Fuel cell stack and fuel cell

Abstract

To provide a fuel cell stack and a fuel cell, which can be made compact.SOLUTION: A fuel cell stack according to an embodiment includes a plurality of single cells. The single cells each include a membrane electrode assembly, a first separator, a first gas passage, a second separator, a second gas passage, a cooling water passage, and a pair of seal portions. A third side of a cathode separator is located inside a first side of an anode separator. One seal portion abuts a first outer edge located outside a corresponding third side on a first separator facing surface. The other seal portion abuts the first outer edge located outside the corresponding third side on the first separator facing surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present embodiment relates to a fuel cell stack and a fuel cell. [Background technology]

[0002] A fuel cell is a power generation device that generates electricity by chemically reacting a fuel gas such as hydrogen with an oxidant gas such as air to convert the chemical energy of the fuel gas into electrical energy. Fuel cells are classified into various types based on the type of electrolyte. For example, solid polymer fuel cells, which use a solid polymer membrane as the electrolyte, have excellent low-temperature operation and high power density. For this reason, they are suitable for use as small cogeneration systems for ordinary households or as a power source for fuel cell vehicles, and the market size is expected to expand rapidly in the future.

[0003] A fuel cell includes a fuel cell stack made up of multiple stacked unit cells. Each unit cell is composed of a membrane electrode assembly (MEA) and two separators. The membrane electrode assembly has a configuration in which a fuel electrode and an oxidizer electrode are arranged to sandwich an electrolyte membrane. A fuel gas containing hydrogen gas supplied to the fuel electrode reacts with an oxidizer gas containing oxygen gas supplied to the oxidizer electrode to generate electricity.

[0004] One separator, also called the anode separator, has a fuel gas flow channel formed therein. A groove forming the fuel gas flow channel is formed on one surface of the anode separator, and the anode separator is bonded to the fuel electrode so that this groove faces the fuel electrode of the membrane electrode assembly. The other separator, also called the cathode separator, has an oxidant gas flow channel formed therein. A groove forming the oxidant gas flow channel is formed on one surface of the cathode separator. A groove forming a cooling water flow channel is formed on the other surface of the cathode separator, and grooves forming flow channels are formed on both surfaces of the cathode separator. The cathode separator is bonded to the anode separator so that the groove of the cooling water flow channel faces the anode separator. The groove of the oxidant gas flow channel faces the oxidant electrode of another adjacent unit cell.

[0005] When viewed in the stacking direction, a sealing member is disposed on the outside of the oxidant gas flow channel of the cathode separator. The sealing member prevents the oxidant gas flowing in the oxidant gas flow channel from mixing with the fuel gas flowing in the manifold. The sealing member also prevents the oxidant gas flowing in the oxidant gas flow channel from mixing with the cooling water flowing in the manifold.

[0006] As shown in Fig. 8, which will be described later, the sealing member abuts against the cathode separator. This can increase the thickness of the cathode separator. In this case, the thickness of the single cell increases, which can make it difficult to make the fuel cell stack compact. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5242189 Summary of the Invention [Problem to be solved by the invention]

[0008] The present embodiment has been made in consideration of these points, and aims to provide a fuel cell stack and a fuel cell that can be made compact. [Means for solving the problem]

[0009] A fuel cell stack according to an embodiment includes a plurality of stacked unit cells. Each unit cell includes a membrane electrode assembly, a first separator, a first gas flow path, a second separator, a second gas flow path, a cooling water flow path, and a pair of seals. The first separator includes a first electrode-opposing surface facing the membrane electrode assembly and a first separator-opposing surface located on the opposite side from the first electrode-opposing surface. The first gas flow path is provided on the first electrode-opposing surface. The second separator includes a second separator-opposing surface facing the first separator-opposing surface and a second electrode-opposing surface located on the opposite side from the second separator-opposing surface. The second gas flow path is provided on the second electrode-opposing surface. The seals abut against the membrane electrode assemblies of adjacent unit cells. The coolant flow path includes a flow path inlet and a flow path outlet provided on the first separator-opposing surface, and a flow path main body provided on the second separator-opposing surface, the flow path main body communicating with the flow path inlet and the flow path outlet. When viewed in the stacking direction, the first separator is formed in a rectangular shape and includes a pair of first sides and a pair of second sides. The inlet of the first gas flow path is located on one of the first sides, and the outlet of the first gas flow path is located on the other first side. When viewed in the stacking direction, the second separator is formed in a rectangular shape and includes a pair of third sides corresponding to the first sides and a pair of fourth sides corresponding to the second sides. The inlet of the second gas flow path is located on one of the fourth sides, and the outlet of the second gas flow path is located on the other fourth side. Each third side is located inward from the corresponding first side. The seal portion abuts against a first outer edge portion located outside the corresponding third side of the first separator-opposing surface, and covers the flow path inlet. The other seal portion abuts against a first outer edge portion located outside the corresponding third side of the first separator opposing surface, and covers the flow path outlet portion.

