Single cell of a fuel cell

Abstract

To provide a single cell for a fuel cell, capable of preventing a gas diffusion layer from sinking into groove passages, while suppressing a decrease in diffusivity of a reactant gas.SOLUTION: A single cell 90 for a fuel cell includes a power generating unit 10 and a pair of separators 30, 40. The separator 30 includes a facing surface 30a which faces the power generating unit 10. The facing surface 30a includes: a plurality of groove passages 37A where a fuel gas flows; and a plurality of ribs 37C each of which is located between the groove passages 37A and projects toward the power generating unit 10. Each of the plurality of ribs 37C includes a top wall portion 51 in contact with the power generating unit 10, a pair of side wall portions 52 located on both sides of the top wall portion 51 in a third direction Z, and corner portions 53 each of which is located between the top wall portion 51 and one of the side wall portions 52. A restricting portion 70 is provided at a portion of each corner portion 53 that faces the groove passage 37A, the restricting portion restricting sinking of a gas diffusion layer 16 into the groove passage 37A. The restricting portion 70 is a conductive porous body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a single cell of a fuel cell.

Background Art

[0002] Patent Document 1 discloses a fuel cell. This fuel cell includes a power generation unit called an electrolyte membrane - electrode structure, and a resin frame member disposed on the outer peripheral side of the power generation unit. The fuel cell also includes a pair of separators that sandwich the power generation unit and the frame member.

[0003] The power generation unit has a solid polymer electrolyte membrane, and an anode electrode and a cathode electrode that sandwich the solid polymer electrolyte membrane. The anode electrode and the cathode electrode have a catalyst layer and a gas diffusion layer laminated on the catalyst layer.

[0004] On the surface of the separator facing the power generation unit, a groove flow path through which a fuel gas or an oxidant gas (hereinafter, a reaction gas) flows is formed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in such a fuel cell, a part of the gas diffusion layer facing the groove flow path may bend and deform, and thus may sink into the groove flow path. In this case, since the sunken gas diffusion layer becomes the ventilation resistance of the reaction gas flowing through the groove flow path, there is a risk of increasing the pressure loss of the reaction gas.

[0007] An object of the present invention is to provide a single cell of a fuel cell that can suppress the sinking of a gas diffusion layer into a groove flow path while suppressing a decrease in the diffusibility of a reaction gas. **Means for Solving the Problems**

[0008] A single cell of a fuel cell for achieving the above object includes a power generation unit having a membrane electrode assembly and a pair of gas diffusion layers sandwiching the membrane electrode assembly, and a pair of separators sandwiching the power generation unit. The pair of separators has a facing surface facing the power generation unit. The facing surface has a plurality of groove flow paths through which a reaction gas flows and a plurality of ribs that are located between the groove flow paths and protrude toward the power generation unit. The plurality of ribs have a top wall portion that contacts the power generation unit, a pair of side wall portions that are located on both sides of the top wall portion in the arrangement direction of the plurality of groove flow paths, and a corner portion that is located between the top wall portion and the side wall portion. A regulating portion for regulating the sinking of the gas diffusion layer into the groove flow path is provided at a portion of the corner portion facing the groove flow path. The regulating portion is a porous body having conductivity.

[0009] According to the same configuration, the sinking of the gas diffusion layer into the groove flow path is regulated by the regulating portion. Further, since the regulating portion is a porous body having conductivity, a part of the reaction gas flowing through the groove flow path passes through the inside of the regulating portion and diffuses into the inside of the gas diffusion layer. Therefore, it is possible to suppress the sinking of the gas diffusion layer into the groove flow path while suppressing a decrease in the diffusibility of the reaction gas. **Brief Description of the Drawings**

[0010]

Figure 1

Figure 2

Figure 3

[0011] Hereinafter, with reference to FIGS. 1 and 2, an embodiment of a single cell of a fuel cell will be described. Note that 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. In addition, "orthogonal" in the following description includes not only the case of strict orthogonality but also the case of substantially perpendicular intersection within the range where the effects of each embodiment are exhibited.

