JP7359077B2 - Laminate for fuel cells - Google Patents

Description

The present invention relates to a cathode gas diffusion layer for a fuel cell.

Fuel cells are known that generate electricity by chemically reacting an anode gas such as hydrogen and a cathode gas such as oxygen.

In a fuel cell, an anode gas (fuel gas) such as hydrogen and a cathode gas (oxidant gas) such as oxygen are supplied to two electrically connected electrodes, and the fuel is electrochemically oxidized. This directly converts chemical energy into electrical energy.

At the anode (fuel electrode) to which hydrogen is supplied as anode gas, the reaction of formula (1) below proceeds.
H ₂ → 2H ⁺ + 2e ^- (1)

The electrons (e ⁻ ) generated in the above formula (1) pass through an external circuit, do work with an external load, and then reach the cathode (oxidizer electrode). On the other hand, the protons (H ⁺ ) generated in the above formula (1), while hydrated with water, move from the anode side to the cathode side within the electrolyte membrane sandwiched between the anode and the cathode by electroosmosis. do.

On the other hand, at the cathode, protons (H ⁺ ) generated by the above formula (1) that have passed through the electrolyte membrane, oxygen supplied as cathode gas, and electrons (e) generated by the above formula (1) via an external circuit. ^- ) causes the reaction of the following formula (2) to proceed.
2H ⁺ + 1/2O ₂ + 2e ^- → H ₂ O ... (2)

Therefore, the chemical reaction shown in formula (3) below proceeds in the entire battery, generating an electromotive force and performing electrical work on the external load.
H ₂ + 1/2O ₂ → H ₂ O...(3)

Such fuel cells are usually constructed by stacking a plurality of single cells each having a basic structure of a membrane electrode assembly in which an electrolyte membrane is sandwiched between a pair of electrodes. Among these, solid polymer electrolyte fuel cells that use solid polymer electrolyte membranes as electrolyte membranes have advantages such as being easy to downsize and operating at low temperatures, so they are particularly popular in mobile devices and other devices. It is expected to be used as a power source for mobile devices such as portable devices and electric vehicles.

Here, the configuration of a single cell of a solid polymer electrolyte fuel cell includes, for example, an anode-side separator, an anode-side gas diffusion layer, an anode-side catalyst layer, an electrolyte membrane, a cathode-side catalyst layer, a cathode-side gas diffusion layer, and A laminate in which cathode-side separators are stacked in this order is known.

The gas diffusion layer is a laminate in which a microporous layer (MPL) is laminated on the surface of a conductive porous diffusion layer base material layer such as carbon paper or carbon cloth. The microporous layer (MPL) is formed by applying a material paste to the surface of the diffusion layer base layer. The gas diffusion layer in which MPL is formed has excellent gas diffusion properties.

In such fuel cells, hydrogen peroxide may be generated during the reaction process. The generated hydrogen peroxide then decomposes the ionomer, which is an electrolyte component. As a result, the electrolyte membrane containing the ionomer as a main component and the catalyst layer containing the ionomer as a component deteriorate, causing problems in battery durability.

On the other hand, it is known to add a cerium-containing oxide to the material of the laminate that constitutes the fuel cell. The cerium-containing oxide generates cerium ions that function as a catalyst for decomposing hydrogen peroxide.

However, the cerium-containing oxide is ionized in the acidic atmosphere within the electrode and slightly eluted from the containing layer. The eluted cerium ions are adsorbed to the sulfonic acid groups (-SO ₃ ^- ) in the ionomer contained in the electrolyte membrane and catalyst layer, and gradually inhibit proton conduction. For this reason, when the fuel cell is used for a long period of time, there is a risk that the power generation performance will deteriorate.

Therefore, in Patent Document 1, the water-repellent layer disposed in the gas diffusion layer is made of polytetrafluoroethylene (PTFE), which is a water-repellent member, and a cerium-containing oxide that generates cerium ions, which serve as a hydrogen peroxide decomposition catalyst. (CeO ₂ ), and it has been proposed that the mass ratio of the cerium-containing oxide to the water-repellent member be 5 to 20 mass%.

