JP2009187803A - Membrane electrode composite and fuel cell - Google Patents

Abstract

【選択図】図１A membrane electrode assembly that exhibits high power generation characteristics in a wide range of operation from low humidification to high humidification in which performance does not deteriorate even in a highly humid operating environment, and a fuel cell using the same.
A hydrocarbon polymer shown below (wherein, b represents a block copolymer, m and n represent the number of repeating units, and m ≧ 5 and n ≧ 5). A membrane electrode assembly 1 comprising catalyst electrode layers 3 and 4 disposed on both surfaces of the electrolyte membrane 2, wherein at least one of the catalyst electrode layers 3 and 4 contains a halogen element. Contains benzene sulfonic acid with or without.

[Selection] Figure 1

Description

  The present invention relates to a membrane electrode assembly used to form a fuel cell, particularly a polymer electrolyte fuel cell.

  A unit cell, which is the minimum power generation unit of a solid polymer electrolyte fuel cell (hereinafter sometimes simply referred to as a fuel cell), generally has a catalyst electrode layer (an anode side catalyst electrode layer and a cathode side catalyst) on both sides of the solid electrolyte membrane. There is a membrane electrode assembly (MEA) to which an electrode layer is bonded, and gas diffusion layers are arranged on both sides of the membrane electrode assembly. Furthermore, a separator having a gas flow path is arranged outside thereof, and the fuel gas and the oxidant gas supplied to the catalyst electrode layer of the membrane electrode composite are passed through the gas diffusion layer, It works to transmit the current obtained by power generation to the outside.

  In such a fuel cell, water is required for proton transfer from the anode side catalyst electrode layer to the electrolyte membrane and from the electrolyte membrane to the cathode side catalyst electrode layer. Therefore, generally, a method of humidifying the fuel gas and supplying water into the fuel cell is widely used. However, for example, when a fuel cell is used for a vehicle-mounted application or the like, a device that humidifies the fuel gas is a heavy object, which causes a reduction in fuel consumption, a reduction in vehicle space, an increase in cost, and the like.

  Further, since the temperature of the fuel battery cell is preferably about 40 to 80 ° C. from the viewpoint of reaction efficiency, usually, cooling water is introduced into the cell to suppress the temperature rise accompanying the battery reaction. However, cooling requires a heavy device such as a cooling fan and a radiator, which also causes a reduction in fuel consumption, a reduction in in-vehicle space, and an increase in cost.

Therefore, it is desirable to supply the fuel gas in a state where it is not necessary to perform “humidification” or “cooling” as described above, that is, in a state where the temperature is as high as possible and the humidity is as low as possible. In particular, in the case of automobiles, it is necessary to exhibit high power generation characteristics in a wide temperature range from near room temperature to a high temperature (80 to 100 ° C.). However, for example, a conventional fuel cell as disclosed in Patent Document 1 is designed on the assumption that flooding occurs in which water stays in the catalyst electrode layer during normal temperature operation. As described above, in general, the catalyst electrode layer and the gas diffusion are formed so that the generated water (H ₂ O) generated by the reaction of hydrogen (H ₂ ) and oxygen (O ₂ ) during operation can be efficiently drained. It aims at facilitating drainage of water, such as providing a water repellent layer between the layers. Therefore, it does not consider the operation of the fuel cell in a low moisture environment such as a high temperature / low humidity condition. Under high temperature / low humidity conditions, the membrane resistance increases as the electrolyte membrane dries, and the membrane and There has been a problem that the power generation performance of the fuel cell is lowered due to a decrease in proton conductivity in the catalyst electrode layer.

JP 2004-119102 A JP 2005-259513 A JP 2004-247286 A JP 2006-131800 A JP 2003-45437 A JP2003-238665A

  The present invention has been made in view of the above problems, and suppresses a decrease in power generation performance under a high-temperature / low-humidified operating environment, improves output, and decreases the performance even under a high-humidified operating environment. The main object of the present invention is to provide a membrane electrode assembly that exhibits high power generation characteristics in a wide range of operation from low humidification to high humidification, and a fuel cell using the same.

  In order to achieve the above object, in the present invention, a membrane electrode composite comprising an electrolyte membrane made of a hydrocarbon-based polymer represented by the following general formula (1) and catalyst electrode layers disposed on both surfaces of the electrolyte membrane The membrane electrode assembly is characterized in that at least one of the catalyst electrode layers contains benzenesulfonic acid represented by the following general formula (2).

