JP2012204049A - Method for manufacturing membrane electrode assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for enhancing durability and power generation performance of a membrane electrode assembly.SOLUTION: The method for manufacturing the membrane electrode assembly comprises: (a) preparing an electrolyte precursor membrane that is a fluorine-based electrolyte resin membrane capable of obtaining ion conductivity by hydrolysis (S10); (b) impregnating the electrolyte precursor membrane with a fluorine-based solvent to swell the electrolyte precursor membrane (S20); (c) applying a catalyst ink on an external surface of the electrolyte precursor membrane while the electrolyte precursor membrane is swollen, to form an electrode precursor (S30); (d) drying the electrolyte precursor membrane in a state where an outer peripheral end of the electrolyte precursor membrane is fixed (S40); and (e) imparting ion conductivity to the electrolyte precursor membrane by hydrolysis (S50).

Description

  The present invention relates to a fuel cell.

  A polymer electrolyte fuel cell (hereinafter, also simply referred to as “fuel cell”) usually includes a membrane electrode assembly which is a power generator in which electrodes are arranged on both surfaces of an electrolyte membrane (Patent Document 1 below). The electrolyte membrane is a solid polymer thin film, and exhibits good proton conductivity in a wet state. By the way, the electrolyte membrane swells and shrinks according to its wet state. If the electrolyte membrane repeatedly swells and shrinks during the manufacturing process of the membrane / electrode assembly or during power generation, the electrode disposed in contact with the outer surface may be distorted. The occurrence of such strain causes a decrease in durability of the membrane / electrode assembly, such as detachment of the electrode from the electrolyte membrane and damage / deterioration of the electrode itself, and also causes a decrease in power generation performance of the fuel cell. Until now, it has been the actual situation that such a problem has not been sufficiently devised.

JP 2006-318809 A JP 2007-258022 A JP 2007-019872 A JP 2008-218261 A Japanese Unexamined Patent Publication No. 60-149631

  An object of the present invention is to provide a technique for improving the durability and power generation performance of a membrane electrode assembly.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A method for producing a membrane electrode assembly used in a fuel cell,
(A) preparing an electrolyte resin film capable of imparting ionic conductivity by hydrolysis;
(B) a step of swelling the electrolyte resin film;
(C) forming a catalyst electrode by disposing a conductive material carrying a catalyst on the outer surface of the electrolyte resin film while the electrolyte resin film is swollen;
(D) drying the electrolyte resin film in a state where the position of the outer peripheral end of the electrolyte resin film on which the catalyst electrode is formed is fixed;
(E) providing ion conductivity to the electrolyte resin membrane by hydrolysis;
A manufacturing method comprising:
According to this manufacturing method, the electrolyte resin film is swollen in the step (b) or the step (c) before the hydrolysis treatment, and the size in the direction along the surface of the electrolyte resin film is expanded in advance. Deformation due to swelling of the electrolyte resin film in the hydrolysis treatment is suppressed. Therefore, it can suppress that the adhesiveness (binding property) between an electrolyte resin film and a catalyst electrode falls in a hydrolysis process. Further, according to this manufacturing method, since the electrolyte membrane of the membrane electrode assembly is produced in a size that is close to that when it is swollen, deformation due to swelling / shrinkage of the electrolyte membrane during power generation of the membrane electrode assembly Is suppressed, the durability of the membrane electrode assembly is improved, and the power generation performance is improved.

[Application Example 2]
In the manufacturing method according to application example 1, the electrolyte resin film prepared in the step (a) is made of a fluorine-based electrolyte resin, and the step (b) A production method comprising a step of impregnating and swelling a solvent of a system.
According to this manufacturing method, since the electrolyte resin film is swollen with the fluorine-based solvent, the heat treatment can be omitted and the treatment time can be shortened in the drying step in the step (d). When the fluorine-based electrolyte resin film is swollen with a fluorine-based solvent, the electrolyte polymer in the electrolyte resin film is in a melt-dispersed state. If the catalyst electrode is formed when the electrolyte resin film is in that state, the adhesion between the electrolyte resin film and the catalyst electrode can be improved.

[Application Example 3]
The production method according to Application Example 1 or 2, further comprising:
(F) adjusting the wet state of the electrolyte resin film while fixing the position of the outer peripheral end of the electrolyte resin film swollen by hydrolysis.
According to this manufacturing method, it is possible to bring the membrane / electrode assembly into a desired wet state while suppressing drying and shrinkage of the electrolyte resin film swollen by hydrolysis.

