KR101561101B1 - Polymer catalyst Slurry composition, porous electrodes produced thereby, membrane-electrode assembly comprising the porous electrodes, and method for the MEA - Google Patents

Abstract

The present invention relates to a polymeric catalyst slurry composition for an energy storage device, a porous electrode comprising a catalyst layer formed from the composition, a membrane-electrode assembly comprising the same, and a method for producing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a polymer catalyst slurry composition, a porous electrode, a membrane-electrode assembly including the same, and a method of manufacturing the same,

The present invention relates to a polymeric catalyst slurry composition for an energy storage device, a porous electrode comprising a catalyst layer formed from the composition, a membrane-electrode assembly comprising the same, and a method for producing the same.

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

This fuel cell is a clean energy source that can replace fossil energy. It has the advantage of being able to output a wide range of output by stacking the unit cells by stacking them. The fuel cell has an energy density of 4 to 10 times So that it is attracting attention as a compact and portable portable power source.

Particularly, typical examples of the polymer electrolyte fuel cell include a polymer electrolyte membrane fuel cell (PEMFC), a unitized regenerative fuel cell (URFC), a direct oxidation fuel cell (direct oxidation fuel cell) . Direct methanol fuel cell (DMFC) in the case of using methanol as the fuel in the direct oxidation type fuel cell, direct ethanol fuel cell in the case of using ethanol, direct direct methanol fuel cell in the case of using formic acid, It is called a direct formic acid fuel cell.

The polymer electrolyte fuel cell has advantages of high energy density and high output. However, in order to produce hydrogen which is a fuel gas, attention has to be paid to the handling of hydrogen gas, and a fuel for reforming methane, methanol and natural gas There is a problem that an additional facility such as a reforming device is required.

On the other hand, the direct oxidized fuel cell and the integral regenerative fuel cell have an advantage that the fuel is easy to handle and the fuel reforming device is not required.

In such a fuel cell system, the stack for generating electricity may include several unit cells made of a membrane-electrode assembly (MEA) and a separator (also referred to as a bipolar plate) To several tens of layers.

The membrane-electrode assembly is provided with an anode electrode (also referred to as a "fuel electrode" or an "oxidizing electrode") and a cathode electrode (also referred to as an "oxidizing electrode" or "a reducing electrode") sandwiching a polymer electrolyte membrane containing a proton- ) Are located in the vicinity of the surface of the substrate.

Although the membrane-electrode assembly having the above structure is mainly used, it is accompanied with problems of deterioration of the performance of the unit cell and the stack due to the porous collapse of the electrode.

In order to solve the above-described problems, the present inventors have made efforts to develop the porous catalyst layer forming technique and have completed the present invention.

Accordingly, an object of the present invention is to provide a polymer catalyst slurry composition having a composition maximizing viscosity for facilitating electrode production by facilitating formation of pores in a catalyst layer included in an electrode for increasing an electrochemically active surface area and optimizing a coating operation .

Another object of the present invention is to provide a porous electrode having an electrode structure capable of not only improving hydrogen ion conductivity when driving an energy storage device but also removing generated water by including a porous catalyst layer.

It is another object of the present invention to provide a method of manufacturing a membrane electrode assembly with improved productivity by applying a polymer catalyst slurry composition which is easy to control viscosity.

Still another object of the present invention is to provide a membrane electrode assembly and an energy storage device which can realize excellent cell performance by including a porous electrode.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above-mentioned object, the present invention provides a polymer catalyst slurry composition comprising a catalyst, an ionomer, a dispersion solvent and a water-soluble low molecule.

In a preferred embodiment, the ionomer is contained in an amount of 10 to 500 parts by weight per 100 parts by weight of the catalyst, 10 to 500 parts by weight of the dispersion solvent, and 1 to 500 parts by weight of the water soluble low molecule per 100 parts by weight of the ionomer .

In a preferred embodiment, the polymeric catalyst slurry composition has a viscosity of 1200 cps or more.

In a preferred embodiment, the water soluble low molecular weight is at least one selected from the group consisting of polyethylene glycol, polytetramethylene glycol, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polypropylene glycol and chitosan.