(Wherein b represents a block copolymer, m and n represent the number of repeating units, and m ≧ 5, n ≧ 5, preferably 5 ≦ m ≦ 200, and 5 ≦ n ≦ 1000. .)

(In the formula, X is H or a halogen element.)

  According to the present invention, there is provided a membrane electrode composite comprising an electrolyte membrane made of a hydrocarbon-based polymer represented by the general formula (1) and a catalyst electrode layer disposed on both surfaces of the electrolyte membrane, wherein the catalyst When at least one of the electrode layers contains the benzenesulfonic acid represented by the general formula (2), the water retention of at least one of the catalyst electrode layers is improved. Therefore, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed, and a decrease in power generation performance under a high-temperature / low-humidity operating environment can be suppressed. Furthermore, since the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved by improving the affinity and adhesion between the electrolyte membrane and the catalyst electrode layer, a membrane electrode composite with improved output can be obtained. Obtainable. In addition, since the benzenesulfonic acid is a low molecular compound having a small size of one benzene ring, excess water can be discharged, flooding can be prevented, and reaction gas diffusibility can be improved. For this reason, power generation performance does not deteriorate even in a highly humid operating environment. Therefore, it is possible to obtain a membrane electrode assembly that exhibits high power generation characteristics in a wide range of operation from low humidification to high humidification.

  Further, in the present invention, at least the catalyst electrode layer containing the benzenesulfonic acid represented by the general formula (2) of the catalyst electrode layer contains a fluorocarbon electrolyte polymer. A membrane electrode assembly according to 1, is provided.

  According to the present invention, the catalyst electrode layer containing at least the benzenesulfonic acid represented by the general formula (2) in the catalyst electrode layer further contains a fluorocarbon electrolyte polymer, so that at least one of the catalysts can be obtained. The water retention of the electrode layer is further improved. Therefore, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed, and a decrease in power generation performance under a high-temperature / low-humidified operating environment can be more effectively suppressed.

  The present invention also provides a fuel cell using the membrane electrode assembly described above.

  According to the present invention, the water retention of the catalyst electrode layer is improved, so that drying of the electrolyte membrane and the catalyst electrode layer is suppressed to suppress a decrease in power generation performance under a high-temperature / low-humidity operating environment. By improving the affinity / adhesion between the membrane and the catalyst electrode layer, the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved, and by having the above membrane electrode composite with improved output, It is possible to obtain a fuel cell with improved output by suppressing a decrease in power generation performance under a high-temperature, low-humidified operating environment. In addition, since the benzenesulfonic acid in the catalyst electrode layer is a low-molecular compound having a small size of one benzene ring, it is possible to improve the discharge of excess water, prevent flooding, and improve the diffusibility of the reaction gas. In order to improve, by having the above membrane electrode assembly in which the power generation performance does not deteriorate even in a highly humid operating environment, a fuel cell exhibiting high power generation characteristics in a wide range of operation from low humidification to high humidification can be obtained.

  In the present invention, by improving the water retention of the catalyst electrode layer, it is possible to suppress drying of the electrolyte membrane and the catalyst electrode layer, it is possible to suppress a decrease in power generation performance in a high-temperature, low-humidity operating environment, Furthermore, since the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved by improving the affinity and adhesion between the electrolyte membrane and the catalyst electrode layer, a membrane electrode composite with improved output can be obtained. Obtainable. Further, since the gas diffusion is not hindered, there is an effect that it is possible to obtain a membrane electrode assembly exhibiting high power generation characteristics in a wide range of operation from low humidification to high humidification in which power generation performance does not deteriorate even in a highly humid operating environment.

  The membrane electrode assembly of the present invention will be described in detail below.

A. Membrane electrode composite First, the membrane electrode composite of the present invention will be described. The membrane electrode assembly of the present invention is a membrane electrode assembly comprising an electrolyte membrane made of a hydrocarbon-based polymer represented by the following general formula (1), and catalyst electrode layers disposed on both surfaces of the electrolyte membrane. At least one of the catalyst electrode layers contains a benzenesulfonic acid represented by the following general formula (2).

(Wherein b represents a block copolymer, m and n represent the number of repeating units, and m ≧ 5, n ≧ 5, preferably 5 ≦ m ≦ 200, and 5 ≦ n ≦ 1000. .)

(In the formula, X is H or a halogen element.)