[0010] A fuel cell according to an embodiment includes the above-described fuel cell stack. [Effects of the Invention]

[0011] According to the embodiment, the fuel cell stack can be made compact. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing a fuel cell stack according to a first embodiment. [Figure 2] FIG. 2 is a plan view showing the anode separator and the fuel gas flow channel taken along the line AA in FIG. [Figure 3] FIG. 3 is a plan view showing the cathode separator and the oxidizing gas flow field taken along the line BB in FIG. [Figure 4] FIG. 4 is a plan view showing the cathode separator and the cooling water channel at the position indicated by the line CC in FIG. [Figure 5] FIG. 5 is an enlarged cross-sectional view showing the flow channel inlet and flow channel outlet of the cooling water flow channel shown in FIGS. [Figure 6] FIG. 6 is an enlarged plan view showing the flow channel inlet and flow channel outlet of the cooling water flow channel shown in FIG. [Figure 7] FIG. 7 is an exploded perspective view showing the unit cell shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view showing a unit cell of a typical fuel cell stack. [Figure 9] FIG. 9 is a plan view showing the fuel gas flow path in the unit cell according to the second embodiment, taken along the line AA in FIG. [Figure 10] FIG. 10 is a plan view showing the oxidant gas flow path in the unit cell according to the second embodiment, taken along the line BB in FIG. [Figure 11] FIG. 11 is a plan view showing the cooling water flow path in the unit cell according to the second embodiment, taken along the line CC in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a fuel cell stack and a fuel cell according to an embodiment will be described with reference to the drawings.

[0014] (First embodiment) First, a fuel cell stack and a fuel cell according to a first embodiment will be described with reference to FIGS.

[0015] As shown in FIGS. 1 to 4, the fuel cell 1 includes a fuel cell stack 2 including a plurality of stacked unit cells 10, and a plurality of manifolds 3 to 6 provided on the side of the fuel cell stack 2. More specifically, a cell stack is made up of the plurality of stacked unit cells 10. The cell stack is formed into a rectangular shape when viewed in the stacking direction. The stacking direction is the direction in which the unit cells 10 are stacked, and corresponds to the up-and-down direction in FIG. 1. The cell stack is clamped by a pair of clamping plates (not shown). An insulating plate and a current collector are interposed between the clamping plates and the cell stack, allowing the generated power of each unit cell 10 to be extracted. The manifold will be described later.

[0016] Next, a fuel cell stack 2 according to this embodiment will be described. As shown in Fig. 1, the fuel cell stack 2 includes a plurality of unit cells 10 stacked as described above. Each unit cell 10 includes a membrane electrode assembly 11, an anode separator 20, a fuel gas flow field 25, a cathode separator 30, an oxidant gas flow field 35, a pair of seal members 50, and a pair of partition plates 60.

[0017] As shown in FIG. 1, the membrane electrode assembly 11 includes a fuel electrode 12, an oxidizer electrode 13, and an electrolyte membrane 14 interposed between the fuel electrode 12 and the oxidizer electrode 13. The fuel electrode 12 is also referred to as an anode electrode, and a fuel gas containing hydrogen gas is supplied to the fuel electrode 12. The oxidizer electrode 13 is also referred to as a cathode electrode, and an oxidizer gas containing oxygen gas is supplied to the oxidizer electrode 13. The hydrogen gas and the oxygen gas react with each other to generate electricity. The electrolyte membrane 14 may be, for example, a solid polymer membrane.

[0018] The anode separator 20 is an example of a first separator. As shown in FIG. 1, the anode separator 20 includes a fuel electrode-facing surface 21 that faces the fuel electrode 12 of the membrane electrode assembly 11, and a first separator-facing surface 22 that is located on the opposite side of the fuel electrode-facing surface 21. The fuel electrode-facing surface 21 is an example of a first electrode-facing surface. As shown in FIG. 2, the anode separator 20 is formed in a rectangular shape when viewed in the stacking direction, and includes a pair of first sides 20a and a pair of second sides 20b. The anode separator 20 is bonded to the fuel electrode 12 to provide a sealing function. For example, the anode separator 20 and the fuel electrode 12 may be bonded together via an adhesive sheet (not shown).

[0019] The fuel gas flow channel 25 is an example of a first gas flow channel. As shown in FIG. 1, the fuel gas flow channel 25 is provided on the fuel electrode-facing surface 21 of the anode separator 20. The fuel gas flow channel 25 is composed of a plurality of grooves 26 formed in the fuel electrode-facing surface 21. As shown in FIG. 2, an inlet 25a of the fuel gas flow channel 25 is located on one first side 20a of the anode separator 20, and an outlet 25b of the fuel gas flow channel 25 is located on the other first side 20a. The grooves 26 of the fuel gas flow channel 25 shown in FIG. 2 are formed in a crank shape.

[0020] The cathode separator 30 is an example of a second separator. As shown in Fig. 1, the cathode separator 30 includes a second separator-facing surface 31 facing the first separator-facing surface 22 of the anode separator 20, and an oxidizer electrode-facing surface 32 located on the opposite side of the second separator-facing surface 31. The oxidizer electrode-facing surface 32 is an example of a second electrode-facing surface. As shown in Fig. 3, the cathode separator 30 is formed in a rectangular shape when viewed in the stacking direction, and includes a pair of third sides 30a corresponding to the pair of first sides 20a and a pair of fourth sides 30b corresponding to the pair of second sides 20b.

[0021] In this embodiment, when viewed in the stacking direction, each third side 30a is located more inward than the corresponding first side 20a. As a result, the portion of the first separator-opposing surface 22 of the anode separator 20 that is outward from the corresponding third side 30a is not covered by the cathode separator 30. In other words, the first separator-opposing surface 22 includes a pair of first outer edge portions 23 that are located outward from the corresponding third side 30a and are not covered by the cathode separator 30. The cathode separator 30 is bonded to the anode separator 20 to provide a sealing function. For example, the anode separator 20 and the cathode separator 30 may be bonded together via an adhesive sheet (not shown).

