JP2008293835A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent bias of current density without increasing the size of a fuel cell. <P>SOLUTION: In the fuel cell configured by sandwiching gas diffusion layers 11 and 12 arranged on both sides of an electrolyte membrane 10 between separators 20 and 30, the cathode-side separator 30 includes: first gas passages 33 for passing a reaction gas therethrough while bringing it into contact with the gas diffusion layer 12; second gas passages 34 recessed in parallel to the first gas passages 33 from the most upstream parts of the first gas passages 33 to an area in front of the most downstream parts thereof, and for passing the reaction gas so as not to contact the gas diffusion layer 12; and communication parts 35 for passing the reaction gas from the downstream sides of the second gas passages 34 to the first gas passages 33. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an arrangement of gas flow paths for allowing reaction gas to flow in a fuel cell.

  In a fuel cell that reacts fuel gas and oxidant gas to convert chemical energy of fuel into electrical energy, an electrode catalyst layer, a gas diffusion layer, and a gas flow path are provided on both sides of the electrolyte membrane made of a solid polymer. A cell structure having a separator to be formed is known. In such a fuel cell, since the reaction gas supplied to the gas flow path is consumed by an electrochemical reaction, the concentration of the gas in the downstream part of the gas flow path is lower than that in the upstream part. Further, on the downstream side of the gas flow path, the flow of the reaction gas is inhibited by the condensed water generated by the reaction. As a result, the current density in the downstream portion of the gas flow path is lower than that in the upstream portion, and current density deviation occurs in the entire fuel cell.

In view of this, Japanese Patent Application Laid-Open No. H10-228688 discloses a technique for suppressing the bias of current density as described below. In Patent Document 1, a battery inlet manifold for introducing fuel gas or oxidant gas into a fuel cell is divided into two chambers, a gas inlet portion and a gas outlet portion, and a reaction gas is placed on the opposite side surface facing the battery inlet manifold. Provide a return manifold that makes a U-turn into the battery. Further, a bypass line is provided for bypassing the reaction gas from the gas pipe for supplying the reaction gas to the battery inlet manifold to the return manifold without passing through the fuel cell. As a result, among the reaction gases introduced into the fuel cell, the reaction gas that has flown through the half surface on the gas inlet side is sent to the half surface on the gas outlet side by the return manifold, and to the downstream portion of the gas flow path by the bypass line. Direct reaction gas is supplied.
Japanese Patent Laid-Open No. 6-188209

  However, in the above conventional fuel cell, it is necessary to provide a return manifold in the middle portion of the gas flow path, and further to provide a bypass passage for the supply gas.

  An object of the present invention is to suppress uneven current density without increasing the size of a fuel cell.

  The fuel cell of the present invention is a fuel cell configured by sandwiching gas diffusion layers disposed on both sides of an electrolyte membrane between a first separator and a second separator, and the first separator and the second separator. A first gas flow channel that is recessed and flows while contacting the reaction gas with the gas diffusion layer, and parallel to the first gas flow channel from the most upstream portion to the most downstream portion of the first gas flow channel. A second gas flow path that is recessed in at least one of the first separator and the second separator and that circulates the reaction gas so as not to contact the gas diffusion layer, and a downstream side of the second gas flow path. And a communication part for flowing the reaction gas to the first gas flow path.

  According to the present invention, the second gas flow path is provided in parallel with the first gas flow path from the most upstream part of the first gas flow path to the most downstream part of the first gas flow path. Since the reaction gas is circulated from the downstream side to the first gas channel, a part of the supplied reaction gas is directly supplied in the middle of the first gas channel, and the reaction in the upstream and downstream of the first gas channel is performed. The gas concentration can be leveled. Therefore, since the second gas flow path is provided in the same separator as the first gas flow path, it is possible to suppress a deviation in current density particularly at a high load without increasing the size of the fuel cell.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
The fuel cell of this embodiment is a polymer electrolyte fuel cell, and a cathode separator 30 (first separator) is formed by disposing a cathode gas diffusion layer 12 and an anode gas diffusion layer 11 on both sides of an electrolyte membrane 10 with a catalyst layer. And a plurality of unit cells sandwiched by the anode separator 20 (second separator). In this embodiment, the structure of the cathode separator is different from the conventional one.