In a preferred embodiment, the dispersing solvent is selected from the group consisting of distilled water, ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, methanol, dimethyl formamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, . ≪ / RTI >

The present invention also relates to an electrode substrate serving as a support; And a porous catalyst layer comprising a water-soluble low molecular material or a plurality of pores formed on the electrode substrate.

In a preferred embodiment, the porous catalyst layer is formed by applying any one of the polymer catalyst slurry compositions described above.

In a preferred embodiment, the apparatus further comprises a microporous layer formed between the electrode substrate and the porous catalyst layer.

In a preferred embodiment, it further comprises an outer ionomer layer formed on the porous catalyst layer.

The present invention also provides a method for producing a polymer catalyst slurry composition, comprising: preparing a polymer catalyst slurry composition comprising a catalyst, an ionomer, a dispersion solvent, and a water-soluble low molecule; Applying the polymeric catalyst slurry composition to an electrode substrate to form a catalyst layer; Drying the catalyst layer to form an electrode; And preparing a membrane-electrode assembly by bonding the prepared electrode to both the anode electrode and the cathode electrode on both surfaces of the polymer electrolyte membrane to produce a membrane-electrode assembly.

In a preferred embodiment, the method further comprises removing water soluble low molecular weight components of the catalyst layer contained in the membrane-electrode assembly produced.

In a preferred embodiment, the step of forming the electrode further comprises forming an outer ionomer layer on the catalyst layer after the catalyst layer is dried by applying a liquid polymer having the same or similar characteristics as the electrolyte membrane .

In a preferred embodiment, the method further includes the step of forming a microporous layer for enhancing the reactant diffusion effect before forming the catalyst layer on the electrode substrate.

In a preferred embodiment, the step of removing water-soluble low molecular weight components of the catalyst layer may be performed by impregnating the membrane-electrode assembly with distilled water or maintaining the flow rate at 1 to 1000 cc / min.

In a preferred embodiment, the polymer catalyst slurry composition contains 10 to 500 parts by weight of the ionomer per 100 parts by weight of the catalyst, 10 to 500 parts by weight of the dispersion solvent, and the water- 500 parts by weight.

In a preferred embodiment, the method further comprises stabilizing the polymeric catalyst slurry composition to a viscosity of at least 1200 cps.

In a preferred embodiment, the water soluble low molecular weight is at least one selected from the group consisting of polyethylene glycol, polytetramethylene glycol, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polypropylene glycol and chitosan.

The present invention also provides a porous membrane-electrode assembly, which is produced by any one of the above-described production methods, and comprises a porous catalyst layer comprising a water-soluble low molecular material or a plurality of pores.

In a preferred embodiment, the porous catalyst layer included in the electrode of the porous membrane-electrode assembly includes at least one of Pt, Pt / Ir, Pt / Ru, Pt / W, Pt / Ni, Pt / Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni, Pt / Ru / Sn, W, or a combination thereof.

The present invention also provides an energy storage device comprising the above-described porous membrane-electrode assembly.

In a preferred embodiment, the energy storage device is a fuel cell.

First, the polymer catalyst slurry composition of the present invention facilitates the formation of pores of the catalyst layer included in the electrode to increase the electrochemically active surface area, optimizes the coating operation by maximizing the viscosity, and facilitates electrode production .

Further, according to the porous electrode of the present invention, by including the porous catalyst layer, not only the proton conductivity is improved but the generated water can be removed when the energy storage device is driven.

In addition, according to the method for producing a membrane electrode assembly of the present invention, productivity is improved automatically by applying a high-viscosity polymer catalyst slurry to an electrode substrate.

In addition, according to the membrane electrode assembly and the energy storage device of the present invention, excellent cell performance can be realized by including the porous electrode.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a schematic view showing the structure of an electrode and a membrane-electrode assembly according to an embodiment of the present invention.
2 is a schematic diagram showing the overall configuration of a battery system according to another embodiment of the present invention.
3 is an exploded perspective view showing a stack of a battery system according to another embodiment of the present invention.
FIG. 4A is a graph illustrating current density of a fuel cell including the porous membrane-electrode assembly of the present invention, and FIG. 4B is a graph illustrating current density in an electrolytic cell mode.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term, not on the name of a simple term, but on the entire contents of the present invention.

