JP2008146897A - Fuel cell separator, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell separator and a fuel cell equipped with the same capable of surely exhausting condensed water generated on the surface of a gas diffusion electrode. <P>SOLUTION: The fuel cell separator is provided in contact with an electrolyte membrane-electrode assembly 9 made up by pinching a solid polymer electrolyte membrane having hydrogen ion conductivity with a pair of gas diffusion electrodes 6A, 6B. Gas flow channel grooves 21, 31 for circulating gas through are formed at a face on a side opposed to the gas diffusion electrodes 6A, 6B, and at bottom walls of the gas flow channel grooves 21, 31, convex parts 20A, 20B are provided extended toward the gas diffusion electrodes 6A, 6B, the convex parts 20A, 20B showing a higher hydrophilicity than the gas diffusion electrodes 6A, 6B. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell separator used in a fuel cell using a solid polymer electrolyte having hydrogen ion conductivity, and a fuel cell including the fuel cell separator.

  A fuel cell using a solid polymer electrolyte having hydrogen ion conductivity has an electric power and heat by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. It is generated at the same time. Such a fuel cell generally includes a polymer electrolyte membrane having hydrogen ion conductivity that selectively transports hydrogen ions, and a pair of gases disposed on both sides of the polymer electrolyte membrane so as to sandwich the polymer electrolyte membrane. And a diffusion electrode. This gas diffusion electrode is formed on the outer side of the catalyst layer mainly composed of conductive carbon powder carrying a platinum group metal catalyst, and has both air permeability and electronic conductivity. And a gas diffusion layer made of applied carbon paper or the like.

  As described above, the assembly of the polymer electrolyte membrane and the gas diffusion electrode is referred to as MEA (Membrane-Electrode-Assembly: electrolyte membrane-electrode assembly).

  A gas sealing material and a gasket are disposed on the periphery of the gas diffusion electrode with the polymer electrolyte membrane interposed therebetween. As a result, leakage of the gas supplied into the fuel cell to the outside and mixing of the fuel gas and the oxidant gas are prevented.

  Outside the MEA, a conductive separator for mechanically fixing the MEA and electrically connecting adjacent MEAs to each other in series is disposed. On the surface of the separator facing the MEA, there is formed a gas flow channel for supplying the reaction gas to the gas diffusion electrode and carrying away generated water, condensed water, and surplus gas. In addition, a heat medium flow channel for making the MEA have an appropriate temperature is formed on the opposite surface of the separator. In addition, a gas supply and discharge mechanism (manifold) for supplying gas to the gas flow channel groove formed in the separator and discharging the gas from the gas flow channel groove, and also supplying the heat medium to the heat medium flow channel In addition, a heat medium supply / discharge groove (manifold) for discharging the heat medium from the heat medium flow path groove is formed on the outer peripheral side of the separator facing the MEA.

  MEAs and separators configured as described above are alternately stacked to form a MEA group in which 10 to 200 cells are stacked. The MEA group is sandwiched between end plates via current collector plates and insulating plates, and both ends are fastened with fastening bolts. A laminated battery having a general structure can be obtained by fixing from above. This is called a cell stack.

  The polymer electrolyte membrane functions as a hydrogen ion conductive electrolyte by reducing the specific resistance of the membrane by containing water in a saturated state. Therefore, during operation of the fuel cell, the fuel gas and the oxidant gas are humidified and supplied in order to prevent evaporation of moisture from the polymer electrolyte membrane. In addition, during battery power generation, water as a reaction product is generated on the cathode side according to the following electrochemical reaction equation.

(Anode side) H ₂ → 2H ⁺ + 2e ⁻
(Cathode side) 2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O
The water in the humidified fuel gas and oxidant gas and the reaction product water are used to keep the electrolyte membrane in a saturated state. Excess water that has not been absorbed by the electrolyte membrane is discharged to the outside of the fuel cell together with excess fuel gas and oxidant gas as condensed water and water vapor.