  Here, in the conventional fuel cell, the reaction gas (oxygen) supplied to the cathode gas channel is consumed by an electrochemical reaction, and therefore the concentration of the reaction gas in the downstream portion of the gas channel is lower than that in the upstream portion. Further, condensed water is generated on the downstream side of the gas flow path, and the flow of the reaction gas is hindered. As a result, the current density on the downstream side of the gas flow path is lower than that on the upstream side, and this tendency becomes more prominent as the load increases (consumption of the reaction gas) (transport flux). The above problem becomes more prominent on the cathode side than on the anode side where hydrogen is used as a reaction gas.

  In addition, the temperature of the electrolyte membrane, the gas diffusion layer, and the like rises in the upstream portion of the gas flow path where the current density increases. Since these members are further deteriorated at higher temperatures, it is necessary to make the current density uniform in order to prevent the deterioration. Therefore, in this embodiment, the structure of the cathode separator 30 is set as follows to suppress the current density unevenness in the gas flow path.

  FIG. 1 is a plan view showing a surface of the cathode separator facing the gas diffusion layer. 2A is a cross-sectional view of the cross section of the single cell when cut along a plane A indicated by a one-dot chain line in FIG. 1, and FIG. 2B is a plane B indicated by a one-dot chain line in FIG. FIG. 2 (c) is a cross-sectional view of the single cell when cut in the direction of the arrow, and FIG. 2 (c) is a cross-section of the single cell when cut along the plane C indicated by the one-dot chain line in FIG. FIG.

  A first cathode gas flow path 33 (first gas flow path) is provided on the surface of the cathode separator 30 facing the cathode gas diffusion layer 12 so as to communicate from the cathode gas supply port 31 to the cathode gas discharge port 32. It is done. The first cathode gas flow path 33 circulates the cathode gas introduced from the cathode gas supply port 31, and discharges gas that has not been used for the reaction and water generated by the reaction to the cathode gas discharge port 32.

  On the surface of the cathode separator 30 opposite to the surface facing the gas diffusion layer 12, a second cathode gas flow path 34 (second gas flow path) is parallel to the first cathode gas flow path 33 of the cathode separator 30. It is recessed to the center. Further, a cathode gas communication hole 35 (communication portion) that communicates from the bottom of the second cathode gas flow channel 34 to the first cathode gas flow channel 33 is provided at the terminal portion of the second cathode gas flow channel 34. As a result, the second cathode gas channel 34 circulates the cathode gas introduced from the cathode gas supply port 31 without being subjected to the reaction, and is adjacent to the first cathode gas channel 34 through the cathode gas communication hole 35 at the terminal portion thereof. A cathode gas is introduced into the middle part of 33.

  Further, the anode separator 20 is provided with a recessed anode gas flow path 21 through which anode gas flows in a surface facing the anode gas diffusion layer 11, and a cooling water passage 13 through which cooling water flows through the opposite surface. Established.

  A shielding plate 14 is provided on the side of the cathode separator 30 where the second cathode gas flow path is provided. When the unit cells are stacked, the second cathode gas flow path 34 and the cooling water passage 13 of the adjacent cells are separated from the shielding plate 14. So as not to communicate with each other.

  The ratio of the cathode gas introduced from the cathode gas supply port 31 to the first cathode gas channel 33 and the second cathode gas channel 34 is divided into the first cathode gas channel 33 and the second cathode gas flow. By providing a difference in ventilation resistance corresponding to the passage 34 and the cathode gas communication hole 35, the design is optimized according to the operating conditions of the fuel cell, the specifications of the cathode gas diffusion layer 12, and the like.

