Reinforced composite membrane for fuel cell, manufacturing method thereof, and membrane-electrode assembly for fuel cell comprising the same

Abstract

The present invention relates to a reinforced composite membrane for a fuel cell comprising a porous support and a hydrogen ion-conducting polymer, wherein the reinforced composite membrane comprises an electrolyte layer comprising the hydrogen ion-conducting polymer on at least one surface of the porous support, and wherein the porous support further comprises a compound capable of capturing metal ions. The invention also relates to a method for manufacturing the same and a membrane-electrode assembly comprising the same.

Description

Technology Field

[0001] The present invention relates to a reinforced composite membrane for a fuel cell, a method for manufacturing the same, and a membrane-electrode assembly for a fuel cell comprising the same. Background Technology

[0002] Due to the recent rapid proliferation of portable electronic and wireless communication devices, significant interest and research are being conducted on the development of fuel cells as portable power sources, fuel cells for zero-emission vehicles, and fuel cells for power generation as clean energy sources.

[0003] Polymer Electrolyte Membrane Fuel Cells (PEMFCs), which use hydrogen as fuel, are gaining popularity as power sources for vehicles and homes due to their advantages, such as the ability to operate over a wide temperature range, which simplifies cooling systems and sealing components; the use of low-humidity hydrogen as fuel, which minimizes the need for humidifiers; and rapid operation. Furthermore, as high-output fuel cells with high current density compared to other types of fuel cells, they operate over a wide temperature range, feature a simple structure, and offer fast start-up and response characteristics.

[0004] Recently, significant efforts have been underway to improve the long-term performance of electrolyte membranes, a core component of fuel cells. High ion conductivity at low humidity is a critical factor for achieving both price competitiveness and performance enhancement.

[0005] Among various types of electrolyte membranes, perfluorinated electrolyte membranes have excellent mechanical strength and electrochemical properties, but the cost of the membrane is very high due to the complex manufacturing process, and the low glass transition temperature due to the fluorinated structure acts as a disadvantage.

[0006] As an alternative to these perfluorinated electrolyte membranes, the development of hydrocarbon polymers has been actively pursued, but in the case of hydrocarbon polymer electrolyte membranes, securing appropriate mechanical strength at the level of perfluorinated electrolyte membranes is an important challenge.

[0007] Furthermore, it has been pointed out as a significant problem that hydrocarbon polymer electrolyte membranes can experience accelerated oxidation due to hydrogen peroxide or hydroxyl radicals generated during the operation of polymer electrolyte fuel cells, and that the use of single membranes leads to a substantial decrease in mechanical durability, which in turn can significantly reduce the chemical and mechanical stability of the polymer electrolyte membrane. To achieve high performance, long-term stability, high durability, and low cost, high ionic conductivity, physicochemical stability, high mechanical strength, and high water content stability are required for the electrolyte membrane. The introduction of reinforced composite membranes can serve as an alternative to satisfy these requirements.

[0008] On the other hand, during the commercialization process of reinforced composite membranes, there were diverse demands from the industrial sector for technologies to improve various performance aspects, in addition to high durability. Examples include technologies to control the gas permeability of reinforced composite membranes, technologies to enhance the stability between the electrolyte and the support, or technologies to facilitate electrolyte impregnation; thus, there was a need for research on methods to improve the performance of reinforced composite membranes in these regards. The problem to be solved

[0009] The objective of the present invention is to provide a reinforced composite membrane for a fuel cell that can maintain the performance of the fuel cell for a long period and improve its lifespan by applying a specific compound capable of preventing the leaching of metal ions, such as radical scavengers, to the porous support of the reinforced composite membrane comprising a porous support and a hydrogen ion-conducting polymer.

[0010] Another objective of the present invention is to provide a method for manufacturing the reinforced composite membrane.

[0011] Another objective of the present invention is to provide a membrane-electrode assembly comprising the reinforced composite membrane.

[0012] Another objective of the present invention is to provide a fuel cell comprising the membrane-electrode assembly. means of solving the problem

[0013] One embodiment of the present invention provides a reinforced composite membrane for a fuel cell comprising a porous support and a hydrogen ion-conducting polymer, wherein the reinforced composite membrane comprises an electrolyte layer comprising the hydrogen ion-conducting polymer on at least one surface of the porous support, and the porous support further comprises a compound capable of capturing metal ions.

[0014] The compound capable of capturing the above metal ions may include polyethylene glycol, polypropylene glycol, polybutylene glycol, crown ether, or a combination thereof.

[0015] The weight-average molecular weight of the above polyethylene glycol, polypropylene glycol, and polybutylene glycol may be 60 to 6,000 g / mol.

[0016] The crown ether may include 12-crown-4-ether, 15-crown-5-ether, 18-crown-6-ether, benzo-15-crown-5-ether, N-phenylazo-15-crown-5-ether, 2-aminomethyl-18-crown-6, or a combination thereof.

[0017] The compound capable of capturing the metal ions may be included in an amount of 1 to 50 weight percent relative to the total weight of the porous support.

[0018] The metal ions may include cerium (Ce) ions, manganese (Mn) ions, tungsten (W) ions, cobalt (Co) ions, vanadium (V) ions, nickel (Ni) ions, chromium (Cr) ions, zirconium (Zr) ions, yttrium (Y) ions, iridium (Ir) ions, iron (Fe) ions, titanium (Ti) ions, molybdenum (Mo) ions, lanthanum (La) ions, neodymium (Nd) ions, or combinations thereof.

[0019] The thickness of the porous support above may be 1 to 100 μm.

[0020] Another embodiment of the present invention provides a method for manufacturing a reinforced composite membrane for a fuel cell, comprising the steps of: manufacturing a porous support using a composition comprising a precursor of a polymer for forming a porous support and a compound capable of capturing metal ions; and impregnating the porous support with a hydrogen ion-conducting polymer or forming an electrolyte layer comprising a hydrogen ion-conducting polymer on at least one surface of the porous support.

[0021] The polymer for forming the porous support above may be a hydrocarbon-based polymer that is insoluble in organic solvents.

[0022] The compound capable of capturing the above metal ions may include polyethylene glycol, polypropylene glycol, polybutylene glycol, crown ether, or a combination thereof.

[0023] The compound capable of capturing the above metal ions may be included in an amount of 1 to 50 parts by weight per 100 parts by weight of the composition.

[0024] The step of manufacturing the porous support above can be performed by electrospinning the composition. According to one embodiment, the electrospinning can be performed by applying an electric field of 850 V / cm to 3,500 V / cm.

[0025] The step of forming an electrolyte layer comprising the above hydrogen ion-conducting polymer may include the step of preparing a mixed solution by dispersing the above hydrogen ion-conducting polymer in a solvent, the step of forming an electrolyte layer by casting and drying the above mixed solution, and the step of laminating the electrolyte layer with the above porous support.

