JP2013097872A - Fuel cell separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a fuel cell of a latent heat cooling type, which uses a porous gas flow path having high cooling efficiency and capable of stably generating power, and to provide the fuel cell.SOLUTION: A fuel cell separator has an oxidizer side porous gas flow path 5 arranged on one face of a metal plate 3 and a fuel side porous gas flow path 4 arranged on the other face. The metal plate 3 includes an oxidizer supply manifold 13 for supplying oxidant gas to the oxidizer side porous gas flow path 5, and a cooling water supply manifold 15 for supplying cooling water to the oxidizer side porous gas flow path 5. The cooling water supply manifold 15 is provided between the oxidizer supply manifold 13 and the oxidizer side porous gas flow path 5. A sealing member 7 for preventing the mixture of the oxidant gas and the cooling water is provided at a boundary part of the oxidizer supply manifold 13 and the cooling water supply manifold 15.

Description

  The present invention relates to a separator used in a fuel cell that generates electrical energy by a chemical reaction between a fuel and an oxidant.

  Various types of fuel cells have been put into practical use depending on the type of electrolyte. For example, a polymer electrolyte fuel cell has a membrane electrode assembly in which a solid polymer electrolyte membrane and both sides thereof are covered with a fuel electrode catalyst layer (hereinafter referred to as an anode) and an oxidant electrode catalyst layer (hereinafter referred to as a cathode). Both sides are sandwiched between gas diffusion layers made of porous carbon material. Further, a plurality of unit power generation cells configured by arranging separators for supplying fuel gas and oxidant gas on both sides are stacked to form a stacked body (hereinafter referred to as a stack), and both ends of the stack are tightened. A fuel cell stack is formed by fastening with a plate or the like.

  The separator generally has a flow path for fuel gas or oxidant gas on one side and a cooling medium flow path on the other side. For example, a metal thin plate is formed with unevenness by pressing. It is manufactured by. In the case of a fuel cell using this separator, the convex surface (hereinafter referred to as a rib) of the fuel gas channel is in contact with the gas diffusion layer on the anode side, and the rib of the oxidant gas channel is in contact with the cathode side. At this contact portion, electrons generated by the reaction are exchanged, and heat generated by the electrochemical reaction is transmitted to the cooling medium flowing in the cooling flow path. Further, the fuel gas and the oxidant gas flow through the recess and are supplied to the electrode catalyst through the gas diffusion layer.

  Fuel cells are being put to practical use in stationary distributed power sources and in-vehicle power sources because of their higher efficiency and lower environmental impact than other power sources. For example, in the case of an in-vehicle power supply, high output density such as small size and light weight is required. For this purpose, it is necessary to generate power uniformly over the entire power generation surface and to reduce parts that do not directly contribute to power generation. An example of a component that does not directly contribute to power generation is a cooling channel. On the other hand, a latent heat cooling type fuel cell in which the cooling flow path is omitted, water is supplied to the gas flow path together with the reaction gas, and the unit power generation cell is cooled using the latent heat when the water evaporates has been studied. Yes. In a latent heat cooling type fuel cell, it is important to uniformly supply reaction gas and water to the gas flow path in order to generate power uniformly over the entire power generation surface. For example, in Patent Document 1, water is introduced from a water supply manifold to a porous body of a buffer portion formed on the back surface of a fuel gas supply surface of a separator in order to distribute a mixed fluid of fuel gas and water evenly. A method is shown in which water is supplied to the fuel gas supply groove through a communication hole communicating the material and the fuel gas supply groove.

JP 2001-283879 A

  In conventional separators, the reaction gas flow path was formed by pressing a thin metal plate or molding a carbon material. However, the rib is in contact with the gas diffusion layer and only plays a role, and the flow path is responsible for gas diffusion. Are divided, and the distribution of the current-carrying portion and the gas diffusion portion is caused by the size of the rib and the flow path width. It is effective to subdivide the width of the rib and the flow path to make the power generation uniform, but there is a limit to the subdivision from the viewpoint of processing. Instead of such a press-worked separator, a method of using a conductive porous body with communicating pores in the reaction gas channel is conceivable. That is, when the porous body is used, the skeleton portion of the porous body, which is the energized portion, and the communication pores of the gas diffusion portion can be mixed and made uniform. As a result, the power generation reaction is made uniform, and an improvement in output can be expected.