  The present invention can be realized in various forms, for example, for controlling a manufacturing method of a membrane electrode assembly used in a fuel cell, a manufacturing apparatus that executes the manufacturing method, and the manufacturing apparatus. And a recording medium on which the program is recorded. The present invention can also be realized in the form of a membrane electrode assembly manufactured by the above manufacturing method or manufacturing apparatus, a fuel cell including the membrane electrode assembly, a vehicle equipped with the fuel cell, and the like.

Schematic which shows the structure of a fuel cell provided with a membrane electrode assembly. Explanatory drawing which shows the procedure of the manufacturing process of a membrane electrode assembly. Schematic which shows typically the content of each process in the manufacturing process of a membrane electrode assembly. Schematic which shows typically the content of each process in the manufacturing process of a membrane electrode assembly. Explanatory drawing which shows the procedure of the manufacturing process of the membrane electrode assembly of a reference example. Schematic which shows typically the content of each process in the manufacturing process of the membrane electrode assembly of a reference example. Explanatory drawing which shows the experimental result by the inventor of this invention. Explanatory drawing which shows the experimental result by the inventor of this invention.

A. Example:
FIG. 1 is a schematic view showing the configuration of a fuel cell including a membrane electrode assembly as one embodiment of the present invention. This fuel cell 100 is a polymer electrolyte fuel cell that generates electric power by receiving supply of hydrogen (fuel gas) and oxygen (oxidizing gas) as reaction gases. The fuel cell 100 has a stack structure in which a plurality of single cells 110 are stacked.

  The single cell 110 includes a membrane electrode assembly 10 and two separators 21 and 22 that sandwich the membrane electrode assembly 10. The membrane electrode assembly 10 is a power generator in which two electrodes 2 and 3 (hereinafter also referred to as “anode 2” and “cathode 3”, respectively) are provided outside the electrolyte membrane 1.

  The electrolyte membrane 1 is composed of an ion exchange membrane having proton conductivity. Each of the anode 2 and the cathode 3 is an electrode having gas diffusibility formed on the outer surface of the electrolyte membrane 1, and supports a catalyst for promoting an electrochemical reaction. The anode 2 and the cathode 3 can be composed of catalyst-supported carbon. For example, platinum (Pt) can be used as the catalyst.

  A gas diffusion layer 5 is disposed on the outer surface of each of the two electrodes 2 and 3. The gas diffusion layer 5 is a layer for diffusing the reaction gas and spreading it over the entire electrodes 2 and 3. The gas diffusion layer 5 is formed by placing a porous fiber base material (for example, carbon fiber, graphite fiber, etc.) having conductivity, gas permeability, and gas diffusibility on the electrodes 2 and 3 and performing hot pressing. Can be formed. The gas diffusion layer 5 may be omitted.

  A seal portion 6 is formed at the outer peripheral end of the membrane electrode assembly 10. The seal portion 6 is formed by injection molding a resin member so as to cover the outer peripheral end of the electrolyte membrane 1. The seal portion 6 prevents the reaction gas from leaking from the region surrounded by the seal portion 6 and prevents a short circuit between the separators 21 and 22. In addition, although the manifold for supplying reaction gas to each single cell 110 is formed in the seal part 6, the illustration and description are abbreviate | omitted.

  The two separators 21 and 22 are respectively disposed outside the gas diffusion layer 5. More specifically, an anode separator 21 is disposed outside the gas diffusion layer 5 on the anode 2 side, and a cathode separator 22 is disposed outside the gas diffusion layer 5 on the cathode 3 side. Each of the separators 21 and 22 can be constituted by a gas-impermeable plate member (for example, a metal plate) having conductivity. A channel groove 25 for a reaction gas is formed over the entire electrode surface on the surface of each separator 21, 22 on the electrode 2, 3 side.

  With such a configuration, the two separators 21 and 22 function as gas flow paths for supplying reaction gas to the membrane electrode assembly 10 and collect electricity generated by the membrane electrode assembly 10. Also functions as a current collecting member. It should be noted that the flow channel 25 of each separator 21, 22 may be omitted. Further, a conductive flow path member such as a so-called expanded metal may be disposed between each separator 21, 22 and each gas diffusion layer 5. Furthermore, a flow path for the refrigerant may be formed in each separator 21 and 22.

