Fuel cell

Abstract

To provide a fuel cell which has good gas diffusion property even when a porous material is used in a gas flow path, and with which it is possible to suppress pressure losses as well.SOLUTION: Provided is a fuel cell in which a plurality of power generation unit cells are stacked one on top of anther, each of which is constituted by including a membrane assembly, an anode separator which is stacked on one side of the membrane assembly, and a cathode separator which is stacked on the other side of the membrane assembly. The anode separator of one power generation unit cell and the cathode separator of the other power generation unit cell adjacent to the one power generation unit cell are stacked one on top of another, the cathode separator including a porous material which an oxidation gas flows into and a flow path expanding member, the flow path expanding member having a gas flow change expanding part by the porous material that expands the flow path, the gas flow path expanding part having a wall part inclined or orthogonal to a direction in which the oxidation gas flows.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to fuel cells. [Background technology]

[0002] Patent Document 1 discloses a fuel cell that uses a metal porous body as a gas flow path on the cathode side. Patent Document 2 discloses that the cathode gas flow path of the cell constituting the fuel cell is composed of a first expanded metal arranged on the gas inlet side and a second expanded metal arranged on the downstream side. The first expanded metal has a mesh arranged in a straight line, and the gas flowing on the gas diffusion layer side and the gas flowing on the separator side are separated. Patent Document 3 discloses that a plurality of minute grooves are formed on the opposing surfaces of the separators so as to extend in a direction intersecting the flow direction of the oxidizing gas flowing through the cathode-side porous flow passage. Patent Document 4 discloses that in a fuel cell, a first porous body is disposed between a first metal separator and a membrane electrode assembly. A first oxidant gas flow path extending in a wavy manner and through which an oxidant gas flows is formed in the first porous body. A second oxidant gas flow path extending in a straight manner and through which a reactant gas flows is formed in the first metal separator. The first oxidant gas flow path penetrates the first porous body in the thickness direction of the first porous body and communicates with the second oxidant gas flow path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-283196 A [Patent Document 2] JP 2012-226981 A [Patent Document 3] JP 2009-252426 A [Patent Document 4] JP 2020-057548 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a porous body is used for the gas flow path in the cathode, a flat plate is placed on the opposite side of the porous body to the side in contact with the gas diffusion layer in order to fully utilize the performance. However, there are problems with metal porous bodies, such as insufficient gas diffusivity and high pressure loss in the flow path.

[0005] In view of the above problems, an object of the present disclosure is to provide a fuel cell that has good gas diffusibility and is capable of suppressing pressure loss even when a porous body is used in the gas flow passages. [Means for solving the problem]

[0006] The present application relates to a fuel cell in which a power generation unit cell is formed having a membrane assembly, an anode separator stacked on one side of the membrane assembly, and a cathode separator stacked on the other side of the membrane assembly, and in which a plurality of power generation unit cells are stacked, the fuel cell being formed by stacking the anode separator of one power generation unit cell and the cathode separator of another power generation unit cell adjacent to the one power generation unit cell, the cathode separator having a porous body through which an oxidizing gas flows, and a flow path expansion member, the flow path expansion member having a gas flow path expansion portion that expands the flow path formed by the porous body, and the gas flow path expansion portion having a wall portion inclined or perpendicular to the flow direction of the oxidizing gas.

[0007] In the above fuel cell, the enlarged gas flow passage portion may be a groove.

[0008] In the fuel cell, the grooves may extend in a wavy shape.

[0009] The fuel cell may further include a cooling water passage expansion portion between adjacent gas passage expansion portions, which expands the cooling water passage of the anode separator. Effect of the Invention

