JP5071646B2 - Fuel cell electrode paste, electrode and membrane electrode assembly, and fuel cell system manufacturing method. - Google Patents

Description

  The present invention relates to an electrode paste for a fuel cell, an electrode and a membrane electrode assembly, and a method for manufacturing a fuel cell system.

  Conventionally, a fuel cell system using a membrane electrode assembly (MEA) 90 as shown in FIG. 13 is known. The membrane electrode assembly 90 includes an electrolyte membrane 91 made of a solid polymer membrane such as Nafion (registered trademark, Nafion (manufactured by Dupon)), and a cathode electrode joined to one surface of the electrolyte membrane 91 and supplied with air. 93 and an anode 92 that is joined to the other surface of the electrolyte membrane 91 and is supplied with a fuel such as hydrogen.

  The cathode electrode 93 includes a gas-permeable base material such as carbon cloth, carbon paper, carbon felt, and the like, and a cathode catalyst layer 93a formed on one surface of the base material. A portion of the cathode electrode 93 other than the cathode catalyst layer 93a is formed of a base material, which is a cathode diffusion layer 93b that diffuses air to the cathode catalyst layer 93a on the non-electrolyte side.

  The anode 92 also includes the base material and an anode catalyst layer 92a formed on one surface of the base material. The portion other than the anode catalyst layer 92a in the anode electrode 92 is also formed of a base material, and this is an anode diffusion layer 92b that diffuses air to the anode catalyst layer 92a on the non-electrolyte side.

  The membrane electrode assembly 90 is sandwiched between separators (not shown) to form a fuel cell as a minimum power generation unit, and a large number of these cells are stacked to form a fuel cell stack. Air is supplied to the cathode catalyst layer 93a by air supply means, and hydrogen or the like is supplied to the anode catalyst layer 92a by hydrogen supply means or the like. Thus, the fuel cell system is configured.

In the membrane electrode assembly 90, hydrogen ions (H ⁺ ; protons) and electrons are generated from the fuel by an electrochemical reaction in the anode catalyst layer 92a. Protons move in the electrolyte membrane 91 toward the cathode catalyst layer 93a in the form of H ₃ O ⁺ accompanied by water molecules. The electrons flow through the load connected to the fuel cell system and flow into the cathode catalyst layer 93a. On the other hand, in the cathode catalyst layer 93a, water is generated from oxygen, protons and electrons contained in the air. The fuel cell system can continuously generate an electromotive force by continuously performing such an electrochemical reaction.

  The characteristics required for the anode catalyst layer 92a and the cathode catalyst layer 93a are as follows: (1) the oxidizing gas and fuel gas can be diffused; and (2) the proton generated by the electrochemical reaction is transferred to the solid electrolyte membrane. And (3) good electron conductivity for extracting current to the outside. And in order to satisfy these characteristics, each electrode paste is applied to a base material such as carbon cloth by mixing a catalyst-carrying carbon having electron conductivity and a polymer solid electrolyte having proton conductivity. A catalyst layer was formed. For example, as shown in FIG. 14, Non-Patent Document 1 discloses a method in which a polymer electrolyte solution is poured into catalyst-supporting carbon and stirred with ultrasonic waves to form an electrode paste.

However, in the catalyst layer formed using the electrode paste manufactured by such a method, the orientation of the hydrophilic functional group present in the polymer solid electrolyte is not taken into consideration. Many hydrophilic functional groups will be present on the pore side. For this reason, since the pore wall becomes hydrophilic and easily wets with water, the water easily accumulates in the pores, and the accumulated water inhibits gas diffusion through the pores.
Further, since a hydrophilic path that is oriented toward the catalyst-carrying carbon and does not communicate is not formed, water generated in the cathode catalyst layer is difficult to back-diffuse to the solid electrolyte membrane side. For this reason, water stays in the cathode catalyst layer and becomes a factor that inhibits gas diffusion.
Furthermore, the catalyst-carrying carbon and the polymer solid electrolyte tend to be large aggregates (agglomerates), and the catalyst-carrying carbon inside the agglomerates cannot contribute to the electrode reaction, which is wasted.

