JP4133789B2 - Method for producing fuel cell electrode-membrane assembly - Google Patents

Description

  The present invention relates to a method for producing an electrode-membrane assembly for a fuel cell, and more particularly to a method for producing an electrode-membrane assembly for a fuel cell by drying an undried electrode-membrane assembly.

FIG. 6 is a cross-sectional view showing a conventional fuel cell electrode-membrane assembly.
In the fuel cell electrode-membrane assembly 100, the negative electrode side base layer 102 is stacked on the negative electrode side diffusion layer 101, the negative electrode layer 103 is stacked on the negative electrode side base layer 102, and the electrolyte membrane 104 is stacked on the negative electrode layer 103. Then, the positive electrode layer 105 is laminated on the electrolyte membrane 104, the positive electrode base layer 106 is laminated on the positive electrode layer 105, and the positive electrode diffusion layer 107 is laminated on the positive electrode base layer 106.

When manufacturing this fuel cell electrode-membrane assembly, a method using alcohol is known in order to ensure the bondability of the fuel cell electrode-membrane assembly (see, for example, Patent Document 1).
JP-A-7-130375

  In the technique of this publication, for example, carbon as a catalyst is held on the carbon of the positive electrode layer, a film made of Nafion (registered trademark: DuPont) is formed on the surface, and a part of the Nafion film is gelled with alcohol. By improving the binding property between carbons which are dissolved in the carbon and hold platinum, the bonding property of the fuel cell electrode-membrane assembly is kept good.

By the way, in a fuel cell electrode-membrane assembly, a positive electrode layer, an electrolyte membrane, etc. are stacked in an undried state to form an electrode-membrane assembly, and then this undried electrode-membrane assembly is Some are dried while being pressed with a force (2 × 10 ³ to 4 × 10 ³ kPa).
Thus, when the electrode-membrane assembly in an undried state is dried, the positive electrode layer and the electrolyte membrane are brought into close contact with each other by applying pressure with a large force.

  However, this electrode-membrane assembly for a fuel cell needs to pressurize the electrode-membrane assembly in an undried state with a large force when it is dried. For example, the positive electrode layer may be crushed. This example will be described in detail in the next figure.

FIG. 7 is a cross-sectional view showing a main part of a conventional electrode-membrane assembly for a fuel cell.
The electrode-membrane assembly 100 is dried while pressing the overlapped electrode-membrane assembly 100 with a large force (2 × 10 ³ to 4 × 10 ³ kPa) as indicated by an arrow.
For this reason, for example, a large force is applied from the positive electrode base layer 106 to the positive electrode layer 105, and the positive electrode layer 105 may be crushed by the positive electrode base layer 106.
Thus, when the positive electrode layer 105 is crushed, it is difficult to secure pores (not shown) of the positive electrode layer 105, and it is difficult to improve the power generation performance of the fuel cell electrode-membrane assembly 100. There is.

  An object of the present invention is to provide a method for producing a fuel cell electrode-membrane assembly capable of ensuring the power generation performance of the fuel cell electrode-membrane assembly.

Invention, a base layer on one side is applied to the diffusion layer on one side of the positive and negative electrodes, while the underlying layer of the one side is undried, one electrode layer of the positive and negative electrodes wherein according to claim 1 The electrode layer is applied to the base layer on one side , the electrolyte layer is applied to the one electrode layer while the one electrode layer is undried, and the other electrode of the positive and negative electrodes is applied to the one electrode layer. applying a layer on the electrolyte layer, while the other electrode layer is undried, among other side bilayers of the underlying layer obtained by coating the other side of the diffusion layer of the positive and negative electrodes, the other The base layer on the side is overlaid on the other electrode layer, the diffusion layer on one side of the positive / negative electrode, the base layer on the one side, the one electrode layer on the positive / negative electrode, the electrolyte membrane, the other electrode layer of the negative electrode, the diffusion layer on the other side of the base layer and the positive and negative electrodes of the other side is conductive undried state of being stacked in this order - a membrane assembly, the undried state of the electrode - for a fuel cell electrode by drying the membrane assembly - a method for producing a membrane assembly, the carbon particle base layer on the other side of the bilayers The value obtained from the binder and the solvent, the mass sum of the carbon particles, the binder and the solvent as the denominator and the mass of the solvent as the numerator is called the solvent content of the underlayer, and the solvent content of the underlayer is 80 and 98 wt%, in this state, and wherein the superposition of the base layer on the other side of the two-layer body to the other electrode layer of the positive and negative electrodes.