[0026] Another embodiment of the present invention provides a membrane-electrode assembly comprising an anode electrode and a cathode electrode positioned opposite each other, and a reinforced composite membrane for a fuel cell positioned between the anode electrode and the cathode electrode.

[0027] Another embodiment of the present invention provides a fuel cell comprising the membrane-electrode assembly. Effects of the invention

[0028] According to the present invention, by introducing a specific compound capable of capturing metal ions, such as radical scavengers, into the inside or outside of a porous support of a reinforced composite membrane, the mobility of the metal ions can be reduced to suppress their leaching, and furthermore, the aggregation of the radical scavengers themselves can be prevented to improve dispersibility.

[0029] Therefore, the performance of the fuel cell can be maintained for a long period without chemical degradation of the electrolyte membrane and / or electrode caused by radicals, specifically hydroxyl radicals, generated during the operation of the fuel cell, and its durability can be significantly improved. Brief explanation of the drawing

[0030] FIG. 1 is a schematic diagram showing a reinforced composite membrane for a fuel cell according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a membrane-electrode assembly according to one embodiment of the present invention. FIG. 3 is a schematic diagram illustrating the overall configuration of a fuel cell according to one embodiment of the present invention. Specific details for implementing the invention

[0031] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0032] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.

[0033] The term "nano" as used in this specification means nanoscale and includes a size of 1 μm or less.

[0035] Hereinafter, a reinforced composite membrane for a fuel cell according to one embodiment will be described.

[0036] The present invention relates to a reinforced composite membrane for a fuel cell that can maintain the performance of the fuel cell for a long period and improve its lifespan by applying a specific compound capable of preventing the leaching of metal ions, such as radical scavengers, to the porous support of the reinforced composite membrane comprising a porous support and a hydrogen ion-conducting polymer.

[0037] FIG. 1 is a schematic diagram showing the schematic configuration of a reinforced composite membrane for a fuel cell according to one embodiment.

[0038] Referring to FIG. 1, a reinforced composite membrane (10) for a fuel cell according to one embodiment is a reinforced composite membrane comprising a porous support (5) and a hydrogen ion conductive polymer, wherein the reinforced composite membrane comprises an electrolyte layer (1 and / or 3) comprising the hydrogen ion conductive polymer on at least one surface of the porous support (5), and the porous support may further comprise a compound capable of capturing metal ions.

[0039] Fuel cells can be classified into alkaline electrolyte fuel cells, polymer electrolyte membrane fuel cells (PEMFC), etc., depending on the state and type of electrolyte. Among these, polymer electrolyte membrane fuel cells are gaining popularity as portable, automotive, and home power supply devices due to their advantages, such as a low operating temperature of less than 100°C, fast start-up and response characteristics, and excellent durability.

[0040] Representative examples of polymer electrolyte fuel cells include proton exchange membrane fuel cells (PEMFCs) that use hydrogen gas as fuel and direct methanol fuel cells (DMFCs) that use liquid methanol as fuel.

[0041] To summarize the reactions occurring in the polymer electrolyte fuel cell described above, first, when a fuel such as hydrogen gas is supplied to the anode, hydrogen ions (H₂) are produced at the anode through the oxidation reaction of hydrogen. + ) and electrons (e - ) is generated. The generated hydrogen ions are transferred to the reduction electrode through an ion exchange membrane, and the generated electrons are transferred to the reduction electrode through an external circuit. At the reduction electrode, oxygen is supplied, and oxygen combines with hydrogen ions and electrons to produce water through the reduction reaction of oxygen.

[0042] Meanwhile, there are still many technical barriers to overcome to realize the commercialization of polymer electrolyte fuel cells, and essential improvements include achieving high performance, long lifespan, and low cost. The membrane-electrode assembly is the component that has the greatest impact on this, and among them, the ion exchange membrane is one of the key factors that most significantly affects the performance and price of the MEA.

[0043] The requirements for ion exchange membranes necessary for the operation of the aforementioned polymer electrolyte fuel cell include high hydrogen ion conductivity, chemical stability, low fuel permeability, high mechanical strength, low water content, and excellent dimensional stability. Conventional ion exchange membranes tend to struggle to exhibit normal high performance in specific temperature and relative humidity environments, particularly under high temperature and low humidity conditions. Consequently, polymer electrolyte fuel cells equipped with conventional ion exchange membranes face limitations in their scope of application.

[0044] Fluorine-based ion exchange membranes, such as Nafion, which are currently known to exhibit the best performance, have limitations due to the complexity of the manufacturing process, technical difficulties, and high costs. Hydrocarbon-based ion exchange membranes, developed as an alternative, still face many technical barriers that need to be overcome due to issues such as low hydrogen ion conductivity under high temperature and low humidity conditions, non-uniform interfacial characteristics, and relatively poor durability.

[0045] Furthermore, these ion exchange membranes require both high ionic conductivity and excellent durability. In particular, during long-term operation of fuel cells, the poor chemical durability of the ion exchange membranes leads to degradation of the fuel cell due to a reduction in electrolyte membrane thickness and the formation of pinholes.

[0046] Radicals generated when a fuel cell operates are known to be a major cause of degradation of the polymer electrolyte membrane. For example, hydrogen peroxide (H2O2) is generated during the reduction reaction of oxygen at the reduction electrode, and hydrogen peroxide radicals (hydroperoxyl radical) (HO2·) and / or hydroxyl radicals (·OH) can be generated from this hydrogen peroxide. Additionally, if oxygen molecules from the air supplied to the reduction electrode pass through the polymer electrolyte membrane and reach the oxidation electrode, hydrogen peroxide is also generated at the oxidation electrode, which can cause hydrogen peroxide radicals and / or hydroxyl radicals. These radicals cause degradation of the ionomer (e.g., a polymer having sulfonic acid groups) contained in the polymer electrolyte membrane, thereby lowering the ionic conductivity of the electrolyte membrane.

[0047] In order to prevent the degradation of a polymer electrolyte membrane (more specifically, an ionomer) caused by radicals, the introduction of a radical scavenger capable of removing said radicals has been proposed.

[0048] However, there is a problem in that the radical scavengers dispersed within the electrolyte membrane in particulate form migrate during the operation of the fuel cell. In other words, as the amount of radical scavengers capable of removing radicals decreases, radical removal is not properly carried out as the operating time of the fuel cell increases, leading to a rapid degradation of the fuel cell's performance.

[0049] Furthermore, metal ions generated through the ionization of radical scavengers are leached by water. Since these metal ions have a very high reduction potential, they oxidize the electrode components (e.g., platinum and / or carbon), causing a degradation in fuel cell performance.

[0050] In this regard, the reinforced composite membrane for a fuel cell according to the present invention further includes a porous support in an electrolyte membrane comprising a hydrogen ion-conducting polymer to improve the physical stability and mechanical properties of the electrolyte membrane, and at the same time, prevents the leaching of a radical scavenger capable of removing metal ions, specifically radicals generated during the fuel cell operation process, from the porous support, thereby maintaining the performance of the fuel cell for a long period and improving its lifespan.

