JP2014038750A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell that favorably reduces accumulated water in a separator surface, and allows stable power generation, with a simple configuration.SOLUTION: A fuel cell 10 includes power generation cells 12, each having a membrane electrode assembly 16 sandwiched between a first metal separator 18 and a second metal separator 20. The first metal separator 18 has first protrusions 38a(e) in upper and lower portions thereof in a direction of gravitational force, and second protrusions 38a(c) in a central portion thereof in the direction of gravitational force. First contact area per unit area between each first protrusion 38a(e) and the membrane electrode assembly 16 is smaller than second contact area per unit area between each second protrusion 38a(c) and the membrane electrode assembly 16.

Description

  The present invention relates to a fuel cell in which an electrolyte membrane / electrode structure provided with electrodes on both sides of a solid polymer electrolyte membrane and a horizontally elongated metal separator are stacked in a horizontal position in a standing posture.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) provided with an anode electrode and a cathode electrode on both sides of a solid polymer electrolyte membrane made of a polymer ion exchange membrane is formed by a pair of separators. The sandwiched power generation cell is configured. A fuel cell is normally used as an in-vehicle fuel cell system by stacking a plurality of power generation cells to form a fuel cell stack and being incorporated in a fuel cell vehicle for in-vehicle use in addition to stationary use.

  In the above fuel cell, a fuel gas channel (hereinafter also referred to as a reaction gas channel) for flowing a fuel gas to the anode electrode and an oxidant gas for flowing an oxidant gas to the cathode electrode in the plane of the separator A flow path (hereinafter also referred to as a reaction gas flow path) is provided. Furthermore, a cooling medium flow path for flowing the cooling medium is provided along the surface direction of the separator for each power generation cell or for each of the plurality of power generation cells.

  By the way, in the plane of the separator, the temperature in the vicinity of the center of the reaction gas channel tends to increase due to the flow of the cooling medium, heat radiation to the outside, and the like. For this reason, for example, in the fuel cell disclosed in Patent Document 1, an oxidant gas flow path 2 is provided in the oxidant gas separator 1 as shown in FIG.

  The oxidant gas flow path 2 has a plurality of oxidant gas flow path grooves 2b formed between a plurality of rib portions 2a extending in the horizontal direction. The oxidant gas flow path 2 communicates with the oxidant gas supply manifold 3a and the oxidant gas discharge manifold 3b. Each of the oxidant gas flow channel grooves 2b has a larger cross-sectional area from the end in the separator surface to the center. This prevents the mass flow rate of the oxidant gas flowing near the center of the oxidant gas flow path 2 from being lowered.

JP 2005-174648 A

  In the oxidant gas separator 1 described above, the relative humidity in the portion where there is a large amount of refrigerant distribution and external heat dissipation, that is, the lower and upper direction of gravity of the oxidant gas flow path 2 is high in low load operation and low humidification operation. . For this reason, the generated water tends to increase because the membrane resistance decreases and the reaction concentrates. Therefore, there is a problem that the staying water regions 4a and 4b in which droplets (water) stay are present in the separator surface.

  In particular, in Patent Document 1, the interval between the rib portions 2a below and above the oxidant gas flow path 2 in the gravity direction is set smaller than the distance between the rib portions 2a at the center of the oxidant gas flow path 2 in the gravity direction. Has been. As a result, the contact area between the rib portion 2a and the electrolyte membrane / electrode structure (not shown) is lower and higher in the gravity direction of the oxidant gas flow channel 2 than in the gravity direction center of the oxidant gas flow channel 2. There is a problem that the contact resistance is lowered and the generated water is further increased.

  The present invention solves this type of problem, and provides a fuel cell capable of reducing the accumulated water in the separator surface with a simple configuration and capable of performing stable power generation. With the goal.

  In the present invention, an electrolyte membrane / electrode structure in which electrodes are respectively provided on both sides of a solid polymer electrolyte membrane, and a horizontally long metal separator formed by corrugating a metal plate, are in a standing posture along the horizontal direction. A fuel that is stacked and has a reaction gas flow path that circulates a reaction gas that is an oxidant gas or a fuel gas along the horizontal direction, provided between the convex portions of the metal separator that contacts the electrolyte membrane / electrode structure. It relates to batteries.