  Further, it is preferable to use a porous gas flow path from the viewpoint of latent heat cooling. That is, the specific surface area of the porous gas channel is significantly increased compared to the groove channel, and as a result, the contact area between the water and the gas channel is increased, thereby enhancing the cooling effect due to water evaporation. be able to.

  On the other hand, in order to realize latent heat cooling using the porous gas channel, a method of supplying water to the porous gas channel for uniformly supplying gas and water into the pores of the porous body Is important.

  In the latent heat cooling type fuel cell disclosed in Patent Document 1, a groove channel formed by molding a carbon material is used as a separator, and a porous gas channel has not been studied.

  An object of the present invention is to provide a separator for a fuel cell of a latent heat cooling system and a fuel cell using a porous gas channel having high cooling efficiency and capable of generating stable power.

  The fuel cell separator of the present invention has a configuration in which an oxidant-side porous gas channel is disposed on one surface of a metal plate and a fuel-side porous gas channel is disposed on the other surface. An oxidant supply manifold for supplying oxidant gas to the side porous gas flow path, and a cooling water manifold for supplying cooling water to the oxidant side porous gas flow path, wherein the cooling water manifold is A seal provided between the oxidant supply manifold and the oxidant side porous gas flow path to prevent mixing of oxidant gas and cooling water at the boundary between the oxidant supply manifold and the cooling water manifold A member is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the separator for fuel cells and a fuel cell of a latent heat cooling system using the porous gas flow path with high cooling efficiency and stable electric power generation can be provided.

The schematic diagram of the cross section of the fuel cell stack concerning this invention. The top view and sectional drawing of the fuel cell separator concerning this invention. The disassembled perspective view of the fuel cell stack concerning this invention. The schematic diagram of the cell cross section of the oxidant manifold and cooling-medium supply manifold vicinity of the fuel cell stack concerning this invention. The schematic diagram which shows the oxidizing gas and cooling water supply system of the fuel cell system of this invention. The top view which shows the modification of the fuel cell separator concerning this invention.

  Hereinafter, examples of the fuel cell of the present invention will be described with reference to the drawings.

Example 1
FIG. 1 is a schematic cross-sectional view of a fuel cell stack 100 of this embodiment. The fuel cell stack 100 includes a fuel gas supply port 111 for supplying fuel gas to the stack, a fuel gas discharge port 112 for discharging fuel exhaust gas from the stack, an oxidant gas supply port 113 for supplying oxidant gas to the stack, and oxidation from the stack. Oxidant gas discharge port 114 for discharging the agent exhaust gas, cooling water supply port 117 for supplying cooling water to the stack, current collecting plate 115 for taking out electric power to the outside, insulating plate 116 arranged outside the current collecting plate 115 The power generation unit 105 includes a seal member 6 for preventing leakage of reaction gas, an end plate 118 having a reaction gas supply or discharge port, and a power generation unit 105. Although not shown, a mechanism for applying a load in the stacking direction of the stack constituent members is provided so that a surface pressure of about 1 MPa is applied to the electrolyte membrane / electrode catalyst assembly 1.

  The power generation unit 105 includes a membrane electrode assembly 1 in which an anode catalyst is formed on one surface of an electrolyte membrane and a cathode catalyst formed on the other surface, and a fuel-side porous gas channel on one surface of a metal plate 3. 4 and a separator in which the oxidant side porous gas flow path 5 is arranged on the other surface are alternately laminated. In the fuel cell stack 100 shown in FIG. 1, a gas diffusion layer 2 made of carbon paper or carbon felt is disposed between the membrane electrode assembly 1 and the porous gas flow path. Here, the metal plate 3, the fuel side porous gas flow path 4, the gas diffusion layer 2, the membrane electrode assembly 1, the gas diffusion layer 2, the oxidant side porous gas flow path 5, and the metal plate 3 are laminated in this order. This structure is a unit power generation cell, and a plurality of unit power generation cells are stacked in series. Although not shown, the power generation unit 105 is formed with manifolds connected to the supply ports and discharge ports, and supply and discharge of reaction gas and cooling water from each manifold to each unit power generation cell. Done. The gas diffusion layer 2 may be omitted when the porous gas flow path has the function of the gas diffusion layer 2.

