Fuel cell system

Abstract

The present invention provides a fuel cell system comprising a fuel cell stack, a hydrogen supply unit for supplying hydrogen to the stack, and an air supply unit for supplying air to the stack, wherein the air supply unit includes an air compressor and a humidifier, and a filter unit disposed between the air supply unit and the fuel cell stack and configured to remove peroxides and / or hydroxyl radicals.

Description

[Technical Field]

[0001] This invention relates to a novel fuel cell system. [Background technology]

[0002] A fuel cell is a type of power-generating battery that converts the chemical energy of hydrogen and oxygen into electrical energy through an electrochemical reaction. Unlike conventional chemical batteries such as dry cell batteries and storage batteries, fuel cells have the advantage of continuously producing electricity as long as hydrogen and oxygen are supplied, and are more than twice as efficient as internal combustion engines without heat loss. Furthermore, because it uses hydrogen and oxygen as raw materials and produces water as a by-product, it is an environmentally friendly energy generation device that does not contain pollutants. Therefore, fuel cells have the advantage of being environmentally friendly and reducing concerns about resource depletion due to increased energy consumption. Fuel cells can be classified into several types, including polymer electrolyte membrane fuel cells (PEMFCs), phosphate fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), and alkaline fuel cells (AFCs). Among these, polymer electrolyte fuel cells are known to be suitable for use in transportation systems because they can operate at lower temperatures and have a higher power density compared to other fuel cells. On the other hand, in polymer electrolyte fuel cells, water is generally formed when 2 moles of hydrogen and 1 mole of oxygen react in the fuel cell stack during operation. However, if the reaction proceeds incompletely, peroxides or hydroxide radicals may be generated as byproducts. When peroxides or hydroxide radicals generated in this way flow from the fuel cell stack into the humidifier, they induce oxidation of the organic hollow fiber membrane placed in the humidifier, leading to the decomposition and deterioration of the hollow fiber membrane. The decomposition and degradation of the hollow fiber membrane hinders the delivery of sufficiently moist air to the fuel cell stack, reducing the efficiency of the fuel cell stack and the fuel cell as a whole. Consequently, there remains an industry demand for technologies that prevent peroxides and hydroxide radicals generated from fuel cell stacks from being transferred into the humidifier. [Overview of the project] [Problems that the invention aims to solve]

[0003] To address the aforementioned problems, we provide a novel fuel cell system that prevents peroxides and hydroxide radicals generated from the fuel cell stack from flowing into the membrane humidifier. [Means for solving the problem]

[0004] In one aspect, a fuel cell system is provided, comprising: a fuel cell stack; a hydrogen supply unit for supplying hydrogen to the stack; and an air supply unit for supplying air to the stack, wherein the air supply unit includes an air compressor and a humidifier, and a filter unit disposed between the air supply unit and the fuel cell stack and configured to remove peroxides and / or radicals. In other aspects, a fuel cell system is provided, comprising a fuel cell stack, a hydrogen supply unit for supplying hydrogen to the stack, and an air supply unit for supplying air to the stack, wherein the air supply unit includes an air compressor and a humidifier, and a filter unit disposed inside the humidifier and configured to remove peroxides and / or radicals. In another aspect, a fuel cell system is provided, comprising a fuel cell stack, a hydrogen supply unit for supplying hydrogen to the stack, and an air supply unit for supplying air to the stack, wherein the air supply unit includes an air compressor and a humidifier, a first filter unit disposed between the air supply unit and the fuel cell stack and configured to remove peroxides and / or hydroxyl radicals, and a second filter unit disposed inside the humidifier and configured to remove peroxides and / or hydroxyl radicals. [Effects of the Invention]

[0005] A one-sided fuel cell system, by including a filter section positioned between the air supply unit and the fuel cell stack, or positioned inside the humidifier, and configured to remove peroxides and / or hydroxyl radicals, can prevent peroxides and / or hydroxyl radicals from entering the humidifier from the fuel cell stack, thereby preventing the decomposition and deterioration of the hollow fiber membrane inside the humidifier. [Brief explanation of the drawing]

