JP5664519B2 - Manufacturing method of membrane electrode assembly - Google Patents

Description

  The present invention relates to a technique of a membrane electrode assembly used for a fuel cell.

  A fuel cell usually includes a membrane electrode assembly (MEA) which is a power generator in which electrodes are arranged on both sides of an electrolyte membrane. The electrode of the membrane electrode assembly is formed as a catalyst electrode carrying a catalyst for promoting a fuel cell reaction. In a method for producing a membrane / electrode assembly, generally, first, a conductive ink carrying a catalyst and an ionomer that is a polymer having ion conductivity are dispersed in an organic solvent or an inorganic solvent to produce a catalyst ink. And the membrane electrode assembly is manufactured by applying the catalyst ink to the electrolyte membrane and drying it to form a catalyst layer. As a method for producing a membrane electrode assembly, for example, Patent Document 1 below is known.

  Here, in the manufacturing process of the membrane electrode assembly, when the catalyst ink is directly applied to the electrolyte membrane, the electrolyte membrane absorbs the solvent, resulting in nonuniform drying shrinkage in the direction perpendicular to the catalyst layer surface and cracks in the catalyst layer. (Cracking) may occur. When cracks occur, there is a problem that durability when used as a fuel cell is low, and power generation distribution in the catalyst electrode becomes non-uniform during power generation, resulting in a decrease in power generation performance of the fuel cell.

JP 2007-048557 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to produce a good membrane / electrode assembly in which the occurrence of cracks in a catalyst layer is suppressed.

In order to solve at least a part of the problems described above, the present invention can take the following forms or application examples.
[Application Example 1]
A method for producing a membrane electrode assembly used in a fuel cell,
A step of forming a catalyst layer by applying a mixed solvent obtained by mixing water and an organic solvent, a catalyst-supporting conductive particle, and a catalyst ink obtained by mixing an ionomer to an electrolyte membrane;
The mixed solvent is absorbed by the mixed solvent having a weight of 30% to 60% with respect to the weight of the electrolyte membrane before absorption when only the mixed solvent is absorbed by the electrolyte membrane. As described above, a method for producing a membrane / electrode assembly, wherein a water ratio that is a ratio of a weight of the mixed water to a weight of the mixed solvent is adjusted.

  According to this method for manufacturing a membrane / electrode assembly, the water ratio of the mixed solvent used in the catalyst ink is adjusted so that the amount absorbed by the electrolyte membrane is relatively low. Specifically, the water ratio of the mixed solvent is adjusted so that the mixed solvent having a weight of 30% to 60% of the weight of the electrolyte membrane is absorbed by the electrolyte membrane. For this reason, when the catalyst ink using this mixed solvent is applied to the electrolyte membrane, the electrolyte membrane does not absorb a large amount of the mixed solvent. Therefore, when the electrolyte membrane expands due to absorption of the solvent and contracts due to subsequent drying, non-uniform expansion and contraction can be suppressed. As a result, generation of cracks in the catalyst layer formed on the electrolyte membrane can be suppressed.

[Application Example 2]
In the method for producing a membrane / electrode assembly according to Application Example 1, the mixed solvent is 30 [based on the weight of the electrolyte membrane before absorption when only the mixed solvent is absorbed into the electrolyte membrane. %] The production of a membrane electrode assembly in which the water ratio, which is the ratio of the weight of water to be mixed with respect to the weight of the mixed solvent, is adjusted so that the mixed solvent with a weight of 40% or less is absorbed. Method.

  According to this method of manufacturing a membrane / electrode assembly, the water ratio of the mixed solvent is adjusted so that the mixed solvent having a weight of 30% to 40% of the weight of the electrolytic membrane is absorbed by the electrolytic membrane. . Therefore, generation | occurrence | production of the crack of the catalyst layer formed on the electrolyte membrane can further be suppressed.

[Application Example 3]
The method for producing a membrane / electrode assembly according to Application Example 1 or 2, wherein the organic solvent is ethanol.
According to this method for producing a membrane / electrode assembly, the organic solvent can be produced using ethanol, which is easily available at a relatively low cost.

[Application Example 4]
A method for producing a membrane electrode assembly used in a fuel cell, wherein a mixed solvent in which water and an organic solvent are mixed, catalyst-supported conductive particles, and a catalyst ink in which an ionomer is mixed are applied to an electrolyte membrane. A step of forming a catalyst layer, wherein the mixed solvent has a water ratio of 60 wt% or more and less than 90 wt% that is a ratio of the weight of the mixed water to the weight of the mixed solvent Body manufacturing method.

