KR20140046213A - Composite electrolyte membrane for fuel cell, method for manufacturing the same and membrane eletrode assembly and fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a composite electrolyte membrane for a fuel cell which includes at least two polymer electrolyte layers and at least one porous support layer formed of a nanofiber structure and located between the polymer electrolyte layers; a method for producing the same; and a membrane electrode assembly and the fuel cell comprising the same.

Description

A composite electrolyte membrane for a fuel cell, a method of manufacturing the same, and a membrane electrode assembly and a fuel cell including the same TECHNICAL FIELD

The present application relates to a composite electrolyte membrane for a fuel cell, a manufacturing method thereof, and a membrane electrode assembly and a fuel cell including the same.

2. Description of the Related Art In recent years, due to rapid diffusion of portable electronic devices and wireless communication devices, much attention and research have been made on the development of a fuel cell as a portable power source battery, a fuel cell for a pollution-free vehicle, and a fuel cell for power generation as a clean energy source.

A fuel cell is an energy conversion device that converts chemical energy of a fuel directly into electrical energy. That is, a fuel cell uses a fuel gas and an oxidizing agent and generates electricity using electrons generated during the oxidation / reduction reaction. As a result, the fuel cell has a high energy efficiency and an environment- Research and development.

BACKGROUND OF THE INVENTION Polymer Electrolyte Membrane Fuel Cells (PEMFCs) have been spotlighted as portable, automotive, and home power supplies for their low operating temperatures, elimination of leaks due to the use of solid electrolytes, and fast operation. In addition, it is a high-output fuel cell having a higher current density than other types of fuel cells, and is operated at a temperature of less than 100 ° C, has a simple structure, has a fast start-up and response characteristics, and has excellent durability. Can be used as fuel. In addition, miniaturization can be achieved with a high output density, and research on a portable fuel cell continues.

The unit cell structure of the fuel cell has a structure in which an anode and a cathode are coated on both sides of an electrolyte membrane made of a polymer material, which is called a membrane electrode assembly (MEA). This membrane electrode assembly (MEA) is composed of a cathode, an anode, and an electrolyte membrane, that is, an ion conductive electrolyte membrane, where electrochemical reaction of hydrogen and oxygen takes place.

In general, in order to reinforce the durability of the polymer electrolyte membrane for fuel cells, attempts have been made to improve the electrolyte membrane resin itself or to fill the porous membrane with the electrolyte membrane resin. However, when the strength of the electrolyte membrane itself is increased, the ion exchange ability is generally inferior, and the method of filling the porous substrate has the effect of improving the durability, but there are many difficulties in the process, and the cost of the raw material is increased. As another method, there is a method of mixing an electrolyte membrane resin and a material for improving durability, but the mixing process is not easy and most of all, it does not show a clear effect.

Therefore, there is a need to develop an electrolyte membrane that has improved durability and no loss of ion conductivity.

Korean Patent Publication No. 10-2007-0056746

The problem to be solved by the present application is to provide a composite electrolyte membrane for fuel cells with improved durability by introducing a porous support having a thin thickness and excellent porosity.

One embodiment of the present application is at least two polymer electrolyte layers; And provided between the polymer electrolyte layer, provides a composite electrolyte membrane for a fuel cell comprising at least one porous support layer made of a nanofiber structure.

One embodiment of the present application comprises the steps of forming a first porous support layer made of a nanofiber structure in the first polymer electrolyte layer; And it provides a method for producing a composite electrolyte membrane for a fuel cell comprising the step of forming a second polymer electrolyte layer on top of the first porous support layer.

An exemplary embodiment of the present application is the composite electrolyte membrane; And it provides a fuel cell membrane electrode assembly comprising an anode and a cathode provided on both sides of the composite electrolyte membrane.

An exemplary embodiment of the present application includes at least one membrane electrode assembly including a cathode and an anode positioned opposite to each other, and an organic composite electrolyte membrane provided between the cathode and the anode; And a separator plate provided between each of the membrane electrode assemblies.

An exemplary embodiment of the present application provides a fuel cell including the composite electrolyte membrane.

Since the composite electrolyte membrane for a fuel cell according to the exemplary embodiment of the present application uses a porous support having a small thickness and a high porosity, there is an advantage in that durability of the electrolyte membrane is improved due to excellent hydrogen ion conductivity, mechanical properties, dimensional stability, and chemical resistance.