[0012] <Single cell 90 of the fuel cell> As shown in FIGS. 1 and 2, the single cell 90 of the fuel cell includes a power generation unit 10, a frame member 20 that holds the power generation unit 10, a pair of separators 30 and 40 that sandwich the power generation unit 10 and the frame member 20, and restricting units 70 and 80. Note that in FIG. 1, the illustration of the restricting units 70 and 80 is omitted. In addition, FIG. 2 shows a state in which a plurality of single cells 90 are stacked along the vertical direction with the separator 30 facing vertically downward.

[0013] The single cell 90 is rectangular plate-shaped as a whole. Hereinafter, the stacking direction of the separator 30, the power generation unit 10, the frame member 20, and the separator 40 will be described as the first direction X. In the present embodiment, the first direction X is the vertical direction. In addition, among the directions orthogonal to the first direction X, the longitudinal direction of the single cell 90 will be described as the second direction Y. Further, the direction orthogonal to both the first direction X and the second direction Y will be described as the third direction Z.

[0014] The single cell 90 has inlet-side manifolds 91, 93, 95 for introducing reaction gas and a cooling medium into the single cell 90, and outlet-side manifolds 92, 94, 96 for discharging the reaction gas and the cooling medium in the single cell 90 to the outside. In this embodiment, the inlet-side manifold 91 and the outlet-side manifold 92 are manifolds through which the fuel gas among the reaction gases flows. The fuel gas is, for example, hydrogen gas. Also, the inlet-side manifold 93 and the outlet-side manifold 94 are manifolds through which the cooling medium flows. The cooling medium is, for example, cooling water. Further, the inlet-side manifold 95 and the outlet-side manifold 96 are manifolds through which the oxidant gas among the reaction gases flows. The oxidant gas is, for example, air.

[0015] The inlet-side manifolds 91, 93, 95 and the outlet-side manifolds 92, 94, 96 are rectangular in plan view and penetrate the single cell 90 in the first direction X. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are provided at the end on one side (the left side in the left-right direction of FIG. 1) of the single cell 90 in the second direction Y. The inlet-side manifold 91 and the outlet-side manifolds 94, 96 are arranged in order from one side (the back side of the paper surface of FIG. 1) in the third direction Z to the other side (the front side of the paper surface of FIG. 1).

[0016] The outlet-side manifold 92 and the inlet-side manifolds 93, 95 are provided at the end on the other side (the right side of FIG. 1) of the single cell 90 in the second direction Y. The outlet-side manifold 92 and the inlet-side manifolds 93, 95 are arranged in order from the other side (the front side of the paper surface of FIG. 1) in the third direction Z to one side (the back side of the paper surface of FIG. 1).

[0017] Hereinafter, each component of the single cell 90 will be described in detail. <Power generation unit 10> As shown in FIGS. 1 and 2, the power generation unit 10 has a solid polymer electrolyte membrane (hereinafter referred to as the electrolyte membrane 11) and electrodes 12 and 13 provided on both sides of the electrolyte membrane 11. In the present embodiment, the electrode joined to one side (the lower side in the vertical direction in FIG. 1) of the electrolyte membrane 11 in the first direction X is the anode electrode 12. Also, the electrode joined to the other side (the upper side in FIG. 1) of the electrolyte membrane 11 in the first direction X is the cathode electrode 13.

[0018] The anode electrode 12 has a catalyst layer 14 joined to one side (the lower side in FIG. 1) of the electrolyte membrane 11 and a gas diffusion layer 16 joined to the catalyst layer 14. The cathode electrode 13 has a catalyst layer 15 joined to the other side (the upper side in FIG. 1) of the electrolyte membrane 11 and a gas diffusion layer 17 joined to the catalyst layer 15.

[0019] That is, a membrane catalyst layer assembly composed of the electrolyte membrane 11 and a pair of catalyst layers 14 and 15 is sandwiched between a pair of gas diffusion layers 16 and 17. In the present embodiment, the above membrane catalyst layer assembly corresponds to the membrane electrode assembly according to the present invention.