[0022] The oxidant gas flow field 35 is an example of a second gas flow field. As shown in FIG. 1, the oxidant gas flow field 35 is provided on the oxidant electrode-facing surface 32 of the cathode separator 30. The oxidant gas flow field 35 is composed of a plurality of grooves 36 formed in the oxidant electrode-facing surface 32. As shown in FIG. 3, an inlet 35a of the oxidant gas flow field 35 is located on one fourth side 30b of the cathode separator 30, and an outlet 35b of the oxidant gas flow field 35 is located on the other fourth side 30b. The grooves 36 of the oxidant gas flow field 35 shown in FIG. 3 are formed linearly.

[0023] As shown in FIGS. 2, 4, and 5, the coolant flow path 40 is provided on the first separator-opposing surface 22 of the anode separator 20 and the second separator-opposing surface 31 of the cathode separator 30. More specifically, the coolant flow path 40 includes a flow path inlet 41 and a flow path outlet 42 provided on the first separator-opposing surface 22, and a flow path main body 43 provided on the second separator-opposing surface 31. The flow path main body 43 communicates with the flow path inlet 41 and the flow path outlet 42 and is located between the flow path inlet 41 and the flow path outlet 42 in the flow direction of the coolant. The flow path main body 43 shown in FIG. 4 is composed of a plurality of grooves 44 formed on the second separator-opposing surface 31. The grooves 44 of the flow path main body 43 are formed in a serpentine shape.

[0024] As shown in FIGS. 5 and 6 , when viewed in the stacking direction, the flow path inlet portion 41 extends from one first side 20a of the anode separator 20 to cross the corresponding third side 30a of the cathode separator 30. The flow path inlet portion 41 extends from the first side 20a to a position where it overlaps with the inlet-side end 43a of the flow path main body 43. The flow path inlet portion 41 may extend from the same first side 20a as the inlet 25a of the fuel gas flow path 25. As shown in FIG. 2 , the flow path inlet portion 41 is located closer to the outlet 35b of the oxidant gas flow path 35 than the inlet 35a of the oxidant gas flow path 35. However, the flow path inlet portion 41 may also be located closer to the inlet 35a of the oxidant gas flow path 35 than the outlet 35b of the oxidant gas flow path 35.

[0025] As shown in FIGS. 5 and 6 , when viewed in the stacking direction, the flow path outlet 42 extends from the other first side 20a of the anode separator 20 to cross the corresponding third side 30a of the cathode separator 30. The flow path outlet 42 extends from the first side 20a to a position overlapping with the outlet-side end 43b of the flow path main body 43. The flow path outlet 42 may extend from the same first side 20a as the outlet 25b of the fuel gas flow path 25. As shown in FIG. 2 , the flow path outlet 42 is located closer to the inlet 35a of the oxidant gas flow path 35 than the outlet 35b of the oxidant gas flow path 35. However, when the flow path inlet 41 is located closer to the inlet 35a of the oxidant gas flow path 35, the flow path outlet 42 may be located closer to the outlet 35b of the oxidant gas flow path 35 than the inlet 35a of the oxidant gas flow path 35.

[0026] 6, the flow path inlet portion 41 and the flow path outlet portion 42 may extend from the first separator-facing surface 22 to the fuel electrode-facing surface 21. That is, the flow path inlet portion 41 and the flow path outlet portion 42 penetrate the anode separator 20 and are defined by the fuel electrode 12 adjacent to this anode separator 20 and a partition plate 60 described below. Note that the flow path inlet portion 41 and the flow path outlet portion 42 do not have to penetrate the anode separator 20 as long as they are formed on the first separator-facing surface 22.

[0027] As shown in FIGS. 5 and 6 , a straightening plate 45 may be provided at each of the flow path inlet 41 and the flow path outlet 42. The straightening plate 45 may extend from the first separator-facing surface 22 to the fuel electrode-facing surface 21, or may abut against the partition plate 60 and the fuel electrode 12. A plurality of straightening plates 45 may be provided at the flow path inlet 41. In this case, the number of flow paths defined by the straightening plates 45 may be equal to the number of grooves 44 in the flow path main body 43 formed in the cathode separator 30. Similarly, a plurality of straightening plates 45 may be provided at the flow path outlet 42. In this case, the number of flow paths defined by the straightening plates 45 may be equal to the number of grooves 44 in the flow path main body 43.

[0028] The manifolds will now be described. As shown in Figures 2 to 4, the fuel cell 1 according to this embodiment includes an anode inlet manifold 3, an anode outlet manifold 4, an oxidizer electrode inlet manifold 5, and an oxidizer electrode outlet manifold 6.

[0029] The anode inlet manifold 3 is attached to one side of the fuel cell stack 2. As shown in FIG. 2, this side includes a first side 20a of the anode separator 20, where the inlet 25a of the fuel gas flow channel 25 is located, and a corresponding third side 30a of the cathode separator 30. The anode inlet manifold 3 includes a fuel gas supply channel 7a that communicates with the inlet 25a of each fuel gas flow channel 25. Fuel gas is supplied to the fuel gas flow channel 25 from the fuel gas supply channel 7a.

[0030] The anode inlet manifold 3 according to this embodiment includes a cooling water supply passage 9a that communicates with the passage inlet 41 of each cooling water passage 40. As shown in Fig. 4, the cooling water is supplied from the cooling water supply passage 9a to the cooling water passage 40. The cooling water supply passage 9a is separated from the fuel gas supply passage 7a.

[0031] The anode outlet manifold 4 is attached to another side surface of the fuel cell stack 2. As shown in FIG. 2, this side surface is home to the first side 20a of the anode separator 20, where the outlets 25b of the fuel gas flow channels 25 are located, and the corresponding third side 30a of the cathode separator 30. The anode outlet manifold 4 includes a fuel gas discharge channel 7b that communicates with the outlets 25b of each fuel gas flow channel 25. The fuel gas is discharged from the fuel gas flow channels 25 to the fuel gas discharge channel 7b.