1 is a view for explaining the principle of electricity generation of the fuel cell.
2 is a view schematically showing a composite electrolyte membrane according to an exemplary embodiment of the present application.
3 is a view schematically showing a composite electrolyte membrane according to an exemplary embodiment of the present application.
4 is a schematic view of a composite electrolyte membrane according to one embodiment of the present application.
5 is a view schematically showing the structure of a membrane electrode assembly for a fuel cell according to an exemplary embodiment of the present application.
6 is a view schematically showing the structure of a membrane electrode assembly for a fuel cell according to an exemplary embodiment of the present application.
7 is a view schematically showing a structure of a fuel cell according to an exemplary embodiment of the present application.
Figure 8 shows the appearance of the surface of the porous support layer in the composite electrolyte membrane of Example 1 observed through a scanning electron microscope.
FIG. 9 shows measurement results of humidification-humidification cycle experiments of fuel cells prepared using the electrolyte membranes of Example 1 and Comparative Example 1. FIG.

Advantages and features of the present application, and a method of achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present application is not limited to the embodiments disclosed below, but will be implemented in various different forms, only the embodiments make the disclosure of the present application complete, and those skilled in the art to which the present application pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present application is defined only by the scope of the claims. The dimensions and relative sizes of the components shown in the figures may be exaggerated for clarity of description.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this application belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, the present application will be described in detail.

One embodiment of the present application is at least two polymer electrolyte layers; And provided between the polymer electrolyte layer, provides a composite electrolyte membrane for a fuel cell comprising at least one porous support layer made of a nanofiber structure.

2 schematically shows a composite electrolyte membrane according to one embodiment of the present application. In FIG. 2, reference numerals 110 and 130 are polymer electrolyte layers, and reference numeral 120 is a porous support layer.

In one embodiment of the present application, the porous support layer may be a nanofiber structure including a polymer including a hydrophilic group. Specifically, the hydrophilic group may be a hydroxyl group (—OH group) or a peptide group. The polymer including a hydrophilic group such as a hydroxyl group or a peptide group may specifically include one or two or more mixtures selected from the group consisting of cellulose, polyvinyl alcohol (PVA), chitosan, silk, spider silk, hemp, cotton and wool. And cellulose is preferable.

The hydroxyl group of the cellulose-based nanofibers is preferably present in the range of 5% to 90% relative to the total hydroxyl group site. If the amount of the hydroxy group is too small, the degree of absorption and swelling of the water is low, and thus the bonding strength with the cationic resin is low, and thus, it is not conducive to improving the mechanical strength of the fuel cell membrane. It is not preferable because the electrolyte membrane may be difficult to prepare.

More preferred content of the hydroxy group may be 10% to 80%, in particular 20% to 70%.

The cellulose-based nanofibers may be roughly classified into, for example, cellulose nanofibers having a hydroxyl group unsubstituted and cellulose nanofibers partially substituted with hydroxy such as cellulose ester nanofibers and cellulose ether nanofibers. It may be used in the form of a mixture of two or more. Specific examples thereof include cellulose nanofibers having an unsubstituted hydroxy group; Cellulose nanofibers substituted with acetyl groups or derivatives thereof; Sulfate cellulose nanofibers; Phosphate cellulose nanofibers; Cellulose nanofibers substituted with C ₁ -C ₁₀ alkyl groups or derivatives thereof, such as methyl cellulose nanofibers, ethyl cellulose nanofibers, carboxymethyl cellulose nanofibers, hydroxyethyl cellulose nanofibers, and the like, and more specifically, C It may be one or more selected from the group consisting of; cellulose nanofiber substituted with a ₂ -C ₆ alkyl group or a derivative thereof, but is not limited thereto. Among them, more specifically, a cellulose nanofiber substituted with a low water-soluble C ₂ -C ₁₀ alkyl group or a derivative thereof, or a cellulose nanofiber substituted with an acetyl group or a derivative thereof can be used.

The porous support including the nanofibers having the hydrophilic group can reduce stress due to volume change by interlocking with the swelling and shrinkage of the hydrocarbon-based cation exchange resin, and shrinkage due to moisture loss even at low humidification conditions due to the presence of the hydrophilic group. The degree can be reduced and the tensile strength can be improved when exposed to moisture.

Since the fiber having a hydrophilic group includes a hydrophilic group such as a hydroxy group (-OH) or a peptide group, it has excellent miscibility with a cation exchange resin and thus is polytetrafluoroethylene (PTFE: Polytetrafluoroethylene) or polyvinylidene fluoride (PVDF). : Compared with other porous substrates such as polyvinylidenefluoride (PI) or polyimide (PI), polymer cation exchange resin is easier to input.

