JP4921136B2 - Electrolyte membrane for polymer electrolyte fuel cell, electrolyte membrane-electrode assembly, and polymer electrolyte fuel cell - Google Patents

Description

The present invention relates to an electrolyte membrane for a polymer electrolyte fuel cell , an electrolyte membrane-electrode assembly, and a polymer electrolyte fuel cell. In particular, the present invention relates to an electrolyte membrane for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell using the same, and uses a polymer such as hydrogen, reformed hydrogen, methanol, dimethyl ether, etc. as a fuel and air or oxygen as an oxidizing agent The present invention relates to a fuel cell.

  Conventionally, solid polymer electrolyte membranes used in fuel cells and the like include perfluoro proton conductive polymers known under the trade name of Nafion (registered trademark, manufactured by DuPont), and non-perfluoro polymers that do not use fluorine. Examples include proton conductive polymers.

Nafion is a copolymer of perfluorovinyl ether having a sulfonic acid group and tetrafluoroethylene, and is an electrolyte membrane having high conductivity.
On the other hand, a copolymer of an acrylic acid monomer having an ion exchange group and a monomer having high mechanical strength has been proposed as a solid polymer electrolyte membrane made of a non-perfluoro proton conductive polymer that does not use fluorine. (See Non-Patent Document 1)
Proceedings of the Society of Polymer Science, Vol. 48, No. 10, 2393 pages (1999)

  However, Nafion has high proton conductivity, but when using a direct fuel cell that uses liquid fuel such as methanol, the fuel permeability (crossover) is very large and the energy efficiency is not sufficient. There is a point.

  In addition, in a copolymer of an acrylic acid monomer having an ion exchange group and a monomer that is said to have high mechanical strength, increasing the acrylic acid monomer content decreases the mechanical strength, and conversely increases the mechanical strength. When the monomer content is increased, proton conductivity is lowered. Therefore, there is a problem that it is difficult to achieve both good proton conductivity and excellent mechanical strength.

The present invention solves the above-described problems, and provides an electrolyte membrane for a polymer electrolyte fuel cell that has a high performance for preventing crossover of fuel and has both excellent mechanical strength and good proton conductivity. With the goal.

Another object of the present invention is to provide an electrolyte membrane-electrode assembly and a polymer electrolyte fuel cell using the electrolyte membrane for a polymer electrolyte fuel cell.

The present invention relates to an electrolyte membrane for a polymer electrolyte fuel cell comprising a porous polymer membrane and a proton conductive polymer compound filled in pores of the porous polymer membrane, wherein the proton conductive polymer membrane has a high proton conductivity. The electrolyte membrane for a polymer electrolyte fuel cell, wherein the molecular compound has at least a structure represented by the following general formula 1.

(In the formula, R ₁ is a methyl group or a hydrogen atom. R ₂ is a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms containing an ester bond in the main chain. R ₃ is substituted or unsubstituted. An alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted phenylene alkylene group having 7 to 13 carbon atoms, X is a proton conductive group And —SO ₃ H or —R ₄ —SO ₃ H. R ₄ is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and n is an integer of 1 or more.)
Here, the proton conductive group preferably has a structure added to an aromatic ring.

Further, the present invention, the solid and polymer electrolyte fuel cell electrolyte membrane, electrodes and, an electrolyte membrane - an electrode assembly.
Furthermore, the present invention is a polymer electrolyte fuel cell having the electrolyte membrane for a polymer electrolyte fuel cell.

The present invention can provide an excellent mechanical strength and good proton conductivity and formed by both solid polymer electrolyte fuel cell electrolyte membrane.
Furthermore, the present invention provides a polymer electrolyte fuel cell having high output characteristics and excellent durability by using the electrolyte membrane for a polymer electrolyte fuel cell in a polymer electrolyte fuel cell. it can.

Hereinafter, the best mode for carrying out the present invention will be described in detail.
The present invention relates to an electrolyte membrane for a polymer electrolyte fuel cell (hereinafter referred to as “solid polymer electrolyte membrane”) that achieves both excellent mechanical strength and good proton conductivity by using a novel proton conductive polymer compound. Abbreviated as ").) . The present invention also provides an electrolyte membrane-electrode assembly and a solid polymer fuel cell using the solid polymer electrolyte membrane .