  According to this method of manufacturing a membrane / electrode assembly, a mixed solvent having a water ratio of 60 wt% or more and less than 90 wt% is used. The inventors have found that the higher the water ratio, the smaller the amount of the mixed solvent absorbed by the electrolyte membrane. As a result, a mixed solvent having a water ratio of 60 wt% or more and less than 90 wt% has a relatively small amount absorbed by the electrolyte membrane. For this reason, when the catalyst ink using this mixed solvent is applied to the electrolyte membrane, the electrolyte membrane does not absorb a large amount of the mixed solvent. Therefore, when the electrolyte membrane expands due to absorption of the solvent and contracts due to subsequent drying, non-uniform expansion and contraction can be suppressed. As a result, generation of cracks in the catalyst layer formed on the electrolyte membrane can be suppressed.

[Application Example 5]
The method for producing a membrane / electrode assembly according to Application Example 5, wherein the water ratio is 60 wt% to 80 wt%.
It has been found through experiments by the inventors that a mixed solvent having a water ratio of 90 [wt%] or more has a strong hydrophobicity when applied to an electrolyte membrane. According to this method for producing a membrane / electrode assembly, a membrane / electrode assembly is produced using a mixed solvent having a water ratio of 60 wt% to 80 wt%. Therefore, it is possible to suppress the occurrence of cracks in the catalyst layer formed on the electrolyte membrane by using the catalyst ink adjusted so that the electrolyte membrane does not repel the mixed solvent.

[Application Example 6]
The method for producing a membrane / electrode assembly according to Application Example 5, wherein the water ratio is 70 [wt%] or more and 80 [wt%] or less.
According to this method for producing a membrane / electrode assembly, a membrane / electrode assembly is produced using a mixed solvent having a water ratio of 70 wt% to 80 wt%. Therefore, the generation of cracks in the catalyst layer formed on the electrolyte membrane can be further suppressed.

[Application Example 7]
A method for producing a membrane electrode assembly used in a fuel cell, wherein a mixed solvent in which water and an organic solvent are mixed, catalyst-supported conductive particles, and a catalyst ink in which an ionomer is mixed are applied to an electrolyte membrane. A step of forming a catalyst layer, and adjusting the water ratio, which is a ratio of the weight of the water to be mixed with respect to the weight of the mixed solvent, to thereby determine the degree of occurrence of cracks in the catalyst layer in the generated membrane electrode assembly A method for producing a membrane electrode assembly for controlling the temperature.

  According to this method for producing a membrane / electrode assembly, the degree of occurrence of cracks in the produced membrane / electrode assembly can be controlled by controlling the water ratio of the mixed solvent used in the catalyst ink.

[Application Example 8]
A method for producing a membrane electrode assembly used in a fuel cell, wherein a mixed solvent in which water and an organic solvent are mixed, catalyst-supported conductive particles, and a catalyst ink in which an ionomer is mixed are applied to an electrolyte membrane. A catalyst layer forming step of forming a catalyst layer, wherein the catalyst layer forming step is 30 [%] or more to 60% with respect to the weight of the electrolyte membrane before absorption when the catalyst ink is applied to the electrolyte membrane. [%] A water ratio adjusting step of adjusting a water ratio that is a ratio of the weight of the water to be mixed with respect to the weight of the mixed solvent so that the mixed solvent in the catalyst ink having a weight of the following is absorbed by the electrolyte membrane. The manufacturing method of a membrane electrode assembly provided with this.

  According to this method for producing a membrane / electrode assembly, the water ratio of the mixed solvent in the catalyst ink is adjusted so that the amount absorbed by the electrolyte membrane is relatively low. Specifically, the water ratio of the mixed solvent is adjusted so that the mixed solvent having a weight of 30% to 60% of the weight of the electrolyte membrane is absorbed by the electrolyte membrane. For this reason, when this catalyst ink is applied to the electrolyte membrane, the electrolyte membrane does not absorb a large amount of the mixed solvent. Therefore, when the electrolyte membrane expands due to absorption of the solvent and contracts due to subsequent drying, non-uniform expansion and contraction can be suppressed. As a result, generation of cracks in the catalyst layer formed on the electrolyte membrane can be suppressed.

  Note that the present invention can be realized in various modes. For example, it can be realized in various forms such as a fuel cell, a fuel cell system, a fuel cell manufacturing method, a membrane electrode assembly, a crack control method in a membrane electrode assembly, and a catalyst ink generation method.