Where a section of a layer, film, area, plate, or the like is referred to as being "on" another section, unless stated otherwise in this specification, this includes not only the section "directly above" another section, do.

As used herein, the term "porous" means not only a structure in which a plurality of pores are already formed, but also a concept including a preliminary state in which a plurality of pores can be formed in use in a finished product.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The present invention relates to a polymer catalyst for forming an electrode catalyst layer having a composition capable of easily forming pores in a catalyst layer included in an electrode so as to increase the electrochemically active surface area, A slurry composition, a porous electrode having a porous catalyst layer formed of the slurry composition, a porous membrane electrode assembly including the porous electrode, a method of producing the conjugate, and a porous membrane electrode assembly.

First, the polymeric catalyst slurry composition of the present invention comprises a catalyst, an ionomer, a dispersion solvent and a water-soluble low molecule.

Here, the polymer catalyst slurry composition may contain 10 to 500 parts by weight of ionomer per 100 parts by weight of catalyst, 10 to 500 parts by weight of dispersion solvent, and 1 to 500 parts by weight of water soluble low molecular weight per 100 parts by weight of ionomer.

The catalyst may participate in the reaction of the battery, and any catalyst that can be used as the catalyst may be used. Specifically, a metal catalyst, more specifically, a platinum catalyst may be used. Platinum-based catalysts include platinum, iridium, ruthenium, osmium, platinum-ruthenium alloys, platinum-iridium alloys, platinum-osmium alloys, platinum- Fe, Co, Ni, Cu, Zn, Sn, Mo, W, Rh, Ru, or a combination thereof) or a combination thereof.

As a specific example of the catalyst used in the present invention, Pt, Pt / Ir, Pt / Ru, Pt / W, Pt / Ni, Pt / Sn, Pt / Mo, Pt / Pd, Pt / / Co, Pt / Ru / W, Pt / Ru / Mo, Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni, Pt / Ru / Sn / W, will be.

The catalyst may be used as the catalyst itself, or may be supported on a carrier. The carrier may be a carbonaceous material such as graphite, denka black, ketjen black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nano ball, graphene, heat treated graphite, activated carbon, , And inorganic fine particles such as alumina, silica, zirconia, and titania may be used, but carbon-based materials are generally used.

Particularly, when a noble metal supported on a support is used as a catalyst, commercialized commercial products may be used, or a noble metal may be supported on a support. Since the process of supporting the noble metal on the carrier is well known in the art, a detailed description thereof will not be given in the present specification, and is easily understood by those skilled in the art.

The ionomer contained in the polymer catalyst slurry composition of the present invention may be a polymer resin having hydrogen ion conductivity. Specifically, it may be a polymer resin having sulfonic acid group, carboxylic acid group, phosphoric acid group, phosphonic acid group and derivatives thereof Can be used as the polymeric resin. More specifically, examples of the polymer include fluorine-based polymers (Nafion, asiflex, and polymers), benzimidazole polymers, polyimide polymers, polyamide polymers, polyarylene ether polymers, polyetherimide polymers, Based polymers, polyether sulfone-based polymers, polyether-ketone-based polymers, polyether-ether ketone-based polymers, polyphosphazene-based polymers, polystyrene-based polymers, radially-grafted FEP-g-polystyrene grafted PVDF-g-polystyrene, and radiation-grafted FEP-g-polystyrene, radiation-grafted PVDF-g-polystyrene, and polyphenylquinoxaline- And more specifically, tetrafluoroethylene containing poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), sulfonic acid group, and Poly (2,2'-m-phenylene) -5,5'-bibenzimidazole copolymer, fluorinated polyether ketone, aryl ketone, poly (2,2'- -5,5'-bibenzimidazole] and poly (2,5-benzimidazole) can be used.

Particularly, in the polymer resin having hydrogen ion conductivity, H may be substituted with Na, K, Li, Cs or tetrabutylammonium in the cation exchanger at the side chain terminal. In the case of replacing H with Na in the ion exchange group at the side chain terminal, NaOH is substituted in the preparation of the catalyst composition and tetrabutylammonium hydroxide is used in the case of replacing with tetrabutylammonium, and K, Li or Cs is also substituted with a suitable compound . ≪ / RTI > Since this substitution method is well known in the art, a detailed description thereof will be omitted in this specification.

