JP2006140062A - Fuel cell electrode paste, electrode and membrane electrode assembly, and fuel cell system manufacturing method - Google Patents

Abstract

A fuel cell system capable of producing a fuel cell system having a low running cost and hardly causing a decrease in output.
An infinite number of catalyst-supporting carbons obtained by supporting a catalyst metal on carbon powder, and a solution of a polymer electrolyte 82 for binding the catalyst-supporting carbons to each other and to a base material having gas permeability. The electrode paste 50 is obtained by mixing. At this time, after containing a mixture 40 containing innumerable catalyst-supporting carbon and water 32 in the chamber 35, the mixture is rotated by rotating the chamber 35 while rotating the chamber 35 and applying a centrifugal force to the mixture 40. 40 is stirred by its own weight to obtain intermediate 41. Thereafter, the solution is mixed with the intermediate 41 to obtain the electrode paste 50.
[Selection] Figure 4

Description

  The present invention relates to an electrode paste that constitutes a cathode electrode or an anode electrode of a fuel cell, a method for manufacturing these electrodes, a membrane electrode assembly, and a fuel cell system.

  Conventionally, a fuel cell system using a membrane electrode assembly (MEA) 90 as shown in FIG. 18 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.

  As shown in FIG. 19, the cathode catalyst layer 93a and the anode catalyst layer 92a are composed of an infinite number of catalyst-supporting carbons 81 formed by supporting a catalyst metal 81b such as platinum (Pt) on a substantially spherical carbon powder 81a, and each catalyst support. It includes a polymer electrolyte 82 that bonds carbon 81 to each other and bonds to a base material (not shown). As the polymer electrolyte 82, the same one as the electrolyte membrane 91 can be used.

  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.

  However, since protons generated in the anode catalyst layer 92a of the membrane electrode assembly 90 move in the electrolyte membrane 91 toward the cathode catalyst layer 93a with water molecules, the anode catalyst layer 92a and the electrolyte membrane 91 On the anode catalyst layer 92a side, the moisture content decreases and the anode catalyst layer 92a tends to dry, proton transfer is hindered, and the output of the fuel cell system tends to decrease.

  Further, in the cathode catalyst layer 93a, water is transferred by protons and produced water generated by the cell reaction, so that water becomes excessive and air diffusion is inhibited (hereinafter referred to as “flooding”). Battery system output tends to decrease.

  Therefore, conventionally, the problem of drying of the anode catalyst layer 92a and the electrolyte membrane 91 is solved by humidifying hydrogen gas with a humidifier, and the problem of the cathode catalyst layer 93a is made water repellent. We are trying to solve this problem by making it easy to discharge water to the outside. Conventionally, Patent Documents 1 to 6 disclose techniques related to the present invention.

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

  However, if the humidifier is provided on the anode electrode 92 side as described above, energy is consumed for its operation, and the running cost of the fuel cell system becomes high. In this case, more excess water exists on the cathode electrode 93 side, and there is a concern that the output is reduced due to flooding.

  The present invention has been made in view of the above-described conventional situation, and an object to be solved is to make it possible to manufacture a fuel cell system that is low in running cost and hardly causes a decrease in output.

  According to the inventor's knowledge, in a fuel cell, an electrolyte membrane such as a solid polymer membrane moves water well, but the anode and cathode electrodes joined to the electrolyte membrane move water well. I can't. As described above, since the anode electrode and the cathode electrode contain innumerable catalyst-supporting carbon and polymer electrolyte, the cause thereof is that they do not contain water locally, The inventors have inferred that contact between the catalyst-carrying carbons is hindered or that a hydrophilic layer continuous with each other is not formed by water between the polymer electrolyte and each catalyst-carrying carbon.

