KR100441376B1 - A very thin Composite membrane - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing polymer membrane capable of maintaining mechanical strength while having a thin thickness. The composite membrane for a fuel cell is constructed and supported by a repetitive and regular net-shaped micro lattice structure. The present invention relates to a composite membrane having a thin thickness with excellent performance and reliability of forming a polymer electrolyte membrane completely filled with an ion exchange material or an ion exchange resin in a structural frame, and a method of manufacturing the same.

The present invention provides a method of forming a mask pattern having a net shape on a substrate including a silicon material thin film or a silicon oxide thin film, and etching the mask patterned substrate to form a micro lattice structure on the thin film. Repeating the step of applying and drying the ion exchange resin mixture by a spray method so that the hole of the structure is completely filled with the ion exchange resin mixture, so that both sides of the micro lattice net in the composite membrane are ion exchange resin mixture. It is characterized by a structure that is completely covered with.

The present invention serves as a micro lattice structure composed of a double layer of silicon oxide / silicon material (single crystal silicon, polycrystalline silicon, episilicon), increases the resistance to dehydration of the polymer electrolyte membrane, and can be manufactured to a uniform thin thickness. As a result, it is possible to provide a composite membrane having a thin film having high performance and high reliability with uniform performance.

Description

A very thin composite membrane

The present invention relates to a composite membrane (membrane) that can increase the performance and reliability of the solid polymer electrolyte membrane of the fuel cell, and more specifically to form a net-like micro lattice structure to act as a reinforcing material And it relates to a reinforced membrane prepared by coating an ion exchange resin mixture thereon.

The composite membrane including the repetitive and regular mesh-like micro lattice structure has a uniform thickness and has the advantage of uniform current density distribution and mechanical strength, and can be manufactured in a thin thickness to reduce the resistance of the membrane and reduce material costs. Can be. In addition, by forming a silicon oxide layer in the mesh-like micro lattice structure to increase the dehydration resistance of the solid polymer electrolyte membrane to prevent the sudden drop in the ionic conductivity, a thin thickness that can improve the performance and reliability of the solid polymer electrolyte membrane To a composite membrane.

In the case of a fuel cell, a solid polymer electrolyte membrane with little consumption due to evaporation or electrolyte leakage is interposed, and hydrogen is separated into hydrogen ions and electrons at an anode, and hydrogen ions are cathode through the electrolyte membrane. Electrons are generated and combine with oxygen at the cathode surface to produce water.

The reaction scheme at the anode is shown in Scheme 1.

Scheme 1

Oxidation _{reaction: H 2 (g) → 2} H +2 e -

Scheme at the cathode is the same as in Scheme 2.

Scheme 2

Reduction reaction:

The overall scheme of the cell is shown in Scheme 3.

Scheme 3

Cell reaction:

In order to promote oxidation and reduction of the two electrodes, a catalyst layer using platinum or a platinum-ruthenium alloy is coated between the gas diffusion layer and the polymer electrolyte membrane. As in the reaction scheme, electricity, heat, and water are generated by the redox reaction. Water is generally removed by strongly flowing air toward the cathode in the form of water and steam.

The mechanism by which protons, such as hydrogen ions, travel through a solid polymer electrolyte membrane is known as follows.

Solid polymer electrolyte membranes are generally made of polymer materials with functional groups capable of cation exchange. Among functional groups capable of cation exchange, sulfonic acid groups are typical, and protons are attached to sulfonic anions as cations. If present, it becomes a proton exchange membrane and is present with water molecules to maintain high proton conductivity. In the presence of water molecules, the sulfonic acid groups attached to the membrane dissociate into sulfonic acid anions and protons, and move under the influence of concentration gradients and electric fields like protons in sulfuric acid solution electrolytes.

1 is a schematic cross-sectional view of a conventional fuel cell stack. The unit cell 101 that forms the basis of the fuel cell stack is composed of two electrodes, an anode 103 and a cathode 104 separated by a solid polymer electrolyte membrane 102, and two electrodes on the outer surface of the polymer electrolyte membrane ( 103 and 104 constitute a membrane electrode assembly (MEA) by hot pressing, and the membrane electrode assembly can supply hydrogen as a fuel and oxygen as a reducing agent and discharge water generated by a redox reaction. It is supported by the separating plate 106 in which the flow path 105 is formed. The gasket 107 is configured such that the gas or liquid supplied or discharged through the flow path 105 of the separation plate does not flow out, and the membrane electrode assembly (MEA), the separation plate 106 and the gasket 107 are formed. The unit cells 101 are stacked in series to obtain the required output, and a stack is formed by fixing with copper plates 108 at both ends as a means for fixing them.

