JP5339261B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen. More specifically, the present invention relates to a technique for improving gas diffusion performance of a gas diffusion layer constituting a fuel cell.

  In recent years, fuel cells that have high energy conversion efficiency and do not generate harmful substances due to power generation reactions have attracted attention. As one of such fuel cells, a polymer electrolyte fuel cell that operates at a low temperature of 100 ° C. or lower is known.

  A polymer electrolyte fuel cell has a basic structure in which a polymer electrolyte membrane, which is an electrolyte membrane, is disposed between a fuel electrode and an air electrode. The fuel electrode contains hydrogen and the air electrode contains oxygen. It is a device that supplies the agent gas and generates power by the following electrochemical reaction.

Fuel electrode: H ₂ → 2H ++ 2e ⁻ (1)
Air electrode: 1 / 2O ₂ + 2H ++ 2e ⁻ → H ₂ O (2)
The fuel electrode and the air electrode have a structure in which a catalyst layer and a gas diffusion layer are laminated. The catalyst layers of the electrodes are arranged opposite to each other with the solid polymer film interposed therebetween, thereby constituting a fuel cell. The catalyst layer is a layer formed by binding carbon particles carrying a catalyst with an ion exchange resin. The gas diffusion layer becomes a passage for the oxidant gas and the fuel gas.

  At the fuel electrode, hydrogen contained in the supplied fuel is decomposed into hydrogen ions and electrons as shown in the above formula (1). Among these, hydrogen ions move inside the solid polymer electrolyte membrane toward the air electrode, and electrons move to the air electrode through an external circuit. On the other hand, in the air electrode, oxygen contained in the oxidant gas supplied to the air electrode reacts with hydrogen ions and electrons that have moved from the fuel electrode, and water is generated as shown in the above formula (2). In this way, in the external circuit, electrons move from the fuel electrode toward the air electrode, so that electric power is taken out.

The gas diffusion layer has been developed to improve gas diffusibility. For example, Patent Document 1 discloses that a fluid (gas diffusion paste) containing a conductive substance is applied to the surface of a base sheet (carbon base material) obtained by impregnating a water-repellent material in a void inside a papermaking sheet. Disclosed is a gas diffusion member in which a multilayer structure in which a dense layer is laminated on the surface of a coarse layer is formed.
JP 2005-71941 A

  Conventionally, in a gas diffusion layer used in a fuel cell, the gas diffusion paste is applied to a carbon base material having a single structure. Therefore, the application depth and distribution of the gas diffusion paste are likely to be uneven within the carbon base surface. There was a tendency to become. This is because the carbon base material having a single structure has a variation in the distribution of pores into which the gas diffusion paste can enter. As a result, the gas diffusibility of the gas diffusion layer becomes non-uniform in the plane, the electrochemical reaction is hindered depending on the location, and the operation stability of the fuel cell is impaired.

Furthermore, at the cathode, because the generated water was you move along the flow of the oxidizing agent, the upstream side as a gas diffusion layer of the oxidant stream is likely to dry, the gas diffusion layer toward the downstream side of the flow of oxidant is over-humidification There was a problem that would be in a state.

  The present invention has been made in view of these problems, and an object thereof is to provide a technique for improving the gas diffusibility of a gas diffusion layer having a multilayer structure. Another object of the present invention is to provide a technique for making the water distribution in the gas diffusion layer on the cathode side uniform.

One embodiment of the present invention is a fuel cell. The fuel cell includes an electrolyte membrane, an anode catalyst layer bonded to one surface of the electrolyte membrane, an anode gas diffusion layer disposed on the outer surface of the anode catalyst layer, and a fuel along the surface of the anode gas diffusion layer. , A cathode catalyst layer bonded to the other surface of the electrolyte membrane, a cathode gas diffusion layer disposed on the outer surface of the cathode catalyst layer, and an oxidizer along the surface of the cathode gas diffusion layer An anode gas diffusion layer having a multilayer structure including a first base material layer and a second base material layer, and an average pore diameter of the first base material layer There are formed in the kneaded product of the second and larger anode substrate than the average pore size of the base layer, the first applied to the substrate layer conductivity of the anode gas diffusion layer powder and water repellent, the anode gas Ano having a thickness equal to a thickness of the first base layer of the diffusion layer Has a de microporous layer, a cathode gas diffusion layer is a multilayer structure comprising a first substrate layer and the second base material layer, the average pore diameter of the first base layer is first The cathode gas diffusion layer is formed of a cathode base material having a larger average pore diameter than the base material layer 2 and a kneaded mixture of conductive powder and water repellent applied to the first base material layer of the cathode gas diffusion layer. first possess the cathode microporous layer, a having a thickness equal to a thickness of the substrate layer, and the anode catalyst layer and the anode microporous layer of the anode gas diffusion layer, cathode catalyst layer and the cathode gas diffusion layer cathode microporous layer and is laminated so that to contact respectively in the anode gas diffusion layer and a cathode gas diffusion layer, respectively, an average pore diameter of the second base layer is 10 to 100 [mu] m, a first group of As long as the average pore diameter of the material layer does not exceed 200 μm, the flatness of the second base material layer Characterized in der Rukoto more than twice the HitoshiHoso pore size.