The ionomer may be used singly or in the form of a mixture, and may optionally also be used together with a nonconductive compound for the purpose of further improving the adhesion to the polymer electrolyte membrane. The amount used may be adjusted to suit the purpose of use.

The dispersion solvent contained in the polymer catalyst slurry composition of the present invention may be an alcohol such as ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol or methanol, distilled water, dimethyl formamide, dimethylacetamide, dimethylsulfoxide, N- Methylpyrrolidone, tetrahydrofuran, and the like.

The water-soluble low molecular weight contained in the polymer catalyst slurry composition of the present invention may be one or more selected from the group consisting of polyethylene glycol, polytetramethylene glycol, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polypropylene glycol and chitosan . In other words, the polymer catalyst slurry composition of the present invention maximizes the viscosity of the polymer catalyst slurry to be higher than 1200 cps by including a water-soluble low molecular compound unlike the slurry composition composed of the ionomer and the catalyst for forming the catalyst layer of the conventional battery, And the water soluble low molecular weight contained in the catalyst layer is removed in the electrode manufacturing process or the membrane-electrode assembly manufacturing process of forming the catalyst layer with the polymer catalyst slurry composition of the present invention.

In addition, even when the electrode is manufactured without removing the water-soluble low molecule, the water-soluble low molecular weight is removed by the water generated in the fuel cell mode operation including the membrane-electrode assembly formed with the manufactured electrode, thereby providing the porous electrode structure .

Next, the porous electrode of the present invention comprises an electrode substrate serving as a support; And a porous catalyst layer formed on the electrode substrate.

As shown in FIG. 1, the cathode electrode and the anode electrode may each include an electrode substrate (1) and a catalyst layer (3), and the catalyst layer (3) may be formed on the electrode substrate (1).

The electrode substrate (1) uses a conductive substrate, and specific examples thereof include carbon paper, carbon cloth, carbon felt, or metal cloth (a porous film or polymer composed of a metal in a fibrous state) A metal film formed on the surface of the fabric formed of fibers) may be used, but is not limited thereto.

The electrode substrate (1) may be a conductive substrate and a fluorine resin. The conductive base material may be used by reprocessing with a fluorine-based resin to prevent the reactant diffusion efficiency from being lowered due to water generated when the fuel cell is driven.

Examples of the fluorinated resin to be used include polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride alkoxy vinyl ether, fluorinated Ethylene propylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, or copolymers thereof.

The catalyst layer (3) formed on the electrode substrate (1) can be formed by applying the polymer catalyst slurry composition onto the electrode substrate (1). The coating process may be performed by a screen printing method, a spray coating method, a coating method using a doctor blade, a brushing method, or the like, depending on the viscosity of the polymer catalyst slurry composition, but is not limited thereto.

As described above, the catalyst layer (3) may be formed of a polymer catalyst slurry composition and may include a plurality of pores formed at a portion where the water-soluble low-molecular substances are present by removing water-soluble low-molecular substances contained in the catalyst layer, or may contain water-soluble low-molecular substances. On the other hand, even when the electrode is manufactured without removing the water-soluble low molecular weight, the water-soluble low molecular weight is removed by the water generated in the fuel cell mode operation, and consequently, the porous electrode structure can be provided.

At least one of the cathode electrode and the anode electrode may further include a microporous layer (2) for enhancing a reactant diffusion effect, as shown in FIG.

The microporous layer (MPL, 2) is generally composed of a conductive powder having a small particle diameter such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotube, carbon nanowire, A carbon nano-horn, a carbon nano ring, graphene, or a combination thereof.

That is, the microporous layer (MPL, 2) can be formed by coating a composition containing the conductive powder, the binder resin and the solvent on the electrode substrate.

Examples of the binder resin include fluorine-based polymers (Nafion, Asiflex, Flemion), polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl Fluoride, alkoxyvinyl ether, polyvinyl alcohol, cellulose acetate, copolymers thereof and the like can be used. Examples of the solvent include alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol and methanol, distilled water, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone and tetrahydrofuran.

The coating process may be performed by a screen printing method, a spray coating method, a coating method using a doctor blade, a brushing method, or the like, depending on the viscosity of the composition, but is not limited thereto.