[0010] According to the present disclosure, a fuel cell can be provided that has good gas diffusibility and is capable of suppressing pressure loss even when a porous body is used in the gas flow passages. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a fuel cell 1. As shown in FIG. [Diagram 2] FIG. 2 is a plan view of the power generating unit cell 10. As shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view of the power generating section 11, illustrating its layer structure. [Figure 4] FIG. 4 is an external perspective view illustrating the configuration of the cathode separator 20. As shown in FIG. [Diagram 5] FIG. 5 is a cross-sectional view illustrating the configuration of the cathode separator 20. As shown in FIG. [Figure 6] FIG. 6 is a diagram showing an example of the porous body 21. As shown in FIG. [Figure 7] FIG. 7 is a diagram showing an example in which the grooves 22a and 22c have a semi-elliptical shape. [Figure 8] FIG. 8 is a diagram illustrating the configuration of a flow path expansion member 22'. [Figure 9] FIG. 9 is another view for explaining the configuration of the flow path expansion member 22'. [Figure 10] FIG. 10 is an external perspective view illustrating the form of the flow path expansion member 122. As shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view illustrating the configuration of the flow path expansion member 122. As shown in FIG. [Figure 12] FIG. 12 is an external perspective view showing a part of the anode separator 17. As shown in FIG. [Figure 13] FIG. 13 is an external perspective view showing the stacked cathode separator 20 and anode separator 17 of adjacent power generating unit cells 10. As shown in FIG. [Figure 14] FIG. 14 is a cross-sectional view of FIG. [Figure 15] FIG. 15 is another cross-sectional view of FIG. [Figure 16] FIG. 16 is a diagram illustrating the flows of oxidizing gas and cooling water. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1.Fuel cell A fuel cell is a member in which a plurality of power generating unit cells (approximately 50 to 400 cells) are stacked, and current is collected from the plurality of power generating unit cells. An outline of the configuration is shown in Fig. 1. The fuel cell 1 includes a stack case 2, an end plate 3, a plurality of power generating unit cells 10, a current collecting plate 4, and a biasing member 5.

[0013] The stack case 2 is a housing that houses a plurality of stacked power generating unit cells 10, current collecting plates 4, and biasing members 5. In this embodiment, the stack case 2 is a rectangular cylinder with one end open and the other end closed, and a plate-like piece protrudes along the edge of the opening to the opposite side to the opening, forming a flange 2a.

[0014] The end plate 3 is a plate-shaped member that closes the opening of the stack case 2. The end plate 3 is disposed and fixed to the stack case 2 with bolts, nuts, etc. so as to cover the overlapping portion with the flange 2a of the stack case 2.

[0015] The configuration of the power generating unit cell 10 will be described in detail later. In the fuel cell 1, a plurality of power generating unit cells 10 are stacked.

[0016] The current collector 4 is a member that collects current from the stacked power generating unit cells 10. Therefore, the current collector 4 is disposed at each end of the stack of power generating unit cells 10, one of which serves as a positive electrode and the other as a negative electrode. A terminal (not shown) is connected to this current collector 4, and the current collector 4 is configured to be electrically connected to the outside.

[0017] The biasing member 5 is housed inside the stack case 2 and applies a pressing force in the stacking direction to the stack of power generating unit cells 10. An example of the biasing member is a disc spring.

[0018] 2.Power generation unit cell 2 and 3 are diagrams illustrating a power generating unit cell 10 according to one embodiment. The power generating unit cell 10 is a unit element for generating electricity by supplying hydrogen and oxygen (air), and the fuel cell 1 is constituted by stacking a plurality of power generating unit cells 10 as described above. Figure 2 is a plan view of the power generating unit cell 10, and Figure 2 is a diagram explaining the layer structure of the power generating section 11 of the power generating unit cell 10 in a cross section along AA, focusing on two of the stacked power generating unit cells 10.

[0019] The power generating section 11 is a section that contributes to power generation, and as can be seen from FIG. 3, is formed by laminating a plurality of layers. In the power generation section 11 of the power generation unit cell 10, one side of the electrolyte membrane 12 is a cathode (oxygen supply side) and the other side is an anode (hydrogen supply side). The cathode has a cathode catalyst layer 13, a cathode gas diffusion layer 14, and a cathode separator 20 laminated in this order from the electrolyte membrane 12 side. On the other hand, the anode has an anode catalyst layer 15, an anode gas diffusion layer 16, and an anode separator 17 laminated in this order from the electrolyte membrane 12 side. The laminate of the electrolyte membrane 12, the cathode catalyst layer 13, the cathode gas diffusion layer 14, the anode catalyst layer 15, and the anode gas diffusion layer 16 may be called a membrane assembly. The thickness of the membrane assembly is typically about 0.4 mm, and the thickness of the power generation unit cell 10 in the power generation section 11 is typically about 1.3 mm.

[0020] 2.1. Electrolyte membrane The electrolyte membrane 12 is a solid polymer thin film that exhibits good proton conductivity in a wet state. For example, it is made of a fluorine-based ion exchange membrane, and a carbon-fluorine-based polymer can be used, specifically, a perfluoroalkylsulfonic acid-based polymer (Nafion (registered trademark)) can be mentioned. The thickness of the electrolyte membrane 12 is not particularly limited, but is 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less.

