Separator for fuel cell

Abstract

To provide a separator for a fuel cell that can prevent a variation in the flow rate of reaction gas slipping into a gas diffusion layer depending on the position in a groove passage.SOLUTION: A separator 10 for a fuel cell has an opposite surface 10a opposite to a MEA. The opposite surface 10a has a plurality of groove passages 20A provided side by side in a width direction Y through which oxidation gas flows. The groove passage 20A has a bottom face that faces the MEA, and a first side face and a second side face that rise toward the MEA from one side and the other side of the bottom face in the width direction Y. The groove passage 20A is provided with a plurality of first areas 31 each having a first hydrophilic part 33 configured by performing hydrophilic treatment on the first side face, and a plurality of second areas 32 each having a second hydrophilic part 34 configured by performing hydrophilic treatment on the second side face. The first area 31 and the second area 32 are alternately provided in a longitudinal direction X that is an extension direction of the groove passage 20A.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a separator for a fuel cell.

Background Art

[0002] Patent Document 1 discloses a flow path. This flow path is provided in industrial products such as separators of fuel cells that require rapid discharge of fluids. The flow path is in the shape of a concave groove having a bottom surface and a pair of side surfaces that rise from both sides in the width direction of the bottom surface.

[0003] One of the side surfaces constituting the flow path and a half region of the bottom surface that is continuous with the same side surface in the width direction of the bottom surface are subjected to a hydrophilic treatment. The other side surface constituting the flow path and a half region of the bottom surface that is continuous with the other side surface in the width direction of the bottom surface are subjected to a water-repellent treatment.

[0004] In such a flow path, the fluid flows on one side that is subjected to the hydrophilic treatment in the width direction.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, when such a flow path is applied to, for example, a separator of a fuel cell, the following problems occur. That is, the generated water generated in the power generation part of the fuel cell is discharged from the gas diffusion layer of the power generation part to the flow path of the separator. At this time, the generated water is discharged to one side where hydrophilic treatment is performed in the width direction of the flow path. Therefore, the portion between the hydrophilic-treated portion of the inner surface of the flow path and the gas diffusion layer is blocked by the generated water, so that the flow of the reaction gas flowing through the flow path is biased to the other side in the width direction of the flow path. As a result, there are portions where the reaction gas easily penetrates into the gas diffusion layer and portions where it is difficult to penetrate. As a result, there is a risk of a decrease in the power generation amount of the fuel cell.

[0007] An object of the present invention is to provide a separator for a fuel cell that can suppress variations in the flow rate of the reaction gas penetrating into the gas diffusion layer depending on the position in the groove flow path.

Means for Solving the Problems

[0008] A separator for a fuel cell for achieving the above object is a separator for a fuel cell having a facing surface facing the power generation part of the fuel cell, wherein a plurality of groove flow paths through which the reaction gas flows are provided side by side in the width direction of the groove flow path on the facing surface, and the groove flow path has a bottom surface facing the power generation part, and a first side surface and a second side surface that stand up from one side and the other side of the bottom surface in the width direction toward the power generation part, respectively. The groove flow path has a plurality of first regions having a first hydrophilic part formed by hydrophilic treatment of the first side surface, and a plurality of second regions having a second hydrophilic part formed by hydrophilic treatment of the second side surface, which are alternately provided in the extending direction of the groove flow path.

[0009] According to the same configuration, the generated water generated in the power generation unit is easily discharged from the gas diffusion layer to the first hydrophilic part of the first region and the second hydrophilic part of the second region. Therefore, even when the space between each hydrophilic part and the gas diffusion layer is blocked by the generated water, the reaction gas flows in a meandering manner through the groove flow path, so that the flow of the reaction gas is suppressed from being biased to one side in the width direction of the groove flow path. Accordingly, it is possible to suppress the variation in the flow rate of the reaction gas that penetrates into the gas diffusion layer depending on the position in the groove flow path.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, with reference to FIGS. 1 to 4, an embodiment of a separator for a fuel cell will be described. In the present embodiment, the present invention is embodied as a separator on the cathode side having a flow path through which an oxidizing gas flows. In each drawing, for convenience of explanation, a part of the configuration is shown in an exaggerated or simplified manner, so the dimensional ratios of each configuration may be different from the actual ones.

[0012] <Basic Configuration of Separator 10 for Fuel Cell> As shown in FIGS. 1 to 3, the separator 10 for a fuel cell is formed in a rectangular plate shape in a plan view by press-molding a metal member such as titanium or stainless steel.