Further, in order to manufacture an electrolyte membrane-electrode assembly (MEA) by a hot press method after the catalyst layer for causing the electrochemical reaction as shown in FIG. 1 is manufactured, In order to reduce the interfacial resistance and to improve the ionic conductivity, it is possible to produce an electrode in which an ionomer layer (7) is further formed on the catalyst layer by applying an ionomer, which is a liquid polymer having the same or similar properties as those of the polymer electrolyte membrane, The ionomer used to form the external ionomer layer (7) is as described above. The ionomer solution manufacturing process for reducing the interfacial resistance can be performed by, for example, mixing IPA, distilled water and a certain amount of ionomer solution with each other and stirring for one hour in an ultra sonic (sonicator) Thereby forming an outer ionomer layer (7). The hydrogen ion conductivity can be improved through the external ionomer layer (7), the dispersibility of the catalyst can be improved, the electrode resistance can be reduced, and the adhesion of the catalyst layer can be improved.

When the catalyst layer (3) is formed on the electrode substrate (1) and the water soluble low molecular weight (4) contained in the catalyst layer (3) is removed, a porous electrode can be obtained. 1, a microporous layer (MPL) is formed on the electrode substrate (1) and then a catalyst layer (3) is formed. An external ionomer layer (7) is formed on the catalyst layer (3) And the water soluble low molecular weight (4) contained in the catalyst layer (3) may be removed to obtain the porous electrode. In addition, a porous electrode containing only one of the microporous layer (MPL, 2) or the external ionomer layer (7) may be produced.

Next, a method for manufacturing a porous membrane-electrode assembly according to the present invention comprises the steps of: preparing a polymer catalyst slurry composition comprising a catalyst, an ionomer, a dispersion solvent and a water-soluble low molecule; Applying a polymeric catalyst slurry composition to an electrode substrate to form a catalyst layer; Drying the catalyst layer to form an electrode; And forming the membrane-electrode assembly by bonding the prepared electrode to both the anode and cathode electrodes on both surfaces of the polymer electrolyte membrane. And optionally removing water-soluble low molecular weight components of the catalyst layer contained in the prepared membrane-electrode assembly. That is, as described above, the water-soluble low molecular weight of the catalyst layer included in the membrane-electrode assembly can be spontaneously dissolved by the water generated in the fuel cell mode operation, but the water-soluble low molecular weight of the catalyst layer is completely removed from the beginning to realize the porous electrode structure , It is possible to broaden the applicability.

The step of preparing the polymer catalyst slurry composition is carried out by dissolving the constituent materials contained in the above-mentioned polymer catalyst slurry composition in a content ratio.

The step of forming the catalyst layer can also be carried out using a coating process known to the prepared electrode substrate, as described above, for the polymer catalyst slurry composition.

In particular, the step of fabricating the electrode may further include forming a layer of an external ionomer as described above by applying a liquid polymer having the same or similar characteristics as the electrolyte membrane on the dried catalyst layer after the catalyst layer is dried.

The method may further include the step of forming a microporous layer for enhancing the reactant diffusion effect before forming the catalyst layer on the electrode substrate.

The polymer electrolyte membrane is prepared by preparing a polymer electrolyte membrane. The polymer electrolyte membrane has an ion exchange function of moving hydrogen ions produced in the catalyst layer of the anode electrode to the catalyst layer of the cathode electrode. Polymers can be used.

The membrane-electrode assembly can be manufactured by bonding an electrode having the above-described structure on both surfaces of a polymer electrolyte membrane prepared as shown in FIG. 1, with an anode electrode and a cathode electrode, respectively. In this case, the same material may be used for the anode electrode and the cathode electrode. However, in order to prevent the catalyst poisoning phenomenon due to carbon monoxide (CO) generated during the anode electrode reaction in the direct oxidation fuel cell, a platinum-ruthenium alloy catalyst Can be used as an anode electrode catalyst.