  The inventors have already developed a method for producing an electrode paste for a fuel cell that solves these problems (Patent Documents 1 and 2). In this manufacturing method, as a first step, after containing a mixture containing an infinite number of catalyst-supporting carbon and water in the chamber, the chamber is rotated to revolve the chamber while applying centrifugal force to the mixture. The mixture is stirred by its own weight. As a result, air can be forced out of the surface of each catalyst-supporting carbon, and the surface can be covered with water. At this time, since foreign substances such as balls and propellers are not used for imparting centrifugal force and stirring, contact between the catalyst-supporting carbons is hardly hindered.

  And as a 2nd process, the solution of a polymer electrolyte is mixed with the mixture obtained at the 1st process, and the paste for electrodes is obtained. At this time, since each catalyst-supporting carbon has wettability to water, the polymer electrolyte orients proton exchange groups of the polymer electrolyte on the catalyst-supporting carbon side. And the paste for electrodes of this invention in which the hydrophilic layer which mutually continues with water was formed between each catalyst support carbon and polymer electrolyte which mutually contact is obtained.

In the electrode paste thus obtained, as shown in FIG. 15, hydrophilic layers 102 that are continuous with each other are formed by water between the catalyst-supporting carbon 100 and the polymer electrolyte 101 that are in contact with each other. For this reason, if an anode electrode or a cathode electrode of a fuel cell is manufactured using this electrode paste, protons easily move through the hydrophilic layer in the anode electrode or the cathode electrode. In addition, since the proton exchange group is oriented on the hydrophilic layer side of the polymer electrolyte, the hydrophilic layer is effectively used for proton transfer.
Further, since the hydrophobic portion of the polymer electrolyte is oriented toward the pores and the pores become hydrophobic, it is difficult for water to accumulate, preventing bleeding, and inhibiting gas diffusion. For this reason, in the fuel cell system, H ₃ O moves well at the anode electrode, the electrolyte membrane, and the cathode electrode of the MEA, and a high output can be obtained while being lightly humidified or not humidified.

  Conventionally, Patent Documents 3 to 8 disclose techniques related to the present invention.

JP 2006-140061 A JP 2006-140062 JP Japanese Patent Laid-Open No. 2004-199915 JP 2004-185900 A JP 2003-59505 A JP 2002-324557 A JP 2003-7308 A JP 2002-134120 A Handbook of Fuel Cells (John Wiley & Sons Lid. (2003)) vol.3 p538

  However, the electrode pastes described in Patent Documents 1 and 2 still have room for improvement in that the catalyst-supporting carbon and the polymer solid electrolyte form large aggregates (agglomerates). There was room for further enhancing the orientation of the group toward the hydrophilic layer.

  The present invention has been made in view of the above-described conventional situation, and the catalyst-supporting carbon and the polymer solid electrolyte are unlikely to become large aggregates (agglomerates), and the proton exchange group of the polymer electrolyte is strongly applied to the hydrophilic layer side. The problem to be solved is to enable the production of a fuel cell electrode paste that is oriented, excellent in gas diffusivity and proton conductivity of the catalyst layer, and capable of obtaining high output while being lightly humidified or non-humidified. .

The fuel cell electrode paste manufacturing method according to the present invention includes an infinite number of catalyst-supporting carbons obtained by supporting a catalyst metal on carbon powder, and each of the catalyst-supporting carbons bonded to each other and a gas-permeable substrate. A method for producing an electrode paste for a fuel cell to obtain a paste for an electrode by mixing a polymer electrolyte solution for
After containing a countless mixture of the catalyst-supporting carbon and water in the chamber, the mixture is rotated by rotating the chamber while revolving the chamber and rotating the chamber. A first step of stirring to obtain a first intermediate;
A second step of obtaining a porous second intermediate by evaporating ice other than the surface adsorbed water of the first intermediate by freeze-drying the first intermediate under reduced pressure;
A third step of obtaining a paste for an electrode by mixing the polymer electrolyte solution with the second intermediate while maintaining a reduced pressure state.