[0006] [Figure 1] This is a block diagram showing the configuration of a fuel cell system according to one embodiment of the present invention. [Figure 2] This is a block diagram showing the configuration of a fuel cell system according to one embodiment of the present invention. [Figure 3] This is an exploded perspective view of a humidifier according to one embodiment of the present invention. [Figure 4] This is an exploded perspective view of a humidifier according to one embodiment of the present invention. [Modes for carrying out the invention]

[0007] The present inventive concept described below can be modified in various ways and may have many different embodiments. Specific embodiments are illustrated in the drawings and explained in detail in the detailed description. However, this is not intended to limit the present inventive concept to specific embodiments, but rather should be understood to include all modifications, equivalents, or substitutes that fall within the technical scope of the present inventive concept. The terms used herein are used solely to describe specific embodiments and are not intended to limit the scope of this invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. Hereafter, terms such as “includes” or “having” describe the presence of features, numbers, steps, operations, components, parts, ingredients, materials, or combinations thereof as described in the specification, and should not be understood to presuppose the presence or possibility of adding one or more other features, numbers, steps, operations, components, parts, ingredients, materials, or combinations thereof. When it is mentioned that one component is “connected” or “joined” with another component, it should be understood that the first component may be directly connected or joined to the other component, but that there may also be a new other component between the first component and the other component. On the other hand, when it is mentioned that one component is “directly connected” or “directly joined” with another component, it should be understood that there is no new other component between the first component and the other component. Throughout the specification, when a part such as a layer, film, region, or plate is said to be "on top of" or "above" another part, this includes not only when it is directly above another part, but also when there is yet another part in between. Throughout the specification, terms such as first, second, etc., are used to describe a variety of components, but components should not be limited by the term. Throughout the specification, the term "fluid communication" means that fluids, such as gases or liquids, are connected, coupled, or configured to communicate with each other, and the term is used solely for the purpose of distinguishing one component from another. The embodiments described below are merely exemplary, and various modifications are possible from such embodiments. A fuel cell system according to an embodiment of the present invention will be described below with reference to the block diagrams of FIGS. 1 and 2. FIGS. 1 and 2 schematically show the configuration of a fuel cell system according to an embodiment of the present invention in a block diagram. Referring to FIG. 1, a fuel cell system according to an embodiment of the present invention includes a fuel cell stack 1000, a hydrogen supply unit 2000, an air supply unit 3000, and a filter unit 4000. The fuel cell stack 1000 reacts hydrogen supplied from the hydrogen supply unit 2000 with oxygen supplied from the air supply unit 3000 to generate heat and steam. The fuel cell stack 1000 is composed of a membrane electrode assembly, an electrolyte membrane, a catalyst layer, electrodes of a cathode and an anode, a gas diffusion layer, a separator plate, and a gasket, etc. Each component can be manufactured by a known method using a known material. According to an embodiment, the membrane electrode assembly included in the fuel cell stack may include a porous support and an ion conductor layer disposed on the outer surface of the porous support. The porous support suppresses volume expansion due to moisture generated from the electrodes during the operation of the fuel cell to achieve dimensional stability, and may contain a large number of ion conductors due to its porous large surface area. The porous support includes a fluorine-based support or a hydrocarbon-based polymer, and may include, for example, nylon, polyimide (PI), polybenzoxazole (PBO), polybenzimidazole (PBI), polyamideimide (PAI), polyethylene terephthalate, polyethylene (PE), polytetrafluoroethylene (PTFE), polypropylene (PP), or a combination thereof.

[0008] The aforementioned ion conductor uses a polymer with high ion exchange capacity and can be easily selected and used by an ordinary engineer from known ion conductors. For example, fluoropolymers containing poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), copolymers of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid groups, defluorinated sulfurized polyether ketones 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 (sulfonated Polyketone, 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), sulfonated polyarylene ether nitrile, sulfonated polyarylene ether ether nitrile, polyarylene ether sulfone ketone, or a combination thereof.