[0020] <Frame member 20> As shown in FIG. 1, the frame member 20 has a rectangular frame shape that is long in the second direction Y and is formed of, for example, a synthetic resin material.

[0021] The frame member 20 has through holes 21, 22, 23, 24, 25, and 26 that constitute the manifolds 91, 92, 93, 94, 95, and 96, respectively. The frame member 20 has an opening 27 at the center. The power generation unit 10 is joined to the periphery of the opening 27 from the other side (the upper side in FIG. 1) in the first direction X.

[0022] <Separator 30> As shown in FIGS. 1 and 2, the separator 30 is formed by press-molding a rectangular metal plate made of, for example, titanium or stainless steel in a plan view.

[0023] The separator 30 has through holes 31, 32, 33, 34, 35, 36 that constitute each of the manifolds 91, 92, 93, 94, 95, 96 (see FIG. 1). The separator 30 has a first surface 30A having a facing surface 30a that faces the anode electrode 12 of the power generation unit 10 in the first direction X, and a second surface 30B having a surface 30b on the side opposite to the facing surface 30a.

[0024] On the first surface 30A, a plurality of groove flow paths 37A through which fuel gas flows, a pair of connection parts 37B, and a plurality of ribs 37C that are located between the groove flow paths 37A and protrude toward the gas diffusion layer 16 of the power generation unit 10 are provided. In FIG. 1, the groove flow paths 37A, the connection parts 37B, and the ribs 37C are shown in a simplified manner.

[0025] The plurality of groove flow paths 37A and the plurality of ribs 37C are provided on the facing surface 30a. The groove flow paths 37A are arranged side by side with a space therebetween in the third direction Z (see FIG. 2). Each of the plurality of groove flow paths 37A extends linearly in the second direction Y (see FIG. 1). In the present embodiment, the second direction Y corresponds to the extending direction of the groove flow path according to the present invention, and the third direction Z corresponds to the arrangement direction of the plurality of groove flow paths according to the present invention.

[0026] The ribs 37C are arranged side by side with a space therebetween in the third direction Z (see FIG. 2). Each of the plurality of ribs 37C extends linearly in the second direction Y (see FIG. 1). As shown in FIG. 2, each of the plurality of ribs 37C has a top wall portion 51, a pair of side wall portions 52 located on both sides of the top wall portion 51 in the third direction Z, and a corner portion 53 located between the top wall portion 51 and the side wall portions 52.

[0027] The top wall portion 51 is in contact with the gas diffusion layer 16 of the power generation unit 10. In the present embodiment, the top wall portion 51 is in contact with the gas diffusion layer 16 over the entire rib 37C in the second direction Y.

[0028] The pair of side wall portions 52 are inclined such that the distance between them in the third direction Z increases as they move away from the gas diffusion layer 16 in the first direction X. The corner portion 53 is curved so as to move away from the gas diffusion layer 16 in the first direction X as it moves away from the top wall portion 51 in the third direction Z.

[0029] As shown in FIG. 1, the pair of connection portions 37B extend from both sides of the plurality of groove flow paths 37A toward the through holes 31 and 32 in the second direction Y. The fuel gas is introduced from the inlet side manifold 91 into the plurality of groove flow paths 37A through one of the connection portions 37B. Further, the fuel gas flowing through the plurality of groove flow paths 37A is discharged to the outlet side manifold 92 through the other connection portion 37B.

[0030] As shown in FIGS. 1 and 2, on the second surface 30B, a plurality of groove flow paths 38A through which a cooling medium flows, a pair of connection portions 38B, and a plurality of ribs 38C that are located between the groove flow paths 38A and project toward the side opposite to the rib 37C in the first direction X are provided. In FIG. 1, the groove flow paths 38A, the connection portions 38B, and the ribs 38C are shown in a simplified manner.

[0031] As shown in FIG. 2, the groove flow path 38A is formed by the back side of the rib 37C. Further, the rib 38C is formed by the back side of the groove flow path 37A. The pair of connection portions 38B shown by the dashed line in FIG. 1 extend from both sides of the plurality of groove flow paths 38A toward the through holes 33 and 34 in the second direction Y. The cooling medium is introduced from the inlet side manifold 93 into the plurality of groove flow paths 38A through one of the connection portions 38B. Further, the cooling medium flowing through the plurality of groove flow paths 38A is discharged to the outlet side manifold 94 through the other connection portion 38B.