  The membrane electrode assembly 1 includes a solid polymer electrolyte membrane made of a fluorine-based or hydrocarbon-based solid polymer material, and an anode and a cathode made of a carbon paste carrying a catalyst such as platinum.

  As the metal plate 3 constituting the separator, a pure metal or alloy having a thickness of 0.2 mm or less, or a flat plate made of a clad material obtained by laminating and rolling a plurality of these metal plates is used. Examples of the material include titanium, SUS, aluminum, and magnesium.

The porous bodies constituting the fuel-side porous gas flow path 4 and the oxidant-side porous gas flow path 5 are continuous pores made of a metal material. The material is selected from titanium, aluminum, magnesium, nickel, chromium, molybdenum, and alloys such as SUS partially containing these. It is preferably produced by foaming, sintering, or binding of fine metal fibers, and the porosity is preferably 75% or more. The pore diameter of the porous body is preferably in the range of 10 μm to 1500 μm, and the mode diameter based on the pore diameter distribution is particularly preferably 150 μm or more.
The porous body may have a thickness of 0.2 mm to 1.5 mm, and only the pores of the porous body may be used as a gas diffusion channel, but a groove having a width or depth larger than the pore diameter is provided on one surface. Alternatively, pressure loss can be reduced by providing a flow path having a diameter larger than the mode diameter of the pores inside the porous body.

  In addition to a metal material such as SUS, an insulating resin such as PPS (Poly Phenylene Sulfide) can also be used for the end plate 119. In the case where an insulating resin is used for the end plate 119, a structure serving as both the insulating plate 116 and the end plate may be employed. The current collecting plate 115 is a conductive terminal for taking out the electric energy generated by the fuel cell to the outside. For example, it is possible to achieve both corrosion resistance and conductivity by using a current collector plate 115 that is gold-plated on copper.

  In the fuel cell stack 100 of the present embodiment, the cooling water supply port 117 is connected to the oxidant side porous gas flow path 5 of each unit power generation cell via a cooling water manifold in the stack. The cooling water flows from the cooling water supply port 117 through the cooling water manifold and is supplied to the oxidant-side porous gas channel 5 of each unit power generation cell. In the oxidant-side porous gas flow path 5, cooling water is supplied together with the oxidant gas supplied from the oxidant gas supply port 113, and the cooling water in the oxidant-side porous gas flow path 5 evaporates. The power generation cell is cooled. Details of a method for supplying cooling water to the oxidant-side porous gas channel 5 will be described later.

  In the conventional fuel cell stack, the cooling cell is provided in order to limit the upper limit of the operating temperature of the fuel cell stack. However, in the fuel cell stack 100 of this embodiment, a cooling function is added to the oxidant side porous gas flow path. Thus, the cooling cell is omitted. As a result, the fuel cell stack can be made compact and the power generation efficiency per unit volume can be improved.

  Next, a method for supplying cooling water to the oxidant-side porous gas channel 5 of this embodiment will be described.

  The following points are important in order to uniformly supply the oxidizing gas and the cooling water to the power generation surface of each unit power generation cell with respect to the oxidizing agent side porous gas flow path 5. First, in the porous gas channel, the pores of the porous body become the channel, so that the oxidant gas and water flow in a very narrow space compared to the channel groove formed by conventional press processing or the like. Become. Therefore, if the oxidant gas and the cooling water are supplied from the same location in the porous gas flow path, it is difficult to stably supply both the oxidant gas and the cooling water. For example, only the cooling water is supplied. It tends to occur that the oxidant gas is not supplied, and conversely, only the oxidant gas is supplied. Such a phenomenon varies depending on the position of the porous gas flow path, and the state changes with time. Therefore, it is difficult to control the supply of the oxidant gas and water to the porous gas flow path. As a result, not only the supply amount varies within the power generation plane of the unit power generation cell, but also the supply amount variation occurs in each unit power generation cell. For this reason, it is important to supply the oxidant gas and the cooling water from different locations in the porous gas channel so that the supply of the oxidant gas and the cooling water to the porous gas channel do not interfere with each other. is there.