[0009] According to one embodiment, the electrolyte membrane included in the fuel cell stack may include a fluororesin to ensure mechanical strength. The electrolyte membrane includes a fluorine-based porous resin. For example, it can be obtained by impregnating a support such as polytetrafluoroethylene (PTFE) with a fluorine-based ion conductor. According to one embodiment, the cathode and anode of the fuel cell stack are respectively disposed at the ends of the fuel cell stack. In the anode, hydrogen and oxygen are generated by water decomposition, and the cathode to which the hydrogen generated from the anode is transmitted generates hydrogen atoms by a reduction reaction. At this time, a catalyst layer may be further included as a raw material for lowering the activation energy of the reactions of the cathode and anode. The catalyst can be used without limitation as long as it is involved in the reaction of the battery and lowers the reaction activation energy. For example, a porous carbon-based carrier supported with a platinum-based metal or a metal having a catalytic function can be used. According to one embodiment, a gas diffusion layer may be further included to facilitate the diffusion of air flowing in from the humidifier. The gas diffusion layer can improve the efficiency of the fuel cell by increasing the contact frequency between the air flowing in from the humidifier and the membrane electrode assembly. In addition, it is understood that various elements constituting the fuel cell are appropriately selected and applied from known techniques by ordinary technicians. The fuel cell stack 1000 generates electricity through a hydrogen-oxygen bonding reaction. Specifically, hydrogen is supplied to the anode side and oxygen to the cathode side of the fuel cell stack 1000. On the anode side, hydrogen ions are generated by the oxidation reaction of hydrogen, and the electrons generated at this time move to the cathode side through the wire. The hydrogen ions move to the cathode side through the electrolyte membrane and come into contact with oxygen to form water vapor. Specifically, the reduction reaction of oxygen at the cathode electrode of the fuel cell stack forms hydrogen peroxide (H2O2) as an intermediate, which can generate hydrogen peroxide or hydroxide radicals from the decomposition of hydrogen peroxide at the cathode electrode. These hydrogen peroxide and hydroxide radicals can then be transferred together when humid air containing water vapor is transferred to the humidifier for reuse. As a result, a new problem arises: hydrogen peroxide and hydroxide radicals can penetrate into the humidifier, inducing oxidation of the hollow fiber membrane made from organic polymers, leading to deterioration of the hollow fiber membrane.

[0010] Accordingly, the inventors of the present invention have fabricated and placed a filter unit 4000 that collects and / or removes hydrogen peroxide and / or hydroxide radicals on the water vapor transfer path from the fuel cell stack to the humidifier or inside the humidifier, in order to block hydrogen peroxide and / or hydroxide radicals leaking from the fuel cell stack from entering the humidifier. A further explanation of this filter section will be provided later. The hydrogen supply unit 2000 supplies the stored hydrogen to the fuel cell stack 1000. Any hydrogen supply unit that supplies hydrogen to the fuel cell stack can be used without restriction. The air supply unit 3000 includes an air compression unit 3100 that compresses outside air to generate a first fluid and a humidifier 3200 that humidifies the first fluid and transmits it to the fuel cell stack. The air compressor 3100 and the humidifier 3200 are arranged to communicate with each other, and the humidifier 3200 may be positioned downstream of the air compressor so that outside air that has passed through the air compressor 3100 is supplied to the inside of the humidifier 3200. The air compression unit 3100 supplies a first fluid, which is compressed by receiving outside air, into the humidifier. The air compression unit 3100 is a device for compressing a fluid such as air, and may include, for example, a blower or a compressor. If necessary, an additional filter may be installed in front of the air compression unit inlet to block the entry of contaminants, or a separate air filter may be provided. The humidifier 3200 receives compressed air from the air compressor 3100, humidifies it, and then supplies it to the fuel cell stack.

