Membrane-electrode assembly and fuel cell including same

Abstract

One embodiment of the present invention provides a membrane-electrode assembly that simultaneously improves performance and durability. The membrane-electrode assembly includes a polymer electrolyte membrane and a catalyst layer disposed on at least one surface of the polymer electrolyte membrane, the catalyst layer comprising platelet mesoporous carbon having short-axis pores and no metal nanoparticles supported thereon, and the catalyst layer is a single layer.

Description

[Technical Field]

[0001] The present invention relates to a membrane-electrode assembly and a fuel cell including the same, and more particularly to a membrane-electrode assembly and a fuel cell including the same that simultaneously improves performance and durability. [Background technology]

[0002] Fuel cells are cells that directly convert chemical energy generated by the oxidation of fuel into electrical energy, and are attracting attention as a next-generation energy source due to their high energy efficiency and environmentally friendly characteristics such as low pollutant emissions. Such fuel cells generally have a structure in which an anode and a cathode are formed on either side of a polymer electrolyte membrane, and this structure is called a membrane electrode assembly (MEA).

[0003] Fuel cells are divided into alkaline electrolyte fuel cells, polymer electrolyte membrane fuel cells (PEMFC), etc. depending on the type of electrolyte membrane. Among them, polymer electrolyte membrane fuel cells are attracting attention as portable, vehicular, and home power sources due to their advantages such as a low operating temperature of less than 100°C, fast start-up and response characteristics, and excellent durability.

[0004] A typical example of such a polymer electrolyte membrane fuel cell is a proton exchange membrane fuel cell (PEMFC), which uses hydrogen gas as fuel.

[0005] To summarize the reactions that occur in a polymer electrolyte membrane fuel cell, first, when fuel such as hydrogen gas is supplied to the oxidizing electrode (or anode), hydrogen gas is oxidized at the oxidizing electrode to generate hydrogen ions and electrons. The generated hydrogen ions are transported to the reducing electrode through the polymer electrolyte membrane, and the generated electrons are transported to the reducing electrode (or cathode) through an external circuit. Oxygen gas is supplied to the reducing electrode, and the oxygen gas combines with the hydrogen ions and electrons to generate water through a reduction reaction. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide a membrane-electrode assembly in which performance and durability are both improved.

[0007] Another object of the present invention is to provide a membrane-electrode assembly that includes a catalyst layer that facilitates mass transfer.

[0008] The objects of the present invention are not limited to those mentioned above, and other objects and advantages of the present invention not mentioned above will be understood from the following description and will become more clearly understood by the examples of the present invention. Furthermore, it will be easily understood that the objects and advantages of the present invention can be realized by the means and combinations thereof as claimed. [Means for solving the problem]

[0009] To achieve the above object, one embodiment of the present invention provides a membrane-electrode assembly including a polymer electrolyte membrane and a catalyst layer disposed on at least one surface of the polymer electrolyte membrane, the catalyst layer including platelet mesoporous carbon on which metal nanoparticles are not supported, and the catalyst layer is a single layer.

[0010] To achieve the above object, yet another embodiment of the present invention can provide a fuel cell including the membrane-electrode assembly.

[0011] The above summary of the invention is not an exhaustive list of the features of the invention, and the various features and advantages thereof will be more fully understood with reference to the following specific examples. [Effects of the Invention]

[0012] According to one embodiment of the present invention, it is possible to provide a membrane-electrode assembly that simultaneously improves performance and durability. Also, according to one embodiment of the present invention, it is possible to provide a membrane-electrode assembly including a catalyst layer that has improved performance due to improved mass transport and ion transport paths due to a pore structure and improved porosity throughout the catalyst layer, and improved durability due to reduced catalyst deterioration caused by easy mass transport even when the fuel cell is operated for a long period of time.