  In the method for producing an electrode paste for a fuel cell of the present invention, first, as a first step, a mixture containing an infinite number of the catalyst-supporting carbon and water is contained in a chamber, and then the mixture is revolved by revolving the chamber. The mixture is stirred by its own weight by rotating the chamber while applying centrifugal force to obtain a first intermediate. As a result, air can be forced out of the surface of each catalyst-supporting carbon, and the surface can be covered with water. At this time, since foreign substances such as balls and propellers are not used for imparting centrifugal force and stirring, contact between the catalyst-supporting carbons is hardly hindered.

  In the second step, the first intermediate is freeze-dried under reduced pressure. Thereby, excess water other than the surface adsorbed water of the first intermediate is dissipated as water vapor by sublimation from the ice state, secondary aggregation is suppressed, and a porous second intermediate is obtained. Since the surface adsorbed water of the second intermediate still remains, it is a hydrophilic surface.

  A polymer electrolyte solution is mixed with the second intermediate thus obtained while maintaining a reduced pressure state (third step). Here, since the proton exchange group of the polymer electrolyte has hydrophilicity, the proton exchange group of the polymer electrolyte is highly adsorbed on the surface of the particles of the second intermediate that is adsorbed on the surface and becomes hydrophilic. It adheres in an oriented state. Thus, the electrode paste of the present invention is manufactured.

  In the electrode paste obtained by the present invention, hydrophilic layers that are continuous with each other are formed by water between the catalyst-supporting carbon and the polymer electrolyte that are in contact with each other. For this reason, if an anode electrode or a cathode electrode of a fuel cell is manufactured using this electrode paste, protons easily move through the hydrophilic layer in the anode electrode or the cathode electrode. Moreover, since the proton exchange group is highly oriented on the hydrophilic layer side of the polymer electrolyte, the hydrophilic layer is effectively used for proton transfer. Furthermore, since the catalyst-carrying carbon and the polymer solid electrolyte do not form large aggregates (agglomerates), the proportion of the catalyst-carrying carbon that cannot contribute to the electrode reaction is reduced, and gas diffusion is hardly inhibited. Fuel cell electrodes can be formed. Therefore, if the fuel cell is constituted by the fuel cell electrode paste of the present invention, a high output can be obtained while being lightly humidified or non-humidified.

  In addition, the above Patent Documents 3 to 8 describe the hydrophilization of catalyst-supported carbon. However, the fuel cell system obtained by using the electrode paste disclosed therein cannot achieve the same effect as the fuel cell system obtained by using the electrode paste of the present invention. The anode electrode and the cathode electrode obtained by the electrode paste disclosed in these do not contain water locally, in these, contact between each catalyst-supported carbon is inhibited, the polymer electrolyte and each The inventors infer that the hydrophilic layers that are continuous with each other are not formed between the catalyst-supporting carbon and water. Moreover, in these, although the polymer electrolyte is partially oriented, the inventors infer that they are not formed continuously. Furthermore, since the electrode paste of the present invention does not require expensive plasma irradiation for hydrophilizing each catalyst-supporting carbon, it contributes to lowering the fuel cell system.

The method for producing an electrode of a fuel cell of the present invention comprises a base material having gas permeability and a catalyst layer formed on one surface of the base material, and the catalyst layer carries a catalyst metal on carbon powder. A fuel cell electrode manufacturing method comprising: a myriad of catalyst-supporting carbons; and a polymer electrolyte that binds the catalyst-supporting carbons to each other and the base material,
The electrode paste is applied to one surface of the substrate to obtain an electrode. For the application, means such as printing can be employed.