The technology described in Patent Document 1 suppresses contact of cerium-containing oxide (CeO ₂ ) with water and ionizes it by increasing the ratio of water-repellent material (PTFE) in the material constituting the water-repellent layer. Prevents elution. As a result, it is possible to suppress proton conduction inhibition caused by cerium ions.

JP2016-081630A

However, the present inventor has found that in the technique described in Patent Document 1, the gas diffusion layer at the cathode becomes hydrophilic due to cerium ions dissolved in the generated water, and the output performance may deteriorate due to flooding. Ta.

The present invention has been made in view of the above background, and uses cerium-containing oxide (CeO ₂ ) to at least partially decompose hydrogen peroxide produced during the reaction process of a fuel cell while converting it into produced water. Provided is a cathode-side gas diffusion layer for suppressing hydrophilization due to dissolved cerium ions and a decrease in output performance due to flooding caused by the hydrophilization, and as a result realizing a fuel cell with improved overall performance. The purpose is to

The output performance of a fuel cell is determined by resistance overvoltage, concentration overvoltage, and activation overvoltage, and the present inventors believe that by relatively reducing the content of cerium-containing oxide (CeO ₂ ), a slight resistance overvoltage can be achieved. Even when there is an increase, the concentration overvoltage can be significantly reduced, and as a result, the performance of the fuel cell as a whole can be improved, and the present invention has been completed. That is, the present invention is as follows.

A cathode side gas diffusion layer for a fuel cell,
The cathode side gas diffusion layer is a laminate in which a microporous layer is laminated on a diffusion layer base material layer,
The microporous layer includes carbon particles, polytetrafluoroethylene, and cerium oxide,
the mass ratio of the polytetrafluoroethylene to the cerium oxide is greater than 20;
Cathode side gas diffusion layer for fuel cells.

According to the cathode side gas diffusion layer for a fuel cell of the present invention, by using a relatively small amount of cerium-containing oxide (CeO ₂ ), hydrogen peroxide generated during the reaction process of the fuel cell is at least partially absorbed. While being decomposed, it is possible to suppress hydrophilization due to cerium ions dissolved in the produced water and a decrease in output performance due to flooding caused by this.

Therefore, according to the cathode-side gas diffusion layer for a fuel cell of the present invention, it is possible to realize a fuel cell in which deterioration is suppressed as a whole.

FIG. 1 is a cross-sectional view of a stack for a fuel cell according to one embodiment. FIG. 2 is a diagram showing the range of the present invention and the prior art regarding the mass ratio of polytetrafluoroethylene to cerium oxide. It is a graph showing the relationship between the mass ratio of polytetrafluoroethylene to cerium oxide in the cathode side microporous layer and output performance. It is a graph showing the relationship between the mass ratio of polytetrafluoroethylene to cerium oxide in the anode-side microporous layer and output performance.

Embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, but can be implemented with various modifications.

《Laminated body for fuel cells》
In explaining the cathode side gas diffusion layer for a fuel cell of the present invention, a stacked body constituting the fuel cell will be explained.

The structure of the laminate stored in a typical fuel cell includes, for example, an anode separator, an anode gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, a cathode gas diffusion layer, and a cathode gas diffusion layer. A laminate in which side separators are laminated in this order can be mentioned.

The cathode-side gas diffusion layer for a fuel cell of the present invention is arranged between a separator and a catalyst layer on the cathode side of a stack that constitutes a fuel cell.

FIG. 1 is a cross-sectional view of a laminate for a fuel cell according to one embodiment. The laminate 100 according to one embodiment includes an anode gas diffusion layer 10 in which an anode diffusion layer base material layer 11 and an anode microporous layer 12 are laminated, an anode catalyst layer 15, an electrolyte membrane 30, and a cathode catalyst layer. 25, and the cathode gas diffusion layer 20 in which the cathode diffusion layer base material layer 21 and the cathode microporous layer 22 are laminated in this order.

In the stacked body 100 shown in FIG. 1, a catalyst layer is present between the gas diffusion layer and the electrolyte membrane on each of the anode side and the cathode side. The microporous layer in the gas diffusion layer faces the catalyst layer on each of the anode side and the cathode side.

In the laminate 100 shown in FIG. 1, the cathode gas diffusion layer for a fuel cell of the present invention is a cathode gas diffusion layer 20 in which a cathode diffusion layer base material layer 21 and a cathode microporous layer 22 are laminated. becomes.