[0051] The porous support (5) serves to enhance the mechanical strength of the reinforced composite membrane and improve dimensional stability by suppressing volume expansion due to moisture. It may use a general porous support used in the industry, or it may be manufactured by chemically curing nanofibers of a polymer precursor produced by electrospinning a solution containing a polymer precursor for forming a porous support.

[0052] It is preferable that the porous support (5) be insoluble in conventional organic solvents, thereby exhibiting excellent chemical resistance, and also facilitate the process of filling ion conductors within the pores of the porous support, and include a hydrocarbon polymer that is hydrophobic and does not cause deformation due to moisture in a high-humidity environment. Examples of the hydrocarbon polymers include nylon, polyvinylidene fluoride (PVDF), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and polylactic acid (PLA). Polyimide (PI), polybenzoxazole (PBO), polybenzimidazole (PBI), polyamideimide (PAI), polyethyleneterephthalate (PET), polyethylene (PE), polytetrafluoroethylene (PTFE), polypropylene (PP), copolymers thereof, or mixtures thereof may be used, and among these, polyimide or polytetrafluoroethylene, which has superior heat resistance, chemical resistance, and shape stability, is preferred.

[0053] In one embodiment, the thickness of the porous support (5) may be 1 to 100 μm, for example, 1 to 75 μm, preferably 1 to 50 μm, and more preferably 3 to 40 μm. If the thickness of the porous support (5) is less than 1 μm, the physical and mechanical properties of the reinforced composite membrane may not be sufficiently secured, and there is a concern that durability and dimensional stability may be reduced. If it exceeds 75 μm, the impregnation efficiency of the hydrogen ion conductive polymer may be lowered, resulting in a decrease in the yield of the membrane. If it exceeds 100 μm, impregnation of the ion conductive polymer may be difficult, and a decrease in hydrogen ion conductivity and a deterioration in membrane performance may occur.

[0054] The porosity of the porous support (5) may be 40 to 95%, for example, 50 to 90%, preferably 55 to 85%. If the porosity of the porous support (5) is less than 40%, the impregnation rate of the hydrogen ion conductive polymer may decrease, and a decrease in membrane performance may occur as a result; if it exceeds 95%, the durability of the reinforced composite membrane may not be sufficiently ensured.

[0055] The reinforced composite membrane (10) may be formed such that the hydrogen ion conductive polymer is impregnated into the porous support (5), or an electrolyte layer (1 and / or 3) containing the hydrogen ion conductive polymer is formed on at least one surface of the porous support (5).

[0056] In the case where the hydrogen ion-conducting polymer is impregnated into the porous support (5), the hydrogen ion-conducting polymer is dispersed in a solvent to prepare a mixed solution, and then the porous support (5) is immersed in the mixed solution to form a reinforced composite membrane in which the hydrogen ion-conducting polymer is impregnated into the porous support (5). The solvent may be water, a hydrophilic solvent, an organic solvent, or a mixture of two or more of these solvents.

[0057] In the case of a reinforced composite membrane (10) having an electrolyte layer (1 and / or 3) containing the hydrogen ion conductive polymer formed on at least one surface of a porous support (5), the membrane can be formed by applying a mixed solution of the hydrogen ion conductive polymer onto at least one surface of the porous support (5) and drying it, or by casting the mixed solution and drying it to form an electrolyte membrane containing the hydrogen ion conductive polymer, and then laminating it with at least one surface of the porous support (5). Additionally, when forming the electrolyte layer (1 and / or 3) into a multilayer structure, the membrane can undergo a process of sequentially applying and drying or laminating mixed solutions with different concentrations and types of hydrogen ion conductive polymers onto the porous support (5). At this time, the application or casting of the mixed solution can be performed through bar coating, comma coating, slot die, screen printing, spray coating, doctor blade, or lamination.

[0058] Alternatively, the reinforced composite membrane (10) may include a form in which an electrolyte layer (1 and / or 3) is formed by laminating an electrolyte membrane containing a hydrogen ion polymer on at least one surface of a porous support (5) impregnated with the hydrogen ion conductive polymer.

[0059] The above drying can be performed by applying heat at 60°C to 100°C for about 1 to 30 minutes, or preferably by applying heat at 70°C to 90°C for about 5 to 15 minutes. At this time, if the drying temperature is less than 60°C, the liquid retention of the hydrogen ion-conducting polymer solution may be reduced, and if it exceeds 100°C, the adhesion with the electrode may be reduced when manufacturing a reinforced composite membrane and / or a membrane-electrode assembly.

[0060] According to one embodiment, the reinforced composite membrane (10) has a structure in which a hydrogen ion-conducting polymer is continuously distributed from the surface of the porous support (5) in the thickness direction of the reinforced composite membrane (10) by impregnating the porous support (5) with a hydrogen ion-conducting polymer, or by providing an electrolyte layer (1 and / or 3) containing a hydrogen ion-conducting polymer on at least one surface of the porous support (5), thereby improving the ion conductivity of the reinforced composite membrane.

[0061] The above hydrogen ion-conducting polymer can be used without special restrictions as long as it is typically used as a hydrogen ion conductor in the electrolyte membrane of a fuel cell. Specifically, a fluorine-based polymer, a hydrocarbon-based polymer, or a mixture thereof that has excellent hydrogen ion conductivity, is cost-effective, and is soluble in organic solvents can be used.

[0062] Specifically, it is preferable to use a polymer having an ion exchange capacity (IEC) of 0.8 meq / g or higher for the above hydrogen ion conductive polymer. By using a polymer with such high ion exchange capacity, the content of the hydrogen ion conductive polymer in the composition for forming a porous support can be reduced, and as a result, the decrease in strength and dimensional stability of the porous support due to the use of the hydrogen ion conductive polymer can be prevented.

[0063] Specific examples include poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), copolymers of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid groups, fluorinated polymers including defluorinated sulfated polyetherketones or mixtures thereof, sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated polyquinoxaline, sulfonated polyketone, and sulfonated sulfonated polyphenylene oxide, sulfonated polyether sulfone, sulfonated polyether ketone, sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, sulfonated polyphenylene sulfide sulfone nitrile, sulfonated polyarylene ether, sulfonated polyarylene ether nitrile,A material selected from the group consisting of hydrocarbon-based polymers including sulfonated polyarylene ether ether nitrile, sulfonated polyarylene ether sulfone ketone, and mixtures thereof, and mixtures thereof may be used.

[0064] In one embodiment, the porous support (5) may further include a compound capable of capturing metal ions.

[0065] The above metal ions are particles capable of removing peroxides or radicals that cause deterioration of the electrolyte membrane and reduce its ion conductivity during the operation of the fuel cell, and may refer to ions of transition metals or noble metals.

