JP4664097B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell having an electrolyte / electrode structure configured by sandwiching an electrolyte between a pair of electrodes, and alternately stacking the electrolyte / electrode structure and a separator.

  For example, a solid polymer fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. In this fuel cell, an electrolyte membrane / electrode structure (electrolyte / electrode structure) in which an anode side electrode and a cathode side electrode each made of an electrode catalyst and porous carbon are provided on both sides of a solid polymer electrolyte membrane is separated into a separator. It is configured by being sandwiched between (bipolar plates). Usually, a fuel cell stack in which a predetermined number of the fuel cells are stacked is used.

  In the above fuel cell, a fuel gas channel (reactive gas channel) for flowing a fuel gas opposite to the anode side electrode and an oxidant gas for flowing the cathode gas facing the cathode side electrode in the plane of the separator. The oxidant gas flow path (reaction gas flow path) is provided. Further, between the separators, a cooling medium flow path for flowing the cooling medium is provided along the surface direction of the separator.

  In general, a fuel cell is provided with a channel inlet communication hole and a channel outlet communication hole that penetrate in the stacking direction of the separator. The fuel gas, the oxidant gas, and the cooling medium are supplied to the fuel gas flow path, the oxidant gas flow path, and the cooling medium flow path from the respective flow path inlet communication holes, and then to the respective flow path outlet communication holes. It is discharged.

  By the way, when air is mixed in the cooling medium supplied to the cooling medium flow path and when the cooling medium is injected after the fuel cell is assembled, the air moves to the upper area of the cooling medium flow path and remains. There is a risk. As a result, a space that does not have a cooling function exists in the upper part of the cooling medium flow path, and it is pointed out that the entire power generation surface of the fuel cell cannot be cooled well and uniformly.

  Therefore, for example, in the fuel cell disclosed in Patent Document 1, a cooling medium inlet communication hole and a cooling medium outlet communication hole are provided on both sides of the separator, and an air vent is provided above the cooling medium outlet communication hole. The communication hole is formed so that at least a part thereof is located above the uppermost part of the cooling medium flow path.

  Thereby, the air moving through the cooling medium flow path is smoothly and reliably discharged into the air vent communication hole, and it is possible to effectively prevent the air from remaining in the cooling medium flow path. Therefore, the effect of improving the cooling efficiency of the fuel cell with a simple configuration can be obtained.

Japanese Unexamined Patent Publication No. 2004-193110 (FIG. 1)

  By the way, in the fuel cell, the solid polymer electrolyte membrane is sandwiched between the cathode side electrode and the anode side electrode, and for example, the cathode side electrode is set to have a larger (or smaller) surface area than the anode side electrode. A step MEA may be employed.

  In this type of step MEA, on the electrode surface side of one separator, a reaction gas seal that circulates around the step MEA to prevent leakage of fuel gas and oxidant gas, and a solid polymer electrolyte surrounding the anode side electrode An electrode seal in close contact with the membrane is attached to form a so-called double seal. Further, a refrigerant seal corresponding to the reaction gas seal is attached to the refrigerant surface side of one separator so as to seal the cooling medium flow path.

  In this case, the reactive gas seal and the refrigerant seal are configured to receive the sealing pressure in the stacking direction by being provided at substantially the same position in the stacking direction. Accordingly, it is preferable that a backing convex portion is provided on the coolant surface of the separator in order to receive a sealing pressure in the electrode seal laminating direction.

  In the fuel cell employing this type of step MEA, the present invention can reliably prevent air from remaining in the coolant flow path with a simple configuration by using the convex portion for backing. An object of the present invention is to provide a fuel cell capable of having a good cooling function.

  The present invention includes an electrolyte / electrode structure in which a first electrode and a second electrode having a surface area smaller than that of the first electrode are arranged on both sides of the electrolyte, and the electrolyte / electrode structure is a first and a second. The first and second layers are sandwiched between metal separators, and are formed in the stacking direction so as to form a reaction gas inlet communication hole, a reaction gas outlet communication hole, a cooling medium inlet communication hole, and a cooling medium outlet communication hole. In the fuel cell, a cooling medium flow path communicating with the cooling medium inlet communication hole and the cooling medium outlet communication hole is formed between the metal separators.