  By the way, the fuel cell system is generally used in an operation mode in which the output is varied depending on the load in order to increase the energy efficiency. For this reason, in the case of operation at a low output, the amount of gas supplied decreases, and the condensate discharge power decreases accordingly. In this case, the condensed water clogs the gas diffusion electrode, and the phenomenon that the output becomes unstable due to insufficient supply of gas (flooding) occurs. How to suppress this flooding is a problem.

In order to efficiently discharge the condensed water on the gas diffusion electrode in order to suppress flooding, on the side wall surface of the gas flow channel groove formed in the separator, in a direction intersecting the gas flow direction, and There has been proposed a fuel cell in which a plurality of drain grooves are formed so that one end of the gas diffusion surface is desired, and condensed water generated in the flow path is absorbed by the drain grooves (see, for example, Patent Document 1).
JP 2002-343382 A

  However, in the case of the above-described conventional fuel cell, the drainage is performed by the drainage groove formed on the side wall surface (rib portion) of the gas flow channel groove of the separator, and therefore the drainage of the region in contact with the rib portion of the separator in the gas diffusion electrode. Although it is possible, the drainage of the area which is not in contact with the rib portion and is exposed to the gas flow channel groove was insufficient. In particular, when the gas flow rate slows down due to low power operation, it becomes difficult to discharge condensed water in the area exposed to the gas flow channel, resulting in insufficient gas supply to the gas diffusion electrode. There was a problem that the output became unstable.

  The present invention has been made to solve such problems, and its purpose is to reduce the amount of supplied gas for low output operation, and as a result, the condensed water generated on the surface of the gas diffusion electrode. An object of the present invention is to provide a fuel cell separator and a fuel cell including the fuel cell separator capable of efficiently discharging the condensed water even when the discharge force is reduced.

  In order to solve the above-described problems, a fuel cell separator according to the present invention is provided in contact with an electrolyte membrane-electrode assembly in which a solid polymer electrolyte membrane having hydrogen ion conductivity is sandwiched between a pair of gas diffusion electrodes. In the fuel cell separator in which a gas flow channel for allowing the gas to flow is formed on a surface facing the gas diffusion electrode, a bottom wall of the gas flow channel is formed on the gas diffusion electrode side. The convex part extended toward is provided, and the said convex part has higher hydrophilicity than the said gas diffusion electrode.

  By configuring in this way, even when the gas flow rate is lowered as in low power operation, the condensed water generated on the surface of the gas diffusion electrode can be easily discharged, so that flooding is avoided. Can do.

  In the fuel cell separator according to the above invention, the convex portion preferably has water absorption. For example, it is preferable that the convex portion is configured to suck up moisture including condensed water generated on the surface of the gas diffusion electrode by capillary action. Thereby, it is possible to reliably discharge the condensed water generated on the surface of the gas diffusion electrode.

  In the fuel cell separator according to the above invention, the convex portion is preferably made of nylon, polyethylene terephthalate, an electrolyte membrane, or porous carbon.

  In the fuel cell separator according to the invention, it is preferable that the convex portion is provided on the downstream side of the gas passage groove in the gas flow direction. This makes it possible to reliably discharge the condensed water on the gas diffusion electrode that tends to accumulate on the downstream side in the gas flow direction.

  The fuel cell of the present invention includes the fuel cell separator of the present invention configured as described above. By comprising in this way, the fuel cell which can fully suppress flooding can be obtained.

  According to the present invention, because of the low output operation, the amount of supplied gas is reduced, and as a result, the condensed water generated on the surface of the gas diffusion electrode is reduced in efficiency. Since the gas can be discharged well, the gas diffusion to the gas diffusion electrode is good and a stable output can be realized.

  In addition, even when the water repellency of the gas diffusion electrode deteriorates and the drainage of the surface of the gas diffusion electrode deteriorates, the portion of the condensed water exposed to the gas flow channel groove of the gas diffusion electrode can be efficiently removed. Stable output at the end of durability can be expected.

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

(Embodiment 1)
[Cell stack configuration]
FIG. 1 is a perspective view illustrating a configuration of a cell stack including a fuel cell including a separator according to Embodiment 1 of the present invention.