FIG. 2 shows the configuration of the separator used in the fuel cell stack of this example. 2A is a plan view of the separator as viewed from the cathode side, FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG. 2A, and FIG. 2C is a perspective view of the separator as viewed from the anode side. A plan view is shown. The separator has a configuration in which the fuel side porous gas channel 4 is disposed on one surface of the metal plate 3 and the oxidant side porous gas channel 5 is disposed on the other surface. The separator includes a fuel supply manifold 11, a fuel discharge manifold 12, an oxidant supply manifold 13, an oxidant discharge manifold 14, and a cooling water supply manifold 15 as internal manifolds. The cooling water supply manifold 15 is formed between the oxidant supply manifold 13 and the power generation surface. As shown in FIG. 2B, the boundary 16 between the oxidant supply manifold 13 and the cooling water supply manifold 15 is provided with a boundary seal 7 to prevent air and cooling water from entering. Yes.
Thus, the oxidant gas and the cooling water supplied from the oxidant supply manifold 13 and the cooling water supply manifold 15 are configured not to interfere with each other with respect to the oxidant side porous gas flow path 5.

  Further, the separator is provided with a seal member 6 to prevent leakage of the reaction gas on the cathode side and the anode side. On the cathode side, the oxidant and the cooling water are supplied from the oxidant supply manifold 13 and the cooling water supply manifold 15 to the oxidant side porous gas flow path 5, and the exhaust gas that has not been used for power generation and the cooling water that has not evaporated. A portion is discharged from the oxidant discharge manifold 14 to the outside of the stack. On the other hand, on the anode side, fuel is supplied from the fuel supply manifold 11 to the fuel-side porous gas flow path 4, and fuel that has not been used for power generation is discharged from the fuel discharge manifold 12 to the outside of the stack.

  The flow of oxidant gas and cooling water in the fuel cell stack of this embodiment will be described with reference to FIGS. FIG. 3 is an exploded perspective view of the power generation cell when stacked using the separator shown in FIG. 2. 4 is a cross-sectional view of the vicinity of the oxidizing agent supply manifold 13 and the cooling water manifold of the power generation cell in the AA ′ cross section of FIG.

  As shown in FIG. 3, an oxidant side porous gas flow path 5 and a fuel side porous gas flow path 4 are arranged at predetermined positions of a metal plate 3 on which each manifold is formed to constitute a separator. In the separator of the present embodiment, the oxidant-side porous gas channel 5 is disposed so as to cover the cooling water supply manifold 15 of the metal plate 3, and an opening is provided at a location corresponding to the cooling water supply manifold 15 of the metal plate 3. Have. A manifold is also formed at a position corresponding to the separator in the membrane electrode assembly 1 including the gas diffusion layer 2, and the membrane electrode assembly 1 is laminated on both surfaces of the separator via the seal member 6.

  As shown in FIG. 4, the oxidant side porous gas flow path 5 is arranged on the metal plate 3 so as to cover a part of the opening of the cooling water supply manifold 15. At this time, the oxidant-side porous gas flow path 5 is arranged so that an opening through which the cooling water supply manifold 15 can communicate in the stack 100 exists. With this configuration, the porous body constituting the oxidant-side porous gas channel 5 protrudes into the cooling water manifold. A narrowed portion is formed in the cooling water manifold by protruding the porous body.

  Further, a boundary seal 7 is provided at a boundary portion 16 between the oxidant supply manifold 13 and the cooling water supply manifold 15 in order to prevent air and cooling water from being mixed. The boundary seal 7 is obtained by impregnating the pores of the oxidant-side porous gas flow channel 5 located at the boundary 16 of the portion covering the cooling water supply manifold 15 with silicon rubber or fluorine rubber. be able to. Further, the water-absorbing polymer may be impregnated. In this case, the water-absorbing polymer is expanded by the water flowing through the cooling water supply manifold 15 and functions as the boundary seal 7 while the water is flowing. Furthermore, the water absorbed by the water-absorbing polymer evaporates to the oxidant supply manifold 13 side, thereby functioning as humidification of the oxidant gas and having a self-humidification function. Further, the boundary seal 7 needs to be formed also on the fuel gas flow path side of the metal plate 3. The boundary seal 7 located on the fuel gas flow path side may form a seal on the metal plate 3, or the oxidant side porous gas flow path 5 impregnated with a sealing material or a water-absorbing polymer may be a boundary portion 16. It is good also as a boundary seal 7 by bending by. Further, in this embodiment, an example is shown in which an opening is provided in the oxidant side porous gas flow path 5 so as to cover the boundary part 16, but the oxidant side porous gas flow path is provided in the boundary part 16. It is also possible to provide the boundary seal 7 by providing seal members on both the oxidant side and the fuel side of the boundary portion 16 without arranging 5.