[0032] <Separator 40> As shown in FIGS. 1 and 2, the separator 40 is formed by press-molding a rectangular metal plate made of, for example, titanium or stainless steel in a plan view.

[0033] The separator 40 has through holes 41, 42, 43, 44, 45, 46 that constitute each of the manifolds 91, 92, 93, 94, 95, 96 (see FIG. 1). The separator 40 has a first surface 40A having a facing surface 40a that faces the cathode electrode 13 of the power generation unit 10 in the first direction X, and a second surface 40B having a surface 40b on the side opposite to the facing surface 40a.

[0034] On the first surface 40A, a plurality of groove flow paths 47A through which the oxidant gas flows, a pair of connection parts 47B, and a plurality of ribs 47C that are located between the groove flow paths 47A and project toward the gas diffusion layer 17 of the power generation unit 10 are provided. In FIG. 1, the groove flow paths 47A, the connection parts 47B, and the ribs 47C are shown in a simplified manner.

[0035] The plurality of groove flow paths 47A and the plurality of ribs 47C are provided on the facing surface 40a. The groove flow paths 47A are arranged side by side with a space therebetween in the third direction Z (see FIG. 2). Each of the plurality of groove flow paths 47A extends linearly in the second direction Y (see FIG. 1).

[0036] The ribs 47C are arranged side by side with a space therebetween in the third direction Z (see FIG. 2). Each of the plurality of ribs 47C extends linearly in the second direction Y (see FIG. 1). As shown in FIG. 2, each of the plurality of ribs 47C has a top wall portion 61, a pair of side wall portions 62 located on both sides of the top wall portion 61 in the third direction Z, and a corner portion 63 located between the top wall portion 61 and the side wall portions 62.

[0037] The top wall portion 61 is in contact with the gas diffusion layer 17 of the power generation unit 10. In the present embodiment, the top wall portion 61 is in contact with the gas diffusion layer 17 over the entire rib 47C in the second direction Y.

[0038] The pair of side wall portions 62 are inclined such that the distance between them in the third direction Z increases as they move away from the gas diffusion layer 17 in the first direction X. The corner portion 63 is curved so as to be farther away from the gas diffusion layer 17 in the first direction X as it is farther away from the top wall portion 61 in the third direction Z.

[0039] As shown by the dashed line in FIG. 1, a pair of connection portions 47B extend from both sides of the plurality of groove channels 47A toward the through holes 45 and 46 in the second direction Y. The oxidant gas is introduced from the inlet-side manifold 95 into the plurality of groove channels 47A through one of the connection portions 47B. Further, the oxidant gas flowing through the plurality of groove channels 47A is discharged to the outlet-side manifold 96 through the other connection portion 47B.

[0040] As shown in FIGS. 1 and 2, on the second surface 40B, a plurality of groove channels 48A through which a cooling medium flows, a pair of connection portions 48B, and a plurality of ribs 48C that are located between the groove channels 48A and project toward the side opposite to the rib 47C in the first direction X are provided. In FIG. 1, the groove channels 48A, the connection portions 48B, and the ribs 48C are shown in a simplified manner.

[0041] As shown in FIG. 2, the groove channels 48A are formed by the back side of the rib 47C. Further, the ribs 48C are formed by the back side of the groove channels 47A. As shown in FIG. 1, a pair of connection portions 48B extend from both sides of the plurality of groove channels 48A toward the through holes 43 and 44 in the second direction Y. The cooling medium is introduced from the inlet-side manifold 93 into the plurality of groove channels 48A through one of the connection portions 48B. Further, the cooling medium flowing through the plurality of groove channels 48A is discharged to the outlet-side manifold 94 through the other connection portion 48B.

[0042] <Restriction portions 70, 80> As shown in FIG. 2, the restriction portion 70 is a porous body having conductivity and is provided at a portion facing the groove channel 37A at the corner portion 53.