The electrodes 103 and 104 are composed of a gas diffusion layer and a catalyst layer. The gas diffusion layer is positioned immediately after the separator plate 106 to supply fuel and air to the catalyst layer, and serves as a movement path for the generated electrons. ) Or carbon cloth.

The solid polymer electrolyte membrane 102 adjacent to the electrodes 103 and 104 should have a thickness of about 50 to 200 μm, have high ion conductivity, have no electronic conductivity, be dense and have no dimensional gas permeability, and have dimensional stability. . In addition, when dehydration, ionic conductivity rapidly decreases, so it must be resistant to dehydration, shape stability and mechanical strength by hydration, and stability to heat, redox reaction and hydrolysis.

Phenol-formaldehyde sulfonic acid membranes prepared by condensation of phenol sulfonic acid and formaldehyde in the US General Electric (GE), a polymer electrolyte membrane for fuel cells of the prior art, are well broken and demanded. There was a lack of hydrolytic stability. In addition, the divinyl-benzene crosslinked polystyrene sulfonic acid membrane has a disadvantage in that the membrane stability is drastically deteriorated at an operating temperature of 70 ° C. or higher, and the polytrifluorostyrene sulfonic acid membrane has poor mechanical properties. It has not been practical because of its disadvantages.

The development of perfluorinated polymers with superior thermal and chemical stability compared to the membranes described above has led to the commercialization of polymer electrolyte membranes such as Nafion (manufactured by Dupont, Inc.). It is a polymer having a sulfonic acid group substituted in its skeleton, and its equivalent weight is about 1000 ~ 1200, its film thickness is about 50 ~ 200㎛, its tensile strength is 2500psi, elongation is 150%, burst strength is 150psi. It is a polymer electrolyte membrane that exhibits excellent properties in terms of cotton, membrane and hydrogen and oxygen separator functions.

However, the combination of the ion exchange resin and the microporous medium having the non-conductive group, which can greatly increase the ionic conductivity by reducing the perfluorinated polymer film thickness and lowering the resistance of the membrane. There is a growing interest in reinforced polymer membranes.

U.S. Patent No. 5,547,551 discloses a polytetrafluo ethylene membrane, which is a microporous structure supported by polymer fibrils, to impregnate an ion exchanger to completely fill the micropore, thereby producing a gas. A method of producing a composite membrane having a film thickness of 25 μm or less by occlusive so as not to pass through is disclosed.

2 is a schematic cross-sectional view of a composite membrane of the prior art. As shown in FIG. 2, the ion exchange material 201 is formed on a porous polytetrafluo ethylene membrane 200 connected to fibrils, which serves as a support for maintaining sufficient mechanical strength at a thin thickness. Or ion exchange resin 201 is prepared.

However, in the case of using fibrils or polymer supports serving as supports of conventional reinforced polymer membranes, fibrils are formed and formed in a random structure, and thus, uniformity of polymer electrolyte membrane performance is locally obtained. There is still a problem that cannot be guaranteed, and that the resistance to dehydration cannot be enhanced during proton migration.

Therefore, there is a need for a composite membrane that has high ionic conductivity, which is an advantage of thin, reinforced polymer membranes, and can dramatically increase the uniformity of membrane performance and resistance to dehydration during proton migration even in the local region of the polymer electrolyte membrane.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a composite membrane for a fuel cell, it is composed and supported by a repetitive and regular net-shaped micro lattice structure connected to each other. The present invention provides a composite membrane having a thin thickness having excellent performance and reliability by forming a polymer electrolyte membrane by filling an ion exchange material or an ion exchange resin in a micropore. There is a purpose.

In addition, the mesh-like micro lattice structure, which serves as a support, is composed of a double layer of silicon oxide / silicon material (monocrystalline silicon, polycrystalline silicon, episilicon) to provide a composite membrane that increases resistance to dehydration of the polymer electrolyte membrane. have.

In addition, an object of the present invention is to provide a composite membrane having a thin thickness having a locally uniform performance by finely processing a thickness and a micropore of a mesh-like micro lattice structure serving as a support in units of several micrometers (μm).

It is an object of the present invention to form sub-micropores that connect adjacent micropores of a mesh-like micro lattice structure, which serves as a support, to uniformly distribute ion exchange materials.

1 is a schematic cross-sectional view of a conventional fuel cell stack.

2 shows a schematic cross section of a composite membrane of the prior art;

3 is a view showing a composite membrane composed of a micro lattice structure of the present invention.

4 is a view showing a manufacturing process of a composite membrane having a thin thickness according to an embodiment of the present invention.