According to this aspect, in the gas diffusion layers of the anode and the cathode, the thickness of the microporous layer made of the kneaded mixture of the conductive powder and the water repellent is the portion where the pore diameter in the cathode base material is relatively large . 1 substrate layer . As a result, variations in the thickness and distribution of the microporous layer are suppressed, and the operational stability of the fuel cell is improved.

The first base material layer of the cathode gas diffusion layer may have higher water repellency than the second base material layer of the cathode gas diffusion layer .

  According to this aspect, in the gas diffusion layer of the cathode, the water repellency of the microporous layer on the upstream side of the oxidant flow becomes higher. As a result, the microporous layer on the upstream side of the oxidant flow is further suppressed from drying, and the microporous layer on the downstream side of the oxidant flow is further suppressed from being excessively humidified.

In the above aspect, the thickness of the first base material layer of the cathode gas diffusion layer may be thicker on the upstream side of the oxidant flow than on the downstream side of the oxidant flow.

  According to this aspect, in the gas diffusion layer of the cathode, the water repellency of the microporous layer on the upstream side of the oxidant flow is increased. In other words, the water permeability of the microporous layer upstream of the oxidant flow is reduced. As a result, drying of the microporous layer on the upstream side of the oxidant flow is suppressed, and the microporous layer on the downstream side of the oxidant flow is suppressed from being excessively humidified. As a result, the moisture in the gas diffusion layer and the electrolyte membrane is appropriately maintained, and the operation stability of the fuel cell is improved.

  According to the present invention, the gas diffusibility of the gas diffusion layer can be improved.

(Embodiment 1)
FIG. 1 is a perspective view schematically showing the structure of an electrode catalyst according to Embodiment 1 and a fuel cell 10 using the electrode catalyst. FIG. 2 is a cross-sectional view taken along the line AA of FIG. The fuel cell 10 includes a flat cell 50, and a separator 34 and a separator 36 are provided on both sides of the cell 50. Although only one cell 50 is shown in this example, the fuel cell 10 may be configured by stacking a plurality of cells 50 via the separator 34 or the separator 36. The cell 50 includes a solid polymer electrolyte membrane 20, a fuel electrode (anode) 22, and an air electrode (cathode) 24. The fuel electrode 22 has a laminate composed of a catalyst layer 26 and a gas diffusion layer 28. Similarly, the air electrode 24 has a laminate composed of the catalyst layer 30 and the gas diffusion layer 32. The catalyst layer 26 of the fuel electrode 22 and the catalyst layer 30 of the air electrode 24 are provided so as to face each other with the solid polymer electrolyte membrane 20 interposed therebetween.

  A gas flow path 38 is provided in the separator 34 provided on the fuel electrode 22 side, and fuel gas is supplied to the cell 50 through the gas flow path 38. Similarly, a gas flow path 40 is also provided in the separator 36 provided on the air electrode 24 side, and an oxidant gas is supplied to the cell 50 through the gas flow path 40. Specifically, during operation of the fuel cell 10, fuel gas, for example hydrogen gas, flows from the upper side to the lower side along the surface of the gas diffusion layer 28 in the gas flow path 38, so that the fuel gas is supplied to the fuel electrode 22. Supplied. On the other hand, during operation of the fuel cell 10, an oxidant gas, for example, air flows in the gas flow path 40 from the upper side to the lower side along the surface of the gas diffusion layer 32, thereby supplying the oxidant gas to the air electrode 24. Is done. Thereby, a reaction occurs in the cell 50. When hydrogen gas is supplied to the catalyst layer 26 via the gas diffusion layer 28, hydrogen in the gas becomes protons, and these protons move through the solid polymer electrolyte membrane 20 toward the air electrode 24. At this time, the emitted electrons move to the external circuit and flow into the air electrode 24 from the external circuit. On the other hand, when air is supplied to the catalyst layer 30 through the gas diffusion layer 32, oxygen is combined with protons to become water. As a result, electrons flow from the fuel electrode 22 toward the air electrode 24 in the external circuit, and electric power can be taken out.