In the manufacture of the membrane-electrode assembly, the pressurization may be thermally pressurized at a predetermined time, temperature and pressure. Specifically at a time of 1 to 3600 seconds, at a temperature of 50 to 500 占 폚 and at a pressure of 1 to 5000 psi, more specifically a time of 60 to 300 seconds, a temperature of 100 to 200 占 폚, and a pressure of 100 to 1000 psi Pressure. ≪ / RTI > The temperature condition improves the flexibility of the polymer chain as the glass transition temperature range of the ionomer introduced into the polymer electrolyte membrane or the electrode layer, thereby enhancing the interfacial stability, that is, the adhesion between the membrane and the electrode, thereby contributing to stabilization of the cell performance. On the other hand, long pressurization time and high pressure may cause deterioration of cell performance by inducing an electrode structure which is detrimental to mass transfer by changing the morphology of the electrode catalyst layer.

The step of removing the water-soluble low molecular weight of the catalyst layer can be performed by impregnating the membrane-electrode assembly with distilled water or maintaining the flow rate at 1 to 1000 cc / min. The porous electrode morphology is maintained through the water- And facilitates the flow of the generated water and fuel, thereby contributing to the improvement of the cell performance.

Although the water-soluble low molecular weight contained in the catalyst layer may be removed after the membrane-electrode assembly is prepared as described above, the water-soluble low molecular weight contained in the catalyst layer may be removed during the preparation of the electrode, A conjugate may be produced.

As shown in FIG. 1, the cathode and anode electrodes positioned opposite to each other are GDL (1), MPL (2), and catalyst layer (3) [water soluble low molecular weight (4) , An ionomer and a catalyst (5)), and an outer ionomer layer (7), and is disposed between the cathode electrode and the anode electrode. Particularly, it can be seen that the water-soluble low molecular weight (4) is removed, and thus a large number of pores can be formed in the catalyst layer.

The fuel cell system 100 including the membrane-electrode assembly 132 described above with reference to Figs. 2 and 3 will be described. 2 and 3 show an example of the fuel cell system, but the present invention is not limited thereto.

2 and 3, a fuel cell system 100 according to an embodiment of the present invention includes a fuel supply unit 110 for supplying mixed fuel in which fuel and water are mixed, A stack 130 for generating an electric energy by causing the reformed gas to electrochemically react with the oxidizing agent, and a reforming unit 130 for converting the oxidizing agent into the reforming unit 120 and the stack 130, And an oxidizing agent supply unit 140 for supplying the oxidizing agent to the oxidizing agent supply unit 140.

The stack 130 includes a plurality of unit cells 131 for generating electrical energy by inducing an oxidizing / reducing reaction of the reforming gas supplied from the reforming unit 120 and the oxidizing agent supplied from the oxidizing agent supplying unit 140, Respectively.

Each unit cell 131 refers to a unit cell that generates electricity. The unit cell 131 includes a membrane electrode assembly (membrane electrode assembly) for oxidizing / reducing oxygen in the oxidant, a reformed gas containing the hydrogen gas, (Or a bipolar plate) for supplying the reforming gas containing the hydrogen gas and the oxidizing agent to the membrane electrode assembly 132 is referred to as a 'separator' .) ≪ / RTI > The separator 133 is disposed on both sides of the membrane-electrode assembly 132, centering on the membrane-electrode assembly 132. At this time, the separator located at the outermost side of the stack may be referred to as an end plate 133a in particular.

The end plate 133a of the separation plate 133 is provided with a first supply pipe 133a1 in the form of a pipe for injecting the reforming gas supplied from the reforming unit 120 and a pipe- A first discharge pipe 133a3 for discharging the remaining unreacted reformed gas to the outside in the plurality of unit cells 131 and a second discharge pipe 133a2 for discharging the remaining unreacted reformed gas to the outside, And a second discharge pipe 133a4 for discharging the remaining unreacted oxidant in the cell 131 to the outside.