[0021] 2.2. Cathode catalyst layer The cathode catalyst layer 13 is a layer containing a catalyst metal supported on a carrier. For example, the catalyst metal may be Pt, Pd, Rh, or an alloy containing these. The carrier may be a carbon carrier, more specifically, carbon particles made of glassy carbon, carbon black, activated carbon, coke, natural graphite, artificial graphite, or the like.

[0022] 2.3. Anode catalyst layer The anode catalyst layer 15 is also a layer containing a catalyst metal in a form in which the catalyst metal is supported on a carrier, similar to the cathode catalyst layer 13. Examples of the catalyst metal include Pt, Pd, Rh, and alloys containing these. Examples of the carrier include carbon carriers, more specifically carbon particles made of glassy carbon, carbon black, activated carbon, coke, natural graphite, artificial graphite, and the like.

[0023] 2.4. Cathode gas diffusion layer The cathode gas diffusion layer 14 can be made of, for example, a conductive porous body. More specific examples include carbon porous bodies (carbon paper, carbon cloth, glassy carbon, etc.), metal porous bodies (metal mesh, metal foam), etc. The cathode gas diffusion layer may be provided with an MPL (microporous layer) as needed. The MPL is a thin coating applied to the cathode catalyst layer 13 side of the cathode gas diffusion layer 14. The MPL has water repellency or hydrophilicity as needed and functions to adjust moisture. A typical MPL is one whose main components are a water repellent resin such as polytetrafluoroethylene (PTFE) and a conductive material such as carbon black.

[0024] 2.5. Anode gas diffusion layer The anode diffusion layer 16 can be made of, for example, a conductive porous body. More specific examples include carbon porous bodies (carbon paper, carbon cloth, glassy carbon, etc.) and metal porous bodies (metal mesh, metal foam).

[0025] 2.6. Cathode separator The cathode separator 20 is a member that supplies oxidizing gas (air in this embodiment) to the cathode gas diffusion layer 14. Fig. 4 shows a perspective view of a part of the power generation section 11 of the cathode separator 20 according to one embodiment. Fig. 5 shows a cross-sectional view of the cathode separator 20 taken along line BB in Fig. 4. As can be seen from Figs. 4 and 5, the cathode separator 20 has a porous body 21 and a flow path expansion member 22.

[0026] 2.6.1.Porous bodies The porous body 21 is a member provided with a countless number of holes through which gas can pass. There are no particular limitations on the specific form of the porous body as long as it has a countless number of holes, but it is preferable that the porous body is made of a metal material, and more specific examples include expanded metal, foamed sintered metal, metal mesh, punched metal, etc. Figure 6 shows a part of an expanded metal as an example. As can be seen from Figure 6, the expanded metal, which is a porous body of this type, is a porous body made of metal with countless diamond-shaped frames arranged vertically and horizontally, and the insides of the diamond-shaped frames are holes.

[0027] 2.6.2.Flow passage expansion member The flow path expansion member 22 is a member laminated on the surface of the porous body 21 opposite to the side that is overlaid on the cathode gas diffusion layer 14. The flow path expansion member 22 has a plurality of grooves 22a that open on the surface facing the porous body 21, and these grooves 22a function as a portion (gas flow path expansion portion) that expands the flow path of the oxidizing gas flowing through the porous body 21. This gas flow path expansion portion has wall portions 22b that extend in a direction inclined or perpendicular (not parallel) to the flow direction of the oxidizing gas indicated by the arrows in Figures 4 and 5. In this embodiment, the extension direction of the grooves 22a (gas flow path expansion portion) is perpendicular to the flow direction of the oxidizing gas. This can promote the diffusion of the oxidizing gas into the cathode gas diffusion layer 14 and reduce the pressure loss, as will be described in detail later.

[0028] Furthermore, the flow path expansion member 22 in this embodiment is provided with a groove 22c between adjacent grooves 22a, the groove 22c opening on the opposite side to the groove 22a. The groove 22a and the groove 22c are disposed on opposite sides of the flow path expansion member 22, and do not communicate with each other. The groove 22c opens to the anode separator 17 side of the adjacent power generating unit cell 10, and functions as a portion (enlarged cooling water channel portion) that enlarges the cooling water flow path (groove 17a) provided in the anode separator 17. The enlargement of the cooling water flow path will be described later.

