JP5583824B2 - Fuel cell - Google Patents

Description

  In the present invention, an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte and a metal separator are laminated, and a cooling medium is circulated along the electrode surface direction between the metal separators adjacent to each other. The present invention relates to a fuel cell in which a cooling medium flow path is formed.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is provided by a pair of separators. The unit cell is sandwiched. This type of fuel cell is normally used as an in-vehicle fuel cell stack by stacking a predetermined number of unit cells.

  In the above fuel cell, a fuel gas flow channel for flowing fuel gas is provided in the plane of one separator so as to face the anode side electrode, and the cathode side electrode is opposed in the plane of the other separator. An oxidant gas flow path for flowing an oxidant gas is provided. Furthermore, a cooling medium flow path for flowing a cooling medium in the electrode range is formed between the separators constituting each fuel cell and adjacent to each other.

  As the separator, a metal separator may be employed in place of the carbon separator because it is particularly easy to reduce the thickness. At that time, a wave-shaped channel groove is formed by press-forming a thin metal plate. The channel groove is selectively used as a fuel gas channel or an oxidant gas channel, thereby forming an anode-side separator or a cathode-side separator.

  On the other hand, between the anode side separator and the cathode side separator adjacent to each other, the back surface shape of the fuel gas channel and the back surface shape of the oxidant gas channel are overlapped to form a cooling medium channel.

  As this type of fuel cell, for example, a fuel cell stack disclosed in Patent Document 1 is known. As shown in FIG. 9, the fuel cell stack includes a unit cell 1, and the unit cell 1 has separators 3 and 4 disposed on both surfaces of a membrane electrode structure 2.

  A fuel gas supply port 5a and an oxidant gas supply port 6a are provided through the upper end portion in the longitudinal direction of the unit cell 1 in the stacking direction, and a fuel gas discharge port is provided at the lower end portion in the longitudinal direction of the unit cell 1. 5b and an oxidizing gas discharge port 6b are formed penetrating in the stacking direction. At both ends in the short direction of the unit cell 1, four cooling water supply ports 7a and cooling water discharge ports 7b are arranged in the vertical direction.

  A surface of the separator 3 facing the membrane electrode structure 2 is formed with a plurality of wavy fuel gas passages 8a that communicate with the fuel gas supply port 5a and the fuel gas discharge port 5b and extend in the longitudinal direction. Yes. On the surface of the separator 4 facing the membrane electrode structure 2, there are a plurality of undulating oxidant gas flow paths 9 a that communicate with the oxidant gas supply port 6 a and the oxidant gas discharge port 6 b and extend in the longitudinal direction. Is formed.

  By laminating the unit cells 1 to each other, a cooling water flow path is formed between the separator 3 constituting one unit cell 1 and the separator 4 constituting the other unit cell 1. This cooling water flow path is formed by overlapping the groove shape 8b on the back surface side of the fuel gas flow path 8a and the groove shape 9b on the back surface side of the oxidant gas flow path 9a so that the cooling medium flows in the short direction (horizontal direction). Allowing the flow, the cooling water supply port 7a and the cooling water discharge port 7b communicate with each other.

JP 2007-141552 A

  By the way, in the fuel cell, the flow direction of the cooling water may be set in substantially the same direction as the flow direction of the fuel gas and the flow direction of the oxidant gas. For example, in the unit cell 1, the cooling water discharge port 7 b at the upper end in the longitudinal direction is used as a cooling water supply port 7 a, and a pair of left and right cooling water supply ports 7 a and 7 a are provided on the upper side of the unit cell 1. A configuration in which a pair of left and right cooling water discharge ports 7b and 7b are provided at the lower end in the longitudinal direction is considered. This is because each of the groove shapes 8b and 9b meanders in a wave shape, so that a flow path capable of circulating cooling water along the horizontal direction and the vertical direction is formed between them.

  Thereby, the cooling water is introduced from the pair of left and right cooling water supply ports 7a, 7a to face each other inward in the lateral direction. This cooling water moves along the vertical downward direction, and further moves outward in the lateral direction, thereby forming a so-called H flow discharged from the pair of cooling water discharge ports 7b and 7b. Can do.