In one embodiment of the present application, the diameter of the nanofibers included in the porous support may be 1 nanometer to 1 micrometer. If the diameter of the fibrous nanofibers is less than 1 nanometer, the diameter may be too small to contribute to the improvement of the mechanical strength. If the diameter of the fibrous nanofibers is more than 1 micrometer, the diameter is too large and the distance between the cation exchange resins becomes far. The range of 1 nanometer to 1 micrometer is preferred, as this may interfere with hydrogen ion transfer.

The nanofiber structure of the porous support may be formed through electrospinning. By adjusting the method and process conditions of electrospinning, it is possible to form a support structure comprising nanofibers including pores.

In one embodiment of the present application, the average diameter of the pores formed in the porous support may be a few nanometers to several micrometers, for example 1 nanometer to 10 micrometers. If the average diameter of the pores is less than 1 nanometer, it may be difficult to penetrate the polymer cation exchange resin, and if the average pore diameter exceeds 10 micrometers, the uniformity of the pores may be reduced and the desired mechanical strength may be difficult to obtain. The range of meters is preferred.

In one embodiment of the present application, the thickness of the porous support layer may be 1 micrometer to 50 micrometers, specifically 1 micrometer to 20 micrometers, more specifically 1 micrometer to 10 micrometers Can be. If it is less than 1 micrometer, it is difficult to aim at the improvement of mechanical property to a desired level, and if it is more than 50 micrometer, since resistance becomes large, the range of 1 micrometer-50 micrometers is preferable. The effect is even better when the thickness is between 1 micrometer and 20 micrometers, more specifically between 1 micrometer and 10 micrometers.

In one embodiment of the present application, the porosity of the porous support may be from 50% to 95% by volume of the total volume, and more specifically from 70% to 95% by volume of the total volume. If it is less than 50% by volume, the hydrogen ion conductivity may be lowered. If it is more than 95%, the effect of increasing the mechanical strength is insignificant, which is not preferable.

In an exemplary embodiment of the present application, as long as the polymer used in the polymer electrolyte layer has hydrogen ion conductivity, conventional ones known in the art may be used. The polymer having hydrogen ion conductivity may be a polymer having one or two or more cation exchange groups selected from the group consisting of sulfonic acid groups, phosphoric acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, and derivatives thereof in the side chain. Specifically, benzimidazole-based polymer, polyimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, polysulfone-based polymer, polyether sulfone-based polymer, polyether ketone-based polymer, polyether-etherketone-based It may include one or two or more mixtures selected from the group consisting of a polymer and a polyphenylquinoxaline-based polymer.

In one embodiment of the present application, the thickness of the composite electrolyte membrane for a fuel cell may be 5 micrometers to 100 micrometers, specifically 5 micrometers to 50 micrometers, and more specifically 10 micrometers to 20 micrometers It can be meters. If the thickness of the composite electrolyte membrane is less than 5 micrometers, it may be difficult to have a desired level of mechanical strength, and if it exceeds 100 micrometers, the hydrogen ion conductivity may be lowered, and it is preferable that it is 5 micrometers to 100 micrometers.

In an exemplary embodiment of the present application, the composite electrolyte membrane has the same thickness of the polymer electrolyte layers so that the porous support layer may be provided at the center of the composite electrolyte membrane.

2 illustrates an example in which the porous support layers are provided at the center of the composite electrolyte membrane because the thicknesses of the polymer electrolyte layers are the same. In FIG. 2, the distance d1 from the center of the porous support to one end of the composite electrolyte membrane is the same as the distance d2 from the center of the porous support to the other end of the composite electrolyte membrane.

In an exemplary embodiment of the present application, the composite electrolyte membrane may have a different thickness of the polymer electrolyte layer, and the porous support layer may be disposed toward the polymer electrolyte layer in contact with the cathode or the anode. Specifically, the porous support layer may be provided by biasing the polymer electrolyte layer in contact with the cathode. In the cathode, since water is generated by the electrochemical reaction, a relatively large amount of water may be present in comparison with the anode, and thus may be greatly affected by water. When the porous support is biased toward the cathode, durability improvement effect may be increased.

Figure 3 schematically shows a composite electrolyte membrane according to one embodiment of the present application. In FIG. 3, reference numerals 110 and 130 are polymer electrolyte layers, and reference numeral 120 is a porous support layer. 3 shows an example in which the thickness of the polymer electrolyte layer is different so that the porous support layer is biased toward one of the polymer electrolyte layers. In FIG. 3, the distance d1 from the center of the porous support to one end of the composite electrolyte membrane is smaller than the distance d2 from the center of the porous support to the other end of the composite electrolyte membrane.