  The solid polymer electrolyte membrane 20 exhibits good ion conductivity in a wet state, and functions as an ion exchange membrane that moves protons between the fuel electrode 22 and the air electrode 24. The solid polymer electrolyte membrane 20 is formed of a solid polymer material such as a fluorine-containing polymer or a non-fluorine polymer. A fluorocarbon polymer or the like can be used. Examples of the sulfonic acid type perfluorocarbon polymer include Nafion (manufactured by DuPont: registered trademark) 112. Examples of non-fluorine polymers include sulfonated aromatic polyetheretherketone and polysulfone.

  The catalyst layer 26 constituting the fuel electrode 22 is composed of an ion exchange resin and carbon particles carrying a catalyst, that is, catalyst-carrying carbon particles. The ion exchange resin has a role of transmitting protons between the carbon particles carrying the catalyst and the solid polymer electrolyte membrane 20 connected to each other. The ion exchange resin may be formed of the same polymer material as the solid polymer electrolyte membrane 20. Examples of the supported catalyst include those obtained by alloying one or two of platinum, ruthenium, rhodium and the like. Examples of the carbon particles supporting the catalyst include acetylene black, ketjen black, and carbon nanotube.

  The gas diffusion layer 28 constituting the fuel electrode 22 has an anode substrate 60 and a microporous layer 62 applied to the anode substrate 60. A method for manufacturing the gas diffusion layer 28 will be described later.

  The anode substrate 60 has a first substrate layer 64 and a second substrate layer 66. The first base material layer 64 and the second base material layer 66 are preferably composed of a porous body having electron conductivity. For example, carbon paper, carbon woven fabric, or non-woven fabric can be used. The 1st base material layer 64 is a part which is located in the solid polymer electrolyte membrane 20 side, and an average pore diameter is comparatively large. The second base material layer 66 is located on the opposite side of the solid polymer electrolyte membrane 20 and has a relatively small average pore diameter.

The average pore diameter of the second base material layer 66 having a relatively small average pore diameter is preferably 10 to 100 μm . The average pore diameter of the flat HitoshiHoso pore size is relatively large first base layer 64 is more than twice is preferable average pore diameter of the second substrate layer 66. By making the average pore diameter of the first base material layer 64 more than twice the average pore diameter of the second base material layer 66, it is possible to make a clear difference in the permeability of the microporous layer 62, The effect of preventing the fine pore layer 62 from entering the second base material layer 66 is enhanced .

  The microporous layer 62 is a paste-like kneaded product obtained by kneading a conductive powder and a water repellent. For example, carbon black can be used as the conductive powder. As the water repellent, a fluorine resin such as tetrafluoroethylene resin (PTFE) can be used. It is preferable that the water repellent has a binding property. Here, the binding property refers to a property that can be made sticky (state) by joining things that are less sticky or those that tend to break apart. Since the water repellent has binding properties, a paste-like kneaded product can be obtained by kneading the conductive powder and the water repellent.

  The microporous layer 62 is applied to the first base material layer 64 having a relatively large pore diameter. For this reason, the microporous layer 62 is prescribed | regulated by the shape of the 1st base material layer 64, and variation in thickness and distribution has decreased. As a result, the gas diffusivity of the gas diffusion layer 28 is suppressed from varying depending on the location, and as a result, the operational stability of the fuel cell 10 subjected to the electrochemical reaction is improved.