  The first and second metal separators are provided with first and second reaction gas channels having bent portions or curved portions on the first and second electrode surfaces facing the first and second electrodes, respectively, and On the first and second coolant surfaces opposite to the second electrode surface, the back surfaces of the first and second reaction gas channels are overlapped to form the cooling medium channel.

And the 2nd metal separator which provides the electrode seal which surrounds the 2nd electrode has the refrigerant seal which seals a cooling medium on the 2nd refrigerant surface, and the convex part for backing of the electrode seal, and the refrigerant seal between the back-receiving convex portion and the air vent passage are provided, and one end of the air vent passage is in communication with the air vent passage which is formed above the coolant discharge passage, the The backing convex portion has a notch in a region located above the bent portion or the curved portion of the cooling medium flow path.

According to the present invention, a second metal separator provided with an electrode seal surrounding the second electrode has a refrigerant seal for sealing a cooling medium and a convex portion for backing the electrode seal on the second refrigerant surface. In addition, an air vent passage is provided between the refrigerant seal and the backing convex portion , and one end of the air vent passage is an air vent communicating hole formed above the cooling medium outlet communicating hole . and communicating the other end of the air vent passage communicates with the coolant supply passage.

Further, on the upper and lower side Mukonaka central portion of the horizontal ends of the first and second metal separators, while the coolant supply passages are provided, and below the other horizontal end portion of said first and second metal separators square the Mukonaka central unit, together with the coolant discharge passage is provided, wherein the upper portion of the other horizontal end portions of the first and second metal separators, wherein the cooling medium flow at least partially air vent passage It is preferable to be formed above the uppermost portion of the path so as to penetrate in the stacking direction.

  Furthermore, it is preferable that a throttle portion is provided in the vicinity of the other end of the air vent passage in the vicinity of the cooling medium inlet communication hole. Bubbles in the cooling medium introduced from the cooling medium inlet communication hole are discharged to the air vent passage through the throttle portion, while the cooling medium is prevented from moving to the air vent passage under the action of the throttle portion. Is done. For this reason, a cooling medium is reliably supplied to a cooling medium flow path, and can cool an electrode surface efficiently.

  In the present invention, an air vent passage is provided between the refrigerant seal and the backing convex portion, and the backing convex portion is located in a region located above the bent portion or the curved portion of the cooling medium flow path. A notch is provided. At this time, the bent portion or the curved portion of the cooling medium flow path is formed by overlapping the back surfaces of the first and second reaction gas flow paths, and in fact extends in the vertical direction with the horizontal groove extending in the horizontal direction. The cross flow path which intersects with the vertical groove is configured.

  For this reason, the cooling medium supplied to the cooling medium flow path is likely to be agitated in the cross flow path to generate air bubbles, but the air bubbles pass from the notch provided above the cross flow path to the air vent passage. It is discharged smoothly and quickly. As a result, bubbles do not remain in the cooling medium flow path, and it is possible to prevent a decrease in cooling performance with a simple configuration using the backing convex portion, and to have a good cooling function. It becomes possible.

  In the present invention, one end of the air vent passage communicates with the air vent communication hole, and the other end of the air vent passage communicates with the cooling medium inlet communication hole. Therefore, bubbles contained in the cooling medium supplied from the cooling medium inlet communication hole are prevented from being reliably discharged into the air vent path and introduced into the cooling medium flow path. Accordingly, the cooling medium from which bubbles are removed can be satisfactorily supplied to the cooling medium flow path, and the heat exchange efficiency can be improved.

  FIG. 1 is an exploded perspective view of a main part of a fuel cell 10 according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of a fuel cell stack 11 in which the fuel cells 10 are stacked.

