Fuel cell and method for manufacturing the same

Abstract

To prevent leak of a reactive gas from a welding portion of an electrode and an interconnector.SOLUTION: A fuel battery comprises a plurality of power generation cells each having a solid electrolyte plate, an anode electrode and a cathode electrode, in which the plurality of power generation cells are laminated through first and second interconnectors in a thickness direction. In the fuel battery, at least one of the anode and cathode electrodes has a support layer formed by a metal porous body. The first interconnector has a plurality of first ribs in parallel with each other. The first ribs are welded to the support layer to form a first reaction gas passage between adjacent first ribs. An opening of the first rib is sealed by joining the second interconnector thereto. To a face of the second interconnector on the side opposite to the first interconnector, the other power generation cell is joined.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fuel cell and a method for manufacturing a fuel cell. [Background technology]

[0002] Patent Document 1 discloses a fuel cell stack having a solid electrolyte cell in which an air electrode current collector made of a porous sintered metal plate provided with reinforcing expanded metal and a separator are joined by spot welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-263994 A Summary of the Invention [Problem to be solved by the invention]

[0004] Welding is a low-cost joining method because it has relatively low electrical resistance after joining, is robust, and does not require additional materials. However, when welding a separator and a porous metal, there is a problem that welding defects such as so-called blowholes are likely to occur due to the expansion of air in the holes or the generation of gas due to foreign matter attached to the interface. If a blowhole occurs, the anode gas flow path and the cathode gas flow path defined by the separator will communicate with each other, causing the problem that the anode gas and the cathode gas cannot be separated.

[0005] Therefore, an object of the present invention is to provide a fuel cell and a method for manufacturing the fuel cell that can prevent communication between the anode gas flow path and the cathode gas flow path while using welding to join the porous metal body as the support layer for the electrodes to the separator. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a fuel cell in which a plurality of power generation cells, each having a solid electrolyte plate, an anode electrode disposed on one surface of the solid electrolyte plate, and a cathode electrode disposed on the other surface of the solid electrolyte plate, are stacked in the thickness direction via a first interconnector and a second interconnector. and Cathode voltage The pole The support layer is made of a metal porous body, and the first interconnector is The anode electrode support layer side The plate has a plurality of first ribs that are parallel to each other and protrude from the plate and extend in a direction perpendicular to the thickness direction. It has a corrugated plate shape , and the top of the first rib is Anode electrode The first ribs are welded to the support layer to form a first reactant gas flow path between adjacent first ribs. The second interconnector has a corrugated plate shape having a plurality of second ribs that protrude in the thickness direction toward the support layer side of the anode electrode and extend in a direction perpendicular to the thickness direction and are parallel to each other. In addition, the first interconnector Anode electrode The opening of the first rib when viewed from the opposite side to the support layer is rib The second interconnector is joined to the surface of the second interconnector opposite to the first interconnector, and another power generating cell is joined to the surface of the second interconnector opposite to the first interconnector. Effect of the Invention

[0007] According to the above aspect, while welding is used to join the porous metal body serving as the support layer of the electrode to the separator, communication between the anode gas flow channel and the cathode gas flow channel can be prevented. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a power generation unit according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the power generation unit according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of the power generation units in a stacked state. [Figure 4] FIG. 4 is a plan view showing a linear flow channel. [Diagram 5] FIG. 5 is an exploded perspective view of a joint portion of two interconnectors when the flow paths are linear. [Figure 6] FIG. 6 is a diagram showing a schematic diagram of the relationship between the welded portion and the joint portion. [Figure 7] FIG. 7 is a plan view showing staggered flow channels. [Figure 8] FIG. 8 is an exploded perspective view of a joint portion of two interconnectors when the flow channels are staggered. [Figure 9] FIG. 9 is a cross-sectional view of a power generation unit according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view when the second interconnector is a flat plate. [Figure 11] FIG. 11 is a cross-sectional view of a power generation unit according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] [First embodiment] In the following description, the direction along the thickness of the power generation unit 1 (z-axis direction in the figure) is referred to as the thickness direction, the longitudinal direction of the power generation unit 1 (y-axis direction) is referred to as the longitudinal direction, and the direction perpendicular to the thickness direction and longitudinal direction (x-axis direction) is referred to as the width direction.