[0013] In addition to the above-mentioned effects, specific effects of the present invention will be described below while explaining specific details for carrying out the invention. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing plate-shaped mesoporous carbon according to various embodiments of the present invention. FIG. [Figure 2] 1A-1C are schematic diagrams illustrating shapes within a catalyst layer according to various embodiments of the present invention. [Figure 3] 1 is a schematic diagram illustrating a fuel cell according to an embodiment of the present invention; [Figure 4] 1 is a UHR-SEM photograph of plate-like mesoporous carbon having aligned nanofibers according to Synthesis Example 1-1. [Figure 5] 1 is a UHR-SEM photograph of plate-shaped mesoporous carbon having aligned nanotubes according to Synthesis Example 2-1. [Figure 6] 1 is a SEM photograph of a cross section of a catalyst layer containing plate-like mesoporous carbon on which metal nanoparticles are not supported according to Example 1-2. [Figure 7]1 is a UHR-SEM photograph of a catalyst layer containing plate-like mesoporous carbon on which metal nanoparticles are not supported according to Example 2-2. [Figure 8] 1 shows the performance evaluation results of the membrane-electrode assemblies manufactured in the examples and comparative examples under the conditions of 80° C., 100% RH, and normal pressure. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, each component of the present invention will be described in more detail so that a person having ordinary skill in the art to which the present invention pertains can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited by the following content.

[0016] One embodiment of the present invention provides a membrane-electrode assembly including a polymer electrolyte membrane and a catalyst layer disposed on at least one surface of the polymer electrolyte membrane, the catalyst layer comprising platelet mesoporous carbon without metal nanoparticles supported thereon, the catalyst layer being a single layer. According to one embodiment of the present invention, the use of platelet mesoporous carbon, which has a large specific surface area and a short-axis pore morphology to facilitate mass and ion transport, can simultaneously improve the performance and durability of the membrane-electrode assembly.

[0017] The configuration of the present invention will be described in more detail below with reference to FIGS.

[0018] FIG. 1 is a schematic diagram showing plate-shaped mesoporous carbon according to various embodiments of the present invention.

[0019] FIG. 2 is a schematic diagram illustrating the internal geometry of a catalyst layer according to various embodiments of the present invention.

[0020] 1 and 2, the membrane-electrode assembly according to the present invention includes a polymer electrolyte membrane, which may be a commercially available polymer electrolyte membrane in the art, and may include, for example, an ion conductor.

[0021] The catalyst layer 20 according to the present invention may be disposed on at least one side of the polymer electrolyte membrane. The catalyst layer 20 may include platelet mesoporous carbon without metal nanoparticles (or metal catalyst particles) supported thereon. That is, the catalyst layer 20 according to one embodiment of the present invention may be disposed on one side of the polymer electrolyte membrane, and a commercial catalyst layer may be disposed on the other side opposite the one side. The catalyst layer 20 according to another embodiment of the present invention may be disposed on both sides of the polymer electrolyte membrane. Conventional fuel cells suffer from reduced performance due to irregular mass and ion transport pathways during operation, and membrane-electrode assemblies are prone to deterioration over long periods of operation. According to one embodiment of the present invention, improved mass and ion transport pathways due to a short-axis pore structure and increased porosity throughout the catalyst layer improve performance. Furthermore, the ease of mass transport during long-term fuel cell operation prevents deterioration and enhances the durability of the membrane-electrode assembly, thereby enhancing durability.

[0022] According to one embodiment of the present invention, an ionomer layer IL can be coated on the surfaces and pores of the mesoporous carbon plates 20a and 20b. According to one embodiment of the present invention, coating the surfaces and pores of the mesoporous carbon plates 20a and 20b with the ionomer layer IL not only further increases ion conductivity through a shorter ion transport path, but also improves interfacial adhesion between the polymer electrolyte membrane and the electrode, resulting in significantly improved durability of the membrane-electrode assembly. The thickness of the ionomer layer IL may be 1 to 7 nm (nanometers), specifically 1.5 to 6 nm (nanometers), and more specifically 2 to 5 nm (nanometers). If the thickness of the ionomer layer is less than the above range, ion conductivity may be reduced. If the thickness exceeds the above range, only ion transport may be improved, while mass transport may be hindered.

[0023] Specifically, the ionomer layer IL may include a first ionomer. The equivalent weight (EW) of the first ionomer may be 600 to 1,200 g / eq. When the equivalent weight of the first ionomer is within this range, the interfacial adhesion between the polymer electrolyte membrane and the first catalyst layer may be improved, and both ion conductivity and catalyst durability may be enhanced.