  In the electrode thus obtained, hydrophilic layers that are continuous with each other are formed by water between the catalyst-supporting carbon and the polymer electrolyte that are in contact with each other. For this reason, protons tend to move in the anode and cathode by the hydrophilic layer. In addition, since the polymer electrolyte has proton exchange groups highly oriented on the hydrophilic layer side, the hydrophilic layer is effectively used for proton transfer. Furthermore, since the catalyst-carrying carbon and the polymer solid electrolyte do not form a large aggregate (agglomerate), the ratio of the catalyst-carrying carbon that cannot contribute to the electrode reaction is reduced, and gas diffusion is hardly inhibited.

  The fuel cell membrane electrode assembly manufacturing method of the present invention includes an electrolyte layer, a cathode electrode joined to one surface of the electrolyte layer and supplied with air, and a fuel joined to the other surface of the electrolyte layer and supplied with fuel. In the method of manufacturing a fuel cell membrane electrode assembly having an anode electrode, the electrode is used as at least one of the cathode electrode and the anode electrode.

  In the membrane electrode assembly thus obtained, hydrophilic layers that are continuous with each other are formed by water between the catalyst-supporting carbon and the polymer electrolyte that are in contact with each other. For this reason, protons tend to move in the anode and cathode by the hydrophilic layer. In addition, since the polymer electrolyte has proton exchange groups highly oriented on the hydrophilic layer side, the hydrophilic layer is effectively used for proton transfer. Furthermore, since the catalyst-carrying carbon and the polymer solid electrolyte do not form a large aggregate (agglomerate), the ratio of the catalyst-carrying carbon that cannot contribute to the electrode reaction is reduced, and gas diffusion is hardly inhibited.

  At least one of the cathode electrode and the anode electrode is preferably formed on the other surface of the substrate and has a diffusion layer for diffusing air or fuel. As a result, the fuel cell system easily causes a cell reaction, and a high output can be obtained.

  A method of manufacturing a fuel cell system according to the present invention includes a membrane electrode assembly, an air supply unit that supplies air to the cathode electrode, and a fuel supply unit that supplies the fuel to the anode electrode. In the manufacturing method, the membrane electrode assembly is used.

  In the fuel cell system obtained in this way, water moves well at the anode electrode, the electrolyte membrane, and the cathode electrode, and a high output is obtained while being lightly humidified or not humidified.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

Example 1
<Manufacture of electrode paste>
The electrode paste used in the fuel cell was produced according to the flowchart shown in FIG.
First, in Step S1, a commercially available aggregate made of a myriad of catalyst-supported carbons was prepared. Each catalyst-supporting carbon is obtained by supporting 60% by weight of a catalyst metal composed of Pt on a substantially spherical carbon powder. In Step S2, 1 g of this catalyst-supporting carbon was put in a beaker, placed in a vacuum drying chamber at 150 ° C. for 1 hour, and vacuum-dried. The reason why the catalyst-carrying carbon is vacuum-dried is to remove the impurities on the surface of each catalyst-carrying carbon as much as possible and to bring it close to hydrophilicity. At this time, the aggregate was not crushed so as not to inhibit the contact between the catalyst-carrying carbons.

Thereafter, in Step S3, 12 g of water was added to the vacuum-dried catalyst-carrying carbon, and the mixture was centrifuged by the following method to obtain a first intermediate. That is, first, a rotation / revolution centrifugal stirrer (manufactured by Keyence Corporation, trade name “Hybrid Mixer HM-500”) having a chamber 1000 shown in FIG. 2 was prepared. The chamber 100 includes a container 10a, the container 10a made of a lid 10b which seals the, to the center point O ₁ about, the axis P of the self is revolved at a high speed to draw a cone extending from the central point O ₁ And can be rotated around the axis P at high speed (see FIG. 3). In this chamber 10, a mixture 20 containing the aggregate 11 and water 12 equivalent to eight times the aggregate 11 was accommodated. Thereafter, the chamber 10 was rotated by revolving the chamber 10 while the centrifugal force was applied to the mixture 20, and the chamber 10 was rotated by its own weight. In this way, air is forcibly expelled from the surface of each catalyst-carrying carbon, and the gaps between the carbon powders are also filled with water. As shown in FIG. Product 41 was obtained. At this time, since foreign substances such as balls and propellers are not used for applying centrifugal force and stirring, contact between the catalyst-supporting carbons 31 is not hindered.