By setting the solvent content of the base layer constituting the bilayer to 80 to 98 wt%, the solvent is infiltrated into the binder of the base layer on the other side to swell the binder.
By allowing the solvent to penetrate into the binder and swelling the binder, the adhesiveness of the binder is enhanced. Therefore, when the superimposed base layer on the other side to the other electrode layer of the positive and negative electrodes, it is possible to suitably adhere the underlying layer on the other side to the electrode layer.
In this way, by increasing the adhesiveness of the binder, it is possible to reduce the force for pressing the electrode-membrane assembly when the electrode-membrane assembly in an undried state is dried.

Here, the reason why the solvent content of the underlayer is set to 80 to 98 wt% is as follows.
That is, when the solvent content of the underlayer is less than 80 wt%, the solvent content is too low and the binder is insufficiently swelled, and the other underlayer is suitably adhered to the other electrode layer of the positive and negative electrodes. There is a possibility that it cannot be done.
Therefore, by setting the solvent content of the underlayer to 80 wt% or more, the binder is swelled well, and the underlayer on the other side is suitably adhered to the other electrode layer of the positive and negative electrodes .

On the other hand, if the solvent content of the underlayer exceeds 98 wt%, the solvent content is too high and the solvent may flow out of the other underlayer.
Therefore, by setting the solvent content of the underlayer to 98 wt% or less, the solvent is prevented from flowing out of the other underlayer.

The invention according to claim 2 is characterized in that the solvent is sprayed onto the other underlayer immediately before the other underlayer of the bilayer body is overlaid on the other electrode layer of the positive and negative electrodes. The solvent content is 80 to 98 wt%.

Here, as a method of causing the solvent to penetrate into the binder of the other underlayer, the electrode layer may contain a solvent.
However, if a solvent is included in the electrode layer, the catalyst in the electrode layer may flow out together with the solvent.

Therefore, in claim 2, the solvent content is determined to be 80 to 98 wt% by spraying the solvent to the base layer on the other side of the bilayer body.
In this way, by directly spraying the solvent on the other underlayer, the catalyst in the electrode layer is prevented from flowing out together with the solvent.

In addition, as another method of causing the binder of the other side underlayer to swell and swell, when applying the other side underlayer to the diffusion layer on the other side of the positive / negative electrode, It is conceivable that the solvent content of the underlayer is 80 to 98 wt%.
However, there is a time difference between the formation of the bilayer body and the overlapping of the formed bilayer body with the other electrode layer of the positive and negative electrodes. During this time difference, the solvent of the underlayer on the other side may volatilize and the solvent content may be less than 80 wt%.

Therefore, in claim 2, immediately before the two-layer body is overlaid on the other electrode layer of the positive and negative electrodes, the solvent is directly sprayed on the base layer on the other side .
As described above, the solvent is directly blown onto the other underlayer immediately before the two-layer body is overlaid, thereby preventing the solvent from volatilizing and the solvent content from being less than 80 wt%.
Therefore, by reliably increasing the adhesion of the base layer on the other side, it is possible to reduce the force of pressing the electrode-membrane assembly when the electrode-membrane assembly is dried.

  The invention according to claim 3 is characterized in that a load of 0.5 to 1.5 kPa is applied to the electrode-membrane assembly when the electrode-membrane assembly in an undried state is dried.