  As described above, in the present embodiment, the second cathode gas channel 34 that does not open in the cathode gas diffusion layer 12 is provided in parallel with the first cathode gas channel 33, and the cathode gas (fresh air) having a high oxygen concentration is supplied to the cathode gas diffusion layer 12. Since a structure in which the terminal gas is supplied from the terminal portion to the first cathode gas channel 33 through the cathode gas communication hole 35, a part of the cathode gas is directly introduced into the first cathode gas channel 33. The oxygen concentration in the cathode gas in the upstream portion 33a and the downstream portion 33b of the gas flow path 30 is leveled, and the uneven current density can be suppressed particularly when the load is high.

  As a result, the reaction gas (oxygen) supplied to the cathode gas flow path generated in the conventional fuel cell is consumed by the electrochemical reaction, so that the reaction gas concentration downstream of the gas flow path is lower than the upstream portion. Thus, it is suppressed that condensed water is generated on the downstream side of the gas flow path and the flow of the reaction gas is hindered.

  In addition, since the current density on the downstream side of the gas flow path does not become lower than that on the upstream side, the effect of the present embodiment becomes more prominent as the load becomes high (reaction gas consumption (transport flow rate)). In particular, the above effect is more remarkable on the cathode side than on the anode side where hydrogen is used as the reaction gas.

  Further, in the upstream portion of the gas flow path where the current density increases, it is possible to suppress the temperature of the electrolyte membrane, the gas diffusion layer, and the like from rising, and it is possible to prevent the deterioration of these members due to high temperatures.

  As described above, in the present embodiment, by making the structure of the cathode separator 30 as described above, it is possible to suppress the uneven current density in the gas flow path.

  Further, since there is no need for a manifold in the middle of the cathode gas flow path or a bypass passage for supplying the cathode gas to the intermediate manifold, it is possible to suppress an uneven current density without increasing the size of the fuel cell.

(Second Embodiment)
FIG. 3 is a plan view showing a surface of the cathode separator facing the gas diffusion layer. 4A is a cross-sectional view when the cross section of the single cell is viewed from the direction of the arrow when cut along a plane A indicated by a dashed line in FIG. 3, and FIG. 4B is a plane B indicated by a dashed line in FIG. FIG. 4C is a cross-sectional view of the single cell when cut along the plane indicated by the arrow, and FIG. 4C is a cross-sectional view of the single cell when cut along plane C shown in FIG. FIG.

  In the present embodiment, the structure of the fuel cell in the first embodiment and the second cathode gas flow path 34 are different. The second cathode gas flow channel 34 of the present embodiment is recessed in parallel with the first cathode gas flow channel 33 from the upstream portion of the first cathode gas flow channel 33 to the most downstream portion of the first cathode gas flow channel 33. . At this time, as shown in FIGS. 4A and 4C, the second cathode gas passage 34 communicates with the most upstream portion of the first cathode gas passage 33 but does not communicate with the most downstream portion. Provided.

  In addition, a plurality of cathode gas communication holes 41 are provided from the center of the second cathode gas flow channel 34 corresponding to the downstream portion 33b of the first cathode gas flow channel 33 to the end portion. The cathode gas communication hole 41 does not directly communicate between the first cathode gas channel 33 and the second cathode gas channel 34 through the communication hole, but communicates from the second cathode gas channel 34 to the cathode gas diffusion layer. Thus, it is provided at the bottom of the second cathode gas flow path 34.

  Thereby, as shown in FIG. 4B, a plurality of cathode gases introduced into the second cathode gas channel 34 are provided on the surface (contact surface) of the cathode separator 30 facing the cathode gas diffusion layer 12. The gas is introduced into the first cathode gas flow path 33 through the gas communication holes 41 and through the holes in the cathode gas diffusion layer 12.

  The ratio of the cathode gas introduced from the cathode gas supply port 31 to be distributed to the first cathode gas channel 33 and the second cathode gas channel 34 is the same as in the first embodiment. By providing the flow resistance difference corresponding to the passage 33, the second cathode gas passage 34, and the cathode gas communication hole 41, the optimum design is made according to the operating conditions of the fuel cell, the specifications of the cathode gas diffusion layer 12, and the like.