5 is a view showing the concept of a micro lattice structure sub-micropore of the present invention.

According to a first aspect of the present invention for achieving the above object, in a composite membrane (membrane) used as a polymer electrolyte membrane of a fuel cell, a plurality of micropores are repeated in a lattice structure It has a net-shaped support formed regularly, and is formed by filling an ion exchange material or an ion exchange resin in a micropore of the support. A composite membrane having a thin thickness is provided.

According to another embodiment of the present invention, a mesh-like support in which the micropores of the lattice structure are formed is provided with a composite membrane composed of single-silicon, epitaxially grown silicon, or polycrystalline silicon.

According to another embodiment of the present invention, the grid-shaped support in which the micro holes of the lattice structure are formed is silicon oxide (SiO ₂ ) or silicon oxide / single crystal silicon, silicon oxide / episilicon, silicon oxide / polycrystalline silicon, It is provided with a composite membrane composed of either bilayer, which has increased resistance to dehydration.

According to another embodiment of the present invention, the silicon oxide is a silicon oxide (SiO ₂ ) prepared by thermal oxidation (SiO ₂ ), a silicon oxide prepared by PECVD method, an oxide using TEOS (tetraethylorthosilicate) as a source and TTIP There is provided a composite membrane, characterized in that any one of (titanium tetraisopropoxide).

According to another embodiment of the present invention, the mesh-like support on which the micro holes of the lattice structure are formed has a thickness of 1 μm or more and 50 μm or less. A composite membrane is provided, characterized in that the gap therebetween is 0.5 µm or more and 20 µm or less.

According to another embodiment of the present invention, the mesh-like support in which the micro holes of the lattice structure are formed is preferably 2 μm or more and 10 μm or less, and micropore diameter is preferably 1 μm or more and 5 μm or less. It is preferable that the space | interval between holes is 1 micrometer or more and 5 micrometers or less.

According to another embodiment of the present invention, the ion exchange resin filling the micropores is composed of an ion exchange resin mixture, wherein the ion exchange resin mixture is perfluorosulfonic acid / tetrafluoro There is provided a composite membrane comprising an ethylene (tetrafluoroethylene) copolymer resin.

According to another embodiment of the invention, the ion exchange resin mixture is a perfluorinated sulfonic acid resin (perfluorinated sulfonic acid resin), a perfluorinated carboxylic acid resin (polyfluorinated carboxylic acid resin), polyvinyl alcohol resin (polyvinyl alcohol Resin, divinyl benzene resin, and styrene-based polymer, a composite membrane is provided comprising any one or two or more.

According to the second aspect of the present invention, a plurality of lattice structures in a net-like support are filled with ion exchange resins in respective micropores, which are repeatedly and regularly formed. A method of manufacturing a composite membrane, the method comprising: forming a net-shaped mask pattern on a substrate including a silicon material thin film or a silicon oxide thin film, and etching the mask patterned substrate to form the net film Forming a micro hole in the lattice structure, removing and washing the mask pattern on the thin film, applying and drying an ion exchange resin mixture in the micro hole of the lattice structure, and drying the micro structure of the lattice structure Repeating the step of applying and drying the ion exchange resin mixture to completely fill the hole with the ion exchange resin mixture. However, there is provided a method of manufacturing a composite membrane having a thin thickness, characterized in that the structure of the both sides of the micro lattice net (net) in the composite membrane is covered with an ion exchange resin mixture.

According to another embodiment of the present invention, forming a net-shaped mask pattern on a substrate including a silicon material thin film or a silicon oxide thin film is a step of coating a photoresist on the substrate, the photoresist is The method may further include exposing the coated substrate, and developing and drying the substrate.

According to another embodiment of the present invention, dry etching is performed by using an ICP (Induced Coupled Plama) etching equipment when manufacturing micro holes of the lattice structure, and the sub-micropore is formed in the micro holes of the lattice structure. Provided is a method for producing a composite membrane, characterized in that forming a).

According to another embodiment of the present invention, the step of etching the mask patterned substrate to form a micro hole of the lattice structure in the thin film, by performing a wet etching in an etching solution (etchant) the inner wall of the micro hole of the lattice structure There is provided a composite membrane production method characterized in that the surface is inclined rather than vertical.

According to another embodiment of the present invention, the step of applying and drying the ion exchange resin mixture in the micropore of the micro lattice structure, it is preferable to perform the application of the ion exchange resin mixture using a spray coating method. .

According to another embodiment of the present invention, repeating the step of applying and drying the ion exchange resin mixture to completely fill the ion exchange resin mixture in the lattice micro-holes on one side of the thin film, the thin film on the substrate Separation, a method for producing a composite membrane having a thin thickness, characterized in that further comprising the step of applying, drying the ion exchange resin mixture on the other side of the thin film.