[0066] In one embodiment, the metal ion may be a cerium (Ce) ion, manganese (Mn) ion, tungsten (W) ion, cobalt (Co) ion, vanadium (V) ion, nickel (Ni) ion, chromium (Cr) ion, zirconium (Zr) ion, yttrium (Y) ion, iridium (Ir) ion, iron (Fe) ion, titanium (Ti) ion, molybdenum (Mo) ion, lanthanum (La) ion, neodymium (Nd) ion, or a combination thereof, and specifically, taking cerium as an example, cerium trivalent ion (Ce 3+ ) or tetravalent cerium ions (Ce 4+ It can be.

[0067] In one embodiment, the compound capable of capturing the metal ions may be included in an amount preferably from 1 to 50 weight%, more preferably from 1 to 30 weight%, based on the total weight of the porous support. If the content is less than 1 weight%, the metal ion capture efficiency may not be sufficiently achieved, and if it exceeds 50 weight%, the mechanical strength of the porous support may decrease.

[0068] In one embodiment, the compound capable of capturing the metal ion may include polyethylene glycol, polypropylene glycol, polybutylene glycol, crown ether, or a combination thereof, preferably polyethylene glycol, crown ether, or a combination thereof. Although the present invention is not intended to be limited to any particular theory, it may be understood that the metal ion is captured and not eluted from the reinforced composite membrane as the lone pair of electrons of an oxygen atom contained in the polyethylene glycol, polypropylene glycol, polybutylene glycol, or crown ether surrounds the metal ion.

[0069] In one embodiment, the weight-average molecular weight of the polyethylene glycol, polypropylene glycol, and polybutylene glycol, particularly polyethylene glycol, may be 60 to 6,000 g / mol, for example 100 to 4,000 g / mol, preferably 100 to 2,000 g / mol. If the weight-average molecular weight is less than 60 g / mol, there may be a problem of reduced metal ion capture ability, and if it exceeds 6,000 g / mol, there may be a problem of inability to dissolve in the dispersion and difficulty in achieving ionic properties after forming a polymer electrolyte membrane due to reduced fluidity of the polymer, so it is appropriately controlled within the above range.

[0070] In one embodiment, the crown ether may include 12-crown-4-ether, 15-crown-5-ether, 18-crown-6-ether, benzo-15-crown-5-ether, N-phenylazo-15-crown-5-ether, 2-aminomethyl-18-crown-6, or a combination thereof.

[0071] Regarding metal ions (e.g., cerium), a compound capable of capturing said metal ions (e.g., polyethylene glycol, crown ether, etc.) may be included in an amount such that the weight ratio is 1:0.5 or higher, specifically 1:0.8 or higher, more specifically 1:0.8 to 1:3.5, or 1:0.8 to 1:3.3, or 1:0.8 to 1:3. If the compound capable of capturing said metal ions is less than 1:0.5, the capture is not effectively achieved, and while the capture effect improves as the ratio increases, the improvement effect may not be distinct if the ratio is 1:3.5 or higher.

[0073] Another embodiment of the present invention provides a method for manufacturing a reinforced composite membrane for a fuel cell, comprising the steps of: manufacturing a porous support using a composition comprising a precursor of a polymer for forming a porous support and a compound capable of capturing metal ions; and impregnating the porous support with a hydrogen ion-conducting polymer or forming an electrolyte layer comprising a hydrogen ion-conducting polymer on at least one surface of the porous support.

[0074] Looking at each step below, Step 1 is a step of manufacturing a porous support using a precursor of a polymer for forming a porous support and a compound capable of capturing metal ions.

[0075] The step of manufacturing the porous support in Step 1 above can be performed by electrospinning the composition.

[0076] Since the above porous support comprises a hydrocarbon-based polymer that is insoluble in organic solvents as a polymer for forming the porous support, it can be manufactured without dissolving in organic solvents, or it can be manufactured by forming a nanofiber precursor using a precursor of a polymer for forming the porous support that is readily soluble in organic solvents and then proceeding with a predetermined reaction. The precursor of the polymer for forming the porous support can be appropriately selected and used depending on the type of polymer for forming the porous support, and the specific types of the polymer for forming the porous support are as described above.

[0077] For example, a porous support made of PI (Polyimide) can be prepared by the imidation reaction of polyamic acid (PAA). In addition, the polyamic acid can be prepared according to a conventional manufacturing method, and specifically, it can be prepared by mixing a diamine in a solvent, adding a dianhydride thereto, and then polymerizing.

[0078] As the above dianhydride, a compound selected from the group consisting of pyromellyrtic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,4,3',4'-biphenyltetracarboxylic dianhydride (BPDA), and bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride (SiDA), and mixtures thereof may be used. In addition, as the above diamine, 4,4'-oxydianiline, A solvent selected from the group consisting of ODA), p-phenylene diamine (p-PDA), o-phenylene diamine (o-PDA), and mixtures thereof may be used. As a solvent for dissolving the polyamic acid, a solvent selected from the group consisting of m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, diethyl acetate, tetrahydrofuran (THF), chloroform, γ-butyrolactone, and mixtures thereof may be used.

[0079] At this time, it is preferable that the precursor of the polymer for forming the porous support be included at a concentration of 5 to 20 weight percent relative to the total weight of the electrospinning composition. If the concentration of the solution of the electrospinning composition is less than 5 weight percent, spinning does not proceed smoothly, so fiber formation does not occur or fibers with a uniform diameter cannot be produced. On the other hand, if the concentration of the electrospinning composition exceeds 20 weight percent, spinning may not occur or processability may be reduced as the discharge pressure increases rapidly.

[0080] The above-mentioned compound capable of capturing metal ions is the same as previously described, and specifically may include polyethylene glycol, polypropylene glycol, polybutylene glycol, crown ether, or a combination thereof, and it is desirable to appropriately determine the content of the compound capable of capturing metal ions included in the electrospinning composition by considering the content of the final manufactured porous support or the compound capable of capturing metal ions.

[0081] The compound capable of capturing the metal ions may be included in an amount of 1 to 50 parts by weight per 100 parts by weight of the composition, specifically the electrospinning composition, preferably 1 to 20 parts by weight, and more preferably 1 to 10 parts by weight. If the content of the compound capable of capturing the metal ions is less than 1 part by weight per 100 parts by weight of the porous support, the metal ion capture effect may be insufficient and may not be effective in maintaining the durability of the polymer electrolyte, and if it exceeds 50 parts by weight, there may be a problem in that it causes a decrease in the physical properties of the polymer electrolyte membrane due to a decrease in the physical properties of the support.

[0082] Subsequently, a nanofiber web can be manufactured by mixing the above-mentioned polymer precursor for forming a porous support with a compound capable of capturing metal ions to prepare an electrospinning composition and electrospinning the composition, or by preparing an electrospinning composition containing a polymer precursor for forming a porous support and an electrospinning composition containing a compound capable of capturing metal ions, respectively, and then electrospinning them simultaneously through respective spinning nozzles to manufacture a nanofiber web in which the nanofibers of the polymer precursor and the nanofibers of the compound capable of capturing metal ions are intertwined.