[0024] The first ionomer may be any one selected from the group consisting of fluorine-based ionomers, hydrocarbon-based ionomers, and mixtures thereof.

[0025] The fluorine-based ionomer may be, for example, any one selected from the group consisting of a fluorine-containing polymer containing fluorine in the main chain, such as poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, a polystyrene-graft-ethylene-tetrafluoroethylene copolymer, a polystyrene-graft-polytetrafluoroethylene copolymer, and mixtures thereof.

[0026] Examples of the hydrocarbon ionomer include sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (S-PEEK), sulfonated polybenzimidazole (S-PBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated polyquinoxaline, sulfonated polyketone, sulfonated polyphenylene oxide, sulfonated polyethersulfone, and sulfonated polyethersulfone. 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 nitrilenitrile), sulfonated polyarylene ether ether nitrile, sulfonated polyarylene ether sulfone ketone, and mixtures thereof.

[0027] To coat the surface of the plate-like mesoporous carbon with an ionomer layer IL, a solid-state resonant acoustic vibration mixing method or a method of homogenizing the surface of the plate-like mesoporous carbon using a ball mill, homogenizing mixer, high-pressure disperser, etc. may be used. For example, the ionomer layer may be coated by homogenizing a polymer powder containing the first ionomer and the plate-like mesoporous carbon at a weight ratio (polymer powder:plate-like mesoporous carbon) of 1:20 to 1:200 using a resonant acoustic vibration mixer at a gravitational acceleration of 40 to 100 G for 3 to 60 minutes, followed by heat treatment at 100 to 160°C for 30 to 100 minutes. However, the technical concept of the present invention is not limited thereto, and various methods for coating the surface of the plate-like mesoporous carbon with an ionomer layer may be used.

[0028] In the plate-shaped mesoporous carbon according to one embodiment of the present invention, pores contained in nanofibers or nanotubes may extend perpendicular to the surface of the polymer electrolyte membrane. The nanofibers and nanotubes may each independently have a height of 50 to 600 nm (nanometers). When the heights of the nanofibers and nanotubes are within the above ranges, the durability and performance of the membrane-electrode assembly can be improved simultaneously.

[0029] In another embodiment of the present invention, the pores of the nanofibers or nanotubes of the plate-shaped mesoporous carbon may extend non-perpendicularly to the surface of the polymer electrolyte membrane. When the pores of the plate-shaped mesoporous carbon extend non-perpendicularly to the surface of the polymer electrolyte membrane, the pore shape can be maintained within the catalyst layer, thereby improving durability.

[0030] The plate-like mesoporous carbon according to the present invention may have nanofibers or nanotubes aligned in the minor axis direction. Specifically, the plate-like mesoporous carbon 20a having aligned nanofibers may have mesopores of 2 to 20 nm (nanometers) in size and a height of 50 to 600 nm (nanometers), and the plate-like mesoporous carbon 20b having aligned nanotubes may have mesopores of 2 to 30 nm (nanometers) in size and a height of 50 to 600 nm (nanometers). The plate-like mesoporous carbons having the nanofibers and nanotubes in a plate-like shape may each independently have a width or length of 100 to 1,500 nm (nanometers), specifically 200 to 1,200 nm (nanometers), and more specifically 300 to 1,000 nm (nanometers).

[0031] Referring to FIG. 2, the catalyst layer according to the present invention may further include a support and metal nanoparticles supported on the support.

[0032] The support may be, for example, a carbon-based support, a porous inorganic oxide, a zeolite, or a combination thereof. The carbon-based support may be, for example, graphite, Super P, carbon fiber, a carbon sheet, carbon black, Ketjen Black, Denka Black, acetylene black, carbon nanotubes (CNTs), carbon spheres, carbon ribbons, fullerenes, activated carbon, carbon nanofibers, carbon nanowires, carbon nanoballs, carbon nanohorns, carbon nanocages, carbon nanorings, carbon aerogels, graphene, stabilized carbon, activated carbon, or a combination of at least one of these, but is not limited thereto. The porous inorganic oxide may be, for example, at least one selected from the group consisting of zirconia, alumina, titania, silica, and ceria. The specific surface area of ​​the carrier is 50m 2 / g or more, and the average particle size can correspond to 10 to 300 nm (nanometers). If the specific surface area of ​​the support is less than the above range, it is not possible to obtain a uniform distribution of the metal nanoparticles.