[0011] The humidifier 3200 facilitates moisture exchange between outside air and steam generated from the fuel cell stack 1000, and supplies humidified air into the fuel cell stack 1000. Details regarding humidifier 3200 can be understood by referring to Figures 3 and 4. The humidifier 3200 may include a first inlet 121 through which a first fluid flows in from the air compression unit 3100, a first outlet 121 for transmitting the humidified air from the humidifier to the fuel cell stack, and a second inlet 112 through which a second fluid (i.e., high-temperature, high-humidity air) flows in from the fuel cell stack. The filter unit 4000 may be placed between the humidifier 3200 and the fuel cell stack 1000. In one embodiment, the filter unit 4000 may be positioned between the fuel cell stack 1000 and the second inlet 112 of the humidifier 3200. For example, it may be positioned adjacent to the second inlet 112 into which the second fluid flows from the fuel cell stack 1000, or adjacent to the steam outlet (not shown) of the fuel cell stack 1000. The filter portion 4000 may include a porous substrate and an antioxidant provided on the surface of the porous substrate. The porous substrate is a porous nonwoven fabric. For example, the porous substrate includes a film on its surface having an average pore size of 50 nm to 1000 μm. When the average pore size of the porous substrate satisfies 50 nm to 1000 μm, moisture can be selectively allowed to pass through, and oxidizing substances contained in the moisture can be removed by a chemical reaction upon contact with an antioxidant. For example, the average pore size of the porous substrate may be 500 nm to 900 μm, 1 μm to 800 μm, 10 μm to 700 μm, 100 μm to 600 μm, or 200 μm to 500 μm, and is not limited to these, but may have any numerical range included within the aforementioned range. The porous substrate may selectively include either a hydrophilic or hydrophobic film. For example, and without limitation, the porous substrate may include films containing thermoplastic polymers such as polyethylene, polypropylene, 1-octene, styrene, polyolefin(co)polymers, polyamides, poly-1-butene, poly-4-methyl-1-pentene, polyethersulfone, ethylenetetrafluoroethylene, polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyamide, cellulose acetate, cellulose nitrate, regenerated cellulose, polyvinyl chloride, polycarbonate, polyethylene terephthalate, polyimide, polytetrafluoroethylene, ethylenechlorotrifluoroethylene, or combinations thereof. The porous substrate may include all known substrates having a mesh-like structure. The antioxidant may be provided on one or both sides of the porous substrate. For example, the antioxidant may be provided on both sides of the porous substrate, but the concentration of the antioxidant provided on the first side facing the fuel cell stack 1000 is higher than the concentration of the antioxidant provided on the second side opposite the first side.

[0012] The aforementioned antioxidant may include organic antioxidants, metal antioxidants, organometallic antioxidants, HALS (Hindered amine Light stabilizer) type antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, or combinations thereof. For example, the organic antioxidant may include coumaric acid, dipamine, hydroquinone, phenolphthalein, phthalic acid, acetylsalicylic acid, phenolic antioxidants, niacin, luminol, urea, phytic acid, glyoxal, or any mixture thereof. For example, the metal-based antioxidant may include salts of Ce metal such as Ce(NO3)3, CECl3, and Ce2(SO4)3, salts of Mn metal such as Mn(NO3), metal oxides such as CeO2, CeSiO2, MnO2, and TiO2, or any mixture thereof. For example, the organometallic complex may include a Ce-crown complex, a Ce-phosphoric acid complex, Ce-bypyridine, or any mixture thereof. The filter section 4000 is a mesh filter manufactured by omitting the porous substrate and processing the antioxidant into wires, which are then arranged to form a mesh. In this case, the antioxidant wires are made primarily from a metal-based antioxidant, and, if necessary, can be further combined with other antioxidants such as organic antioxidants, organic-metallic antioxidants, HALS-based antioxidants, sulfur-based antioxidants, or phosphorus-based antioxidants. One method for processing antioxidants into wires involves dispersing an antioxidant, primarily a metal-based antioxidant, in a solvent, and then adding a wire-forming catalyst to form the antioxidant wire. However, the method is not limited to this, and antioxidant wires can be produced using known methods. The fabricated antioxidant wires can be arranged in a mesh pattern to create a mesh-like filter. This porous mesh-like filter can then be applied to the filter section 4000. The above-mentioned filter unit 4000 has different uses and operating mechanisms from the filtration filters conventionally used in humidifiers. Conventionally, in order to prevent contamination of the humidifier, a filter for filtering contaminants was installed at the fluid inlet of the humidifier. The filtration filter achieves physical filtration by adjusting the pore size of the filter to filter specific substances. On the other hand, the filter unit 4000 according to an embodiment of the present invention contains an antioxidant substance and has a function of removing such oxide substances through a chemical reaction with oxide substances such as peroxides or hydroxyl radicals. That is, the filter unit 4000 according to an embodiment of the present invention chemically removes desired substances with a filter, which is distinguished from a physical filtration membrane. Therefore, the filter unit 4000 according to an embodiment of the present invention must have a surface area within a certain range or more for effective removal of oxide substances and is not limited by the pore size required for physical filtration.

