Membrane electrode assembly capable of satisfying both requirements for excellent performance and high durability, and fuel cell including the same

Abstract

To provide a membrane electrode assembly that can satisfy both requirements of excellent performance and high durability, and to provide a fuel cell including the same.SOLUTION: A membrane electrode assembly includes a first electrode, a second electrode, and an electrolyte membrane between the first and second electrodes. The first electrode includes a first segment with a first durability, and a second segment with a second durability different from the first durability.SELECTED DRAWING: Figure 1

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 that can satisfy both requirements of excellent performance and high durability, and a fuel cell including the same. [Background technology]

[0002] Polymer Electrolyte Membrane Fuel Cells (PEMFCs), which generate electricity using a stacked structure of unit cells consisting of a membrane-electrode assembly (MEA) and a separator (called a bipolar plate), are drawing attention as a next-generation energy source that can replace fossil energy due to their high energy efficiency and environmentally friendly characteristics. The membrane electrode assembly generally includes an anode (also called a fuel electrode), a cathode (also called a cathode), and a polymer electrolyte membrane (PEM) therebetween.

[0003] When fuel such as hydrogen gas is supplied to the anode, hydrogen ions (H+) and electrons (e-) are generated by the oxidation reaction of hydrogen at the anode. The generated hydrogen ions are transferred to the cathode via a polymer electrolyte membrane (PEM), and the generated electrons are transferred to the cathode via an external circuit. Oxygen in the air supplied to the cathode combines with the hydrogen ions and the electrons and is reduced to generate water. In general, the performance and durability of a membrane electrode assembly are closely related to the performance and durability of the electrodes. However, the trade-off between the performance and durability of electrodes such as anodes / cathodes forces the sacrifice of one of the performance and durability of the electrodes. That is, an oxidation / reduction catalyst with high catalytic activity tends to have unsatisfactory durability. On the other hand, an oxidation / reduction catalyst with high durability tends to have unsatisfactory performance.

[0004] As a result, it is believed by those of ordinary skill in the fuel cell art that it is not possible to fabricate a membrane electrode assembly and / or fuel cell that simultaneously meets both the requirements for excellent performance and high durability. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the present invention relates to a membrane electrode assembly and a fuel cell including the same, which can avoid problems caused by the limitations and shortcomings of the related art. One aspect of the present invention is to provide a membrane electrode assembly that can meet both requirements of excellent performance and high durability. Another aspect of the present invention is to provide a fuel cell that can meet both requirements of excellent performance and high durability. In addition to the above-mentioned aspects of the present invention, other features and advantages of the present invention will be described below and will be apparent to those skilled in the art from such description. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a membrane electrode assembly including a first electrode, a second electrode, and an electrolyte membrane between the first and second electrodes, wherein the first electrode includes a first segment having a first durability and a second segment having a second durability different from the first durability. The first segment may include a first catalyst and the second segment may include a second catalyst, and the first and second catalysts may differ from each other in terms of durability. The first catalyst may include a first support and first metal particles dispersed on the first support, and the second catalyst may include a second support and second metal particles dispersed on the second support, and the first and second supports may be different from each other. The first durability may be higher than the second durability, the first support may be a crystalline carbon-based support or a conductive inorganic oxide support, and the second support may be a non-crystalline carbon-based support.

[0007] The first support may include graphitized carbon black, carbon nanotubes, carbon nanofibers, SnO2, TiO2, or a mixture of two or more of these, and the second support may include non-graphitic carbon black. The first and second segments may be arranged side by side in a direction parallel to a surface of the electrolyte membrane. The first durability may be higher than the second durability, and the first segment may occupy less than or equal to 50% of a total active area of ​​the first electrode.

[0008] The first durability may be higher than the second durability, the first catalyst may include a first support and first metal particles dispersed on the first support, the second catalyst may include a second support and second metal particles dispersed on the second support, and a weight per unit area of ​​the first metal particles in the first segment may be higher than a weight per unit area of ​​the second metal particles in the second segment. The first durability can be higher than the second durability, the first segment can further comprise a first ionomer, the second segment can further comprise a second ionomer, and a side chain length of the first ionomer can be shorter than a side chain length of the second ionomer.