  That is, as shown in FIG. 19, in the conventional MEA 90, the electrolyte membrane 91 contains water 32 at least during use, and a hydrophilic layer 71 continuous in the thickness direction is formed in the electrolyte membrane 91. Is inferred. However, although the anode catalyst layer 92a and the cathode catalyst layer 93a contain water 32 at least during use, the contact between the catalyst-supporting carbons 81 is obstructed, or the polymer electrolyte 82 and the catalyst-supporting carbon 81 It is inferred that the hydrophilic layers 72 that are continuous with each other are not formed by the water 32 therebetween. For this reason, protons generated in the anode catalyst layer 92a are difficult to move in the anode catalyst layer 92a due to high ion resistance in the anode catalyst layer 92a, and ion resistance from the anode catalyst layer 92a into the electrolyte membrane 91 is also high. For this reason, it is difficult to move in the electrolyte membrane 91 and it is difficult to move in the cathode catalyst layer 93a because the ion resistance in the cathode catalyst layer 93a is high. In addition, the generated water generated in the cathode catalyst layer 93a accumulates on the cathode electrode 93 side, and it is easy for flooding to occur, and the anode electrode 92 and the electrolyte membrane 91 cause insufficient water to impede further proton conductivity. it is conceivable that.

  In addition, the inventor also inferred that the polymer electrolyte 82 has polarity and the anode electrode 92 and the cathode electrode 93, which cannot move water well, are not properly oriented.

  The inventor made a prototype of a fuel cell system that solved the problems caused by these inferences, and found that high output could be obtained even with light or no humidification. The present invention has thus been completed.

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 an intermediate;
A second step of mixing the solution with the intermediate to obtain an electrode paste.

  In the production method of the present invention, first, in the first step, after containing a mixture containing an infinite number of catalyst-supporting carbon and water in the chamber, the chamber is rotated while revolving the chamber while applying centrifugal force to the mixture. The mixture is stirred by its own weight to obtain an intermediate. Inventor's reasoning is that air can be forcibly removed from the surface of each catalyst-supporting carbon. Further, the surface of each catalyst-supporting carbon 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 an intermediate body, and the paste for electrodes is obtained. At this time, since each catalyst-supporting carbon has wettability to water, the polymer electrolyte orients ion reactive 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 continues mutually with water was formed between each catalyst support carbon and polymer electrolyte which contact mutually is obtained.

In the electrode paste thus obtained, hydrophilic layers that are mutually continuous with water are formed 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. In addition, since the polymer electrolyte has an ion reactive group oriented on the hydrophilic layer side, the hydrophilic layer is effectively used for proton transfer. Since the hydrophilic layer is considered to be composed of the hydroxyl group generated on the surface of each catalyst-supporting carbon and the ion reactive group of the polymer electrolyte, it seems to be in the form of a thin film. 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 is obtained while being lightly humidified or not humidified.

  Therefore, according to the present invention, it is possible to realize a fuel cell system that is low in running cost and hardly causes a decrease in output.

  In addition, the said patent documents 1-6 have description about the hydrophilization of catalyst carrying | support 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.

  In the second step, after the intermediate and the solution are accommodated in the chamber, the intermediate and the solution are centrifugally applied to the intermediate and the solution by rotating the chamber. It is preferable to stir to obtain an electrode paste. Inventor's reasoning thus allows air to be forcibly removed from intermediates and solutions. Also in this case, 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.

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.

  Since the hydrophilic layer is continuously formed in the catalyst layer in the electrode obtained in this way, protons easily move along this. In addition, since the polymer electrolyte orients the ion exchange groups of the polymer electrolyte on the hydrophilic layer side, the hydrophilic layer is effectively used for proton transfer. Therefore, in the fuel cell system, the ion-reactive group of the polymer electrolyte is on the catalyst-carrying carbon side between the catalyst-carrying carbon and the polymer electrolyte in the catalyst layer of the anode electrode, the electrolyte membrane, and the cathode electrode. Oriented to form a water channel, and the water channel is formed on the entire surface of the catalyst-carrying carbon, so the amount of water necessary for proton transfer is retained in the water channel and moves well in the water channel, and excess water is required Therefore, a high output can be obtained with light or no humidification.

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 a method for producing a membrane electrode assembly of a fuel cell having an anode electrode,
The electrode is used for at least one of the cathode electrode and the anode electrode.