Here, in general, when an electrode-membrane assembly in an undried state is dried, it is necessary to press the electrode-membrane assembly with a large force in order to make the electrode-membrane assembly adhere well.
Thus, there exists a possibility that an electrode layer may be crushed by pressurizing an electrode-membrane assembly with big force, for example.

Therefore, in claim 3, the load applied to the electrode-membrane assembly is suppressed to a small value of 0.5 to 1.5 kPa by increasing the adhesion by setting the solvent content of the underlayer to 80 to 98 wt%.
Thus, by suppressing the load applied to the electrode-membrane assembly to a small value, for example, the electrode layer can be prevented from being crushed when the electrode-membrane assembly in an undried state is dried.

  In the invention according to claim 1, the electrode layer is prevented from being crushed by reducing the force of pressing the electrode-membrane assembly by setting the solvent content of the underlayer to 80 to 98 wt%, and the power generation performance of the electrode-membrane assembly There is an advantage that can be secured.

In the invention according to claim 2, immediately before overlapping the bilayers in the electrode layer, by blowing the solvent in the underlying layer of the other side, reliably improving the adhesion of the other side of the base layer, the electrode - membrane assembly There is an advantage that the power generation performance can be reliably ensured.

  The invention according to claim 3 has an advantage that the power generation performance of the electrode-membrane assembly can be ensured by suppressing the load applied to the electrode-membrane assembly to be small and preventing the electrode layer from being crushed.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is an exploded perspective view showing a fuel cell unit provided with an electrode-membrane assembly for a fuel cell according to the present invention.
The fuel cell unit 10 is composed of a plurality (two) of fuel cell units (cells) 11, 11.
This single fuel cell 11 includes a negative separator 13 and a positive separator 14 on both sides of a fuel cell electrode-membrane assembly 12.

The fuel cell electrode-membrane assembly 12 includes a negative electrode side diffusion layer 21, a negative electrode side base layer 22, a negative electrode layer 23, an electrolyte membrane 24, a positive electrode layer 25, a positive electrode side base layer (base layer) 26, and a positive electrode side diffusion. The layer 27 is laminated.
The negative electrode side diffusion layer 21 and the positive electrode side diffusion layer 27 constitute both sides of the fuel cell electrode-membrane assembly 12.

The negative electrode side separator 13 is laminated on the negative electrode side diffusion layer 21. The flow path groove 15 of the negative electrode side separator 13 is covered with the negative electrode side diffusion layer 21, and the hydrogen gas flow path 17 is formed by the negative electrode side diffusion layer 21 and the flow path groove 15.
Further, the positive electrode side separator 14 is laminated on the positive electrode side diffusion layer 27. The flow path groove 16 of the positive electrode side separator 14 is covered with the positive electrode side diffusion layer 27, and the oxygen gas flow path 18 is formed by the positive electrode side diffusion layer 27 and the flow path groove 16.

The electrode-membrane assembly 12 for a fuel cell includes a negative electrode side diffusion layer 21, a negative electrode side base layer 22, a negative electrode layer 23, an electrolyte membrane material 24, a positive electrode layer 25, a positive electrode side base layer 26, and a positive electrode side diffusion layer 27. It is a thing.
Thus, the fuel cell unit 10 is configured by providing a plurality of fuel cell units 11 (only two are shown in FIG. 1).
The fuel cell electrode-membrane assembly 12 will be described in detail with reference to FIG.

According to the fuel cell unit 10, the hydrogen gas is supplied to the hydrogen gas flow path 17 and the oxygen gas is supplied to the oxygen gas flow path 18, thereby causing electrons (e ⁻ ) to flow as indicated by arrows and generating a current. .

FIG. 2 is an explanatory view showing a fuel cell electrode-membrane assembly according to the present invention.
In the fuel cell electrode-membrane assembly 12, the negative electrode side base layer 22 is stacked on the negative electrode side diffusion layer 21, the negative electrode layer 23 is stacked on the negative electrode side base layer 22, and the electrolyte membrane 24 is stacked on the negative electrode layer 23. Then, the positive electrode layer 25 is laminated on the electrolyte membrane 24, the positive electrode base layer 26 is laminated on the positive electrode layer 25, and the positive electrode side diffusion layer 27 is laminated on the positive electrode side base layer 26.