The cathode-side gas diffusion layer for a fuel cell of the present invention is produced during the reaction process of the fuel cell by setting the mass ratio of polytetrafluoroethylene to cerium oxide in a specific range in the microporous layer (MPL). A fuel that at least partially decomposes hydrogen peroxide while suppressing deterioration in output performance caused by hydrophilization due to cerium ions dissolved in produced water and flooding resulting from this, and as a result, improved overall performance. A battery can be realized.

<Gas diffusion layer>
The present invention relates to a gas diffusion layer on the cathode side. The gas diffusion layer has the function of diffusing and making the supplied reaction gas uniform, and spreading the gas to adjacent catalyst layers when used as a single cell of a fuel cell.

In the present invention, the gas diffusion layer is a laminate in which a microporous layer is laminated on a diffusion layer base material layer. Then, when incorporated into a fuel cell, the microporous layer is arranged so as to face the adjacent catalyst layer.

(Diffusion layer base material layer)
The diffusion layer base material layer in the gas diffusion layer is a porous layer that supplies a reactive gas to an adjacent catalyst layer when used as a single cell of a fuel cell. The diffusion layer base material layer is preferably made of a material that is gas permeable and electrically conductive.

In the present invention, any material that is commonly used for the diffusion layer base material layer can be used without particular limitation. For example, carbon porous bodies such as carbon paper or carbon cloth, or metal mesh or Examples include porous metal bodies such as foamed metal. Note that the carbon porous body such as carbon paper or carbon cloth may be made of, for example, carbon fibers and a binder such as a resin that is carbonized by firing.

In the present invention, the pore diameter, density, thickness, etc. of the diffusion layer base material layer constituting the gas diffusion layer are not particularly limited, and are appropriately set according to the required performance of the fuel cell to be formed. be able to.

(Microporous layer (MPL))
The microporous layer in the gas diffusion layer is a layer that exists on the diffusion layer base material layer and is adjacent to the catalyst layer in the case of a single cell of a fuel cell. By forming MPL in the gas diffusion layer constituting the stacked body for fuel cells, gas diffusivity in the fuel cell is improved.

The method for manufacturing the microporous layer (MPL) is not particularly limited, but for example, a slurry for forming the MPL is coated on the surface of the diffusion layer base layer using a die coater, or a paste for forming the MPL is applied. Examples include a method of applying by discharging from a coating head, followed by drying and baking.

The microporous layer in the gas diffusion layer of the present invention includes carbon particles, polytetrafluoroethylene which is a water-repellent resin, and cerium oxide (CeO ₂ ) which generates cerium ions that serve as a hydrogen peroxide decomposition catalyst. Therefore, the slurry for forming MPL or the paste for forming MPL is a composition containing these as essential components.

Examples of the carbon particles include particles of carbon black, graphene, graphite, and the like.

The average primary particle size of the carbon particles may be 25 nm to 70 nm. The average primary particle diameter of the carbon particles may be 25 nm or more, 45 nm or more, or 65 nm or more, and may be 70 nm or less, 60 nm or less, or 50 nm or less.

Note that the average primary particle diameter of carbon particles is calculated using an electron microscope such as a transmission electron microscope (TEM) or a scanning electron microscope (SEM). This value is the arithmetic average of the measured values obtained.

The cathode side gas diffusion layer for a fuel cell of the present invention includes cerium oxide and polytetrafluoroethylene as constituent materials in its microporous layer (MPL). The mass ratio of polytetrafluoroethylene to cerium oxide is greater than 20.

The mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer (MPL) on the cathode side may be 25 or more, or 30 or more, or 40 or less, or 35 or less.

If the mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer (MPL) on the cathode side is greater than 20, hydrogen peroxide produced during the reaction process of the fuel cell can be at least partially decomposed while being produced. It is possible to suppress deterioration in output performance due to hydrophilization due to cerium ions dissolved in water and flooding caused by the hydrophilization.

FIG. 2 is a diagram showing the range of the present invention and the range described in Patent Document 1, which is a prior art, regarding the mass ratio of polytetrafluoroethylene to cerium oxide.