[0032] The anode outlet manifold 4 according to this embodiment includes a cooling water discharge flow path 9b that communicates with the flow path outlet portion 42 of the cooling water flow path 40. As shown in Fig. 4, the cooling water is discharged from the cooling water flow path 40 to the cooling water discharge flow path 9b. The cooling water discharge flow path 9b is separated from the fuel gas discharge flow path 7b.

[0033] The oxidant electrode inlet manifold 5 is attached to another side surface of the fuel cell stack 2. As shown in FIG. 3 , this side surface is home to the fourth side 30b of the cathode separator 30, where the inlet 35a of the oxidant gas channel 35 is located, and the corresponding second side 20b of the anode separator 20. The oxidant electrode inlet manifold 5 includes an oxidant gas supply channel 8a that communicates with the inlet 35a of each oxidant gas channel 35. The oxidant gas is supplied to the oxidant gas channel 35 from the oxidant gas supply channel 8a.

[0034] The oxidant electrode outlet manifold 6 is attached to another side surface of the fuel cell stack 2. As shown in FIG. 3, this side surface is home to the fourth side 30b of the cathode separator 30, where the outlets 35b of the oxidant gas channels 35 are located, and the corresponding second side 20b of the anode separator 20. The oxidant electrode outlet manifold 6 includes oxidant gas discharge channels 8b that communicate with the outlets 35b of the oxidant gas channels 35. The oxidant gas is discharged from the oxidant gas channels 35 to the oxidant gas discharge channels 8b.

[0035] Next, the seal portion 50 will be described.

[0036] 1, the sealing portion 50 abuts against the membrane electrode assembly 11 of another adjacent unit cell 10. The sealing portion 50 is a member that separates the oxidant gas flow channel 35 formed in the cathode separator 30 from the fuel gas supply flow channel 7a and the coolant supply flow channel 9a of the anode inlet manifold 3, and also separates the oxidant gas flow channel 35 from the fuel gas discharge flow channel 7b and the coolant discharge flow channel 9b of the anode outlet manifold 4.

[0037] 3 to 5, the seal portion 50 includes a first seal member 51 located outside the corresponding third side 30a of the cathode separator 30. The first seal member 51 abuts against the above-mentioned first outer edge portion 23 formed on the first separator-opposing surface 22 of the anode separator 20.

[0038] As shown in FIG. 5 , the first seal member 51 includes a main body seal portion 52 and a lip portion 53 extending upward from the main body seal portion 52. The main body seal portion 52 abuts against the first outer edge portion 23 of the first separator opposing surface 22 via a partition plate 60 (described later). As shown in FIGS. 4 and 5 , the main body seal portion 52 of one of the first seal members 51 covers the flow path inlet portion 41 of the coolant flow path 40 formed in the first separator opposing surface 22. The main body seal portion 52 of the other first seal member 51 covers the flow path outlet portion 42 of the coolant flow path 40 formed in the first separator opposing surface 22. The lip portion 53 of each first seal member 51 abuts against the oxidizer electrode 13 of the adjacent unit cell 10. When assembling the fuel cell stack 2, the first seal members 51 are clamped by a pair of clamping plates and pressed to perform their sealing function.

[0039] 3, 4, and 7, when viewed in the stacking direction, the first sealing member 51 extends linearly along the first side 20a of the anode separator 20 and the third side 30a of the cathode separator 30. The first sealing member 51 may extend from one second side 20b to the other second side 20b.

[0040] The seal portion 50 may be made of any elastic material that can ensure durability and sealing performance. For example, the seal portion 50 may be made of silicone rubber or EPDM.

[0041] As shown in FIGS. 6 and 7 , the partition plates 60 may be interposed between the corresponding first seal members 51 and the flow path inlet portions 41 or the flow path outlet portions 42 of the cooling water flow paths 40. The partition plates 60 abut against the first outer edge portions 23 of the first separator-opposing surface 22. As shown in FIGS. 4 and 6 , the partition plates 60 located on the inlet 25a side of the fuel gas flow path 25 cover the flow path inlet portions 41 of the cooling water flow path 40, preventing the first seal members 51 from entering the flow path inlet portions 41. Similarly, the partition plates 60 located on the outlet 25b side of the fuel gas flow path 25 cover the flow path outlet portions 42 of the cooling water flow path 40, preventing the first seal members 51 from entering the flow path outlet portions 42.

[0042] The partition plate 60 may be made of any material as long as it can prevent the seal portion 50 from entering the flow path inlet portion 41 or the flow path outlet portion 42. For example, the partition plate 60 may be made of a metal material such as stainless steel or titanium, or may be made of a resin material.

[0043] The partition plate 60 is adhered to the first outer edge portion 23 of the first separator-opposing surface 22 so as to have a sealing function. This allows the coolant flow path 40 formed in the cathode separator 30 to be separated from the fuel gas flow path 25. For example, the partition plate 60 and the first separator-opposing surface 22 may be adhered to each other with an adhesive sheet (not shown) interposed therebetween.

[0044] 7, the above-described straightening plate 45 may be bonded to the partition plate 60. More specifically, the straightening plate 45 located inside the flow path inlet portion 41 may be bonded to the partition plate 60 corresponding to the flow path inlet portion 41 of the cooling water flow path 40. The straightening plate 45 located inside the flow path outlet portion 42 may be bonded to the partition plate 60 corresponding to the flow path outlet portion 42 of the cooling water flow path 40. The straightening plate 45 may be bonded to the partition plate 60 in advance before the partition plate 60 is bonded to the first separator opposing surface 22.