  The catalyst layer 30 constituting the air electrode 24 is composed of an ion exchange resin and carbon particles carrying a catalyst, that is, catalyst-carrying carbon particles. The ion exchange resin has a role of transmitting protons between the carbon particles carrying the catalyst and the solid polymer electrolyte membrane 20 connected to each other. The ion exchange resin may be formed of the same polymer material as the solid polymer electrolyte membrane 20. Examples of the supported catalyst include those obtained by alloying one or two of platinum, ruthenium, rhodium and the like. Examples of the carbon particles supporting the catalyst include acetylene black, ketjen black, and carbon nanotube.

  The gas diffusion layer 32 constituting the air electrode 24 has a cathode base material 70 and a microporous layer 72 applied to the cathode base material 70. A method for manufacturing the gas diffusion layer 32 will be described later.

  The cathode base material 70 has a first base material layer 74 and a second base material layer 76. The first base material layer 74 and the second base material layer 76 are preferably composed of a porous body having electron conductivity, and for example, carbon paper, carbon woven fabric or non-woven fabric can be used. The 1st base material layer 74 is located in the solid polymer electrolyte membrane 20 side, and is a part with a comparatively large pore diameter. The second base material layer 76 is located on the opposite side of the solid polymer electrolyte membrane 20 and has a relatively small pore diameter.

The average pore diameter of the second base material layer 76 having a relatively small average pore diameter is preferably 10 to 100 μm . The average pore diameter of the flat HitoshiHoso pore size is relatively large first base material layer 74 is more than twice is preferable average pore diameter of the second substrate layer 76. By making the average pore diameter of the first base material layer 74 at least twice the average pore diameter of the second base material layer 76, it is possible to make a clear difference in the permeability of the microporous layer 72, The effect of preventing the fine pore layer 72 from entering the second base material layer 76 is enhanced .

  The microporous layer 72 is a paste-like kneaded product obtained by kneading a conductive powder and a water repellent. For example, carbon black can be used as the conductive powder. In addition, as the water repellent, a fluorine resin such as tetrafluoroethylene resin (PTFE) can be used. It is preferable that the water repellent has a binding property. Here, the binding property refers to a property that can be made sticky (state) by joining things that are less sticky or those that tend to break apart. Since the water repellent has binding properties, a paste-like kneaded product can be obtained by kneading the conductive powder and the water repellent.

  The microporous layer 72 is applied to the first base material layer 74 having a relatively large pore diameter. For this reason, the microporous layer 72 is prescribed | regulated by the shape of the 1st base material layer 74, and variation in thickness and distribution has decreased. As a result, the gas diffusibility of the gas diffusion layer 32 is suppressed from varying depending on the location, and as a result, the operational stability of the fuel cell 10 subjected to the electrochemical reaction is improved.

(Production method of gas diffusion layer)
The gas diffusion layer 28 constituting the fuel electrode 22 and the gas diffusion layer 32 constituting the air electrode 24 shown in FIGS. 1 and 2 can be produced by the following procedure. Since the gas diffusion layer 28 and the gas diffusion layer 32 can be manufactured in the same procedure, the manufacturing procedure of the gas diffusion layer 32 will be mainly described, and the manufacturing procedure of the gas diffusion layer 28 will be described as necessary.

  First, a cathode substrate 70 having a first substrate layer 74 and a second substrate layer 76 made of carbon paper as shown in FIG. 3 is prepared. Although the thickness of the 1st base material layer 74 is not specifically limited, For example, it can be 50 micrometers. The thickness of the second base material layer 76 is not particularly limited, but can be set to 150 μm, for example.

  Next, the cathode base material 70 is immersed in the FEP dispersion so that the weight ratio of carbon paper: FEP (tetrafluoroethylene-hexafluoropropylene copolymer) = 95: 5, and then maintained at 380 ° C. for 2 hours. Then, heat treatment (FEP water repellent treatment) is performed. By immersing the cathode base material 70 in the FEP dispersion liquid, the first base material layer 74 is more impregnated with the FEP dispersion liquid than the second base material layer 76. Thereby, the water repellency after the heat treatment is higher in the first base material layer 74 than in the second base material layer 76. In other words, the first base material layer 74 has lower water permeability than the second base material layer 76.

  In addition, about the anode base material 60, the anode base material 60 is immersed in a FEP dispersion so that it may become carbon paper: FEP = 60: 40.

  Next, carbon black and terpineol as a solvent and triton of a nonionic surfactant are mixed at a room temperature with a universal mixer for 60 minutes so that the weight ratio is carbon black: terpineol: triton = 20: 150: 3. Then, the mixture is mixed uniformly to produce a carbon paste.