For example, when the distance from one end of the composite electrolyte membrane to the other end is 100%, the distance from the center of the porous support to one end of the composite electrolyte membrane may be 5% or more and less than 50%, more specifically 10% or more. Or 40% or less.

In one embodiment of the present application, the polymer electrolyte layer may be two, and the porous support layer may be one. In this case, the first polymer electrolyte layer; A porous support layer; And it may be provided in the order of the second polymer electrolyte layer. 2 and 3 show an example provided in the order of the polymer electrolyte layer / porous support layer / polymer electrolyte layer.

In one embodiment of the present application, the polymer electrolyte layer may be three, and the porous support layer may be two. In this case, the first polymer electrolyte layer; A first porous support layer; A second polymer electrolyte layer; A second porous support layer; And it may be provided in the order of the third polymer electrolyte layer.

4 schematically shows a composite electrolyte membrane according to one embodiment of the present application. In FIG. 4, reference numerals 110, 130, and 150 are polymer electrolyte layers, and reference numerals 120 and 140 are porous support layers, and a polymer electrolyte layer / porous support layer / polymer electrolyte layer / porosity. An example provided in the order of the support layer / polymer electrolyte layer is shown.

In the exemplary embodiment of the present application, the polymer electrolyte layer may be four, and the porous support layer may be three. In this case, the first polymer electrolyte layer; A first porous support layer; A second polymer electrolyte layer; A second porous support layer; And a third polymer electrolyte layer; A third porous support layer; And a fourth polymer electrolyte layer. In this case, it may be provided in the order of the polymer electrolyte layer / porous support layer / polymer electrolyte layer / porous support layer / polymer electrolyte layer / porous support layer / polymer electrolyte layer.

One embodiment of the present application comprises the steps of forming a first porous support layer made of a nanofiber structure in the first polymer electrolyte layer; And it provides a method for producing a composite electrolyte membrane for a fuel cell comprising the step of forming a second polymer electrolyte layer on top of the first porous support layer.

The manufacturing method includes forming a second porous support layer on top of the second polymer electrolyte layer; And forming a third polymer electrolyte layer on the second porous support layer.

The manufacturing method includes forming a second porous support layer on top of the second polymer electrolyte layer; Forming a third polymer electrolyte layer on top of the second porous support layer; Forming a third porous support layer on top of the third polymer electrolyte layer; And forming a fourth polymer electrolyte layer on the third porous support layer.

In an exemplary embodiment of the present application, the formation of the polymer electrolyte layer is not particularly limited, but for example, a method of applying a polymer electrolyte solution may be used.

In one embodiment of the present application, the porous support layer may be formed using an electrospinning method.

Description of the porous support layer, the polymer electrolyte layer and the composite electrolyte membrane in the above production method is as described above.

By adjusting the method and process conditions of the electrospinning, it is possible to control the diameter of the nanofibers and the arrangement direction of the fibers. In this case, the fibers may be randomly arranged and may be formed by arranging the fibers in one direction. The electrospinning may be performed by applying a high voltage of about 1 kV to about 1,000 kV. Electrospinning can be carried out according to a general method.

One embodiment of the present application is a composite electrolyte membrane; And it provides a fuel cell membrane electrode assembly comprising an anode and a cathode provided on both sides of the composite electrolyte membrane.

In one embodiment of the present application, the anode and the cathode may include a catalyst layer. The anode and the cathode may further include a gas diffusion layer.

The membrane electrode assembly for a fuel cell is advantageous in that the mechanical strength of the polymer electrolyte membrane inside the fuel cell during operation is greatly improved, and the durability is excellent. In addition, hydrogen ion conductivity is also excellent.

The electrode may be prepared according to conventional methods known in the art, for example, a catalyst including a metal catalyst, a hydrogen ion conductive polymer, a metal catalyst supported on a carbon-based support, a polymer ionomer, and a solvent to enhance catalyst dispersion. The catalyst layer can be formed by applying and drying the ink on the gas diffusion layer, and the electrode can be produced by the above method.

As the metal catalyst, any one or a mixture of two or more selected from the group consisting of platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and platinum-transition metal alloy may be used. It is not limited to this.

The carbonaceous support may include graphite (graphite), carbon black, acetylene black, denka black, canyon black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanohorns, and carbon nanorings. One or a mixture of two or more selected from the group consisting of carbon nanowires, fullerenes (C60), and super P may be preferable.

As the polymer ionomer, sulfonated polymers such as nafion ionomer or sulfonated polytrifluorostyrene may be representatively used.