  In the present invention, the compound represented by the following general formula 1 (hereinafter sometimes referred to as compound (1)) has a urea bond and a proton conductive group in the same side chain, and is a proton conductive polymer compound It is.

(In the formula, R ₁ is a methyl group or a hydrogen atom. R ₂ is a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms containing an ester bond in the main chain. R ₃ is substituted or unsubstituted. An alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted phenylene alkylene group having 7 to 13 carbon atoms, X is a proton conductive group And —SO ₃ H or —R ₄ —SO ₃ H. R ₄ is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and n is an integer of 1 or more.)

  Urea bonds have strong bond strength and have the property of attracting water by having hydrogen atoms. By having this urea bond, it is possible to produce a film that is strong against compression / swelling and has a flexible mechanical strength. In addition, since the urea bond is present in the same side chain as the proton conductive group, it is easy to attract water to the vicinity of the proton conductive group, and an effect of improving the freedom of movement is obtained.

The proton conductive group in the present invention refers to a functional group having proton conductivity, and examples thereof include a sulfonic acid group, a sulfinic acid group, a carboxylic acid group , and a boronic acid group. Of these, a sulfonic acid group is particularly preferable. This is because the sulfonic acid group has a high degree of acid dissociation and thus has a high effect of improving proton transport efficiency.

  The compound (1) in the present invention is not particularly limited, but is characterized by a structure in which a proton conductive group is added to an aromatic ring as a more preferable basic structure. This is because the proton conductive group is relatively easy to add to the aromatic ring. In addition, by having a proton conductive group in the side chain, it can move relatively freely as compared with the case of having a proton conductive group in the main chain, and thus exhibits good proton conductivity.

  Here, the compound (1) in the present invention is a compound obtained by reacting, for example, an acrylate compound having isocyanate or a methacrylate compound having isocyanate and an amino compound having a proton conductive group (hereinafter referred to as compound (2). May be obtained by polymerization. In compound (2), an isocyanate and an amine react to form a urea bond.

  Here, examples of the acrylate compound having an isocyanate include 2-acryloyloxyethyl isocyanate, methacryloyloxyethyl isocyanate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, and the like.

Examples of the amino compound having a proton conductive group include 3-aminobenzenesulfonic acid and 4-aminobenzenesulfonic acid.
Next, the second solid polymer electrolyte membrane of the present invention will be described.

  The solid polymer electrolyte membrane according to the second aspect of the present invention is obtained by adhering a solution in which a monomer comprising the compound (2) is dissolved or dispersed in a solvent (hereinafter sometimes referred to as a monomer solution) to a support. Created by polymerizing.

  Here, the monomer solution includes at least a monomer composed of the compound (2) and a solvent. Examples of such solvents include amides (N-methylformamide, N-ethylformamide, N, N-dimethylamide, N-methylacetamide, N-ethylacetamide, N-methylpyrrolidinone, N-methyl-2 -Pyrrolidone, etc.), alcohol (ethylene glycol, propylene glycol, glycerin, methyl cellosolve, 1,2 butanediol, 1,3 butanediol, 1,4 butanediol, diglycerin, polyoxyalkylene glycol cyclohexanediol, xylene glycol, etc.) These can be used alone as a solvent, or two or more of them can be used as a solvent. In the present invention, the term “solvent” includes a dispersion medium.

As a method for adhering the solution to the support, methods such as a casting method, a bar coater method, a dip coating method, and a doctor blade method can be used.
In addition, as the support to which the solution is attached, for example, a film, plastic, metal, metal oxide, glass, or the like can be used.

Examples of the method for polymerizing the monomer solution to form a polymer electrolyte membrane include thermal polymerization, photopolymerization, and electron beam polymerization. The method by electron beam polymerization is particularly preferable.
The monomer for obtaining the solid polymer electrolyte membrane according to the second aspect of the present invention may be any monomer as long as it is a monomer of the compound (2), but preferably has a structure represented by the general formula 1.