  In the membrane / electrode assembly thus obtained, the hydrophilic layer is continuously formed in the catalyst layer, so that the protons easily move along this. In addition, since the polymer electrolyte orients the ion exchange groups of the polymer electrolyte on the hydrophilic layer side, the hydrophilic layer is effectively used for proton transfer. Therefore, in the fuel cell system, the ion-reactive group of the polymer electrolyte is on the catalyst-carrying carbon side between the catalyst-carrying carbon and the polymer electrolyte in the catalyst layer of the anode electrode, the electrolyte membrane, and the cathode electrode. Oriented to form a water channel, and the water channel is formed on the entire surface of the catalyst-carrying carbon, so the amount of water necessary for proton transfer is retained in the water channel and moves well in the water channel, and excess water is required Therefore, a high output can be obtained with light or no humidification.

  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. In the fuel cell system of the embodiment, a plurality of cells 1 shown in FIG. 13 are used. Each cell 1 includes a membrane electrode assembly (MEA) 10 and a pair of separators 20.

  The MEA 10 includes an electrolyte membrane 11 made of Nafion, an anode electrode 12 integrally joined to one surface of the electrolyte membrane 11, and a cathode electrode 13 joined integrally to the other surface of the electrolyte membrane 11.

  The anode electrode 12 includes an anode catalyst layer 12a provided on the electrolyte membrane 11 side, and an anode diffusion layer 12b joined to the non-electrolyte membrane side of the anode catalyst layer 12a and diffusing hydrogen into the anode catalyst layer 12a.

  The cathode 13 includes a cathode catalyst layer 13a provided on the electrolyte membrane 11 side, and a cathode diffusion layer 13b that is bonded to the non-electrolyte membrane side of the cathode catalyst layer 13a and diffuses air into the cathode catalyst layer 13a.

  Each separator 20 has a hydrogen chamber 21 for supplying hydrogen to the anode electrode 12 on one surface side and an air chamber 22 for supplying air to the cathode electrode 13 on the other surface side.

  Each cell 1 is formed by stacking the MEA 10 and a pair of separators 20 so that the hydrogen chamber 21 faces the anode electrode 12 side and the air chamber 22 faces the cathode electrode 13 side. A stack is formed by sequentially stacking the MEA 10 and the separator 20. Further, the separator 20 common to the anode electrode 12 side and the cathode electrode 13 side is employed. Note that only the hydrogen chamber 21 or the air chamber 22 is formed in the separators 20 at both ends of the stack.

  A hydrogen cylinder 2 communicating with the hydrogen chamber 21 of each cell 1 via a valve (not shown) and a blower 3 communicating with the air chamber 22 of each cell 1 are connected to the stack. The hydrogen cylinder 2 and the hydrogen chamber 21 of the separator 20 are hydrogen supply means for supplying hydrogen to the anode catalyst layer 12a. The air chamber 22 of the blower 3 and the separator 20 is an air supply means for supplying air to the cathode catalyst layer 13a.

  The fuel cell system of the embodiment is characterized by the cathode electrode 13 and the anode electrode 12 of the MEA 10. More specifically, the cathode catalyst layer 13a of the cathode electrode 13 and the anode catalyst layer 12a of the anode electrode 12 are characterized.

  The cathode catalyst layer 13a and the anode catalyst layer 12a are manufactured using a special electrode paste 50 schematically shown in FIG. This electrode paste 50 is manufactured by the following manufacturing method.

  First, as shown in FIG. 1, in Step S <b> 1, a commercially available aggregate 31 (see FIG. 4) made up of countless catalyst-carrying carbon 81 (see FIGS. 14 and 15) was prepared. As shown in FIGS. 14 and 15, each catalyst-carrying carbon 81 is obtained by carrying a catalytic metal 81b made of Pt on a substantially spherical carbon powder 81a. In step S2 shown in FIG. 1, the assembly 31 was placed in a vacuum drying chamber at 150 ° C. for 1 hour and vacuum dried. The reason why the catalyst-carrying carbon 81 is vacuum-dried is to remove impurities on the surface of each catalyst-carrying carbon 81 as much as possible and to make it close to hydrophilicity. At this time, the aggregate 31 was not crushed so as not to hinder the contact between the catalyst-carrying carbons 81.