[0043] The restricting portion 70 is provided on both of a pair of corner portions 53 sandwiching the groove flow path 37A. The restricting portion 70 continuously extends from one of the pair of corner portions 53 along the gas diffusion layer 16 to the other corner portion 53 in the third direction Z.

[0044] The restricting portion 70 is in contact with the gas diffusion layer 16 throughout in the third direction Z. That is, the gap between the corner portion 53 and the gas diffusion layer 16 in the first direction X is filled by the restricting portion 70. In the present embodiment, the restricting portion 70 is provided over the entire groove flow path 37A in the second direction Y.

[0045] The restricting portion 70 is configured to restrict the sinking of the gas diffusion layer 16 into the groove flow path 37A. As shown in FIG. 2, the restricting portion 80 is a porous body having conductivity and is provided at a portion facing the groove flow path 47A at the corner portion 63.

[0046] The restricting portion 80 is provided on both of a pair of corner portions 63 sandwiching the groove flow path 47A. The restricting portion 80 continuously extends from one of the pair of corner portions 63 along the gas diffusion layer 17 to the other corner portion 63 in the third direction Z.

[0047] The restricting portion 80 is in contact with the gas diffusion layer 17 throughout in the third direction Z. That is, the gap between the corner portion 63 and the gas diffusion layer 17 in the first direction X is filled by the restricting portion 80. In the present embodiment, the restricting portion 80 is provided over the entire groove flow path 47A in the second direction Y.

[0048] The restricting portions 70 and 80 are, for example, porous bodies formed from particulate or fibrous conductive members and a resin that binds the conductive members together. As the particulate conductive member, for example, metal materials such as Au (gold), Pt (platinum), Ti (titanium), TiN (titanium nitride), Cu (copper), Co (cobalt), compounds containing the above-described metal materials, or carbon powders such as graphene and graphite can be used.

[0049] As the fibrous conductive member, for example, carbon fibers such as carbon nanotubes and graphite nanofibers can be used. Examples of the resin include thermoplastic resins such as PE (polyethylene), PP (polypropylene), PS (polystyrene), PA (polyamide), PC (polycarbonate), PPE (polyphenylene ether), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PES (polyethersulfone), PPS (polyphenylene sulfide), PPSU (polyphenyl sulfone), PEEK (polyether ether ketone), PI (polyimide), LCP (liquid crystal polymer), COP (cycloolefin polymer), etc., thermosetting resins such as epoxy resins, polymer alloys obtained by combining the above-mentioned resin materials, or fluorine resins such as PTFE (polytetrafluoroethylene), FEP (perfluoroethylene propene copolymer), PFA (perfluoroalkoxy alkane), ETFE (ethylene tetrafluoroethylene copolymer), PVDF (polyvinylidene fluoride), etc. Further, instead of the above-mentioned resin materials, rubber materials such as EPDM (ethylene propylene diene rubber), fluorine-based rubber, and silicon-based rubber can also be used.

[0050] The porosity of the restricting portions 70 and 80 is preferably equal to or greater than the porosity of the gas diffusion layers 16 and 17. Further, the porosity of the restricting portions 70 and 80 is more preferably set to be equal to or greater than the porosity of the gas diffusion layers 16 and 17 within the range of 70% or more. Still more preferably, the porosity of the restricting portions 70 and 80 is set to be equal to or greater than the porosity of the gas diffusion layers 16 and 17 within the range of 70% or more and 80% or less. In the present embodiment, the porosities of the restricting portions 70 and 80 and the gas diffusion layers 16 and 17 are both set to 70%.

[0051] The length L of the restricting portions 70 and 80 in the first direction X is set within the range of 30 μm or more and 150 μm or less. Next, the operation of the present embodiment will be described.