[0013] The filter unit 4000 according to an embodiment has a specific surface area of 40 cm 2 / g or more and 200 m 2 / g or less. The specific surface area was confirmed by measuring the nitrogen adsorption amount using a BET (Brunauer, Emmett, Teller) analyzer. When the specific surface area is less than 40 cm 2 / g, the oxide substances pass through without being sufficiently contacted by the filter unit 4000 and reach the hollow fiber membrane. When it is 200 m 2 / g or more, not only is it difficult to form the filter, but even if it is formed, the durability of the filter is significantly reduced and it is difficult to apply it to the filter unit. For example, the specific surface area of the filter unit 4000 is 40 cm 2 / g to 100 m 2 / g, 40 cm 2 / g to 50 m 2 / g, 40 cm 2 / g to 10 m 2 / g, 40 cm 2 / g to 1 m 2 / g, 40 cm 2 / g to 800 cm 2 / g, 40cm 2 / g or 600cm 2 / g, 40cm 2 / g or 400cm 2 / g, 40cm 2 / g or 200cm 2 / g, or 50cm 2 / g or 150cm 2 The range is / g, but it is not limited to these values ​​and can include any range within the aforementioned range. In one example, the filter section 4000 has a pore size of 50 nm to 5000 μm. If the pore size is excessively small, the passage of moisture is limited, making it difficult to achieve sufficient moisture exchange in the membrane humidifier. If the pore size is excessively large, there is a high possibility that oxidizing substances will pass through the filter section without coming into contact with the antioxidant. Therefore, appropriately adjusting the pore size and surface area of ​​the filter section is effective in removing oxidizing substances. Referring to Figure 2, another embodiment of the present invention, a fuel cell system, includes a fuel cell stack 1000, a hydrogen supply unit 2000, an air supply unit 3000, and a filter unit 4000. For configurations identical to those described in Figure 1, separate explanations are omitted, and only the differences are explained. Referring to Figure 2, in another embodiment of the present invention, the fuel cell system has the filter section 4000 located inside the humidifier 3200. According to one embodiment, the humidifier includes a hollow fiber membrane that is in fluid communication with the outside air and the steam to exchange moisture, and the filter section may be positioned within the humidifier between the hollow fiber membrane and the second inlet.

[0014] For example, a filter unit 4000 is positioned adjacent to the second inlet inside the humidifier 3200, which essentially blocks the entry of peroxides and hydroxide radicals into the humidifier. The filter section 4000 located inside the humidifier 3200 is, as described in relation to Figure 1, a porous nonwoven filter or a porous mesh filter formed of an antioxidant wire coated on a porous substrate. If the filter is a porous substrate coated with an antioxidant, the antioxidant is distributed on both sides of the porous substrate, and the concentration of the antioxidant on the surface adjacent to the second inlet 112 is higher than the concentration of the antioxidant on the surface adjacent to the hollow fiber membrane. This structure allows for more effective removal of hydrogen peroxide and / or hydroxide radicals contained in the steam entering the humidifier. Furthermore, the porous nonwoven filter can be placed inside the humidifier so as to surround the hollow fiber membrane bundle. This effectively prevents deterioration by oxidizing substances without reducing the moisture exchange capacity of the hollow fiber membrane. If the filter section 4000 is a porous filter formed of antioxidant wire, the porous filter can be placed inside the humidifier adjacent to the second inlet 112. In this case, the porous filter formed of antioxidant wire may be cut to match the shape of the port of the inlet 112 and then placed. Although separate drawings are not provided, as explained in Figure 1, the filter unit 4000 is placed between the fuel cell stack 1000 and the humidifier 3200. Simultaneously, as explained in Figure 2, the filter unit 4000 is placed inside the humidifier 3200, thereby providing a double barrier to the entry of peroxides and hydroxide radicals from the fuel cell stack 1000 into the humidifier 3200. As a result, the durability of the humidifier can be further improved. Figures 3 and 4 are perspective views showing a fuel cell humidifier 100 used in a fuel cell system according to one embodiment of the present invention. As shown in Figures 3 and 4, the fuel cell humidifier 100 of the present invention includes an intermediate case 110, a cap case 120, a fixing part 130, and a hollow fiber membrane bundle 200. A porous filter or nonwoven porous filter made of antioxidant wire is placed on the inner surface of the intermediate case 110. When such a filter is installed, oxidizing substances that enter the humidifier can be proactively captured and removed. The intermediate case 110 is combined with the cap case 120 to form the outer shape of the membrane humidifier 100. The intermediate case 110 and the cap case 120 are made of hard plastic such as polycarbonate or metal. The intermediate case 110 and the cap case 120 have a circular cross-sectional shape in the width direction, as shown in Figure 3, or a polygonal cross-sectional shape in the width direction, as shown in Figure 4. The polygon can be a rectangle, square, trapezoid, parallelogram, pentagon, hexagon, etc., and the corners of the polygon may be rounded. The circular shape may also be an ellipse.