As an example, the negative electrode side diffusion layer 21 and the positive electrode side diffusion layer 27 are obtained by subjecting porous carbon paper to a water repellent treatment.
The negative electrode side base layer 22 is composed of, for example, granular carbon (carbon particles) 28, a binder 29, and a solvent (not shown).
For example, thermoplastic fluororesin (THV) is used as the binder 29, and NMP (N-methyl-2.pyrrolidone), methyl ethyl ketone (MEK), or the like is used as the solvent.

By using a thermoplastic fluororesin (THV) as the binder 29, the negative electrode side underlayer 22 is made a layer having excellent water repellency.
The binder 29 is not limited to thermoplastic fluororesin (THV), and the solvent is not limited to NMP (N-methyl-2.pyrrolidone) or methyl ethyl ketone (MEK).

The positive electrode side underlayer 26 is composed of, for example, granular carbon (carbon particles) 31, a binder 32, and a solvent 45 (see FIG. 4B).
For example, a perfluorosulfonic acid polymer is used as the binder 32, and ethanol, methanol, 1-propanol, 2-propanol, or the like is used as the solvent 45.

By using a perfluorosulfonic acid polymer as the binder 32, the positive electrode base layer 26 is a layer having excellent water absorption.
The binder 32 is not limited to a perfluorosulfonic acid polymer, and the solvent 45 is not limited to ethanol, methanol, 1-propanol, and 2-propanol.

The negative electrode layer 23 is solidified by mixing a catalyst (electrode grain) 34 with a solvent for a negative electrode and drying the solvent after coating. The catalyst 34 of the negative electrode layer 23 is obtained by supporting a platinum-ruthenium alloy 36 as a catalyst on the surface of carbon 35.
The positive electrode layer 25 is solidified by mixing a catalyst (electrode grain) 37 in a positive electrode solvent and drying the solvent after coating. The catalyst 37 of the positive electrode layer 25 has platinum 39 supported on the surface of carbon 38 as a catalyst.

The electrolyte membrane 24 is obtained by applying a paste obtained by adding a solvent to a hydrocarbon-based solid polymer to the negative electrode layer 23, and then removing the solvent and drying the negative electrode layer 23 and the positive electrode layer 25. And solidified together.
Hereinafter, the manufacturing method of the electrode-membrane assembly 12 for fuel cells is demonstrated based on FIGS.

FIGS. 3A and 3B are diagrams illustrating an example in which the fuel cell electrode-membrane assembly according to the present invention is overlaid.
In (a), the negative electrode side base layer 22 is applied to the negative electrode side diffusion layer 21, and the negative electrode layer 23 is applied while the negative electrode side base layer 22 is undried.
The electrolyte membrane 24 is used while the negative electrode layer 23 is undried. The positive electrode layer 25 is applied while the electrolyte membrane 24 is not dried.
In (b), the positive electrode side base layer 26 is applied to the positive electrode side diffusion layer 27 to form the two-layer body 41.

4 (a) to 4 (c) are diagrams for explaining an example in which the binder of the positive base layer constituting the electrode-membrane assembly for a fuel cell according to the present invention is expanded.
In (a), the nozzle 43 of the spray coating device 42 is arranged above the positive electrode base layer 26, and the nozzle 43 is ejected from the nozzle 43 while the solvent 45 is jetted, and the surface 26a of the positive electrode base layer 26 is indicated by the arrow a. Move along.

In (b), a solvent 45 is applied to the surface 26 a of the positive electrode base layer 26.
Thereby, the solvent content of the positive electrode base layer 26 is set to 80 to 98 wt%.
However, the solvent content of the positive electrode base layer 26 is obtained by using the mass sum of the carbon particles 31, the binder 32, and the solvent 45 as a denominator and the mass of the solvent 45 as a numerator. That is,
Solvent content (wt%) of the positive electrode underlayer 26 =
The relationship of (mass of solvent 45) / [(mass of carbon particles 31) + (mass of binder 32) + (mass of solvent 45)] is established.