According to a third aspect of the present invention, there is provided a composite membrane having a thin thickness produced by the method described above.

According to the fourth aspect of the present invention, a membrane electrode assembly, a unit cell, a fuel cell stack, a fuel cell system or a sensor, etc., comprising a composite membrane manufactured by the method described above may be provided.

First, in order to assist the understanding of the invention, the effect of applying a composite membrane having a thickness of several tens of micrometers scales, which are connected to each other, serving as a support in a reinforced polymer membrane, is described in detail below.

The polymer electrolyte membrane for fuel cells absorbs a significant amount of water in its molecular superstructure during fuel cell operation. The water content of the polymer membrane affects the ionic conductivity, mechanical stability and gas separation ability of the membrane, and since the polymer membrane has anisotropy, the length expansion caused by hydration is different depending on the arrangement according to the manufacturing direction as well as the humidity of the membrane. Depending on the direction, not only the mechanical properties but also the ionic conductivity is more than doubled.

According to the present invention, a plurality of micro holes are formed in a lattice structure to form a net-like support which is formed repeatedly and regularly, and ion exchange material or ion exchange resin is formed in the micro holes. When forming a reinforced polymer membrane filled with exchange resin, a mesh-shaped support having a lattice-type micro hole can suppress uneven length expansion caused by the hydration of the polymer membrane and can control mechanical properties according to directions. It is possible to provide reliable composite membranes. In addition, the silicon oxide is formed on the support having the lattice micro holes to increase resistance to dehydration that may occur during operation of the fuel cell, thereby preventing a sudden decrease in ion conductivity.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, the composite membrane composed of a micro lattice structure of a double layer structure of silicon oxide / single crystal silicon will be described for the purpose of understanding the present invention, but the present invention is not limited to the fuel cell. Therefore, it is also possible to use a polymer electrolyte fuel cell (PEFC) in which a fuel is a gas and a direct methanol fuel cell (DMFC) in which a fuel is a liquid (methanol) in a fuel cell including a polymer membrane. Similar processing steps can be applied and used in electrodialysis as well as those skilled in the art without departing from the spirit and scope of the invention as set forth in the claims below. It is natural that various modifications and changes can be made to the composite membrane having a thin thickness according to the invention.

3 is a view showing a composite membrane composed of a micro lattice structure of the present invention. The ion exchange material 302 or the ion exchange resin 302 is completely filled in the micropores 301 of the repetitive and regular mesh-shaped grid support 300 connected to each other. A composite membrane having a thin thickness that is impregnated is prepared. In addition, as shown in the cross-section along the AA ′ cross-section, the microstructures of the mesh form a double layer of silicon oxide 303 / single crystal silicon 304 using the hydrophilicity of silicon oxide to enhance the resistance to dehydration of the polymer electrolyte membrane. Construct a grid structure. The mesh-like micro lattice structure can be made of single-silicon, epitaxially grown silicon and polysilicon, silicon oxide (SiO ₂ ), and silicon oxide / epic silicon, silicon oxide / polycrystalline It can also be produced in a double layer structure of silicon. Examples of the silicon oxide (SiO ₂ ) include silicon oxide prepared by thermal oxidation, silicon oxide prepared by plasma enhanced chemical vapor deposition (PECVD), oxide using TEOS (tetraethylorthosilcate) as a source, and TTIP (titaniumtetraisopropoxide). ).

The thickness 305 of the mesh-shaped micro lattice support 300 is characterized by being 1 μm or more and 50 μm or less, preferably 10 μm or more and 20 μm or less, and considering the thin film composite membrane of 2 μm or more and 10 μm or less. Most preferred.

The shape of the hole 301 of the micro lattice in which the ion exchange material 302 or the ion exchange resin 302 is filled is possible in various shapes such as a rectangle, a circle, a triangle, and a lozenge, and the hole 301 has a diameter of 0.5 μm or more. It is characterized by being 50㎛ or less, preferably 5㎛ 20㎛ or less, and considering the uniform mechanical properties required in the reinforced polymer membrane is most preferably 1㎛ 5㎛. In addition, the width 306 of one side of the micro lattice structure is characterized by being 0.5 µm or more and 50 µm or less, preferably 5 µm or more and 20 µm or less, and most preferably 1 µm or more and 5 µm or less.