Further, a monomer other than the monomer of the compound (2) may be added to the monomer of the compound (2) for copolymerization. The monomer can be added, for example, acrylonitrile, methacrylonitrile, vinyl sulfonic acid, allyl sulfonic acid, and styrenesulfonic acid. In this case, it is preferable that monomers other than the monomer of a compound (2) are 5 mol% or more and 50 mol% or less with respect to the monomer of a compound (2).

In addition to the above solvents and monomers, surfactants, filler particles and the like may be added as necessary.
Further, the compound (2) may be used as an electrolyte component by being filled in a porous polymer film. By filling the porous polymer membrane, the strength as the solid polymer electrolyte membrane can be enhanced. In this case, the monomer solution comprising the compound (2) is filled in the porous polymer membrane and then polymerized to be used as a solid polymer electrolyte membrane.

  In the present invention, the porous polymer film is a polymer film having a large number of fine pores. These holes are preferably in the form of a flow path by appropriately connecting the holes. By appropriately connecting the holes, gas and liquid can permeate from one side of the membrane to the opposite side. Here, it is preferable that these holes are connected non-linearly and have a substantial transmission distance. Increasing the substantial permeation distance has the effect of reducing fuel crossover. The degree of permeation can be controlled by the thickness of the porous polymer film and the size of the pores.

  The film thickness and pore size of the porous polymer membrane are selected from the material, the strength of the target electrolyte membrane, the characteristics of the target polymer electrolyte fuel cell, etc., and are not particularly limited. However, when used as a general polymer electrolyte fuel cell, the film thickness is preferably 15 μm or more and 150 μm or less. If the thickness of the porous polymer membrane is less than 15 μm, the effect of strengthening the strength of the membrane is reduced, and if it is greater than 150 μm, the proton moving distance becomes too long, so that the power generation efficiency decreases.

  The porous polymer membrane is made of a polymer material that does not substantially dissolve or swell in methanol and water. Specific examples include resin materials such as polyimide, polytetrafluoroethylene, polyamide, polyimide-amide, polyolefin, and derivatives thereof. Among these, it is particularly preferable to be made of polyimide or a derivative thereof that is most excellent in terms of insolubility in methanol and water, physical strength, heat resistance, shape stability, and chemical stability.

  The method for filling the monomer solution in the porous polymer membrane is not particularly limited. For example, a method of applying the prepared monomer solution to the porous polymer film, a method of filling the pores in the film by dipping, or the like can be used. At this time, the holes can be filled easily by a method such as applying ultrasonic vibration or reducing the pressure. Thereafter, the monomer can be polymerized and cured by performing a conventionally known appropriate method such as thermal polymerization, photopolymerization, or electron beam polymerization. The method by electron beam polymerization is particularly preferable.

In addition, an electrolyte membrane-electrode assembly can be produced using the solid polymer electrolyte membrane thus produced.
FIG. 1 is a schematic view showing an example of the electrolyte membrane-electrode assembly of the present invention. The electrolyte membrane-electrode assembly 11 of this example has electrode catalyst layers 2a and 2b on both surfaces of the solid polymer electrolyte membrane 1, and diffusion layers 3a and 3b on the outside of the electrode catalyst layer.

The electrode catalyst layers 2a and 2b are made of an electrode catalyst in which a catalyst is supported on at least conductive carbon.
Examples of the catalyst include platinum group metals such as platinum, rhodium, ruthenium, iridium, palladium, and osmium, and alloys of platinum and platinum group metals other than platinum. In particular, when methanol is used as the fuel, it is preferable to use an alloy of platinum and ruthenium. The average particle size of the catalyst is preferably small. Specifically, the average particle diameter is preferably 0.5 nm or more and 20 nm or less, and more preferably 1 nm or more and 10 nm or less. If it is less than 0.5 nm, the activity of the catalyst particles alone is too high, and handling becomes difficult. On the other hand, if the thickness exceeds 20 nm, the surface area of the catalyst decreases and the number of reaction sites decreases, which may reduce the activity.