  As described above, in the present embodiment, the cathode gas (fresh air) having a high oxygen concentration introduced into the second cathode gas channel 34 is passed from the cathode gas communication hole 41 through the cathode gas diffusion layer to the first cathode gas channel 33. As in the first embodiment, the oxygen concentration in the cathode gas at the upstream portion 33a and the downstream portion 33b of the first cathode gas flow channel 30 can be leveled, and the current density can be biased at high loads. Can be suppressed.

  The cathode gas supplied from the second cathode gas channel 34 to the downstream part 33b of the first cathode gas channel is between the second cathode gas channel 34 and the downstream part 33b of the first cathode gas channel. Since forced convection in the disposed cathode gas diffusion layer 12 can be performed, a cathode gas having a high oxygen concentration can be supplied to the catalyst layer provided alongside the cathode gas diffusion layer 12, and oxygen in the first cathode gas flow path 33 can be supplied. The power generation performance can be improved without being affected by a decrease in concentration or condensed water.

  Furthermore, since the cathode gas forcedly convection in the cathode gas diffusion layer 12 does not include the generated water (condensed water) generated by the reaction, the cathode gas diffusion layer 12, particularly to the portion where the convection flow rate of the cathode gas is reduced. It is possible to prevent a decrease in power generation performance due to condensate water retention. This also eliminates the need to supply a cathode gas that greatly exceeds the equivalence ratio due to the retention of condensed water, and thus increases the energy consumption of the gas supply device, and the net fuel cell system as a result of drying of the electrolyte membrane and catalyst layer. A decrease in output can be prevented.

(Third embodiment)
FIG. 5 is a plan view showing a surface of the cathode separator facing the gas diffusion layer. 6A is a cross-sectional view of the cross section of the single cell when cut along a plane A indicated by a dashed line in FIG. 5, and FIG. 6B is a plane B indicated by a dashed line in FIG. FIG. 6C is a cross-sectional view when the cross section of the single cell is cut from the direction of the arrow when cut by a line, and FIG. 6C is a cross section of the single cell when cut along the plane C indicated by the dashed line in FIG. FIG.

  The fuel cell of this embodiment is a so-called counter flow type fuel cell in which anode gas and cathode gas flow in different directions, and the structure of the second cathode gas flow path 34 is different from that of the second embodiment. The second cathode gas flow channel 34 of the present embodiment is recessed not to the most downstream portion 33c of the first cathode gas flow channel 33 but to the downstream portion 33b in front thereof. Further, the cathode gas communication hole 41 is provided from the center of the first cathode gas flow path 33 to the end portion of the downstream portion 33b.

  As a result, the cathode gas flowing through the second cathode gas flow channel 34 flows in the downstream portion 33b of the second cathode gas flow channel 34, that is, in the upstream portion excluding the most upstream portion of the anode gas flow channel 21, and the cathode gas communication hole 41 and The gas is introduced into the first cathode gas flow path 33 through the holes in the cathode gas diffusion layer 12.

  As described above, according to the present embodiment, the second cathode gas flow path 34 and the cathode gas communication hole 41 are not provided in the most downstream portion 33c of the first cathode gas flow path 33. In the cathode gas diffusion layer 12 of the cathode electrode facing the most upstream part which is the part, no forced convection of the cathode gas occurs, and the anode gas flow path 21 is supplied with a reaction gas that is not sufficiently humidified. However, drying of the electrolyte membrane 10 and the catalyst layer 10 caused by convection can be suppressed, and deterioration of power generation performance can be suppressed.

(Fourth embodiment)
FIG. 7 is a plan view showing a surface of the cathode separator facing the gas diffusion layer. 8A is a cross-sectional view of the cross section of the single cell when cut along a plane A indicated by a dashed line in FIG. 7, and FIG. 8B is a plane B indicated by a dashed line in FIG. FIG. 8C is a cross-sectional view when the cross section of the single cell is cut in the direction of the arrow when cut in FIG. 8, FIG. 8C is a cross section of the single cell when cut along the plane C indicated by the dashed line in FIG. FIG.

  In the present embodiment, the structure of the first cathode gas flow path 33 is different from the fuel cell shown in the second embodiment. The first cathode gas channel 33 of this embodiment is configured such that the channel width of the downstream portion 33b is narrower than the channel width of the upstream portion 33a.