It is explanatory drawing showing schematic structure of the fuel cell manufactured by applying this invention. It is process drawing which shows the manufacturing method of MEA12. It is explanatory drawing explaining the quantity of each material of a catalyst ink. It is explanatory drawing explaining the process of experiment. It is a graph which shows the correlation with a water ratio and solvent absorption weight ratio R. It is the surface image by SEM of MEA concerning each sample. It is explanatory drawing which showed the composition of the mixed solvent and solvent absorption weight ratio R of each sample.

Hereinafter, a fuel cell according to an embodiment of the present invention will be described based on examples with reference to the drawings.
A. First embodiment:
(A1) Configuration of fuel cell:
FIG. 1 is an explanatory view showing a schematic configuration of a single cell 10 in a fuel cell manufactured by adopting a method for manufacturing a membrane electrode assembly as one embodiment of the present invention. The figure schematically shows a cross section of the single cell 10. The fuel cell of the present embodiment is a polymer electrolyte fuel cell, and has a stack structure in which a plurality of single cells 10 are stacked. As shown in the figure, the unit cell 10 includes a membrane electrode assembly (hereinafter also referred to as MEA) 12 containing an electrolyte, a pair of gas diffusion layers 16 and 17 that sandwich the MEA 12 from both sides to form a sandwich structure, The sandwich structure is further composed of a pair of separators 20 and 21 that sandwich the sandwich structure from both sides.

  The MEA 12 includes an electrolyte membrane 13 and an anode (fuel electrode) 14 and a cathode (oxygen electrode) 15 that are electrodes formed on the surface of the electrolyte membrane 13 with the electrolyte membrane 13 interposed therebetween. The electrolyte membrane 13 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and exhibits good electrical conductivity in a wet state. The anode 14 and the cathode 15 are formed by applying a catalyst ink containing a catalyst that promotes an electrochemical reaction on the electrolyte membrane 13. This catalyst ink will be described in detail later.

  The gas diffusion layers 16 and 17 are configured by members having gas permeability and conductivity. In this embodiment, the gas diffusion layers 16 and 17 are formed of a carbon porous member such as carbon cloth or carbon paper. By providing the gas diffusion layers 16 and 17, the gas supply efficiency to the electrodes can be improved, the current collecting property between the separators 20 and 21 and the electrodes can be improved, and the electrolyte membrane 13 can be further protected. . Note that the gas diffusion layers 16 and 17 may be formed of another conductive porous member such as a metal porous material such as titanium or stainless steel instead of the carbon porous member.

  The separators 20 and 21 are formed of a gas-impermeable conductive member, for example, dense carbon that is compressed by carbon to be gas-impermeable, or a metal member. The separators 20 and 21 are formed with rib portions having a predetermined shape on the surfaces thereof, and hydrogen gas and oxidizing gas flow paths 20P and 21P are formed between the gas diffusion layers 16 and 17 adjacent to each other. To do.

  In FIG. 1, the ribs that form the gas flow paths are formed only on one side of each separator 20, 21, but in reality, the ribs are formed on both sides. Accordingly, the separators 20 and 21 form a gas flow path between the gas diffusion layers 16 and 17 and also serve to separate the flow of hydrogen gas and oxidizing gas between adjacent single cells. In addition, the shape of the rib formed on the surface of each separator may be any shape as long as the gas flow path is formed and the fuel gas or the oxidizing gas can be supplied to the gas diffusion layer. In this embodiment, the ribs formed on the surface of each separator have a plurality of groove-like structures formed in parallel.

  The configuration of the single cell 10 that is the basic structure of the fuel cell has been described above. When actually assembling as a fuel cell (fuel cell stack), a plurality of single cells 10 are stacked (for example, 100 sets), and a current collector plate, an insulating plate, and an end plate (not shown) are arranged at both ends thereof. Complete the fuel cell stack. Although illustration is omitted, in order to adjust the internal temperature of the stack structure, a refrigerant flow path through which the refrigerant passes may be provided between the single cells or every time a predetermined number of single cells are stacked. good. The refrigerant flow path may be provided between adjacent single cells and between the separator 21 provided in one single cell and the separator 20 of the other single cell provided adjacent thereto.