  Since a perfluorosulfonic acid polymer is used as the binder 32 of the positive electrode base layer 26, a solvent selected from ethanol, methanol, 1-propanol, 2-propanol and the like is used.

  The solvent 45 is applied to the surface 26a of the positive electrode base layer 26 so that the solvent content of the positive electrode base layer 26 is 80 to 98 wt%, whereby the solvent 45 is contained in the binder 32 as indicated by an arrow b (shown by a broken line). Infiltrate.

  In (c), by allowing the solvent 45 to permeate into the binder 32, the binder 32 swells.

Here, the reason why the solvent content of the solvent 45 (see FIG. 4B) of the positive electrode base layer 26 is set to 80 to 98 wt% is as follows.
That is, when the solvent content of the positive electrode underlayer 26 is less than 80 wt%, the content of the solvent 45 is too small and the binder 32 is insufficiently swelled to sufficiently secure the adhesion of the positive electrode underlayer 26. It is difficult.

For this reason, there is a possibility that the positive electrode base layer 26 cannot be suitably adhered to the positive electrode layer 25 (see FIG. 3A).
Therefore, by setting the solvent content of the positive electrode underlayer 26 to 80 wt% or more, the binder 32 is swollen well and the adhesion of the positive electrode underlayer 26 is improved.
By increasing the adhesion of the positive electrode base layer 26, the positive electrode base layer 26 is suitably adhered to the positive electrode layer 25.

On the other hand, if the solvent content of the positive electrode underlayer 26 exceeds 98 wt%, the content of the solvent 45 is too high and the solvent 45 may flow out of the positive electrode underlayer 26.
Therefore, the solvent content of the positive electrode side underlayer 26 is set to 98 wt% or less to prevent the solvent 45 from flowing out from the positive electrode side underlayer 26.

Incidentally, as another method of causing the solvent 45 to permeate the binder 32 of the positive electrode side base layer 26 to swell, it is conceivable to include the solvent 45 in the positive electrode layer 25 (see FIG. 3A).
However, if the solvent 45 is included in the positive electrode layer 25, the catalyst 37 (see FIG. 2) in the positive electrode layer 25 may flow out together with the solvent 45.

Therefore, the solvent content is determined to be 80 to 98 wt% by spraying the solvent 45 on the positive electrode underlayer 26 of the bilayer body 41.
Thus, by directly spraying the solvent 45 on the positive electrode base layer 26, the catalyst 37 (see FIG. 2) in the positive electrode layer 25 is prevented from flowing out together with the solvent 45.

As another method of causing the binder 45 of the positive electrode side underlayer 26 to swell and swell the solvent 45, the positive electrode side underlayer 26 is applied to the positive electrode side diffusion layer 27 to form the two-layer body 41. It is conceivable that the solvent content of the positive electrode underlayer 26 is 80 to 98 wt%.
However, after forming the two-layered body 41, a relatively large time difference occurs until the formed two-layered body 41 is superimposed on the positive electrode layer 25 (see FIG. 3A).
During this time difference, the solvent 45 of the positive electrode underlayer 26 may volatilize and the solvent content may be less than 80 wt%.

Therefore, immediately before the two-layer body 41 is overlaid on the positive electrode layer 25, the solvent 45 is directly sprayed onto the positive electrode underlayer 26.
In this way, the solvent 45 is directly sprayed onto the positive electrode base layer 26 immediately before the two-layer body 41 is overlaid, thereby preventing the solvent 45 from volatilizing and the solvent content from being less than 80 wt%.