  Next, the carbon paste and the fluororesin are kneaded. Specifically, the carbon paste is put into a hybrid mixer container and cooled until the carbon paste reaches 10 to 12 ° C. A fluororesin dispersion containing a fluororesin as a water repellent is introduced into the cooled carbon paste so that the weight ratio is carbon paste: fluororesin (a fluororesin component contained in the dispersion) = 31: 1. As the fluororesin dispersion, a dispersion in which the weight ratio of the fluororesin in the dispersion is low molecular PTFE: polymer PTFE = 20: 3 can be used.

  Subsequently, the mixture of the carbon paste and the fluororesin is mixed for 12 to 18 minutes in the mixing mode of the hybrid mixer (manufactured by Keyence Corporation: EC500), and then defoamed in the defoaming mode for 1 to 3 minutes. A gas diffusion layer paste for the cathode for forming the microporous layer 62 is obtained by naturally cooling the paste after defoaming.

  In the case of the gas diffusion layer paste for the anode, the above-mentioned garbon paste and low molecular PTFE are put into a hybrid mixer container so that the weight ratio is carbon paste: low molecular PTFE = 26: 3, Mix for 15 minutes in the mixing mode of the hybrid mixer. After mixing, the hybrid mixer is switched to defoaming mode and defoamed for 4 minutes. When the supernatant liquid accumulates on the upper part of the paste after defoaming, the supernatant liquid is discarded and the paste is naturally cooled to obtain a gas diffusion layer paste for the anode.

The cathode gas diffusion layer paste is applied to the first substrate layer 74 of the cathode substrate 70. In the present embodiment, since the first base material layer 74 has a larger pore diameter than the second base material layer 76, the region where the gas diffusion layer paste is applied is limited to the first base material layer 74. The coating thickness of the gas diffusion layer paste can be controlled. For this reason, by smoothing the interface between the first base material layer 74 and the second base material layer 76, variation in the coating thickness and distribution of the gas diffusion layer paste, that is, the microporous layer 72 is reduced. It becomes possible.

  The cathode base material 70 coated with the gas diffusion layer paste is dried at 60 ° C. for 60 minutes using a hot air dryer or the like, and then heat treated at 360 ° C. for 2 hours, whereby the gas diffusion layer 32 constituting the air electrode 24 is formed. Is obtained.

(Embodiment 2)
Since the basic configuration of the fuel cell 10 of the second embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals as those of the first embodiment, and description thereof will be omitted as appropriate. In the first embodiment, the thickness of the first base material layer 74 of the cathode base material 70 is uniform. However, in the second embodiment, as shown in FIG. The base layer 74 is thicker on the upstream side of the oxidant flow than on the downstream side of the oxidant flow. For example, when the thickness of the entire cathode base material 70 is 200 μm, the thickness on the most upstream side (the uppermost part in FIG. 4) of the first base material layer 74 is 150 μm, and the first base material layer 74 is formed. The thickness of the most downstream side (lowermost part in FIG. 4) can be 20 μm.

  According to this, in the gas diffusion layer 32 of the cathode, the water repellency of the microporous layer 72 upstream of the oxidant flow is increased. In other words, the moisture permeability of the microporous layer 72 on the upstream side of the oxidant flow is lowered. As a result, drying of the microporous layer 72 on the upstream side of the oxidant flow is suppressed, and the microporous layer 72 on the downstream side of the oxidant flow is suppressed from being excessively humidified. As a result, the moisture of the gas diffusion layer 32 and the solid polymer electrolyte membrane 20 is kept moderate, and the operational stability of the fuel cell 10 is improved.

  In addition, by immersing the cathode base material 70 in the FEP dispersion, the first base material layer 74 is impregnated with the FEP dispersion more than the second base material layer 76. Thereby, the water repellency after the heat treatment is higher in the first base material layer 74 than in the second base material layer 76. In the present embodiment, since the ratio of the first base material layer 74 is higher on the upstream side of the oxidant flow, the microporous layer on the upstream side of the oxidant flow in the cathode gas diffusion layer 32. The water repellency of 72 becomes higher. As a result, the microporous layer 72 on the upstream side of the oxidant flow is further suppressed from drying, and the microporous layer 72 on the downstream side of the oxidant flow is further suppressed from being excessively humidified. .