[0013] Hereinafter, the direction in which the long side of the separator 10 extends will be described as the longitudinal direction X, and the direction in which the short side of the separator 10 extends will be described as the width direction Y. As shown in Fig. 1, at the end of one side in the longitudinal direction X of the separator 10 (the right side in the left - right direction of Fig. 1), a fuel gas supply manifold 11, a cooling medium supply manifold 13, and an oxidizing gas discharge manifold 16 are provided. Each of the manifolds 11, 13, 16 is provided in order from the other side in the width direction Y (the upper side in the up - down direction of Fig. 1) toward one side (the lower side of Fig. 1).

[0014] Also, at the end of the other side in the longitudinal direction X of the separator 10 (the left side in Fig. 1), a fuel gas discharge manifold 12, a cooling medium discharge manifold 14, and an oxidizing gas supply manifold 15 are provided. Each of the manifolds 12, 14, 15 is provided in order from one side in the width direction Y (the lower side in Fig. 1) toward the other side (the upper side in Fig. 1).

[0015] The fuel gas is, for example, hydrogen gas. Also, the cooling medium is, for example, cooling water. Also, the oxidizing gas is, for example, air. As shown in Fig. 1, on the first surface 10A of the separator 10, a plurality of groove flow paths 20A and connection flow paths 20B that connect the groove flow paths 20A and the manifolds 15, 16 are provided. Both the groove flow paths 20A and the connection flow paths 20B are flow paths through which the oxidizing gas as a reaction gas flows.

[0016] As shown in Figs. 1 - 3, the groove flow paths 20A are composed of an uneven shape formed on the opposing surface 10a of the first surface 10A that faces the membrane - electrode assembly (hereinafter, MEA40). In this embodiment, MEA40 corresponds to the power generation unit according to the present invention. Hereinafter, the opposing direction between MEA40 and the separator 10 will be simply described as the opposing direction Z.

[0017] The groove flow paths 20A extend linearly in the longitudinal direction X. The groove flow paths 20A are arranged at equal intervals from each other in the width direction Y. In this embodiment, the longitudinal direction X corresponds to the extending direction of the groove flow path according to the present invention, and the width direction Y corresponds to the width direction of the groove flow path according to the present invention.

[0018] The connection channel 20B is composed of a concavo-convex shape formed on the surface 10b of the first surface 10A that is located on the outer peripheral side of the opposing surface 10a. The connection channel 20B extends from both ends of the groove channel 20A in the longitudinal direction X toward the manifolds 15 and 16, respectively.

[0019] The oxidation gas supply manifold 15 and the oxidation gas discharge manifold 16 are communicated with each other by the groove channel 20A and the connection channel 20B. <Groove channel 20A> Hereinafter, the configuration of the groove channel 20A will be described in more detail. In the following, the upstream side and the downstream side in the flow direction of the oxidation gas in the groove channel 20A will be simply described as the upstream side and the downstream side.

[0020] As shown in FIGS. 2 and 3, the groove channel 20A has a bottom surface 23, a first side surface 21, and a second side surface 22. The bottom surface 23 faces the gas diffusion layer (hereinafter, GDL41) of the MEA40.

[0021] The first side surface 21 stands up from one side of the bottom surface 23 in the width direction Y (the right side in the left-right direction of FIG. 2) toward the GDL41. The second side surface 22 stands up from the other side of the bottom surface 23 in the width direction Y (the left side in FIG. 2) toward the GDL41.

[0022] <First region 31, second region 32> As shown in FIG. 1, the groove channel 20A has a plurality of first regions 31 and a plurality of second regions 32.

[0023] The first regions 31 and the second regions 32 are alternately provided over the entire groove channel 20A in the longitudinal direction X. A gap S is provided between the first regions 31 and the second regions 32 in the longitudinal direction X.

[0024] In each of the five groove channels 20A, the first regions 31 and the second regions 32 are alternately provided in the longitudinal direction X. As shown in FIG. 2, the first region 31 has a hydrophilic first hydrophilic portion 33 and a water-repellent first water-repellent portion 35.

[0025] The first hydrophilic portion 33 is formed by subjecting a first side surface 21 and a part of a bottom surface 23 (hereinafter referred to as a first bottom surface 23A) continuous with the first side surface 21 to a hydrophilic treatment. As the hydrophilic treatment, for example, a method such as performing a surface treatment such as plasma treatment on the surface of the base material of the separator 10 to generate hydrophilic functional groups on the surface of the base material can be used.