[0015] The intermediate case 110 has a second fluid inlet 112 through which the second fluid is supplied and a second fluid outlet 113 through which the second fluid is discharged. The aforementioned filter unit 4000 may be installed at the second fluid inlet 112 and the second fluid outlet 113 from which the second fluid is discharged (not shown). In this case, oxidizing substances can be captured and removed from the hot and humid air containing oxidizing substances generated from the fuel cell stack and entering the second fluid inlet. Figures 3 and 4 illustrate an example in which multiple hollow fiber membranes 210 are arranged in the intermediate case 110 in the shape of a single hollow fiber membrane bundle 200. However, the hollow fiber membranes 210 may also be arranged in the intermediate case 110 in a state where they are divided and housed in two or more cartridges. The cartridge may be encased in a porous filter or nonwoven porous filter composed of antioxidant wires. This prevents contact between the hollow fiber membrane bundle contained within the cartridge and oxidizing substances, thereby effectively preventing the decomposition of the hollow fiber membrane. A fluid inlet / outlet 121 is formed in the cap case 120. One of the cap cases 120, which are connected to both ends of the intermediate case 110, has a fluid inlet / outlet 121 that serves as the first fluid inlet, and the other cap case 121 has a fluid inlet / outlet 121 that serves as the first fluid outlet. The first fluid that flows in through the fluid inlet / outlet 121 that functions as the first fluid inlet passes through the internal conduit [i.e., the lumens] of the hollow fiber membrane 210 housed inside the intermediate case 110, and then flows out to the fluid inlet / outlet 121 that functions as the first fluid outlet. The ends of the hollow fiber membranes 210 are potted to the fixing portions 130. The fixing portions 130 bind the hollow fiber membranes 210 together while filling the gaps between the hollow fiber membranes 210 and the gap between the hollow fiber membranes 210 and the intermediate case 110. As a result, each end of the intermediate case 110 is sealed by the fixing portions 130, and a flow path for the second fluid is formed inside. The material of the fixing portions 130 is known and will not be described in detail herein.

[0016] The hollow fiber membrane 210 is obtained by spinning a spinning solution, which is a mixture of a polymer, an additive, and a solvent, and then coagulating it. The polymer may be selected from among known polymers suitable for forming hollow fiber membranes, and may include, for example, polyvinylidene fluoride (PVDF) polymers, polysulfone polymers, sulfonated polysulfone, cellulose acetate, cellulose triacetate, polymethyl methacrylate, nafion, polystyrene (PS) polymers, polytetrafluoroethylene (PTFE) polymers, perfluorosulfonic acid (PFSA) polymers, polyphenylsulfone polymers, polyethersulfone (PES) polymers, polyacrylonitrile (PAN) polymers, polyetherimide (PEI) polymers, polyimide (PI) polymers, or any combination of the aforementioned polymers. For example, the polymer may include a polystyrene-based polymer. The hollow fiber membrane may further contain additives such as surfactants, hydrophilic organic compounds, or hydrophilic polymers. Such additives may be added in appropriate amounts, selected to the extent that they do not impair the inherent properties of the hollow fiber membrane. It would be obvious to any ordinary technician that other materials commonly used in the manufacture of hollow fiber membranes may also be used. The hollow fiber membrane may have antioxidants randomly or uniformly dispersed within the polymer. For example, by uniformly dispersing the antioxidant within the polymer, the hollow fiber membrane can achieve improved durability against peroxides and hydroxyl radicals without significantly inhibiting the porosity of the hollow fiber membrane. The hollow fiber membrane may have a cavity inside and may contain multiple pores that communicate with gas between the inner and outer surfaces. The hollow fiber membrane may have a concentration gradient in which the concentration of the antioxidant increases from the inner surface to the outer surface. The solvent used in the spinning solution may include at least one of the first solvent, the second solvent, and the third solvent. For example, the solvent is a mixed solvent containing two of the first, second, and third solvents.