[0011] Fig. 1 is a perspective view of a power generation unit 1 constituting a power generation module of a fuel cell according to this embodiment. Fig. 2 is an exploded configuration diagram of the power generation unit 1. Fig. 3 is a cross-sectional view perpendicular to the longitudinal direction and thickness direction, showing a state in which two power generation units 1 (a first unit and a second unit) are stacked.

[0012] The power generating unit 1 comprises a power generating cell 2, a first interconnector 4 joined to one surface of the power generating cell 2, and a second interconnector 3 joined to the other surface of the power generating cell 2.

[0013] The power generating cell 2 comprises a solid electrolyte plate 2A, an anode electrode 2C disposed on one surface of the solid electrolyte plate 2A, and a cathode electrode 2B disposed on the other surface of the solid electrolyte plate 2A. The cathode electrode 2B and the anode electrode 2C each have a support layer formed of a metal porous body. Hereinafter, the support layer of the cathode electrode 2B is also referred to as the cathode support layer, and the support layer of the anode electrode 2C is also referred to as the anode support layer.

[0014] The first interconnector 4 has a plurality of first ribs 4A that protrude in the thickness direction and extend in a direction (longitudinal direction) perpendicular to the thickness direction and are parallel to each other. The top of each of the first ribs 4A is welded to the anode support layer. This forms a first reactant gas flow path 8 through which the anode gas flows between adjacent first ribs 4A. In the following description, the portion where the first rib 4A and the anode support layer are welded is also referred to as a first welded portion 6.

[0015] The second interconnector 3 has a plurality of second ribs 3A that protrude in the thickness direction and extend in a direction (longitudinal direction) perpendicular to the thickness direction and are parallel to each other. The second interconnector 3 has a portion between adjacent second ribs 3A welded to the cathode support layer. This forms a second reactant gas flow path 9 through which the cathode gas flows between adjacent second ribs 3A. In the following description, the portion where the second rib 3A and the cathode support layer are welded is also referred to as a second welded portion 5.

[0016] The power generation unit 1, which is composed of the power generation cell 2, the first interconnector 4, and the second interconnector 3, is defined as a unit, and the power generation module is formed by stacking these unit units in the thickness direction.

[0017] In joining two unitary units (first unit and second unit), the second interconnector 3 of the second unit is joined to the first interconnector 4 of the first unit. In the joined state, the opening of the first rib 4A of the first unit is sealed by the second rib 3A of the second unit. The joining here is performed, for example, by metal solid-phase diffusion, which involves heating and warming the first rib 4A and the second rib 3A in contact with each other. Alternatively, a method may be used in which the contact portion having a large electrical resistance is locally heated by passing an electric current through the first rib 4A and the second rib 3A in contact with each other. In the following description, the portion where the first rib 4A and the second rib 3A are joined is also referred to as a joint 7.

[0018] The width of the first rib 4A increases as it moves away from the first welded portion 6, and the width of the second rib 3A increases as it moves away from the joint portion 7. The maximum width of the first rib 4A is equal to or less than the minimum width of the second rib 3A, and the inclination angle of the inclined surface from the flat portion 4B of the first rib 4A toward the first welded portion 6 is smaller than the inclination angle of the inclined surface from the flat portion 3B of the second rib 3A toward the joint portion 7. This causes the inclined surface of the second rib 3A to abut against the inclined surface of the first rib 4A, making it easy to control the contact position between the first rib 4A and the second rib 3A. In addition, the amount of forming by bending the interconnectors 3 and 4 is suppressed, so that damage during processing can be prevented. Next, the flow path shape of each interconnector 3 and 4 will be described.

[0019] Fig. 4A is a plan view of the first interconnector 4, and Fig. 4B is a plan view of the second interconnector 3. As shown in the figure, the first rib 4A and the second rib 3A are both linearly shaped and extend in the longitudinal direction. That is, the first reactant gas flow channel 8 and the second reactant gas flow channel 9 are linear flow channels.

[0020] Fig. 5 is an exploded perspective view of the first interconnector 4 and the second interconnector 3 joined as shown in Fig. 3. The first welded portion 6 extends linearly in the flow path direction along the top (upper surface here) of the first interconnector 4. The joint portion 7 is composed of two straight portions 7A parallel to the first welded portion 6, and a curved portion 7B connecting the ends of the two straight portions 7A. This is because both the first rib 4A and the second rib 3A have a shape with closed ends.