  The fuel cell 10 is configured by alternately laminating electrolyte membrane / electrode structures (electrolyte / electrode structures) 12 and separators 13, and the separators 13 are first and second metal plates that are laminated to each other. (Metal separator) 14 and 16 are provided.

  As shown in FIG. 1, an oxidant gas (reactive gas), for example, an oxygen-containing gas is supplied to one end edge of the fuel cell 10 in the arrow B direction so as to communicate with each other in the direction of arrow A, which is the stacking direction An oxidant gas inlet communication hole 20a for supplying a coolant, a cooling medium inlet communication hole 22a for supplying a cooling medium, and a fuel gas outlet reaction hole 24b for discharging a fuel gas (reactive gas), for example, a hydrogen-containing gas, Arranged in the direction of arrow C (vertical direction).

  The other end edge of the fuel cell 10 in the direction of arrow B communicates with each other in the direction of arrow A, the fuel gas inlet communication hole 24a for supplying fuel gas, and the cooling medium outlet communication hole for discharging the cooling medium. 22b and an oxidant gas outlet communication hole 20b for discharging the oxidant gas are arranged in the direction of arrow C.

  As shown in FIGS. 1 and 2, the electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane (electrolyte) 26 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane. 26, an anode side electrode (second electrode) 28 and a cathode side electrode (first electrode) 30 are provided. The anode side electrode 28 is set to have a smaller surface area than the cathode side electrode 30, and the cathode side electrode 30 is provided so as to cover the entire surface of the solid polymer electrolyte membrane 26 (so-called step MEA).

  The anode side electrode 28 and the cathode side electrode 30 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface. And an electrode catalyst layer (not shown). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 26. The electrolyte membrane / electrode structure 12 as a whole is formed in a substantially quadrangular shape, and the four corner portions are provided with four projecting shape portions projecting outward corresponding to the respective diagonal positions.

  As shown in FIGS. 1 and 3, an oxidant gas flow path 32 is provided on the surface (first electrode surface) 14 a of the first metal plate 14 facing the electrolyte membrane / electrode structure 12, and this oxidant is provided. The gas flow path 32 communicates with the oxidant gas inlet communication hole 20a and the oxidant gas outlet communication hole 20b. The oxidant gas flow path 32 has a substantially right triangle inlet buffer 34 provided in the vicinity of the oxidant gas inlet communication hole 20a and a substantially right triangle in the shape of the oxidant gas outlet communication hole 20b. And an outlet buffer unit 36.

  The inlet buffer unit 34 and the outlet buffer unit 36 communicate with each other through a plurality of oxidant gas flow channel grooves 32 a constituting the oxidant gas flow channel 32. The oxidant gas flow path 32 constitutes a serpentine flow path having an even-numbered, for example, twice-folded portion in the surface 14a of the first metal plate 14.

  A planar seal 40a is provided on the surface 14a of the first metal plate 14 to seal the oxidant gas around the oxidant gas inlet communication hole 20a, the oxidant gas outlet communication hole 20b, and the oxidant gas flow path 32. It is done.

  Between the surfaces 14b, 16b of the first metal plate 14 and the second metal plate 16 facing each other, a cooling medium flow path 42 described later is integrally formed. As shown in FIG. 4, a part of the cooling medium flow path 42 is formed on the surface (first refrigerant surface) 14b of the first metal plate 14 as a back side shape of the oxidant gas flow path 32 formed on the surface 14a side. The channel portion 42a is formed in a serpentine shape.

  The surface 14b has an inlet buffer portion 44 that communicates with the cooling medium inlet communication hole 22a via an inlet communication channel 43, and an outlet buffer unit 50 that communicates with the cooling medium outlet communication hole 22b via an outlet communication channel 48. Is provided.

  A planar seal 40b is provided on the surface 14b of the first metal plate 14 to circulate the cooling medium inlet communication hole 22a, the cooling medium outlet communication hole 22b, and the cooling medium flow path 42 to seal the cooling medium. The planar seals 40a and 40b constitute a first seal member 40 that is integrally provided so as to cover the outer peripheral end of the first metal plate 14 (see FIG. 2).