  However, in the cooling water flow path, it is difficult for the cooling water to be supplied to the central portion in the width direction (horizontal direction), and a shortage of the cooling water supply amount easily occurs. As a result, there is a problem in that a high-temperature portion is generated in the cooling water flow path, and the temperature distribution in the power generation surface varies.

  The present invention solves this type of problem, and provides a fuel cell capable of making the temperature distribution uniform throughout the entire power generation surface with a simple configuration and improving the power generation performance. With the goal.

The present invention, a pair of electrodes are provided on both sides of the electrolyte and the electrolyte electrode assembly and the rectangular shape of the metallic plates are stacked, a fuel gas and oxidizer gas in the stacking direction to the longitudinal direction end portion of the metal separator while the first fuel gas communication hole and the first oxidant gas passage circulating is formed, circulated prior Symbol fuel gas and the oxidant gas in the stacking direction to the longitudinal direction other end portion of the metal separator is the second fuel gas communication hole and the second oxidant gas passage causes the formation, the more short direction both end portions of the metal separator, the first fuel gas communication hole and the first oxide a pair of coolant supply passage of the cooling medium prior to use in proximity to agent gas passage circulating in the stacking direction, the second fuel gas communication hole and the second oxidant gas communication hole A pair of the cooling medium after use in the vicinity of the And 却媒 body discharge passage is a fuel cell that is formed.

The fuel cell, on the surface of the metallic plates toward one electrode, in the first fuel gas communication hole and the second fuel gas communication hole, a fuel gas supply side through the inlet mouth buffer, In addition, the fuel gas discharge side communicates with each other via the outlet buffer portion, and a wavy fuel gas flow path extending in the longitudinal direction is provided, and the surface of the metal separator facing the other electrode has a first oxidation agent in the gas communication hole and the second oxidant gas communication hole, an oxidant gas supply side through the inlet mouth buffer, and the oxidizing gas discharge side via the outlet buffer, each communicating A wave-shaped oxidant gas flow path extending in the longitudinal direction is provided.

  Then, between the metal separators adjacent to each other, a cooling medium is provided by a wave groove shape portion formed on the back surface side of the fuel gas flow path and a wave groove shape portion formed on the back surface side of the oxidant gas flow path. A cooling medium flow path to be circulated is formed, and a plurality of inlet connection passages for connecting the cooling medium supply communication hole and the cooling medium flow path are provided.

  Here, the plurality of inlet connection passages supply the flow rate of the cooling medium supplied toward the other side of the inlet buffer shape portion that is the back surface shape of the inlet buffer portion of the cooling medium flow path. A cooling medium increasing portion that increases the flow rate of the cooling medium is configured.

  The cooling medium increasing portion is configured by setting the passage width of the inlet connection passage on the inlet buffer shape portion side to be larger than the passage width of the inlet connection passage on the side away from the inlet buffer shape portion. Is preferred.

  Further, the cooling medium increasing portion is configured by inclining the inlet connection passage on the inlet buffer shape portion side toward the inlet buffer shape portion side from a direction parallel to the inlet connection passage on the side away from the inlet buffer shape portion. It is preferred that

  Furthermore, the cooling medium increasing part is preferably provided between the inlet buffer shape part of the cooling medium flow path and the first wave-like top part.

  According to the present invention, the flow rate of the cooling medium supplied toward the inlet buffer shape portion side of the cooling medium flow path is increased from the flow rate of the cooling medium supplied toward the other part. For this reason, the cooling medium flows through the inlet buffer shape portion and is reliably supplied to the central portion in the width direction of the cooling medium flow path, and it is possible to prevent the cooling water supply amount from being insufficient.

  Thereby, with a simple configuration, the temperature distribution and the humidity distribution can be made uniform over the entire power generation plane, and the power generation performance can be easily improved.

It is a principal part disassembled perspective explanatory drawing of the fuel cell which concerns on the 1st Embodiment of this invention. FIG. 2 is a sectional view of the fuel cell taken along line II-II in FIG. 1. It is explanatory drawing of one front of the 2nd metal separator which comprises the said fuel cell. It is explanatory drawing of the other front of the said 2nd metal separator. It is a principal part perspective view of the cooling-medium flow path which comprises the said fuel cell. It is principal part expansion explanatory drawing of the said 2nd metal separator. It is principal part expansion explanatory drawing of the 2nd metal separator which comprises the fuel cell which concerns on the 2nd Embodiment of this invention. It is principal part expansion explanatory drawing of the 2nd metal separator which comprises the fuel cell which concerns on the 3rd Embodiment of this invention. FIG. 3 is an exploded perspective view of a main part of a fuel cell stack disclosed in Patent Document 1.