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The form can also be included in the scope of the present invention.

  For example, in each of the above-described embodiments, the anode-side first base material layer 64 and the cathode-side first base material layer 74 are respectively the anode-side second base material layer 66 and the cathode-side base material. Although the pore diameter is larger than that of the second base material layer 76, the present invention is not limited to this. For example, the relationship between the first base layer 64 on the anode side and the second base layer 66 on the anode side, and the first base layer 74 on the cathode side and the second base layer 76 on the cathode side, The relationship may be as shown in the table below.

  The bulk density refers to the weight of the carbon fiber per unit volume. The basis weight is the weight of carbon fiber per unit area. Porosity refers to the ratio of pores per unit area.

  The bulk density and the basis weight are opposite to the pore size and the magnitude relationship. On the other hand, the porosity has the same magnitude relationship as the pore diameter, and it is also possible to define the first and second substrate layers of the anode and the cathode by the porosity instead of the pore diameter. .

  In the second embodiment, the thickness of the first base material layer 74 of the cathode base material 70 gradually decreases from the upstream side to the downstream side of the oxidant flow. However, the present invention is not limited to this. Absent. For example, as shown in FIG. 5, the thickness of the first base material layer 74 of the cathode base material 70 may be decreased stepwise.

  Further, the cathode gas flow path 40 may be bent in the middle. In this case, the cathode base is formed along the path of the gas flow path 40 from the upstream side to the downstream side of the oxidant flow. The thickness of the first base material layer 74 of the material 70 may be reduced.

1 is a perspective view schematically showing the structure of a fuel cell according to Embodiment 1. FIG. It is sectional drawing on the AA line of FIG. It is a figure which shows the structure of the cathode base material used for preparation of the gas diffusion layer for cathodes. 5 is a cross-sectional view showing a structure of a fuel cell according to Embodiment 2. FIG. It is sectional drawing which shows the structure of the fuel cell which concerns on a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell, 20 Solid polymer electrolyte membrane, 22 Fuel electrode, 24 Air electrode, 26, 30 Catalyst layer, 28, 32 Gas diffusion layer, 34, 36 Separator, 50 cell

Claims (3)

An electrolyte membrane;
An anode catalyst layer bonded to one surface of the electrolyte membrane;
An anode gas diffusion layer disposed on the outer surface of the anode catalyst layer;
Fuel supply means for supplying fuel along the surface of the anode gas diffusion layer;
A cathode catalyst layer bonded to the other surface of the electrolyte membrane;
A cathode gas diffusion layer disposed on an outer surface of the cathode catalyst layer;
An oxidant supply means for supplying an oxidant along the surface of the cathode gas diffusion layer;
With
The anode gas diffusion layer has a multilayer structure including a first base material layer and a second base material layer, and an average pore diameter of the first base material layer is an average of the second base material layer. An anode base material larger than the pore diameter, and a kneaded product of conductive powder and water repellent applied to the first base material layer of the anode gas diffusion layer; An anode microporous layer having a thickness equivalent to the thickness of the base material layer,
The cathode gas diffusion layer has a multilayer structure including a first base material layer and a second base material layer, and an average pore diameter of the first base material layer is an average of the second base material layer. A cathode base material having a pore diameter larger than the first base material layer of the cathode gas diffusion layer, and a kneaded product of a conductive powder and a water repellent agent. A cathode microporous layer having a thickness equivalent to the thickness of the substrate layer;
Have
The anode catalyst layer and the anode microporous layer of the anode gas diffusion layer are laminated so that the cathode catalyst layer and the cathode microporous layer of the cathode gas diffusion layer are in contact with each other,
In the anode gas diffusion layer and the cathode gas diffusion layer, respectively
The average pore diameter of the second base material layer is 10 to 100 μm, and the average pore diameter of the second base material layer is 2 within the range where the average pore diameter of the first base material layer does not exceed 200 μm. A fuel cell characterized by being more than doubled.   The fuel cell according to claim 1, wherein the first base material layer of the cathode gas diffusion layer has higher water repellency than the second base material layer of the cathode gas diffusion layer.   The thickness of the first base material layer of the cathode gas diffusion layer is such that the upstream side of the oxidant flow is thicker than the downstream side of the oxidant flow. 2. The fuel cell according to 2.

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