  The metal separator is provided with a reaction gas supply port for supplying a reaction gas to the reaction gas channel at one end in the horizontal direction, and a reaction gas discharge port for discharging the reaction gas from the reaction gas channel at the other end in the horizontal direction. ing. And the 1st contact area per unit area of the 1st convex part which is a convex part provided in the gravity direction upper part and the lower part of a metal separator, and an electrolyte membrane electrode structure is provided in the gravity direction center of the metal separator. It is smaller than the 2nd contact area per unit area of the 2nd convex part which is the said convex part, and the said electrolyte membrane and electrode structure.

  Further, in this fuel cell, the vertical width dimension of the first convex portion contacting the electrolyte membrane / electrode structure is larger than the vertical dimension of the second convex portion contacting the electrolyte membrane / electrode structure. Small is preferable.

  Further, in this fuel cell, the metal separator is subjected to a gold plating process on the contact portion with the electrolyte membrane / electrode structure, and the gold plating amount of the first contact portion set to the first contact area is the second contact amount. The amount is preferably smaller than the gold plating amount of the second contact portion set to the area.

  Furthermore, in this fuel cell, it is preferable that the spacing between the first protrusions is greater than the spacing between the second protrusions.

  In this fuel cell, the metal separator has a reaction gas supply port for supplying a reaction gas to the reaction gas channel at one end in the horizontal direction, and discharges the reaction gas from the reaction gas channel at the other end in the horizontal direction. The spacing between the first protrusions, which are the protrusions provided above and below the gravity direction of the metal separator, is provided in the center of the metal separator in the gravity direction. This is larger than the spacing between the second convex portions.

  In this invention, the 1st contact area of the gravity direction upper direction and the downward direction of a metal separator is set smaller than the 2nd contact area of the gravity direction center of the said metal separator. Moreover, the separation interval between the first protrusions is set to be larger than the separation interval between the second protrusions.

  For this reason, the contact resistance with the electrolyte membrane / electrode structure is increased above and below the gravity direction of the metal separator as compared with the center in the gravity direction, and the power generation density is reduced. Accordingly, since the amount of generated water is reduced, the generation of droplets can be satisfactorily suppressed. Thereby, with a simple structure, the stagnant water in a separator surface can be reduced favorably, and it becomes possible to perform stable electric power generation.

It is a disassembled perspective explanatory drawing of the electric power generation cell which comprises the fuel cell which concerns on the 1st Embodiment of this invention. It is the II-II sectional view taken on the line of the said electric power generation cell in FIG. It is front explanatory drawing of the 1st metal separator which comprises the said electric power generation cell. It is a disassembled perspective explanatory drawing of the electric power generation cell which comprises the fuel cell which concerns on the 2nd Embodiment of this invention. It is the VV sectional view taken on the line of FIG. 4 of the said electric power generation cell. It is front explanatory drawing of the 1st metal separator which comprises the said electric power generation cell. It is front explanatory drawing of the oxidant gas separator which comprises the fuel cell disclosed by patent document 1. FIG.

  As shown in FIGS. 1 and 2, in the fuel cell 10 according to the first embodiment of the present invention, a plurality of power generation cells 12 are stacked in the horizontal direction (arrow A direction) in a standing posture.

  The power generation cell 12 includes an electrolyte membrane / electrode structure (MEA) 16 and horizontally elongated first metal separator 18 and second metal separator 20 that sandwich the electrolyte membrane / electrode structure 16. The first metal separator 18 and the second metal separator 20 have a concavo-convex shape by pressing a thin metal plate into a wave shape, a dimple shape, or the like (see FIG. 2).

  An oxidant gas supply for supplying an oxidant gas, for example, an oxygen-containing gas, to one end edge of the power generation cell 12 in the long side direction (the arrow B direction in FIG. 1) in communication with the arrow A direction. A communication hole 26a, a cooling medium supply communication hole 28a for supplying a cooling medium, and a fuel gas discharge communication hole 30b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided.