Thus, in this embodiment, since the boundary seal 7 is provided at the boundary portion 16 between the oxidant supply manifold 13 and the cooling water supply manifold 15, the oxidant gas and the oxidant side porous gas channel 5 Cooling water is supplied without interfering with each other. Specifically, the oxidant gas supply path and the cooling water supply path indicated by the arrows in FIGS. 3 and 4 are supplied. The cooling water flowing through the cooling water supply manifold 15 may flow into the oxidant-side porous gas flow path 5 of each unit power generation cell due to the capillary force of the porous body constituting the constriction and the supply pressure of the cooling medium. it can. In this way, the cooling water flows into the oxidant side porous gas flow path 5, whereby the cooling water is supplied to the central region of the oxidant side porous gas flow path 5. On the other hand, the oxidant supply manifold 13 is disposed so as to cover the periphery of the cooling water supply manifold 15 and is configured to be in contact with the oxidant side porous gas flow path 5 around the cooling water supply manifold 15. The oxidant gas passes through the oxidant supply manifold 13 and is supplied to the oxidant side porous gas channel 5 from both sides of the outer periphery of the cooling water supply manifold 15. The cooling water supplied to the oxidant side porous gas flow path 5 is diffused to the power generation surface by the flow of the oxidant gas supplied from the outer periphery thereof. The cooling water diffused in the power generation surface evaporates due to the heat generated by the power generation reaction, so that the temperature in the cell can be kept constant.
The evaporated gas is discharged from the oxidant discharge manifold 14 to the outside of the stack through the discharge system piping.

  FIG. 5 is a schematic diagram showing an oxidant and cooling water supply / discharge system of the fuel cell system of this embodiment. As an example, the fuel gas is described as hydrogen and the oxidant gas is air. However, the fuel gas can be any gas that is rich in hydrogen, and the oxygen gas is best if it is oxygen.

  The gas supply system to the fuel cell stack 100 is composed of an oxidant gas blower 52 that supplies oxidant air and a piping system that connects the oxidant gas supply port 113, and unreacted gas, water vapor, and condensed from the oxidant gas discharge port 114. It consists of a piping system that discharges generated water and cooling water that has not been evaporated. The cooling water supply system is supplied from the cooling water supply pump 51 through a pipe connecting the cooling water supply port 117 of the stack 100 and supplied from the cooling water supply manifold 15 inside the stack 100 to the oxidant gas flow path of each unit power generation cell. Is done. Although the fuel system is not shown, the supply is performed by the pressure of a blower or a hydrogen cylinder.

  Although the cooling water can be supplied from the outside, the water in the oxidant exhaust gas is condensed by the heat exchanger 53, and the water collected in the water recovery tank 54 is reused to be generated by the power generation reaction. Water can be used effectively, and the system can be made compact.

(Example 2)
In this example, a modification of the separator used in the fuel cell stack of Example 1 will be described.
The configuration other than the separator is the same as that of the first embodiment.

  FIG. 5 shows a plan view of the metal plate as viewed from the cathode side in this embodiment. In this embodiment, a plurality of cooling water supply manifolds 15 are provided between the oxidant supply manifold 13 and the oxidant side porous gas flow path. An oxidant-side porous gas channel 5 and a fuel-side porous gas channel 4 are arranged on the metal plate 3 to form a separator. At this time, similarly to the first embodiment, it is preferable to seal the boundary portion between the oxidant supply manifold 13 and the coolant supply manifold 15 so that the oxidant gas and the coolant are not mixed.

  According to the configuration of the present embodiment, since the oxidant gas can flow between the cooling water supply manifolds 15 divided into a plurality of parts, there is an advantage that the cooling medium is more easily diffused in the power generation surface. Moreover, since the location which supplies oxidizing gas with respect to a porous gas flow path disperse | distributes, it has the advantage that it becomes easy to supply oxidizing gas to the whole electric power generation surface.

(Example 3)
In this embodiment, an example applied to an alkaline fuel cell will be described. The alkaline fuel cell is a fuel cell using an anion exchange electrolyte membrane represented by an amine group, and is characterized in that an anion exchange electrolyte membrane is used as the electrolyte membrane of the fuel cell of Example 1.