  According to the present invention, there is provided a membrane electrode composite comprising an electrolyte membrane made of a hydrocarbon-based polymer represented by the general formula (1) and a catalyst electrode layer disposed on both surfaces of the electrolyte membrane, wherein the catalyst When at least one of the electrode layers contains the benzenesulfonic acid represented by the general formula (2), the water retention of the catalyst electrode layer is improved. Therefore, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed to prevent a decrease in power generation performance under a high temperature / low humid operating environment. Furthermore, since the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved by improving the affinity and adhesion between the electrolyte membrane and the catalyst electrode layer, a membrane electrode composite with improved output can be obtained. Obtainable. In addition, since the benzenesulfonic acid is a low molecular compound having a small size of one benzene ring, excess water can be discharged, flooding can be prevented, and reaction gas diffusibility can be improved. For this reason, power generation performance does not deteriorate even in a highly humid operating environment. Therefore, it is possible to obtain a membrane electrode assembly that exhibits high power generation characteristics in a wide range of operation from low humidification to high humidification.

  In the present invention, it is preferable that at least the catalyst electrode layer containing the benzenesulfonic acid represented by the general formula (2) in the catalyst electrode layer contains a fluorocarbon electrolyte polymer. When the catalyst electrode layer containing at least the benzenesulfonic acid represented by the general formula (2) in the catalyst electrode layer further contains a fluorocarbon electrolyte polymer, water retention of at least one of the catalyst electrode layers is improved. It is because it improves more. Therefore, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed, and a decrease in power generation performance under a high-temperature / low-humidified operating environment can be more effectively suppressed.

Hereinafter, the membrane electrode assembly of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an example of the configuration of the membrane electrode assembly of the present invention. As shown in FIG. 1, the membrane electrode assembly 1 has an electrolyte membrane 2 at its center and is sandwiched between an anode side catalyst electrode layer 3 and a cathode side catalyst electrode layer 4.
Hereinafter, the membrane electrode assembly according to the present invention will be described in detail for each constitution.

1. Electrolyte membrane The electrolyte membrane used in the present invention is composed of a hydrocarbon-based polymer represented by the following general formula (1).

(Wherein b represents a block copolymer, m and n represent the number of repeating units, and m ≧ 5, n ≧ 5, preferably 5 ≦ m ≦ 200, and 5 ≦ n ≦ 1000. .)
As such a hydrocarbon-based polymer, those described in JP 2007-177197 A can be suitably used.

  The hydrocarbon polymer represented by the general formula (1) is a block copolymer composed of two types of polymer molecular chains of a polyethersulfone represented by the following general formula (3) and a benzenesulfonic acid polymer. . In the present invention, when the electrolyte membrane has the benzenesulfonic acid polymer, a membrane electrode assembly with improved output can be obtained. This is because the later-described catalyst electrode layer contains benzenesulfonic acid, which is a proton conducting site of the electrolyte membrane, so that the affinity and adhesion between the electrolyte membrane and the later-described catalyst electrode layer are improved, and the electrolyte membrane This is presumably because the proton conductivity between the catalyst electrode layer and the catalyst electrode layer becomes good.

  The block copolymer represented by the general formula (1) has one or more of each of the two types of polymer molecular chains. Moreover, you may have 2 or more of each polymer molecular chain. As the molecular weight of the block copolymer, the number average molecular weight (Mn) in terms of polystyrene is usually preferably 5,000 to 1,000,000. More preferably, it is 15000-400000. This is because if the number average molecular weight (Mn) is 5000 or less, the film strength becomes weak, and if it is 1000000 or more, the film forming process may be difficult.

The ion exchange capacity of the hydrocarbon-based polymer represented by the general formula (1) is preferably 0.5 to 4.0 meq / g, and more preferably 1.0 to 3.0 meq / g. The ion exchange capacity can be determined by a known method, for example, by titration.
The ionic conductivity of the hydrocarbon polymer represented by the general formula (1) is, for example, 0.01 S / cm or more at 80 ° C. and 90% RH, and more preferably 0.1 S / cm or more. . The measuring method of ionic conductivity can be measured according to a known method.

  In addition, the thickness of the electrolyte membrane is not particularly limited, and a membrane having the same thickness as that of an electrolyte membrane used in a normal fuel cell can be used. Preferably, it exists in the range of 10-100 micrometers, More preferably, it exists in the range of 15-50 micrometers.