  As shown in FIG. 5, a fuel gas flow path 52 is provided on the surface (second electrode surface) 16 a of the second metal plate 16 facing the electrolyte membrane / electrode structure 12. The fuel gas flow path 52 includes a substantially right triangular inlet buffer portion 54 provided close to the fuel gas inlet communication hole 24a and a substantially right triangular outlet buffer portion provided close to the fuel gas outlet communication hole 24b. 56.

  The inlet buffer unit 54 and the outlet buffer unit 56 are configured to be substantially symmetrical with each other, and in the vicinity of the inlet buffer unit 54 and the outlet buffer unit 56, a plurality of fuel gas inlet holes 58a and fuel gas outlet holes are provided. A portion 58b is formed.

  The inlet buffer portion 54 and the outlet buffer portion 56 communicate with each other via a plurality of fuel gas flow channel grooves 52 a that constitute the fuel gas flow channel 52. The fuel gas flow path 52 constitutes a serpentine flow path having an even-numbered, for example, twice-folded portion in the surface 16b of the second metal plate 16.

  As shown in FIG. 6, the surface (second refrigerant surface) 16b of the second metal plate 16 is a part of the cooling medium flow path 42 as the back side shape of the fuel gas flow path 52 formed on the surface 16a. The flow path part 42b is formed in a serpentine shape. The surface 16b communicates with the cooling medium inlet communication hole 22a via the inlet communication channel 60 through a substantially right triangular inlet buffer 62, and communicates with the cooling medium outlet communication hole 22b via the outlet communication channel 64. A substantially right triangle-shaped outlet buffer section 66 is provided.

  As shown in FIG. 7, when the first metal plate 14 and the second metal plate 16 are laminated, the cooling medium flow path 42 has a back side of the oxidant gas flow path 32 and a back side of the fuel gas flow path 52. Overlapping and forming integrally. The oxidant gas flow channel 32 and the fuel gas flow channel 52 constitute a serpentine flow channel that is folded back and forth once in the direction of arrow B, and a horizontal groove that extends in one horizontal direction (arrow B direction) by overlapping each other. Cross passages 68 a to 68 d intersecting with the longitudinal grooves extending in the longitudinal direction (arrow C direction) are formed corresponding to the four corners of the cooling medium passage 42.

  As shown in FIG. 5, the second seal member 70 is integrally formed so as to cover the outer peripheral end of the second metal plate 16. The second seal member 70 includes an outer linear seal (reactive gas seal) 72 provided on the surface 16a, and an inner linear seal (electrode seal) 74 spaced inward from the outer linear seal 72 by a predetermined distance. Have

  The outer linear seal 72 circulates around the outer periphery of the electrolyte membrane / electrode structure 12 and is superposed on the planar seal 40a provided on the first metal plate 14, as shown in FIG. The inner linear seal 74 circulates around the anode side electrode 28 and contacts the outer peripheral edge of the solid polymer electrolyte membrane 26 to close the fuel gas flow path 52 (see FIG. 2).

  As shown in FIG. 6, the second seal member 70 includes a linear seal 76 provided on the surface 16 b, and a backing convex portion 78 provided at a predetermined distance inside the linear seal 76. Have The linear seal 76 constitutes a refrigerant seal that covers the cooling medium flow path 42 and seals the cooling medium. On the other hand, the convex portion 78 is provided at a position overlapping the inner linear seal 74 provided on the surface 16 a in the stacking direction, and functions as a backing that receives the sealing pressure in the stacking direction of the inner linear seal 74.

  An air vent passage 80 is formed between the linear seal 76 and the convex portion 78 on the upper side of the surface 16b. An air vent communication hole 81 is formed on the upper end of the second metal plate 16 in the direction of arrow B, specifically, above the fuel gas inlet communication hole 24a. At least a part of the air vent communication hole 81 is disposed above the uppermost part of the cooling medium flow path 42. One end of the air vent passage 80 communicates with the air vent communication hole 81, and the other end of the air vent passage 80 communicates with the cooling medium inlet communication hole 22a.