  2-4 is explanatory drawing for demonstrating the manufacturing process of the membrane electrode assembly 10 of a present Example. FIG. 2 is a flowchart showing the procedure of the manufacturing process of the membrane electrode assembly 10, and FIGS. 3 (A) to (D) and FIGS. 4 (A) to (C) are the respective steps shown in FIG. It is the schematic which shows the content typically in process order.

  In step S10, an electrolyte precursor film 1f that is a precursor of the electrolyte film 1 is prepared (FIG. 3A). Here, in the present specification, the “precursor of an electrolyte membrane” means an electrolyte resin membrane in a previous stage that becomes an electrolyte membrane before proton conductivity is imparted by hydrolysis.

As the electrolyte precursor film 1f, an electrolyte resin film capable of imparting proton conductivity by hydrolysis can be used. For example, a fluorine-based resin having a —SO ₂ F group, more specifically, perfluorosulfonyl floyd, etc. Can be used. In addition, as the electrolyte precursor film 1f, a thin film such as styrene resin, polyimide, or polyamide may be used.

  In step S20, a fluorine-based solvent is applied and impregnated on the entire electrolyte precursor film 1f by the spray 200 to swell the electrolyte precursor film 1f (FIG. 3B). For example, hydrofluorether (HFE) can be used as the fluorine-based solvent. In this step, the electrolyte precursor film 1 f is preferably swollen to the size in the swollen state of the electrolyte film 1 during power generation of the fuel cell 100. 3B to 3D schematically show that the electrolyte precursor film 1f is swollen by showing the shape of the electrolyte precursor film 1f before swelling by a broken line. .

  In step S30, catalyst ink is applied to both surfaces of the swollen electrolyte precursor film 1f using the die coater 210, thereby forming two electrode precursors 2f and 3f in order (FIGS. 3C and 3D). ). Here, in this specification, the “catalyst ink” means a mixed solution in which a catalyst-supporting carbon and an electrolyte polymer are dispersed in a water-soluble solvent or an organic solvent. In this embodiment, as the catalyst ink, the catalyst-supporting carbon and the same kind of electrolyte polymer as contained in the electrolyte precursor film 1f are used as the fluorine-based solvent used to swell the electrolyte precursor film 1f in step S10. Use a dispersed one.

  The electrode precursors 2f and 3f formed by this process become the anode 2 and the cathode 3 by modifying the electrolyte polymer contained in the hydrolysis treatment described later. The electrode precursors 2f and 3f are preferably formed in an atmosphere in which the solvent is vaporized so that evaporation of the solvent impregnated in the electrolyte precursor film 1f is suppressed.

  In step S40, the electrolyte precursor film 1f on which the electrode precursors 2f and 3f are formed is attached to and held on the base 220, and the electrolyte precursor film 1f and the electrode precursors 2f and 3f are dried (FIG. 4A). . The base 220 includes a grip portion 221 that grips the outer peripheral end portion of the electrolyte precursor film 1f, and can hold the outer peripheral end position of the electrolyte precursor film 1f in a fixed state. The base 220 prevents the electrolyte precursor film 1f from drying and shrinking in the direction along the surface. FIG. 4A shows an electrolyte precursor film 1f that has been dried and shrunk in the thickness direction.

  In step S50, hydrolysis treatment is performed on the electrolyte precursor film 1f on which the electrode precursors 2f and 3f are formed. FIG. 4B shows the membrane electrode assembly 10 generated by the hydrolysis treatment. In FIG. 4B, the shape of the electrolyte precursor film 1f before the hydrolysis treatment is shown by a broken line.

Specific contents of the hydrolysis treatment are as follows.
(1) electrode precursor 2f, 3f an electrolyte precursor membrane 1f that is formed, is immersed in an alkaline solution (NaOH solution), -SO ₂ F groups electrolyte precursor membrane 1f and electrode precursor 2f, the electrolyte resin 3f having the denatured to -SO ₃ Na groups.
(2) After the electrode precursors 2f and 3f and the electrolyte precursor film 1f are washed with water, they are immersed in an acidic solution (H ₂ SO ₄ solution), and the —SO ₃ Na group modified in the previous step is further converted into —SO Denature into ₃ H groups.