[0026] Generated water W drawn from the GDL 41 through the first side surface 21 stays in contact with both the first side surface 21 and the first bottom surface 23A in the first hydrophilic portion 33. The first water-repellent portion 35 is formed by subjecting a second side surface 22 and a part of a bottom surface 23 (hereinafter referred to as a second bottom surface 23B) continuous with the second side surface 22 to a water-repellent treatment. The second bottom surface 23B is a portion of the bottom surface 23 in the first region 31 other than the first bottom surface 23A. As the water-repellent treatment, for example, a method such as coating the surface of the base material with a fluororesin such as polytetrafluoroethylene (PTFE) to form a water-repellent film on the surface of the base material can be used.

[0027] In addition, the "hydrophilic (property)" in the present embodiment refers to a property of having a small contact angle with a fluid (in this embodiment, the generated water W), and the contact angle includes a range of 0 degrees or more and 90 degrees or less. Further, the "water-repellent (property)" in the present embodiment refers to a property of having a large contact angle with a fluid (generated water W), and the contact angle includes a range of more than 90 degrees and 180 degrees or less.

[0028] As shown in FIG. 1, the length of the first region 31 in the longitudinal direction X is constant over the entire width direction Y. The length of the first region 31 in the longitudinal direction X is preferably 10 mm or more. As shown in Fig. 2, the surface area of the first hydrophilic portion 33 is preferably 40% or less of the surface area of the entire first region 31. Specifically, the length L1 of the first bottom surface 23A of the first hydrophilic portion 33 in the width direction Y is preferably 40% or less of the length L3 of the bottom surface 23 in the width direction Y, and the length L2 of the second bottom surface 23B of the first water-repellent portion 35 in the width direction Y is preferably 60% or more of the length L3 of the bottom surface 23.

[0029] As shown in Fig. 1, the length L1 increases toward the downstream side of the groove flow path 20A. That is, the length L1A in the first region 31A on the upstream side is smaller than the length L1B in the first region 31B located at the center of the groove flow path 20A in the longitudinal direction X (L1A < L1B). Also, the length L1B is smaller than the length L1C in the first region 31C on the downstream side (L1B < L1C). Note that in Fig. 1, the first region 31 is shown in a simplified manner.

[0030] As shown in Fig. 3, the second region 32 is provided with a hydrophilic second hydrophilic portion 34 and a water-repellent second water-repellent portion 36. The second hydrophilic portion 34 is formed by subjecting the second side surface 22 and a part of the bottom surface 23 (hereinafter referred to as the third bottom surface 23C) continuous with the second side surface 22 to a hydrophilic treatment. As the hydrophilic treatment, similar to the first hydrophilic portion 33, surface treatment such as plasma treatment can be used.

[0031] Generated water W drawn from the GDL 41 through the second side surface 22 stays in contact with both the second side surface 22 and the third bottom surface 23C in the second hydrophilic portion 34. The second water-repellent portion 36 is formed by subjecting the first side surface 21 and a part of the bottom surface 23 (hereinafter referred to as the fourth bottom surface 23D) continuous with the first side surface 21 to a water-repellent treatment. The fourth bottom surface 23D is the portion of the bottom surface 23 in the second region 32 other than the third bottom surface 23C. As the water-repellent treatment, similar to the first water-repellent portion 35, a method such as coating the surface of the base material with a fluororesin can be used.

[0032] As shown in FIG. 1, the length of the second region 32 in the longitudinal direction X is constant throughout the width direction Y. The length of the second region 32 in the longitudinal direction X is preferably 10 mm or more. As shown in FIG. 3, the surface area of the second hydrophilic portion 34 is preferably 40% or less of the surface area of the entire second region 32. Specifically, the length L4 of the third bottom surface 23C of the second hydrophilic portion 34 in the width direction Y is 40% or less of the length L3 of the bottom surface 23 in the width direction Y, and the length L5 of the fourth bottom surface 23D of the second water-repellent portion 36 in the width direction Y is preferably 60% or more of the length L3 of the bottom surface 23.

[0033] As shown in FIG. 1, the length L4 is increased toward the downstream side of the groove flow path 20A. That is, the length L4A in the second region 32A on the upstream side is smaller than the length L4B in the second region 32B located at the center of the groove flow path 20A in the longitudinal direction X (L4A < L4B). Further, the length L4B is smaller than the length L4C in the second region 32C on the downstream side (L4B < L4C). In FIG. 1, like the first region 31, the second region 32 is also shown in a simplified manner.

