Fuel pole side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel pole side current collector 145 : Electrode facing part 146: Interconnector facing part 147: Connecting part 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 180: Intermediate layer 190: Current collector 192: Convex part 194: Surface 195: Bottom part 196: Side part

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.
It is a conductive current collector having a plurality of convex portions facing the surface of a specific electrode having one of the air electrode and the fuel electrode, and the surface of the convex portion is each on the surface of the convex portion. A side surface portion formed by each point having an angle formed by a virtual tangent plane at a point and the surface of the specific electrode of 45 degrees or more, and a side surface portion surrounded by the side surface portion and having an angle of less than 45 degrees. The current collector, including a bottom portion composed of dots,
A conductive bonding material provided for each of the plurality of convex portions and for joining the surface of the convex portion and the surface of the specific electrode.
In an electrochemical reaction unit comprising
For the joining material provided for at least one of the protrusions
(A) The joining material is in contact with the bottom surface portion of the convex portion and at least a part of the side surface portion of the convex portion adjacent to the bottom surface portion.
(B) In the second direction orthogonal to the first direction, the maximum width of the joining material is larger than the maximum width of the portion of the convex portion in contact with the joining material, and
(C) The contact angle between the bonding material and the surface of the specific electrode is an obtuse angle.
An electrochemical reaction unit characterized by the fact that. In the electrochemical reaction unit according to claim 1,
An electrochemical reaction unit, wherein the contact angle between the bonding material and the surface of the specific electrode is 110 degrees or more and 160 degrees or less. In the electrochemical reaction unit according to claim 1 or 2.
In the first direction, the ratio (t1 / t2) of the distance t1 from the surface of the specific electrode to the position of the maximum width of the bonding material with respect to the height t2 of the gas chamber facing the surface of the specific electrode is , An electrochemical reaction unit characterized by being 0.02 or more. In the electrochemical reaction unit according to any one of claims 1 to 3.
The electrochemical reaction single cell is an electrochemical reaction unit, which is a fuel cell single cell. 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 4. 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.
It is a conductive current collector having a plurality of convex portions facing the surface of a specific electrode having one of the air electrode and the fuel electrode, and the surface of the convex portion is each on the surface of the convex portion. A side surface portion formed by each point having an angle formed by a virtual tangent plane at a point and the surface of the specific electrode of 45 degrees or more, and a side surface portion surrounded by the side surface portion and having an angle of less than 45 degrees. The current collector, including a bottom portion composed of dots,
A conductive bonding material provided for each of the plurality of convex portions and for joining the surface of the convex portion and the surface of the specific electrode.
In the method for producing an electrochemical reaction unit comprising
(A) The joining material is in contact with the bottom surface portion of the convex portion and at least a part of the side surface portion of the convex portion adjacent to the bottom surface portion.
(B) In the second direction orthogonal to the first direction, the maximum width of the joining material is larger than the maximum width of the portion of the convex portion in contact with the joining material, and
(C) The contact angle between the bonding material and the surface of the specific electrode is an obtuse angle.
The method for producing the electrochemical reaction unit is as follows.
The first step of applying the paste for the joining material to at least the bottom surface portion of the surface of each of the convex portions of the current collector.
After the first step, the paste is identified by relatively moving the current collector and the electrochemical reaction single cell in the first direction without performing a process of raising the temperature of the paste. The second step of forming a specific state in contact with the surface of the electrode, and
After the second step, a third step of maintaining the specific state for a predetermined time and
After the third step, a fourth step of forming the bonding material by performing a process of raising the temperature of the paste, and
A method for producing an electrochemical reaction unit, which comprises. In the method for producing an electrochemical reaction unit according to claim 6,
The first step is a step of applying the paste of 60 Pa · s or more and 150 Pa · s or less, which is a method for producing an electrochemical reaction unit. In the method for producing an electrochemical reaction unit according to claim 6 or 7.
The first step is a step of applying the paste to a thickness of 20 μm or more and 50 μm or less, which is a method for producing an electrochemical reaction unit.

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