  The method for producing an electrolyte membrane used in the present invention is not particularly limited as long as it is generally used as a method for producing an electrolyte membrane. For example, the hydrocarbon system represented by the above formula (1) is used. Examples thereof include a method of forming a polymer film by a casting method or a melt extrusion method. Among these, it is preferable to use a solution casting method.

2. Catalyst electrode layer In the catalyst electrode layer used in the present invention, at least one of the anode side catalyst electrode layer and the cathode side catalyst electrode layer contains benzenesulfonic acid represented by the following general formula (2).

(In the formula, X is H or a halogen element.)
In the present invention, as the benzenesulfonic acid, for example, benzenesulfonic acid (manufactured by Aldrich) or the like can be used.

  In the present invention, the water retention of the catalyst electrode layer is improved by using the benzenesulfonic acid as an electrolyte material in the catalyst electrode layer. Therefore, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed to prevent a decrease in power generation performance under a high temperature / low humid operating environment. Furthermore, since the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved by improving the affinity and adhesion between the electrolyte membrane and the catalyst electrode layer, a membrane electrode composite with improved output can be obtained. Obtainable. In addition, since the benzenesulfonic acid is a low molecular compound having a small size of one benzene ring, excess water can be discharged, flooding can be prevented, and reaction gas diffusibility can be improved. For this reason, power generation performance does not deteriorate even in a highly humid operating environment. Therefore, it is possible to obtain a membrane electrode assembly that exhibits high power generation characteristics in a wide range of operation from low humidification to high humidification.

  In the above general formula (2), X is considered to be H or a halogen element, and among these, H is preferable.

  The addition amount of benzenesulfonic acid used in the present invention is in the range of 0.1 to 90% by mass, particularly in the range of 1 to 8% by mass, particularly 2 in terms of the ratio to the mass of electrolyte that is usually added in the catalyst electrode layer. It is preferable to be within a range of ˜6% by mass. This is because when the amount of benzenesulfonic acid is too large, the pores of the catalyst electrode layer are blocked, and there is a possibility of inhibiting gas reaction and proton transfer. On the other hand, if the amount of benzenesulfonic acid is too small, the moisture retention effect may not be obtained.

  The benzenesulfonic acid may be contained in at least one of the two catalyst electrode layers, but in the present invention, it is preferably contained in both of the two catalyst electrode layers.

  In the present invention, it is preferable that at least the catalyst electrode layer containing the benzenesulfonic acid represented by the general formula (2) in the catalyst electrode layer contains a fluorocarbon electrolyte polymer. When the catalyst electrode layer containing at least the benzenesulfonic acid represented by the general formula (2) in the catalyst electrode layer further contains a fluorocarbon electrolyte polymer, water retention of at least one of the catalyst electrode layers is improved. It is because it improves more. For this reason, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed, and a decrease in power generation performance under a high-temperature, low-humidity operating environment can be more effectively suppressed.

  Examples of the fluorocarbon electrolyte polymer solution (perfluorosulfonic acid resin) used in the present invention include Nafion (trade name, manufactured by DuPont), Flemion (trade name, manufactured by Asahi Glass), and Aciplex (trade name). , Manufactured by Asahi Kasei Co., Ltd.).

  The catalyst electrode layer is generally composed of a conductive material carrying a catalyst and an electrolyte material, and the catalyst is not particularly limited as long as it has a function as a catalyst. The same materials as those used for general fuel cells can be used. For example, platinum etc. can be mentioned.

  Further, the conductive material supporting the catalyst is not particularly limited as long as it has conductivity, and the same materials as those used in general fuel cells can be used. For example, carbon black or the like can be used.

  Further, the method for producing the catalyst electrode layer used in the present invention is not particularly limited as long as it is a method capable of obtaining a desired catalyst electrode layer. Specifically, the electrolyte material described above, and Examples thereof include a coating method in which a conductive material carrying a catalyst is dissolved and dispersed in a solvent to prepare a coating liquid, which is coated on an electrolyte membrane and dried.

3. Production method of membrane electrode composite The production method of the membrane electrode composite of the present invention is not particularly limited as long as it is a method capable of obtaining the above membrane electrode composite. After a catalyst such as powder is dispersed in water and an alcohol solvent (for viscosity adjustment), the above benzenesulfonic acid is added and stirred and dispersed, and then a fluorocarbon polymer electrolyte solution (perfluorosulfonic acid resin solution) is added. Add and stir and disperse to obtain electrode ink. Using the obtained electrode ink, apply directly to the electrolyte membrane described in “1. Electrolyte membrane”, apply to the diffusion layer, or apply to the Teflon (registered trademark) sheet, etc. It can be obtained by a production method such as a method of transferring by heat pressing.