Range A in FIG. 2 is the mass ratio of polytetrafluoroethylene to cerium oxide described in Patent Document 1. In the water-repellent layer described in Patent Document 1, the mass ratio of the cerium-containing oxide to the water-repellent member is 5 to 20% by mass. Therefore, the mass ratio of the water repellent member (polytetrafluoroethylene in the present application) to the cerium-containing oxide (cerium oxide in the present application) is 5 to 20 as shown in range A.

On the other hand, the cathode-side gas diffusion layer for a fuel cell according to the present invention has a mass ratio of polytetrafluoroethylene to cerium oxide of more than 20 in the microporous layer, and therefore falls within the range described in Patent Document 1. There are no duplicates.

Furthermore, for the microporous layer of the anode side gas diffusion layer used together with the cathode side gas diffusion layer for the fuel cell of the present invention, the mass ratio of polytetrafluoroethylene to cerium oxide is preferably 5.5 or more. preferable.

In the microporous layer of the gas diffusion layer on the anode side, when the mass ratio of polytetrafluoroethylene to cerium oxide is less than 5.5, water repellency is insufficient, and as a result, cerium ions dissolved in the generated water It may be difficult to suppress an increase in cell resistance of a fuel cell due to hydrophilization.

In the microporous layer of the gas diffusion layer on the anode side, the mass ratio of polytetrafluoroethylene to cerium oxide may be 6.0 or more, or 6.5 or more.

Further, in the microporous layer of the anode side gas diffusion layer, the mass ratio of polytetrafluoroethylene to cerium oxide is preferably less than 20.

In the cathode-side gas diffusion layer for a fuel cell according to the present invention, the mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer is greater than 20, but at the same time, the microporous layer of the anode-side gas diffusion layer When the ratio is 20 or more, hydrogen peroxide decomposition performance is insufficient, which may result in a large increase in resistance overvoltage.

In the microporous layer of the gas diffusion layer on the anode side, the mass ratio of polytetrafluoroethylene to cerium oxide may be 18 or less, or 16 or less.

In the present invention, the thickness of the microporous layer (MPL) constituting the gas diffusion layer is not particularly limited, and can be appropriately set depending on the required performance of the fuel cell to be formed. For example, it may be 20 μm or more.

<Other layers>
The cathode gas diffusion layer for a fuel cell of the present invention is one of the layers constituting a single cell of a solid polymer electrolyte fuel cell. In general, a laminate that becomes a single cell of a polymer electrolyte fuel cell consists of an anode separator, an anode gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, a cathode gas diffusion layer, and a cathode gas diffusion layer. The separators are stacked in this order.

(catalyst layer)
The catalyst layer that constitutes the fuel cell together with the cathode-side gas diffusion layer for the fuel cell of the present invention is not particularly limited, and any known catalyst layer may be used.

The anode side catalyst layer has a function of decomposing hydrogen (H ₂ ), which is a reactive gas, into protons (H ⁺ ) and electrons (e ⁻ ). On the other hand, the cathode side catalyst layer has a function of generating water (H ₂ O) from protons (H ⁺ ), electrons (e ⁻ ), and oxygen (O ₂ ).

The catalyst layers on the anode side and the cathode side can be formed of similar materials. For example, a conductive carrier supporting a catalyst such as platinum or a platinum alloy is used, and more specifically, a catalyst-supported carbon carrier in which a catalyst is supported on carbon particles such as carbon black that functions as a conductive substance is used. Examples include a layer composed of particles and an electrolyte component that exhibits proton conductivity through ion exchange groups, which is a component of the electrolyte membrane described above. The layer may be formed by coating catalyst-supported carbon particles with an electrolyte component such as an ionomer having proton conductivity.

The thickness of the catalyst layer constituting the fuel cell is not particularly limited, and can be appropriately set depending on the required performance of the fuel cell to be formed.

(electrolyte membrane)
The electrolyte membrane that constitutes the fuel cell together with the cathode gas diffusion layer for fuel cells of the present invention prevents the flow of electrons and gas, and also transfers protons (H ⁺ ) generated at the anode from the anode catalyst layer to the cathode side. It has the function of moving to the catalyst layer.