  By this step, proton conductivity is imparted to the electrolyte resin contained in the electrolyte precursor film 1f and the electrode precursors 2f and 3f. That is, the electrolyte precursor film 1f becomes the electrolyte film 1 that is an ion exchange membrane, and the electrode precursors 2f and 3f become the anode 2 and the cathode 3, respectively.

  Here, in general, when this hydrolysis treatment is performed on the electrolyte resin film, the electrolyte resin film swells during the treatment process. However, the electrolyte precursor film 1f of the present example is dried in a state where the shrinkage in the direction along the surface is suppressed in the step S40 in the preceding stage (FIG. 4A). Therefore, in the electrolyte precursor film 1f of the present embodiment, the size expansion in the direction along the surface is suppressed during the hydrolysis treatment. Then, after the hydrolysis treatment, the electrolyte membrane 1 that is expanded in the thickness direction by the contained water is generated (FIG. 4B).

  In step S60, the membrane electrode assembly 10 in the wet state after the hydrolysis treatment is again attached to the base 220 and held, and the contained moisture is evaporated to adjust the wetness to a desired level (FIG. 4 ( C)). Also in this process, as in the process of step S40, the position of the outer peripheral end of the electrolyte membrane 1 is in a fixed state, so that the size of the electrolyte membrane 1 shrinks in the direction along the surface as the contained moisture evaporates. Is suppressed.

  5 and 6 are explanatory views for explaining a manufacturing process of a membrane electrode assembly 10a as a reference example. FIG. 5 is a flowchart showing the procedure of the manufacturing process of the membrane electrode assembly 10a of the reference example. FIG. 5 is substantially the same as FIG. 2 except that the two steps (steps S20 and S40) are omitted and the numbers of the corresponding drawings shown in each block are different. 6A to 6E are schematic views schematically showing the contents of the respective steps shown in FIG.

  In step S10, an electrolyte precursor film 1f is prepared in the same manner as described with reference to FIG. 3A (FIG. 6A). In the manufacturing process of this reference example, the catalyst ink is applied to both surfaces of the electrolyte precursor film 1f using the die coater 210 in step S30 without swelling the electrolyte precursor film 1f, and the electrode precursors 2f and 3f are applied. It forms (FIGS. 6B and 6C). The catalyst ink used in this step is the same as that described with reference to FIGS.

  In step S50, as described with reference to FIG. 4B, the electrolyte precursor film 1f on which the electrode precursors 2f and 3f are formed is hydrolyzed to generate the membrane electrode assembly 10a (FIG. 4). 6 (D)). In the manufacturing process of this reference example, the electrolyte precursor film 1f expands in the direction along the surface in addition to the thickness direction by the hydrolysis treatment. Therefore, in the produced membrane electrode assembly 10a, there is a possibility that stress is generated due to a difference in expansion amount due to swelling of the electrodes 2 and 3 and the electrolyte membrane 1. In FIG. 6 (D), the shape of the electrolyte precursor film 1f before swelling is indicated by a broken line, and the difference in the expansion amount between the electrolyte film 1 and the electrodes 2 and 3 is shown in the direction of expansion along each surface. This is schematically shown by the lengths of the arrows EDm and EDe.

  In step S60, the water content of the membrane / electrode assembly 10a swollen by the hydrolysis treatment is evaporated to adjust the membrane / electrode assembly 10a to a desired wetness (FIG. 6E). In step S60 of the manufacturing process of the reference example, the base 220 (FIG. 4C) is not used. That is, in the manufacturing process of the reference example, the wet state of the membrane electrode assembly 10a is adjusted without fixing the position of the outer peripheral end of the electrolyte membrane 1. Therefore, in step S60 of this reference example, a stress due to a difference in the amount of drying shrinkage between the electrolyte membrane 1 and the electrodes 2 and 3 may be generated in the membrane electrode assembly 10a. In FIG. 6 (E), the difference in dry shrinkage between the electrolyte membrane 1 and the electrodes 2 and 3 is schematically shown by the lengths of arrows CDm and CDe indicating the direction of shrinkage along the respective surfaces. is there.