The ion exchange resin completely covering the micro lattice hole and the frame is composed of an ion exchange resin mixture, in which a perfluorosulfonic acid / tetrafluoroethylene copolymer resin is dissolved in a solvent. Use in state. Examples of the solvent for dissolving the ion exchange resin include water, ethanol, propanol, butanol, methanol, a mixed solvent of the solvent, and the like. In addition, the ion exchange resin mixture is a perfluorinated sulfonic acid resin (perfluorinated sulfonic acid resin), a perfluorinated carboxylic acid resin (perfluorinated carboxylic acid resin), polyvinyl alcohol resin (polyvinyl alcohol resin), divinyl benzene resin ( Divinyl benzene resins and styrene-based polymers can be used in one or a combination of two or more.

4 is a view showing a manufacturing process of a composite membrane having a thin thickness according to an embodiment of the present invention.

A process of manufacturing a composite membrane by filling an ion exchange material into a micropore of a repetitive and regular net-shaped micro lattice structure is as follows. In operation 405, a mask pattern having a net shape is formed on the substrate including the silicon material thin film or the silicon oxide thin film. In step 410, the mask patterned substrate is etched to form a micro lattice structure in the thin film, and in step 415, the mask pattern on the thin film is removed and cleaned, and in step 420, ion exchange is performed in the micropore of the micro lattice structure. Applying and drying the material and repeating the step of applying and drying the ion exchange material to completely fill the pores of the micro lattice in step 425, so that the ions in the micro lattice net holes and framework in the membrane are repeated. Immerse and completely cover the exchange material. In addition, repeating the step of applying and drying the ion exchange material, the composite membrane having a thin thickness further comprising the step of separating the thin film from the substrate, applying and drying the ion exchange material on the other side of the thin film To prepare.

The forming of the net-shaped mask pattern of step 405 may include coating a photoresist on the substrate, exposing the photoresist-coated substrate, and developing and drying the substrate. Is done.

The step of forming a micro lattice structure on the thin film by etching the mask patterned substrate of step 410, characterized in that for performing dry etching by using an ICP (Induced Coupled Plama) etching equipment, dry etching with an ICP etching equipment Using the size effect, the sub-micropore is formed in a size of about 1/10 to 1/3 of the size of the hole diameter of the micro lattice structure. The pores allow for uniform application of the ion exchange material. 5 is a view showing the concept of a micro-lattice sub-micropore (500) of the present invention. As shown in the cross-section along the BB 'cross-section, the depth of the auxiliary hole due to the size effect in the dry etching is less than the depth of the micro lattice structure at the time of dry etching. It can be seen that the etched depth is small.

In another method of forming a micro lattice structure on the thin film by etching the mask patterned substrate of step 410, wet etching is performed in an etchant to obtain a gradient in which the inner wall surface of the micro lattice hole is not vertical. You can have it.

The step of applying and drying the ion exchange material or the ion exchange resin mixture in the micropore of the micro lattice structure of step 420 is to perform the application of the ion exchange resin mixture using a spray coating method, wherein the ion exchange used is The resin mixture contains a surfactant for interfacial stabilization of the micro lattice structure and the ion exchange resin mixture.

Hereinafter, a method of manufacturing a composite membrane having a thin thickness reinforced by a mesh-like micro lattice structure made of single crystal silicon will be described in detail.

First of all, to manufacture a mesh micro lattice structure, a photoresist AZ1518 (Clariant) was placed on a 4-inch silicon on glass (SOG) wafer with a silicon thickness of 20 µm and spin-coated for 3000 seconds at a rotation speed of 3000 rpm. After coating by rotating in a spin coater, the oven is baked at 95 ° C. for 30 minutes to remove excess water in the photoresist. The next step is to use a photomask patterned with a microgrid network pattern to expose the mask aligner at an energy density of about 20 mW / cm 2 for about 7-8 seconds, followed by a developer (AZ). 500 MIF developer, Clariant) dipped for 60 seconds. The developed substrate is preferably baked at 110 ° C. for 30 minutes in an oven.

The SOG wafer, which has undergone the mask pattern process as described above, was fabricated using an ICP (Induced Coupled Plasma) etching equipment (SLR-7701 ICP, manufactured by Plasma-Therm) to achieve a micro lattice hole depth of 20. Etch to be μm. In the process of ICP (Induced Coupled Plasma) etching, SF ₆ , the etching gas, is 100 sccm, Ar is 30sccm, the etching time is 7 seconds, and the deposition gas, C ₄ , is the deposition gas. F ₈ is 70 sccm, Ar is 30 sccm flow rate and deposition time is 5 seconds. The substrate plate power RF1 is 9W in the etching step and 1W in the deposition step, and the chamber coil power RF2 is preferably etched by applying 825W in both the etching and deposition steps.