  The other end edge in the long side direction of the power generation cell 12 communicates with each other in the direction of the arrow A, the fuel gas supply communication hole 30a for supplying fuel gas, and the cooling medium discharge communication hole for discharging the cooling medium. 28b, and an oxidant gas discharge communication hole 26b for discharging the oxidant gas.

  As shown in FIG. 3, on the surface 18a of the first metal separator 18 facing the electrolyte membrane / electrode structure 16, an oxidant gas flow communicating the oxidant gas supply communication hole 26a and the oxidant gas discharge communication hole 26b. A passage (reaction gas passage) 38 is formed. The oxidant gas flow path 38 has, for example, a plurality of convex portions 38a extending in the direction of arrow B (horizontal direction) and in contact with the electrolyte membrane / electrode structure 16, and a plurality of convex portions 38a formed between the convex portions 38a. And an oxidant gas flow path groove 38b.

  The first contact area per unit area between the first protrusion 38 a (e) provided above and below the first metal separator 18 in the direction of gravity and the electrolyte membrane / electrode structure 16 is determined by the first metal separator 18. It is set smaller than the second contact area per unit area between the second convex portion 38a (c) provided at the center in the direction of gravity and the electrolyte membrane / electrode structure 16.

  Specifically, as shown in FIGS. 2 and 3, the width dimension (dimension in the direction of arrow C) h1 of the first protrusion 38a (e) is the width dimension (arrow C) of the second protrusion 38a (c). (Dimension in direction) is set to a size smaller than h2 (h1 <h2). A predetermined number of first protrusions 38a (e) are provided in the vertical direction. That is, the number of the first protrusions 38 a (e) can be set corresponding to the upper and lower stagnant water generation regions of the oxidant gas flow path 38. In addition, you may set to a large dimension in steps from the width dimension h1 to the width dimension h2 from the outer side to the inner side.

  A first gold plating layer 39a is provided on the first protrusion 38a (e), which is the first contact site set to the first contact area, and the second contact site is set to the second contact area. A second gold plating layer 39b is provided on the two convex portions 38a (c). As shown in FIG. 2, the gold plating amount per unit area of the first gold plating layer 39a is set smaller than the gold plating amount of the second gold plating layer 39b.

  As shown in FIG. 3, an inlet buffer portion 40 a having a plurality of embosses 40 ae is provided on the inlet side of the oxidant gas flow path 38, and a plurality of embossments are provided on the outlet side of the oxidant gas flow path 38. An outlet buffer portion 40b having 40be is provided.

  As shown in FIG. 1, a fuel gas flow path (reaction) that connects a fuel gas supply communication hole 30 a and a fuel gas discharge communication hole 30 b to the surface 20 a of the second metal separator 20 facing the electrolyte membrane / electrode structure 16. Gas channel) 42 is formed. The fuel gas channel 42 has, for example, a plurality of convex portions 42a extending in the direction of arrow B, and a plurality of fuel gas channel grooves 42b formed between the convex portions 42a.

  The first contact area per unit area between the first convex portion 42a (e) provided above and below the gravity direction of the second metal separator 20 and the electrolyte membrane / electrode structure 16 is determined by the second metal separator 20. It is set to be smaller than the second contact area per unit area between the second convex portion 42a (c) provided at the center in the gravity direction and the electrolyte membrane / electrode structure 16.

  Specifically, as shown in FIG. 2, the width dimension (dimension in the direction of arrow C) h3 of the first protrusion 42a (e) is smaller than the width dimension h4 of the second protrusion 42a (c). It is set (h3 <h4). A predetermined number of first protrusions 42a (e) are provided in the vertical direction. That is, the number of the first protrusions 42a (e) can be set corresponding to the accumulated water generation regions at the upper and lower portions of the fuel gas flow path 42. In addition, from the outside toward the inside, the width dimension h3 may be set to a large dimension stepwise from the width dimension h3.

  A first gold plating layer 39c is provided on the first convex portion 42a (e) which is a first contact portion set to the first contact area, and a second contact portion which is set to the second contact area. The second convex portion 42a (c) is provided with a second gold plating layer 39d. As shown in FIG. 2, the gold plating amount per unit area of the first gold plating layer 39c is set to be smaller than the gold plating amount of the second gold plating layer 39d.