B. Fuel Cell Next, the fuel cell of the present invention will be described. The fuel cell of the present invention is characterized by having the above membrane electrode assembly.

  According to the present invention, the water retention of the catalyst electrode layer is improved, so that drying of the electrolyte membrane and the catalyst electrode layer is suppressed to suppress a decrease in power generation performance under a high-temperature / low-humidity operating environment. By improving the affinity / adhesion between the membrane and the catalyst electrode layer, the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved, and by having the above membrane electrode composite with improved output, It is possible to obtain a fuel cell with improved output by suppressing a decrease in power generation performance under a high-temperature, low-humidified operating environment. In addition, since the benzenesulfonic acid in the catalyst electrode layer is a low-molecular compound having a small size of one benzene ring, it is possible to improve the discharge of excess water, prevent flooding, and improve the diffusibility of the reaction gas. In order to improve, by having the above membrane electrode assembly in which the power generation performance does not deteriorate even in a highly humid operating environment, a fuel cell exhibiting high power generation characteristics in a wide range of operation from low humidification to high humidification can be obtained.

  The membrane electrode assembly used in the present invention is the same as that described in the above-mentioned item “A. Membrane electrode composite”, and thus the description thereof is omitted here. The fuel cell which is the minimum unit of the fuel cell according to the present invention has a membrane electrode assembly composed of a catalyst electrode layer (anode side catalyst electrode layer and cathode side catalyst electrode layer) and a solid electrolyte membrane as described above. It is sandwiched between diffusion layers and further sandwiched between separators, and a plurality of such fuel cells are stacked to form a fuel cell stack. The gas diffusion layer and separator used at this time are not particularly limited, and those usually used can be used.

  In the present invention, the catalyst electrode layer includes at least one of the anode-side catalyst electrode layer and the cathode-side catalyst electrode layer containing the benzenesulfonic acid, but when either of them contains Is preferably contained in the anode catalyst electrode layer. This is because, when the operation is performed with low humidification, the generated water is generated on the cathode side, which is relatively difficult to dry. On the other hand, the generated water is not generated on the anode side, so that it is easily dried from the anode side.

  The method for producing a fuel cell of the present invention is not particularly limited as long as it is a method using a membrane electrode composite obtained by the above “A. Membrane electrode composite”. As an example of the manufacturing method of the fuel cell of the present invention, for example, a gas diffusion layer formed by molding carbon fibers or the like is installed outside the membrane electrode assembly, and a metal or carbon is further formed outside the gas diffusion layer. And a method of installing a separator made of metal.

  Although it does not specifically limit as a use of the fuel cell of this invention, For example, it can use as a fuel cell etc. for motor vehicles.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example]
(Membrane electrode composite production)
To 1 g of Pt / C catalyst (Pt loading 50 wt%) powder, 4 ml of 10 wt% solution of perfluorosulfonic acid resin solution (manufactured by Aldrich) was mixed so that carbon black: perfluorosulfonic acid resin = 1: 1. . To this, benzenesulfonic acid powder (manufactured by Aldrich) was added to 40 wt% with respect to the perfluorosulfonic acid resin. Next, 5 ml of ethanol was added and dispersed for a predetermined time using an ultrasonic cleaning device to prepare a catalyst ink.
An electrolyte membrane (IEC 2.2 meq / g, Mw 2.7 × 10 ⁵⁾ synthesized according to Example 1 in Japanese Patent Application Laid-Open No. 2007-177197 using the electrode ink obtained in the above-described catalyst electrode production. The catalyst electrode layer was produced on the electrolyte membrane by spray coating on a film thickness of 30 μm and drying to obtain a membrane electrode composite.

[Comparative example]
In the preparation of the membrane electrode assembly described above, a benzenesulfonic acid polymer represented by the following general formula (4), not benzenesulfonic acid powder (manufactured by Aldrich)

(In the formula, n represents the number of repeating units and is in the range of 2 to 10,000, and X is H or a halogen element.) Ink for electrodes was obtained in the same manner as in Examples. The obtained electrode ink was sprayed on the electrolyte membrane and dried to produce a catalyst electrode layer on the electrolyte membrane to obtain a membrane electrode composite. In addition, the benzenesulfonic acid polymer represented by the general formula (4) was obtained according to the method shown in Example 1 in JP-A-2005-248143.