FIGS. 5A and 5B are views for explaining an example of drying an electrode-membrane assembly for a fuel cell according to the present invention.
In (a), immediately after the binder 32 of the positive electrode base layer 26 is expanded, the bilayer body 41 is inverted so that the surface 26 a of the positive electrode base layer 26 faces the surface 25 a of the positive electrode layer 25.
In this state, the bilayer body 41 is moved as shown by an arrow c, and the positive electrode base layer 26 is placed on the positive electrode layer 25, thereby superimposing the bilayer body 41 on the positive electrode layer 25.
Thereby, the electrode-membrane assembly 12 in an undried state is obtained.

In (b), by placing 47 and 47 on the positive electrode side diffusion layer 27 of the electrode-membrane assembly 12 in the undried state, 0.5 to 1.5 kPa is applied to the electrode-membrane assembly 12 in the undried state. Apply the load.
As the weight 47, for example, two rod-shaped iron materials are prepared and placed on both sides 27a and 27a of the positive electrode side diffusion layer 27, respectively.

Adhesiveness of the positive electrode side underlayer 26 is enhanced by setting the solvent content of the positive electrode side underlayer 26 to 80 to 98 wt%. Therefore, the load applied to the electrode-membrane assembly 12 in an undried state can be suppressed to a small value of 0.5 to 1.5 kPa.
Thereby, a necessary load can be applied to the electrode-membrane assembly 12 in an undried state by a simple method of placing the weights 27, 27 on the positive electrode side diffusion layer 27.

In a state where a load of 0.5 to 1.5 kPa is applied to the electrode-membrane assembly 12 in the undried state, the electrode-membrane assembly 12 in the undried state is heated by the heater 48 as indicated by an arrow d.
The solvent is evaporated from the undried electrode-membrane assembly 12 as shown by an arrow e to obtain the dried fuel cell electrode-membrane assembly 12 shown in FIG.
Thus, the manufacturing process of the fuel cell electrode-membrane assembly 12 is completed.

  As described above, according to the method of manufacturing the fuel cell electrode-membrane assembly 12, the positive electrode side base layer 26 constituting the two-layer body 41 has a solvent content of 80 to 98 wt%. The solvent 45 (see FIG. 4B) is infiltrated into the binder 32 of the base layer 26 to swell the binder 32.

By causing the solvent 45 to penetrate into the binder 32 and causing the binder 32 to swell, the adhesion of the positive electrode underlayer 26 is increased.
Therefore, when the positive electrode base layer 26 is superposed on the positive electrode layer 25, the positive electrode base layer 26 can be suitably adhered to the positive electrode layer 25.
As a result, the interface resistance between the positive electrode layer 25 and the positive electrode underlayer 26 can be reduced, and the power generation performance of the fuel cell electrode-membrane assembly 12 can be suitably maintained.

Furthermore, when the electrode-membrane assembly 12 in an undried state is dried by increasing the adhesion of the positive electrode base layer 26, the force for pressing the electrode-membrane assembly 12 is set to 0.5 to 1. It can be kept as small as 5 kPa.
In this way, by suppressing the pressure applied to the electrode-membrane assembly 12 in the undried state to be small, for example, the positive electrode layer 25 is prevented from being crushed when the electrode-membrane assembly 12 in the undried state is dried. To do. Thereby, the power generation performance of the fuel cell electrode-membrane assembly 12 can be suitably maintained.

Here, when the electrode-membrane assembly 12 in an undried state is dried, the electrode-membrane assembly 12 in an undried state is subjected to a large force (2 × 10 ³ to 4 × 10 ³ kPa) as in the prior art. In order to pressurize, it is necessary to set the electrode-membrane assembly 12 in an undried state in a pressurizing device, and pressurize the electrode-membrane assembly 12 in an undried state with the pressurizing device.
For this reason, the process of pressurizing the electrode-membrane assembly 12 in an undried state takes time, which hinders productivity.