As the solvent, any one or a mixture of two or more selected from the group consisting of water, butanol, iso propanol, methanol, ethanol, n-propanol, n-butyl acetate and ethylene glycol may be preferably used.

In this case, the method of coating the catalyst ink on the gas diffusion layer may include, but is not limited to, printing, spraying, rolling, or brushing.

The gas diffusion layer is not particularly limited as long as the substrate is generally conductive and has a porosity of 80% or more, and may include a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt. The gas diffusion layer may further include a microporous layer formed on one surface of the conductive base material, and the microporous layer may include a carbon-based material and a fluororesin.

Examples of the carbon-based material include graphite (graphite), carbon black, acetylene black, denka black, canyon black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon nanorings, carbon nanowires, One or a mixture of two or more selected from the group consisting of fullerene (C60) and super P may be used, but is not limited thereto.

Examples of the fluororesin include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose acetate, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP) or styrene-butadiene rubber. One or a mixture of two or more selected from the group consisting of (SBR) may be used, but is not limited thereto.

Non-limiting examples of solvents used to enhance the catalyst dispersion in electrode preparation include water, butanol, isopropyl alcohol (IPA), methanol, ethanol, n-propanol, n-butyl acetate, ethylene glycol, and the like. In addition, these solvent can be used individually or in mixture of 2 or more types.

The membrane electrode assembly may be formed in a manner such that the catalyst layer of the anode and the catalyst layer of the cathode are in contact with the electrolyte membrane, according to a conventional method known in the art. In one example, the cathode; Anode; And it may be prepared by thermocompression bonding at 100 to 400 ℃ in a state in which the electrolyte membrane located between the cathode and the anode in close contact

5 shows a structure of a membrane electrode assembly for a fuel cell according to an embodiment of the present application.

Referring to FIG. 5, the membrane electrode assembly for a fuel cell according to the present application may include a cathode electrode 203 and an anode electrode 205 positioned to face each other with the composite electrolyte membrane 100 interposed therebetween. . The cathode and the anode may further include a gas diffusion layer 208, and the gas diffusion layer 208 may include substrates 209a and 209b and microporous layers 207a and 207b formed on one surface of the substrate.

In one embodiment of the present application, the porous support inside the composite electrolyte membrane may have the same distance from the anode and the cathode. Specifically, the composite electrolyte membrane may have the same distance from the center of the porous support to one end of the composite electrolyte membrane. That is, the distance from the center of the porous support to one end of the composite electrolyte membrane in the anode direction is the same as the distance from the center of the porous support to one end of the composite electrolyte membrane in the cathode direction. Therefore, the distance from the anode to the center of the porous support and the distance from the cathode to the center of the porous support can be the same so that the composite electrolyte membrane can be located at the central portion of the membrane electrode assembly.

In FIG. 5, the distance d1 from the center of the porous support to one end of the composite electrolyte membrane in the cathode direction is the same as the distance d2 from the center of the porous support to one end of the composite electrolyte membrane in the anode direction.

In one embodiment of the present application, the composite electrolyte membrane may be present biased toward the cathode in the membrane electrode assembly. Specifically, when the composite electrolyte membrane is 100% of the distance from one end of the composite electrolyte membrane to the other end, the distance from the center of the porous support to one end in the cathode direction of the composite electrolyte membrane may be greater than or equal to 5% and less than 50%. Specifically, 10% or more and 40% or less.

In one embodiment of the present application, the composite electrolyte membrane may be present biased toward the anode in the membrane electrode assembly. Specifically, in the composite electrolyte membrane, when the distance from one end of the composite electrolyte membrane to the other end is 100%, the distance from the center of the porous support to one end in the anode direction of the composite electrolyte membrane may be 5% or more and less than 50%. Specifically, 10% or more and 40% or less.

6 illustrates a structure of a membrane electrode assembly for a fuel cell according to an exemplary embodiment of the present application, in which a composite electrolyte membrane is biased toward a cathode in the membrane electrode assembly.

Referring to FIG. 6, the membrane electrode assembly for a fuel cell according to the present application has a distance D from one end of the composite electrolyte membrane to the other end at 100%, from the center of the porous support to the end of the cathode of the composite electrolyte membrane. It shows a structure in which the distance d1 is 30%.

An exemplary embodiment of the present application includes at least one membrane electrode assembly including a cathode and an anode positioned opposite to each other, and the composite electrolyte membrane provided between the cathode and the anode; And a separator plate provided between each of the membrane electrode assemblies.