[0033] The metal nanoparticles may be, for example, a platinum-based metal or a non-platinum-based metal. The platinum-based metal may be platinum (Pt) or a platinum-based alloy (Pt-M). M may be 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). Examples of the platinum-based alloy (Pt-M) that can be used include Pt-Pd, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ru, Pt-Ni, Pt-Co, Pt-Y, Pt-Ru-W, Pt-Ru-Ni, Pt-Ru-Mo, Pt-Ru-Rh-Ni, Pt-Ru-Sn-W, Pt-Ru-Ir-Ni, Pt-Co, Pt-Co-Mn, 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 mixtures of two or more of these. The non-platinum based metal may be one or more selected from the group consisting of palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), and a non-platinum based alloy, such as 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, Fe-N, Fe-P, Co-N, or a mixture of two or more thereof.

[0034] As a method for manufacturing a membrane-electrode assembly according to the present invention, a batch-type or roll-to-roll-type decal transfer method or direct coating method can be used to form a catalyst layer on at least one surface of a polymer electrolyte membrane.

[0035] A polymer electrolyte membrane according to another embodiment of the present invention may be a reinforced composite membrane in which a porous support is impregnated with an ion conductor. The ion conductor may include a second ionomer, which may be the same as or different from the first ionomer.

[0036] The porous support according to the present invention may be a fluorine-based support or a nanoweb support. Specifically, the fluorine-based support may be, for example, expanded polytetrafluoroethylene (e-PTFE) having a microstructure of polymer fibrils or a microstructure in which nodes are connected to each other by fibrils. Alternatively, a film having a microstructure of polymer fibrils without the nodes may be used as the porous support.

[0037] The fluorine-based support can include a perfluorinated polymer. The porous support can be made by extruding dispersion-polymerized PTFE into a tape in the presence of a lubricant and stretching the resulting material to produce a more porous and stronger porous support. The amorphous content of the PTFE can also be increased by heat-treating the e-PTFE at a temperature above the melting point of the PTFE (approximately 342°C). The e-PTFE film produced by this method can have micropores with various diameters and porosity. The e-PTFE film produced by this method can have at least 35% voids, and the diameter of the micropores can be approximately 0.01 to 1 μm (micrometer).

[0038] The nanoweb substrate according to one embodiment of the present invention may be a nonwoven fibrous web composed of randomly oriented fibers. The nonwoven fibrous web refers to a sheet having a structure of individual fibers or filaments that are interlaid but not in the same manner as a woven fabric. The nonwoven fibrous web may be manufactured by any method selected from the group consisting of carding, garnetting, air-laying, wet-laying, meltblowing, spunbonding, and stitchbonding. The fibers may include one or more polymeric materials, and any of those generally used as fiber-forming polymeric materials may be used, specifically hydrocarbon-based fiber-forming polymeric materials. For example, the fiber-forming polymeric material may include any one selected from the group consisting of polyolefins such as polybutylene, polypropylene, and polyethylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides (nylon-6 and nylon-6,6), polyurethanes, polybutene, polylactic acid, polyvinyl alcohol, polyphenylene sulfide, polysulfone, fluid crystalline polymers, polyethylene-co-vinyl acetate, polyacrylonitrile, cyclic polyolefins, polyoxymethylene, polyolefin-based thermoplastic elastomers, and combinations thereof, although the technical concept of the present invention is not limited thereto.

[0039] The nanoweb substrate according to an embodiment of the present invention may be a substrate in which nanofibers are accumulated in the form of a nonwoven fabric containing a large number of pores. The nanofibers are preferably made of a hydrocarbon-based polymer, which exhibits excellent chemical resistance, hydrophobicity, and is not susceptible to deformation due to moisture in a humid environment. Specifically, the hydrocarbon-based polymer may be selected from the group consisting of nylon, polyimide, polyaramid, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene butadiene rubber, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyvinylidene fluoride, polyvinyl butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamideimide, polyethylene terephthalate, polyphenylene sulfide, polyethylene, polypropylene, copolymers thereof, and mixtures thereof. Among these, polyimide is preferably used because of its excellent heat resistance, chemical resistance, and dimensional stability.