The electrolyte membrane is not particularly limited, and any membrane known as an electrolyte membrane used in fuel cells can be used. In the case of a solid polymer electrolyte fuel cell that uses a solid polymer electrolyte membrane as an electrolyte membrane, for example, an ion-conducting membrane made of a polymer electrolyte resin containing sulfonic acid groups such as perfluorosulfonic acid (PFSA) ionomer is used. Examples include ion-exchange membranes that have properties. Note that the membrane is not limited to sulfonic acid groups, and may be a membrane containing other ion exchange groups (electrolyte components), such as phosphoric acid groups or carboxylic acid groups.

A commercially available ion exchange membrane may be applied, and is made of a polymer electrolyte resin, which is a solid polymer material such as perfluorosulfonic acid (PFSA) ionomer, and has ion conductivity. It consists of an ion exchange membrane. Commercial products of fluororesin ion exchange membranes containing sulfonic acid groups include, for example, DuPont's Nafion (registered trademark), Asahi Kasei Corporation's Aciplex (registered trademark), and Asahi Glass Co., Ltd.'s Flemion (registered trademark). etc.

The thickness of the electrolyte membrane constituting the fuel cell is not particularly limited, and can be appropriately set depending on the required performance of the fuel cell to be formed. The thickness of the electrolyte membrane may be, for example, 10 μm or less.

Hereinafter, the present invention will be explained in more detail by showing experimental results.

<Experimental Example 1> Relationship between the mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer on the cathode side and output performance In Experimental Example 1, the mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer on the cathode side was Six fuel cells were fabricated by changing the mass ratio of . The output performance of the six obtained fuel cells was evaluated.

<Production of fuel cell>
(Preparation of cathode side gas diffusion layer)
A cathode side microporous layer (MPL) forming slurry containing carbon particles, polytetrafluoroethylene (PTFE), and cerium oxide (CeO ₂ ) was prepared. At this time, six types of slurries having different compositions were prepared so that the mass ratio of polytetrafluoroethylene to cerium oxide was different from each other.

Six sheets of carbon paper were prepared as porous substrates. The cathode side microporous layer (MPL) forming slurry prepared above is applied onto the surface of each carbon paper using a die coater, dried and then fired to form a microporous layer (MPL) on the porous base material layer. ) were laminated, and cathode side gas diffusion layers were prepared in which the mass ratios of polytetrafluoroethylene to cerium oxide in the microporous layers were different from each other.

(Preparation of anode side gas diffusion layer)
Six sheets of carbon paper were prepared as porous substrates. A slurry for forming a microporous layer (MPL) containing carbon particles, polytetrafluoroethylene (PTFE), and cerium oxide (CeO ₂ ) is prepared, coated on carbon paper using a die coater, dried, and then fired. In this way, six anode-side gas diffusion layers in which a microporous layer (MPL) was laminated on a porous base material layer were manufactured.

(Preparation of laminate)
Using the cathode gas diffusion layer and anode gas diffusion layer obtained above, an anode gas diffusion layer/anode catalyst layer/electrolyte membrane/cathode catalyst layer/cathode gas diffusion layer are laminated in this order. Six types of fuel cells were fabricated, each having a different mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer on the cathode side by constructing a stacked body and sandwiching it between a pair of separators.

Note that the anode-side catalyst layer and the cathode-side catalyst layer were arranged so that the microporous layer (MPL) of the adjacent gas diffusion layer faced each other.

<Evaluation of output performance>
The six types of fuel cells produced were evaluated for their output performance after a durability test. As part of the durability test, the temperature was repeatedly raised and lowered a number of times based on the number of years of use while sweeping the current at a constant low current density. After the durability test, the output at the maximum output point was evaluated when a reactive gas was flowed through the fuel cell and the current was swept.

The results obtained are shown in FIG. 3 as relative values based on the case where the mass ratio of polytetrafluoroethylene to cerium oxide in the cathode side microporous layer was 20.

FIG. 3 is a diagram showing the relationship between the mass ratio of polytetrafluoroethylene to cerium oxide in the cathode-side microporous layer and output performance. The horizontal axis of the graph is the mass ratio of polytetrafluoroethylene to cerium oxide in the cathode side microporous layer, and the vertical axis of the graph is the output performance (%) of the obtained fuel cell.

From FIG. 3, it can be seen that if the mass ratio of polytetrafluoroethylene to cerium oxide in the cathode side microporous layer is in a range exceeding 20, a fuel cell with high output performance can be obtained.