[0083] When preparing the above electrospinning composition, a precursor of the polymer for forming the porous support or a compound capable of capturing metal ions can be prepared by dissolving it in a conventional organic solvent such as NMP (N-Methyl-2-Pyrrolidone), DMF (dimethyl formamide), DMAc (dimethyl acetamide), DMSO (dimethyl sulfoxide), or THF (Tetrahydrofuran).

[0084] The above electrospinning can be carried out according to a conventional electrospinning process for manufacturing nanofibers.

[0085] More specifically, a certain amount of the electrospinning composition is supplied to a spinning unit using a metering pump from a solution tank in which the electrospinning composition is stored, and the electrospinning composition is discharged through a nozzle of the spinning unit to form nanofibers of a polymer that are simultaneously dispersed, solidified, and hardened, and additionally, these solidified nanofibers are collected in a collector having a releasing film to produce a fiber assembly. At this time, it is preferable that the electric field strength between the spinning unit and the collector, applied by a high-voltage generator, be 850 to 3,500 V / cm. If the electric field strength is less than 850 V / cm, it is difficult to produce nanofibers of uniform thickness because the precursor solution is not discharged continuously, and it may be difficult to produce a fiber assembly because the nanofibers formed after spinning cannot be smoothly collected in the collector. On the other hand, if the electric field strength exceeds 3,500 V / cm, the nanofibers do not settle accurately on the collector, so a fiber assembly with a normal shape cannot be obtained.

[0086] Through the above spinning process, nanofibers having a uniform fiber diameter, preferably an average diameter of 0.01 to 5 μm, are produced, and the nanofibers are randomly arranged to form a fiber aggregate, i.e., a web.

[0087] Additionally, a chemical curing process can be performed on the manufactured nanofiber web.

[0088] Typically, curing of hydrocarbon-based polymer precursors is achieved through heat treatment; however, since the nanofiber web in the present invention contains compounds capable of capturing metal ions, such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and crown ether, if a curing process involving excessive heat treatment is performed, the compounds capable of capturing metal ions may be denatured, evaporated, or decomposed by heat. Accordingly, the present invention induces curing of the polymer precursor by impregnating the nanofiber web obtained after electrospinning with a curing agent. At this time, curing agents such as acetic anhydride, pyridine, triethylamine, toluenesulfonic acid, hydroxybenzyl alcohol, aminophenol, hydroxybenzaldehyde, and aminobenzoic acid are used. The curing agents usable in the present invention are not limited to the aforementioned compounds, and it is preferable to select them appropriately depending on the type of polymer precursor used for forming the porous support for the manufacture of the porous support.

[0089] It is preferable that the content of the above curing agent be appropriately determined according to the content of the polymer precursor included in the electrospinning composition.

[0090] In the above curing process, curing occurs to convert the polymer precursor into a polymer for forming a porous support. For example, if the nanofiber or fiber assembly is composed of a polyimide precursor during the electrospinning, it is converted into polyimide through imidization by chemical curing.

[0091] Step 2 is a step of impregnating a hydrogen ion-conducting polymer into the porous support prepared in Step 1, or forming an electrolyte layer containing a hydrogen ion-conducting polymer on at least one surface of the porous support.

[0092] In one embodiment, step 2 may include a step of preparing a mixed solution in which the hydrogen ion-conducting polymer is dispersed in a solvent and a step of impregnating the porous support with the mixed solution, but is not limited thereto, and various methods known in the art, such as a spray process, a screen printing process, or a doctor blade process, may be used. When using the impregnation process, it is preferable to perform the impregnation process 1 to 5 times for 5 to 30 minutes at room temperature.

[0093] The above solvent may be one that can effectively dissolve the hydrogen ion-conducting polymer, such as N-methyl-2-pyrrolidinone (NMP), dimethylformamide (DMF), or dimethyl acetamide (DMA), but is not limited to these.

[0094] The above hydrogen ion conductive polymer can be the same as that described above.

[0095] In addition, in one embodiment, step 2 may include the step of preparing a mixed solution by dispersing the hydrogen ion-conducting polymer in a solvent, the step of forming an electrolyte membrane by casting and drying the mixed solution, and the step of laminating the electrolyte membrane with the porous support.

[0096] In the step of preparing the reinforced composite membrane above, the description regarding the application and casting of the solvent and mixed solution for dispersing the hydrogen ion-conducting polymer is as described above, so a repetitive description is omitted.

[0097] It is preferable that the above hydrogen ion conductive polymer be appropriately determined by considering the content of the hydrogen ion conductive polymer included in the reinforced composite membrane. Specifically, it may be included in the hydrogen ion conductive polymer-containing solution in an amount of 5 to 40 weight%. If the hydrogen ion conductive polymer is included in the hydrogen ion conductive polymer-containing solution in an amount of less than 5 weight%, the hydrogen ion conductive polymer may not be sufficiently filled into the pores of the porous support and may form empty spaces, and if the hydrogen ion conductive polymer exceeds 40 weight%, the viscosity of the hydrogen ion conductive polymer-containing solution may be too high and may not be filled into the pores of the porous support.

[0098] After filling with the above-mentioned hydrogen ion conductive polymer-containing solution, the organic solvent in the hydrogen ion conductive polymer-containing solution is removed so that the hydrogen ion conductive polymer fills the pores of the porous support. Accordingly, the method for manufacturing a reinforced composite membrane for a fuel cell according to the present invention may further include a process of removing the organic solvent after filling with the hydrogen ion conductive polymer, and the organic solvent removal process may be performed by drying in a vacuum oven at 60 to 150°C for 2 to 15 hours.

[0099] The reinforced composite membrane manufactured by the above-described manufacturing method for hydrogen ion-conducting polymers has excellent hydrogen ion conductivity and can exhibit improved hydrogen ion conductivity when used as a polymer electrolyte membrane in a membrane-electrode assembly for a fuel cell.

[0100] According to another embodiment of the present invention, a membrane-electrode assembly and a fuel cell comprising the reinforced composite membrane are provided.

[0101] Specifically, the membrane-electrode assembly comprises an anode electrode and a cathode electrode positioned opposite each other, and the reinforced composite membrane positioned between the anode electrode and the cathode electrode.

[0102] FIG. 2 is a schematic cross-sectional view of a membrane-electrode assembly according to an embodiment of the present invention. Referring to FIG. 2, the membrane-electrode assembly (100) includes the reinforced composite membrane (50) and the fuel cell electrodes (20, 20') respectively disposed on both sides of the reinforced composite membrane (50). The electrodes (20, 20') include an electrode substrate (40, 40') and a catalyst layer (30, 30') formed on the surface of the electrode substrate (40, 40'). In order to facilitate material diffusion from the electrode substrate (40, 40'), the electrodes (20, 20') may further include a microporous layer (not shown) containing conductive fine particles such as carbon powder or carbon black between the electrode substrate (40, 40') and the catalyst layer (30, 30').