  As shown in FIG. 2, the first metal separator 18 and the second metal separator 20 are stacked with the electrolyte membrane / electrode structure 16 sandwiched therebetween, and the first protrusion 38a (e) and the first protrusion The portions 42a (e) overlap with each other in the stacking direction.

  As shown in FIG. 1, an inlet buffer 43a having a plurality of embosses 43ae is provided on the inlet side of the fuel gas passage 42, and a plurality of embosses 43be are provided on the outlet side of the fuel gas passage 42. An outlet buffer 43b is provided. The electrolyte membrane / electrode structure 16 is sandwiched between the embosses 40ae, 40be and 43be, 43ae from both sides. The same applies to the second embodiment described below.

  Between the surface 18b of the first metal separator 18 and the surface 20b of the second metal separator 20, a cooling medium flow path 44 that connects the cooling medium supply communication hole 28a and the cooling medium discharge communication hole 28b is integrally formed. Is done. The cooling medium flow path 44 is configured by overlapping the back surface shapes of the oxidant gas flow path 38 and the fuel gas flow path 42.

  A first seal member 46 is integrally formed on the surfaces 18 a and 18 b of the first metal separator 18 around the outer peripheral end of the first metal separator 18. A second seal member 48 is integrally formed on the surfaces 20 a and 20 b of the second metal separator 20 around the outer peripheral end of the second metal separator 20.

  The first seal member 46 and the second seal member 48 are, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, or acrylic rubber, or a cushion material. Alternatively, an elastic seal member such as a packing material is used.

  As shown in FIGS. 1 and 3, the first seal member 46 has a flat seal portion 46a formed on the surfaces 18a and 18b with a uniform thickness. The first seal member 46 protrudes from the flat seal portion 46a on the surface 18a side, and has a convex seal portion 46b that communicates the oxidant gas supply communication hole 26a, the oxidant gas discharge communication hole 26b, and the oxidant gas flow path 38. (See FIG. 3).

  The first seal member 46 has a convex seal portion 46c that protrudes from the flat seal portion 46a on the surface 18b side and communicates the cooling medium supply communication hole 28a, the cooling medium discharge communication hole 28b, and the cooling medium flow path 44 (see FIG. 1).

  The second seal member 48 has a flat seal portion 48a formed with a uniform thickness on the surfaces 20a and 20b. The second seal member 48 has a convex seal portion 48 b that protrudes from the flat seal portion 48 a on the surface 20 a side and communicates the fuel gas supply communication hole 30 a and the fuel gas discharge communication hole 30 b with the fuel gas passage 42.

  As shown in FIG. 2, the electrolyte membrane / electrode structure 16 includes, for example, a solid polymer electrolyte membrane 50 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode electrode sandwiching the solid polymer electrolyte membrane 50 52 and an anode electrode 54. The solid polymer electrolyte membrane 50 is set to have a larger surface area than the cathode electrode 52 and the anode electrode 54, and the outer peripheral edge protrudes outward from the outer peripheral ends of the cathode electrode 52 and the anode electrode 54.

  In the cathode electrode 52 and the anode electrode 54, gas diffusion layers 52a and 54a made of carbon paper or the like, and porous carbon particles carrying a platinum alloy on the surface are uniformly applied to the surfaces of the gas diffusion layers 52a and 54a. Electrode catalyst layers 52b and 54b.

  The electrode catalyst layers 52b and 54b are formed on both surfaces of the solid polymer electrolyte membrane 50, and the outer peripheral ends of the electrode catalyst layers 52b and 54b are the protrusions of the first metal separator 18 and the protrusions of the second metal separator 20, respectively. It is pinched by. The same applies to the second embodiment described below.

  The operation of the fuel cell 10 configured as described above will be described below.

  As shown in FIG. 1, in the fuel cell 10, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 26a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply communication hole 30a. Supplied. Further, a coolant such as pure water or ethylene glycol is supplied to the coolant supply passage 28a. For this reason, in each power generation cell 12, the oxidant gas, the fuel gas, and the cooling medium are supplied in the direction of arrow A, respectively.