[0052] As shown in FIG. 2, when the separator 30 is vertically downward and a plurality of single cells 90 are stacked, the sinking of the gas diffusion layer 16 into the groove flow path 37A is restricted by the restricting portion 70. Further, according to the configuration of the present embodiment, the restricting portion 70 fills the gap between the corner portion 53 in the first direction X and the gas diffusion layer 16. Therefore, a load acts on the corner portion 53 of the separator 30 from the gas diffusion layer 16 via the restricting portion 70. Further, the restricting portion 80 fills the gap between the corner portion 63 in the first direction X and the gas diffusion layer 17. Therefore, a load acts on the gas diffusion layer 17 from the corner portion 63 of the separator 40 via the restricting portion 80. Thereby, the contact resistance between the separator 30 and the gas diffusion layer 16 and the contact resistance between the separator 40 and the gas diffusion layer 17 are reduced.

[0053] Here, the restricting portions 70 and 80 are porous bodies having conductivity. Therefore, a part of the fuel gas flowing through the groove flow path 37A passes through the inside of the restricting portion 70 and diffuses into the inside of the gas diffusion layer 16. Further, a part of the oxidant gas flowing through the groove flow path 47A passes through the inside of the restricting portion 80 and diffuses into the inside of the gas diffusion layer 17.

[0054] Next, the effects of the present embodiment will be described. (1) The separator 30 has a facing surface 30a facing the power generation unit 10. The facing surface 30a has a plurality of groove flow paths 37A through which fuel gas flows and a plurality of ribs 37C located between the groove flow paths 37A and protruding toward the gas diffusion layer 16 of the power generation unit 10. The plurality of ribs 37C have a top wall portion 51 that contacts the gas diffusion layer 16 of the power generation unit 10, a pair of side wall portions 52 located on both sides of the top wall portion 51 in the third direction Z, and a corner portion 53 located between the top wall portion 51 and the side wall portion 52. A restricting portion 70 for restricting the sinking of the gas diffusion layer 16 into the groove flow path 37A is provided at a portion of the corner portion 53 facing the groove flow path 37A. The restricting portion 70 is a porous body having conductivity.

[0055] According to such a configuration, the above-described operations can be achieved. Therefore, it is possible to suppress the subsidence of the gas diffusion layer 16 into the groove flow path 37A while suppressing the decrease in the diffusibility of the fuel gas. (2) The restricting portion 70 is provided over the entire groove flow path 37A in the second direction Y.

[0056] According to such a configuration, it is possible to suppress the subsidence of the gas diffusion layer 16 into the groove flow path 37A while suppressing the decrease in the diffusibility of the fuel gas over the entire extending direction of the groove flow path 37A. (3) The porosity of the restricting portions 70 and 80 is equal to or greater than the porosity of the gas diffusion layers 16 and 17.

[0057] When the porosity of the restricting portion 70 (80) is lower than the porosity of the gas diffusion layers 16 and 17, when the fuel gas (oxidant gas) flowing in the groove flow path 37A (47A) diffuses into the gas diffusion layer 16 (17), the restricting portion 70 (80) may become an obstacle, resulting in a possible decrease in the diffusibility of the fuel gas (oxidant gas).

[0058] In this regard, according to the above configuration, since the porosity of the restricting portion 70 (80) is equal to or greater than the porosity of the gas diffusion layer 16 (17), a part of the fuel gas (oxidant gas) flowing through the groove flow path 37A (47A) can easily pass through the inside of the restricting portion 70 (80). Thereby, the occurrence of the above-mentioned inconveniences can be suppressed.

[0059] (4) The restricting portions 70 and 80 include particulate or fibrous conductive members and a resin that binds the conductive members together. According to such a configuration, the restricting portions 70 and 80 can be easily formed.

[0060] <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.

[0061] · The shapes of the inlet-side manifolds 91, 93, 95 and the outlet-side manifolds 92, 94, 96 are not limited to the rectangular shape in plan view as exemplified in this embodiment. For example, the shapes of the manifolds 91, 92, 93, 94, 95, 96 may be a quadrangular shape in plan view including a square or the like, or may be a polygonal shape in plan view including a triangle, a pentagon, or the like. Further, it may be a circular shape in plan view including an ellipse, an oblong, or the like.