  Here, in the first cathode gas flow channel upstream portion 33a for transporting the cathode gas mainly by diffusion in the gas diffusion layer, in order to transport the cathode gas uniformly by the catalyst layer 10, the cathode separator 30 and the cathode gas diffusion are used. It is desirable in terms of power generation performance to widen the opening width of the first cathode gas flow path 33 with respect to the cathode gas diffusion layer 12 within a range in which the electrical resistance between the layer 12 and the layer 12 does not increase greatly.

  Further, in the first cathode flow channel downstream portion 33b that transports the cathode gas mainly by forced convection in the gas diffusion layer, the opening width of the first cathode gas flow channel 33 with respect to the cathode gas diffusion layer 12 is narrowed to reduce the cathode gas. It is desirable to ensure the convection flow velocity of the cathode gas in the diffusion layer 12.

  Therefore, the opening width of the first cathode gas passage 33 with respect to the cathode gas diffusion layer 12 is wider than the downstream portion 33b in the first cathode gas passage upstream portion 33a, and the upstream portion 33a in the first cathode gas passage downstream portion 33b. Make it narrower.

  As described above, in this embodiment, the opening width of the first cathode gas flow path 33 with respect to the cathode gas diffusion layer 12 is relatively wide in the upstream portion 33a that transports the cathode gas mainly by diffusion in the gas diffusion layer. Since the downstream portion 33b that transports gas mainly by forced convection in the gas diffusion layer is configured to be relatively narrow, the power generation performance is better in both the upstream portion 33a and the downstream portion 33b of the first cathode gas flow path 33. As a result, the power generation performance of the entire cell can be improved, and the current density can be prevented from being biased.

(Fifth embodiment)
The fuel cell of this embodiment is obtained by replacing the separator with a corrugated separator in the fuel cell of the first embodiment. FIGS. 9A, 9B, and 9C are cross-sectional views of single cells corresponding to FIGS. 2A, 2B, and 2C of the first embodiment, respectively. That is, FIG. 9A shows a cross section of a single cell in the most upstream part of the first cathode gas flow path 33, FIG. 9B shows a cross section of the single cell in the center of the first cathode gas flow path 33, FIG. 9C shows a cross section of the single cell at the most downstream portion of the first cathode gas flow path 33.

  In a general fuel cell using a corrugated separator, a cooling water flow path is formed between the anode corrugated separator 50 and the cathode corrugated separator 60 between adjacent cells. In this embodiment, the shielding plate 14 is sandwiched therebetween. It is out. Thereby, the space formed between the cathode corrugated separator 60 and the shielding plate 14 becomes the second cathode gas flow path 34, and the space formed between the anode corrugated separator 50 and the shielding plate 14 is the cooling water flow path 13. It becomes.

  The space formed between the cathode corrugated separator 60 and the cathode gas diffusion layer 12 becomes the first cathode gas flow path 33, and the space formed between the anode corrugated separator 50 and the anode gas diffusion layer 11 is the anode. It becomes the gas flow path 21.

  The cathode corrugated separator 60 in the center of the first cathode gas flow path 33 is provided with a cathode gas communication hole 61 as shown in FIG. The cathode gas communication hole 61 is disposed on the surface of the cathode corrugated separator 60 that does not contact any of the cathode gas diffusion layer 12 and the shielding plate 14, and communicates the first cathode gas channel 33 and the second cathode gas channel 34. is doing.

  A closing member is provided on the downstream side of the portion of the second cathode gas passage 34 where the cathode gas communication hole 61 is provided, as shown in FIG. The discharge port 32 is not in direct communication. As a result, the cathode gas flowing through the second cathode gas flow channel 34 does not flow downstream from the cathode gas communication hole 61, but all flows from the cathode gas communication hole 61 to the first cathode gas flow channel 33.

  As described above, in the present embodiment, since the first cathode gas channel 33 and the second cathode gas channel 34 can be formed on both sides of the cathode corrugated separator 60, the thickness in the stacking direction per unit cell is set to the shielding plate. As in the first embodiment, it is possible to suppress the deviation in current density, with almost only increasing and only increasing.