The separator plate prevents the membrane electrode assemblies from being electrically connected to each other, and contacts the cathode and the anode of the membrane electrode assembly to transfer the fuel and the oxidant supplied from the outside to the membrane electrode assembly. A channel channel may be formed inside the separator plate.

The stack for a fuel cell serves to generate electricity through an electrochemical reaction between a fuel and an oxidant.

An exemplary embodiment of the present application provides a fuel cell including the composite electrolyte membrane.

In an exemplary embodiment of the present application, the fuel cell includes a fuel cell stack including a separator provided between at least one membrane electrode assembly and the membrane electrode assembly; A fuel supply unit supplying fuel to the stack; And an oxidant supply unit supplying an oxidant to the stack.

7 schematically illustrates a structure of a fuel cell according to an exemplary embodiment of the present application.

Referring to FIG. 7, the fuel cell of the present application includes a fuel cell stack 200, a fuel supply unit 400, and an oxidant supply unit 300. The fuel cell of the present application includes at least one membrane electrode assembly and at least one separator plate including a cathode and an anode positioned opposite to each other, and between the anode and the cathode, the composite electrolyte membrane for a fuel cell according to the present application, At least one fuel cell stack 200 for generating electricity through an electrochemical reaction of a fuel and an oxidant; A fuel supply unit 400 for supplying fuel to the electricity generating unit; And an oxidant supply unit 300 for supplying the oxidant to the electricity generating unit.

The fuel supply unit 400 supplies fuel to the electricity generating unit and includes a fuel tank 410 for storing the fuel and a pump 420 for supplying the fuel stored in the fuel tank 410 to the electricity generating unit 200 ). The fuel may be selected from the group consisting of methanol, ethanol, butanol, propanol, formic acid, aqueous hydrogen compound solution and hydrogen gas. More specifically, it may be a hydrogen gas.

The oxidant supply unit 300 serves to supply an oxidant to the electricity generator. The oxidant may be oxygen or air and may be used by injecting oxygen or air into the pump 300.

Hereinafter, the contents of the present application will be described in detail through Examples, Comparative Examples, and Experimental Examples, but the scope of the present application is not limited thereto.

 Example 1

5 parts by weight of sulfonated polyether-etherketone were dissolved in 95 parts by weight of DMSO as a solvent. This was applied to the substrate by a solution casting method using a film applicator. Then, the temperature was gradually increased to 80 ° C., followed by drying for about 24 hours, and further drying at 120 ° C. for 24 hours to prepare a first polymer electrolyte layer having a thickness of 5 micrometers.

To prepare a solution for electrospinning, 7.5 parts by weight of ethyl cellulose powder (Dow, ETHOCEKTM, substituted 48-49.5% ethyl group) was dissolved in 92.5 parts by weight of DMAc, followed by an electrospinning machine (Electrospinning / Electrospray Machine, NanoNC Co. Ltd.) Was spun onto the first polymer electrolyte layer prepared above. Then, dried at 50 ° C. for 4 hours. The nozzle used for electrospinning had an inner diameter of 0.51 mm and an outer diameter of 0.81 mm, a spinning flow rate of 100 μL / min, and a spinning voltage of 20 kV. The porous support layer was formed on the first polymer electrolyte layer through electrospinning, and the surface of the porous support layer was observed through a scanning electron microscope in FIG. 8. At this time, the diameter of the formed ethyl cellulose nanofibers was in the range of 100nm to 300nm.

The sulfonated polyether-etherketone solution was cast on the porous support layer prepared above to form a second polymer electrolyte layer. The formation method is the same as that of forming the first polymer electrolyte layer. After proton exchange by sulfuric acid treatment to finally prepare a composite electrolyte membrane.

[Comparative Example 1]

5 parts by weight of sulfonated polyether-etherketone were dissolved in 95 parts by weight of DMSO as a solvent. This was applied to the substrate by a solution casting method using a film applicator. Then, the mixture was gradually heated up to 80 ° C., dried for about 24 hours, and dried at 120 ° C. for 24 hours to prepare a pure electrolyte membrane composed of a polymer electrolyte layer having a thickness of 16 micrometers.

[Experimental Example 1]

The water content and the dimensional stability of the composite electrolyte membrane and the pure electrolyte membrane prepared in Example 1 and Comparative Example 1 were measured. First, each electrolyte membrane was impregnated in distilled water at room temperature for 24 hours, and then its weight and dimensions were measured. Then, the weight and dimensions of each electrolyte membrane after drying in a vacuum oven at 100 ° C. for 24 hours were measured and the results are shown in Table 1 below.