  As shown in FIG. 1, a cell stack 1 includes a cell stack 201 in which fuel cells (single cells) 2 having a plate-like overall structure are stacked in the thickness direction, and arranged at both ends of the cell stack 201. And a cell stack 201 and a fastening shaft (not shown) for fastening the end plates in the stacking direction of the single cells 2. The fastening shafts are inserted into fastening shaft holes 17 formed at the four corners of the cell stack 201 so as to penetrate the cell stack 201 in the stacking direction. A current collecting plate and an insulating plate are provided on both end plates, but they are not shown. The plate-like single cell 2 extends parallel to the vertical plane, and therefore the stacking direction of the single cells 2 is the horizontal direction.

  An oxidant gas supply manifold 13 is formed above one side portion (hereinafter referred to as a first side portion) of the cell stack 201 so as to penetrate the cell stack 201 in the stacking direction. Further, an oxidant gas discharge manifold 16 is formed below the other side portion (hereinafter referred to as a second side portion) of the cell stack 201 so as to penetrate the cell stack 105 in the stacking direction. .

  A fuel gas supply manifold 12 is formed above the second side portion of the cell stack 201 so as to penetrate the cell stack 201 in the stacking direction. A fuel gas discharge manifold 15 is formed below the first side portion of the cell stack 201 so as to penetrate the cell stack 105 in the stacking direction.

  A cooling fluid supply manifold 11 is formed above and inside the oxidant gas supply manifold 13 so as to penetrate the cell stack 201 in the stacking direction. A cooling fluid discharge manifold 14 is formed below and inside the oxidant gas discharge manifold 16 so as to penetrate the cell stack 201 in the stacking direction.

[Single cell configuration]
FIG. 2 is a cross-sectional view showing a configuration of a fuel cell (single cell) 2 provided with the separator according to Embodiment 1 of the present invention when viewed from the direction of arrows II-II in FIG.

  As shown in FIG. 2, the single cell 2 includes an MEA 9 and a pair of conductive separators 10 </ b> A and 10 </ b> B provided in contact with the MEA 9.

  The MEA 9 includes a polymer electrolyte membrane 3 and a pair of gas diffusion electrodes 6A and 6B configured to be laminated on both surfaces thereof. Specifically, the MEA 9 includes a pair of gas diffusions formed on both surfaces of the polymer electrolyte membrane 3 made of an ion exchange membrane that selectively permeates hydrogen ions and the inner side of the periphery of the polymer electrolyte membrane 3. Electrodes 6A and 6B are provided.

  The gas diffusion electrodes 6A and 6B include a pair of an anode side catalyst layer 4A and a cathode side catalyst layer 4B mainly composed of carbon powder supporting a platinum (Pt) -based metal catalyst, and a pair of the catalyst layers 4A and 4B. A pair of anode-side gas diffusion layers 5A and cathode-side gas diffusion layers 5B disposed on the outer surface are provided. Here, the gas diffusion layers 5A and 5B have a porous structure so as to have both air permeability and electronic conductivity. Thereby, the gas diffusion electrode 6A composed of the anode side catalyst layer 4A and the anode side gas diffusion layer 5A functions as an anode electrode, and the gas diffusion electrode 6B composed of the cathode side catalyst layer 4B and the cathode side gas diffusion layer 5B. Functions as a cathode electrode. Therefore, hereinafter, the gas diffusion electrode 6A is referred to as an anode electrode 6A, and the gas diffusion electrode 6B is referred to as a cathode electrode 6B.

  The polymer electrolyte membrane 3 is preferably a membrane made of perfluorosulfonic acid. For example, a DuPont Nafion (registered trademark) membrane is used. The MEA 5 is generally manufactured by forming the catalyst layers 4A and 4B and the gas diffusion layers 5A and 5B on the polymer electrolyte membrane 3 by a method such as sequential application, transfer, and hot pressing. Or the commercial item of MEA9 manufactured in this way can also be utilized.