[0034] Next, the operation of the present embodiment will be described. As shown in FIGS. 2 to 4, the generated water W generated by the MEA 40 is easily discharged from the GDL 41 to the first hydrophilic portion 33 of the first region 31 and the second hydrophilic portion 34 of the second region 32. Therefore, the space between each hydrophilic portion 33, 34 and the GDL 41 is blocked by the generated water W (see FIGS. 2 and 3). Even in such a case, according to the configuration of the present embodiment, since the oxidizing gas meanders and flows through the groove flow path 20A, the flow of the oxidizing gas in the width direction Y is suppressed from being biased to one side of the groove flow path 20A (see FIG. 4).

[0035] Next, the effects of the present embodiment will be described. (1) The groove flow path 20A has a bottom surface 23 facing the GDL 41 of the MEA 40, and a first side surface 21 and a second side surface 22 that stand up from one side and the other side of the bottom surface 23 in the width direction Y toward the GDL 41, respectively. The groove flow path 20A is provided with a plurality of first regions 31 having a first hydrophilic portion 33 formed by hydrophilically treating the first side surface 21, and a plurality of second regions 32 having a second hydrophilic portion 34 formed by hydrophilically treating the second side surface 22. The first regions 31 and the second regions 32 are alternately provided in the longitudinal direction X, which is the extending direction of the groove flow path 20A.

[0036] According to such a configuration, the above-described operation is achieved. Therefore, it is possible to suppress variations in the flow rate of the oxidizing gas that penetrates into the GDL 41 depending on the position within the groove flow path 20A. (2) A gap S is provided between the first region 31 and the second region 32 in the longitudinal direction X.

[0037] When there is no gap S between the first region 31 and the second region 32 in the longitudinal direction X, the generated water W discharged to the first hydrophilic portion 33 and the generated water W discharged to the second hydrophilic portion 34 are connected, and thus the groove flow path 20A is likely to be blocked. Therefore, there is a possibility that the pressure loss of the oxidizing gas increases.

[0038] In this regard, according to the above configuration, a gap S is provided between the first region 31 and the second region 32 in the longitudinal direction X. Therefore, the blockage of the groove flow path 20A described above is suppressed. Therefore, it is possible to suppress an increase in the pressure loss of the oxidizing gas flowing through the groove flow path 20A.

[0039] (3) The first region 31 has a first water-repellent portion 35 formed by water-repellently treating the second side surface 22. The second region 32 has a second water-repellent portion 36 formed by water-repellently treating the first side surface 21.

[0040] According to such a configuration, the first region 31 is composed of a first hydrophilic portion 33 and a first water-repellent portion 35, and the second region 32 is composed of a second hydrophilic portion 34 and a second water-repellent portion 36. Therefore, the generated water W generated in the MEA 40 is more likely to be discharged from the GDL 41 to the first hydrophilic portion 33 of the first region 31 and the second hydrophilic portion 34 of the second region 32. Accordingly, the effect of the invention according to (1) can be preferably exhibited.

[0041] (4) The first region 31 and the second region 32 are provided on the downstream side from the central portion of the groove flow path 20A in the longitudinal direction X. The amount of the generated water W generated in the MEA 40 is the largest at the central portion of the MEA 40 in the longitudinal direction X. Therefore, in the groove flow path 20A, it is desirable that the generated water W be efficiently discharged in the portion from the central portion to the downstream side. In this regard, according to the above configuration, the first region 31 and the second region 32 are provided on the downstream side from the central portion of the groove flow path 20A in the longitudinal direction X. Accordingly, the generated water W can be efficiently discharged from the GDL 41.

[0042] (5) The first hydrophilic portion 33 has a first side surface 21 and a first bottom surface 23A continuous with the first side surface 21. The second hydrophilic portion 34 has a second side surface 22 and a third bottom surface 23C continuous with the second side surface 22.

[0043] According to such a configuration, the generated water W drawn out from the GDL 41 via the first side surface 21 is in a state of contacting both the first side surface 21 and the first bottom surface 23A in the first hydrophilic portion 33. Thereby, the discharged generated water W is likely to stay in the first hydrophilic portion 33. Similarly, in the second region 32 as well, the discharged generated water W is likely to stay in the second hydrophilic portion 34. Accordingly, the effect of the invention according to (1) can be more preferably exhibited.