  As shown in FIG. 3, the oxidant gas is introduced into the oxidant gas flow path 38 of the first metal separator 18 through the oxidant gas supply communication hole 26 a, and along the cathode electrode 52 of the electrolyte membrane / electrode structure 16. Moving. On the other hand, as shown in FIG. 1, the fuel gas is introduced into the fuel gas flow path 42 of the second metal separator 20 through the fuel gas supply communication hole 30a and moves along the anode electrode 54 of the electrolyte membrane / electrode structure 16. To do.

  Therefore, in each electrolyte membrane / electrode structure 16, the oxidant gas supplied to the cathode electrode 52 and the fuel gas supplied to the anode electrode 54 are consumed by an electrochemical reaction in the electrode catalyst layers 52b and 54b. Power generation is performed.

  Next, the oxidant gas consumed by being supplied to the cathode electrode 52 is discharged to the oxidant gas discharge communication hole 26b and flows in the direction of arrow A. Similarly, the fuel gas consumed by being supplied to the anode electrode 54 is discharged to the fuel gas discharge communication hole 30b and flows in the direction of arrow A.

  The cooling medium flows through the cooling medium supply communication hole 28a into the cooling medium flow path 44 between the first metal separator 18 and the second metal separator 20 and then flows along the arrow B direction. The cooling medium cools the electrolyte membrane / electrode structure 16, and then moves through the cooling medium discharge communication hole 28 b and is discharged from the fuel cell 10.

  In this case, in the first embodiment, as shown in FIGS. 2 and 3, the first protrusion 38 a (e) and the electrolyte membrane / electrode structure provided above and below the gravity direction of the first metal separator 18. The first contact area per unit area with the first metal separator 18 per unit area between the second convex portion 38a (c) provided in the center of the gravity direction of the first metal separator 18 and the electrolyte membrane / electrode structure 16 is as follows. It is set smaller than the second contact area.

  For this reason, the contact resistance value with the electrolyte membrane / electrode structure 16 is increased and the power generation density is decreased, particularly in the upper and lower direction of the first metal separator 18 where droplets are likely to be generated, compared to the center in the direction of gravity. . Accordingly, in the plane of the first metal separator 18, the amount of generated water above and below the direction of gravity decreases, so that the generation of droplets can be satisfactorily suppressed.

  Moreover, the gold plating amount of the first gold plating layer 39a provided on the first protrusion 38a (e) is set to be smaller than the gold plating amount of the second gold plating layer 39b provided on the second protrusion 38a (c). That is, the contact resistance value can be increased by reducing the amount of gold plating.

  Thereby, with the simple structure, the stagnant water in the separator surface of the 1st metal separator 18 can be reduced favorably, and the effect that it becomes possible to perform stable electric power generation is acquired.

  On the other hand, the first contact area per unit area between the first convex portion 42a (e) provided above and below the gravity direction of the second metal separator 20 and the electrolyte membrane / electrode structure 16 is the second metal separator. 20 is set to be smaller than the second contact area per unit area between the second convex portion 42a (c) provided at the center in the gravity direction and the electrolyte membrane / electrode structure 16.

  Moreover, the gold plating amount of the first gold plating layer 39c provided on the first protrusion 42a (e) is set to be smaller than the gold plating amount of the second gold plating layer 39d provided on the second protrusion 42a (c). That is, the contact resistance value can be increased by reducing the amount of gold plating.

  For this reason, in the surface of the second metal separator 20, the amount of water produced above and below the direction of gravity where droplets are particularly likely to decrease is reduced, and the generation of droplets can be suppressed satisfactorily. Thereby, with the simple structure, the retained water in the separator surface of the 2nd metal separator 20 can be reduced favorably, and the effect that it becomes possible to perform stable electric power generation is acquired.

  FIG. 4 is an exploded perspective view of the power generation cell 62 constituting the fuel cell 60 according to the second embodiment of the present invention. The same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The power generation cell 62 includes an electrolyte membrane / electrode structure 16, and horizontally long first metal separators 64 and second metal separators 66 that sandwich the electrolyte membrane / electrode structure 16 (see FIGS. 4 and 5). .

  As shown in FIG. 6, on the surface 64a of the first metal separator 64 facing the electrolyte membrane / electrode structure 16, an oxidant gas flow communicating the oxidant gas supply communication hole 26a and the oxidant gas discharge communication hole 26b. A passage (reaction gas passage) 68 is formed. The oxidant gas flow path 68 includes, for example, a plurality of protrusions 68a extending in the direction of arrow B (horizontal direction) and in contact with the electrolyte membrane / electrode structure 16, and a plurality of protrusions 68a formed between the protrusions 68a. And an oxidant gas flow path groove 68b.

  The first contact area per unit area between the first protrusion 68 a (e) provided above and below the first metal separator 64 in the gravity direction and the electrolyte membrane / electrode structure 16 is determined by the first metal separator 64. It is set smaller than the second contact area per unit area between the second convex portion 68a (c) provided at the center in the direction of gravity and the electrolyte membrane / electrode structure 16.

  Specifically, as shown in FIGS. 5 and 6, the separation interval (interval in the direction of arrow C) S1 between the first protrusions 68a (e) is the separation interval S2 between the second protrusions 68a (c). Larger dimension (S2 <S1). A predetermined number of first protrusions 68a (e) are provided in the vertical direction. That is, the number of first protrusions 68a (e) can be set corresponding to the upper and lower stagnant water generation regions of the oxidant gas flow path 68. In addition, from the outside toward the inside, the width dimension h1 may be set to a small dimension stepwise from the width dimension h1.

  As shown in FIG. 4, the surface 66a of the second metal separator 66 facing the electrolyte membrane / electrode structure 16 has a fuel gas flow path (reaction) communicating with the fuel gas supply communication hole 30a and the fuel gas discharge communication hole 30b. Gas channel) 70 is formed. The fuel gas flow path 70 includes, for example, a plurality of protrusions 70a extending in the direction of arrow B (horizontal direction) and contacting the electrolyte membrane / electrode structure 16, and a plurality of protrusions 70a formed between the protrusions 70a. And a fuel gas channel groove 70b.

  The first contact area per unit area between the first protrusion 70a (e) provided above and below the second metal separator 66 in the direction of gravity and the electrolyte membrane / electrode structure 16 is determined by the second metal separator 66. It is set smaller than the second contact area per unit area between the second convex portion 70a (c) provided at the center in the direction of gravity and the electrolyte membrane / electrode structure 16.

  Specifically, as shown in FIGS. 4 and 5, the separation interval (interval in the direction of arrow C) S3 between the first protrusions 70a (e) is the separation interval S4 between the second protrusions 70a (c). Larger dimension (S4 <S3). A predetermined number of first protrusions 70a (e) are provided in the vertical direction. That is, the number of the first protrusions 70 a (e) can be set corresponding to the upper and lower stagnant water generation regions of the fuel gas channel 70. In addition, from the outside toward the inside, the width dimension h3 may be set to a small dimension stepwise from the width dimension h3.

  A cooling medium flow path 44 is formed between the surface 64 b of the first metal separator 64 and the surface 66 b of the second metal separator 66 adjacent to each other.

  In the second embodiment configured as described above, as shown in FIGS. 5 and 6, in the first metal separator 64, the separation interval S <b> 1 between the first protrusions 68 a (e) is the second protrusion 68 a. (C) The dimension is set to be larger than the distance S2 between them. For this reason, the first contact area per unit area between the first convex portion 68a (e) and the electrolyte membrane / electrode structure 16 is the same as that between the second convex portion 68a (c) and the electrolyte membrane / electrode structure 16. It is set smaller than the second contact area per unit area.

  Therefore, particularly in the upper and lower direction of the first metal separator 64 where droplets are likely to be generated, the contact resistance value with the electrolyte membrane / electrode structure 16 increases and the power generation density decreases compared to the center in the direction of gravity.

  Similarly, in the second metal separator 66, as shown in FIG. 5, the spacing S3 between the first protrusions 70a (e) is larger than the spacing S4 between the second protrusions 70a (c). Is set. As a result, the first contact area per unit area between the first convex portion 70a (e) and the electrolyte membrane / electrode structure 16 is the same as that between the second convex portion 70a (c) and the electrolyte membrane / electrode structure 16. It is set smaller than the second contact area per unit area.