  A gasket 7 is disposed on the periphery of the anode electrode 6A and the cathode electrode 6B with the polymer electrolyte membrane 1 interposed therebetween.

  A fuel gas flow channel 21 for supplying fuel gas to the anode electrode 6A is formed on the surface of the separator 10A facing the anode electrode 6A, and the flow of cooling fluid is formed on the other surface. A cooling fluid passage groove 26 constituting the passage is formed.

  Further, an oxidant gas flow channel 31 for supplying an oxidant gas to the cathode electrode 6B is formed on the surface of the separator 10B facing the cathode electrode 6B, and the other surface is formed with A cooling fluid channel groove 36 that forms a cooling fluid channel is formed.

  In the cell stack 1 formed by stacking the single cells 2, a cooling fluid is provided between the cathode-side separator 10 </ b> B of one single cell 2 and the anode-side separator 10 </ b> A of the single cell 2 adjacent to the single cell 2. A cooling part constituted by the flow channel grooves 26 and 36 is formed.

  On the bottom wall of the fuel gas channel groove 21 formed in the anode-side separator 10A, a convex portion 20A extending toward the anode electrode 6A is provided. Similarly, a convex portion 20B extending toward the cathode electrode 6B is provided on the bottom wall of the fuel gas passage groove 31 formed in the cathode-side separator 10B.

  Here, the heights of the protrusions 20A and 20B are set according to the size of the droplets generated on the surfaces of the anode electrode 6A and the cathode electrode 6B. Specifically, the size of the droplets generated on the surface of the gas diffusion electrode varies depending on the specifications and usage conditions of the fuel cell, but the size of the droplets estimated based on them varies depending on the surface of the gas diffusion electrode. When this occurs, the protrusions 20A and 20B have such a height that they touch the droplets. With this configuration, as will be described later, droplets generated on the surface of the gas diffusion electrode flow along the convex portions 20A and 20B.

  These convex portions 20A and 20B have hydrophilicity. Here, the fact that the convex portions 20A and 20B are hydrophilic means that the contact angle between the convex portions 20A and 20B and water is 90 degrees or less.

  Specifically, the protrusions 20A and 20B are made of a polyethylene terephthalate (PET) film subjected to a corona discharge surface treatment. The surface treatment may be performed by, for example, plasma discharge or UV light other than by corona discharge.

  The convex portions 20A and 20B have higher hydrophilicity than the anode electrode 6A and the cathode electrode 6B. The hydrophilicity of the anode electrode 6A and the cathode electrode 6B can change with power generation, but the state in which the hydrophilicity of the convex portions 20A and 20B is higher than the hydrophilicity of the anode electrode 6A and the cathode electrode 6B is as follows: Always kept.

[Detailed configuration of separator]
3A and 3B are plan views showing the configuration of the separator according to Embodiment 1 of the present invention, where FIG. 3A is a plan view showing the configuration of the anode-side separator 10A, and FIG. 3B is the configuration of the cathode-side separator 10B. FIG. FIG. 4 is an enlarged perspective view showing a region 50 in FIG.

  As shown in FIGS. 3A and 3B, the separators 10A and 10B include the above-described cooling fluid supply manifold 11, fuel gas supply manifold 12, oxidant gas supply manifold 13, cooling fluid discharge manifold 14, and fuel gas. A cooling fluid supply manifold hole 41, a fuel gas supply manifold hole 42, an oxidant gas supply manifold hole 43, and a cooling fluid discharge manifold hole 44 constituting the discharge manifold 15, the oxidant gas discharge manifold 16, and the fastening shaft hole 17, respectively. A fuel gas discharge manifold hole 45, an oxidant gas discharge manifold hole 46, and a shaft hole 47 are formed.

  As shown in FIG. 3A, the separator 10A has a fuel gas channel groove 21 formed on the main surface facing the anode electrode. The fuel gas channel groove 21 is formed in a serpentine shape so as to reach the fuel gas discharge manifold hole 45 from the fuel gas supply manifold hole 42.