  And in step S4 shown in FIG. 1, freeze-drying was performed. The freeze-drying was performed by a freeze-drying apparatus 60 shown in FIG. The freeze-drying device 60 is provided with a freeze-drying chamber 62 accommodated in a freezer 61, and a suction pipe 63 is connected to the freeze-drying chamber 62, and a rotary pump 65 is connected via a liquid nitrogen trap 64. It is connected. In the freeze-drying chamber 62, a refrigerant pipe 62b is wound around a chamber body 62a having a substantially cylindrical container shape. The refrigerant pipe 62b is connected to a refrigerant circulation device (not shown), and the refrigerant below freezing point circulates in the refrigerant pipe 62b. It is like that. A sample tube 62c is accommodated in the chamber body 62a, and is installed so that the thermocouple 62d is in contact with the side wall of the sample tube 62c. The thermocouple 62d is connected to a temperature control device (not shown) so that the refrigerant circulation device can be controlled so that the sample tube 62c has a set temperature. Further, a PTFE tube 62f for introducing a Nafion solution into the sample tube 62c from the outside is attached to the lid 62e of the chamber body 62a.

  Freeze drying was performed according to the following procedure. First, the lid 62e of the chamber body 62a is removed, the sample tube 62c is taken out, and the above-described first intermediate 41 is put into the sample tube 62c. Then, the sample tube 62c is placed in liquid nitrogen, and the first intermediate 41 is flash-frozen. Then, the sample tube 62c is accommodated in the chamber body 62a again, and the lid 62e is closed. Here, the first intermediate 41 is instantly frozen because the catalyst-carrying carbon 31 is uniformly in the matrix of the ice 70 by freezing before the catalyst-carrying carbon contained in the first intermediate 41 is precipitated. (See FIG. 6A). Then, in order to keep the first intermediate 41 in the sample tube 62c frozen, the control device circulates the refrigerant in the refrigerant tube 62b while controlling the temperature of the sample tube 62c to −5 ° C. Then, after the temperature of the sample tube 62c reached −5 ° C., the rotary pump 65 was driven, and lyophilization was performed for 4 hours under a pressure of 30 Pa, whereby the second intermediate 42 was obtained. By this step, as shown in FIG. 6B, the matrix ice 70 gradually sublimates and is captured by the liquid nitrogen trap 64 (see FIG. 5). However, from the change in weight before and after lyophilization, it was found that 0.5 g of water was still present immediately after lyophilization for 4 hours. This is considered that the surface adsorbed water 32 adsorbed on the surface of the catalyst-carrying carbon 31 remains as it is without sublimation, and the surface of the catalyst-carrying carbon 31 is covered with the surface adsorbed water 32 (see FIG. 6 (b)) indicating that the hydrophilicity is maintained.

Further, in step S5 shown in FIG. 1, the pressure of the freeze-drying chamber 62 shown in FIG. 5 is kept at 30 Pa, the temperature of the sample tube 62c is set to −20 ° C., and Nafion (registered trademark) is externally passed through the PTFE tube 62f. 7 g of an ethanol solution (5 wt%) was introduced. Here, since the water other than the surface adsorbed water 32 is sublimated in the second intermediate 42 and is porous, the Nafion solution easily penetrates into the porous space. Further, since the second intermediate 42 is rendered hydrophilic by the presence of the surface adsorbed water 32, the Nafion layer 33 is formed in a state where the sulfone group (SO ³⁻ ) of Nafion is strongly oriented to the surface adsorbed water 32 side. (See FIG. 7). Thus, an electrode paste was obtained.