[0009] The first durability may be higher than the second durability, the first catalyst may include a first support and first metal particles dispersed on the first support, the second catalyst may include a second support and second metal particles dispersed on the second support, and a loading rate of the first metal particles on the first support may be lower than a loading rate of the second metal particles on the second support. The first durability may be higher than the second durability, the first segment may have a double layer structure of first and second sub-layers sequentially formed over the electrolyte membrane, the second segment may have a single layer structure, one of the first and second sub-layers may include a first catalyst, and the other of the first and second sub-layers and the second segment may each include a second catalyst different from the first catalyst.

[0010] The first catalyst may include a first support and first metal particles dispersed on the first support, and the second catalyst may include a second support and second metal particles dispersed on the second support, the first support may be a crystalline carbon-based support or a conductive inorganic oxide support, and the second support may be a non-crystalline carbon-based support. The first electrode may be an anode where a hydrogen oxidation reaction occurs, the second electrode may be a cathode where an oxygen reduction reaction occurs, the first catalyst may be an oxygen evolution reaction (OER) catalyst, and the second catalyst may be a hydrogen oxidation reaction (HOR) catalyst. The first electrode may be an anode where a hydrogen oxidation reaction occurs, the first durability may be higher than the second durability, the first segment may include an OER catalyst and a first HOR catalyst, the second segment may include the second HOR catalyst, and the first and second HOR catalysts may be the same or different from each other.

[0011] The first electrode may be a cathode where an oxygen reduction reaction occurs, and the second electrode may be an anode where a hydrogen oxidation reaction occurs, the first durability may be higher than the second durability, and the first segment may have a higher porosity than the second segment. According to another aspect of the present invention, there is provided a fuel cell comprising a first separator, a second separator, and the membrane electrode assembly of claim 1 between the first and second separators, the first electrode being disposed between the first separator and the electrolyte membrane, the first separator comprising a first inlet for a first gas supplied to the first electrode, a first outlet for the first gas, and a first flow channel between the first inlet and the first outlet, the first durability being higher than the second durability, and the first segment being a segment corresponding to the first inlet or the first outlet.

[0012] The electrolyte membrane may have an active area and a non-active area surrounding the active area, the first electrode may be disposed on a first side of the active area and the second electrode may be disposed on a second side of the active area, and the fuel cell may further include a first subgasket disposed on the first side of the non-active area and surrounding the first electrode, a second subgasket disposed on the second side of the non-active area and surrounding the second electrode, a first gas diffusion layer between the first electrode and the first separator, and a second gas diffusion layer between the second electrode and the second separator. The fuel cell may further include a first gasket disposed between the first subgasket and the first separator and surrounding the first gas diffusion layer, and a second gasket disposed between the second subgasket and the second separator and surrounding the second gas diffusion layer. The above general description of the invention is intended to be illustrative or explanatory only and is not intended to limit the scope of the invention. Effect of the Invention

[0013] According to the present invention, it is possible to provide a membrane electrode assembly which simultaneously satisfies both the requirements of excellent performance and high durability. Therefore, the fuel cell of the present invention including such a membrane electrode assembly can have a sufficiently long life while exhibiting excellent performance. [Brief description of the drawings]

[0014] The accompanying drawings are intended to aid in the understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Figure 1] 1(a) and 1(b) are a plan view and a cross-sectional view of a membrane electrode assembly according to an embodiment of the present invention. [Diagram 2] 4(a) and (b) are a plan view and a cross-sectional view of a membrane electrode assembly according to another embodiment of the present invention. [Diagram 3] 1 is a cross-sectional view of a fuel cell according to an embodiment of the present invention. [Figure 4] FIG. 2 illustrates a flow channel of a separator according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments described below are presented for illustrative purposes only to help a clear understanding of the present invention, and are not intended to limit the scope of the present invention. 1(a) and (b) are plan and cross-sectional views of a membrane electrode assembly 1100 according to one embodiment of the present invention. As shown in FIG. 1, a membrane electrode assembly 1100 of the present invention includes a first electrode 1110, a second electrode 1120, and an electrolyte membrane 1130 between the first and second electrodes 1110,1120.