[0040] The nanoweb substrate is an aggregate of randomly arranged nanofibers produced by electrospinning. Taking into account the porosity and thickness of the nanoweb, the nanofibers preferably have an average diameter of 40 to 5,000 nm (nanometers), calculated from the average of 50 fiber diameters measured using a scanning electron microscope (JSM6700F, JEOL). If the average diameter of the nanofibers is below this range, the mechanical strength of the porous substrate may be reduced. If the average diameter of the nanofibers is above this range, the porosity may be significantly reduced and the thickness may be increased.

[0041] The thickness of the nonwoven fibrous web may be 10 to 50 μm (micrometers), specifically 15 to 43 μm (micrometers). If the thickness of the nonwoven fibrous web is less than the above range, the mechanical strength may decrease, and if it exceeds the above range, the resistance loss may increase, and the weight reduction and integration may decrease. The nonwoven fibrous web has a basic weight of 5 to 30 mg / cm. 2 If the basis weight of the nonwoven fibrous web is less than the above range, visible pores may be formed and the web may not function as a porous support, whereas if the basis weight is greater than the above range, the web may be manufactured in the form of paper or fabric with almost no pores.

[0042] The porous support according to the present invention preferably has a porosity of 30 to 90%, and more preferably 60 to 85%. If the porosity of the porous support is below this range, the impregnation of the ion conductor may be impaired, while if it exceeds this range, the morphology stability may be reduced, making subsequent processes difficult to perform. The porosity can be calculated as the ratio of the air volume within the porous support to the total volume of the porous support using the following equation (1): Here, the total volume is calculated by preparing a rectangular sample and measuring its width, length, and thickness, and the air volume can be obtained by measuring the mass of the sample and then subtracting the polymer volume, calculated from the density, from the total volume.

[0043]

number

[0044] 2.Fuel cell

[0045] Yet another embodiment of the present invention may provide a fuel cell including the membrane-electrode assembly.

[0046] FIG. 3 is a schematic diagram illustrating a fuel cell according to an embodiment of the present invention.

[0047] Referring to FIG. 3, a fuel cell 200 according to the present invention may include a fuel supply unit 210 for supplying a mixed fuel obtained by mixing fuel and water, a reforming unit 220 for reforming the mixed fuel to generate a reformed gas containing hydrogen gas, a stack 230 for generating electrical energy by electrochemically reacting the reformed gas containing hydrogen gas supplied from the reforming unit 220 with an oxidant, and an oxidant supply unit 240 for supplying an oxidant to the reforming unit 220 and the stack 230.

[0048] The stack 230 may include a plurality of unit cells that generate electrical energy by inducing an oxidation / reduction reaction between the reformed gas containing hydrogen gas supplied from the reforming unit 220 and the oxidant supplied from the oxidant supplying unit 240.

[0049] Each unit cell refers to a unit cell that generates electricity and includes the membrane-electrode assembly that oxidizes / reduces the reformed gas containing hydrogen gas and oxygen in an oxidant, and a separator plate (also called a bipolar plate, hereinafter referred to as "separator plate") that supplies the reformed gas containing hydrogen gas and the oxidant to the membrane-electrode assembly. The separator plates are disposed on both sides of the membrane-electrode assembly, with the membrane-electrode assembly at the center. In this case, the separator plates located at the outermost sides of the stack are sometimes referred to as end plates.

[0050] The end plate of the separation plate may be provided with a pipe-shaped first supply pipe 231 for injecting the reformed gas containing hydrogen gas supplied from the reforming section 220 and a pipe-shaped second supply pipe 232 for injecting oxygen gas, and the other end plate may be provided with a first exhaust pipe 233 for discharging the reformed gas containing hydrogen gas that ultimately remains unreacted in the plurality of unit cells to the outside and a second exhaust pipe 234 for discharging the oxidant that ultimately remains unreacted in the unit cells to the outside.