[0029] The depth of grooves 22a, groove 22c, the pitch of adjacent grooves 22a (the center-to-center distance of grooves 22a), and the pitch of adjacent grooves 22c (the center-to-center distance of grooves 22c) can be adjusted appropriately taking into account pressure loss, but the depth can be 0.1 mm to 0.4 mm and the pitch can be 0.5 mm to 2.5 mm.

[0030] Furthermore, the shape of grooves 22a and 22c does not have to be a square as in this embodiment, but may be a rectangle, a trapezoid, a semicircle, a semi-ellipse as shown in FIG. 7, a triangle, or any other regular or irregular geometric shape.

[0031] The material constituting the flow path expansion member 22 may be any material that can be used as a separator for a power generation unit cell, and may be a gas-impermeable conductive material. Examples of such materials include dense carbon made by compressing carbon to make it gas-impermeable, and press-molded metal plates.

[0032] As can be seen from FIG. 2, the cathode separator 20 has an air inlet hole A at a position on one end side of the porous body 21 and the flow path expansion member 22 at a position on the outside of the power generation section 11 when the flow path expansion member 22 is extended from the power generation section 11. in , cooling water inlet hole W in , hydrogen outlet hole H out and an air outlet hole A is provided at the other end of the porous body 21 and the flow path expansion member 22. out , cooling water outlet hole W out , hydrogen inlet hole H in Here, the porous body 21 has an air inlet hole A at one end.in , the other end is air outlet hole A out It is connected to.

[0033] [Other examples of flow path expansion members] <Other form example 1> Fig. 8 is a diagram illustrating a flow path expansion member 22' according to another embodiment 1. Fig. 8 is a diagram illustrating the form of grooves 22'a forming the gas flow path expansion portion and grooves 22'c forming the cooling water path expansion portion when a part of the flow path expansion member 22' is viewed in plan (from the viewpoint of Fig. 1). The grooves 22'a and 22'c open on opposite sides of the flow path expansion member 22' and are alternately arranged, similar to the flow path expansion portion 22 described above. Grooves 22'a and 22'c in this embodiment extend along the oxidizing gas flow direction as a whole, unlike the flow path expansion member 22. However, grooves 22'a and 22'c extend in a wavy manner and have meandering wall surfaces, and therefore have wall portions 22'b that extend in a direction inclined or perpendicular (not parallel) to the oxidizing gas flow direction. These wall portions 22'b provide the same effect as wall portions 22b of the flow path expansion member 22.

[0034] In this embodiment, the distance between the crests of the waves of the grooves 22'a (the size of a in FIG. 8) can be appropriately adjusted in consideration of pressure loss, and can be set to 0.5 mm to 2.5 mm.

[0035] 9, the flow path expansion member 22' may be configured so that the direction in which the grooves 22'a and 22'c extend is perpendicular to the flow direction of the oxidizing gas. In this case, the grooves 22'a and 22'c extend in a wavy manner, but other than that, the grooves 22'a and 22'c have the same form as the flow path expansion member 22 described above.

[0036] The wavy shape of the wavy extension is not particularly limited, and may be a shape in which curves are combined and repeated as shown in Figures 8 and 9, as well as a triangular wave, a sine wave, a rectangular wave, or any other irregular wave shape.

[0037] <Other Example 2> 10 and 11 show a part of a flow path expansion member 122 according to another embodiment 2 together with the porous body 21. The porous body 21 is as described above. Fig. 10 is an external perspective view, and Fig. 11 is a cross-sectional view taken along CC in Fig. 10. In the above-mentioned flow path expansion member 22, the grooves 22a (gas flow path expansion portion) and the grooves 22c (cooling water flow path expansion portion) extend in the oxidizing gas flow direction and are arranged in a direction perpendicular to the oxidizing gas flow direction, but in this flow path expansion member 122 according to another embodiment 2, the grooves 122a (gas flow path expansion portion) and the grooves 122c (cooling water expansion portion) are repeatedly arranged in both directions (i.e., in-plane directions of the porous body 21). Even in this configuration, the wall portion 122b extends in a direction inclined or perpendicular (not parallel) to the direction in which the oxidizing gas flows. The wall portion 122b provides the same effect as the wall portion 22b of the flow path expansion member 22.