Example

1. Preparation of cathode and anode catalyst slurry compositions

,Dupont사) 50 중량부 첨가하고, 수용성 저분자(폴리에틸렌글리콜)는 나피온 이오노머와 동일한 양을 투입하여 캐소드촉매슬러리조성물을 제조하였다. 이때 이오노머는 캐소드 내에서 20 중량%로 포함되었다. 촉매로서 Pt 블랙을 사용한 점을 제외하고는 캐소드촉매슬러리조성물의 제조 방법과 동일한 방법으로 애노드촉매슬러리조성물을 제조하였다. 촉매 슬러리조성물 제조시, 슬러리의 점도는 1200 cps 이상이 되도록 혼합과정에서 열을 가할 수 있다.As a catalyst, 100 parts by weight of a solvent in which water and isopropyl alcohol were mixed at a weight ratio of 10:80 per 100 parts by weight of Pt / Ir (weight ratio 85:15) black was added. As the ionomer, Nafion

, Dupont), and the water-soluble low molecular weight (polyethylene glycol) was added in the same amount as that of the Nafion ionomer to prepare a cathode catalyst slurry composition. At this time, the ionomer was contained in an amount of 20% by weight in the cathode. An anode catalyst slurry composition was prepared in the same manner as in the preparation of the cathode catalyst slurry composition except that Pt black was used as the catalyst. In preparing the catalyst slurry composition, the viscosity of the slurry may be increased to 1200 cps or more during the mixing process.

2. Electrode Manufacturing

The prepared anode and anode catalyst slurry compositions are applied to GDL and then an electrode catalyst layer is formed and dried in an oven maintained at 60 to 70 ° C. The dried electrode was further coated with an ionomer and dried in an oven maintained at 60 to 70 ° C to complete an electrode having an outer ionomer layer on the catalyst layer.

3. Porous membrane-electrode-junction fabrication

After the Nafion membrane was fixed between the completed positive and negative electrodes, the membrane-electrode assembly was prepared by setting the temperature of the hot press at 140 캜 and the pressure at 100 psi for 3 minutes. The membrane-electrode assembly thus prepared was mounted in a unit cell discharge kit, and distilled water was supplied to maintain the membrane-electrode assembly for 1 hour, and then the flow rate of 10 cc / min was maintained for 12 hours. The porous membrane-electrode-bonded body was prepared by removing the water-soluble low molecular weight in the electrode and forming the porosity of the electrode catalyst layer.

Comparative Example

Pt / Ir (weight ratio 85:15) black as a catalyst was added to a mixed solvent of water and isopropyl alcohol at a weight ratio of 10:80. 5% by weight of Nafion (Nafion®, Dupont) as an ionomer was added to the solvent to prepare a cathode catalyst slurry. At this time, the ionomer contained 20 wt% in the cathode electrode.

An anode catalyst slurry was prepared in the same manner as in the production of the cathode catalyst slurry except that Pt black was used as the catalyst.

Nafion was used as the polymer electrolyte membrane. The anode catalyst slurry was coated on one surface of the polymer electrolyte membrane and the anode catalyst slurry was coated on the other surface of the polymer electrolyte membrane, and a catalyst coated membrane (CCM) .

W1S 1005 manufactured by CeTech Co., Ltd. as an electrode substrate was placed on both surfaces of the catalyst coating film to prepare a comparative membrane-electrode assembly having an active area of 25 cm 2. At this time, the hot press was performed by setting the temperature at 140 캜 and the pressure at 500 psi for 3 minutes.

Experimental Example

The porous membrane-electrode assemblies prepared in the examples and the comparative membrane-electrode assemblies prepared in the comparative examples were fixed with a bipolar plate and an end plate to assemble the unit cells. Hydrogen at a cell temperature of 70 ° C. and humidified state was fed at a rate of 300 cc / min , Oxygen in a humidified state was supplied at 500 cc / min, and then 0.7 V was applied in the course of driving for 2 hours. The current density maintenance characteristics of the fuel cell were evaluated, and the cell performance results are shown in Figs. 4A and 4B.

FIG. 4A is a graph illustrating current density of a fuel cell including the porous membrane-electrode assembly of the present invention, and FIG. 4B is a graph illustrating current density in an electrolytic cell mode.

4A and 4B, it can be seen that the fuel cell including the porous membrane-electrode assembly maintains the current density under the low humidification condition, and thus it can be seen that the fuel cell having excellent performance can be realized.