<<Experimental Example 2>> Relationship between the mass ratio of polytetrafluoroethylene to cerium oxide in the anode side microporous layer and output performance In Experimental Example 2, the mass ratio of polytetrafluoroethylene to cerium oxide in the anode side microporous layer was Six fuel cells were fabricated by changing the mass ratio of . The output performance of the six obtained fuel cells was evaluated.

<Production of fuel cell>
(Preparation of anode side gas diffusion layer)
A slurry for forming an anode side microporous layer (MPL) containing carbon particles, polytetrafluoroethylene (PTFE), and cerium oxide (CeO ₂ ) was prepared. At this time, six types of slurries having different compositions were prepared so that the mass ratio of polytetrafluoroethylene to cerium oxide was different from each other.

Six sheets of carbon paper were prepared as porous substrates. The anode-side microporous layer (MPL) forming slurry prepared above is applied to the surface of each carbon paper using a die coater, dried and then fired to form a microporous layer (MPL) on the porous base layer. ) was laminated, and the anode-side gas diffusion layer was prepared in which the mass ratio of polytetrafluoroethylene to cerium oxide in the microporous layer was different from each other.

(Preparation of cathode side gas diffusion layer)
Six sheets of carbon paper were prepared as porous substrates. A slurry for forming a microporous layer (MPL) containing carbon particles, polytetrafluoroethylene (PTFE), and cerium oxide (CeO ₂ ) is prepared, coated on carbon paper using a die coater, dried, and then fired. In this way, six cathode-side gas diffusion layers in which a microporous layer (MPL) was laminated on a porous base material layer were manufactured.

(Preparation of laminate)
Using the anode gas diffusion layer and cathode gas diffusion layer obtained above, an anode gas diffusion layer/anode catalyst layer/electrolyte membrane/cathode catalyst layer/cathode gas diffusion layer are laminated in this order. By constructing a laminate and sandwiching it between a pair of separators, six types of fuel cells were fabricated, each having a different mass ratio of polytetrafluoroethylene to cerium oxide in the anode side microporous layer.

Note that the anode-side catalyst layer and the cathode-side catalyst layer were arranged so that the microporous layer (MPL) of the adjacent gas diffusion layer faced each other.

<Evaluation of output performance>
The six types of fuel cells produced were evaluated for output performance after a durability test in the same manner as in Experimental Example 1 above.

The results obtained are shown in FIG. 4 as relative values based on the case where the mass ratio of polytetrafluoroethylene to cerium oxide in the anode side microporous layer was 5.5.

FIG. 4 is a diagram showing the relationship between the mass ratio of polytetrafluoroethylene to cerium oxide in the anode-side microporous layer and output performance. The horizontal axis of the graph is the mass ratio of polytetrafluoroethylene to cerium oxide in the anode side microporous layer, and the vertical axis of the graph is the output performance (%) of the obtained fuel cell.

From FIG. 3, it can be seen that a fuel cell with high output performance can be obtained if the mass ratio of polytetrafluoroethylene to cerium oxide in the anode side microporous layer is in a range of 5.5 or more.

100 Laminated body 10 Anode side gas diffusion layer 11 Anode side diffusion layer base material layer 12 Anode side microporous layer 15 Anode side catalyst layer 20 Cathode side gas diffusion layer 21 Cathode side diffusion layer base material layer 22 Cathode side microporous layer 25 Cathode Side catalyst layer 30 Electrolyte membrane

Claims (1)

A laminate for a fuel cell in which an anode side gas diffusion layer, an anode side catalyst layer, an electrolyte layer, a cathode side catalyst layer, and a cathode side gas diffusion layer are stacked in this order,
The anode side gas diffusion layer and the cathode side gas diffusion layer are laminates in which a microporous layer is laminated on a diffusion layer base material layer,
The microporous layer includes carbon particles, polytetrafluoroethylene, and cerium oxide,
The mass ratio of the polytetrafluoroethylene to the cerium oxide in the anode side gas diffusion layer is 5.5 or more and less than 20,
The mass ratio of the polytetrafluoroethylene to the cerium oxide in the cathode side gas diffusion layer is greater than 20 and less than or equal to 35 ;
Laminate for fuel cells.

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