On the other hand, according to the manufacturing method of the electrode-membrane assembly 12 for a fuel cell according to the present invention, the positive electrode-side diffusion layer 27 is reduced by suppressing the load applied to the electrode-membrane assembly 12 in an undried state. It is possible to apply a necessary load to the undried electrode-membrane assembly 12 by a simple method of placing the weights 27, 27.
Thereby, since the electrode-membrane assembly 12 in an undried state can be pressurized without taking time, productivity can be increased.

Here, the reason why the solvent content of only the positive electrode base layer 26 is set to 80 to 98 wt% in the above embodiment will be described.
That is, after the negative electrode side underlayer 22 is applied, the negative electrode layer 23 is immediately applied while the negative electrode side underlayer 22 is undried, and the electrolyte film 24 and the positive electrode layer 25 are sequentially applied to the negative electrode layer 23. Thus, the negative electrode layer 23, the electrolyte membrane 24, and the positive electrode layer 25 can be applied to the negative electrode base layer 22.
Therefore, the negative electrode side underlayer 22 can be adhered to the negative electrode layer 23 without setting the solvent content of the negative electrode side underlayer 22 to 80 to 98 wt%.

On the other hand, the positive electrode base layer 26 is applied to the positive electrode diffusion layer 27 to form a two-layer body 41, and the two-layer body 41 is overlaid on the positive electrode layer 25. For this reason, the positive electrode layer 25 cannot be applied immediately after the positive electrode base layer 26 is applied to the positive electrode diffusion layer 27.
Furthermore, since the positive electrode base layer 26 is located above the negative electrode layer 23, the electrolyte membrane 24, and the positive electrode layer 25, the weight of the negative electrode layer 23, electrolyte membrane 24, and positive electrode layer 25 on the positive electrode base layer 26. Can not be applied.

For this reason, it is difficult to satisfactorily adhere the positive electrode base layer 26 applied to the positive electrode diffusion layer 27 to the positive electrode layer 25.
Therefore, the solvent content of the positive electrode underlayer 26 is set to 80 to 98 wt% to improve the adhesion of the positive electrode underlayer 26 and to adhere the positive electrode underlayer 26 to the positive electrode layer 25.

For the reasons described above, of the negative electrode side underlayer 22 and the positive electrode side underlayer 26, only one of the underlayers on the upper side, that is, the positive electrode side underlayer 26 as illustrated in the embodiment, has a solvent content of 80 to 98 wt. % Is preferable.
Alternatively, when the negative electrode side underlayer (underlayer) 22 is on the upper side, it is preferable that only the negative electrode side underlayer 22 has a solvent content of 80 to 98 wt% as one underlayer.

  As described above, it is preferable that only one of the upper base layer on the upper side of the negative electrode side base layer 22 and the positive electrode side base layer 26 has a solvent content of 80 to 98 wt%. It is also possible to make the solvent content of both the underlayers of the positive electrode side underlayer 26 to be lower and the negative electrode side underlayer 22 to be lower be 80 to 98 wt%.

  In the embodiment described above, the binder 29 of the negative electrode side underlayer 22 is thermoplastic fluororesin (THV), the solvent is NMP (N-methyl-2.pyrrolidone) or methyl ethyl ketone (MEK), and the positive electrode side underlayer 26 is used. The example in which the binder 32 is perfluorosulfonic acid polymer and the solvent 45 is ethanol, methanol, 1-propanol, 2-propanol has been described. However, the present invention is not limited thereto, and the negative electrode side underlayer 22 and the positive electrode side underlayer 26 are not limited thereto. It is also possible to use the same binder and solvent.

Furthermore, in the above-described embodiment, the fuel cell electrode-membrane assembly 12 is made up of the negative electrode side diffusion layer 21, the negative electrode side base layer 22, the negative electrode layer 23, the electrolyte membrane 24, the positive electrode layer 25, and the positive electrode side base layer 26. However, the fuel cell electrode-membrane assembly 12 is not limited to this, and the positive electrode side diffusion layer 27, the positive electrode side underlayer 26, and the positive electrode layer are not limited thereto. 25, the electrolyte membrane 24, the negative electrode layer 23, the negative electrode side base layer 22, and the negative electrode side diffusion layer 21 may be laminated in this order.
In this case, as described above, it is preferable that only the negative electrode base layer 22 on the upper side has a solvent content of 80 to 98 wt%.