[Evaluation]
Using the membrane electrode assemblies obtained in the examples and comparative examples, the cell temperature is 80 ° C., the fuel gas is H ₂ gas on the anode side, the air is on the cathode side, and the anode is used in the case of high humidification conditions by the bubbler method. A power generation test was performed under the conditions of a gas humidification dew point of 80 ° C./cathode gas humidification dew point of 80 ° C. and, in the case of low humidification conditions, an anode gas humidification dew point of 45 ° C./cathode gas humidification dew point of 55 ° C., respectively. The back pressure was 0.1 MPa, and the gas flow rate was 0.272 l / min on the anode side and 0.866 l / min on the cathode side. The cell area was 13 cm ² . The obtained current density (A / cm ² ) -voltage curve (V) is shown in FIG. 2 (Example, high humidification condition), FIG. 3 (Example, low humidification condition), and FIG. 4 (Comparative example, high humidification condition). FIG. 5 (Comparative example, low humidification conditions). In the graphs of FIGS. 2 to 5, the curves indicated by thin lines indicate the IV characteristics when benzenesulfonic acid or benzenesulfonic acid polymer is not added, and the curves indicated by bold lines are these. Shows the IV characteristics when is added. As is apparent from FIGS. 2 to 5, the membrane electrode composite obtained in the example to which benzenesulfonic acid was added improved in performance under low humidification conditions, and no significant performance degradation was observed under high humidification conditions. . On the other hand, in the comparative example to which the benzenesulfonic acid polymer was added, performance degradation was observed under low and high humidification conditions. In particular, under high humidification conditions, the amount of performance degradation was large compared to the examples. This is presumably because the drainage and gas diffusibility decreased due to the large molecular size.

  From the above results, the membrane electrode assembly obtained in the example improves the water retention of the catalyst electrode layer by adding benzenesulfonic acid to the catalyst electrode layer. Therefore, when used as a fuel cell, drying of the electrolyte membrane and the catalyst electrode layer can be suppressed, and a decrease in power generation performance under a high-temperature / low-humidity operating environment can be suppressed. Furthermore, since the proton conductivity between the electrolyte membrane and the catalyst electrode layer is improved by improving the affinity and adhesion between the electrolyte membrane and the catalyst electrode layer, a membrane electrode composite with improved output can be obtained. I was able to get it. In addition, since the benzenesulfonic acid is a low molecular compound having a small size of one benzene ring, excess water can be discharged, flooding can be prevented, and reaction gas diffusibility can be improved. For this reason, in particular, the power generation performance does not deteriorate even in a highly humid operating environment with a large amount of generated water. Therefore, it was possible to obtain a membrane electrode assembly exhibiting high power generation characteristics in a wide range of operation from low humidification to high humidification.

It is a schematic sectional drawing which shows an example of a structure of the membrane electrode assembly of this invention. It is a graph which shows the electric current-voltage curve in the electric power generation test (high humidification condition) of the membrane electrode assembly obtained in the Example. It is a graph which shows the electric current-voltage curve in the electric power generation test (low humidification condition) of the membrane electrode assembly obtained in the Example. It is a graph which shows the current-voltage curve in the electric power generation test (high humidification condition) of the membrane electrode assembly obtained by the comparative example. It is a graph which shows the electric current-voltage curve in the electric power generation test (low humidification condition) of the membrane electrode assembly obtained by the comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Membrane electrode complex 2 ... Solid electrolyte membrane 3 ... Anode side catalyst electrode layer 4 ... Cathode side catalyst electrode layer

Claims (3)

A membrane electrode assembly comprising an electrolyte membrane comprising a hydrocarbon-based polymer represented by the following general formula (1) and a catalyst electrode layer disposed on both surfaces of the electrolyte membrane, wherein at least one of the catalyst electrode layers is A membrane electrode composite comprising a benzenesulfonic acid represented by the following general formula (2):

(In the formula, b represents a block copolymer, m and n represent the number of repeating units, and m ≧ 5 and n ≧ 5.)

(In the formula, X is H or a halogen element.)   2. The membrane electrode composite according to claim 1, wherein the catalyst electrode layer containing at least the benzenesulfonic acid represented by the general formula (2) in the catalyst electrode layer contains a fluorocarbon electrolyte polymer. body.   A fuel cell comprising the membrane electrode assembly according to claim 1.

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