<Manufacture of fuel cell single layer cells>
A fuel cell single layer cell was manufactured using the electrode paste of Example 1 and evaluated.
The electrode paste of Example 1 obtained by the above method is printed on the surface of the carbon cloth so that the amount of Pt supported is 0.4 mg / cm ² and dried. Thus, the diffusion layer 1 of Example 1 was obtained. Instead of printing on the diffusion layer to form the reaction layer, the catalyst paste is printed on a polytetrafluoroethylene sheet, dried, and peeled to produce a self-supporting reaction layer film. The reaction layer may be formed by thermocompression bonding with a diffusion layer.

  A fuel cell single-layer cell shown in FIG. 8 was prepared using the diffusion layer 1 prepared as described above. That is, two diffusion layers 1 are prepared, and the reaction layer 3 side is sandwiched between both sides of a polymer electrolyte membrane 2 made of Nafion (registered trademark), and pressure bonded by hot pressing. Further, separators 4a and 4b serving as oxygen and hydrogen gas supply passages are pressed against the outside by a mounting jig (not shown). In this way, the fuel cell single-layer cell 20 is manufactured, and the fuel cell single-layer cell 20 is further laminated to complete the fuel cell stack.

(Comparative Example 1)
In Comparative Example 1, the catalyst-supported carbon 31 used in Example 1 was used as the electrode paste for the fuel cell, and the amount of Nafion solution added was the same, and the mixture was ultrasonically stirred. The manufacturing method of the fuel cell single-layer cell is the same as that of Example 1, and the description thereof is omitted.

<Evaluation>
About the catalyst layer which concerns on the said Example 1 and the comparative example 1, the pore distribution by a nitrogen gas adsorption method was measured. In addition, the power generation performance test was performed on the fuel cell single-layer cells according to Example 1 and Comparative Example 1.

  As a result, as for the pore distribution, as shown in FIG. 9, it was found that Example 1 had a larger differential pore volume and higher porosity than Comparative Example 1. For this reason, in the catalyst layer according to Example 1, the water accumulated by the electrolytic reaction and the water transfer is quickly eliminated, and it is difficult to be immersed in water. For this reason, it has been found that the output is increased because the bleeding is prevented and the gas diffusion supply is performed quickly.

  Also, as shown in FIG. 10, the power generation performance when the temperature of the air sent to the cathode side is 50 ° C. and the humidity is 100%, the single-layer fuel cell according to Example 1 is the single-cell fuel cell according to Comparative Example 1. It can be seen that even at a large current, the voltage drop is small compared to. Furthermore, as shown in FIG. 11, the temperature of the air sent to the cathode side is 70 ° C., and the power generation performance in the non-humidified state is substantially the same in the continuous operation of about 2 hours in the fuel cell unit cell according to Comparative Example 1. While the voltage decreased, in the single fuel cell according to Example 1, the cell voltage was substantially constant during the long-term operation up to 9 hours and hardly decreased.

<Manufacture of MEA>
Using the electrode paste of Example 1, the MEA can be manufactured as follows. First, carbon cloth is prepared as a base material having gas permeability, and a diffusion layer having a water repellent layer made of a mixture of carbon black and PTFE is formed on both sides. Thereafter, the cathode catalyst layer and the anode catalyst layer are printed using the electrode paste. Then, the substrate after printing is dried, and the alcohol and water in the solution are evaporated to obtain a cathode electrode and an anode electrode.

  Then, the solid polymer electrolyte membrane such as Nafion is cut into a certain size. In addition, after the appearance of the cathode and anode is inspected, the cathode and anode are also cut to a certain size.

  Thereafter, the anode electrode, the polymer solid electrolyte membrane, and the cathode electrode are stacked in this order, and hot pressed at 140 ° C. and a pressure of 60 kgf. In this way, MEA is obtained. Further, the MEA is cut in size and stacked to complete the stack.