[0062] · The flows of the reaction gas and the cooling medium in the manifolds 91, 92, 93, 94, 95, 96 are not limited to those exemplified in the above embodiment. For example, the manifold 96 may be an inlet-side manifold for the oxidant gas, and the manifold 95 may be an outlet-side manifold for the oxidant gas. Further, accordingly, the manifold 94 may be an inlet-side manifold for the cooling medium, and the manifold 93 may be an outlet-side manifold for the cooling medium. That is, the oxidant gas flowing through the groove flow path 47A and the cooling medium flowing through the groove flow paths 38A, 48A may flow in the same direction as the fuel gas flowing through the groove flow path 37A.

[0063] · The groove flow path 37A (38A) is not limited to extending linearly in the second direction Y as exemplified in the above embodiment. For example, the groove flow path 37A (38A) may extend in a wave shape in the surface direction of the opposing surface 30a (surface 30b). In this case, the rib 37C (rib 38C) extends in a wave shape in the surface direction of the opposing surface 30a (surface 30b).

[0064] · The groove flow path 47A (48A) is not limited to extending linearly in the second direction Y as exemplified in the above embodiment. For example, the groove flow path 47A (48A) may extend in a wave shape in the surface direction of the opposing surface 40a (surface 40b). In this case, the rib 47C (rib 48C) extends in a wave shape in the surface direction of the opposing surface 40a (surface 40b).

[0065] · The shape of rib 37C is not limited to that exemplified in this embodiment. For example, the pair of side wall portions 52 are not limited to being inclined as exemplified in this embodiment, and may be orthogonal to the top wall portion 51. Further, the corner portion 53 is not limited to being curved as exemplified in this embodiment, and may be provided between the side wall portion 52 that bends and extends from the top wall portion 51 and the top wall portion 51.

[0066] · The shape of rib 47C is not limited to that exemplified in this embodiment. For example, the pair of side wall portions 62 are not limited to being inclined as exemplified in this embodiment, and may be orthogonal to the top wall portion 61. Further, the corner portion 63 is not limited to being curved as exemplified in this embodiment, and may be provided between the side wall portion 62 that bends and extends from the top wall portion 61 and the top wall portion 61.

[0067] · The restricting portions 70 and 80 are not limited to having a resin that bonds conductive members as exemplified in this embodiment. For example, the restricting portions 70 and 80 may be formed only by conductive members.

[0068] · The restricting portion 70 is not limited to continuously extending from one of the pair of corner portions 53 that sandwich the groove flow path 37A in the third direction Z along the gas diffusion layer 16 to the other corner portion 53 as exemplified in this embodiment. For example, the restricting portion 70 may be provided only at the corner portion 53. Specifically, as shown in FIG. 3, between the groove flow path 37A and the gas diffusion layer 16, the restricting portion 70 may be provided at intervals in the third direction Z with respect to both the one corner portion 53 and the other corner portion 53.

[0069] According to such a configuration, the material required for the restricting portion 70 can be reduced. · As exemplified in the present embodiment, the restricting portion 80 is not limited to being continuously extended from one of a pair of corner portions 63 sandwiching the groove flow path 47A in the third direction Z to the other corner portion 63 along the gas diffusion layer 17. For example, the restricting portion 80 may be provided only at the corner portion 63. Specifically, as shown in FIG. 3, between the groove flow path 47A and the gas diffusion layer 17, the restricting portion 80 may be provided so as to be spaced apart from each other in the third direction Z with respect to both the one corner portion 63 and the other corner portion 63.

[0070] According to such a configuration, the material required for the restricting portion 80 can be reduced. · The porosity of the restricting portions 70 and 80 is not limited to 70% exemplified in the present embodiment, and may be appropriately changed as long as it is equal to or higher than the porosity of the gas diffusion layers 16 and 17. Further, the porosity of the restricting portions 70 and 80 may be set to be less than the porosity of the gas diffusion layers 16 and 17 as long as the effects of the present embodiment are achieved.

[0071] · The restricting portion 70 is not limited to being provided over the entire groove flow path 37A in the second direction Y, and a plurality of restricting portions 70 may be provided at intervals in the second direction Y.