[0051] In the fuel cell, the separator, fuel supply section, and oxidant supply section that constitute the electricity generating section are the same as those used in ordinary fuel cells, and therefore detailed description thereof will be omitted in this specification.

[0052] Hereinafter, the embodiments of the present invention will be described in detail so that a person having ordinary skill in the art to which the present invention pertains can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited by the following content.

[0053] [Synthesis Example 1: Synthesis of plate-like mesoporous silica]

[0054] To synthesize the plate-shaped mesoporous silica used as a template, ZrOCl2·8H2O (0.32 g) and Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic P123; 2.0 g) were dissolved in 2.0 M HCl aqueous solution, followed by the addition of 4.2 g of TEOS (tetraethylorthosilicate) and hydrolysis at 35°C for 30 minutes. To the hydrolyzed mixture, 1.0 g of TMB (trimethylbenzene) was added, and hydrolysis and condensation polymerization were carried out at 35°C for 12 hours. The mixture was then hydrothermally treated at 90°C for 5 hours, filtered, dried, and calcined at 550°C for 6 hours to synthesize the plate-shaped mesoporous silica.

[0055] [Synthesis Example 2: Synthesis of non-plate-shaped mesoporous silica]

[0056] The conventional mesoporous silica used as the template was prepared by dissolving 2.0 g of Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic P123) in a 2.0 M aqueous HCl solution, adding 4.2 g of TEOS (tetraethylorthosilicate), and allowing hydrolysis and condensation polymerization to proceed at 35°C for 12 hours. The resulting material was then filtered, dried, and calcined at 550°C for 6 hours to synthesize non-platelet mesoporous silica.

[0057] [Production Example 1-1: Production of plate-shaped mesoporous carbon having aligned nanofibers]

[0058] Using 1.0 g of the plate-shaped mesoporous silica (length 600 nm, height 200 nm, mesopores 10 nm) prepared in Synthesis Example 1 as a template, 0.6 g of phenol formaldehyde resin (a polymer precursor) was filled into the mesopores, followed by polymerization at 140°C and carbonization in an inert gas atmosphere at 1,000°C. The template was then removed to produce plate-shaped mesoporous carbon with aligned nanofibers measuring 600 nm in length and 200 nm in height and mesopores of an average of 6 nm between the nanofibers.

[0059] [Preparation Example 1-2: Preparation of plate-shaped mesoporous carbon having aligned nanofibers coated on the surface and pores with an ionomer layer]

[0060] The plate-like mesoporous carbon prepared in Preparation Example 1-1 and perfluorosulfonic acid (PFSA) with an equivalent weight of 800 g / eq were placed in a container in a weight ratio of 0.8:1, and then mixed in a resonant acoustic mixer (RAM) at a gravitational acceleration of 60 G for 30 minutes to produce a solid mixture. The mixture was heat-treated at 130°C for 60 minutes to form an ionomer layer with a thickness of 3.0 nm on the surface and pores of the plate-like mesoporous carbon.

[0061] [Production Example 2-1: Production of plate-shaped mesoporous carbon having aligned nanotubes]

[0062] An acid-treated template was prepared by acid-treating 1.0 g of the plate-shaped mesoporous silica (length 600 nm, height 200 nm, mesopores 10 nm) prepared in Synthesis Example 1 using AlCl3. Using the acid-treated template, a plate-shaped mesoporous carbon was prepared in the same manner as in Preparation Example 1-1, ultimately containing aligned nanotubes with pores of 8 nm diameter and mesopores of 6 nm diameter between the nanotubes, measuring 600 nm in length and 200 nm in height.

[0063] [Production Example 2-2: Synthesis of plate-shaped mesoporous carbon having aligned nanotubes and an ionomer layer coated on the surface and pores]

[0064] An ionomer layer having a thickness of 3.0 nm was formed on the surface and in the pores of the plate-like mesoporous carbon in the same manner as in Production Example 1-2, except that the plate-like mesoporous carbon produced in Production Example 2-1 was used.