(A2) Manufacturing method of membrane electrode assembly (MEA):
FIG. 2 is a process diagram showing a method for manufacturing the MEA 12. When manufacturing MEA 12, first, each material required for the production | generation of the catalyst ink applied to an electrolyte membrane is mix | blended and mixed by a predetermined quantity (process S1). As shown in the figure, the materials to be mixed are catalyst-supporting carbon, ionomer, and mixed solvent. The mixed solvent is a solvent in which water and an organic solvent are mixed at a predetermined mixing ratio. In this embodiment, ethanol is used as the organic solvent. Further, platinum-supported carbon is used as the catalyst-supported carbon. The amount of the material to be mixed will be described in detail later.

  After the above materials are mixed, the platinum-carrying carbon and the ionomer are uniformly dispersed in the mixed solvent using a disperser (step S2). In this embodiment, an ultrasonic homogenizer is used as the disperser. The catalyst ink is produced in this way.

  When the catalyst ink is generated, the generated catalyst ink is directly applied on the electrolyte membrane with a uniform film thickness using a die coater (step S3). By applying the catalyst ink on the electrolyte membrane, a catalyst layer is formed on the electrolyte membrane. Then, MEA is manufactured by drying the electrolyte membrane in which the catalyst layer was formed with a warm air dryer (process S4). In this example, a Nafion membrane manufactured by DuPont was used as the electrolyte membrane. Nafion is a registered trademark.

(A3) Catalyst ink:
The catalyst ink used in this example will be described. FIG. 3 is an explanatory diagram for explaining the amount of each material of the catalyst ink prepared in the preparation step (step S1) of FIG. As shown in the figure, 10 [g] of platinum-supported carbon is used when producing the catalyst ink in this example. This platinum-supporting carbon is a catalyst in which platinum is mixed at a ratio of 30 [wt%] and carbon powder at a ratio of 70 [wt%]. As the ionomer, 32.8 [g] of Nafion (solid component: 21.6 [wt%]) manufactured by DuPont is used. The amount of the mixed solvent is determined so that the ratio of the solid content in the produced catalyst ink is 10 [wt%]. The solid content indicates the total weight of Nafion solid components, platinum, and carbon powder in the ionomer. In this way, the respective materials are mixed in the amounts shown in FIG. 3, and the catalyst ink is generated by the preparation step (step S1) and the dispersion step (step S2) described in FIG.

  The mixed solvent used for the catalyst ink will be described in detail. As described above, the mixed solvent is a solvent in which water and ethanol are mixed. In the following description, the ratio of mixing water and ethanol in the mixed solvent is expressed as a water ratio (unit: [wt%]) that is a ratio of the weight of water to the total weight of the mixed solvent. As a characteristic of the mixed solvent, it has been found through experiments by the inventors that the degree of absorption into the electrolyte membrane varies depending on the water ratio.

  Hereinafter, the process of the experiment conducted by the inventors and the result of the experiment will be described. FIG. 4 is an explanatory diagram for explaining an experimental process. In the experiment, first, an electrolyte membrane for experiment having a diameter of 60 mm (φ = 60 mm), which is the same as that used for manufacturing the MEA 12, was prepared (Step S11). In order to distinguish between the electrolyte membrane before absorption of the mixed solvent and the electrolyte membrane after absorption, the former is called an electrolyte membrane before absorption, and the latter is called an electrolyte membrane after absorption. Next, the weight of the prepared pre-absorption electrolyte membrane (hereinafter also referred to as pre-absorption electrolyte membrane weight) was measured (step S12). Thereafter, a mixed solvent having a predetermined water ratio was generated (step S13). Then, the entire prepared electrolyte membrane was immersed in the produced mixed solvent for 30 seconds (step 14). After soaking in the mixed solvent for 30 seconds, the excess mixed solvent was removed from the electrolyte membrane (post-absorption electrolyte membrane), and the weight of the post-absorption electrolyte membrane (hereinafter also referred to as post-absorption electrolyte membrane weight) was measured (step 15). . Thereafter, the difference between the weight of the electrolyte membrane after absorption and the weight of the electrolyte membrane before absorption (= electrolyte weight after absorption−electrolyte weight before absorption) was calculated (step S16). That is, the weight of the mixed solvent absorbed by the electrolyte membrane (hereinafter also referred to as solvent absorption weight) was calculated. Finally, the solvent absorption weight ratio R [%] was calculated by the following formula (1) (step S17).

  Solvent absorption weight ratio R [%] = (solvent absorption weight) / (electrolyte membrane weight before absorption) × 100 (1)

  The experimental steps of Steps S11 to S17 were performed in a plurality of types of mixed solvents with different water ratios. Thereafter, a correlation graph showing the correlation between the water ratio and the solvent absorption weight ratio R, with the water ratio [wt%] of the mixed solvent as the horizontal axis and the solvent absorption weight ratio R [%] for each water ratio as the vertical axis. Generated. FIG. 5 is a correlation graph derived by the inventors through the above experimental process. As shown in this correlation graph, it can be seen that the higher the water ratio of the mixed solvent, the smaller the solvent absorption weight ratio R in the electrolyte membrane.