As the conductive carbon, for example, carbon black, carbon fiber, graphite, carbon nanotube, or the like can be used. The average primary particle diameter of the conductive carbon is preferably in the range of 5 nm to 1000 nm, more preferably in the range of 10 nm to 100 nm. However, since the particles are aggregated to some extent during actual use, the preferred range for the average secondary particle size is larger than this range. Further in order to carry the above-mentioned catalyst, the specific surface area ratio of the conductive carbon may large to some degree, preferably less 50 m ² / g or more 3000 m ² / g, more preferably, 100 m ² / g or more 2000 m ² / g or less.

  As a method for supporting the catalyst on the surface of the conductive carbon, for example, the methods described in JP-A-2-111440 and JP-A-2000-003712 can be used. That is, it is a method in which conductive carbon is immersed in a solution of platinum and other noble metals and these noble metal ions are reduced to be supported on the surface of the conductive carbon. Alternatively, a noble metal to be supported may be used as a target and supported on conductive carbon by a vacuum film forming method such as sputtering.

  The electrode catalyst produced in this manner is brought into close contact with the polymer electrolyte membrane and the diffusion layer described later alone or in a state of being mixed with a binder, polymer electrolyte, water repellent, conductive carbon, solvent, and the like.

  The diffusion layers 3a and 3b introduce hydrogen, reformed hydrogen, methanol, dimethyl ether, which is a fuel, and air and oxygen, which are oxidants, into the electrode catalyst layer, and transfer electrons in contact with the electrodes. As such a diffusion layer, a conductive porous film is preferable, and carbon paper, carbon cloth, a composite sheet of carbon and polytetrafluoroethylene, or the like is preferably used. Alternatively, the surface and the inside of the diffusion layer may be coated with a fluorine-based paint and subjected to a water repellent treatment.

In addition, a polymer electrolyte fuel cell can be produced using the electrolyte membrane-electrode assembly produced in this manner.
FIG. 2 is a schematic view showing an example of the polymer electrolyte fuel cell of the present invention. The polymer electrolyte fuel cell of this example has electrodes 4 a and 4 b on both surfaces of the electrolyte membrane-electrode assembly 11. In FIG. 2, a joined body composed of the electrode catalyst layer 2a, the diffusion layer 3a, and the electrode 4a is a fuel electrode (anode) 11a, and a joined body composed of the electrode catalyst layer 2b, the diffusion layer 3b, and the electrode 4b is an air electrode (cathode). ) 11b.

  The electrodes 4a and 4b may be any electrode that can efficiently supply fuel and oxidant to each diffusion layer and can exchange electrons with the diffusion layer. As the electrode material, metals such as nickel, chromium, copper, platinum, palladium, alloys thereof, carbon, carbon dispersed with platinum, iron, or the like can be used. Each of the electrodes 4a and 4b may also serve as a flow path plate for supplying fuel or oxidant gas to the diffusion layers 3a and 3b. That is, the electrodes 4a and 4b do not need to be flat plates, and may have a shape patterned in the current extraction portion and the flow channel.

  The polymer electrolyte fuel cell in the present invention can be obtained by using the electrolyte membrane-electrode assembly of the present invention. FIG. 2 shows an example of the minimum configuration of the polymer electrolyte fuel cell of the present invention, but the actual shape is arbitrary, and a plurality of electrolyte membrane-electrode assemblies are combined in series or in parallel. The shape and manufacturing method are not limited to these.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example. Of the following examples, Examples 5 and 10 are reference examples.
Example 1
THF was placed in the flask and bubbled with Ar for about 30 minutes. Next, 2.4 g of 3-aminobenzenesulfonic acid was added to the flask. When the reaction system was stabilized at 52 ° C., 2.0 g of 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko KK, trade name Karenz AOI) was further dropped into the flask over about 30 minutes. Thereafter, the reaction was allowed to proceed for 12 hours, and then the solvent was removed by a rotary evaporator to obtain 4.1 g of Compound (3). The structure of the compound (3) was confirmed to be a structure represented by the following structural formula 1 by IR analysis.