[0044] (6) The first region 31 and the second region 32 are alternately provided over the entire groove flow path 20A in the longitudinal direction X. According to such a configuration, the operational effects of the invention according to (1) can be exerted over the entire extending direction of the groove flow path 20A. Therefore, it is possible to suppress variations in the flow rate of the oxidizing gas that penetrates into the GDL 41 depending on the position over the entire groove flow path 20A in the longitudinal direction X.

[0045] (7) The length L1 of the first bottom surface 23A of the first hydrophilic portion 33 in the width direction Y and the length L4 of the third bottom surface 23C of the second hydrophilic portion 34 in the width direction Y are larger toward the downstream side of the groove flow path 20A.

[0046] When the first hydrophilic portion 33 and the second hydrophilic portion 34 are provided on the upstream side of the groove flow path 20A, generated water W may be excessively drawn out from the GDL 41 on the upstream side. In this case, when the humidity of the MEA 40 decreases, the power generation amount of the fuel cell may conversely decrease.

[0047] In this regard, according to the above configuration, the length L1 of the first bottom surface 23A of the first hydrophilic portion 33 and the length L4 of the third bottom surface 23C of the second hydrophilic portion 34 in the width direction Y are larger toward the downstream side of the groove flow path 20A. That is, the surface area of each of the hydrophilic portions 33, 34 is smaller toward the upstream side. Therefore, it becomes difficult for the generated water W to be drawn out from the GDL 41 to the first hydrophilic portion 33 and the second hydrophilic portion 34 on the upstream side of the groove flow path 20A compared to the downstream side. Therefore, it is possible to suppress a decrease in the humidity of the MEA 40 on the upstream side.

[0048] (8) In each of the plurality of groove flow paths 20A, a first region 31 and a second region 32 are alternately provided in the longitudinal direction X. According to such a configuration, in each of the plurality of groove flow paths 20A, the operational effects of the invention according to (1) are exerted. Therefore, it is possible to suppress variations in the flow rate of the oxidizing gas that penetrates into the GDL 41 depending on the position within the groove flow path 20A over the entire MEA 40.

[0049] <Modification Example> This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0050] · The number of the groove flow paths 20A is not limited to the five exemplified in the present embodiment, and may be four or less, or six or more. · The separator 10 does not have to be configured such that the first region 31 and the second region 32 are alternately provided in the longitudinal direction X in each of the plurality of groove flow paths 20A as exemplified in the present embodiment. The separator 10 only needs to have the first region 31 and the second region 32 alternately provided in the longitudinal direction X in at least one of the plurality of groove flow paths 20A. In this case, in the groove flow paths other than those in which the first region 31 and the second region 32 are alternately provided in the longitudinal direction X among the plurality of groove flow paths 20A, the first region 31 and the second region 32 may be provided in any number and arrangement, or the first region 31 and the second region 32 may be omitted.

[0051] · The length L4 of the third bottom surface 23C of the second hydrophilic portion 34 is not limited to being larger toward the downstream side of the groove flow path 20A as exemplified in the present embodiment. For example, the length L4 may be constant in the longitudinal direction X which is the extending direction of the groove flow path 20A. In this case, the length L4A, the length L4B, and the length L4C are the same (L4A = L4B = L4C).

[0052] · The length L1 of the first bottom surface 23A of the first hydrophilic portion 33 is not limited to being larger toward the downstream side of the groove flow path 20A as exemplified in the present embodiment. For example, the length L1 may be constant in the longitudinal direction X which is the extending direction of the groove flow path 20A. In this case, the length L1A, the length L1B, and the length L1C are the same (L1A = L1B = L1C).

[0053] · The first region 31 and the second region 32 are not limited to being provided over the entire length of the groove flow path 20A in the longitudinal direction X. The first region 31 and the second region 32 only need to be provided at least from the central portion to the downstream side of the groove flow path 20A in the longitudinal direction X.

[0054] · As exemplified in this embodiment, the first region 31 and the second region 32 do not necessarily have to be provided on the downstream side from the central portion of the groove channel 20A in the longitudinal direction X. As long as the first region 31 and the second region 32 are alternately provided in the longitudinal direction X, the first region 31 and the second region 32 may be arranged at any position in the extending direction of the groove channel 20A.

[0055] · The second hydrophilic portion 34 is not limited to including the third bottom surface 23C. That is, the second hydrophilic portion 34 may be configured by subjecting only the second side surface 22 to hydrophilic treatment. · The first hydrophilic portion 33 is not limited to including the first bottom surface 23A. That is, the first hydrophilic portion 33 may be configured by subjecting only the first side surface 21 to hydrophilic treatment.