  Thereafter, in step S3, an intermediate 41 is obtained. At this time, as shown in FIG. 5, the surface of each catalyst-carrying carbon 81 does not originally have a hydroxyl group, which is a hydrophilic group, and each catalyst-carrying carbon 81 has poor wettability. By simply adding it, water does not exist on the surface of each catalyst-supporting carbon 81. For this purpose, first, a rotation / revolution centrifugal stirrer (trade name “Hybrid Mixer HM-500” manufactured by Keyence Corporation) having a chamber 35 shown in FIG. 4 was prepared. The chamber 35 includes a container 35a and a lid 35b that seals the container 35a. The chamber 35 revolves around the center point O1 at a high speed and rotates around the axis P extending from the center point O1 at a high speed. To get. In this chamber 35, a mixture 40 containing the aggregate 31 and water 32 equivalent to eight times the aggregate 31 was accommodated. Then, the mixture 40 was stirred by its own weight by rotating the chamber 35 while applying centrifugal force to the mixture 40 by revolving the chamber 35. In this way, air is forcibly removed from the surface of each catalyst-supporting carbon 81, and the gap between the carbon powders 81a is 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 81 is not hindered.

  Then, in step S4 shown in FIG. 1, as shown in FIG. 4, an intermediate 41, a solution comprising Nafion as the polymer electrolyte 82, alcohol, and water are placed in the chamber 35 of the rotation / revolution centrifugal stirrer. After accommodating, the intermediate 35 and the solution were stirred by their own weight by rotating the chamber 35 while applying centrifugal force to the intermediate 41 and the solution by revolving the chamber 35. Thus, also in step S4, air is forcibly removed from the intermediate 41 and the solution. At this time, as shown in FIG. 7, each catalyst-carrying carbon 81 has wettability to water, so that the polymer electrolyte 82 is separated from the sulfone group of the polymer electrolyte 82 itself on the side of each catalyst-carrying carbon 81. The ion reactive group 82a is oriented. In addition, since foreign substances such as balls and propellers are not used for applying centrifugal force and stirring, the contact between the catalyst-supporting carbons 81 is hardly hindered. Thus, as shown in FIGS. 4 and 8, an electrode paste 50 is obtained in which hydrophilic layers 72 that are continuous with water 32 are formed between the catalyst-supporting carbon 81 and the polymer electrolyte 82 that are in contact with each other during power generation. It was.

  On the other hand, in step S5 shown in FIG. 2, a carbon cloth was produced as a base material having gas permeability. A diffusion layer having a carbon cloth as a base material and a water repellent layer made of a mixture of carbon black and PTFE on both sides was prepared. Thereafter, in step S6, the cathode catalyst layer 13a and the anode catalyst layer 12a were printed using the electrode paste 50. At this time, since the electrode paste 50 attached to the wall surface of the chamber 35 or the container 30 is expected to be poorly stirred, the electrode paste 50 existing as a supernatant in the chamber 35 or the container 30 was used. In step S7, the substrate after printing was dried, and the alcohol and water in the solution were evaporated to obtain the cathode 13 and the anode 12.

  FIG. 9 shows a micrograph in which the cross section of the cathode diffusion layer 13b or the anode diffusion layer 12b is magnified 50 times, and FIG. 10 shows a microphotograph at 50,000 times. 9 and 10, it can be seen that the cathode diffusion layer 13b or the anode diffusion layer 12b has innumerable fine holes. For this reason, it turns out that oxygen and hydrogen can easily pass through the cathode diffusion layer 13b and the anode diffusion layer 12b.

  In step S8, the electrolyte membrane 11 was cut to a certain size. In step S9, the appearance of the cathode electrode 13 and the anode electrode 12 was inspected, and in step S10, the cathode electrode 13 and the anode electrode 12 were also cut to a certain size.