  In the above-described embodiment, the example in which the solvent 45 is applied to the surface 26a of the positive electrode base layer 26 by spraying has been described. However, the application of the solvent 45 is not limited to spraying and is applied by other application means. It is also possible.

  The present invention is suitable for a method for producing an electrode-membrane assembly for a fuel cell by drying an undried electrode-membrane assembly.

It is a disassembled perspective view which shows the fuel cell unit provided with the electrode-membrane assembly for fuel cells which concerns on this invention. It is explanatory drawing which shows the electrode-membrane assembly for fuel cells which concerns on this invention. It is a figure explaining the example which piles up the electrode-membrane assembly for fuel cells concerning the present invention. It is a figure explaining the example which swells the binder of the positive electrode side base layer which comprises the electrode-membrane assembly for fuel cells which concerns on this invention. It is a figure explaining the example which dries the electrode-membrane assembly for fuel cells which concerns on this invention. It is sectional drawing which shows the conventional electrode-membrane assembly for fuel cells. It is sectional drawing which shows the principal part of the conventional electrode-membrane assembly for fuel cells.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell unit, 11 ... Fuel cell single-piece | unit (cell), 12 ... Electrode-membrane assembly for fuel cells, 21 ... Negative electrode side diffusion layer, 22 ... Negative electrode side base layer (base layer), 23 ... Negative electrode layer, 24 ... electrolyte membrane, 25 ... positive electrode layer, 26 ... positive electrode side underlayer (underlayer), 27 ... positive electrode side diffusion layer, 28, 31 ... carbon (carbon particles), 29, 32 ... binder, 41 ... bilayer 45 ... Solvent 47 ... Weight.

Claims (3)

Apply the base layer on one side to the diffusion layer on one side of the positive and negative electrodes,
While the base layer on one side is undried, one of the positive and negative electrode layers is applied to the base layer on the one side ,
While this one electrode layer is undried, an electrolyte membrane is applied to the one electrode layer ,
While this electrolyte membrane is undried, the other electrode layer of the positive and negative electrodes is applied to the electrolyte layer ,
Among the two-layered body obtained by applying the other underlayer to the diffusion layer on the other side of the positive and negative electrodes while the other electrode layer is undried, the other underlayer is used as the other electrode. superimposed on the layer,
The diffusion layer on one side of the positive / negative electrode, the base layer on the one side, the one electrode layer on the positive / negative electrode, the electrolyte membrane, the other electrode layer on the positive / negative electrode, the base layer on the other side, and the An undried electrode-membrane assembly in which the diffusion layers on the other side of the positive and negative electrodes are laminated in this order ,
A method for producing an electrode-membrane assembly for a fuel cell by drying the electrode-membrane assembly in an undried state,
The underlayer on the other side of the bilayer is composed of carbon particles, a binder and a solvent,
The value obtained by using the mass sum of the carbon particles, the binder and the solvent as the denominator and the mass of the solvent as the numerator is called the solvent content of the underlayer,
The solvent content of the underlayer is 80 to 98 wt%,
In this state, the fuel cell electrode, characterized in that to superimpose the underlayer on the other side of the two-layer body to the other electrode layer of the positive and negative electrode - the manufacturing method of the membrane assembly. The solvent content is 80 to 98 wt% by spraying the solvent onto the other underlayer immediately before the other underlayer of the two-layer body is overlaid on the other electrode layer of the positive and negative electrodes. The method for producing a fuel cell electrode-membrane assembly according to claim 1.   The fuel cell according to claim 1 or 2, wherein a load of 0.5 to 1.5 kPa is applied to the electrode-membrane assembly when the electrode-membrane assembly in an undried state is dried. Of manufacturing electrode-membrane assembly for use.

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