  As shown in FIGS. 1 and 2, a plurality of fuel cells 10 according to the first embodiment of the present invention are stacked in the direction of arrow A to constitute a fuel cell stack 11. The fuel cell 10 includes an electrolyte membrane / electrode structure 12, and a first metal separator 14 and a second metal separator 16 that sandwich the electrolyte membrane / electrode structure 12.

  The first metal separator 14 and the second metal separator 16 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate whose surface has been subjected to anticorrosion treatment. The first metal separator 14 and the second metal separator 16 have a rectangular planar shape, and are formed into a concavo-convex shape by pressing a metal thin plate into a wave shape.

  As shown in FIG. 1, the first metal separator 14 and the second metal separator 16 have a vertically long shape, the long side faces in the direction of gravity (arrow C direction), and the short side in the horizontal direction (arrow B direction). It is configured to face (horizontal stacking). In addition, you may comprise so that a long side may face a horizontal direction and a short side may go to a gravitational direction, and you may comprise so that a separator surface may go to a horizontal direction (vertical lamination | stacking).

  An oxidant gas supply communication hole 18a for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the direction of the arrow A in the vicinity of the upper corners of the long side direction (arrow C direction) of the fuel cell 10. And a fuel gas supply passage 20a for supplying a fuel gas, for example, a hydrogen-containing gas.

  In the vicinity of the lower corners of the long side direction of the fuel cell 10, the fuel gas discharge communication hole 20 b for discharging the fuel gas and the oxidant gas for discharging the oxidant gas are communicated with each other in the direction of arrow A. A discharge communication hole 18b is provided.

  Two cooling medium supply communication holes 22 a for communicating with each other in the direction of arrow A and for supplying a cooling medium are provided above both edge portions in the short side direction (arrow B direction) of the fuel cell 10. Two cooling medium discharge communication holes 22 b for discharging the cooling medium are provided below both edge portions in the short side direction of the fuel cell 10.

  The electrolyte membrane / electrode structure 12 includes, for example, a solid polymer electrolyte membrane 24 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode side electrode 26 and an anode side electrode 28 that sandwich the solid polymer electrolyte membrane 24. With.

  The cathode side electrode 26 and the anode side electrode 28 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) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 24.

  An oxidant gas flow path 30 that connects the oxidant gas supply communication hole 18 a and the oxidant gas discharge communication hole 18 b is formed on the surface 14 a of the first metal separator 14 facing the electrolyte membrane / electrode structure 12. The oxidant gas flow path 30 is formed between a plurality of wavy convex portions 30a extending in the direction of arrow C, and a plurality of embosses are provided near the inlet and the outlet of the oxidant gas flow path 30, respectively. An inlet buffer portion 32a and an outlet buffer portion 32b are provided.

  As shown in FIG. 3, a fuel gas flow path 34 that connects the fuel gas supply communication hole 20 a and the fuel gas discharge communication hole 20 b is formed on the surface 16 a of the second metal separator 16 facing the electrolyte membrane / electrode structure 12. It is formed. The fuel gas channel 34 is formed between a plurality of wavy convex portions 34a extending in the direction of arrow C, and an inlet having a plurality of embosses in the vicinity of the inlet and the outlet of the fuel gas channel 34, respectively. A buffer unit 36a and an outlet buffer unit 36b are provided.

  Between the surface 16b of the second metal separator 16 and the surface 14b of the first metal separator 14, there is a cooling medium flow path 38 communicating with the cooling medium supply communication holes 22a, 22a and the cooling medium discharge communication holes 22b, 22b. Formed (see FIGS. 1 and 4). The cooling medium flow path 38 circulates the cooling medium over the electrode range of the electrolyte membrane / electrode structure 12.