  Thereafter, in step S11, the anode electrode 12, the electrolyte membrane 11 and the cathode electrode 13 were laminated in this order, and hot-pressed at 140 ° C. and a pressing force of 60 kgf. In this way, MEA10 was obtained. In step S12, the size of the MEA 10 is cut. In step S13, the MEA 10 is inspected. In step S14, the MEA 10 is completed.

  In addition, the method for producing MEA using the electrode paste of the present invention can be applied to other applications.

  For example, first, the electrode paste obtained in step S4 is uniformly applied to a predetermined area on the transfer film for the anode and the 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.

  FIG. 11 shows a photomicrograph in which the cross section of the MEA 10 is enlarged 20,000 times. In addition, FIG. 12 shows a microphotograph at a magnification of 1,000,000 of the cathode catalyst layer 13a or the anode catalyst layer 12a. Although it is not necessarily clear from FIGS. 11 and 12, if the cathode catalyst layer 13a of the cathode electrode 13 and the anode catalyst layer 12a of the anode electrode 12 are manufactured as described above, in these cases, FIG. It is inferred that the contact between the catalyst-supporting carbons 81 is maintained and a hydrophilic layer 72 is formed between the polymer electrolyte 82 and each of the catalyst-supporting carbons 81 by the water 32 as shown in FIG. The For this reason, protons generated in the anode catalyst layer 12a travel along the formed hydrophilic layer 72 and move in the anode catalyst layer 12a, so that the ionic resistance in the anode catalyst layer 12a is lowered, resulting in the anode catalyst layer. It is thought that it is easy to move in 12a. Then, as shown in FIG. 16, these protons are low in ionic resistance from the anode catalyst layer 12a into the electrolyte membrane 11 because they are in communication with the hydrophilic layer 72, and easily move into the electrolyte membrane 11. Since it moves through the hydrophilic layer 72 and moves in the cathode catalyst layer 13a, the ionic resistance in the cathode catalyst layer 13a is lowered, and as a result, it is considered that it is likely to move in the cathode catalyst layer 13a. Thus, it is considered that protons are likely to move in the anode 12 and the cathode 13 of the MEA 10.

  Furthermore, the produced water produced by the catalyst metal 81b of the cathode catalyst layer 13a quickly diffuses back to the anode electrode 12 side through the communicating hydrophilic layer 72. For this reason, in particular, dry-up of the electrolyte membrane 11 and the anode catalyst layer 12a during the low humidification operation can be effectively suppressed, and high power generation performance can be maintained.

  Moreover, in the cathode catalyst layer 13a and the anode catalyst layer 12a, as shown in FIG. 15, it is inferred that the polymer electrolyte 82 having polarity by the sulfone group is preferably oriented. For this reason, a sulfone group is directed on the surfaces of the carbon powder 81a and the catalyst metal 81b, and a hydrophilic group 72 is formed between the carbon powder 81a and the sulfone group. Thus, in this MEA 10, it is considered that the hydrophilic layer 72 is effectively utilized for proton movement.

Thus, the hydrophilic layer 72 is considered to be formed in a thin film shape by the hydroxyl group generated on the surface of each catalyst-supporting carbon 81 and the ion reactive group 82a of the polymer electrolyte 82 (PFF (Proton Film Flow) structure). ). For this reason, in this fuel cell system, H ₃ O moves well through the thin-film hydrophilic group 72 at the anode electrode 12, the electrolyte membrane 11, and the cathode electrode 13 of the MEA 10. Thus, since the hydrophilic layer 72 is formed in advance as a water passage, the supply of excess water from the outside to the anode electrode 12 and the electrolyte membrane 11 can be reduced, and flooding due to excess water is unlikely to occur. Therefore, a high output can be obtained while being lightly humidified or not humidified.

  The fuel cell system of the example and the fuel cell system of the comparative example were compared in the non-humidifying operation performance. The fuel cell system of the comparative example uses a conventional MEA90. In the conventional MEA 90, a catalyst-supported carbon powder is mixed with a solvent (water / ethylene glycol or the like), and then dispersed in an ion exchange resin and a solvent to prepare a paste. An electrode and a cathode electrode are produced, and an electrolyte membrane is sandwiched between the anode electrode and the cathode electrode. Other configurations of the fuel cell system of the comparative example are the same as those of the fuel cell system of the example.