  The convex portion 78 constituting the air vent passage 80 is provided with a notch portion 82 in a region located at least above the cross passages 68 a and 68 b of the cooling medium passage 42. Note that the cutout portion 82 may be provided in a region located above the cross flow paths 68c and 68d as necessary. A constriction portion 86 is provided in the connection path 84 that connects the air vent passage 80 and the cooling medium inlet communication hole 22a in the vicinity of the cooling medium inlet communication hole 22a.

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

  As shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 20a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 24a. Further, a cooling medium such as pure water or ethylene glycol is supplied to the cooling medium inlet communication hole 22a.

  The oxidant gas is introduced into the oxidant gas channel 32 of the first metal plate 14 from the oxidant gas inlet communication hole 20a. In the oxidant gas flow path 32, the oxidant gas is once introduced into the inlet buffer section 34 and then dispersed in the plurality of oxidant gas flow path grooves 32a. Therefore, the oxidant gas moves along the cathode side electrode 30 of the electrolyte membrane / electrode structure 12 while meandering through the respective oxidant gas flow channel grooves 38.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 52 from the fuel gas inlet communication hole 24 a through the fuel gas inlet hole 58 a of the second metal plate 16. In the fuel gas channel 52, as shown in FIG. 5, the fuel gas is once introduced into the inlet buffer portion 54 and then dispersed into the plurality of fuel gas channel grooves 52a. Further, the fuel gas meanders through each fuel gas flow channel groove 52 a and moves along the anode side electrode 28 of the electrolyte membrane / electrode structure 12.

  Therefore, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode side electrode 30 and the fuel gas supplied to the anode side electrode 28 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power. Is done.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 30 is discharged from the outlet buffer 36 to the oxidant gas outlet communication hole 20b (see FIG. 1). Similarly, the fuel gas supplied to and consumed by the anode side electrode 28 is discharged from the outlet buffer portion 56 to the fuel gas outlet communication hole 24b through the fuel gas outlet hole portion 58b (see FIG. 5).

  On the other hand, the cooling medium supplied to the cooling medium inlet communication hole 22 a is introduced into a cooling medium flow path 42 formed between the first and second metal plates 14 and 16. In the cooling medium flow path 42, as shown in FIG. 7, the cooling medium is temporarily supplied to the inlet buffer sections 44 and 62 via the inlet communication flow paths 43 and 60 extending in the direction of arrow C from the cooling medium inlet communication hole 22a. be introduced.

  The cooling medium introduced into the inlet buffer sections 44 and 62 is dispersed in the plurality of flow path sections 42a and 42b and moves in the horizontal direction (arrow B direction) and the vertical direction (arrow C direction). Therefore, after the cooling medium is supplied over the entire electrode surface of the electrolyte membrane / electrode structure 12, the cooling medium is once introduced into the outlet buffer units 50 and 66, and further through the outlet communication channels 48 and 64. It is discharged to 22b.

  In this case, in this embodiment, the electrolyte membrane / electrode structure 12 constitutes a so-called step MEA. Therefore, on the surface 16b which is the second refrigerant surface of the second metal plate 16, as shown in FIG. 6, a linear seal 76 which is a refrigerant seal and an inner line which is an electrode seal provided on the surface 16a side. And a convex portion 78 for backing to receive the sealing pressure of the cylindrical seal 74.

  Further, on the upper side of the second metal plate 16, an air vent passage 80 is formed between the linear seal 76 and the convex portion 78, and a cross flow of the cooling medium flow path 42 is formed in the convex portion 78. A notch 82 is provided in a region located above the paths 68a and 68b (see FIG. 7).