[0065] [Production Example 3: Production of non-plate-shaped mesoporous carbon]

[0066] Using 1.0 g of the conventional mesoporous silica (length 700 nm, height 700 nm, mesopores 7 nm) produced in Synthesis Example 2 as a template, a non-plate-shaped mesoporous carbon having an average mesopore size of 5 nm and a length of 700 nm and a height of 700 nm was produced in the same manner as in Production Example 1-1.

[0067] [Experimental Example 1: UHR-SEM photograph of plate-shaped mesoporous carbon according to Production Example 1-1]

[0068] FIG. 4 is an ultra high resolution (UHR)-SEM photograph of the plate-shaped mesoporous carbon having aligned nanofibers according to Preparation Example 1-1.

[0069] Referring to FIG. 4, a catalyst layer was formed using plate-shaped mesoporous carbon in Preparation Example 1-1, in which nanofibers were aligned and metal nanoparticles were not supported.

[0070] [Experimental Example 2: UHR-SEM photograph of plate-shaped mesoporous carbon from Production Example 2-1]

[0071] FIG. 5 is a UHR-SEM photograph of the plate-shaped mesoporous carbon having aligned nanotubes according to Preparation Example 2-1.

[0072] Referring to FIG. 5, a catalyst layer was formed using plate-shaped mesoporous carbon having aligned nanotubes and no metal nanoparticles supported thereon according to Preparation Example 2-1.

[0073] [Production Example 4: Production of membrane-electrode assembly]

[0074] <Example 1-1: Preparation of membrane-electrode assembly using unsupported plate-shaped mesoporous carbon according to Preparation Example 1-1>

[0075] (a) Step: Producing a polymer electrolyte membrane

[0076] A polymer electrolyte membrane was fabricated by the following steps: applying a polymer solution, which was a mixture of a solvent, in which water and isopropanol were mixed in a weight ratio of 1:1, and perfluorosulfonic acid, to a glass substrate using a doctor blade; gradually heating the applied polymer solution to 80°C and then drying it for 4 hours.

[0077] (b) Step: Forming a catalyst layer that is a single layer

[0078] 0.2 g of the metal nanoparticle-unloaded plate-shaped mesoporous carbon prepared in Synthesis Example 1-1, 1.0 g of a commercial Pt / C catalyst (Tanaka), and 1.3 g of a binder (EW=800) were mixed in a solvent using a high-shear mixer at 6,000 rpm for 40 minutes, and then subjected to two passes at 600 bar using a high-pressure disperser to prepare an electrode slurry. The electrode slurry was applied to both sides of the polymer electrolyte membrane using a slot die method and dried at 80°C for 5 minutes to form a single catalyst layer with a thickness of 10 μm.

[0079] <Example 1-2: Preparation of membrane-electrode assembly having plate-shaped mesoporous carbon with ionomer layer coated on unsupported surface and pores according to Preparation Example 1-2>

[0080] A membrane-electrode assembly was prepared in the same manner as in Example 1-1, except that 0.2 g of ionomer layer-coated mesoporous carbon plate prepared in Preparation Example 1-2 and 1.2 g of binder (EW=800) were used instead of the mesoporous carbon plate prepared in Preparation Example 1-1.

[0081] <Example 2-1: Preparation of membrane-electrode assembly using plate-shaped mesoporous carbon according to Preparation Example 2-1>

[0082] A membrane-electrode assembly was prepared in the same manner as in Example 1-1, except that the plate-shaped mesoporous carbon prepared in Preparation Example 2-1 was used instead of the plate-shaped mesoporous carbon prepared in Preparation Example 1-1.

[0083] <Example 2-2: Preparation of membrane-electrode assembly having plate-shaped mesoporous carbon with ionomer layer coated on unsupported surface and pores according to Preparation Example 2-2>

[0084] A membrane-electrode assembly was prepared in the same manner as in Example 1-2, except that the mesoporous carbon plate coated with an ionomer layer prepared in Preparation Example 2-2 was used instead of the mesoporous carbon plate coated with an ionomer layer prepared in Preparation Example 1-2.