  As shown in FIGS. 1 and 5, the cooling medium flow path 38 forms a fuel gas flow path 34 and a wave groove shape portion 30 b which is the back surface shape of the wavy convex portion 30 a constituting the oxidant gas flow path 30. It is formed by overlapping the wave groove shape portion 34b which is the back surface shape of the wave shape convex portion 34a. In the vicinity of the inlet and the outlet of the cooling medium flow path 38, an inlet buffer shape portion 40a and an outlet buffer portion 40b, which are the back surface shapes of the inlet buffer portion 36a and the outlet buffer portion 36b, are provided, respectively (see FIG. 4).

  A first seal member 42 is integrally formed on the surfaces 14 a and 14 b of the first metal separator 14 around the outer edge of the first metal separator 14. A second seal member 44 is integrally formed on the surfaces 16 a and 16 b of the second metal separator 16 around the outer peripheral edge of the second metal separator 16. As the first seal member 42 and the second seal member 44, for example, EPDM, NBR, fluororubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber or the like, cushion material Or a packing material is used.

  As shown in FIG. 1, the surface 14 a of the first metal separator 14 has a plurality of connecting passages 46 a that cut the first seal member 42 to communicate the oxidizing gas supply communication hole 18 a and the oxidizing gas channel 30. Is formed. A plurality of connecting passages 46 b are formed in the surface 14 a so as to communicate the oxidant gas discharge communication hole 18 b and the oxidant gas flow path 30 by cutting out the first seal member 42.

  As shown in FIG. 3, a plurality of connecting passages 50 a are formed in the surface 16 a of the second metal separator 16 so as to communicate the fuel gas supply communication hole 20 a and the fuel gas passage 34 by cutting out the second seal member 44. Is done. A plurality of connecting passages 50 b are formed in the surface 16 a so as to connect the fuel gas discharge communication hole 20 b and the fuel gas passage 34 by cutting out the second seal member 44.

  As shown in FIG. 4, the surface 16 b of the second metal separator 16 has a plurality of inlets that cut out the second seal member 44 to communicate the pair of cooling medium supply communication holes 22 a, 22 a and the cooling medium flow path 38. Connection passages 52a1 and 52a2 are formed. The plurality of inlet connection passages 52a1 increase the flow rate of the cooling medium supplied toward the inlet buffer shape portion 40a side of the cooling medium flow path 38 more than the flow rate of the cooling medium supplied toward other portions. A cooling medium increasing portion is configured.

  Specifically, as shown in FIGS. 4 and 6, the cooling medium increasing unit sets the passage width H1 of the plurality of inlet connection passages 52a1 larger than the passage width H2 of the plurality of inlet connection passages 52a2. Configured (H1> H2). The plurality of inlet connection passages 52a1 are provided between the inlet buffer shape portion 40a of the cooling medium flow path 38 and the first wave-like top portion P1 of the wave groove shape portion 34b (or the wave groove shape portion 30b).

  A plurality of outlet connection passages 52b are formed in the surface 16b by notching the second seal member 44 and communicating the pair of cooling medium discharge communication holes 22b, 22b and the cooling medium flow path 38 (FIGS. 1 and 4).

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

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 18a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply communication hole 20a. Supplied. Further, a coolant such as pure water, ethylene glycol, or oil is supplied to the pair of coolant supply passages 22a.

  For this reason, the oxidant gas is introduced into the oxidant gas flow path 30 of the first metal separator 14 from the oxidant gas supply communication hole 18a. The oxidant gas moves in the direction of arrow C (gravity direction) along the oxidant gas flow path 30 and is supplied to the cathode side electrode 26 of the electrolyte membrane / electrode structure 12.

  On the other hand, the fuel gas is supplied to the fuel gas flow path 34 of the second metal separator 16 from the fuel gas supply communication hole 20a. As shown in FIG. 3, the fuel gas moves in the gravitational direction (arrow C direction) along the fuel gas flow path 34 and is supplied to the anode side electrode 28 of the electrolyte membrane / electrode structure 12 (see FIG. 1 and FIG. 3). (See FIG. 2).

  Therefore, in the electrolyte membrane / electrode structure 12, the oxidant gas supplied to the cathode side electrode 26 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 supplied to and consumed by the cathode side electrode 26 of the electrolyte membrane / electrode structure 12 is discharged in the direction of arrow A along the oxidant gas discharge communication hole 18b. On the other hand, the fuel gas supplied to and consumed by the anode side electrode 28 of the electrolyte membrane / electrode structure 12 is discharged in the direction of arrow A along the fuel gas discharge communication hole 20b.