  As shown in FIG. 3B, the separator 10B has an oxidant gas flow channel 31 formed on the main surface facing the cathode electrode. The oxidant gas passage groove 31 is formed in a serpentine shape so as to reach from the oxidant gas supply manifold hole 43 to the oxidant gas discharge manifold hole 46.

  As described above, the convex portion 20A is formed in the fuel gas passage groove 21, and the convex portion 20B is formed in the oxidant gas passage groove 31. As shown in FIG. 4, these protrusions 20A and 20B are formed on the gas diffusion electrode side from the substantially central position in the width direction of the bottom walls of the fuel gas passage groove 21 and the oxidant gas passage groove 31. It is provided so as to extend in the direction of heading.

[Discharge of condensed water]
In the case of the fuel cell of the present invention configured as described above, the condensed water on the gas diffusion electrode can be efficiently discharged. This will be described in comparison with a conventional fuel cell in which no convex portion is provided in the gas flow channel groove.

  FIG. 5 is an explanatory diagram showing the behavior of the condensed water on the gas diffusion electrode, where (a) is a conceptual diagram showing the behavior of the condensed water in the case of a conventional fuel cell, and (b) is the fuel cell of the present invention. It is a conceptual diagram which shows the behavior of the condensed water in the case of. FIG. 5A shows only the gas diffusion layer constituting the gas diffusion electrode and the separator provided in contact with the gas diffusion electrode. FIG. 5B shows only the gas diffusion layer 5A constituting the anode electrode described above and the anode-side separator 10A provided in contact with the anode electrode.

  As shown in FIG. 5A, in the case of a conventional fuel cell, the separator 71 has a gas flow channel groove 72 formed on one main surface and a cooling fluid flow channel groove 73 formed on the other main surface. Yes. Unlike the case of the present invention, the gas channel groove 72 is not provided with a convex portion.

  In the conventional fuel cell configured as described above, when the low power operation in which the gas flow rate is reduced is performed, it is not sufficient to remove the condensed water droplet 60 generated on the surface of the gas diffusion layer 70 constituting the gas diffusion electrode. However, the condensed water tends to block the gas diffusion electrode. As a result, a stable output cannot be obtained in low output operation.

  On the other hand, as shown in FIG. 5B, in the case of the fuel cell of the present invention, the fuel gas flow channel groove 21 formed in the separator 10A is provided with a convex portion 20A extending toward the anode electrode, Thereby, the condensed water on the anode electrode can be easily discharged. That is, the condensed water droplet 60 generated on the surface of the gas diffusion layer 5A constituting the anode electrode travels along the convex portion 20A having higher hydrophilicity than the gas diffusion layer 5A, and is on the bottom wall side of the fuel gas channel 21. It will move to and will be discharged. Therefore, even when the gas flow rate is lowered due to low output operation, the condensed water on the gas diffusion electrode can be sufficiently discharged, so that stable output can be obtained without causing flooding. .

  Further, it goes without saying that the condensed water on the gas diffusion electrode can also be discharged by the convex portion 20B provided on the bottom wall of the oxidant gas flow channel 31 in the cathode-side separator 10B in the same manner.

(Embodiment 2)
FIG. 6 is a cross-sectional view showing a configuration of a fuel cell including the separator according to Embodiment 2 of the present invention. In addition, since it is the same as that of the case of Embodiment 1 about structures other than the convex part provided in the bottom wall of the gas flow path groove | channel formed in the separator, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 6, the bottom wall of the fuel gas passage groove 21 formed in the anode separator 10A is provided with a convex portion 20C extending toward the anode electrode 6A. Unlike the convex portion 20 </ b> A in the first embodiment, the convex portion 20 </ b> C is disposed so as to be in contact with one side wall of the fuel gas flow channel groove 21.

  Similarly, a convex portion 20D extending toward the cathode electrode 6B is provided on the bottom wall of the oxidant gas flow channel groove 31 formed in the cathode-side separator 10B. The oxidant gas passage groove 31 is disposed so as to be in contact with one side wall.