Example 2
In the synthesis of compound (3), instead of using 2-acryloyloxyethyl isocyanate, methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK, trade name Karenz MOI) was used except that 2.0 g was used. Compound (4) was obtained in the same manner. The compound (4) was similarly confirmed by IR analysis to have the structure represented by the following structural formula 2.

Example 3
In the synthesis of compound (3), compound (5) was synthesized in the same manner as in the synthesis of compound (3) except that 1.8 g of 6-amino-1-naphthalenesulfonic acid was used instead of using 3-aminobenzenesulfonic acid. ) The compound (5) was also confirmed to have the structure represented by the following structural formula 3 by IR analysis.

Example 4
In the synthesis of compound (3), compound (6) was obtained in the same manner as the synthesis of compound (3) except that 3.2 g of 2-aminoethanesulfonic acid was used instead of using 3-aminobenzenesulfonic acid. It was. The compound (6) was also confirmed to have the structure represented by the following structural formula 4 by IR analysis.

Example 5
In the synthesis of compound (3), compound (7) was obtained in the same manner as the synthesis of compound (3) except that 1.5 g of 1-aminoethylphosphonic acid was used instead of using 3-aminobenzenesulfonic acid. It was. The compound (7) was similarly confirmed by IR analysis to have the structure represented by the following structural formula 5.

Example 6
2.0 g of the obtained compound (3) was mixed with 20 g of DMF to obtain a monomer solution. This solution was applied to the surface of a pet film to obtain a coating film having a thickness of 50 μm. Furthermore, after polymerizing by irradiating with an electron beam under the conditions of an acceleration voltage of 200 kV and a dose of 50 kGy using an electron beam irradiation apparatus (CB250 / 15 / 180L manufactured by Iwasaki Electric Co., Ltd.), it is peeled off from the pet film and solidified. A polymer electrolyte membrane 1 was obtained.

Example 7
In the production of the solid polymer electrolyte membrane 1, 2.0 g of the compound (4) is used instead of the compound (3), and the solid polymer electrolyte membrane 2 is formed by the same method as the production method of the solid polymer electrolyte membrane 1. Obtained.

Example 8
In the production of the solid polymer electrolyte membrane 1, 2.0 g of the compound (5) is used instead of the compound (3), and the solid polymer electrolyte membrane 3 is formed by the same method as the production method of the solid polymer electrolyte membrane 1. Obtained.

Example 9
In the production of the solid polymer electrolyte membrane 1, 2.0 g of the compound (6) is used instead of the compound (3), and the solid polymer electrolyte membrane 4 is formed by the same method as the production method of the solid polymer electrolyte membrane 1. Obtained.

Example 10
In the production of the solid polymer electrolyte membrane 1, 2.0 g of the compound (7) is used instead of the compound (3), and the solid polymer electrolyte membrane 5 is formed by the same method as the production method of the solid polymer electrolyte membrane 1. Obtained.

Example 11
2.0 g of the obtained compound (3) was mixed with 20 g of DMF to prepare a monomer solution. A polyimide film having a thickness of 15 μm and an average pore diameter of 0.1 μm was immersed in this solution as a porous polymer film, and the whole container was subjected to ultrasonic treatment for 5 minutes. The polyimide film taken out from the container was transferred onto a smooth SUS plate, and an electron beam with an acceleration voltage of 220 kV and a dose of 50 kGy was applied to the film using an electron beam irradiation device (CB250 / 15 / 180L, manufactured by Iwasaki Electric Co., Ltd.). The front and back surfaces were respectively irradiated and polymerized to obtain a solid polymer electrolyte membrane 6.

Comparative Example 1
THF was placed in the flask and bubbled with Ar for 30 minutes. Next, 1.5 g of p-toluidine was added to the flask. When the reaction system was stabilized at 52 ° C., 2.0 g of 2-acryloyloxyethyl isocyanate (manufactured by Showa Denko KK, trade name Karenz AOI) was further dropped into the flask over about 30 minutes. Thereafter, the reaction was allowed to proceed for 12 hours, and then the solvent was removed by a rotary evaporator to obtain 2.5 g of Compound (8). The structure of the compound (8) was confirmed by IR analysis to be a structure represented by the following structural formula 6.