Moisture content
(weight%) Dimensional change △ L (length direction) △ T (thickness direction) ΔV (volume) Comparative Example 1 30 12.5 17.6 48.8 Example 1 13.9 3.5 6.7 14.3

Referring to Table 1, it can be seen that the composite electrolyte membrane prepared in Example 1 has a lower moisture content and relatively less dimensional change than the pure electrolyte membrane prepared in Comparative Example 1. This seems to be because the porous support introduced into the composite electrolyte membrane somewhat relieved the membrane from being swollen by water. It was also speculated that this would have a positive effect on the humidification-no-humidity cycle assessment, where swelling and shrinking were repeated.

 [Production Example 1]

A membrane electrode assembly and a fuel cell were manufactured using the composite electrolyte membrane prepared in Example 1 above. To this end, a platinum-carrying carbon catalyst and a Nafion ionomer were dissolved in a mixed solvent of water and isopropyl alcohol, and then coated on carbon paper to prepare two gas diffusion layers in which 0.4 mg / cm ² of platinum was present. After the electrolyte membrane was placed between two gas diffusion layers, an electrode membrane assembly was prepared by thermocompression bonding at 140 ° C. for 5 minutes. The membrane electrode assembly thus prepared was applied to a unit cell device having a structure as shown in FIG. 7 to manufacture a fuel cell.

[Comparative Production Example 2]

A membrane electrode assembly and a fuel cell were manufactured in the same manner as in Preparation Example 1 using the pure electrolyte membrane prepared in Comparative Example 1.

[Experimental Example 2]

RH durability evaluation of the composite electrolyte membrane and the pure electrolyte membrane prepared in Example 1 and Comparative Example 1 was carried out using the fuel cell of Preparation Example 1 and Comparative Preparation Example 1. Humidification-humidification cycle experiment was performed by supplying nitrogen gas of RH 150% and RH 0% at two minute intervals to both gas inlets of the fuel cell at 80 ° C. The hydrogen (H ₂ ) crossover was periodically measured during the experiment and the experiment was stopped when the hydrogen crossover increased sharply. The experimental results are shown graphically in FIG. 9.

Referring to FIG. 9, it can be seen that in the fuel cell manufactured using the pure electrolyte membrane prepared in Comparative Example 1, the hydrogen (H ₂ ) crossover increases rapidly from the beginning of the humidification-no humidification cycle. This is because hydrogen (H ₂ ) channels are formed due to micropores and cracks in the polymer electrolyte membrane due to repeated swelling and contraction. On the contrary, in the fuel cell manufactured using the composite electrolyte membrane prepared in Example 1, it can be seen that the hydrogen crossover is maintained in a similar range to the initial stage even though the hydrogen crossover does not rapidly rise up to 2,000 cycles. This result is understood as the porous support used in Example 1 as described above greatly improves the RH durability of the polymer electrolyte membrane.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Having described specific portions of the present application in detail, those skilled in the art will appreciate that these specific embodiments are merely preferred embodiments and that the scope of the present application is not limited thereto. Accordingly, the actual scope of the present application will be defined by the appended claims and their equivalents.

100: composite electrolyte membrane
110, 130, 150: polymer electrolyte layer
120, 140: porous support layer
130: polymer electrolyte layer
203: cathode electrode
205: anode electrode
207a and 207b: microporous layer
208: gas diffusion layer
209a and 209b: substrate
d1: distance from the center of the porous support to one end of the composite electrolyte membrane
d2: distance from the center of the porous support to one end of the composite electrolyte membrane
D: Distance from one end of the composite electrolyte membrane to the other
200: stack for fuel cells
300: oxidant supply unit
400: fuel supply unit
410: fuel tank
420: pump

Claims (28)