[0045] 1, a pair of accommodation portions 33 for accommodating corresponding partition plates 60 may be formed on the second separator-opposing surface 31 of the cathode separator 30. The accommodation portions 33 according to this embodiment extend inward from the corresponding third side 30a. The surface of the partition plate 60 accommodated in the accommodation portions 33 facing the anode separator 20 and the second separator-opposing surface 31 may be located on the same plane. The channel main body 43 of the coolant channel 40 may be connected to the accommodation portions 33.

[0046] Here, a unit cell 10 of a typical fuel cell stack 2 will be described with reference to FIG.

[0047] The unit cell 10 shown in FIG. 8 includes a seal member 70 for separating the oxidant gas flow path 35 formed in the cathode separator 30 from the fuel gas flow path 25 in the manifold. The seal member 70 is housed in a housing 71 formed in the oxidant electrode-facing surface 32 of the cathode separator 30. Grooves 44 for the coolant water flow path 40 are formed in the second separator-facing surface 31 of the cathode separator 30. When viewed in the stacking direction, the seal member 70 and the coolant water flow path 40 overlap. The depth d1 of the housing 71 is deeper than the depth d2 of the grooves 36 of the oxidant gas flow path 35. Therefore, the thickness t2 of the cathode separator 30 is determined by taking into account the depth d3 of the coolant water flow path 40, the depth d1 of the housing 71, and the thickness t1 between the coolant water flow path 40 and the housing 71. This results in a problem of an increased thickness t2 of the cathode separator 30.

[0048] In contrast, in this embodiment, when viewed in the stacking direction, the third side 30a of the cathode separator 30 is located more inward than the corresponding first side 20a of the anode separator 20. The first seal member 51 of the seal unit 50 abuts against the first outer edge portion 23 of the first separator-opposing surface 22 of the anode separator 20, and this first seal member 51 covers the flow path inlet portion 41 of the coolant flow path 40. The first seal member 51 also abuts against the oxidizer electrode 13 of another adjacent unit cell 10. As a result, the first seal member 51 located on the inlet 25a side of the fuel gas flow path 25 can separate the oxidizer gas flow path 35 formed in the cathode separator 30 from the fuel gas supply flow path 7a and the coolant supply flow path 9a formed in the anode inlet manifold 3. The first sealing member 51 located on the outlet 25b side of the fuel gas flow path 25 separates the oxidant gas flow path 35 formed in the cathode separator 30 from the fuel gas discharge flow path 7b and the cooling water discharge flow path 9b formed in the fuel electrode outlet manifold 4.

[0049] Furthermore, because the first seal member 51 abuts against the first outer edge portion 23 of the first separator-opposing surface 22 of the anode separator 20, it is not necessary to provide the cathode separator 30 with a storage portion 71 for storing the first seal member 51. This eliminates the need to consider the depth d1 (see FIG. 8 ) of the storage portion 71, which is deeper than the depth d2 of the grooves 36 of the oxidant gas flow field 35, when determining the thickness of the cathode separator 30. In this case, the thickness t2 of the cathode separator 30 is determined taking into account the depth d2 of the oxidant gas flow field 35, the depth d3 of the coolant flow field 40, and the thickness t3 between the oxidant gas flow field 35 and the coolant flow field 40. This allows the thickness t2 of the cathode separator 30 to be reduced.

[0050] As described above, according to this embodiment, the third side 30a of the cathode separator 30 is located more inward than the corresponding first side 20a of the anode separator 20. The seal portion 50 abuts against the first outer edge portion 23 of the first separator facing surface 22, which is located more outward than the corresponding third side 30a. This allows the oxidant gas flow channel 35 formed in the cathode separator 30 to be separated from the fuel gas supply flow channel 7a of the anode inlet manifold 3 and the fuel gas discharge flow channel 7b of the anode outlet manifold 4. One seal portion 50 covers the flow channel inlet portion 41 of the cooling water flow channel 40, and the other seal portion 50 covers the flow channel outlet portion 42 of the cooling water flow channel 40. This allows the oxidant gas flow channel 35 formed in the cathode separator 30 to be separated from the cooling water supply flow channel 9a of the anode inlet manifold 3 and the cooling water discharge flow channel 9b of the anode outlet manifold 4. As described above, this also allows the thickness of the cathode separator 30 to be reduced. Therefore, the single cell 10 can be made thinner, and the fuel cell stack 2 can be made more compact.

[0051] Furthermore, according to the present embodiment, a partition plate 60 is interposed between the corresponding first seal member 51 and the flow path inlet portion 41 of the cooling water flow path 40, and a partition plate 60 is interposed between the corresponding first seal member 51 and the flow path outlet portion 42 of the cooling water flow path 40. In this case, a flat surface can be formed on the flow path inlet portion 41, and a flat surface can be formed on the flow path outlet portion 42. This makes it possible to prevent the first seal member 51 from entering the flow path inlet portion 41 or the flow path outlet portion 42, thereby improving the sealing function of the first seal member 51.

[0052] Furthermore, according to this embodiment, the partition plate 60 is adhered to the first separator opposing surface 22 so as to have a sealing function. This makes it possible to separate the cooling water flow path 40 formed in the cathode separator 30 from the fuel gas flow path 25. This makes it possible to prevent the cooling water and the fuel gas from mixing.