[0038] 2.7. Anode separator The anode separator 17 is a member that supplies a reactant gas (hydrogen) to the anode gas diffusion layer 16. FIG. The anode separator 17 is a member that is overlaid on the anode gas diffusion layer 16. The anode separator 17 has a plurality of grooves 17a that open on the surface facing the anode gas diffusion layer 16, and these grooves 17a serve as flow paths for supplying a reactant gas (hydrogen) to the anode gas diffusion layer 16. Therefore, the grooves 17a extend along the direction in which the reactant gas flows, as indicated by the straight arrow in FIG.

[0039] Furthermore, anode separator 17 in this embodiment has groove 17b between adjacent grooves 17a, which opens to the opposite side to groove 17a. Groove 17a and groove 17b are disposed on opposite sides of anode separator 17, and do not communicate with each other. The grooves 17b open into the grooves 22c in the cathode separator 20 of the adjacent power generating unit cell 10 to form flow paths for cooling water.

[0040] The depth of grooves 17a, grooves 17b, the pitch of adjacent grooves 17a (the distance between the centers of grooves 17a), and the pitch of adjacent grooves 17b (the distance between the centers of grooves 17b) can be adjusted as appropriate taking into account pressure loss, but the depth can be 0.1 mm to 0.4 mm and the pitch can be 0.5 mm to 2.5 mm.

[0041] Furthermore, the cross-sectional shape of the flow passage of the grooves 17a and 17b does not have to be a square as in this embodiment, but may be a rectangle, a trapezoid, a semicircle, a semi-ellipse, a triangle, or any other regular or irregular geometric shape.

[0042] The material constituting the anode separator 17 may be any material that can be used as a separator for a power generating unit cell, and may be a gas-impermeable conductive material. Examples of such materials include dense carbon made by compressing carbon to make it gas-impermeable, and a press-molded metal plate.

[0043] As can be seen from FIG. 2, the anode separator 17 is provided with an air inlet hole A at a position extending outward from the power generating section 11 and at one end of the groove 17a. in , cooling water inlet hole W in , hydrogen outlet hole H out An air outlet hole A is provided at the other end of the groove 17a and the groove 17b. out , cooling water outlet hole W out , hydrogen inlet hole H in Here, the groove 17a is a hydrogen inlet hole H in , hydrogen outlet hole H out The groove 17b is connected to the cooling water inlet hole W in , cooling water outlet hole W out It is connected to.

[0044] 2.8. Power Generation by the Power Generation Unit As is well known, power generation is performed by the power generation unit cell 10 described above as follows. When hydrogen is supplied from the grooves 17a of the anode separator 17, the hydrogen passes through the anode gas diffusion layer 16 and is converted into protons (H + ) and electrons (e- ), the protons pass through the electrolyte membrane 12 and the electrons pass through a conductive wire connected to the outside, and each reaches the cathode catalyst layer 13. Here, oxygen (air) is supplied to the cathode catalyst layer 13 from the cathode separator 20 via the cathode gas diffusion layer 14, and water (H2O) is generated in the cathode catalyst layer 13 by the protons, electrons, and oxygen. The generated water passes through the cathode gas diffusion layer 14 to the cathode separator 20 and is discharged. That is, in the power generating unit cell 10, the flow of electrons passing through the conductive wire connecting the anode catalyst layer 15 to the outside is utilized as an electric current.

[0045] 3. Effects etc. In the fuel cell 1 having the power generation unit cells 10 and the stack thereof, power is generated as described above. At this time, the cathode separator 20 and the anode separator 17 stacked in adjacent power generation unit cells 10 act as follows. Figs. 13 to 16 are explanatory views focusing on the portion where the stacked cathode separator 20 and the anode separator 17 are stacked. Fig. 13 is an external perspective view, Fig. 14 is a cross-sectional view taken along line DD in Fig. 13 (cross-sectional view showing the cooling water flow path), Fig. 15 is a cross-sectional view taken along line EE in Fig. 13 (cross-sectional view showing the reactive gas flow path), and Fig. 16 is a cross-sectional view taken from the same perspective as Fig. 14, for explaining the flow of oxidizing gas and cooling water. The oxidizing gas, cooling water, and reactive gas will be described below.