The test conditions are an operating temperature of 70 ° C., a load of 0.7 A / cm ² , an air stoichiometric ratio of “4”, and a hydrogen stoichiometric ratio of “1.3”. The operating pressure of hydrogen and air was a counter flow system. The results are shown in FIG.

FIG. 17 shows the following in the fuel cell system of the example. First, the resistance is stable between 0.1 and 0.15 (Ω · cm ² ), which is the same level as that measured under full humidification conditions. On the other hand, with respect to the voltage, there is a characteristic that power is stably generated between 0.5 and 0.6 (V). These two results are evidence of a phenomenon in which the back diffusion of product water is good. On the other hand, it can be seen that the MEA 90 became inoperable immediately after operation due to lack of water.

  Therefore, according to the fuel cell system of the embodiment, a high output can be obtained even with light humidification or non-humidification, so that the running cost can be reduced.

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

3 is a flowchart showing a part of the manufacturing method according to the fuel cell system of the embodiment. 3 is a flowchart showing a part of the manufacturing method according to the fuel cell system of the embodiment. 3 is a flowchart showing a part of the manufacturing method according to the fuel cell system of the embodiment. It is the schematic of the chamber of the autorotation / revolution type centrifugal stirrer used with the manufacturing method of the Example. It is an expansion schematic diagram of a mixture. It is an expansion schematic diagram of an intermediate. It is an expansion schematic diagram which shows an intermediate body and a polymer electrolyte. It is an expansion schematic diagram of the paste for electrodes. It is the microscope picture which expanded the cross section of the cathode pole or the anode pole by 50 times. It is a 50,000 times microscope picture of the part of a cathode catalyst layer or an anode catalyst layer. It is the microscope picture which expanded the cross section of MEA 20,000 times. It is a 1 million times microscope picture of the part of a cathode catalyst layer or an anode catalyst layer. It is a schematic cross section which shows the cell of an Example. It is a model expanded sectional view which shows the cathode catalyst layer or anode catalyst layer of an Example. It is a schematic expanded sectional view of the XIV part of FIG. It is a model expanded sectional view which shows MEA of an Example. It is a graph which shows the non-humidification operation | movement performance in the fuel cell system of an Example and a comparative example concerning the test 1. FIG. It is a schematic cross section which shows MEA of the past and a comparative example. It is a model expanded sectional view which shows MEA of the past and a comparative example.

Explanation of symbols

81a ... carbon powder 81b ... catalyst metal 81 ... catalyst-supported carbon 82 ... polymer electrolyte 50 ... electrode paste 32 ... water 72 ... hydrophilic layer 12, 13 ... electrode (12 ... anode electrode, 13 ... cathode electrode)
12a, 13a ... catalyst layer (12a ... anode catalyst layer, 13a ... cathode catalyst layer)
DESCRIPTION OF SYMBOLS 11 ... Electrolyte membrane 10 ... Membrane electrode assembly (MEA)
12b ... Anode diffusion layer 13b ... Cathode diffusion layer 3, 22 ... Air supply means, hydrogen supply means (3 ... blower, 22 ... air chamber)
2, 21 ... Fuel supply means (2 ... Hydrogen cylinder, 21 ... Hydrogen chamber)

Claims (7)

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 an intermediate;
And a second step of mixing the solution with the intermediate to obtain an electrode paste. A method for producing an electrode paste for a fuel cell.   In the second step, after the intermediate and the solution are accommodated in the chamber, the chamber is revolved by rotating the chamber while revolving the chamber while applying centrifugal force to the intermediate and the solution. The method for producing an electrode paste for a fuel cell according to claim 1, wherein the intermediate and the solution are stirred by their own weight to obtain the electrode paste.   A paste for a fuel cell electrode produced by the method according to claim 1 or 2. 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 3 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 4 is used for at least one of the cathode electrode and the anode electrode.   6. The membrane electrode joint of a fuel cell according to claim 5, 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 5 or 6 is used.