[0017] The first solvent may include butanol, isobutanol, octanol, pentanol, isopentanol, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, polyoxyethylene octylphenyl ether, or combinations thereof, as a solvent that does not dissolve the polymer at room temperature (e.g., 23-25°C) but dissolves it at high temperatures (e.g., 80°C or higher). The second solvent may include water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof, as a solvent that does not dissolve the polymer. The third solvent may include N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, methyl ethyl ketone, tetrahydrofuran, tetramethylurea, or trimethyl phosphate as a solvent that dissolves the polymer even at room temperature. A typical technician may use a mixture of one or more of the first, second, and third solvents, taking into consideration the desired properties of the hollow fiber membrane and the characteristics of the polymer. According to one example, when the solvent is a mixed solvent of two or more solvents, the mixing ratio of the solvents is 1:9 to 9:1 by weight, but is not limited to this, and can be selected within an appropriate range by an ordinary technician considering the polymer and antioxidant content, the viscosity of the spinning solution, and the physical properties of the final hollow fiber membrane. In the following, an embodiment of the present invention will be described through examples and comparative examples, and there is no intention to limit the scope of the present invention to these examples. (Examples) Example 1 A filter coated with CeO2 was attached to the upper end of the port connecting the humidifier and the stack, and then installed between the humidifier and the stack. The filter used was made by spraying CeO2 10-50 nm particles onto a nonwoven fabric with an average pore size of 200 μm and then drying it. After fabricating the filter by attaching the nonwoven fabric to the housing, it was installed in the humidifier. The filter is installed at the connection point between the port from which high-temperature, high-humidity fluid flows out of the fuel cell stack and the port from which that fluid flows into the humidifier, and the shape of the filter is circular, corresponding to the cylindrical shape of the port. The specific surface area of ​​the filter is approximately 60 cm². 2 It is / g.

[0018] Example 2 As described in Example 1, the filter was prepared by surrounding the hollow fiber membrane bundle with the filter inside the case during the humidifier's construction, and then potting it so that the filter would be installed inside the humidifier. Example 3 A nonwoven fabric with an average pore size of 100 μm was sprayed with CeO2 10-50 nm particles and then dried to produce a filter. The resulting filter had a specific surface area of ​​120 cm². 2 The value was / g, and a humidifier was fabricated by attaching it in the manner described in Example 1. Comparative Example 1 A humidifier was fabricated using the same method as in Example 1, except that a filter was not installed. Evaluation Example 1: Evaluation of Filter Performance In each of the humidifiers in Examples 1 to 3 and Comparative Example 1, a 3% H2O2 solution containing 1 ppm FeSO4 was introduced at a rate of 10 cc per minute. After 100 hours, the humidifiers were disassembled, and the decrease in molecular weight of the humidifying film was calculated, as shown in Table 1 below. [Table 1] Percentage of molecular weight reduction = [(Molecular weight of initial humidified film - Molecular weight of humidified film after immersion) / Molecular weight of initial humidified film] × 100 As shown in Table 1 above, when a filter coated with CeO2 is installed inside the humidifier, it was confirmed that it prevents degradation and decomposition of peroxides and hydroxide radicals. Furthermore, it was confirmed that the effect is greater the larger the surface area on which the filter is installed. Therefore, by applying such a filter, the humidifying film can be effectively protected from peroxides and hydroxide radicals generated from the fuel cell stack.