[0046] 3.1. Oxidizing gas A shown in Figure 2 in The oxidizing gas supplied from A out The fuel flows through the porous body 21 of the cathode separator 20 toward the cathode. As shown by the dotted arrows in Figure 16, the oxidizing gas flows through the porous body 21, but the flow path is expanded at the gas flow path expansion section (groove 22a, 22'a, 122a) along the way, and the presence of wall 22b (22'b, 122b) causes the oxidizing gas to be returned to the porous body 21 again. The flow path, which was once expanded, is then narrowed, and the flow speed of the oxidizing gas increases due to the Venturi effect, and the pressure at this section decreases according to Bernoulli's theorem. As a result, most of the gas flows into the porous body 21, where the pressure is low, and the diffusion effect of the oxidizing gas can be improved. Furthermore, the enlarged gas flow path portion (groove 22a, 22'a, 122a) expands the flow path, thereby reducing pressure loss in the flow path of the oxidizing gas. In particular, in the example shown in Fig. 8, the enlarged gas flow path portion (groove 22'a) is a wavy groove extending along the flow direction of the oxidizing gas, which is highly effective in reducing pressure loss. In addition, the flow velocity of the oxidizing gas increases particularly near the inflection point in the wavy shape, facilitating the flow of the oxidizing gas into the porous body 21.

[0047] 3.2. Cooling water The W shown in Fig. 2 in The cooling water supplied from W out The cooling water flows through the grooves 17b of the anode separator 17 toward the anode separator 17, but the flow path is expanded at the cooling water channel expansion section (groove 22c) along the way, as shown by the solid line in FIG. 16. This expands the flow path. The expansion of the cooling water flow path at this time is performed by the flow path expansion section and does not involve a change in the thickness of the anode separator 17, so there is no need to change the flow path cross section of the reactant gas flow path (groove 17a) of the anode separator 17. If the flow path cross-sectional area of ​​the reactant gas flow path is increased, the flow velocity of the reactant gas may become slower than expected. For example, if the flow rate of the reactant gas is small, the flow velocity of the reactant gas may not be sufficient, and the required diffusion of the reactant gas may not be achieved, or drainage may decrease due to a decrease in pressure loss in the flow path. That is, according to this embodiment, the cooling water passage expansion portion expands the cooling water passage of the anode separator 17, thereby improving the cooling capacity without changing the flow path of the reactant gas. In addition, the enlarged cooling water channel allows the cooling water to flow in the thickness direction of the power generating unit cell 10, which makes the cooling water moderately turbulent and allows for uniform cooling, thereby achieving a uniform in-plane power generation distribution and improving performance. When the enlarged cooling water channel (groove 22'c) is wavy and the reactant gas flow path (groove 17a) of the anode separator 17 is straight as in the example of Figure 8, the two flow paths intersect moderately, providing a high cooling effect.

[0048] 3.3.Reactive gas (hydrogen gas) The H shown in Fig. 2 in The reactant gas (hydrogen gas) supplied from out The reaction gas (hydrogen gas) flows toward the oxidizing gas and the cooling water in the grooves 17a of the anode separator 17 as shown by the dotted arrow in Fig. 15. In this embodiment, the flow direction of the reaction gas (hydrogen gas) and the flow direction of the oxidizing gas and the cooling water are in a counter-flow relationship. This allows efficient heat exchange. However, this is not limited to this, and they may be in a parallel flow relationship. [Explanation of symbols]

[0049] 1 fuel cell 10 Power generating unit cell 11 Power Generation Department 12 Electrolyte membrane 13 Cathode catalyst layer 14 Cathode gas diffusion layer 15 Anode catalyst layer 16 Anode gas diffusion layer 17 Anode separator 20 Cathode separator

Claims

1. A fuel cell comprising a power generation unit cell including a membrane assembly, an anode separator laminated on one side of the membrane assembly, and a cathode separator laminated on the other side of the membrane assembly, the power generation unit cells being laminated together in a plurality of units, the anode separator of one of the power generation unit cells and the cathode separator of another of the power generation unit cells adjacent to the one of the power generation unit cells are stacked together, the cathode separator has a porous body through which an oxidizing gas flows and a flow path expansion member, the flow path expansion member includes a plurality of gas flow path expansion sections that expand a flow path formed by the porous body on a side facing the porous body, and the gas flow path expansion sections have wall sections that are inclined or perpendicular to a flow direction of the oxidizing gas, the flow passage expansion member includes a cooling water passage expansion portion that expands a cooling water passage of the anode separator, the cooling water passage expansion portion being disposed between adjacent gas flow passage expansion portions on a side opposite to the porous body side; fuel cell.

2. The fuel cell according to claim 1 , wherein the enlarged gas flow passage portion is a groove.

3. The fuel cell according to claim 2 , wherein the grooves extend in a wavy pattern.

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