[0085] <Comparative Example 1: Commercial Membrane-Electrode Assembly>

[0086] After preparing a polymer electrolyte membrane in the same manner as in Example 1-1, an electrode slurry containing 1.0 g of a commercial Pt / C catalyst (Tanaka) and 1.0 g of a binder (EW=800) was directly coated on both sides of the polymer electrolyte membrane to form a catalyst layer with a thickness of 8 μm.

[0087] <Comparative Example 2: Membrane-electrode assembly using non-plate-shaped mesoporous carbon>

[0088] A membrane-electrode assembly was prepared in the same manner as in Example 1-1, except that the normal mesoporous carbon prepared in Preparation Example 3 was used instead of the plate-shaped mesoporous carbon prepared in Preparation Example 1-1.

[0089] [Experimental Example 3: Cross-sectional SEM photograph of a membrane-electrode assembly containing plate-shaped mesoporous carbon according to Example 1-2]

[0090] FIG. 6 is a cross-sectional SEM photograph of a membrane-electrode assembly including plate-shaped mesoporous carbon having aligned nanofibers according to Example 1-2.

[0091] Referring to FIG. 6, a catalyst layer was formed using plate-shaped mesoporous carbon having aligned nanofibers according to Example 1-2.

[0092] [Experimental Example 4: Cross-sectional SEM photograph of a membrane-electrode assembly containing plate-shaped mesoporous carbon according to Example 2-2]

[0093] FIG. 7 is a cross-sectional SEM photograph of a membrane-electrode assembly including a plate-shaped mesoporous carbon layer having aligned nanotubes according to Example 2-2.

[0094] Referring to FIG. 7, a catalyst layer was formed using plate-shaped mesoporous carbon having aligned nanotubes according to Example 2-2.

[0095] [Experimental Example 5: Performance Evaluation]

[0096] 8 shows the performance evaluation results of the membrane-electrode assemblies manufactured in the examples and comparative examples under conditions of 80°C, 100% RH, and atmospheric pressure. Specifically, a fuel cell evaluation station was used to evaluate the performance of the membrane-electrode assemblies.

[0097] Referring to FIG. 8, the membrane-electrode assembly prepared according to the example showed improved performance compared to the comparative example.

[0098] [Experimental Example 6: Evaluation of catalyst durability in membrane-electrode assemblies]

[0099] The catalyst durability of the membrane-electrode assemblies according to the examples and comparative examples was evaluated according to the catalyst durability evaluation protocol of the U.S. Department of Energy (DOE). Specifically, the fuel cell evaluation station was used to evaluate the catalyst durability of the membrane-electrode assemblies.

[0100] Evaluation conditions: 80°C, H2 / N2 gas, anode 100 ccm / cathode 37.5 ccm flow rate, normal pressure, 0.6 to 1.0 V, 10,000 cycles at a speed of 50 mV / s, and then voltage loss was evaluated.

[0101] [Table 1]

[0102] Referring to Table 1, it can be seen that the voltage loss in the examples is significantly less than that in the comparative examples, and the durability of the catalyst is significantly improved.

[0103] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0104] 20: Catalyst layer IL: Ionomer layer

Claims

1. a polymer electrolyte membrane; a catalyst layer disposed on at least one surface of the polymer electrolyte membrane; The catalyst layer is The mesoporous carbon nanoparticles include unsupported platelet mesoporous carbon nanoparticles, The catalyst layer is a single layer. Membrane-electrode assembly.

2. The surface and pores of the plate-like mesoporous carbon are coated with an ionomer layer. The membrane-electrode assembly according to claim 1.

3. The ionomer layer is a first ionomer; The equivalent weight (EW) of the first ionomer is 600 to 1,200 g / eq. The membrane-electrode assembly according to claim 2.

4. The first ionomer is any one selected from the group consisting of a fluorine-based ionomer, a hydrocarbon-based ionomer, and a mixture thereof; The membrane-electrode assembly according to claim 3.

5. The plate-like mesoporous carbon is The nanofibers or nanotubes are aligned in the short axis direction. The membrane-electrode assembly according to claim 1.

6. The nanofibers and nanotubes each independently comprise: The height is 50 to 600 nm (nanometers); The membrane-electrode assembly according to claim 5.

7. A fuel cell comprising the membrane-electrode assembly according to any one of claims 1 to 6.

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