[0056] · The water repellent treatment is not limited to the method using the fluororesin exemplified in this embodiment, and any surface treatment method can be used as long as it forms a water repellent film on the surface of the base material of the separator 10.

[0057] · The hydrophilic treatment is not limited to the plasma treatment exemplified in this embodiment, and any surface treatment method that forms a hydrophilic film on the surface of the base material of the separator 10 can also be used. · The second region 32 does not necessarily have to be subjected to water repellent treatment for the second water repellent portion 36. In this case, since the metal separator 10 has water repellency, as long as the second hydrophilic portion 34 is formed, the portion other than the second hydrophilic portion 34 in the second region 32 naturally becomes the second water repellent portion.

[0058] · The first region 31 does not necessarily have to be subjected to water repellent treatment for the first water repellent portion 35. In this case, since the metal separator 10 has water repellency, as long as the first hydrophilic portion 33 is formed, the portion other than the first hydrophilic portion 33 in the first region 31 naturally becomes the first water repellent portion.

[0059] ·The groove flow path 20A is not limited to having a gap S provided between the first region 31 and the second region 32 in the longitudinal direction X. That is, the first region 31 and the second region 32 may be adjacent in the longitudinal direction X.

[0060] ·The separator for a fuel cell according to the present invention is not limited to the cathode-side separator 10 exemplified in the present embodiment, and can also be applied to the anode-side separator.

Explanation of reference numerals

[0061] L1, L1A, L1B, L1C... Length L2... Length L3... Length L4, L4A, L4B, L4C... Length L5... Length S... Gap W... Generated water X... Longitudinal direction Y... Width direction Z... Opposite direction 10... Separator 10A... First surface 10a... Opposite surface 10b... Surface 11... Fuel gas supply manifold 12... Fuel gas discharge manifold 13... Cooling medium supply manifold 14... Cooling medium discharge manifold 15... Oxidizing gas supply manifold 16... Oxidizing gas discharge manifold 20A... Groove flow path 20B... Connection flow path 21... First side surface 22... Second side surface 23... Bottom surface 23A... First bottom surface 23B... Second bottom surface 23C... Third bottom surface 23D... Fourth bottom surface 31, 31A, 31B, 31C... First region 32, 32A, 32B, 32C... Second region 33... First hydrophilic part 34…Second hydrophilic part 35…First water-repellent part 36…Second water-repellent part 40…MEA 41…GDL

Claims

1. A separator for a fuel cell having a facing surface facing the power generation section of the fuel cell, wherein a plurality of groove flow paths through which a reaction gas flows are provided side by side in the width direction of the groove flow paths on the facing surface, the groove flow path has a bottom surface facing the power generation section, and a first side surface and a second side surface that stand up from one side and the other side of the bottom surface in the width direction toward the power generation section, respectively, the groove flow path includes a plurality of first regions having a first hydrophilic portion formed by subjecting the first side surface to a hydrophilic treatment, and a plurality of second regions having a second hydrophilic portion formed by subjecting the second side surface to a hydrophilic treatment, which are alternately provided in the extending direction of the groove flow path, A separator for a fuel cell.

2. A gap is provided between the first region and the second region in the extending direction, The separator for a fuel cell according to Claim 1.

3. The first region has a first water-repellent portion formed by subjecting the second side surface to a water-repellent treatment, The second region has a second water-repellent portion formed by subjecting the first side surface to a water-repellent treatment, The separator for a fuel cell according to Claim 1 or Claim 2.

4. When the downstream side in the flow direction of the reaction gas in the groove flow path is defined as the downstream side, the first region and the second region are provided downstream from the central portion of the groove flow path in the extending direction, The separator for a fuel cell according to any one of Claims 1 to 3.

5. The first hydrophilic portion includes the first side surface and a part of the bottom surface continuous with the first side surface, The second hydrophilic portion includes the second side surface and a part of the bottom surface continuous with the second side surface, The separator for a fuel cell according to any one of Claims 1 to 4.

6. The first region and the second region are alternately provided over the entire groove flow path in the extending direction, The separator for a fuel cell according to Claim 5.

7. The length of the bottom surface of the first hydrophilic portion in the width direction and the length of the bottom surface of the second hydrophilic portion in the width direction are larger toward the downstream side of the groove flow path, The separator for a fuel cell according to Claim 6.

8. In each of the plurality of groove flow paths, the first region and the second region are alternately provided in the extending direction, The separator for a fuel cell according to any one of Claims 1 to 7.

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