In addition, the ashing process is carried out for 10 minutes in an asher to remove the mask pattern which has been subjected to the ICP etching process, and the photoridge is boiled for 10 minutes at 120 ° C. in 4: 1 sulfuric acid and hydrogen peroxide solution. After removing the test strip and washing with deionized water for about 10 minutes in a scrubber, it is preferable to remove the moisture by drying in a dryer at about 120 ℃ for about 20 minutes.

After fabricating the mesh-like micro lattice structure on a 4 inch silicon on glass (SOG) wafer having a silicon thickness of 20 μm, a solvent consisting of propanol, butanol, and methanol is prepared. A solution of Triton X100 (Rohm & Haas) solution (5%) was dissolved in a solution (95%) in which a perfluorosulfonic acid / tetrafluoroethylene copolymer resin was dissolved. The mixed ion exchange resin mixture is sprayed and applied using a spray equipment, and then dried by baking at 130 ° C. for 1 minute. The application and drying process of the ion exchange resin mixture is repeated three times, and the micro lattice hole and the frame are completely covered with the ion exchange resin mixture to be impregnated. In addition, after dipping in an isopropanol solution for 5 minutes to remove the surfactant, washed with deionized water and dried at room temperature.

Apply the ion exchange resin mixture thinly on the surface of the SOG wafer prepared by filling the hole of the micro lattice structure with the ion exchange resin mixture in the unit of several micrometers using a spray equipment, and then bake at 130 ° C. for 1 minute. ) And dry.

In the next step, the glass part of the SOG wafer is mostly removed by lapping equipment, and then wet-etched in a 10: 1 HF solution for 1 minute to completely remove the glass part. The ion exchange resin mixture was applied to the other side of the frame of the micro lattice structure thus prepared by using a spray device, and then dried by baking at 130 ° C. for 1 minute and then isopropanol After immersing in (isopropanol) solution for 3 minutes to remove the surfactant, the composite membrane having a thin thickness was prepared by hydrating by breaking for 10 minutes under 1 atm of deionized water.

A method for producing a composite membrane having a thin thickness reinforced by a mesh-like micro lattice structure composed of a double layer of silicon oxide / monocrystalline silicon is as follows.

First, spin-coating machine was used to fabricate photoresist AZ1518 (Clariant) on a 4-inch silicon on insulator (SOI) wafer with a silicon thickness of 20 µm to produce a mesh-shaped microgrid structure. After coating by rotating in a spin coater, the oven is baked at 95 ° C. for 30 minutes to remove excess water in the photoresist. The next step is to use a photomask patterned with a microgrid network pattern to expose the mask aligner at an energy density of about 20 mW / cm 2 for about 7-8 seconds, followed by a developer (AZ). 500 MIF developer, Clariant) dipped for 60 seconds. The developed substrate is preferably baked at 110 ° C. for 30 minutes in an oven.

The SOI wafer, which has undergone a mask pattern process as described above, was fabricated using an ICP (Induced Coupled Plasma) etching equipment (SLR-7701 ICP, manufactured by Plasma-Therm) to achieve a micro lattice hole depth of 20. Etch to be μm. In the process of ICP (Induced Coupled Plasma) etching, SF ₆ , the etching gas, is 100 sccm, Ar is 30sccm, the etching time is 7 seconds, and the deposition gas, C ₄ , is the deposition gas. F ₈ is 70 sccm, Ar is 30 sccm flow rate and deposition time is 5 seconds. The substrate plate power RF1 is 9W in the etching step and 1W in the deposition step, and the chamber coil power RF2 is preferably etched by applying 825W in both the etching and deposition steps.

In addition, the ashing process is carried out in an asher for 10 minutes to remove the mask pattern which has been subjected to the ICP etching process, and the photoridge is boiled at 120 ° C. for 10 minutes in a 4: 1 sulfuric acid and hydrogen peroxide solution. After removing the test strip and washing with deionized water for about 10 minutes in a scrubber, it is preferable to remove the moisture by drying in a dryer at about 120 ℃ for about 20 minutes.

After fabricating a mesh-like micro lattice structure on a 4 inch silicon on insulator (SOI) wafer having a silicon thickness of 20 μm, the silicon oxide film is deposited to a thickness of 0.4 μm by a plasma enhanced chemical vapor deposition (PECVD) method. .

Perfluorosulfonic acid / tetrafluoroethylene in a solvent consisting of propanol, butanol and methanol on a micro lattice framework composed of a double layer of silicon oxide / monocrystalline silicon as described above. ) Spray the ion exchange resin mixture made by mixing Triton X100 (Rohm & Haas Co., Ltd.) solution (5%) with a solution of copolymer resin (95%) using a spray equipment. After coating, it is dried by baking at 130 ° C. for 1 minute. The application and drying process of the ion exchange resin mixture is repeated three times, and the micro lattice hole and the frame are completely covered with the ion exchange resin mixture to be impregnated. In addition, the solution is immersed in an isopropanol solution for 5 minutes to remove the surfactant, washed with deionized water and dried at room temperature.