[0021] Fig. 6 is a schematic diagram showing the positional relationship between the first welded portion 6 and the joint portion 7 as viewed from the thickness direction. As shown in Fig. 6, the first welded portion 6 is surrounded by the joint portion 7. In other words, when the first interconnector 4 is viewed from the side opposite to the anode support layer, the opening of the first rib 4A is sealed by the joining of the second interconnector 3. The effect of this will be described referring back to Fig. 3.

[0022] As described above, when the anode electrode 2C (anode support layer) made of a porous metal body is welded to the first interconnector 4, there is a risk of a welding defect such as a blowhole occurring. For example, if a blowhole occurs near the first welded portion 6 of the first rib 4A, the first reactant gas flow channel 8 communicates with the inside of the first rib 4A (S in FIG. 3) through the blowhole. However, if the opening of the first rib 4A is sealed by the second rib 3A as in this embodiment, the reactant gas flowing through the first reactant gas flow channel 8 can be prevented from leaking to the outside.

[0023] In this embodiment, the first rib 4A and the second rib 3A are linear, but the same applies to the case where the respective ribs 4A, 3A are formed in a staggered pattern as shown in Figs. 7 and 8.

[0024] As described above, in this embodiment, a fuel cell is provided in which a plurality of power generating cells 2 each having a solid electrolyte plate 2A, an anode electrode 2C disposed on one surface of the solid electrolyte plate 2A, and a cathode electrode 2B disposed on the other surface of the solid electrolyte plate 2A are stacked in the thickness direction via a first interconnector 4 and a second interconnector 3. At least one of the anode electrode 2C and the cathode electrode 2B has a support layer formed of a metal porous body, and the first interconnector 4 has a plurality of first ribs 4A that are parallel to each other and protrude in the thickness direction and extend in a direction perpendicular to the thickness direction, and the tops of the first ribs 4A are welded to the support layer to form a first reactant gas flow path 8 between adjacent first ribs 4A. When the first interconnector 4 is viewed from the opposite side to the support layer, the opening of the first rib 4A is sealed by joining the second interconnector 3. Another power generating cell 2 is joined to the surface of the second interconnector 3 opposite to the first interconnector 4. As a result, even if a welding defect such as a blowhole occurs near the welded portion (first welded portion 6) between the first interconnector 4 and the support layer and the reaction gas leaks from the first reaction gas flow path 8 into the internal space S of the first rib 4A, the opening of the first rib 4A is sealed by the second interconnector 3, so the reaction gas will not leak to the outside.

[0025] In this embodiment, the second interconnector 3 has a plurality of groove-shaped second ribs 3A protruding in the thickness direction, and the second ribs 3A seal the openings of the first rib 4A. The cross section of the first rib 4A perpendicular to the longitudinal direction is wider as it moves away from the welded portion (first welded portion 6) with the support layer, and the cross section of the second rib 3A perpendicular to the longitudinal direction is wider as it moves away from the joint portion 7 with the first rib 4A, and the maximum width of the first rib 4A is equal to or smaller than the minimum width of the second rib 3A, and the inclination angle of the inclined surface from the flat portion 4B of the first rib 4A to the first welded portion 6 is smaller than the inclination angle of the inclined surface from the flat portion 3B of the second rib 3A to the joint portion 7. This makes it easy to control the contact position between the first rib 4A and the second rib 3A. In addition, the amount of forming by bending the interconnectors 3 and 4 is suppressed, so that damage during processing can be prevented.

[0026] In this embodiment, the first interconnector 4 and the second interconnector 3 are joined by metal solid-state diffusion or local heating by passing an electric current. According to these joining methods, the first interconnector 4 and the second interconnector 3 can be firmly joined without damaging the periphery of the joint.

[0027] [Second embodiment] 9 is a cross-sectional view perpendicular to the longitudinal direction and thickness direction, showing a state in which power generation units 1 according to the second embodiment are stacked. The difference from FIG. 3 is that the inclined surfaces of the first rib 4A and the second rib 3A are provided with communication holes 10 and 11.

[0028] The inclined surface of the first rib 4A has the communication holes 11, so that the first reactant gas flow path 8 communicates with the space S inside the first rib 4A. As described in the first embodiment, the opening of the first rib 4A is sealed by the second rib 3A. Therefore, not only the first reactant gas flow path 8 but also the space S inside the first rib 4A serves as a flow path through which the first reactant gas flows. As a result, the flow path area for the first reactant gas is increased compared to the first embodiment, and pressure loss is reduced.