  In addition, the method for producing MEA using the electrode paste of the present invention can be applied to other applications. For example, first, an electrode paste is uniformly applied to a predetermined area on a transfer film for an anode and a cathode. Thereafter, each paste is dried to form a catalyst layer on the transfer film. Then, a transfer film is disposed so as to sandwich the membrane so that each catalyst layer faces the polymer electrolyte membrane, and the catalyst layer is transferred to the membrane by hot pressing. It is also possible to produce an MEA in this way.

  In addition, a catalyst layer is formed on both surfaces of the polymer electrolyte membrane by a spray method or a coating method using an electrode paste. And it arrange | positions so that the base material for electrodes may contact the surface of each catalyst layer, and it hot-presses. It is also possible to produce an MEA in this way.

<Fuel cell system>
The following fuel cell system can be constructed using the MEA thus obtained. In this fuel cell system, a plurality of cells 70 shown in FIG. 12 are used. Each cell 70 includes a membrane electrode assembly (MEA) 71 and a pair of separators 72.

  The MEA 71 has an electrolyte membrane 73 made of Nafion, an anode electrode 74 integrally joined to one surface of the electrolyte membrane 73, and a cathode electrode 75 joined integrally to the other surface of the electrolyte membrane 73.

The anode electrode 74 includes an anode catalyst layer 74a provided on the electrolyte membrane 73 side and an anode diffusion layer 74b joined to the non-electrolyte membrane side of the anode catalyst layer 74a and diffusing hydrogen into the anode catalyst layer 74a.
The cathode electrode 75 includes a cathode catalyst layer 75a provided on the electrolyte membrane 73 side and a cathode diffusion layer 75b that is bonded to the non-electrolyte membrane side of the cathode catalyst layer 75a and diffuses air into the cathode catalyst layer 75a.

  Each separator 72 is formed with a hydrogen chamber 76 for supplying hydrogen to the anode electrode 74 on one surface side and an air chamber 77 for supplying air to the cathode electrode 75 on the other surface side.

  Each cell 70 is formed by laminating an MEA 71 and a pair of separators 72 so that the hydrogen chamber 76 faces the anode electrode 74 side and the air chamber 77 faces the cathode electrode 75 side. A stack is formed by sequentially stacking the MEA 71 and the separator 72. Further, the separator 72 common to the anode electrode 74 side and the cathode electrode 75 side is employed. Note that only the hydrogen chamber 76 or the air chamber 77 is formed in the separators 72 at both ends of the stack.

  A hydrogen cylinder 78 communicating with the hydrogen chamber 76 of each cell 70 via a valve (not shown) and a blower 79 communicating with the air chamber 77 of each cell 70 are connected to the stack. The hydrogen cylinder 78 and the hydrogen chamber 76 of the separator 72 are hydrogen supply means for supplying hydrogen to the anode catalyst layer 74a. The air chamber 77 of the blower 79 and the separator 72 is air supply means for supplying air to the cathode catalyst layer 75a.

  In this fuel cell system, the cathode catalyst layer 75a and the anode catalyst layer 74a of the MEA 71 are formed by using the electrode paste of Example 1, so that the bleeding phenomenon hardly occurs and gas diffusion is performed quickly. In addition, the cell voltage is unlikely to decrease even in non-humidified continuous operation.

  The present invention is not limited to the description of the embodiments of the invention. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

  The present invention can be used for a moving power source for an electric vehicle or the like, or a stationary power source.