(Sixth embodiment)
In the present embodiment, the cathode gas communication hole is different from that of the fifth embodiment. FIGS. 10A, 10B, and 10C are diagrams corresponding to FIGS. 4A, 4B, and 4C of the second embodiment, respectively. That is, FIG. 10A shows a cross section of a single cell in the most upstream portion of the first cathode gas flow path 33, FIG. 10B shows a cross section of the single cell in the center of the first cathode gas flow path 33, FIG. 10C shows a cross section of the single cell at the most downstream portion of the first cathode gas flow path 33.

  The cathode gas communication hole 63 of the present embodiment is disposed on the contact surface of the cathode corrugated separator 60 with the cathode gas diffusion layer 12. Also, a plurality of cathode gas communication holes 63 are provided along the flow direction of the cathode gas, as in the second embodiment. As a result, the cathode gas flowing through the second cathode gas channel 34 is introduced from the cathode gas communication hole 63 into the first cathode gas channel 33 through the cathode gas diffusion layer 12.

  As described above, in the present embodiment, since the first cathode gas channel 33 and the second cathode gas channel 34 can be formed on both sides of the cathode corrugated separator 60, the thickness in the stacking direction per unit cell is set to the shielding plate. As in the second embodiment, it is possible to suppress the deviation in current density, with almost only increasing and only increasing.

(Seventh embodiment)
The fuel cell of this embodiment is the same as the fuel cell of the second embodiment, but the structure of the cathode separator is different. FIGS. 11A, 11B, and 11C are diagrams corresponding to FIGS. 4A, 4B, and 4C of the second embodiment, respectively. That is, FIG. 11A shows a cross section of a single cell in the most upstream portion of the first cathode gas flow path 33, FIG. 11B shows a cross section of the single cell in the center of the first cathode gas flow path 33, FIG. 11C shows a cross section of the single cell at the most downstream portion of the first cathode gas flow path 33.

  In the present embodiment, the first cathode gas flow path 33 and the second cathode gas flow path 34 are recessed in parallel and alternately on the surface of the cathode separator 70 facing the cathode gas diffusion layer 12. Between the gas diffusion layer 12, a flat plate 15 with a slit is provided. The flat plate 15 with slits has slits 71 and 72 (openings) in part, opens the first cathode gas flow path 33 to the gas diffusion layer 12, and gas flow direction of the second cathode gas flow path 34 Only a part of the gas diffusion layer 12 is opened.

  In the upstream portion of the first cathode gas flow path 33, as shown in FIG. 11A, the flat plate 15 with slits is at a position facing the first cathode gas flow path 33, and the flow path groove of the first cathode gas flow path 33. The slit 71 has the same width as the opening width of the first.

  At the center of the first cathode gas flow path 33, the width of the slit 71 of the flat plate 15 with slit is set to be narrower than the opening width of the first cathode gas flow path 33, as shown in FIG. In addition, a slit 72 having a width narrower than the opening width of the second cathode gas flow channel 34 is provided in the slit plate 15 at a position facing the second cathode gas flow channel 34. As a result, the cathode gas flowing through the second cathode gas channel 34 is introduced into the first cathode gas channel 33 through the cathode gas diffusion layer 12 from the slit 72 of the flat plate 15 with slits.

  As shown in FIG. 11C, the second cathode gas channel 34 is not provided in the most downstream portion of the first cathode gas channel 33 as in the second embodiment, and the first cathode is provided on the slit-equipped plate 15. A slit 71 having the same width as that of the gas flow path 33 is provided.

  As described above, in the present embodiment, the first cathode gas channel 33 and the second cathode gas channel 34 are provided in parallel on one side of the cathode separator 70, and slits are provided so as to face both the channels 33 and 34. Since the flat plate 15 is provided, the shape of the opening of the first cathode gas flow path 33 and the second cathode gas flow path 34 to the cathode gas diffusion layer 12 is less restricted in manufacturing and cost, and the shape is designed with a high degree of freedom. be able to. Therefore, the opening shape of the first cathode gas flow path 33 to the cathode gas diffusion layer 12 can be optimized according to performance requirements, and the power generation performance can be further improved.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

  For example, in the above-described embodiment, the present invention is applied to the cathode gas flow path. However, the present invention may be applied only to the anode gas flow path or to both the anode gas flow path and the cathode gas flow path. May be.