  Therefore, in the cooling medium flow path 42, when the cooling medium is introduced from the inlet buffer sections 44 and 62 to the flow path sections 42a and 42b, the cross flow paths 68a and 68b in which the transverse grooves and the vertical grooves intersect with each other in practice. The cooling medium is stirred and bubbles are easily generated. The bubbles move above the cooling medium flow path 42 and are smoothly and quickly discharged from the notch 82 to the air vent passage 80. Next, the bubbles discharged to the air vent passage 80 move in the direction of arrow B along the air vent passage 80 and are discharged to the outside from the air vent communication hole 81.

  Thereby, in this embodiment, air bubbles do not remain in the cooling medium flow path 42 with a simple configuration, it is possible to prevent the cooling performance from being lowered, and it is possible to have a good cooling medium function. The effect is obtained.

  Note that the notch 82 may be provided in a region located above the cross flow paths 86c and 86d on the cooling medium outlet communication hole 22b side. For this reason, bubbles that are likely to be generated in the cross flow paths 68c and 68d are discharged smoothly and quickly into the air vent passage 80.

  Further, in the present embodiment, one end of the air vent passage 80 communicates with the cooling medium inlet communication hole 22 a via the connection path 84. Therefore, the bubbles contained in the cooling medium supplied from the cooling medium inlet communication hole 22a are discharged from the connection path 84 to the air vent path 80 and can be prevented from being introduced into the cooling medium flow path 42. . As a result, the cooling medium flow path 42 can satisfactorily supply the cooling medium from which bubbles are removed, and the heat exchange efficiency can be improved.

  Furthermore, a throttle part 86 is provided in the connection path 84 in the vicinity of the cooling medium inlet communication hole 22a. Therefore, bubbles in the cooling medium introduced from the cooling medium inlet communication hole 22 a are discharged to the air vent passage 80 through the throttle portion 86, while the cooling medium is released from the air under the action of the throttle portion 86. Movement to the passage 80 is prevented. Accordingly, it is possible to prevent the cooling medium from being discharged through the air vent passage 80 without being used for cooling the electrode surface, and to reliably supply the cooling medium to the cooling medium flow path 42 to It becomes possible to cool efficiently.

  Note that the cooling medium outlet communication hole 22b and the air vent passage 80 may be configured to communicate with each other via the connection path 84a (see FIG. 6). As a result, bubbles generated in the vicinity of the cooling medium outlet communication hole 22b are quickly and smoothly discharged to the air vent passage 80 through the connection path 84a, and a decrease in cooling efficiency due to the bubbles can be prevented.

  Further, in the present embodiment, the cooling medium flow path 42 is provided integrally with the oxidant gas flow path 32 of the serpentine flow path and the back side of the fuel gas flow path 52 that are reciprocated halfway in the direction of arrow B, respectively. However, it is not limited to this. For example, the oxidant gas channel 32 and the fuel gas channel 52 may be substantially U-shaped channels having bent portions or curved portions. In other words, it suffices if a bent portion or a curved portion is provided in the reaction gas channel. This is because the air vent passage 80 has the same effect as that of the present embodiment by providing the notch 82 in a region located above the bent or curved portion.

It is a principal part disassembled perspective view of the fuel cell which concerns on embodiment of this invention. FIG. 3 is a partial cross-sectional explanatory view of a fuel cell stack in which the fuel cells are stacked. It is explanatory drawing of one surface of a 1st metal plate. It is explanatory drawing of the other surface of the said 1st metal plate. It is explanatory drawing of one surface of a 2nd metal plate. It is explanatory drawing of the other surface of the said 2nd metal plate. It is a perspective explanatory view of a cooling medium channel formed in a metal separator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Electrolyte membrane electrode assembly 13 ... Metal separator 14, 16 ... Metal plates 14a, 14b, 16a, 16b ... Surface 20a ... Oxidant gas inlet communication hole 20b ... Oxidant gas outlet communication hole 22a ... Cooling Medium inlet communication hole 22b ... Cooling medium outlet communication hole 24a ... Fuel gas inlet communication hole 24b ... Fuel gas outlet communication hole 26 ... Solid polymer electrolyte membrane 28 ... Anode side electrode 30 ... Cathode side electrode 32 ... Oxidant gas flow path 34 , 44, 54, 62 ... Inlet buffer portion 36, 50, 56, 66 ... Outlet buffer portion 42 ... Cooling medium passage 52 ... Fuel gas passage 70 ... Seal member 72 ... Outer linear seal 74 ... Inner linear seal 76 ... Linear seal 78 ... Convex part 80 ... Air vent passage 81 ... Air vent communication hole 82 ... Notch 84 ... Connection path 86 ... Throttle part