[0016] For example, the electrolyte membrane 1130 may be (i) a single membrane type polymer electrolyte membrane formed from an ionomer, or (ii) a reinforced composite membrane type polymer electrolyte membrane including a porous support impregnated with an ionomer. In both types of electrolyte membranes 1130, the ionomer can be a fluorine-based ionomer or a hydrocarbon-based ionomer and can have one or more ion-conducting groups selected from the group consisting of sulfonic acid groups, carboxyl groups, boronic acid groups, phosphate groups, imide groups, sulfonimide groups, sulfonamide groups, and sulfonyl fluoride groups. For example, the ionomer can be a fluorine-based ionomer such as poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), and the like.

[0017] Alternatively, the ionomer may be 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 polyphenylene oxide, 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 nitrile, sulfonated polyarylene ether etherThe polymer may be a hydrocarbon based ionomer such as polyarylene ether sulfone ketone, polyarylene ether sulfone ketone, or the like.

[0018] Porous supports that can be used for the reinforced composite membrane type electrolyte membrane 1130 are made of polytetrafluoroethylene (PTFE) or tetrafluoroethylene and CF2=CFC. n F 2n+1 (n is a real number from 1 to 5) or CF2 = CFO-(CF2CF(CF3)O) m C n F 2n+1 (m is a real number of 0 to 15, and n is a real number of 1 to 15). For example, an e-PTFE porous support in the form of an expanded film can be formed by extruding PTFE onto a tape in the presence of a lubricant, followed by an expansion process and a heat treatment process. An additional expansion process and a heat treatment process can be further performed after the heat treatment process. By controlling the expansion and heat treatment processes, e-PTFE porous supports with various microstructures can be formed. For example, the e-PTFE porous support can have a microstructure in which nodes are connected to each other by fibrils, or a microstructure consisting of only fibrils.

[0019] Alternatively, the porous support may be a nonwoven web. The nonwoven web may be formed from a support-forming liquid containing one or more hydrocarbon-based polymers selected from the group consisting of polyolefins (e.g., polyethylene, polypropylene, polybutylene, etc.), polyesters (e.g., PET, PBT, etc.), polyamides (e.g., nylon-6, nylon-6,6, aramid, etc.), polyamic acids (formed from a web and then converted to polyimides by an imidization process), polyurethanes, polybutenes, polylactic acids, polyvinyl alcohols, polyphenylene sulfide (PPS), polysulfones, fluid crystalline polymers, polyethylene-co-vinyl acetate, polyacrylonitrile, cyclic polyolefins, polyoxymethylene, and polyolefin-based thermoplastic elastomers. The nonwoven fibrous web may be produced by a method selected from the group consisting of wet-laying, electrospinning, carding, garnetting, air-laying, melt blowing, spunbonding, and stitch bonding.

[0020] Each of the first and second electrodes 1110, 1120 may be formed on a first surface and an opposite second surface of the electrolyte membrane 1130, respectively, by a decal transfer method or a direct coating method using an electrode slurry containing a catalyst, an ionomer, and a dispersion medium. In an effort to increase the active surface area of ​​a catalyst, catalysts in which metal particles are dispersed on an electrically conductive support are commonly used. The support can be (i) a carbon-based support, (ii) a conductive inorganic oxide support such as tin oxide, titania, zirconia, alumina, silica, and ceria, or (iii) a zeolite support. The carbon-based support may be a crystalline carbon-based support or a non-crystalline carbon-based support.