[0103] In the above membrane-electrode assembly (100), the electrode (20) disposed on one side of the reinforced composite membrane (50) and causing an oxidation reaction that generates hydrogen ions and electrons from fuel delivered through the electrode substrate (40) to the catalyst layer (30) is called the anode electrode, and the electrode (20') disposed on the other side of the reinforced composite membrane (50) and causing a reduction reaction that generates water from hydrogen ions supplied through the reinforced composite membrane (50) and an oxidant delivered through the electrode substrate (40') to the catalyst layer (30') is called the cathode electrode.

[0104] The catalyst layer (30, 30') of the anode and cathode electrodes (20, 20') comprises a catalyst. Any catalyst that participates in the reaction of the cell and can be used as a catalyst for a fuel cell can be used. Specifically, a platinum-based metal can preferably be used.

[0105] The above platinum-based metal may include one selected from the group consisting of platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), platinum-M alloy (wherein M is one or more selected from the group consisting of palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), gallium (Ga), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), zinc (Zn), tin (Sn), molybdenum (Mo), tungsten (W), lanthanum (La), and rhodium (Rh)), non-platinum alloy, and combinations thereof; more preferably, a combination of two or more metals selected from the group consisting of platinum-based catalyst metals may be used, but is not limited thereto, and any platinum-based catalyst metal available in the field of the present art may be used without limitation.

[0106] Specifically, the platinum alloy may be used alone or in a mixture of two or more selected from the group consisting of Pt-Pd, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ru, Pt-Ru-W, Pt-Ru-Mo, Pt-Ru-Rh-Ni, Pt-Ru-Sn-W, Pt-Co, Pt-Co-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-Co-S, Pt-Co-P, Pt-Fe, Pt-Fe-Ir, Pt-Fe-S, Pt-Fe-P, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Ni, Pt-Ni-Ir, Pt-Cr, Pt-Cr-Ir, and combinations thereof.

[0107] In addition, the above-mentioned non-platinum alloy may be used alone or in a mixture of two or more selected from the group consisting of Ir-Fe, Ir-Ru, Ir-Os, Co-Fe, Co-Ru, Co-Os, Rh-Fe, Rh-Ru, Rh-Os, Ir-Ru-Fe, Ir-Ru-Os, Rh-Ru-Fe, Rh-Ru-Os, and combinations thereof.

[0108] These catalysts can be used as the catalyst itself (black) or supported on a carrier.

[0109] The above carrier can be selected from carbon-based carriers, porous inorganic oxides such as zirconia, alumina, titania, silica, ceria, zeolites, etc. The above carbon-based carrier may be selected from graphite, super P, carbon fiber, carbon sheet, carbon black, Ketjen black, Denka black, acetylene black, carbon nanotube (CNT), carbon sphere, carbon ribbon, fullerene, activated carbon, carbon nanofiber, carbon nanowire, carbon nanoball, carbon nanohorn, carbon nanocage, carbon nanoring, ordered nano- / meso-porous carbon, carbon aerogel, mesoporous carbon, graphene, stabilized carbon, activated carbon, and one or more combinations thereof, but is not limited thereto, and any carrier available in the field of the art may be used without limitation.

[0110] The catalyst particles may be located on the surface of the carrier, or they may penetrate into the carrier while filling the internal pores of the carrier.

[0111] When using a precious metal supported on the above-mentioned carrier as a catalyst, commercially available products may be used, or a product manufactured by supporting the precious metal on the carrier may be used. Since the process of supporting the precious metal on the above-mentioned carrier is widely known in the field, a detailed description in this specification is omitted, as it is easily understood by those skilled in the field.

[0112] The catalyst particles may be contained in an amount of 20% to 80% by weight relative to the total weight of the catalyst electrode (30, 30'). If the amount is less than 20% by weight, there may be a problem with reduced activity, and if the amount exceeds 80% by weight, the active area may be reduced due to the aggregation of the catalyst particles, which conversely may reduce the catalyst activity.

[0113] In addition, the catalyst electrode (30, 30') may include a binder to improve the adhesion of the catalyst electrode (30, 30') and to transport hydrogen ions. It is preferable to use an ion conductor having ion conductivity as the binder, and since the description of the ion conductor is the same as above, a repetitive description is omitted.

[0114] However, the above ion conductor may be used in the form of a single material or a mixture, and may also be used with a non-conductive compound for the purpose of further improving adhesion to the reinforced composite membrane (50). It is preferable to adjust the amount used to suit the intended purpose.

[0115] One or more of the above-mentioned nonconductive compounds may be used, selected from the group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), dodecylbenzenesulfonic acid, and sorbitol.

[0116] The binder may be included in an amount of 20% to 80% by weight relative to the total weight of the catalyst electrode (30, 30'). If the content of the binder is less than 20% by weight, the generated ions may not be properly transferred, and if it exceeds 80% by weight, the pores may be insufficient, making it difficult to supply hydrogen or oxygen (air) and reducing the active surface area available for reaction.

[0117] As the electrode substrate (40, 40'), a porous conductive substrate may be used to ensure a smooth supply of hydrogen or oxygen. Representative examples may include carbon paper, carbon cloth, carbon felt, or metal cloth (referring to a porous film composed of a metal cloth in a fibrous state or a metal film formed on the surface of a cloth formed of polymer fibers), but are not limited thereto. In addition, it is preferable to use an electrode substrate (40, 40') that has been treated with a water-repellent fluorine-based resin to prevent a decrease in reactant diffusion efficiency caused by water generated during the operation of the fuel cell. As the fluorine-based resin, polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonylfluoride alkoxyvinyl ether, fluorinated ethylene propylene, polychlorotrifluoroethylene, or copolymers thereof may be used.

[0118] Additionally, a microporous layer may be further included to enhance the reactant diffusion effect in the electrode substrate (40, 40'). This microporous layer may generally include a conductive powder with a small particle size, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotube, carbon nanowire, carbon nanohorn, or carbon nanoring.

[0119] The above microporous layer is prepared by coating a composition comprising a conductive powder, a binder resin, and a solvent onto the electrode substrate (40, 40'). Preferably, the binder resin may be polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxyvinyl ether, polyvinyl alcohol, cellulose acetate, or copolymers thereof. Preferably, the solvent may be an alcohol such as ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, water, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, etc. Depending on the viscosity of the composition, the coating process may be performed using a screen printing method, a spray coating method, or a coating method using a doctor blade, but is not limited thereto.

[0120] The above membrane-electrode assembly (100) can be manufactured according to a conventional method for manufacturing a membrane-electrode assembly for a fuel cell, except that the reinforced composite membrane (50) according to the present invention is used as the reinforced composite membrane (50).