  Alkaline fuel cells have the advantage that no precious metal may be used as a catalyst, and liquid fuels containing alcohol such as methanol and ethanol can be used as fuel. A gas containing oxygen such as air can be used as the oxidizing agent. For example, the cell reaction of an alkaline fuel cell when methanol is used as the fuel is as follows.

(Chemical formula 1)
Anode: CH ₃ OH + 6OH ⁻ ⇒ CO ₂ + 5H ₂ O + 6e ⁻
Cathode: 3 / 2O ₂ + 3H ₂ O + 6e ⁻ → 6OH ⁻
Overall: CH ₃ OH + 3 / 2O ₂ ⇒ CO ₂ + 2H ₂ O

The air supplied to the cathode side becomes OH ^- ions by reaction with water at the electrode. OH ^- ions move through the electrolyte and combine with hydrogen on the anode side to form water. Thus, in an alkaline fuel cell, water is required for power generation on the cathode side.

  By adopting a system that supplies oxidant gas and cooling water to the oxidant side porous gas flow path of the alkaline fuel cell, the fuel cell is cooled and the water necessary for power generation is continuously supplied on the cathode side. Therefore, it is possible to provide an alkaline fuel cell capable of stable power generation.

DESCRIPTION OF SYMBOLS 1 Membrane electrode assembly 2 Gas diffusion layer 3 Metal plate 4 Fuel side porous gas flow path 5 Oxidant side porous gas flow path 6 Seal member 7 Manifold boundary seal part 11 Fuel supply manifold 12 Fuel discharge manifold 13 Oxidant supply manifold 14 Oxidant discharge manifold 15 Cooling water supply manifold 16 Manifold boundary 51 Cooling water supply pump 52 Oxidizing gas blower 53 Heat exchanger 54 Water recovery tank 55 Cooling water path 56 Oxidizing gas path 100 Fuel cell stack 105 Power generation unit 111 Fuel gas Supply port 112 Fuel gas discharge port 113 Oxidant gas supply port 114 Oxidant gas discharge port 115 Current collecting plate 116 Insulating plate 117 Cooling water supply port 118 End plate

Claims (9)

In the fuel cell separator in which the oxidant side porous gas channel is arranged on one side of the metal plate and the fuel side porous gas channel is arranged on the other side,
The metal plate includes an oxidant supply manifold for supplying oxidant gas to the oxidant side porous gas flow path, and a cooling water manifold for supplying cooling water to the oxidant side porous gas flow path. ,
The cooling water manifold is provided between the oxidant supply manifold and the oxidant side porous gas flow path;
A fuel cell separator comprising a seal member for preventing mixing of oxidant gas and cooling water at a boundary portion between the oxidant supply manifold and the cooling water manifold.   2. The fuel cell separator according to claim 1, wherein a porous body constituting the oxidant-side porous gas flow path protrudes inside the cooling water manifold.   2. The fuel cell separator according to claim 1, wherein the sealing member has a structure in which a porous body is impregnated with a water-absorbing polymer.   2. The fuel cell separator according to claim 1, wherein the cooling water manifold is divided into a plurality of parts. A fuel comprising a stack in which a fuel cell separator in which an oxidant-side porous gas channel is disposed on one surface of a metal plate and a fuel-side porous gas channel on the other surface and membrane electrode assemblies are alternately stacked In batteries,
The metal plate includes an oxidant supply manifold for supplying oxidant gas to the oxidant side porous gas flow path, and a cooling water manifold for supplying cooling water to the oxidant side porous gas flow path. ,
The cooling water manifold is provided between the oxidant supply manifold and the oxidant side porous gas flow path;
A fuel cell comprising a seal member for preventing mixing of oxidant gas and cooling water at a boundary portion between the oxidant supply manifold and the cooling water manifold.   6. The fuel cell according to claim 5, wherein a porous body that constitutes the oxidant-side porous gas channel protrudes inside the cooling water manifold.   6. The fuel cell according to claim 5, wherein the seal member has a porous body impregnated with a water-absorbing polymer.   6. The fuel cell according to claim 5, wherein the cooling water manifold is divided into a plurality of parts.   6. The fuel cell according to claim 5, wherein the electrolyte membrane of the membrane electrode assembly is an anion exchange type electrolyte membrane.