[0021] Specifically, the carbon-based support may be graphitized or non-graphitic carbon black, activated carbon, stabilized carbon, carbon spheres, carbon fibers, carbon sheets, carbon ribbons, fullerenes, carbon nanotubes (CNTs), carbon nanofibers, carbon nanowires, carbon nanoballs, carbon nanohorns, carbon nanocages, carbon nanorings, carbon aerogels, graphene, ordered porous carbons, mesoporous carbons, nanoporous carbons, or combinations of two or more of these.

[0022] In the present specification, the graphitized or non-graphitic carbon black is a concept that includes all of graphitized or non-graphitic Ketjen black, graphitized or non-graphitic Denka black, graphitized or non-graphitic acetylene black, etc. Graphitized carbon black, carbon nanotubes, carbon nanofibers, etc. can be classified as crystalline carbon-based supports, while non-graphitic carbon black can be classified as amorphous carbon-based supports.

[0023] The metal particles can be platinum (Pt) particles or platinum-based alloy particles. The platinum-based alloy can be Pt-Co, Pt-Cr, Pt-Fe, Pt-Mn, Pt-Mo, Pt-Ni, Pt-Pd, Pt-Ru, Pt-Sn, Pt-W, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-Co-Mn, Pt-Co-Ni, Pt-Co-P, Pt-Co-S, Pt-Cr-Ir, Pt-Fe-Ir, Pt-Fe-P, Pt-Fe-S, Pt-Ni-Ir, Pt-Ru-Ir, Pt-Ru-Mo, Pt-Ru-Ni, Pt-Ru-W, Pt-Ru-Ir-Ni, Pt-Ru-Rh-Ni, or Pt-Ru-Sn-W. The ionomer dispersed in the dispersion medium together with the catalyst is for hydrogen ion transport, and also functions as a binder for improving the adhesive strength between the first and second electrodes 1110 and 1120 and the electrolyte membrane 1130 . The above-mentioned ionomers that can be used to form the electrolyte membrane 1130 can also be used to form the first and second electrodes 1110, 1120. It is preferable that the ionomer of the electrolyte membrane 1130 and the ionomer of the first and second electrodes 1110, 1120 are the same type of ionomer, but the present invention is not limited thereto, and different types of ionomers can also be used to manufacture the electrolyte membrane 1130 and the first and second electrodes 1110, 1120, respectively.

[0024] The dispersion medium of the electrode slurry may be, but is not limited to, ethanol, distilled water, isopropyl alcohol, normal propyl alcohol, butanol, or a mixture of two or more of these. According to the present invention, as shown in FIG. 1, the first electrode 1110 includes a first segment 1111 having a first durability and a second segment 1112 having a second durability different from the first durability. In general, deterioration of the first electrode 1110 due to long-term operation of a fuel cell occurs mainly in a specific portion (etc.) (e.g., a portion corresponding to a gas inlet / outlet, hereinafter referred to as a "deterioration vulnerable portion") rather than occurring over the entire area of ​​the first electrode 1110. Therefore, by forming the first electrode 1110 so that the deterioration vulnerable portion (e.g., the first segment 1111) has higher durability than the remaining portions, it is possible to improve the durability of the entire membrane electrode assembly 1100 without sacrificing the performance of the remaining portions (e.g., the second segment 1112).

[0025] The first and second segments 1111 and 1112 may be arranged side by side in a direction parallel to a surface of the electrolyte membrane 1130 . Similar to the first electrode 1110, the second electrode 1120 may include segments 1121 and 1122 having different durability. For example, the second electrode 1120 may include a segment 1121 formed from the same material as a first segment 1111 of the first electrode 1110, and a segment 1122 formed from the same material as a second segment 1112 of the first electrode 1110. According to one embodiment of the present invention, the first and second segments 1111 and 1112 of the first electrode 1110 may have different durability by including different catalysts. That is, the first segment 1111 includes a first catalyst and the second segment 1112 includes a second catalyst, and the first and second catalysts may be different from each other in terms of durability.