  As described above, the convex portion provided on the bottom wall of the gas flow channel groove formed in the separator is not the substantially center position in the width direction of the gas flow channel groove as in the first embodiment, but other than that. Even if it is provided so as to extend from the position toward the gas diffusion electrode, it is possible to improve the drainage of condensed water on the gas diffusion electrode in the same manner as in the first embodiment.

(Embodiment 3)
FIG. 7 is a cross-sectional view showing a configuration of a fuel cell including a separator according to Embodiment 3 of the present invention. In addition, since it is the same as that of the case of Embodiment 1 about structures other than the convex part provided in the bottom wall of the gas flow path groove | channel formed in the separator, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 7, the fuel gas channel groove 21 formed in the anode-side separator 10A is provided with a convex portion 20E extending toward the anode electrode 6A, and the cathode-side separator 10B has The formed oxidant gas channel groove 31 is provided with a convex portion 20F extending toward the cathode electrode 6B.

  Here, each of these convex portions 20E and 20F is fixed to the fuel gas flow channel groove 21 and the oxidant gas flow channel groove 31 until the plurality of stacked unit cells 2 are fixed by the fastening shaft. It has not been. When the plurality of stacked unit cells 2 are fixed by the fastening shaft, the gas diffusion layer 5A constituting the anode electrode 6A and the gas diffusion layer 5B constituting the cathode electrode 6B are respectively connected to the fuel gas flow path. As a result, the protrusions 20E and 20F are fixed to the fuel gas channel groove 21 and the oxidant gas channel groove 31 as shown in FIG. Will be.

  As described above, the convex portion provided on the bottom wall of the gas flow channel groove formed in the separator does not necessarily have to be integrated with the separator. When the plurality of stacked unit cells 2 are fixed, You may be comprised so that it may fix to a flow-path groove | channel.

(Embodiment 4)
8A and 8B are plan views showing the configuration of the separator according to Embodiment 4 of the present invention, where FIG. 8A is a plan view showing the configuration of the anode-side separator 10A, and FIG. 8B is the configuration of the cathode-side separator 10B. FIG. In addition, since it is the same as that of the case of Embodiment 1 about structures other than the convex part provided in the bottom wall of the gas flow path groove | channel formed in the separator, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the case of the first embodiment, as shown in FIGS. 3A and 3B and the like, the convex portions 20A and 20B extend over the entire region from the upstream side to the downstream side in the gas flow direction. It is provided on the bottom wall of the oxidant gas channel groove 31.

  On the other hand, in the fourth embodiment, as shown in FIGS. 8A and 8B, the convex portions 20A and 20B are provided only on the downstream side in the gas flow direction. Here, the downstream side in the gas flow direction means a region downstream from a substantially middle point of the gas flow channel groove formed in a serpentine shape.

  When the drainage of the condensed water generated on the surface of the gas diffusion electrode is not sufficient, the condensed water tends to accumulate on the downstream side in the gas flow direction. Therefore, it is desirable that the convex portions 20A and 20B that promote the discharge of the condensed water are provided on the downstream side in the gas flow direction of the gas passage groove as in the present embodiment.

  In addition to the configuration in which the convex portion is provided on the downstream side in the gas flow direction of the gas flow channel groove, for example, the size and / or material of the convex portion is made different between the upstream side and the downstream side. Such a configuration may be adopted.

(Other embodiments)
As described above, in the first embodiment, the convex portion provided on the bottom wall of the gas flow channel groove formed in the separator is composed of a polyethylene terephthalate (PET) film subjected to corona discharge surface treatment. However, the present invention is not limited to this, and the convex portion can be formed from other materials.

  For example, the convex portion may be made of nylon, electrolyte membrane, porous carbon, or the like that has been similarly surface-treated.

  Here, when the convex portion is formed using an electrolyte membrane having a higher moisture content than other materials, the electrolyte membrane contains moisture, and the moisture is released into the gas flow channel groove of the separator. As a result, the gas channel groove is in a high humidity state, and as a result, drying of the MEA is prevented. As described above, the condensed water is more likely to collect on the downstream side in the gas flow direction than on the upstream side, in other words, the upstream side in the gas flow direction tends to be more dry than the downstream side. is there. Therefore, when the convex portion is formed using the electrolyte membrane, the convex portion is preferably provided on the upstream side in the gas flow direction.