[0121] A fuel cell according to another embodiment of the present invention may include the membrane-electrode assembly (100).

[0122] Figure 3 is a schematic diagram illustrating the overall configuration of the fuel cell.

[0123] Referring to FIG. 3 above, the fuel cell (200) includes a fuel supply unit (210) that supplies a mixed fuel in which fuel and water are mixed, a reforming unit (220) that reforms the mixed fuel to generate a reformed gas containing hydrogen gas, a stack (230) that generates electrical energy by causing an electrochemical reaction between the reformed gas containing hydrogen gas supplied from the reforming unit (220) and an oxidizing agent supply unit (240) that supplies an oxidizing agent to the reforming unit (220) and the stack (230).

[0124] The stack (230) comprises a plurality of unit cells that generate electrical energy by inducing an oxidation / reduction reaction between a reforming gas containing hydrogen gas supplied from the reforming unit (220) and an oxidizing agent supplied from the oxidizing agent supply unit (240).

[0125] Each unit cell refers to a unit cell that generates electricity and includes a membrane-electrode assembly that oxidizes / reduces oxygen in an oxidant and a reforming gas containing hydrogen gas, and a separator (also called a bipolar plate, hereinafter referred to as a 'separator') for supplying the reforming gas containing hydrogen gas and the oxidant to the membrane-electrode assembly. The separator is positioned on both sides of the membrane-electrode assembly with the membrane-electrode assembly at the center. At this time, the separator located at the outermost side of the stack is specifically referred to as an end plate.

[0126] Among the above separator plates, the end plate is provided with a pipe-shaped first supply pipe (231) for injecting a reforming gas containing hydrogen gas supplied from the reforming unit (220) and a pipe-shaped second supply pipe (232) for injecting oxygen gas, and the other end plate is provided with a first discharge pipe (233) for discharging to the outside a reforming gas containing hydrogen gas that is finally unreacted and remaining in a plurality of unit cells, and a second discharge pipe (234) for discharging to the outside an oxidizing agent that is finally unreacted and remaining in the above unit cells.

[0127] In the above fuel cell, except for the use of a membrane-electrode assembly (100) according to one embodiment of the present invention, the separator, fuel supply unit, and oxidant supply unit constituting the electric generation unit are used in a conventional fuel cell, so a detailed description is omitted in this specification.

[0129] Specific embodiments of the present invention are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the present invention and do not limit the present invention. Furthermore, details not described herein can be sufficiently technically inferred by a person skilled in the art, so their description is omitted.

[0131] Preparation Example 1

[0132] (1) A polytetrafluoroethylene / THF spinning solution containing 1 part by weight of polyethylene glycol (Mw: 2,000) per 100 parts by weight of the total spinning solution, with a concentration of 25% by weight, is applied to a spinning nozzle and electrospun under a voltage of 30 kV to form a polytetrafluoroethylene porous support.

[0133] (2) An ion conductor solution containing 20 wt% of Nafion dissolved as a hydrogen ion conductive polymer and 2 wt% of Ce(NO3)3 in Nafion was coated twice using a doctor blade onto the prepared porous support. After the first coating, the support was bonded, and a second coating was performed to form a reinforced composite membrane. Subsequently, the reinforced composite membrane was prepared by drying at 80°C for 1 hour and then drying in a vacuum oven for 1 hour. (PEG weight ratio in support: 4%)

[0135] Preparation Example 2

[0136] A reinforced composite membrane was prepared in the same manner as in Preparation Example 1, except that the polyethylene glycol content was included at 0.2 parts by weight per 100 parts by weight of the total spinning solution. (PEG weight ratio in support 0.8%)

[0138] Preparation Example 3

[0139] A reinforced composite membrane was prepared in the same manner as in Preparation Example 1, except that the polyethylene glycol content was included at 2 parts by weight per 100 parts by weight of the total spinning solution. (PEG weight ratio in support: 8%)

[0141] Preparation Example 4

[0142] A reinforced composite membrane was prepared in the same manner as in Preparation Example 1, except that the polyethylene glycol content was 5 parts by weight per 100 parts by weight of the total spinning solution. (PEG weight ratio in support: 20%)

[0144] Preparation Example 5

[0145] A reinforced composite membrane was prepared in the same manner as in Preparation Example 1, except that the polyethylene glycol content was included at 30 parts by weight per 100 parts by weight of the total spinning solution. (PEG weight ratio in support 54.5%)

[0147] Preparation Example 6

[0148] A reinforced composite membrane was prepared in the same manner as in Preparation Example 1, except that a polyphenylene sulfide / THF spinning solution was used instead of a polytetrafluoroethylene / THF spinning solution. (PEG weight ratio in support: 4%)

[0150] Preparation Example 7

[0151] A reinforced composite membrane was prepared in the same manner as in Preparation Example 6 above, except that the polyethylene glycol content was included at 2 parts by weight per 100 parts by weight of the total spinning solution. (PEG weight ratio in support: 8%)

[0153] Preparation Example 8

[0154] A reinforced composite membrane was prepared in the same manner as in Preparation Example 6 above, except that the polyethylene glycol content was included at 5 parts by weight per 100 parts by weight of the total spinning solution. (PEG weight ratio in support 20%)

[0156] Preparation Example 9

[0157] A mixture of 117 g of 2,5-dichlorobenzene, 32.0 g of sulfur, and 47.5 g (20 mol%) of 2,5-dichlorobenzoic acid was heated from 230°C to 300°C and polymerized for a total of 8 hours under stepwise reduced pressure from 170 torr to 1 torr or less to produce a PPS copolymer having carboxyl groups as repeating units. 1 wt% of 2-Aminomethyl-18-crown-6 was introduced into this PPS polymer via a dehydration condensation reaction. The polymer thus prepared was applied to the solution in place of the polyphenylene sulfide of Preparation Example 6. A reinforced composite membrane was prepared in the same manner as Preparation Example 6, except that the solution did not contain polyethylene glycol.

[0159] Comparative Manufacturing Example 1

[0160] A reinforced composite membrane was prepared in the same manner as in Preparation Example 1, except that a spinning solution not containing polyethylene glycol was used.

[0162] Comparative Manufacturing Example 2

[0163] A reinforced composite membrane was prepared in the same manner as in Preparation Example 6, except that a spinning solution not containing polyethylene glycol was used.

[0165] Examples 1 to 9 and Comparative Examples 1 to 2

[0166] A membrane-electrode assembly was prepared by forming an electrode layer on the reinforced composite membranes prepared in Preparation Examples 1 to 9 and Comparative Preparation Examples 1 to 2 using a decal transfer method. At this time, the catalyst layer of the electrode was formed by applying a composition for forming a catalyst layer containing a Pt / carbon catalyst to a release film and drying it; then, the release film coated with the catalyst layer was positioned on both sides of the reinforced composite membrane so that the catalyst layer and the reinforced composite membrane faced each other, and then 5 kg / cm² 2 A catalyst layer was transferred to both sides of a reinforced composite membrane by hot pressing at a pressure of 100°C and a temperature of 100°C. Subsequently, a membrane-electrode assembly was manufactured by attaching a gas fusion layer (GDL) to both sides of the reinforced composite membrane to which the catalyst layer was bonded.