  In the above-described embodiment, the polymer electrolyte fuel cell has been described as an example, but the present invention may be applied to other fuel cells.

It is a top view which shows the surface facing the gas diffusion layer of the cathode separator in 1st Embodiment. It is sectional drawing of FIG. It is a top view which shows the surface facing the gas diffusion layer of the cathode separator in 2nd Embodiment. FIG. 4 is a cross-sectional view of FIG. 3. It is a top view which shows the surface facing the gas diffusion layer of the cathode separator in 3rd Embodiment. It is sectional drawing of FIG. It is a top view which shows the surface facing the gas diffusion layer of the cathode separator in 4th Embodiment. It is sectional drawing of FIG. It is sectional drawing of the single cell in 5th Embodiment. It is sectional drawing of the single cell in 6th Embodiment. It is sectional drawing of the single cell in 7th Embodiment.

Explanation of symbols

10 Electrolyte membrane with catalyst layer 11 Anode gas diffusion layer (gas diffusion layer)
12 Cathode gas diffusion layer (gas diffusion layer)
20, 50 Anode separator (second separator)
30, 60, 70 Cathode separator (first separator)
33 First cathode gas flow path (first gas flow path)
34 Second cathode gas flow path (second gas flow path)
35, 41, 61, 63 Card gas communication hole (communication part)
71, 72 Slit (opening)

Claims (6)

In a fuel cell configured by sandwiching gas diffusion layers disposed on both sides of an electrolyte membrane by a first separator and a second separator,
A first gas flow path recessed in the first separator and the second separator and circulated while contacting a reaction gas with the gas diffusion layer;
A recess is provided in at least one of the first separator and the second separator in parallel with the first gas channel from the most upstream portion of the first gas channel to the most downstream portion. A second gas flow path for flowing gas so as not to contact the gas diffusion layer;
A communication part for allowing a reaction gas to flow from the downstream side of the second gas channel to the first gas channel;
A fuel cell comprising:   The communication portion communicates between the second gas flow path and the gas diffusion layer, and the first gas flow from the downstream side of the second gas flow path through the gas diffusion layer. The fuel cell according to claim 1, wherein the reaction gas is circulated through the passage. The fuel cell is a fuel cell in which reaction gas is allowed to flow in different directions between the first separator and the second separator,
The second gas flow path is provided in one of the first separator and the second separator,
The communication part is provided so as to circulate the reaction gas from the downstream side of the second gas flow path to a part other than the vicinity of the most downstream part of the first gas flow path through the gas diffusion layer. The fuel cell according to claim 2, wherein   Of the first gas flow path, the opening width of the portion corresponding to the portion where the communication portion is provided to the gas diffusion layer is larger than the opening width of the portion corresponding to the portion where the communication portion is not provided. The fuel cell according to claim 2, wherein the fuel cell is small. The first separator and the second separator are constituted by corrugated plates;
The first gas flow path is a flow path formed between the first separator and the second separator and the gas diffusion layer,
The second gas flow path is between at least one of the first separator and the second separator, and a flat plate provided in close contact with the opposite side of the gas diffusion layer of the at least one separator. The fuel cell according to any one of claims 1 to 4, wherein the fuel cell is formed. The first gas channel and the second gas channel are recessed in a surface facing at least one of the gas diffusion layer of the first separator and the second separator,
Between the at least one separator and the gas diffusion layer, further comprising a flat plate that shields openings of the first gas flow path and the second gas flow path,
The flat plate has an opening that opens the first gas flow path to the gas diffusion layer, and an opening that opens a part of the second gas flow path in the flow direction to the gas diffusion layer. The fuel cell according to any one of claims 2 to 4, wherein: