KR20080041844A - Membrane-electrode assembly for fuel cell, method of producing same, and fuel cell system comprising same - Google Patents

Abstract

A membrane-electrode assembly for a fuel cell is provided to realize excellent cost-efficiency by reducing the amount of a catalyst while maintaining a high output, and to avoid a need for an additional activation step. A membrane-electrode assembly(17) for a fuel cell comprises: a polymer electrolyte membrane; and an anode and a cathode comprising a catalyst layer and disposed on both surfaces of the polymer electrolyte membrane, wherein the catalyst layer comprises a catalyst, a binder and an ionic liquid. The ionic liquid comprises an organic cation. The organic cation includes a cation of heterocyclic compound. The heterocyclic compound has a heteroatom selected from the group consisting of N, O, S and a combination thereof.

Description

Membrane-electrode assembly for fuel cell, method for manufacturing same, and system for fuel cell comprising same {MEMBRANE-ELECTRODE ASSEMBLY FOR FUEL CELL, METHOD OF PRODUCING SAME, AND FUEL CELL SYSTEM COMPRISING SAME}

1 is a view schematically showing the structure of a fuel cell system of the present invention.

[Industrial use]

The present invention relates to a fuel cell membrane-electrode assembly, a method for manufacturing the same, and a fuel cell system including the same. More particularly, the fuel cell membrane-electrode can be manufactured economically and simply by reducing the amount of catalyst used. An assembly, a method of manufacturing the same, and a fuel cell system including the same.

[Prior art]

A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in hydrocarbon-based materials such as methanol, ethanol and natural gas into electrical energy.

Representative examples of the fuel cell system include a polymer electrolyte fuel cell (PEMFC) and a direct oxidation fuel cell (Direct Oxidation Fuel Cell). When methanol is used as a fuel in the direct oxidation fuel cell, it is called a direct methanol fuel cell (DMFC).

The polymer electrolyte fuel cell is a clean energy source that can replace fossil energy, and has high power density and energy conversion efficiency, can be operated at room temperature, and can be miniaturized and encapsulated. It can be widely used in fields such as portable power supply and military equipment.

The polymer electrolyte fuel cell has an advantage of having a high energy density, but requires attention to handling hydrogen gas and a unit such as a fuel reformer for reforming methane, methanol, natural gas, etc. to produce hydrogen as fuel gas. There is a problem requiring equipment.

In contrast, the direct oxidation fuel cell has a lower energy density than the polymer electrolyte fuel cell, but is easy to handle in a liquid state and has a low operating temperature, and thus can be operated at room temperature. As a result, it is recognized as a system suitable as a compact and general-purpose mobile power supply. In addition, the stack configuration by stacking unit cells has the advantage that can produce a wide range of output, it is attracting attention as a new portable power source because it shows an energy density of 4-10 times compared to a small lithium battery.

In such fuel cell systems, the stack that substantially generates electricity may comprise several to several unit cells consisting of a membrane-electrode assembly (MEA) and a separator (also known as a bipolar plate). It has a structure stacked in dozens. The membrane-electrode assembly is called an anode electrode (also called "fuel electrode" or "oxide electrode") and a cathode electrode (also called "air electrode" or "reduction electrode") with a polymer electrolyte membrane including a hydrogen ion conductive polymer therebetween. Has a bonded structure.

It is an object of the present invention to provide an economical fuel cell membrane-electrode assembly that can reduce the amount of catalyst used.

Another object of the present invention is to provide a method for manufacturing a membrane-electrode assembly for a fuel cell, which can easily manufacture the membrane-electrode assembly.

It is another object of the present invention to provide a fuel cell system comprising the membrane-electrode assembly.

In order to achieve the above object, the present invention provides a polymer electrolyte membrane and a fuel cell membrane-electrode assembly including an anode electrode and a cathode electrode formed on both surfaces of the polymer electrolyte membrane and including a catalyst layer. The catalyst layer comprises a catalyst, a binder and an ionic liquid.

The present invention also coats a catalyst composition comprising a catalyst, a binder, a thickener, an ionic liquid and a solvent on a porous release film, places a polymer electrolyte membrane on one side of the porous release film coated with the catalyst composition, and then hot rolls the catalyst. And transferring the catalyst layer including the binder and the ionic liquid to the polymer electrolyte membrane and removing the porous release film from the catalyst layer transferred to the polymer electrolyte membrane.

The invention also provides a fuel cell system comprising at least one electricity generator, a fuel supply and an oxidant supply. The electricity generating unit includes at least one membrane-electrode assembly of the present invention, includes a separator, and serves to generate electricity through an oxidation reaction of a fuel and a reduction reaction of an oxidant. The fuel supply unit serves to supply fuel to the electricity generation unit, and the oxidant supply unit serves to supply an oxidant to the electricity generation unit.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a membrane-electrode assembly for a fuel cell which can reduce the amount of catalyst used and can be manufactured economically.

The membrane-electrode assembly for a fuel cell of the present invention is provided on both sides of a polymer electrolyte membrane and the polymer electrolyte membrane, and provides a membrane-electrode assembly for a fuel cell including an anode electrode and a cathode electrode including a catalyst layer. The catalyst layer comprises a catalyst, a binder and an ionic liquid.

Since the ionic liquid is present in a liquid state, it is possible to prevent excessive drying even when the membrane-electrode assembly of the present invention is stored for a long time, and also used when manufacturing a fuel cell system using the membrane-electrode assembly. In order for the high molecular electrolyte membrane to work in the process, it is not necessary to perform an activation process for imparting humidification conditions separately. Therefore, there is a simple advantage in use.

The ionic liquid includes an organic cation and an anion that binds to the organic cation.

As said organic cation, the cation of a heterocyclic compound is preferable. The hetero atom of the heterocyclic compound is selected from N, O, S or a combination thereof, and the number of hetero atoms is preferably 1 to 4, more preferably 1 to 2 atoms. Cations of such heterocyclic compounds include pyrididinium, pyrididazinium, pyrimidinium, pyrazinium, imidazolium, pyrazolium, thiazolium Cations of a compound selected from the group consisting of Thiazolium, Oxazolium, and Triazolium, or substituted compounds thereof.

The ionic liquid may further comprise an anion bound to an organic cation.

The anion is preferably a non-Lewis acid containing a polyvalent anion having a van der Waals volume of 100Å ³ or more. The larger the van der Waals volume of the anion, the lower the lattice energy of the molecule and the better the ion conductivity.

More preferably, the ionic liquid is selected from the group having the structural formulas of the following Chemical Formulas 1-9.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

In Chemical Formulas 1 to 9, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ may be H, a halogen, or an alkyl group having 1 to 4 carbon atoms, or may be bonded to each other to surround N. alkylene, having 2 to 4 carbon atoms to form a is to configure it or remove group constituting a radical, and the alkyl groups, alkylene radicals or phenyl groups is _{^{F -, Cl -, CF 3}} -, SF 5 -, CF ^{_{3 S -, (CF 3)}} 2 CHS - and (CF _{3) 3} CS ^- can be substituted with electron withdrawing (electron-withdrawing) is selected from the group consisting of and and X ^- is a van der Waals volume exceeding 100Å ³ It is a non-Lewis acid containing the polyvalent anion which has.

Wherein X is more preferably ^- is _{^{CF 3 CO 2 -, CF 3}} SO 3 -, BF 4 -, PF 6 -, - O- (SO 2 R), - N- (SOR) 2, - C- ( _{SO 2 R) 3, BR 4} -, PR 6 -, bis (perfluoroethyl sulfonyl) imide _{(N (C 2 F 5 SO} 2) 2 -, Beti), methyl-sulfonyl-bis (trifluoromethyl) Imide) (N (CF ₃ SO ₂ ) ₂ ⁻ , Im), tris (trifluoromethylsulfonylmethide) (C (CF ₃ SO ₂ ) ₂ ⁻ , Me), trifluoromethanesulfonimide, trifluoromethoxy naphthyl sulfonimide, methyl sulfonate, _{^{trifluoromethyl, AsF 6 -, ClO 4 -}} , and is selected from the group consisting of, wherein R is hydrogen, an alkyl group, a hydroxyl group having 1 to 12 carbon atoms, having a carbon number of 1 It is selected from the group consisting of alkoxy groups of 6 to 6 and combinations thereof.

In the present invention, the ionic liquid is preferably included in 20 to 50% by weight, more preferably 30 to 40% by weight in the total weight of the electrode. If the weight of the ionic liquid is less than 20% by weight, the amount is so small that the catalyst layer becomes completely dry, which is undesirable because the catalyst layer may be broken. If the amount of the ionic liquid exceeds 50% by weight, the catalyst layer may be excessively evaporated. It is not desirable to have.

As the catalyst, any one that can be used as a catalyst may participate in the reaction of the fuel cell, and as a representative example, a platinum-based catalyst may be used. The platinum-based catalyst may be platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy or platinum-M alloy (Ga, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Mo, W, Rh, Ru and a transition metal selected from the group consisting of a combination thereof) can be used one or more catalysts selected from. Specific examples include Pt, Pt / Ru, Pt / W, Pt / Ni, Pt / Sn, Pt / Mo, Pt / Pd, Pt / Fe, Pt / Cr, Pt / Co, Pt / Ru / W, Pt / Ru One or more selected from the group consisting of / Mo, Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni, and Pt / Ru / Sn / W can be used.

In addition, such a metal catalyst may be used as the metal catalyst (black) itself, or may be supported on a carrier. As the carrier, carbonaceous materials such as graphite, denka black, ketjen black, acetylene black, carbon nanotubes, carbon nanofibers, carbon nanowires, carbon nanoballs or activated carbon may be used, or alumina, silica, zirconia, Inorganic fine particles such as titania may be used, but carbon-based materials are generally used. In the case of using the noble metal supported on the carrier as a catalyst, a commercially available commercially available product may be used, or the noble metal supported on the carrier may be prepared and used. Since the process of supporting the precious metal on the carrier is well known in the art, detailed descriptions thereof will be readily understood by those skilled in the art even if the detailed description is omitted.

The loading amount of the catalyst in the electrode of the present invention is 2 to 4 mg / cm ² , can be made less than about 6 to 8 mg / cm ² conventionally, without causing a decrease in battery output, it can reduce the amount of expensive catalyst used It is economical.

The binder may be a fluoro-based polymer such as perfluorosulfonate, a polyamide-based polymer, a polyether-based polymer, a benzimidazole-based polymer, a polyimide-based polymer, a polyetherimide-based polymer, or a polyphenylene sulfide-based polymer. At least one hydrogen ion conductive polymer such as a polymer, a polysulfone polymer, a polyether sulfone polymer, a polyether ketone polymer, a polyether ether ketone crab polymer or a polyphenylquinoxaline polymer may be used. The hydrogen ion conductive polymer may replace H with Na, K, Li, Cs or tetrabutylammonium in an ion exchange group at the side chain end. In case of replacing H with Na in the side chain terminal ion exchanger, NaOH is substituted for the preparation of the catalyst composition, and tetrabutylammonium hydroxide is substituted for tetrabutylammonium, and K, Li or Cs may be substituted with appropriate compounds. It can be substituted using. Since this substitution method is well known in the art, detailed description thereof will be omitted.

The binder may be used in the form of a single substance or a mixture, and may also be optionally used with a nonconductive polymer for the purpose of further improving adhesion to the polymer electrolyte membrane. It is preferable to adjust the usage-amount so that it may be suitable for a purpose of use.

The non-conductive polymer may be polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro alkyl vinyl ether copolymer ethylene / tetrafluoroethylene, chloro Copolymers of trifluoroethylene-ethylene copolymer, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene, dodecylbenzenesulfonic acid, sorbitol, and combinations thereof. Can be.

In addition, an electrode substrate generally used in the anode and cathode electrodes of the fuel cell is located on one surface of the catalyst layer.

The electrode substrate plays a role of supporting the electrode and diffuses the fuel and the oxidant to the catalyst layer, thereby serving to easily access the fuel and the oxidant to the catalyst layer. A conductive substrate is used as the electrode substrate, and representative examples thereof include carbon paper, carbon cloth, carbon felt, or metal cloth (porous film or polymer composed of metal cloth in a fibrous state). It means that the metal film is formed on the surface of the cloth formed of fibers) may be used, but is not limited thereto.

In addition, it is preferable to use a water-repellent treatment with a fluorine-based resin as the electrode base material because it can prevent the reactant diffusion efficiency from being lowered by water generated when the fuel cell is driven. Examples of the fluorine-based resin include polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride alkoxy vinyl ether, and fluorinated ethylene propylene ( Fluorinated ethylene propylene), polychlorotrifluoroethylene or copolymers thereof can be used.

In addition, a microporous layer may be further included to enhance the reactant diffusion effect in the electrode substrate. These microporous layers are generally conductive powders having a small particle diameter, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotubes, carbon nanowires, and carbon nanohorns. -horn or carbon nano ring.

In addition, a microporous layer may be further included to enhance the reactant diffusion effect in the electrode substrate. These microporous layers are generally conductive powders having a small particle diameter, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotubes, carbon nanowires, and carbon nanohorns. -horn or carbon nano ring.

The microporous layer is prepared by coating a composition comprising a conductive powder, a binder resin and a solvent on the electrode substrate. The binder resin may be polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxy vinyl ether, polyvinyl alcohol, cellulose acetate Or copolymers thereof and the like can be preferably used. As the solvent, alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, water, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, etc. may be preferably used. The coating process may be screen printing, spray coating, or coating using a doctor blade according to the viscosity of the composition, but is not limited thereto.

In the membrane-electrode assembly of the present invention, a polymer electrolyte membrane is generally used as a polymer electrolyte membrane in a fuel cell, and any one made of a polymer resin having hydrogen ion conductivity may be used. Representative examples thereof include a polymer resin having a cation exchange group selected from the group consisting of sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups and derivatives thereof in the side chain.

Representative examples of the polymer resin include a fluorine polymer, a benzimidazole polymer, a polyimide polymer, a polyetherimide polymer, a polyphenylene sulfide polymer, a polysulfone polymer, a polyether sulfone polymer and a polyether ketone It may include one or more selected from a polymer, a polyether-ether ketone-based polymer or a polyphenylquinoxaline-based polymer, more preferably poly (perfluorosulfonic acid) (generally marketed as Nafion), Poly (perfluorocarboxylic acid), copolymers of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid groups, defluorinated sulfide polyether ketones, aryl ketones, poly (2,2'-m-phenylene) Or at least one selected from -5,5'-bibenzimidazole (poly (2,2 '-(m-phenylene) -5,5'-bibenzimidazole) or poly (2,5-benzimidazole) Can be.

In the hydrogen ion conductive group of the hydrogen ion conductive polymer, H may be substituted with Na, K, Li, Cs or tetrabutylammonium. In case of replacing H with Na in the side chain terminal ion exchanger, NaOH is substituted for the preparation of the catalyst composition, and tetrabutylammonium hydroxide is substituted for tetrabutylammonium, and K, Li or Cs may be substituted with appropriate compounds. It can be substituted using. Since this substitution method is well known in the art, detailed description thereof will be omitted.

The membrane-electrode assembly for a fuel cell of the present invention is manufactured by the following process.

The catalyst composition is coated on the release film to form a catalyst layer. The release film is preferably composed of a polymer that does not react with the catalyst, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyethylene terephthalate terephthalate) or polyesters.

The catalyst composition comprises a catalyst, a binder, an ionic liquid and a thickener. At this time, since the ionic liquid may also serve as a solvent, a solvent may be used separately, and of course, a solvent may be further used. In the catalyst composition, the content of the catalyst, the binder, the ionic liquid and the thickener is preferably 10 to 25 parts by weight of the binder, 75 to 150 parts by weight of the thickener and 20 to 50 parts by weight of the ionic liquid, based on 100 parts by weight of the catalyst, More preferred are 10 to 20 parts by weight of the binder, 30 to 40 parts by weight of the ionic liquid and 70 to 140 parts by weight of the thickener. In this case, when using a solvent, it is appropriate to use the same amount as the catalyst. When the composition of the catalyst composition is in the above range, after the membrane-electrode assembly is manufactured, the catalyst, the binder, the ionic liquid, and the moisture in the catalyst layer may be smoothly formed in the three-phase interface. It is not desirable because one component of the electrical resistance, ionic resistance or mass transfer resistance increases excessively.

The catalyst, binder and ionic liquid are as described above.

When the thickener is formed directly on the polymer electrolyte membrane, the solvent included in the composition for forming the catalyst layer penetrates into the polymer electrolyte membrane and swells the polymer electrolyte membrane to prevent structural stability of the membrane-electrode assembly. However, since the thickener may be decomposed chemically during the redox reaction caused by the fuel cell operation when remaining in the catalyst layer, thereby decreasing the ion conductivity or the electron conductivity of the catalyst layer, the catalyst layer does not remain in the catalyst layer of the finally prepared membrane-electrode assembly. It is preferable to remove by acid treatment after formation.

As the thickener, glycol types such as glycerol, dipropylene glycol, diethylene glycol, ethyl cellulose, hydroxypropyl cellulose, methyl cellulose, castor oil derivatives, or a combination thereof may be used.

The solvent may be water, methanol, ethanol, alcohol such as isopropyl alcohol, N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, acetone or a combination thereof.

The viscosity of the catalyst layer composition of the present invention is preferably 500 to 7000 cps, more preferably 3000 to 5000 cps. If the viscosity of the catalyst composition is less than 500cps, there is a problem that the high-density platinum particles are settled, and if the viscosity of the catalyst composition is higher than 7000cps, the original shape is not maintained, which is not preferable.

Next, the polymer electrolyte membrane is placed on the catalyst layer formed on the release film. At this time, the ionic liquid penetrates into the polymer electrolyte membrane and is then hot rolled to transfer the catalyst layer to the polymer electrolyte membrane.

The polymer electrolyte membrane is as described above.

The hot rolling step is preferably carried out at a temperature of 100 to 150 ℃, preferably at a pressure of 500 to 1000 psi. When the hot rolling process is performed at a temperature below 100 ° C., the hydrogen ion conductive polymers of the catalyst layer and the polymer electrolyte membrane do not bind to each other, and when the temperature is higher than 150 ° C., thermal and physical decomposition (ion / cluster region) It is unfavorable because it may shrink so much that it will not swell again by moisture and the initial resistance may become excessively high.

In addition, in the present invention, thermal stability is improved when a binder of the catalyst layer composition and a hydrogen-conductive polymer of the polymer electrolyte membrane are substituted with H, Na, K, Li, Cs, or tetrabutylammonium in the hydrogen-ion conductive group. Therefore, even if the hot rolling process is performed at 200 ° C. or more, there is no fear that the ionomer binder and the hydrogen ion conductive polymer deteriorate or the life of the fuel cell is reduced accordingly. In addition, when substituted with Na, K, Li, Cs or tetrabutylammonium, the catalyst layer is then subjected to an acid treatment, which results in a proton type (H ⁺ -form) polymer electrolyte membrane.

In addition, in the hot rolling process, the pressure needs to be adjusted to obtain an optimum state of electrical conductivity, ion conductivity, and mass transport. When the pressure is higher than 500 psi, the catalyst layer becomes too compact to react with the reactant. It is not preferable because the resistance is increased and the diffusion resistance (diffusion resistance) in terms of the inflow and removal of the fuel and the oxidant is not preferable, and if the pressure is lower than 1000 psi, the electron and ion conduction resistance may be high.

All of the solvent is volatilized in the hot rolling process, but only a very small amount of the ionic liquid volatilizes to be almost in a liquid state. As a result, when the membrane-electrode assembly is manufactured without using the conventional ionic liquid, the problem of complicated process can be solved.

In the case of manufacturing a membrane-electrode assembly without using a conventional ionic liquid, if the thermal compression process is performed as it is, deterioration occurs and the hydrogen ion conductive polymer (ie, ionomer) is transformed into a thermoplastic form, followed by thermocompression. Since the process was carried out and the process of converting the hydrogen ion conductive polymer changed into the thermoplastic form into H ⁺ form having hydrogen ion conductivity by chemical conversion, the process was complicated.

When the pressing process is completed, the release film is removed from the catalyst layer transferred to the polymer electrolyte membrane. According to this process, a product in which a catalyst layer is bonded to one surface of a polymer electrolyte membrane is obtained. When the same process is performed on the other surface of the polymer electrolyte membrane, a membrane-electrode assembly having catalyst layers formed on both surfaces of the polymer electrolyte membrane is obtained.

Subsequently, in the case of using the ionomer binder and the polymer electrolyte membrane in which H of the hydrogen ion conductive group is substituted with Na, K, Li, Cs or tetrabutylammonium, an acid treatment is performed to perform Na, K, Li, Cs or tetra Butyl ammonium is again replaced with a proton form (H ⁺ -form). The acid treatment may be performed by treating the membrane-electrode assembly with an acid at 80 to 100 ° C. and washing with water. Sulfuric acid is typically used as the acid, but is not limited thereto. Generally, an aqueous sulfuric acid solution having a concentration of about 1 M is used.

The membrane-electrode assembly of the present invention having the above configuration is used in an electricity generating unit, and the fuel cell system of the present invention including the same includes at least one electricity generating unit, a fuel supply unit, and an oxidant supply unit.

The electricity generator includes the membrane-electrode assembly of the present invention and also includes a separator (also called a bipolar plate). The electricity generation unit serves to generate electricity through the oxidation reaction of the fuel and the reduction reaction of the oxidant.

The fuel supply unit serves to supply fuel to the electricity generation unit, and the oxidant supply unit serves to supply an oxidant such as oxygen or air to the electricity generation unit. In the present invention, the fuel refers to a hydrocarbon fuel such as methanol, ethanol, propanol, butanol, and natural gas in a gas or liquid state. Of course, hydrogen can also be used.

A schematic structure of the fuel cell system of the present invention is shown in FIG. 1, which will be described in more detail with reference to the following. Although the structure shown in FIG. 1 shows a system for supplying fuel and oxidant to an electric generator using a pump, the fuel cell system of the present invention is not limited to such a structure, and a fuel cell using a diffusion method without using a pump is shown. Of course, it can also be used for system architecture.

The fuel cell system 1 of the present invention includes at least one electricity generation unit 3 for generating electrical energy through an oxidation reaction of a fuel and a reduction reaction of an oxidant, a fuel supply unit 5 for supplying the fuel, And an oxidant supply unit 7 for supplying an oxidant to the electricity generation unit 3.

In addition, the fuel supply unit 5 for supplying the fuel may include a fuel tank 9 storing fuel and a fuel pump 11 connected to the fuel tank 9. The fuel pump 11 serves to discharge the fuel stored in the fuel tank 9 by a predetermined pumping force.

The oxidant supply unit 7 for supplying the oxidant to the electricity generating unit 3 includes at least one oxidant pump 13 for sucking the oxidant with a predetermined pumping force.

The electricity generator 3 is composed of a membrane-electrode assembly 17 for oxidizing and reducing a fuel and an oxidant, and a separator 19 and 19 'for supplying fuel and an oxidant to both sides of the membrane-electrode assembly. At least one of these electricity generating units 3 constitutes a stack 15.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

(Example 1)

5.0 g Pt-Ru black (Johnson Matthey, HiSpec 6000) anode catalyst and Pt black (Johnson Matthey, HiSpec 100) cathode catalyst, respectively, were wetted with 5.0 g of deionized water, respectively, and then 10.0 g of 5% Nafion. / H ₂ O / 2-propanol (Solution Technology Inc.), 0.5 g of 1M tetrabutylammonium hydroxide / methanol (Aldrich) and an ionic liquid with cation imidazolium and anion AsF ₆ ⁻ Mechanical stirring at room temperature for 6 hours, and mechanically stirred at room temperature for 6 hours by adding 10 g of dipropylene glycol to prepare an anode catalyst slurry and a cathode catalyst slurry, respectively. In this process, H of the Nafion is present as tetrabutylammonium type Nafion substituted with tetrabutylammonium.

The anode catalyst slurry and the cathode catalyst slurry were screen printed on a polytetrafluoroethylene release film having a thickness of 75 μm at 5 × 5 cm ² , respectively, and then dried in a nitrogen atmosphere at 50 ° C. for 12 hours. In this process, an anode catalyst layer and a cathode catalyst layer were formed on the surface of the polytetrafluoroethylene film, respectively. At this time, the final catalyst loading was adjusted to 3mg / cm ² respectively.

Subsequently, a sodium foam perfluorosulfonate polymer electrolyte membrane (Na + -form Nafion 115) was placed between the catalyst layers of the polytetrafluoroethylene film having the anode catalyst layer and the cathode catalyst layer formed thereon, and then the temperature of 130 ° C. and 750 psi. The film was hot rolled at a pressure of 3 minutes to bond the polymer electrolyte membrane and the catalyst layer. Subsequently, after removing the porous polytetrafluoroethylene release film, the catalyst-coated polymer electrolyte membrane was treated in a 1M sulfuric acid solution at 100 ° C. for 1 hour to replace the perfluorosulfonate with proton-form (H ⁺ -form). After treatment for 1 hour in deionized water at 100 ℃, and dried at room temperature.

Finally, the gas diffusion layer (SGL Carbon, 31BC) on which the microporous layer is formed is bound to both the catalyst layer at a temperature of 130 ° C. and a pressure of 500 psi to form anode and cathode electrodes on both sides of the polymer electrolyte membrane. A membrane-electrode assembly for a battery was prepared.

The fuel cell membrane-electrode assembly is inserted between two gaskets, and then inserted into two separators having a predetermined gas flow channel and a cooling channel and pressed between copper end plates to manufacture a unit cell. It was.

While maintaining the unit cell at 70 ° C., 1M methanol and ambient air were stoichiometry (the amount of methanol supplied to the anode / the amount of air supplied to the cathode, and the theoretical value for the electrochemical reaction) = 0.4 / 3.0, and the flow was 0.4 V. The current density and power density were investigated at the operating voltage of.

(Comparative Example 1)

A unit cell was prepared in the same manner as in Example 1 except that no ionic liquid was added.

(Comparative Example 2)

A unit cell was prepared except that the hot rolling process was conducted at 130 ° C. under 1500 psi pressure.

The power densities of the fuel cells prepared in Example 1 and Comparative Examples 1 and 2 were measured at 70 ° C. As a result, a very high output density was obtained in Example 1 compared to Comparative Examples 1 and 2. This is because, in the case of Comparative Example 1, the polymer electrolyte membrane was deteriorated in the hot rolling process, and the output density was very low.In the case of Comparative Example 2, as the hot rolling process was performed at too high pressure, the diffusion resistance was increased and the output density was deteriorated. do. On the contrary, in Example 1, the deterioration of the polymer electrolyte membrane did not occur in the hot rolling process due to the use of the ionic liquid.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

As described above, the membrane-electrode assembly for a fuel cell of the present invention can be manufactured economically because high output can be obtained even if the catalyst loading amount is reduced, and an activation process for imparting additional humidification conditions is not required.

Claims (28)

Polymer electrolyte membranes; And Located on both sides of the polymer electrolyte membrane, including an anode electrode and a cathode electrode including a catalyst layer, The catalyst layer is catalyst; bookbinder; And Ionic liquid To include Membrane-electrode assembly for fuel cell. The method of claim 1, Wherein the ionic liquid comprises an organic cation. The method of claim 2, The organic cation is a cation of a heterocyclic compound, the fuel cell membrane electrode assembly. The method of claim 3, The heterocyclic compound is a fuel cell membrane-electrode assembly comprising a hetero atom selected from the group consisting of N, O, S and combinations thereof. The method of claim 3, The heterocyclic compound is a fuel cell membrane electrode assembly comprising 1 to 4 hetero atoms. The method of claim 3, The cation of the heterocyclic compound is imidazolium (Imidazolium), pyrazolium, Tiazolium (Triazolium), Thiazolium (Thiazolium), Oxazolium, Pyridinium, Pyridazinium, Pyridazinium Membrane (Pyrimidinium), pyrazinium (Pyrazinium) is a compound selected from the group consisting of or a cation of a substituted compound thereof. The method of claim 1, The ionic liquid includes an anion bonded to an organic cation, wherein the anion is a non-Lewis acid containing a polyvalent anion having a van der Waals volume of 100 이상의 ³ or more. The method of claim 3, Wherein the ionic liquid is selected from the group consisting of the structural formula of Formula 1 to 9 fuel cell membrane electrode assembly. [Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

(In Formulas 1 to 9, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are H, a halogen, or an alkyl group having 1 to 4 carbon atoms, or are bonded to each other to surround N. is to configure it or separate phenyl groups constituting the alkylene group, having 2 to 4 radicals to form the structure, and the alkyl, alkylene radicals or phenyl groups is _{^{F -, Cl -, CF 3}} -, SF 5 -, ^{_{CF 3 S -, (CF 3}} ) 2 CHS - and (CF _{3) 3} CS ^- as can be substituted with electron withdrawing selected from the group consisting of, and X ^- is an anion polyhydric having a van der Waals volume exceeding 100Å ³ It is a non-Lewis acid containing The method of claim 8, Wherein X ^- is ^{_{CF 3 CO 2 -, CF 3}} SO 3 -, BF 4 -, PF 6 -, - O- (SO 2 R), - N- (SOR) 2, - C- (SO 2 R) 3 ^{_{, BR 4 -, PR 6 -}} , bis (perfluoroethyl sulfonyl) imide _{(N (C 2 F 5 SO} 2) 2 -, Beti), ( methylsulfonyl-trifluoromethyl) bis imide) (N ^{_{(CF 3 SO 2) 2 -}} , Im), tris (trifluoromethyl sulfonyl _{methide) (C (CF 3 SO 2} ) 2 -, Me), trifluoromethane sulfonimide, trifluoromethyl sulfonic Nate already-methyl-de, trifluoromethyl sulfonate, AsF ₆ ^-, ClO ₄ ^-, and will be selected from the group consisting of a combination thereof, wherein R is an alkyl group of a hydrogen, 1 to 12 carbon atoms, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms Membrane-electrode assembly for a fuel cell. The method of claim 1, The ionic liquid is 20 to 50% by weight based on the total weight of the electrode membrane-electrode assembly for a fuel cell. The method of claim 10, Wherein the ionic liquid is 30 to 40% by weight of the total weight of the electrode membrane-electrode assembly for a fuel cell. Coating the release film with a catalyst composition comprising a catalyst, a binder, a thickener, an ionic liquid and a solvent; Placing the polymer electrolyte membrane on the release film coated with the catalyst composition, and then hot rolling to transfer the catalyst layer including the catalyst, the binder and the ionic liquid to the polymer electrolyte membrane; Removing the release film from the catalyst layer transferred to the polymer electrolyte membrane A method of manufacturing a membrane-electrode assembly for a fuel cell comprising a step. The method of claim 12, The hot rolling process is a method for producing a membrane-electrode assembly for a fuel cell that is carried out at a temperature of 100 to 150 ℃. The method of claim 12, The hot rolling process is a method of manufacturing a membrane-electrode assembly for a fuel cell that is carried out under a pressure of 500 to 1000psi. The method of claim 12, Wherein said release film is selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyethylene terephthalate, and polyester. The method of claim 12, The content of the catalyst, binder, thickener and ionic liquid in the catalyst composition is 10 to 25 parts by weight of the binder, 75 to 150 parts by weight of the thickener and 20 to 50 parts by weight of the ionic liquid based on 100 parts by weight of the catalyst. Method of preparation. The method of claim 12, The thickener is selected from the group consisting of glycerol, dipropylene glycol, diethylene glycol, ethyl cellulose, hydroxypropyl cellulose, methyl cellulose and castor oil derivative (Castor oil derivative) . The method of claim 12, Wherein the ionic liquid comprises an organic cation. The method of claim 18, Wherein said organic cation is a cation of a heterocyclic compound. The method of claim 19, The heterocyclic compound is a method for producing a fuel cell membrane-electrode assembly comprising a hetero atom selected from the group consisting of N, O, S and combinations thereof. The method of claim 19, The heterocyclic compound is a method for producing a membrane-electrode assembly for a fuel cell comprising 1 to 4 hetero atoms. The method of claim 19, The cation of the heterocyclic compound is imidazolium (Imidazolium), pyrazolium, Tiazolium (Triazolium), Thiazolium (Thiazolium), Oxazolium, Pyridinium, Pyridazinium, Pyridazinium Method of producing a membrane-electrode assembly for a fuel cell which is a cation of a compound selected from the group consisting of Pyrimidinium, Pyrazinium or substituted compounds thereof. The method of claim 12, The ionic liquid includes an anion bonded to an organic cation, and the anion is a non-Lewis acid containing a polyvalent anion having a van der Waals volume of 100 이상의 ³ or more. The method of claim 23, wherein Wherein the ionic liquid is selected from the group consisting of the structural formula of Formula 1 to 9 fuel cell membrane-electrode assembly manufacturing method. [Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

(In Formulas 1 to 9, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are H, a halogen, or an alkyl group having 1 to 4 carbon atoms, or are bonded to each other to surround N. is to configure it or separate phenyl groups constituting the alkylene group, having 2 to 4 radicals to form the structure, and the alkyl, alkylene radicals or phenyl groups is _{^{F -, Cl -, CF 3}} -, SF 5 -, ^{_{CF 3 S -, (CF 3}} ) 2 CHS - and (CF _{3) 3} CS ^- as can be substituted with electron withdrawing selected from the group consisting of, and X ^- is an anion polyhydric having a van der Waals volume exceeding 100Å ³ It is a non-Lewis acid containing The method of claim 8, Wherein X ^- is ^{_{CF 3 CO 2 -, CF 3}} SO 3 -, BF 4 -, PF 6 -, - O- (SO 2 R), - N- (SOR) 2, - C- (SO 2 R) 3 ^{_{, BR 4 -, PR 6 -}} , bis (perfluoroethyl sulfonyl) imide _{(N (C 2 F 5 SO} 2) 2 -, Beti), ( methylsulfonyl-trifluoromethyl) bis imide) (N ^{_{(CF 3 SO 2) 2 -}} , Im), tris (trifluoromethyl sulfonyl _{methide) (C (CF 3 SO 2} ) 2 -, Me), trifluoromethane sulfonimide, trifluoromethyl sulfonic Nate already-methyl-de, trifluoromethyl sulfonate, AsF ₆ ^-, ClO ₄ ^-, and will be selected from the group consisting of a combination thereof, wherein R is an alkyl group of a hydrogen, 1 to 12 carbon atoms, a hydroxy group, an alkoxy group having 1 to 6 carbon atoms A method for producing a membrane-electrode assembly for a fuel cell, which is from the group consisting of a group and a combination thereof. The method of claim 12, Wherein the catalyst composition has a viscosity of 500 to 7000 cps. The method of claim 12, After removing the porous release film from the catalyst layer transferred to the polymer electrolyte membrane, Further performing a step of acid-treating the membrane-electrode assembly, wherein the polymer electrolyte membrane is a fuel cell membrane in which the H of the cation exchanger is substituted with one selected from the group consisting of Na, K, Li, Cs and tetrabutylammonum- Method of manufacturing the electrode assembly. At least one electricity generating unit comprising the membrane-electrode assembly and the separator of any one of claims 1 to 11 for generating electricity through the oxidation reaction of the fuel and the reduction reaction of the oxidant; A fuel supply unit supplying fuel to the electricity generation unit; And An oxidant supply unit for supplying an oxidant to the electricity generating unit Fuel cell system.

Images