Claims (4)

An electrolyte / electrode structure having a first electrode and a second electrode having a surface area smaller than that of the first electrode on both sides of the electrolyte is provided, and the electrolyte / electrode structure is sandwiched between first and second metal separators In addition, a reaction gas inlet communication hole, a reaction gas outlet communication hole, a cooling medium inlet communication hole, and a cooling medium outlet communication hole are formed penetrating in the stacking direction between the first and second metal separators stacked on each other. Is a fuel cell in which a cooling medium flow path communicating with the cooling medium inlet communication hole and the cooling medium outlet communication hole is formed,
The first and second metal separators are provided with first and second reactive gas flow paths having bent portions or curved portions on first and second electrode surfaces facing the first and second electrodes, and On the first and second refrigerant surfaces opposite to the first and second electrode surfaces, the cooling medium flow path is formed by overlapping the back surfaces of the first and second reaction gas flow paths,
The second metal separator that provides an electrode seal that surrounds the second electrode has a refrigerant seal that seals a cooling medium and a convex portion for backing the electrode seal on the second refrigerant surface,
An air vent passage is provided between the refrigerant seal and the backing convex portion , and one end of the air vent passage communicates with an air vent communication hole formed above the cooling medium outlet communication hole. And
The fuel cell according to claim 1, wherein the backing convex portion is provided with a notch in a region located above the bent portion or the curved portion of the cooling medium flow path. An electrolyte / electrode structure having a first electrode and a second electrode having a surface area smaller than that of the first electrode on both sides of the electrolyte is provided, and the electrolyte / electrode structure is sandwiched between first and second metal separators In addition, a reaction gas inlet communication hole, a reaction gas outlet communication hole, a cooling medium inlet communication hole, and a cooling medium outlet communication hole are formed penetrating in the stacking direction between the first and second metal separators stacked on each other. Is a fuel cell in which a cooling medium flow path communicating with the cooling medium inlet communication hole and the cooling medium outlet communication hole is formed,
The first and second metal separators are provided with first and second reactive gas flow paths having bent portions or curved portions on first and second electrode surfaces facing the first and second electrodes, and On the first and second refrigerant surfaces opposite to the first and second electrode surfaces, the cooling medium flow path is formed by overlapping the back surfaces of the first and second reaction gas flow paths,
The second metal separator that provides an electrode seal that surrounds the second electrode has a refrigerant seal that seals a cooling medium and a convex portion for backing the electrode seal on the second refrigerant surface,
Between the coolant seal and the back receiving convex shape portion, the air vent passage are provided, and one end of the air vent passage communicating the air vent passage which is formed above the coolant discharge passage and through,
The other end of the air vent passage communicates with the cooling medium inlet communication hole. A fuel cell according to claim 1 or 2, wherein, while the the upper and lower side Mukonaka central portion of the horizontal ends of the first and second metal separators, the coolant supply passages are provided,
Wherein the upper and lower side Mukonaka central portion of the other horizontal end portions of the first and second metal separators, together with the coolant discharge passage is provided,
At the upper part of the other horizontal end of the first and second metal separators, the air vent communication hole is formed at least partially above the uppermost part of the cooling medium flow path and penetrates in the stacking direction. A fuel cell.   4. The fuel cell according to claim 2, wherein a throttle portion is provided in the vicinity of the other end of the air vent passage in the vicinity of the cooling medium inlet communication hole.

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