  Further, the cooling medium supplied to the pair of cooling medium supply communication holes 22a is introduced into the cooling medium flow path 38 between the first metal separator 14 and the second metal separator 16, as shown in FIG. As shown in FIG. 4, the cooling medium once flows in the direction of arrow B (horizontal direction) and then moves in the direction of arrow C (gravity direction) to cool the electrolyte membrane / electrode structure 12. The cooling medium moves outward in the direction of arrow B, and is then discharged to the pair of cooling medium discharge communication holes 22b.

  In this case, in the first embodiment, as shown in FIG. 6, the second metal separator 16 has a plurality of inlet connection passages 52 a 1 and 52 a 2 that connect the cooling medium supply communication hole 22 a and the cooling medium flow path 38. The passage width H1 of the inlet connection passage 52a1 is set to be larger than the passage width H2 of the inlet connection passage 52a2 (H1> H2).

  For this reason, in the inlet connection passage 52a1, the passage resistance is smaller than in the inlet connection passage 52a2, and the cooling medium easily flows. Therefore, the inlet connection passage 52a1 can increase the flow rate of the cooling medium supplied toward the inlet buffer shape portion 40a side of the cooling medium flow path 38 more than the flow rate of the cooling medium flowing through the inlet connection passage 52a2. .

  As a result, the cooling medium is reliably supplied to the central portion in the width direction of the cooling medium flow path 38 through the inlet buffer shape portion 40a, and it is possible to prevent the cooling water supply amount from being insufficient. For this reason, with a simple configuration, the temperature distribution and the humidity distribution can be made uniform over the entire area within the power generation surface, and the effect that the power generation performance can be easily improved is obtained.

  In addition, as shown in FIG. 6, the plurality of inlet connection passages 52a1 extend from the inlet buffer shape portion 40a of the cooling medium flow path 38 to the first wavy top portion P1 of the wave groove shape portion 34b (or the wave groove shape portion 30b). It is provided in between. Accordingly, the cooling medium supplied from the inlet connection passage 52a1 to the cooling medium flow path 38 side tends to generate an upward flow along the inclination of the wave groove shape portion 34b (or the wave groove shape portion 30b).

  As a result, the cooling medium can be smoothly guided to the inlet buffer shape portion 40 a and circulate through the inlet buffer shape portion 40 a, and can flow well in the center portion in the width direction of the cooling medium flow path 38. For this reason, it becomes possible to make temperature distribution and humidity distribution more uniform over the entire power generation surface.

  FIG. 7 is an enlarged explanatory view of a main part of the second metal separator 60 constituting the fuel cell according to the second embodiment of the present invention.

  In addition, the same referential mark is attached | subjected to the component same as the 2nd metal separator 16 which comprises the fuel cell 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  The second metal separator 60 is formed with a plurality of inlet connection passages 62a1 and 62a2 that connect the cooling medium supply communication hole 22a and the cooling medium flow path 38. The width dimension of the passage block 64a forming the inlet connection passage 62a1 on the inlet buffer shape portion 40a side is set smaller than the width dimension of the passage block 64b forming the inlet connection passage 62a2 on the side away from the inlet buffer shape portion 40a. By doing so, the cooling medium increasing portion is configured.

  In the second embodiment configured in this way, the passage width H1 of the inlet connection passage 62a1 is set larger than the passage width H2 of the inlet connection passage 62a2 by changing the shape of the passage blocks 64a and 64b. Yes. Therefore, the second embodiment can obtain the same effects as those of the first embodiment.

  FIG. 8 is an enlarged explanatory view of a main part of the second metal separator 70 constituting the fuel cell according to the third embodiment of the present invention.

  The second metal separator 70 is formed with a plurality of inlet connection passages 72a1 and 72a2 that allow the cooling medium supply communication hole 22a and the cooling medium flow path 38 to communicate with each other. By inclining the inlet connection passage 72a1 on the inlet buffer shape portion 40a side toward the inlet buffer shape portion 40a from the direction parallel to the inlet connection passage 72a2 on the side away from the inlet buffer shape portion 40a, the cooling medium increasing portion Is configured.