  Here, the membrane electrode assembly 10 manufactured by the manufacturing process of the present embodiment (FIGS. 2 to 4) is compared with the membrane electrode assembly 10a manufactured by the manufacturing process of the reference example (FIGS. 5 and 6). Thus, power generation performance and durability are improved in the following points.

  In the membrane electrode assembly 10a of the reference example, as described above, due to the swelling of the electrolyte precursor film 1f in the hydrolysis treatment, the difference in expansion amount between the electrolyte membrane 1 and the electrodes 2 and 3 is caused due to the swelling of the electrolyte precursor film 1f. There is a high possibility that the resulting stress is generated and the adhesion between the electrodes 2 and 3 and the electrolyte membrane 1 is lowered. Further, when the membrane / electrode assembly 10a repeats power generation, the electrodes 2 and 3 are distorted due to repeated swelling and contraction of the electrolyte membrane 1, and the electrodes 2 and 3 are peeled off from the electrolyte membrane 1, There is a possibility of tearing in the direction along the surface.

  On the other hand, in the manufacturing process of the membrane electrode assembly 10 of the present embodiment, after the electrolyte precursor film 1f is swollen in step S20, in step S40, the electrolyte precursor film 1f is expanded in the direction along the surface. Dry to maintain size. This suppresses the electrolyte precursor film 1f from expanding in the direction along the surface in the subsequent hydrolysis treatment in step S50. Moreover, since the electrolyte membrane 1 is produced by being stretched to a size that swells during power generation, the degree of deformation due to swelling / contraction of the electrolyte membrane 1 during power generation is suppressed.

  Thus, with the membrane electrode assembly 10 of this example, the generation of stress due to the difference in expansion between the electrolyte membrane 1 and the electrodes 2 and 3 is suppressed during the manufacturing process and power generation. Therefore, the occurrence of displacement of the contact interface between the electrolyte membrane 1 and the electrodes 2 and 3 is suppressed. That is, a decrease in adhesion between the electrolyte membrane 1 and the electrodes 2 and 3 is suppressed, and the power generation performance and durability of the membrane electrode assembly 10 are improved.

  In the membrane electrode assembly 10a of the reference example, as described above, when the wetness is adjusted (step S60), stress is generated due to the difference in the amount of drying shrinkage between the electrolyte membrane 1 and the electrodes 2 and 3. There is a possibility that. Therefore, in the manufacturing process of the reference example, the adhesiveness between the electrolyte membrane 1 and the electrodes 2 and 3 is lowered, and the power generation performance and durability of the membrane electrode assembly 10a may be deteriorated.

  On the other hand, in the membrane electrode assembly 10 of the present embodiment, in step S60, the base 220 adjusts the wetness while suppressing drying shrinkage in the direction along the surface of the electrolyte membrane 1. Therefore, if it is a manufacturing process of a present Example, the fall of the adhesiveness between the electrolyte membrane 1 and the electrodes 2 and 3 will be suppressed, and the power generation performance and durability deterioration of the membrane electrode assembly 10 will be suppressed.

  Furthermore, in the manufacturing process of the membrane electrode assembly 10a of the reference example, the catalyst precursor is applied to the electrolyte precursor film 1f not impregnated with the fluorine-based solvent to form the electrode precursors 2f and 3f ( Step S30). On the other hand, in the manufacturing process of the membrane electrode assembly 10 of the present embodiment, the catalyst ink using the fluorine-based solvent is applied to the electrolyte precursor film 1f that has been impregnated and swollen with the fluorine-based solvent. Thus, electrode precursors 2f and 3f are formed (steps S20 and S30).

  That is, in the manufacturing process of the present embodiment, in step S30, the electrolyte polymer of the electrolyte precursor film 1f is dispersed and melted by the fluorine-based solvent, and is easily compatible with the catalyst ink. Therefore, in the membrane electrode assembly 10 of the present example, the adhesion between the electrolyte membrane 1 and the electrodes 2 and 3 is improved as compared with the membrane electrode assembly 10a of the reference example.

  FIG. 7 is an explanatory diagram showing experimental results by the inventors of the present invention. FIG. 7 shows a graph in which the two vertical axes are the cell voltage and resistance, and the horizontal axis is the cell temperature. Here, “cell voltage” is the average value of the output voltage for each single cell, and “cell temperature” is the average value of the operating temperature for each single cell. Further, the “resistance” is an average value of internal resistance for each single cell measured by the impedance method.