  In this embodiment, based on this correlation graph, the water ratio of the mixed solvent used when manufacturing the MEA 12 is determined. Specifically, the water ratio of the mixed solvent is determined so as to suppress the amount of the mixed solvent absorbed by the electrolyte membrane when the catalyst ink is applied to the electrolyte membrane. Therefore, a catalyst ink was produced as a working sample 1 using a mixed solvent having a solvent absorption weight ratio R of about 30 [%], and used for the production of the MEA 12. Actually, based on the correlation graph, the water ratio of the mixed solvent corresponding to the solvent absorption weight ratio R = 33.1 [%] was 80 [wt%]. That is, a mixed solvent having a water ratio of 80 [wt%] was used in the MEA 12 manufacturing process described with reference to FIG.

  The manufacturing result of MEA 12 manufactured by adjusting the water ratio of the mixed solvent will be described with reference to FIG. FIG. 6 shows a surface image obtained by observing the surface of the catalyst layer of the MEA 12 manufactured in the working sample 1 with a scanning electron microscope (SEM). In addition, in FIG. 6, the manufacture result of MEA12 in the implementation samples 2 and 3 mentioned later and the comparative samples 1-3 was also shown.

  As shown in FIG. 6, it can be seen that cracks (cracks) are not observed in the catalyst layer of MEA 12 manufactured by applying the mixed solvent of Example Sample 1, and a good catalyst layer is formed. A good catalyst layer or MEA could be obtained without cracking in the catalyst layer by MEA using a fluorine electrolyte membrane. Therefore, the MEA 12 has high durability when applied to a fuel cell (single cell 10). Further, when power is generated as a fuel cell, the power generation distribution in the catalyst electrode can be made uniform to ensure high power generation performance.

  Next, the MEA 12 is manufactured using the mixed solvent of the implementation samples 2 and 3 and the comparison samples 1 to 3 as other implementation samples and comparison samples. FIG. 7 is an explanatory diagram showing the composition of the mixed solvent of Examples 1 to 3 including Comparative Example 1 and Comparative Samples 1 to 3 and the solvent absorption weight ratio R corresponding thereto. The water weight ratio ([wt%]) in the ink solvent composition shown in FIG. 7 is the water ratio [wt%] described above. As can be seen from FIG. 7, in each sample, the water ratio of the mixed solvent is changed every 10 [wt%] in the range of 40 [wt%] to 90 [wt%]. The surface image (SEM image) of the catalyst layer of the MEA 12 manufactured at each water ratio by changing the water ratio of the mixed solvent in this manner is shown in FIG.

  As shown in FIG. 6, it can be seen that cracks are not generated in the catalyst layer of the MEA 12 according to the working sample 1 and the working sample 2. Moreover, in the catalyst layer of MEA12 by Example sample 3, although a few cracks are seen, it turns out that generation | occurrence | production of a crack is suppressed.

  On the other hand, many cracks are generated in the catalyst layer of the MEA 12 by the comparative sample 1 and the comparative sample 2. Comparative Sample 3 has a water ratio of 90 [wt%], and when the catalyst ink generated by applying this mixed solvent is applied to the electrolyte membrane, the electrolyte membrane repels the catalyst ink, and the catalyst layer is not formed. It was possible. In addition, even when the water ratio is 90 [wt%] or more and the catalyst ink exhibits hydrophobicity as in Comparative Sample 3, a catalyst ink with reduced hydrophobicity is generated by adding a surfactant, It may be applied to the electrolyte membrane.

  From the above experimental data, when the MEA 12 is manufactured using a mixed solvent having a water ratio of about 60 [wt%] to 80 [wt%], that is, a solvent absorption weight ratio R of about 60 [%] to 30 [%], Can be suppressed. Preferably, when MEA 12 is produced using a mixed solvent having a water ratio of about 70 [wt%] to 80 [wt%], that is, a solvent absorption weight ratio R of about 40 [%] to 30 [%], generation of cracks Can be suppressed with high probability.