[0072] · The restricting portion 80 is not limited to being provided over the entire groove flow path 47A in the second direction Y, and a plurality of restricting portions 80 may be provided at intervals in the second direction Y.

[0073] · The single cell 90 is not limited to being stacked with the separator 30 facing vertically downward as exemplified in the present embodiment, and may be stacked with the separator 40 facing vertically downward.

[0074] According to such a configuration, the sinking of the gas diffusion layer 17 into the groove flow path 47A is regulated by the regulating portion 80. Also, at this time, since the regulating portion 80 is a porous body having conductivity, a part of the oxidant gas flowing through the groove flow path 47A passes through the inside of the regulating portion 80 and diffuses into the inside of the gas diffusion layer 17. Therefore, it is possible to suppress the sinking of the gas diffusion layer 17 into the groove flow path 47A while suppressing a decrease in the diffusibility of the oxidant gas.

[0075] · The separators 30 and 40 are not limited to those formed by press-molding a metal plate material, and can also be formed by, for example, cutting or etching. · The material of the separators 30 and 40 is not limited to titanium or stainless steel, and aluminum can also be used. Further, a material other than metal such as carbon may be used.

Explanation of Reference Numerals

[0076] L... Length X... First direction Y... Second direction Z... Third direction 10... Power generation unit 11... Electrolyte membrane 12... Anode electrode 13... Cathode electrode 14... Catalyst layer 15... Catalyst layer 16... Gas diffusion layer 17... Gas diffusion layer 20... Frame member 21... Through hole 22... Through hole 23... Through hole 24... Through hole 25... Through hole 26... Through hole 27... Opening 30... Separator 30A... First surface 30a... Opposing surface 30B... Second surface 30b... Surface 31... Through hole 32... Through hole 33... Through hole 34…Through-hole 35…Through-hole 36…Through-hole 37A…Groove flow path 37B…Connection part 37C…Rib 38A…Groove flow path 38B…Connection part 38C…Rib 40…Separator 40A…First surface 40a…Opposite surface 40B…Second surface 40b…Surface 41…Through-hole 42…Through-hole 43…Through-hole 44…Through-hole 45…Through-hole 46…Through-hole 47A…Groove flow path 47B…Connection part 47C…Rib 48A…Groove flow path 48B…Connection part 48C…Rib 51…Top wall part 52…Side wall part 53…Corner part 61…Top wall part 62…Side wall part 63…Corner part 70…Restriction part 80…Restriction part 90…Single cell 91…Inlet side manifold 92…Outlet side manifold 93…Inlet side manifold 94…Outlet side manifold 95…Inlet side manifold 96…Outlet side manifold

Claims

1. A power generation unit having a membrane electrode assembly and a pair of gas diffusion layers sandwiching the membrane electrode assembly, and a pair of separators sandwiching the power generation unit, wherein the pair of separators has a facing surface facing the power generation unit, the facing surface has a plurality of groove flow paths through which a reaction gas flows and a plurality of ribs located between the groove flow paths and protruding toward the power generation unit, the plurality of ribs have a top wall portion that contacts the power generation unit, a pair of side wall portions located on both sides of the top wall portion in the arrangement direction of the plurality of groove flow paths, and a corner portion located between the top wall portion and the side wall portion, a regulating portion for regulating the sinking of the gas diffusion layer into the groove flow path is provided at a portion of the corner portion facing the groove flow path, the regulating portion is a porous body having conductivity, A single cell of a fuel cell.

2. The regulating portion is provided over the entire groove flow path in the extending direction of the groove flow path. The single cell of a fuel cell according to Claim 1.

3. The porosity of the regulating portion is equal to or greater than the porosity of the gas diffusion layer. The single cell of a fuel cell according to Claim 1 or Claim 2.

4. The regulating portion is provided only at the corner portion. The single cell of a fuel cell according to any one of Claims 1 to 3.

5. The regulating portion has a particulate or fibrous conductive member and a resin that binds the conductive members together. The single cell of a fuel cell according to any one of Claims 1 to 4.

Images