[0029] Since the inclined surface of the second rib 3A has the communication holes 10, the second reactant gas flow path 9 communicates with a space T defined by the adjacent second rib 3A and the flat surface portion 4B of the first interconnector 4. The contact portion between the first rib 4A and the second rib 3A is joined. Therefore, not only the second reactant gas flow path 9 but also the space T becomes a flow path through which the second reactant gas flows. As a result, the flow path area for the second reactant gas is increased compared to the first embodiment, and the pressure loss is reduced.

[0030] In the first and second embodiments, the second interconnector 3 includes the second rib 3A, but the second interconnector 3 may be a flat plate.

[0031] FIG. 10 is a cross-sectional view of the vicinity of the joint between first interconnector 4 and second interconnector 3 when second interconnector 3 is a flat plate.

[0032] When the second interconnector 3 is a flat plate, the first welds 6 are provided at every other contact portion between the first interconnector 4 and the anode support layer aligned in the width direction. The second welds 5 are provided at positions facing the openings of the first ribs 4A where no first welds 6 are provided. The joints 7 are provided at the contact portion between the flat portion 4B of the first interconnector 4 and the second interconnector 3. In addition, a communication hole 11 is provided in the inclined surface of the first rib 4A having the first welds 6.

[0033] As a result, not only the first reaction gas flow path 8 between adjacent first ribs 4A, but also the inside of the first rib 4A including the first welded portion 6 becomes a flow path for the first reaction gas. Even if a blowhole occurs near the first welded portion 6, the opening of the first rib 4A including the first welded portion 6 is sealed by the joint 7, so that the first reaction gas will not leak to the outside.

[0034] A second reactant gas flow path 9 is defined by the inside of the first rib 4A not having the first welded portion 6 and the second interconnector 3. A communication hole 10 is provided on the surface of the second interconnector 3 facing the second reactant gas flow path 9. Since the first rib 4A does not have the first welded portion 6 in the portion where the second reactant gas flow path 9 and the first reactant gas flow path 8 are adjacent to each other, blowholes and the like are not generated. Therefore, the first reactant gas and the second reactant gas are not mixed.

[0035] As described above, in this embodiment, the inclined surface of the first rib 4A is provided with the communication holes 11 that communicate the space between the adjacent first ribs 4A (first reactant gas flow path 8) with the space S inside the first rib 4A. This increases the flow path area for the first reactant gas, thereby reducing the pressure loss of the first reactant gas.

[0036] In this embodiment, the inclined surface of the second rib 3A is provided with communication holes 10 that communicate the space T between the adjacent second ribs 3A with the space inside the second rib 3A (second reactant gas flow path 9). This increases the flow path area for the second reactant gas, thereby reducing the pressure loss of the second reactant gas.

[0037] [Third embodiment] In the first embodiment, the cathode electrode 2B and the anode electrode 2C each have a support layer, but the scope of the present invention is not limited to this, and only one of the electrodes may have a support layer. In the present embodiment, a case where a support layer is provided only on the anode electrode 2C will be described.

[0038] Fig. 11 is a cross-sectional view perpendicular to the longitudinal direction and thickness direction, showing a state in which the first unit and the second unit are stacked in this embodiment. The difference from Fig. 3 is that the second interconnector 3 and the cathode electrode 2B are not joined by welding. This is because the cathode electrode 2B does not have a support layer of a metal porous body, and therefore cannot be welded to the second interconnector 3. For the joining here, a joining method using a joining material such as contact paste is used.

[0039] In the first embodiment, the anode electrode 2C and the first interconnector 4 are welded, and the cathode electrode 2B and the second interconnector 3 are welded. In a state where the second interconnector 3 is joined to the first interconnector 4, a welding machine cannot access a contact portion between the second interconnector 3 and the cathode electrode 2B. For this reason, a unit is formed by welding the first interconnector 4 to the anode electrode 2C and welding the second interconnector 3 to the cathode electrode 2B.

[0040] In contrast, when the second interconnector 3 and the cathode electrode 2B are joined with a contact paste or the like as in this embodiment, joining is possible even in a state in which the second interconnector 3 is joined to the first interconnector 4. In other words, the first interconnector 4 is welded to the anode electrode 2C of the power generation cell 2, and the second interconnector 3 is joined to the first interconnector 4 to form a unit.