[0053] Furthermore, according to the present embodiment, the flow path inlet portion 41 and the flow path outlet portion 42 of the coolant flow path 40 extend from the first separator-opposing surface 22 to the fuel electrode-opposing surface 21. This allows the flow path inlet portion 41 and the flow path outlet portion 42 to penetrate the anode separator 20, thereby increasing the flow path cross-sectional area of ​​the flow path inlet portion 41 and the flow path outlet portion 42. This reduces the flow path resistance of the coolant flow path 40 and suppresses the occurrence of loss in the flow of the coolant. Furthermore, by having the flow path inlet portion 41 and the flow path outlet portion 42 penetrate the anode separator 20 in this manner, the flow path cross-sectional area of ​​the coolant flow path 40 can be increased without increasing the thickness of the anode separator 20. This allows the flow path cross-sectional area of ​​the coolant flow path 40 to be secured and the thickness of the anode separator 20 to be reduced.

[0054] According to the present embodiment, the flow straightening plates 45 are provided at the flow inlet 41 and the flow outlet 42 of the cooling water flow path 40, respectively. This straightens the flow of the cooling water, thereby suppressing loss of the cooling water flow. The flow straightening plates 45 also support the partition plate 60. This further prevents the first seal member 51 from entering the flow inlet 41 or the flow outlet 42, thereby enhancing the sealing function of the first seal member 51 and ensuring the flow cross-sectional area of ​​the cooling water flow path 40. The flow straightening plates 45 also support the membrane electrode assemblies 11. This prevents the membrane electrode assemblies 11 from entering the flow inlet 41 or the flow outlet 42, thereby ensuring the flow cross-sectional area of ​​the cooling water flow path 40.

[0055] Furthermore, according to this embodiment, when viewed in the stacking direction, the flow path inlet portion 41 extends from one first side 20a of the anode separator 20 across the corresponding third side 30a, and the flow path outlet portion 42 extends from the other first side 20a of the anode separator 20 across the corresponding third side 30a. When viewed in the stacking direction, the first seal member 51 extends along the first side 20a and the third side 30a of the cathode separator 30. This simplifies the shape of the first seal member 51 covering the flow path inlet portion 41 or the flow path outlet portion 42, and also simplifies the sealing structure of the flow path inlet portion 41 and the flow path outlet portion 42. This improves the sealing function of the first seal member 51.

[0056] In the above-described present embodiment, an example has been described in which the anode separator 20 is an example of the first separator, and the cathode separator 30 is an example of the second separator. However, the present embodiment is not limited to this. An example of the first separator may be the cathode separator 30, and an example of the second separator may be the anode separator 20. That is, the cathode separator 30 may be bonded to the oxidizer electrode 13 of the membrane electrode assembly 11, and the anode separator 20 may be bonded to this cathode separator 30. In this case, the flow path inlet 41 and the flow path outlet 42 of the coolant flow path 40 may be formed on the second separator-facing surface 31 of the cathode separator 30, and the flow path main body 43 may be formed on the first separator-facing surface 22 of the anode separator 20. The seal portion 50 abuts against the outer edge of the second separator-opposing surface 31 of the cathode separator 30, and may also abut against the fuel electrode 12 of another adjacent unit cell 10.

[0057] (Second embodiment) Next, a fuel cell stack and a fuel cell according to a second embodiment will be described with reference to FIGS.

[0058] The second embodiment shown in FIGS. 9 to 11 is different from the first embodiment shown in FIGS. 1 to 8 mainly in that the flow path inlet of the cooling water flow path is located on one of the second sides of the anode separator and the flow path outlet is located on the other of the second sides of the anode separator. In other respects, the configuration is the same as that of the first embodiment shown in FIGS.

[0059] 9, in the present embodiment, an inlet 25a of the fuel gas flow field 25 is located on one first side 20a of the anode separator 20, and an outlet 25b of the fuel gas flow field 25 is located on the other first side 20a. The fuel gas flow field 25 shown in FIG. 9 is formed linearly.

[0060] In this embodiment, when viewed in the stacking direction, each fourth side 30b includes an outer portion 30c overlapping the corresponding second side 20b and an inner portion 30d located more inward than the corresponding second side 20b. As a result, the portion of the first separator-opposing surface 22 of the anode separator 20 that is outward from the inner portion 30d of the corresponding fourth side 30b is not covered by the cathode separator 30. In other words, the first separator-opposing surface 22 includes the above-mentioned pair of first outer edge portions 23 located more outward than the corresponding third side 30a and a pair of second outer edge portions 24 located more outward than the corresponding fourth side 30b. When viewed in the stacking direction, the first outer edge portions 23 and the second outer edge portions 24 are formed in an L-shape as a whole.

[0061] Each inner portion 30d is connected to the corresponding third side 30a. That is, the inner portion 30d of the fourth side 30b corresponding to the inlet 35a of the oxidant gas flow field 35 is connected to the third side 30a corresponding to the outlet 25b of the fuel gas flow field 25. The inner portion 30d of the fourth side 30b corresponding to the outlet 35b of the oxidant gas flow field 35 is connected to the third side 30a corresponding to the inlet 25a of the fuel gas flow field 25.

[0062] 10, the inlet 35a of the oxidant gas flow field 35 is located on an outer side 30c of one fourth side 30b of the cathode separator 30, and the outlet 35b of the oxidant gas flow field 35 is located on an outer side 30c of the other fourth side 30b. The groove 36 of the oxidant gas flow field 35 shown in FIG. 3 is formed in a crank shape.

[0063] As shown in FIG. 11 , the flow path inlet portion 41 of the coolant flow path 40 extends from one second side 20b of the anode separator 20 across the inner portion 30d of the corresponding fourth side 30b. The flow path inlet portion 41 extends from the inner portion 30d to a position where it overlaps with the inlet end portion 43a of the flow path main body 43. The flow path inlet portion 41 may extend from the second side 20b corresponding to the outlet 35b of the oxidant gas flow path 35. The flow path inlet portion 41 shown in FIG. 11 is located closer to the inlet 25a of the fuel gas flow path 25 than the outlet 25b of the fuel gas flow path 25. However, the flow path inlet portion 41 may also be located closer to the outlet 25b of the fuel gas flow path 25 than the inlet 25a of the fuel gas flow path 25.