  Next, 2.0 g of compound (8) was mixed with 10 g of sodium acrylamide-2-methylpropanesulfonate, and then 20 g of DMF was added and stirred to obtain a monomer solution. This solution was applied to the surface of a pet film to obtain a coating film having a thickness of 50 μm. Furthermore, after polymerizing by irradiating with an electron beam under the conditions of an acceleration voltage of 200 kV and a dose of 50 kGy using an electron beam irradiation apparatus (CB250 / 15 / 180L manufactured by Iwasaki Electric Co., Ltd.), it is peeled off from the pet film and solid A polymer electrolyte membrane 7 was obtained.

Comparative Example 2
Synthesis of Compound (9) EO Adduct Diacrylate of Bisphenol A shown in Structural Formula 7 (Kyoeisha Chemical Co., Ltd. Light Acrylate BP-10EA Average Molecular Weight 936) 86.85 g into Dichloroethane (Kishida Chemical Co., Ltd.) 450 ml Dissolved. To this solution, 33.09 g (0.284 mol) of chlorosulfonic acid was added dropwise at 10 ° C. or lower, and then reacted at room temperature for 72 hours. After completion of the reaction, the supernatant solvent of the solution was removed by decantation, 450 ml of dichloroethane was added, and the mixture was allowed to stand with stirring. Thereafter, the supernatant of the solution which was similarly allowed to stand with stirring was removed by decantation. The remaining candy-like product was dissolved in 200 ml of water, taken out, and dried to obtain 83.04 g of the compound (9) represented by the following structural formula 8. In addition, it was confirmed that the structure of the compound (9) was a structure represented by the general formula 3 by NMR analysis.

(However, it is assumed that a + b≈10 in the formula.)

(However, it is assumed that a + b≈10 in the formula.)
Furthermore, 9 g of the obtained compound (9) was mixed with 20 g of vinyl sulfonic acid (manufactured by Asahi Kasei Finechem Co., Ltd.) to obtain a monomer solution. This solution was applied to the surface of a pet film to obtain a coating film having a thickness of 50 μm. Furthermore, after polymerizing by irradiating with an electron beam under the conditions of an acceleration voltage of 180 kV and a dose of 50 kGy using an electron beam irradiation apparatus (CB250 / 15 / 180L manufactured by Iwasaki Electric Co., Ltd.), it is peeled off from the pet film and solidified. A polymer electrolyte membrane 8 was obtained.

Comparative Example 3
The solid polymer electrolyte membrane Nafion 112 (50 μm) commercially available from DuPont was used as it was.

Evaluation (bending test)
Each of the polymer electrolyte membranes of Examples 6 to 11 and Comparative Examples 1 to 3 was cut out to 3 cm × 3 cm, bent at 180 ° with one side end and the center as a crease, and returned to its original state. This process was repeated 100 times, and the surface state of the film was observed. The results are shown in Table 1.

  In Table 1, each of the polymer electrolyte membranes of Examples 6 to 11 and Comparative Examples 1 and 3 showed mechanical strength that can withstand this bending test, but the polymer electrolyte membrane of Comparative Example 2 has mechanical strength. Was insufficient, resulting in white turbidity at the fold.

(Proton conductivity)
The respective solid polymer electrolyte membranes of Examples 6 to 11 and Comparative Examples 1 to 3 were cut into 3 cm × 2 mm and fixed on platinum electrodes provided with an interval of 1 cm. Further, the proton conductivity of each solid polymer electrolyte membrane was measured with an impedance analyzer SI1260 manufactured by Solartron under an environment of a temperature of 50 ° C. and a relative humidity of 95%. The results are shown in Table 2.