Apply the ion exchange resin mixture thinly on the surface of the SOI wafer prepared by filling the micro lattice structure hole with the ion exchange resin mixture in the unit of several micrometers using a spray equipment, and then bake at 130 ° C. for 1 minute. ) And dry.

In the next step, the substrate silicon portion of the SOI wafer was removed by lapping equipment, and then wet-etched in a KOH solution at 80 ° C. for 1 minute to completely remove the substrate silicon portion, followed by a 10: 1 HF solution. Remove the insulator of the SOI. The ion-exchange resin mixture was applied to the other side of the frame of the micro lattice structure thus prepared by using a spray equipment in a few micrometers, and then baked and dried by baking at 130 ° C. for 1 minute and isopropanol ( isopropanol) soaked for 3 minutes to remove the surfactant, and then hydrated by deionized water at 1 atm for 10 minutes to prepare a composite membrane having a thin thickness.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a composite membrane for a fuel cell, wherein an ion exchange material or an ion exchange resin is filled in a frame reinforced with a repetitive and regular net-shaped micro lattice structure. By forming a polymer electrolyte membrane, the composite membrane has a uniform thickness and has an advantage of uniform current density distribution and mechanical strength. A silicon oxide layer is further formed on the mesh-like micro lattice structure to increase dehydration resistance of the polymer electrolyte membrane. It is possible to prevent sudden fluctuations in ion conductivity that may occur during operation of the fuel cell.

Since the thickness of the micro lattice structure and micropores are finely processed in units of several micrometers (μm), the polymer electrolyte membrane can be manufactured to a thickness of 5 μm or more and 30 μm or less, thereby reducing the membrane resistance while maintaining the mechanical strength of the polymer membrane As a result, a composite membrane having a thin thickness having a locally uniform performance can be realized, thereby providing a high performance and highly reliable polymer electrolyte membrane.

Claims (36)