[0064] The flow path outlet 42 of the coolant flow path 40 extends from the other second side 20b of the anode separator 20 so as to cross the inner portion 30d of the corresponding fourth side 30b. The flow path outlet 42 extends from the inner portion 30d to a position overlapping with the outlet-side end 43b of the flow path main body 43. The flow path outlet 42 may extend from the second side 20b corresponding to the inlet 35a of the oxidant gas flow path 35. The flow path outlet 42 shown in FIG. 11 is located closer to the outlet 25b of the fuel gas flow path 25 than the inlet 25a of the fuel gas flow path 25. However, when the flow path inlet 41 is located closer to the outlet 25b of the fuel gas flow path 25, the flow path outlet 42 may be located closer to the inlet 25a of the fuel gas flow path 25 than the outlet 25b of the fuel gas flow path 25. The grooves 44 of the flow path main body 43 of the coolant flow path 40 shown in FIG. 11 are formed in a serpentine shape.

[0065] The anode inlet manifold 3 according to this embodiment does not include a cooling water supply channel 9a. The oxidizer electrode outlet manifold 6 includes a cooling water supply channel 9a. The cooling water supply channel 9a is separated from the oxidizer gas discharge channel 8b. Similarly, the anode outlet manifold 4 does not include a cooling water discharge channel 9b. The oxidizer electrode inlet manifold 5 includes a cooling water discharge channel 9b. The cooling water discharge channel 9b is separated from the oxidizer gas supply channel 8a.

[0066] The sealing portion 50 according to this embodiment separates the oxidant gas flow path 35 formed in the cathode separator 30 from the fuel gas supply flow path 7a of the fuel electrode inlet manifold 3 and the oxidant gas supply flow path 8a of the oxidant electrode inlet manifold 5, and also separates it from the fuel gas discharge flow path 7b of the fuel electrode outlet manifold 4 and the oxidant gas discharge flow path 8b of the oxidant electrode outlet manifold 6.

[0067] The seal portion 50 according to the present embodiment includes the above-described first seal member 51 and second seal member 54. In the present embodiment, the partition plate 60 is not interposed between the first seal member 51 and the first separator-opposing surface 22, and therefore the first seal member 51 directly contacts the first separator-opposing surface 22.

[0068] Although not shown, the second seal member 54 includes a main body seal portion 52 and a lip portion 53, similar to the first seal member 51. As shown in FIGS. 10 and 11 , the second seal member 54 is located outward from the inner portion 30d of the corresponding fourth side 30b of the first separator-opposing surface 22. The second seal member 54 abuts against the second outer edge portion 24 formed on the first separator-opposing surface 22 of the anode separator 20 via a partition plate 60. The main body seal portion 52 of one second seal member 54 covers the flow path inlet portion 41 of the coolant flow path 40 formed on the first separator-opposing surface 22. The main body seal portion 52 of the other second seal member 54 covers the flow path outlet portion 42 of the coolant flow path 40 formed on the first separator-opposing surface 22.

[0069] 10 and 11 , when viewed in the stacking direction, the second seal member 54 extends linearly along the second side 20b of the anode separator 20 and the inner portion 30d of the fourth side 40b of the cathode separator 30. The seal unit 50, which is made up of the first seal member 51 and the second seal member 54, is arranged in an L-shape as a whole. The first seal member 51 and the second seal member 54 may be formed separately, or may be formed integrally as an L-shaped seal member.

[0070] 11 , the partition plate 60 according to the present embodiment may be interposed between the corresponding second seal member 54 and the flow path inlet portion 41 or the flow path outlet portion 42 of the coolant flow path 40. The partition plate 60 abuts against the second outer edge portion 24 of the first separator-opposing surface 22. As shown in FIG. 11 , the partition plate 60 located on the inlet 35a side of the oxidant gas flow path 35 covers the flow path outlet portion 42 of the coolant flow path 40, preventing the second seal member 54 from entering the flow path outlet portion 42. Similarly, the partition plate 60 located on the outlet 35b side of the oxidant gas flow path 35 covers the flow path inlet portion 41 of the coolant flow path 40, preventing the second seal member 54 from entering the flow path inlet portion 41.

[0071] The partition plate 60 is bonded to the second outer edge portion 24 of the first separator opposing surface 22 so as to have a sealing function. This allows the cooling water flow path 40 formed in the cathode separator 30 to be separated from the fuel gas flow path 25.

[0072] The storage portion 33 formed on the second separator facing surface 31 of the cathode separator 30 may extend inward from the inner portion 30d of the corresponding fourth side 30b. In this embodiment, the storage portion 33 does not have to be formed on the third side 30a of the cathode separator 30.

[0073] As described above, according to this embodiment, the third side 30a of the cathode separator 30 is located more inward than the corresponding first side 20a of the anode separator 20. The first seal member 51 of the seal unit 50 abuts against a portion of the first separator-opposing surface 22 that is more outward than the corresponding third side 30a. This allows the oxidant gas flow channel 35 formed in the cathode separator 30 to be separated from the fuel gas supply flow channel 7a of the anode inlet manifold 3 and the fuel gas discharge flow channel 7b of the anode outlet manifold 4. The second seal member 54 of one seal unit 50 covers the flow channel inlet 41 of the coolant flow channel 40, and the second seal member 54 of the other seal unit 50 covers the flow channel outlet 42 of the coolant flow channel 40. This allows the oxidant gas flow channel 35 formed in the cathode separator 30 to be separated from the coolant discharge flow channel 9b of the anode inlet manifold 5 and the coolant supply flow channel 9a of the anode outlet manifold 6. This also allows the thickness of the cathode separator 30 to be reduced, which in turn allows the single cell 10 to be made thinner, and the fuel cell stack 2 to be made more compact.