It is a flowchart which shows the manufacturing method of the paste for electrodes of the fuel cell of an Example. It is the schematic diagram of the chamber of the autorotation / revolution type centrifugal stirrer used in the Example. It is a schematic diagram which shows the rotation state of the chamber of the autorotation / revolution type centrifugal stirrer used in the Example. It is an expansion schematic diagram of a 1st intermediate. It is a schematic diagram of the freeze-drying apparatus used in the Example. It is an expansion schematic diagram in each manufacture stage of the paste for electrodes. It is an expansion schematic diagram which shows a mode that the sulfone group of Nafion in a 2nd intermediate is strongly orientated to the surface adsorption water side. It is a schematic cross section of a fuel cell single layer cell. It is a graph which shows the pore distribution of a catalyst layer. It is the graph which measured the power generation performance in 50 degreeC and 100% humidification. It is the graph which measured the electric power generation performance in 70 degreeC and non-humidification. It is a schematic cross section which shows the cell of an Example. It is a schematic cross section which shows the conventional MEA. It is a figure which shows the manufacturing method of the conventional paste for electrodes. It is a model expanded sectional view of the catalyst layer using the paste for electrodes manufactured by the method described in patent documents 1.

Explanation of symbols

31 ... Catalyst-supporting carbon 41 ... First intermediate 42 ... Second intermediate 10 ... Chamber 50 ... Electrode paste 12 ... Water 92a, 93a ... Catalyst layer (92a ... Anode catalyst layer, 93a ... Cathode catalyst layer)
2, 13 ... Electrode (92 ... Anode electrode, 93 ... Cathode electrode)
DESCRIPTION OF SYMBOLS 11 ... Electrolyte membrane 10 ... Membrane electrode assembly (MEA)
74b ... Anode diffusion layer 75b ... Cathode diffusion layer 79, 77 ... Air supply means, hydrogen supply means (79 ... Blower, 77 ... Air chamber)
78, 76 ... Fuel supply means (78 ... Hydrogen cylinder, 76 ... Hydrogen chamber

Claims (6)

An electrode is formed by mixing countless catalyst-supporting carbons obtained by supporting a catalyst metal on carbon powder and a polymer electrolyte solution for binding the catalyst-supporting carbons to each other and a gas-permeable substrate. A method for producing a paste for a fuel cell electrode to obtain a paste for a fuel cell,
After containing a countless mixture of the catalyst-supporting carbon and water in the chamber, the mixture is rotated by rotating the chamber while revolving the chamber and rotating the chamber. A first step of stirring to obtain a first intermediate;
A second step of obtaining a porous second intermediate by evaporating ice other than the surface adsorbed water of the first intermediate by freeze-drying the first intermediate under reduced pressure;
A method for producing an electrode paste for a fuel cell, comprising: a third step of mixing the polymer electrolyte solution with the second intermediate while maintaining a reduced pressure state to obtain an electrode paste.   A fuel cell electrode paste produced by the method of claim 1. A gas-permeable base material and a catalyst layer formed on one surface of the base material, the catalyst layer comprising countless catalyst-supporting carbons obtained by supporting a catalyst metal on carbon powder, and each of the catalysts A method for producing an electrode of a fuel cell comprising a polymer electrolyte that binds supported carbon to each other and binds to the substrate,
A method for producing an electrode for a fuel cell, wherein the electrode paste according to claim 2 is applied to one surface of the substrate to obtain an electrode. A membrane electrode assembly of a fuel cell having an electrolyte layer, a cathode electrode joined to one surface of the electrolyte layer and supplied with air, and an anode electrode joined to the other surface of the electrolyte layer and supplied with fuel In the manufacturing method,
A method for producing a membrane electrode assembly for a fuel cell, wherein the electrode according to claim 3 is used for at least one of the cathode electrode and the anode electrode.   5. The fuel cell membrane electrode assembly according to claim 4, wherein at least one of the cathode electrode and the anode electrode has a diffusion layer formed on the other surface of the base material and diffusing the air or the fuel. Body manufacturing method. In a manufacturing method of a fuel cell system, comprising: a membrane electrode assembly; an air supply means for supplying air to the cathode electrode; and a fuel supply means for supplying the fuel to the anode electrode.
A method for producing a fuel cell system, wherein the membrane electrode assembly according to claim 4 or 5 is used.

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