At least two polymer electrolyte layers; And
A composite electrolyte membrane for a fuel cell, which is provided between the polymer electrolyte layers and comprises at least one porous support layer made of a nanofiber structure. The method according to claim 1,
The porous support layer is a composite electrolyte membrane for a fuel cell, characterized in that it comprises a hydrophilic group. The method according to claim 1,
The porous support layer is a composite electrolyte membrane for a fuel cell, characterized in that it comprises a hydroxyl group or a peptide group. The method according to claim 1,
The porous support layer is cellulose, polyvinyl alcohol (PVA), chitosan, silk, spider silk, hemp, cotton and wool, the composite electrolyte membrane for a fuel cell, characterized in that it comprises one or more selected from the group consisting of. The method according to claim 1,
The porosity of the porous support is a composite electrolyte membrane for a fuel cell, characterized in that 50% to 95% by volume of the total volume. The method according to claim 1,
The nanofiber diameter of the porous support is 1 nanometer to 1 micrometer composite electrolyte membrane for a fuel cell, characterized in that. The method according to claim 1,
The thickness of the porous support layer is a composite electrolyte membrane for a fuel cell, characterized in that 1 micrometer to 50 micrometers. The method according to claim 1,
The thickness of the porous support layer is a composite electrolyte membrane for a fuel cell, characterized in that 1 micrometer to 10 micrometers. The method according to claim 1,
The polymer electrolyte layer is a composite electrolyte membrane for a fuel cell, characterized in that it comprises a polymer having a hydrogen ion conductivity. The method according to claim 1,
The polymer electrolyte layer includes a polymer having one or more cation exchange groups selected from the group consisting of sulfonic acid groups, phosphoric acid groups, carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, and derivatives thereof in the side chain thereof. Electrolyte membrane. The method according to claim 1,
The polymer electrolyte layer may be benzimidazole-based polymer, polyimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, polysulfone-based polymer, polyethersulfone-based polymer, polyetherketone-based polymer, polyether-ether A composite electrolyte membrane for a fuel cell, comprising one or two or more mixtures selected from the group consisting of ketone-based polymers and polyphenylquinoxaline-based polymers. The method according to claim 1,
The thickness of the composite electrolyte membrane is a composite electrolyte membrane for a fuel cell, characterized in that less than 100 micrometers. The method according to claim 1,
The thickness of the composite electrolyte membrane is a composite electrolyte membrane for a fuel cell, characterized in that 10 to 20 micrometers. The method according to claim 1,
The composite electrolyte membrane
A composite electrolyte membrane for a fuel cell, characterized in that two polymer electrolyte layers and one porous support layer. The method according to claim 1,
The composite electrolyte membrane
A composite electrolyte membrane for a fuel cell, characterized in that three polymer electrolyte layers and two porous support layers. The method according to claim 1,
The composite electrolyte membrane has a same thickness of the polymer electrolyte layer, so that the porous support layer is provided in the center of the composite electrolyte membrane composite electrolyte membrane for a fuel cell. The method according to claim 1,
The composite electrolyte membrane has a different thickness of the polymer electrolyte layer, the porous support membrane is a composite electrolyte membrane for a fuel cell, characterized in that provided with a bias toward any one of the polymer electrolyte layer. 18. The method of claim 17,
The composite electrolyte membrane is a composite electrolyte membrane for a fuel cell, characterized in that the porous support layer is provided with a polymer electrolyte layer in contact with the cathode. Forming a first porous support layer having a nanofiber structure on the first polymer electrolyte layer; And
Method of manufacturing a composite electrolyte membrane for a fuel cell comprising the step of forming a second polymer electrolyte layer on top of the first porous support layer. The method of claim 19,
Forming a second porous support layer on top of the second polymer electrolyte layer; And
The method of manufacturing a composite electrolyte membrane for a fuel cell further comprising the step of forming a third polymer electrolyte layer on top of the second porous support layer. The method of claim 19,
The composite electrolyte membrane is a method of manufacturing a composite electrolyte membrane for a fuel cell, characterized in that the same thickness of the polymer electrolyte layer is formed with a porous support layer in the center of the composite electrolyte membrane. The method of claim 19,
The composite electrolyte membrane is a method for producing a composite electrolyte membrane for a fuel cell, characterized in that the polymer electrolyte layers are formed differently so that the porous support layer is biased toward any one of the polymer electrolyte layer. The method of claim 19 or 20,
Forming the porous support layer is a method for producing a composite electrolyte membrane for a fuel cell, characterized in that using the electrospinning method. The composite electrolyte membrane of any one of claims 1 to 18; And
Membrane electrode assembly for a fuel cell comprising an anode and a cathode provided on both sides of the composite electrolyte membrane. 27. The method of claim 24,
The anode and the cathode further comprises a gas diffusion layer fuel cell membrane electrode assembly. At least one membrane electrode assembly comprising a cathode and an anode positioned opposite to each other, and the composite electrolyte membrane of any one of claims 1 to 18 provided between the cathode and the anode; And
And a separator plate provided between each of the membrane electrode assemblies. A fuel cell comprising the composite electrolyte membrane of claim 1. The fuel cell of claim 27, wherein the fuel cell
A stack for a fuel cell including a separator plate provided between at least one membrane electrode assembly and a membrane electrode assembly;
A fuel supply unit supplying fuel to the stack; And
A fuel cell comprising an oxidant supply unit for supplying an oxidant to the stack.

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