(Discharge characteristics)
A polymer electrolyte fuel cell was produced in the following procedure.
Two carbon pavers (TGP-H-060 manufactured by Toray Industries, Inc.) having a thickness of 0.2 mm and a size of 5 cm × 5 cm were prepared. One of them was loaded with 1.5 mg / cm ² of a platinum catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) as a fuel electrode catalyst. The remaining one sheet was loaded with 1.5 mg / cm ² of a platinum-ruthenium catalyst (TEC61E54 manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) as an oxidant electrode catalyst to form an oxidant electrode (air electrode).

  The polymer solid electrolyte membranes of Examples 6 to 11 and Comparative Examples 1 to 3 were cut into 7.5 cm × 7.5 cm squares. The polymer solid electrolyte membrane cut out between the fuel electrode and the oxidant electrode produced as described above was sandwiched and pressed under the conditions of a temperature of 120 ° C. and a pressure of 10 MPa to produce an electrolyte membrane-electrode assembly.

  The obtained electrolyte membrane-electrode assembly was mounted on a direct methanol fuel cell test cell (EFC25-01DM, manufactured by Electrochem) to produce a solid polymer fuel cell. The cell temperature was maintained at 70 ° C., and an 8% methanol aqueous solution as fuel and oxygen as the oxidant were supplied to obtain a current-voltage curve.

Table 2 shows the terminal voltages when the polymer electrolyte fuel cell produced by the above procedure was discharged at a current density of 0.20 A / cm ² .

  From the results in Table 2, it can be seen that the solid polymer electrolyte membranes of Examples 6 to 11 have lower proton conductivity but higher terminal voltage during power generation than the Nafion membrane of Comparative Example 3. This is probably because the solid polymer electrolyte membranes of Examples 6 to 11 were more effective in reducing methanol crossover than the Nafion membrane of Comparative Example 3, and thus the terminal voltage was increased. When the Nafion membrane of Comparative Example 3 was used, the proton conductivity was good, but the terminal voltage was low due to the remarkable methanol crossover.

  In the film of Comparative Example 2, the voltage decreased to the values shown in Table 2 while power generation was continued. This is considered to be caused by the occurrence of cracks in the membrane due to insufficient mechanical strength of the membrane against the movement of membrane compression and swelling caused by the flow of fuel in the cell. It is presumed that the voltage was lowered due to cracks in the film.

By using the compound of the present invention, it is possible to provide a solid polymer electrolyte membrane that achieves both excellent mechanical strength and good proton conductivity.
In addition, by using the solid polymer electrolyte membrane as an electrolyte membrane of a fuel cell, a solid polymer fuel cell having a high effect of suppressing fuel permeation can be provided.

It is a schematic diagram which shows an example of the electrolyte membrane-electrode assembly of this invention. It is a schematic diagram which shows an example of the polymer electrolyte fuel cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid polymer electrolyte membrane 2a, 2b Electrode catalyst layer 3a, 3b Diffusion layer 4a, 4b Electrode 11 Electrolyte membrane-electrode assembly 11a Fuel electrode (anode)
11b Air electrode (cathode)

Claims (4)

An electrolyte membrane for a polymer electrolyte fuel cell comprising a porous polymer membrane and a proton conductive polymer compound filled in pores of the porous polymer membrane, wherein the proton conductive polymer compound is at least An electrolyte membrane for a polymer electrolyte fuel cell, characterized by having a structure represented by the following general formula 1.

(Wherein R ₁ Is a methyl group or a hydrogen atom. R ₂ Is a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms and containing an ester bond in the main chain. R ₃ Is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, a substituted or unsubstituted phenylene group or a substituted or unsubstituted phenylene alkylene group having 7 to 13 carbon atoms. X is a proton conductive group, -SO ₃ H or -R ₄ -SO ₃ H. R ₄ Is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms. n is an integer of 1 or more. ) The electrolyte membrane for a polymer electrolyte fuel cell according to claim 1, wherein the proton conductive group has a structure added to an aromatic ring. A solid polymer electrolyte membrane according to claim 1 or 2, the electrolyte membrane, wherein the electrode, in that it consists of - electrode assembly. A polymer electrolyte fuel cell comprising the electrolyte membrane for a polymer electrolyte fuel cell according to claim 1 or 2 as an electrolyte membrane .

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