  For this reason, the contact resistance value with the electrolyte membrane / electrode structure 16 increases and the power generation density decreases particularly above and below the gravity direction of the second metal separator 66 where droplets are likely to be generated. Therefore, in the second embodiment, the same effect as in the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 10, 60 ... Fuel cell 12, 62 ... Power generation cell 16 ... Electrolyte membrane and electrode structure 18, 20, 64, 66 ... Metal separator 26a ... Oxidant gas supply communication hole 26b ... Oxidant gas discharge communication hole 28a ... Cooling medium Supply communication hole 28b ... Cooling medium discharge communication hole 30a ... Fuel gas supply communication hole 30b ... Fuel gas discharge communication hole 38, 68 ... Oxidant gas flow path 38a, 38a (c), 38a (e), 42a, 42a (c) ), 42a (e), 68a, 68a (c), 68a (e), 70a, 70a (c), 70a (e) ... convex portions 38b, 68b ... oxidant gas flow path grooves 39a to 39d ... gold plating layer 42 , 70 ... Fuel gas passage 42b, 70b ... Fuel gas passage groove 44 ... Cooling medium passage 46, 48 ... Seal member 50 ... Solid polymer electrolyte membrane 52 ... Cathode electrode 54 ... Anode electrode

Claims (5)

An electrolyte membrane / electrode structure in which electrodes are provided on both sides of a solid polymer electrolyte membrane and a horizontally long metal separator formed by corrugating a metal plate are stacked in a horizontal position in a standing position. A fuel cell in which a reaction gas flow path for flowing a reaction gas that is an oxidant gas or a fuel gas along a horizontal direction is provided between convex portions of the metal separator in contact with the electrolyte membrane / electrode structure, ,
The metal separator has a reaction gas supply port for supplying the reaction gas to the reaction gas channel at one end in the horizontal direction, and a reaction gas exhaust for discharging the reaction gas from the reaction gas channel at the other end in the horizontal direction. While providing an exit,
The first contact area per unit area between the first convex portion, which is the convex portion provided above and below the metal separator in the gravity direction, and the electrolyte membrane / electrode structure is at the center of the metal separator in the gravity direction. A fuel cell, characterized in that it is smaller than a second contact area per unit area between the provided second convex portion, which is the convex portion, and the electrolyte membrane / electrode structure.   2. The fuel cell according to claim 1, wherein a width dimension in a vertical direction in contact with the electrolyte membrane / electrode structure of the first convex portion is a vertical direction in contact with the electrolyte membrane / electrode structure of the second convex portion. A fuel cell, characterized in that it is smaller than the width dimension. 3. The fuel cell according to claim 1, wherein the metal separator is subjected to a gold plating treatment at a contact portion with the electrolyte membrane / electrode structure,
The fuel cell according to claim 1, wherein a gold plating amount of the first contact portion set to the first contact area is smaller than a gold plating amount of the second contact portion set to the second contact area.   2. The fuel cell according to claim 1, wherein the spacing between the first protrusions is greater than the spacing between the second protrusions. An electrolyte membrane / electrode structure in which electrodes are provided on both sides of a solid polymer electrolyte membrane and a horizontally long metal separator formed by corrugating a metal plate are stacked in a horizontal position in a standing position. A fuel cell in which a reaction gas flow path for flowing a reaction gas that is an oxidant gas or a fuel gas along a horizontal direction is provided between convex portions of the metal separator in contact with the electrolyte membrane / electrode structure, ,
The metal separator has a reaction gas supply port for supplying the reaction gas to the reaction gas channel at one end in the horizontal direction, and a reaction gas exhaust for discharging the reaction gas from the reaction gas channel at the other end in the horizontal direction. While providing an exit,
The spacing between the first protrusions that are the protrusions provided above and below the gravity direction of the metal separator is the distance between the second protrusions that are the protrusions provided at the center of the metal separator in the gravity direction. A fuel cell characterized by being larger than the separation interval.

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