  Moreover, when this convex part has a water absorption property, the condensed water generated on the surface of the gas diffusion electrode can be reliably discharged. Therefore, it is preferable that the convex part has water absorption. As a specific configuration, the convex portion may be configured such that the member itself absorbs water, or configured so that water can be sucked up by capillary action.

  In addition, when the member which comprises a convex part swells, it can become a cause which enlarges the channel resistance in a gas channel groove. Therefore, it is preferable that it does not swell as much as possible.

  The separator for fuel cell and the fuel cell of the present invention are excellent in output stability particularly during low-power operation by efficiently discharging the condensed water on the gas diffusion electrode, and can be used for household cogeneration systems and motorcycles. It is useful as a fuel cell separator and fuel cell for use in electric vehicles, hybrid electric vehicles, and the like.

It is a perspective view which shows the structure of the cell stack which consists of a fuel cell provided with the separator which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the fuel cell (single cell) provided with the separator which concerns on Embodiment 1 of this invention at the time of seeing from the direction of the II-II arrow line of FIG. It is a top view which shows the structure of the separator which concerns on Embodiment 1 of this invention, (a) is a top view which shows the structure of the anode side separator, (b) is a top view which shows the structure of the cathode side separator. . It is a perspective view which expands and shows the area | region specified in FIG.3 (b). It is explanatory drawing which shows the behavior of the condensed water on a gas diffusion electrode, Comprising: (a) is a conceptual diagram which shows the behavior of the condensed water in the case of the conventional fuel cell, (b) is the condensation in the case of the fuel cell of this invention It is a conceptual diagram which shows the behavior of water. It is sectional drawing which shows the structure of the fuel cell provided with the separator which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the fuel cell provided with the separator which concerns on Embodiment 3 of this invention. It is a top view which shows the structure of the separator which concerns on Embodiment 4 of this invention, (a) is a top view which shows the structure of the anode side separator, (b) is a top view which shows the structure of the cathode side separator. .

Explanation of symbols

1 Cell stack 2 Fuel cell (single cell)
3 Polymer Electrolyte Membrane 4A, 4B Catalyst Layer 5A, 5B Gas Diffusion Layer 6A, 6B Gas Diffusion Electrode 7 Gasket 9 MEA
10A, 10B Separator 20A-20F Protrusion 21 Fuel gas flow path groove 31 Oxidant gas flow path groove 41 Cooling fluid supply manifold hole 42 Fuel gas supply manifold hole 43 Oxidant gas supply manifold hole 44 Cooling fluid discharge manifold hole 45 Fuel gas Discharge manifold hole 46 Oxidant gas discharge manifold hole 47 Shaft hole 201 Cell stack

Claims (6)

A gas channel groove provided to abut on an electrolyte membrane-electrode assembly formed by sandwiching a solid polymer electrolyte membrane having hydrogen ion conductivity between a pair of gas diffusion electrodes, and for flowing gas, and the gas diffusion electrode In the fuel cell separator formed on the opposite surface,
The bottom wall of the gas channel groove is provided with a convex portion extending toward the gas diffusion electrode side,
The separator for a fuel cell, wherein the convex portion has higher hydrophilicity than the gas diffusion electrode.   The fuel cell separator according to claim 1, wherein the convex portion has water absorption.   The fuel cell separator according to claim 2, wherein the convex portion is configured to be able to suck up moisture including condensed water generated on the surface of the gas diffusion electrode by capillary action.   2. The fuel cell separator according to claim 1, wherein the convex portion is made of nylon, polyethylene terephthalate, an electrolyte membrane, or porous carbon.   2. The fuel cell separator according to claim 1, wherein the convex portion is provided on a downstream side of the gas passage groove in a gas flow direction.   A fuel cell comprising the fuel cell separator according to any one of claims 1 to 5.

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