[0041] Conversely, only the cathode electrode 2B may have a support layer. In this case, the cathode electrode 2B and the second interconnector 3 are welded, and the first interconnector 4 and the anode electrode 2C are joined by contact paste or the like.

[0042] In the configuration of this embodiment described above, similarly to the configuration of the first embodiment, even if a blowhole or the like occurs near the first welded portion 6, leakage of the first reactive gas to the outside can be prevented.

[0043] It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical ideas described in the claims. [Explanation of symbols]

[0044] REFERENCE SIGNS LIST 1 power generation unit, 2 power generation cell, 3 second interconnector, 4 first interconnector, 5 second welded portion, 6 first welded portion, 7 joint portion, 8 first reactant gas flow path, 9 second reactant gas flow path

Claims

1. A fuel cell in which a plurality of power generation cells, each having a solid electrolyte plate, an anode electrode disposed on one surface of the solid electrolyte plate, and a cathode electrode disposed on the other surface of the solid electrolyte plate, are stacked in a thickness direction via a first interconnector and a second interconnector, the anode electrode and the cathode electrode each have a support layer formed of a metal porous body; the first interconnector has a corrugated plate shape having a plurality of first ribs that are parallel to each other and protrude toward a support layer of the anode electrode in the thickness direction and extend in a direction perpendicular to the thickness direction, and tops of the first ribs are welded to the support layer of the anode electrode to form a first reactant gas flow path between adjacent first ribs; the second interconnector has a corrugated plate shape having a plurality of second ribs that protrude toward a support layer side of the anode electrode in the thickness direction and extend in a direction perpendicular to the thickness direction and are parallel to each other; an opening of the first rib when the first interconnector is viewed from a side opposite to the support layer of the anode electrode is sealed by being joined to the second rib; A fuel cell, characterized in that another of the power generating cells is joined to a surface of the second interconnector opposite to the first interconnector.

2. 2. The fuel cell according to claim 1 , A fuel cell, wherein a communication hole is provided on the inclined surface of the first rib, the communication hole communicating a space between adjacent first ribs with a space inside the first rib.

3. The fuel cell according to claim 1, A fuel cell, wherein a communication hole is provided on the inclined surface of the second rib, the communication hole communicating the space between adjacent second ribs with the space inside the second rib.

4. The fuel cell according to claim 2 or 3, A cross section of the first rib perpendicular to the longitudinal direction of the first rib has a width that increases as the cross section moves away from the welded portion to the support layer, A cross section of the second rib perpendicular to the longitudinal direction has a width that increases as the cross section moves away from the joint portion with the first rib, The maximum width of the first rib is equal to or smaller than the minimum width of the second rib, A fuel cell, wherein an inclination angle of an inclined surface extending from the flat portion of the first rib toward the welded portion is smaller than an inclination angle of an inclined surface extending from the flat portion of the second rib toward the joint portion.

5. A method for manufacturing a fuel cell in which a plurality of power generation cells, each having a solid electrolyte plate, an anode electrode disposed on one surface of the solid electrolyte plate, and a cathode electrode disposed on the other surface of the solid electrolyte plate, are stacked in a thickness direction via a first interconnector and a second interconnector, forming a support layer made of a metal porous body on the anode electrode and the cathode electrode; the first interconnector is formed in a corrugated plate shape having a plurality of first ribs that protrude in the thickness direction toward a support layer of the anode electrode and extend in a direction perpendicular to the thickness direction and are parallel to each other; a first reactant gas flow passage is formed between adjacent first ribs by welding a top of the first rib to a support layer of the anode electrode; the second interconnector is formed in a corrugated plate shape having a plurality of second ribs that protrude in the thickness direction toward a support layer of the anode electrode and extend in a direction perpendicular to the thickness direction and are parallel to each other; an opening of the first rib when the first interconnector is viewed from a side opposite to the support layer of the anode electrode is sealed by joining the second rib; A method for manufacturing a fuel cell, comprising joining another of the power generating cells to a surface of the second interconnector opposite to the first interconnector.

6. The method for producing a fuel cell according to claim 5, The first interconnector and the second interconnector are joined by metallic solid phase diffusion.

7. The method for producing a fuel cell according to claim 5, The first interconnector and the second interconnector are joined by local heating caused by electrical current passing therethrough.

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