[0168] Evaluation Example 1 - Battery Performance Evaluation

[0169] The membrane-electrode assemblies prepared according to the above examples and comparative examples were evaluated. The output performance of the membrane-electrode assemblies was evaluated through IV measurements. Specifically, to verify the output performance under actual fuel cell operating conditions, the membrane-electrode assemblies were connected to a fuel cell unit cell evaluation device and the temperature was maintained at 65°C. Hydrogen (100 %RH) and air (100 %RH) were supplied to the anode and cathode, respectively, in amounts corresponding to Stoichiometry 1.2 / 2.0. The current density at 0.6V was measured, and a higher value indicates superior output performance. The evaluation results are shown in Table 1 below.

[0171] Evaluation Example 2 - Dimensional Stability Evaluation

[0172] The reinforced composite membranes prepared in Preparation Examples 1 to 8 and Comparative Preparation Examples 1 to 2 were dried in a vacuum oven at 80°C for 12 hours and their dimensions were measured. After immersion in distilled water at room temperature for 24 hours, the dimensions were measured again, and the ratio of dimensions before and after water absorption was compared. A lower rate of dimensional change indicates higher stability. The evaluation results are shown in Table 1 below.

[0174] Evaluation Example 3 - Chemical Durability Evaluation

[0175] The membrane-electrode assemblies prepared according to the above examples and comparative examples were evaluated. The evaluation cell was placed in an OCV state, and the cell voltage was measured at regular time intervals to calculate the rate of decrease relative to the initial OCV. Measurements were performed using a Scribner 850 fuel cell test system (evaluations were conducted under conditions of 90°C, 30%RH, and 50kPa). Specifically, the OCV(V) / initial OCV(V) was measured over time (hr) every 24 hours. The evaluation was terminated when this ratio was 0.8 or less, and the measurement time was used as the criterion for durability. The evaluation results are shown in Table 1 below.

[0177] Battery performance evaluation Dimensional change Chemical durability Comparative Example 1 998 6 504 Comparative Example 2 1007 11 480 Example 1 998 7 528 Example 2 1009 6 504 Example 3 1000 7 528 Example 4 997 8 552 Example 5 1003 16 552 Example 6 1010 12 504 Example 7 1012 12 504 Example 8 1015 14 528 Example 9 1010 12 504

[0179] From Table 1 above, it can be seen that chemical durability can be improved compared to comparative examples when using reinforced composite membranes according to the embodiments of the present invention. However, in the case of Example 2, the polyethylene glycol content was low, so it was not sufficiently coated on the support, and thus the capture efficiency was not fully achieved, and in the case of Example 5, the polyethylene glycol content was high, so the strength of the support was somewhat reduced.

[0181] Although preferred embodiments of the present invention have been described in detail above, the above-described embodiments are presented as specific examples of the present invention and are not intended to limit the present invention. Furthermore, various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the claims set forth below also fall within the scope of the present invention. Explanation of the symbols

[0183] 10, 50: Reinforced composite membrane 1,3: Electrolyte layer 5: Porous support 20, 20': Electrode 30, 30': Catalyst layer 40, 40': Electrode material 100: Membrane-electrode assembly 200: Fuel cell 210: Fuel supply unit 220: Reforming unit 230: Stack 231: First Supply Pipe 232: Second supply pipe 233: First discharge pipe 234: Second discharge pipe 240: Oxidizer supply unit

Claims

Claim 1 A reinforced composite membrane for a fuel cell comprising a porous support and a hydrogen ion-conducting polymer, wherein the reinforced composite membrane comprises an electrolyte layer comprising the hydrogen ion-conducting polymer on at least one surface of the porous support, and the porous support further comprises a compound capable of capturing metal ions, wherein the compound capable of capturing metal ions comprises polyethylene glycol, polypropylene glycol, polybutylene glycol, or a combination thereof, and is included in an amount of 1 to 50 weight percent based on the total weight of the porous support. Claim 2 delete Claim 3 A reinforced composite membrane for a fuel cell according to claim 1, wherein the weight-average molecular weight of the polyethylene glycol, polypropylene glycol, and polybutylene glycol is 60 to 6,000 g / mol. Claim 4 delete Claim 5 delete Claim 6 A reinforced composite membrane for a fuel cell according to claim 1, wherein the metal ions include cerium (Ce) ions, manganese (Mn) ions, tungsten (W) ions, cobalt (Co) ions, vanadium (V) ions, nickel (Ni) ions, chromium (Cr) ions, zirconium (Zr) ions, yttrium (Y) ions, iridium (Ir) ions, iron (Fe) ions, titanium (Ti) ions, molybdenum (Mo) ions, lanthanum (La) ions, neodymium (Nd) ions, or a combination thereof. Claim 7 A reinforced composite membrane for a fuel cell according to claim 1, wherein the thickness of the porous support is 1 to 100 μm. Claim 8 A method for manufacturing a reinforced composite membrane for a fuel cell, comprising: a step of manufacturing a porous support using a composition comprising a precursor of a polymer for forming a porous support and a compound capable of capturing metal ions; and a step of forming an electrolyte layer comprising a hydrogen ion-conducting polymer on at least one surface of the porous support; wherein the compound capable of capturing metal ions comprises polyethylene glycol, polypropylene glycol, polybutylene glycol, or a combination thereof, and is included in an amount of 1 to 50 parts by weight per 100 parts by weight of the composition. Claim 9 A method for manufacturing a reinforced composite membrane for a fuel cell, wherein, in claim 8, the polymer for forming the porous support is a hydrocarbon-based polymer insoluble in organic solvents. Claim 10 delete Claim 11 delete Claim 12 A method for manufacturing a reinforced composite membrane for a fuel cell, wherein, in claim 8, the step of manufacturing the porous support is performed by electrospinning the composition. Claim 13 A method for manufacturing a reinforced composite membrane for a fuel cell, wherein, in claim 8, the step of forming an electrolyte layer comprising the hydrogen ion-conducting polymer comprises: a step of preparing a mixed solution by dispersing the hydrogen ion-conducting polymer in a solvent; a step of forming an electrolyte layer by casting and drying the mixed solution; and a step of laminating the electrolyte layer with the porous support. Claim 14 A membrane-electrode assembly comprising an anode electrode and a cathode electrode positioned opposite each other, and a reinforced composite membrane for a fuel cell according to claim 1 positioned between the anode electrode and the cathode electrode. Claim 15 A fuel cell comprising a membrane-electrode assembly according to paragraph 14.

Images