In a composite membrane used as a polymer electrolyte membrane of a fuel cell, A plurality of micropores have a net-like support formed in a lattice structure and are repeatedly and regularly formed, and an ion exchange material or an ion exchange resin is formed in the micropores of the support. A composite membrane having a thin thickness, characterized in that formed by filling (ion exchange resin). The composite membrane according to claim 1, wherein the mesh support in which the micro holes of the lattice structure are formed is made of single crystal silicon. The composite membrane of claim 1, wherein the mesh support in which the micro holes of the lattice structure is formed is made of epitaxially grown silicon. The composite membrane according to claim 1, wherein the network support in which the micro holes of the lattice structure are formed is made of polycrystalline silicon. The composite membrane according to claim 1, wherein the support having a mesh shape in which the micro holes of the lattice structure are formed is made of silicon oxide. The composite membrane according to claim 1, wherein the mesh support having the lattice structure micro holes is formed of a double layer of silicon oxide and single crystal silicon. The composite membrane of claim 1, wherein the mesh support having the lattice-shaped micro holes is formed of a double layer of silicon oxide and episilicon. The composite membrane according to claim 1, wherein the mesh-like support on which the micro holes of the lattice structure are formed is composed of a double layer of silicon oxide and polycrystalline silicon. Of claim 5 to 8 according to any one of claim wherein the silicon oxide constituting the support of the reticular which the micro-holes of the grid structure forming the thermal oxidation a silicon dioxide prepared by _{(thermal oxidation) (SiO 2)} , PECVD A composite membrane having a thin thickness, characterized in that any one of a silicon oxide prepared by the method, an oxide using TEOS (tetraethylorthosilicate) as a source and titanium tetraisopropoxide (TTIP). The composite membrane according to claim 1, wherein the support having a mesh shape in which the micro holes of the lattice structure is formed has a thickness of 1 µm or more and 50 µm or less. The composite membrane according to claim 1, wherein the web-like support in which the micropores of the lattice structure are formed has a thickness of 10 µm or more and 20 µm or less. The composite membrane according to claim 1, wherein the web-like support in which the micro holes of the lattice structure are formed has a thickness of 2 µm or more and 10 µm or less. The composite membrane according to claim 1, wherein the diameter of the micropores formed in the network support is 0.5 µm or more and 50 µm or less. The composite membrane according to claim 1, wherein the diameter of the micropores formed in the mesh support is 5 µm or more and 20 µm or less. The composite membrane according to claim 1, wherein the diameter of the micropores formed in the mesh support is 1 µm or more and 5 µm or less. The composite membrane according to claim 1, wherein an interval between the micro holes formed in the network support is 0.5 µm or more and 20 µm or less. The composite membrane according to claim 1, wherein an interval between the micro holes formed in the mesh support is 5 µm or more and 10 µm or less. The composite membrane according to claim 1, wherein an interval between the micro holes formed in the mesh support is 1 µm or more and 5 µm or less. The composite membrane of claim 1, wherein the ion exchange resin filling the micropores is composed of an ion exchange resin mixture. 20. The composite membrane of claim 19, wherein the ion exchange resin mixture comprises a perfluorosulfonic acid / tetrafluoroethylene copolymer resin. 20. The composite membrane according to claim 19, wherein the ion exchange resin mixture is formed by dissolving an ion exchange resin in any one of water, ethanol, propanol, butanol, methanol, and a mixed solvent of the solvent. . The method of claim 19, wherein the ion exchange resin mixture is a perfluorinated sulfonic acid resin (perfluorinated sulfonic acid resin), perfluorinated carboxylic acid resin (polyfluorinated carboxylic acid resin), polyvinyl alcohol resin (polyvinyl alcohol resin), A composite membrane having a thin thickness comprising any one or two or more kinds of divinyl benzene resin and styrene-based polymer. A composite membrane is filled with ion exchange resin in each of the micropores, which are formed in a lattice structure and are repeatedly and regularly formed in a net-like support. In the manufacturing method, Forming a net-shaped mask pattern on a substrate including a silicon material thin film or a silicon oxide thin film; Etching the mask patterned substrate to form micro holes in a lattice structure in the thin film; Removing and cleaning the mask pattern on the thin film; Applying and drying an ion exchange resin mixture into the micropores of the lattice structure; And repeating the step of applying and drying the ion exchange resin mixture so that the ion exchange resin mixture is completely filled in the micro-pores of the lattice structure. 24. The method of claim 23, wherein forming a net mask pattern on the substrate including the silicon material thin film or the silicon oxide thin film, Coating a photoresist on the substrate; Exposing the photoresist coated substrate; Developing a composite membrane having a thin thickness, characterized in that it further comprises the step of developing, drying the substrate. The method of claim 23, wherein etching the mask patterned substrate to form a micro hole of a lattice structure in the thin film, A method of manufacturing a composite membrane having a thin thickness, characterized in that dry etching is performed using an ICP (Induced Coupled Plama) etching apparatus. The method of claim 23, wherein etching the mask patterned substrate to form a micro hole of a lattice structure in the thin film, The composite membrane manufacturing method having a thin thickness, characterized in that further forming a sub-micropore in the micro hole of the lattice structure. The method of claim 23, wherein etching the mask patterned substrate to form a micro hole of a lattice structure in the thin film, A method of manufacturing a composite membrane having a thin thickness, characterized in that wet etching is performed in an etching solution so that the inner wall surface of the micro holes of the lattice structure is not vertical but has an inclination. 24. The method of claim 23, wherein the ion exchange resin mixture comprises a surfactant. The method of claim 23, wherein the step of applying and drying the ion exchange resin mixture in the micropores of the lattice structure, A method for producing a composite membrane having a thin thickness, characterized in that the coating of the ion exchange resin mixture is carried out using a spray coating method. The method of claim 23, wherein the applying and drying of the ion exchange resin mixture is repeated. Repeating the step of applying and drying the ion exchange resin mixture so that the ion exchange resin mixture is completely filled in the micro holes of the lattice structure on one side of the thin film; Separating the thin film from the substrate; A method of manufacturing a composite membrane having a thin thickness, further comprising applying and drying an ion exchange resin mixture on the other side of the thin film. A composite membrane produced by the method of any one of claims 23-30. A composite membrane according to any one of claims 1 to 8 or 10 to 22, or a composite membrane prepared by the method according to any one of claims 23 to 30. Membrane electrode assembly. A composite membrane according to any one of claims 1 to 8 or 10 to 22, or a composite membrane prepared by the method according to any one of claims 23 to 30. Unit cell. A composite membrane according to any one of claims 1 to 8 or 10 to 22, or a composite membrane prepared by the method according to any one of claims 23 to 30. Fuel cell stack. A composite membrane according to any one of claims 1 to 8 or 10 to 22, or a composite membrane prepared by the method according to any one of claims 23 to 30. Fuel cell system. A composite membrane according to any one of claims 1 to 8 or 10 to 22, or a composite membrane prepared by the method according to any one of claims 23 to 30. sensor.