The inventor of the present invention uses the sample A of the membrane electrode assembly 10 prepared by the manufacturing process of the present embodiment (FIGS. 2 to 4) and the membrane electrode manufactured by the manufacturing process of the reference example (FIGS. 5 and 6). A fuel cell was constructed using sample B of the joined body 10a, and the power generation performance was verified. Specifically, these fuel cells were output at a constant current, and the operating temperature was changed to measure the cell voltage and resistance for each cell temperature. The solid line graphs A _VT and A _RT are graphs of the cell voltage and resistance measured in the fuel cell using the sample A, respectively, and the broken line graphs B _VT and B _RT are respectively graphs in the fuel cell using the sample B. It is the graph of the measured cell voltage and resistance.

  Here, in general, in the membrane / electrode assembly, when the adhesion between the electrolyte membrane and the electrode decreases, the contact resistance between the electrolyte membrane and the electrode increases. In addition, moisture tends to stay between the electrolyte membrane and the electrode, or strain or laceration generated in the electrode. For this reason, the mobility and drainage of water inside the membrane electrode assembly is lowered, and the flowability of the reaction gas is lowered. Thus, when the adhesiveness between the electrolyte membrane and the electrode is lowered, the power generation performance of the membrane electrode assembly is lowered.

  Compared to the fuel cell using sample B, the fuel cell using sample A was able to output a higher cell voltage over the entire cell temperature. And the difference of both cell voltage became large, so that cell temperature was high. Further, in the fuel cell using Sample A, the state of low resistance was maintained over the entire cell temperature as compared with the fuel cell using Sample B. And the difference of both resistance became large, so that cell temperature was high.

  This is because the sample A has better adhesion between the electrolyte membrane 1 and the electrodes 2 and 3 than the sample B, and the contact resistance between the electrolyte membrane 1 and the electrodes 2 and 3 is reduced. In addition, it is presumed that the moisture balance in the interior was well maintained. As a result of this experiment, the membrane electrode assembly 10 of the present example is suppressed from lowering the adhesion between the electrolyte membrane 1 and the electrodes 2 and 3 and the power generation performance compared to the membrane electrode assembly 10a of the reference example. Has been shown to improve.

  FIG. 8 is an explanatory diagram showing experimental results by the inventors of the present invention. FIG. 8 shows a graph in which the vertical axis represents the cell voltage, and the horizontal axis represents the number of cooling / heating cycles. Here, the “number of cooling / cooling cycles” means the number of times the cell temperature is periodically changed between −20 ° C. and 80 ° C.

The inventor of the present invention creates a fuel cell using the above-described sample A and a fuel cell using sample B, and continues output at a constant current for each fuel cell and at a constant cycle. The cell temperature was changed. And the change of the cell voltage for every cycle number of the change of the cell temperature was measured. Graph A _VC is a graph of the cell voltage measured in the fuel cell using Sample A, and Graph B _VC is a graph of the cell voltage measured in the fuel cell using Sample B.

  In the fuel cell using Sample B, the cell voltage showed a tendency to decrease with an increase in the number of cool / heat change cycles. In particular, when the number of cool / heat change cycles became larger than a certain value, the tendency to decrease became remarkable. On the other hand, in the fuel cell using Sample A, the cell voltage remained almost constant regardless of the increase in the number of cooling / heating change cycles. Further, the cell voltage of the fuel cell using Sample A showed a value higher than the cell voltage of the fuel cell using Sample B over the entire range of the cooling change cycle number.

  In Sample A, the membrane electrode assembly 10 is manufactured in a state where the electrolyte membrane 1 is stretched to the swollen size during power generation, and deformation due to swelling / shrinkage of the electrolyte membrane 1 during power generation occurs. It is speculated that this is because the adhesion between the electrolyte membrane 1 and the electrodes 2 and 3 was maintained. From this experiment, it was shown that the membrane electrode assembly 10 of this example had higher durability than the membrane electrode assembly 10a of the reference example.

  Thus, according to the manufacturing process of the membrane electrode assembly 10 of the present embodiment, deformation due to swelling of the electrolyte membrane 1 can be suppressed, and the adhesion between the electrolyte membrane 1 and the electrodes 2 and 3 can be improved. it can. Therefore, in the membrane electrode assembly 10, the occurrence of distortion in the electrodes 2 and 3 is suppressed, and the durability and power generation performance of the membrane electrode assembly 10 can be improved.

B. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

B1. Modification 1:
In the above embodiment, the electrolyte precursor film 1f is swollen by impregnating with a fluorine-based solvent (step S20 in FIG. 2, FIG. 3A). However, the electrolyte precursor film 1f may be swollen by another solvent. For example, it is possible to swell with water using a surfactant or the like. The solvent may be appropriately selected according to the type of the electrolyte resin constituting the electrolyte precursor film 1f, and may be any solvent that can disperse the electrolyte polymer contained in the electrolyte precursor film 1f.

  When the electrolyte precursor film 1f is swollen with a fluorine-based solvent, the evaporating property of the fluorine-based solvent is high, so that the drying process in step S40 can be performed at room temperature in a short time. . Further, as described in the above embodiment, the affinity between the electrolyte precursor film 1f and the catalyst ink can be improved, and the binding property between the electrolyte film 1 and the electrodes 2 and 3 is improved. Therefore, in step S20, the electrolyte precursor film 1f is preferably swollen with a fluorine-based solvent.

B2. Modification 2:
In the above embodiment, in step S60 (FIGS. 2 and 4C), the base electrode 220 is used to fix the membrane electrode assembly 10 in a wet state while the position of the outer peripheral end of the electrolyte membrane 1 is fixed. It was adjusted. However, in step S60, the wet state of the membrane electrode assembly 10 may be adjusted in a state where the position of the outer peripheral end of the electrolyte membrane 1 is not fixed. In step S60, by fixing the position of the outer peripheral end of the electrolyte membrane 1, the electrolyte membrane 1 in the wet state after the hydrolysis treatment is suppressed from drying and shrinking, and the electrolyte membrane 1 and the electrodes 2 and 3 It is suppressed that the adhesiveness between is reduced. In addition, the degree of deformation due to swelling of the electrolyte membrane 1 during power generation can be reduced, and the durability of the membrane electrode assembly 10 is improved.

B3. Modification 3:
In the above embodiment, the electrode precursors 2f and 3f were formed by applying the catalyst ink to the swollen electrolyte precursor film 1f. However, the electrode precursors 2f and 3f may be formed by transferring a catalyst-carrying film previously formed on a film substrate or the like to the outer surface of the swollen electrolyte precursor film 1f.

B4. Modification 4:
In the above embodiment, the electrode precursors 2f and 3f are formed on both surfaces of the swollen electrolyte precursor film 1f (step S30 in FIG. 2, FIGS. 3C and 3D). However, at least one of the electrode precursors 2f and 3f may be formed on the electrolyte precursor film 1f before the hydrolysis treatment.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 1f ... Electrolyte precursor membrane 2 ... Anode 3 ... Cathode 2f, 3f ... Electrode precursor 5 ... Gas diffusion layer 6 ... Seal part 10 ... Membrane electrode assembly 10a ... Membrane electrode assembly 21 ... Anode separator 22 ... Cathode Separator 25 ... Flow channel groove 100 ... Fuel cell 110 ... Single cell 200 ... Spray 210 ... Die coater 220 ... Base 221 ... Grip portion

Claims (3)

A method for producing a membrane electrode assembly used in a fuel cell,
(A) preparing an electrolyte resin film capable of imparting ionic conductivity by hydrolysis;
(B) a step of swelling the electrolyte resin film;
(C) forming a catalyst electrode by disposing a conductive material carrying a catalyst on the outer surface of the electrolyte resin film while the electrolyte resin film is swollen;
(D) drying the electrolyte resin film in a state where the position of the outer peripheral end of the electrolyte resin film on which the catalyst electrode is formed is fixed;
(E) providing ion conductivity to the electrolyte resin membrane by hydrolysis;
A manufacturing method comprising: The manufacturing method according to claim 1,
The electrolyte resin film prepared in the step (a) is made of a fluorine-based electrolyte resin,
The step (b) includes a step of impregnating the electrolyte resin film with a fluorine-based solvent and causing the electrolyte resin film to swell. The manufacturing method according to claim 1 or 2, further comprising:
(F) a step of adjusting the wet state of the electrolyte resin film while fixing the position of the outer peripheral edge of the electrolyte resin film swollen by hydrolysis;
A manufacturing method comprising:

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