  As described above, the catalyst ink is generated using the mixed solvent whose water ratio is adjusted so that the solvent absorption weight ratio R is 60 [%] to 30 [%], and the MEA 12 is manufactured using the catalyst ink. Then, generation | occurrence | production of a crack can be suppressed in the catalyst layer formed. More preferably, when a catalyst ink is generated using a mixed solvent whose water ratio is adjusted so that the solvent absorption weight ratio R is 40 [%] to 30 [%], and the MEA 12 is manufactured using the catalyst ink, In the formed catalyst layer, the occurrence of cracks can be suppressed with high probability, and the MEA 12 without cracks can also be produced. As a result, MEA 12 is produced by applying a mixed solvent having a solvent absorption weight ratio R of 60 [%] to 30 [%], preferably 40 [%] to 30 [%]. Thus, high durability can be imparted to the MEA 12. Further, when power is generated as a fuel cell, the power generation distribution in the catalyst electrode can be made uniform to ensure high power generation performance.

B. Variation:
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 said Example, although ethanol was applied as an organic solvent using it for a mixed solution, the organic solvent to be used is not specifically limited. For example, various alcohols, various ethers, or a mixture thereof can be applied. Preferably, an alcohol having 1 to 3 carbon atoms is applied. Specifically, an organic solvent such as methanol, ethanol, 1-propanol, 2-propanol, t-butanol, or the like can be applied. In addition, when the above correlation graph is derived by experiment for each of these various organic solvents and each organic solvent is used as a catalyst ink, the correlation graph may be selected and applied according to the organic solvent to be used.

(B2) Modification 2:
In the above embodiment, an ultrasonic homogenizer is used as a disperser, but there is no particular limitation on the disperser to be used. For example, a disperser such as a nanomizer, a roll mill, a ball mill, a bead mill, or a jet mill can be used.

(B3) Modification 3:
In the said Example, although it applied using the die coater as a coating method which coats catalyst ink on an electrolyte membrane, there is no restriction | limiting in particular in a coating method. For example, a coating method such as a die coater, knife coater, bar coater, dip coater, spin coater, roll coater, curtain coater, doctor blade, or screen printing can be applied. In addition, as other methods for applying the catalyst ink to the electrolyte membrane, various methods for applying the catalyst ink to the electrolyte membrane, such as a method of spraying the catalyst ink on the electrolyte membrane and a method of immersing the electrolyte membrane in a container in which the catalyst ink is stored. Can be adopted.

(B4) Modification 4:
In the description of the above embodiment, the solvent absorption weight ratio R used in the manufacturing process of the MEA 12 is the weight of the solvent absorption weight (see Formula 1 above) with respect to the weight of the electrolyte membrane before absorption when only the mixed solvent is absorbed into the electrolyte membrane. Although defined as a ratio, it may be defined as follows and used in the MEA manufacturing process. That is, as shown in the following formula (2), when the produced catalyst ink is applied to the electrolyte membrane, the absorption of the weight of the mixed solvent in the catalyst ink absorbed by the electrolyte membrane (mixed solvent absorption weight in the catalyst ink) It may be defined as a weight ratio with respect to the weight of the pre-electrolyte membrane.

  Solvent absorption weight ratio R [%] = (mixed solvent absorption weight in catalyst ink) / (electrolyte membrane weight before absorption) × 100 (2)

10 ... Single cell 12 ... MEA
DESCRIPTION OF SYMBOLS 13 ... Electrolyte membrane 14 ... Anode 15 ... Cathode 16, 17 ... Gas diffusion layer 20, 21 ... Separator 20P, 21P ... Single-cell flow path

Claims (3)

A method for producing a membrane electrode assembly used in a fuel cell,
A catalyst layer forming step of forming a catalyst layer by applying a mixed ink in which water and an organic solvent are mixed, a catalyst ink in which catalyst-carrying conductive particles and an ionomer are mixed, to the electrolyte membrane;
The catalyst layer forming step, the catalyst ink upon grant with 30 seconds the electrolyte membrane, based on the weight of the electrolyte membrane before the absorption, 30% or more 60% or less by weight of the catalyst A method for producing a membrane electrode assembly, comprising: a water ratio adjusting step of adjusting a water ratio, which is a ratio of a weight of the mixed water to a weight of the mixed solvent, so that the mixed solvent in the ink is absorbed by the electrolyte membrane . It is a manufacturing method of the membrane electrode assembly according to claim 1,
Before Kisui ratio adjusting step, 3 0% or more 40% or less of As the mixed solvent is absorbed in the weight, manufacturing method of the membrane electrode assembly to adjust the pre Kisui ratio.   The method for producing a membrane / electrode assembly according to claim 1 or 2, wherein the organic solvent is ethanol.