[0074] Furthermore, according to this embodiment, when viewed in the stacking direction, the flow path inlet portion 41 extends from one second side 20b of the anode separator 20 across the inner portion 30d of the corresponding fourth side 30b, and the flow path outlet portion 42 extends from the other second side 20b of the anode separator 20 across the inner portion 30d of the corresponding fourth side 30b. When viewed in the stacking direction, the second seal member 54 extends along the second side 20b and the inner portion 30d of the fourth side 30b of the cathode separator 30. This simplifies the shape of the second seal member 54 covering the flow path inlet portion 41 or the flow path outlet portion 42, and also simplifies the sealing structure of the flow path inlet portion 41 and the flow path outlet portion 42. This improves the sealing function of the second seal member 54.

[0075] According to the embodiment described above, the fuel cell stack can be made compact.

[0076] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, it is of course possible to combine parts of these embodiments as appropriate within the spirit of the invention. [Explanation of symbols]

[0077] 1: fuel cell, 2: fuel cell stack, 10: single cell, 11: membrane electrode assembly, 20: anode separator, 20a: first side, 20b: second side, 21: fuel electrode facing surface, 22: first separator facing surface, 23: first outer edge, 24: second outer edge, 25: fuel gas flow path, 25a: inlet, 25b: outlet, 30: cathode separator, 30a: third side, 30b: Fourth side, 30c: outer portion, 30d: inner portion, 31: second separator facing surface, 32: oxidizer electrode facing surface, 35: oxidizer gas flow path, 35a: inlet, 35b: outlet, 40: cooling water flow path, 41: flow path inlet portion, 42: flow path outlet portion, 43: flow path main body portion, 45: current plate, 50: seal portion, 51: first seal member, 54: second seal member, 60: partition plate, D: stacking direction

Claims

1. The battery includes a plurality of stacked unit cells, The single cell is a membrane electrode assembly; a first separator including a first electrode facing surface facing the membrane electrode assembly and a first separator facing surface located on the opposite side to the first electrode facing surface; a first gas flow path provided on the first electrode facing surface; a second separator including a second separator-opposing surface facing the first separator-opposing surface and a second electrode-opposing surface located on the opposite side to the second separator-opposing surface; a second gas flow path provided on the second electrode facing surface; a cooling water flow path; a pair of seal portions that abut on the membrane electrode assembly of another adjacent unit cell, the coolant flow path includes a flow path inlet portion and a flow path outlet portion provided on the first separator-opposing surface, and a flow path main portion provided on the second separator-opposing surface, the flow path main portion communicating with the flow path inlet portion and the flow path outlet portion, When viewed in the stacking direction, the first separator is formed in a rectangular shape and includes a pair of first sides and a pair of second sides, an inlet of the first gas flow path is located on one of the first sides, and an outlet of the first gas flow path is located on the other first side; When viewed in the stacking direction, the second separator is formed in a rectangular shape and includes a pair of third sides corresponding to the first sides and a pair of fourth sides corresponding to the second sides, an inlet of the second gas flow path is located on one of the fourth sides, and an outlet of the second gas flow path is located on the other of the fourth sides; Each of the third sides is located more inward than the corresponding first side, the sealing portion abuts against a first outer edge portion of the first separator-opposing surface that is positioned outside the corresponding third side, and covers the flow path inlet portion; the other sealing portion abuts on a first outer edge portion of the first separator-opposing surface that is located outside the corresponding third side, and covers the flow path outlet portion. Fuel cell stack.

2. Further provided with a pair of partition plates, one of the partition plates is interposed between the corresponding seal portion and the flow path inlet portion of the cooling water flow path, The other partition plate is interposed between the corresponding seal portion and the flow path outlet portion of the cooling water flow path. The fuel cell stack of claim 1 .

3. The partition plate is adhered to the surface facing the first separator so as to have a sealing function. The fuel cell stack according to claim 2 .

4. the flow path inlet portion and the flow path outlet portion extend from the first separator-opposing surface to the first electrode-opposing surface.

3. The fuel cell stack according to claim 1 or 2.

5. A flow straightening plate is provided at each of the flow path inlet and the flow path outlet. The fuel cell stack according to claim 4 .

6. the flow path inlet portion of the cooling water flow path extends from one of the first sides to cross the corresponding third side, the flow path outlet portion of the cooling water flow path extends from the other first side to cross the corresponding third side, The sealing portion includes a first sealing member extending along the first side and the third side.

3. The fuel cell stack according to claim 1 or 2.

7. the fourth side includes an outer portion overlapping the corresponding second side when viewed in the stacking direction, and an inner portion located more inward than the corresponding second side, the flow path inlet portion of the cooling water flow path extends from one of the second sides to cross the corresponding inner portion, the flow path outlet portion of the cooling water flow path extends from the other second side to cross the corresponding inner portion, the seal portion includes a first seal member extending along the first side and the third side, and a second seal member abutting on a second outer edge portion of the first separator-opposing surface that is located outside the corresponding inner side portion and extending along the second side and the fourth side.

3. The fuel cell stack according to claim 1 or 2.

8. A fuel cell comprising the fuel cell stack according to claim 1 or 2.

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