  In the third embodiment configured as described above, since the inlet connection passage 72a1 is inclined toward the inlet buffer shape portion 40a, the cooling medium passing through the inlet connection passage 72a1 is directed toward the inlet buffer shape portion 40a. Can be distributed securely. As a result, the cooling medium is smoothly guided to the inlet buffer shape portion 40a, flows through the inlet buffer shape portion 40a, and can flow favorably to the central portion in the width direction of the cooling medium flow path 38. The same effects as those of the first and second embodiments can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 11 ... Fuel cell stack 12 ... Electrolyte membrane and electrode structure 14, 16, 60, 70 ... Metal separator 18a ... Oxidant gas supply communication hole 18b ... Oxidant gas discharge communication hole 20a ... Fuel gas supply communication hole 20b ... Fuel gas discharge communication hole 22a ... Cooling medium supply communication hole 22b ... Cooling medium discharge communication hole 24 ... Solid polymer electrolyte membrane 26 ... Cathode side electrode 28 ... Anode side electrode 30 ... Oxidant gas flow path 30a, 34a ... Wave shape Projections 30b, 34b ... Wave groove-shaped part 34 ... Fuel gas flow path 38 ... Cooling medium flow path 42, 44 ... Seal members 46a, 46b, 50a, 50b ... Connection passages 52a1, 52a2, 62a1, 62a2, 72a1, 72a2 ... Inlet connection passage 52b ... Outlet connection passage 64a, 64b ... Passage block

Claims (4)

Sides to the pair of electrodes are provided the electrolyte electrode assembly of the electrolyte and a rectangular metal separator is stacked, first circulating the fuel gas and oxidizer gas in the stacking direction in the one longitudinal end portion of the metal separator while the fuel gas communication hole and the first oxidant gas passage is formed, a second fuel to circulate before Symbol fuel gas and the oxidant gas in the stacking direction to the longitudinal direction other end portion of the metal separator gas communication hole and the second oxidant gas passage is formed, the more short-side direction end portion of the metal separator, the first fuel gas communication hole and the first oxidant gas communication a pair of coolant supply passage for circulating a cooling medium prior to use in close proximity to through holes in the stacking direction, in proximity to the second fuel gas communication hole and the second oxidant gas passage A pair of cooling medium exhausts for circulating the used cooling medium in the stacking direction. A fuel cell and a communication hole is formed,
The surface of the metal separator towards one of the electrodes, in said first fuel gas communication hole and the second fuel gas communication hole, a fuel gas supply side through the inlet mouth buffer, and The fuel gas discharge side communicates with each other via the outlet buffer portion, and a wavy fuel gas flow path extending in the longitudinal direction is provided,
The surface of the metal separator toward the other of the electrodes, in said first oxidizer gas communication hole and the second oxidant gas communication hole, an oxidant gas supply side through the inlet mouth buffer And the oxidant gas discharge side communicates with each other through the outlet buffer portion, and a wave-shaped oxidant gas flow path extending in the longitudinal direction is provided,
Between the metal separators adjacent to each other, a wave groove shape portion formed on the back surface side of the fuel gas flow path and a wave groove shape portion formed on the back surface side of the oxidant gas flow path cause the cooling. A cooling medium flow path for circulating the medium is formed,
A plurality of inlet connection passages connecting the cooling medium supply communication hole and the cooling medium flow path;
The plurality of inlet connection passages are supplied toward the other portions with the flow rate of the cooling medium supplied toward the inlet buffer shape portion side that is the back surface shape of the inlet buffer portion of the cooling medium flow path. A fuel cell comprising a cooling medium increasing portion for increasing the flow rate of the cooling medium.   2. The fuel cell according to claim 1, wherein the cooling medium increasing portion has a passage width of the inlet connection passage on the inlet buffer shape portion side that is larger than a passage width of the inlet connection passage on the side away from the inlet buffer shape portion. A fuel cell characterized in that it is configured by setting a larger value.   2. The fuel cell according to claim 1, wherein the cooling medium increasing portion has the inlet connection passage on the inlet buffer shape portion side in a direction parallel to the inlet connection passage on the side away from the inlet buffer shape portion. A fuel cell characterized by being inclined to the buffer shape portion side.   4. The fuel cell according to claim 1, wherein the cooling medium increasing portion is provided between the inlet buffer shape portion and the first wave-like top portion of the cooling medium flow path. Fuel cell.

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