Claims

1. Fuel cell stack and A hydrogen supply unit that supplies hydrogen to the aforementioned stack, An air supply unit that supplies air to the stack, the air supply unit includes an air compressor and a humidifier, A fuel cell system comprising a filter unit disposed between the air supply unit and the fuel cell stack and configured to remove peroxides and / or hydroxide radicals.

2. The fuel cell system according to claim 1, wherein the air compressor and the humidifier are arranged to communicate with each other, and the humidifier is positioned downstream of the air compressor so that the first fluid that has passed through the air compressor is supplied into the humidifier.

3. The fuel cell system according to claim 1, wherein the humidifier includes a first inlet into which a first fluid provided from an air compression unit flows, a first outlet for transmitting the air humidified by the humidifier to a fuel cell stack, and a second inlet into which a second fluid flows from the fuel cell stack.

4. The fuel cell system according to claim 3, wherein the filter section is disposed between the fuel cell stack and the second inlet of the humidifier.

5. The fuel cell system according to claim 1, wherein the filter portion comprises a porous substrate and an antioxidant provided on the surface of the porous substrate.

6. The fuel cell system according to claim 5, wherein the porous substrate is a porous nonwoven fabric.

7. The fuel cell system according to claim 5, wherein the porous substrate has pores with an average pore size of 50 nm to 1000 μm.

8. The filter section has a specific surface area of ​​40 cm². 2 / g or more 200m ２ The fuel cell system according to claim 5, wherein the amount is less than or equal to / g.

9. The fuel cell system according to claim 5, wherein the antioxidant is arranged on both sides of the porous substrate, and the concentration of the antioxidant on the side adjacent to the fuel cell stack is higher than the concentration of the antioxidant on the side adjacent to the air supply unit.

10. The fuel cell system according to claim 5, wherein the antioxidant includes an organic antioxidant, a metal antioxidant, an organometallic antioxidant, a HALS (Hindered amine Light stabilizer) type, a sulfur-based antioxidant, a phosphorus-based antioxidant, or a combination thereof.

11. Fuel cell stack and A hydrogen supply unit that supplies hydrogen to the aforementioned stack, An air supply unit that supplies air to the stack, the air supply unit includes an air compressor and a humidifier, A fuel cell system comprising: a filter unit disposed inside the humidifier and configured to remove peroxides and / or hydroxide radicals.

12. The fuel cell system according to claim 11, wherein the air compressor and the humidifier are arranged to communicate with each other, and the humidifier is positioned downstream of the air compressor so that the first fluid that has passed through the air compressor is supplied into the humidifier.

13. The fuel cell system according to claim 11, wherein the humidifier includes a first inlet through which a first fluid flows in from an air compression unit, a first outlet for transmitting the air humidified by the humidifier to a fuel cell stack, and a second inlet through which a second fluid flows in from the fuel cell stack.

14. The humidifier includes a hollow fiber membrane configured to be in fluid communication with the first fluid and the second fluid so as to exchange moisture between them. The fuel cell system according to claim 11, wherein the filter section is disposed within the humidifier between the hollow fiber membrane and the second inlet.

15. The fuel cell system according to claim 11, wherein the filter portion comprises a porous substrate and an antioxidant provided on the surface of the porous substrate.

16. The fuel cell system according to claim 15, wherein the porous substrate is a porous nonwoven fabric.

17. The fuel cell system according to claim 15, wherein the porous substrate has pores with an average pore size of 50 nm to 1000 μm.

18. The filter section has a specific surface area of ​​40 cm². 2 / g or more 200m ２ The fuel cell system according to claim 14, wherein the amount is less than or equal to / g.

19. The fuel cell system according to claim 15, wherein the antioxidant includes an organic antioxidant, a metal antioxidant, an organometallic antioxidant, a HALS (Hindered amine Light stabilizer) type, a sulfur-based antioxidant, a phosphorus-based antioxidant, or a combination thereof.

20. Fuel cell stack and A hydrogen supply unit that supplies hydrogen to the aforementioned stack, An air supply unit that supplies air to the stack, the air supply unit includes an air compressor and a humidifier, A first filter unit is disposed between the air supply unit and the fuel cell stack and is configured to remove peroxides and / or hydroxyl radicals. A fuel cell system comprising: a second filter unit disposed inside the humidifier and configured to remove peroxides and / or hydroxide radicals.

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