As described above, the porous membrane-electrode assembly according to the present invention has a large number of pores in the catalyst layer, thereby facilitating the flow of water and fuel generated through the electrochemical reaction, thereby contributing to the cell performance improvement.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

100: fuel cell system 110: fuel supply unit
120: reforming section 130: stack
131: unit cell 132: membrane-electrode junction body
133: separating plate 134: end plate
133a1: first supply pipe 133a2: second supply pipe
133a3: First discharge pipe 133a4: Second discharge pipe
140: Air supply

Claims (21)

A catalyst, an ionomer, a dispersion solvent, and a water-soluble low molecule, and having a viscosity of 1200 cps or more.
The method according to claim 1,
Wherein the ionomer is contained in an amount of 10 to 500 parts by weight per 100 parts by weight of the catalyst, 10 to 500 parts by weight of the dispersion solvent is contained, and 1 to 500 parts by weight of the water soluble low molecule is contained per 100 parts by weight of the ionomer. Slurry composition.
delete The method of claim 1,
Wherein the water soluble low molecular compound is at least one selected from the group consisting of polyethylene glycol, polytetramethylene glycol, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polypropylene glycol and chitosan.
The method according to claim 1,
The dispersion solvent may be at least one selected from the group consisting of distilled water, ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, methanol, dimethyl formamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone and tetrahydrofuran Wherein the polymer catalyst slurry composition is a polymer catalyst slurry composition.
An electrode substrate serving as a support; And
And a porous catalyst layer formed on the electrode substrate, the porous catalyst layer comprising a water-soluble low molecular material or a plurality of pores,
Wherein the porous catalyst layer is formed by applying the polymeric catalyst slurry composition of any one of claims 1, 2, 4, and 5.
delete The method according to claim 6,
And a microporous layer formed between the electrode substrate and the porous catalyst layer.
The method according to claim 6,
And an outer ionomer layer formed on the porous catalyst layer.
Preparing a polymer catalyst slurry composition containing a catalyst, an ionomer, a dispersion solvent, and a water-soluble low molecule and having a viscosity of 1200 cps or more;
Applying the polymeric catalyst slurry composition to an electrode substrate to form a catalyst layer;
Drying the catalyst layer to form an electrode; And
And bonding the prepared electrode to both surfaces of the polymer electrolyte membrane with an anode electrode and a cathode electrode, respectively, to produce a membrane-electrode assembly.
11. The method of claim 10,
And removing the water-soluble low molecular weight of the catalyst layer included in the membrane-electrode assembly to produce a porous membrane-electrode assembly.
11. The method of claim 10,
Wherein the step of forming the electrode further comprises forming an outer ionomer layer by applying a liquid polymer having the same or similar characteristics to the electrolyte membrane on the catalyst layer after the catalyst layer is dried, - Method for manufacturing electrode assembly.
11. The method of claim 10,
Further comprising the step of forming a microporous layer for enhancing a reactant diffusion effect before forming a catalyst layer on the electrode substrate.
12. The method of claim 11,
Wherein the step of removing the water soluble low molecular weight of the catalyst layer is performed by impregnating the membrane-electrode assembly with distilled water or maintaining the flow rate at 1 to 1000 cc / min.
11. The method of claim 10,
The polymer catalyst slurry composition contains 10 to 500 parts by weight of the ionomer per 100 parts by weight of the catalyst, 10 to 500 parts by weight of the dispersion solvent, and 1 to 500 parts by weight of the water soluble low molecule per 100 parts by weight of the ionomer Wherein the porous membrane-electrode assembly is a porous membrane-electrode assembly.

delete 11. The method of claim 10,
Wherein the water soluble low molecular weight is at least one selected from the group consisting of polyethylene glycol, polytetramethylene glycol, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polypropylene glycol and chitosan. 18. The porous membrane-electrode assembly according to any one of claims 10 to 17, wherein the porous membrane-electrode assembly comprises a water-soluble low-molecular substance or a porous catalyst layer containing a plurality of pores.
19. The method of claim 18,
The porous catalyst layer included in the electrode of the porous membrane-electrode assembly may include Pt, Pt / Ir, Pt / Ru, Pt / W, Pt / Ni, Pt / Sn, Pt / Mo, Pt / Cr, Pt / Co, Pt / Ru / W, Pt / Ru / Mo, Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni, Pt / Ru / Wherein the porous membrane-electrode assembly comprises a catalyst selected from the group consisting of:
An energy storage device comprising the porous membrane-electrode assembly of claim 18.
21. The method of claim 20,
Wherein the energy storage device is a fuel cell.

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