[0026] One of the first and second catalysts (e.g., the first catalyst) is a catalyst that is relatively inferior in terms of performance but has relatively high durability and is used to form the deterioration-vulnerable portion of the first electrode 1110 (e.g., the first segment 1111), while the other (e.g., the second catalyst) is a catalyst that is relatively inferior in terms of durability but has relatively high performance and is used to form the remaining portion of the first electrode 1110 (e.g., the second segment 1112). In this manner, forming the deterioration vulnerable portion and the remaining portion of the first electrode 1110 with catalysts of different types having different durability is far more advantageous in achieving the objectives and effects of the present invention (i.e., providing a membrane electrode assembly that simultaneously meets the two requirements of excellent performance and high durability) than inducing a difference in durability between the deterioration vulnerable portion and the remaining portion using other factors (e.g., differences in catalyst concentration / coating amount / loading amount, differences in ionomer concentration, etc.).

[0027] As mentioned above, as part of an effort to increase the active surface area of ​​a catalyst, a catalyst in which metal particles are dispersed on an electrically conductive support is commonly used. In other words, the first catalyst may include a first support and first metal particles dispersed on the first support, and the second catalyst may include a second support and second metal particles dispersed on the second support. Therefore, according to one embodiment of the present invention, since the first and second catalysts themselves have different durability, the first and second supports themselves may be different from each other, and the first and second metal particles themselves may be different from each other. For example, by using a crystalline carbon-based support (e.g., graphitized carbon black, carbon nanotubes, carbon nanofibers, etc.) or a conductive inorganic oxide support (e.g., a support including SnO2, TiO2, or a mixture thereof) as the first support and using a non-crystalline carbon-based support (e.g., non-graphitic carbon black, etc.) as the second support, the first catalyst may have better durability than the second catalyst, and thus the first durability of the first segment 1111 may be higher than the second durability of the second segment 1112. In this case, the same type of metal particles may be used as the first and second metal particles, or the first metal particles may have higher durability than the second metal particles.

[0028] The first segment 1111, which has relatively high durability, may be a portion of the first electrode 1110 that is vulnerable to deterioration (e.g., a portion corresponding to the gas inlet and gas outlet of the separator described below), and may occupy less than 50% of the total active area of ​​the first electrode 1110. Furthermore, according to one embodiment of the present invention, not only are the first and second catalysts themselves different from each other in terms of durability, but the weight per unit area of ​​the first metal particles in the first segment 1111 and the weight per unit area of ​​the second metal particles in the second segment 1112 may also be different from each other. For example, the first catalyst has better durability than the second catalyst, and the weight per unit area of ​​the first metal particles in the first segment 1111 is greater than the weight per unit area of ​​the second metal particles in the second segment 1112, such that the first durability of the first segment 1111 is greater than the second durability of the second segment 1112. Here, the first and second metal particles may be the same.

[0029] Alternatively, not only may the first and second catalysts themselves differ from each other in terms of durability, but the first ionomer in the first segment 1111 and the second ionomer in the second segment 1112 may also differ from each other in terms of durability. In general, the durability of an ionomer is closely related to the length of its side chain. It has been shown that the shorter the side chain length, the smaller the performance reduction rate in an accelerated life evaluation of a fuel cell. In other words, it is believed that the shorter the side chain length of the ionomer, the higher the durability. Therefore, according to this embodiment, the side chain length of the first ionomer and the side chain length of the second ionomer may be different from each other. For example, because the first catalyst has better durability than the second catalyst and the side chain length of the first ionomer in the first segment is shorter than the side chain length of the second ionomer in the second segment, a first durability of the first segment 1111 can be higher than a second durability of the second segment 1112. Also, optionally, a weight per unit area of ​​the first metal particles in the first segment 1111 can be greater than a weight per unit area of ​​the second metal particles in the second segment 1112.

[0030] Alternatively, the first and second catalysts themselves may differ from each other in terms of durability, and the loading rate of the first metal particles on the first support and the loading rate of the second metal particles on the second support may differ from each other, where the first and second metal particles may be the same. Generally, the higher the loading rate of metal particles on the support, the higher the risk of dissolution and / or aggregation of metal particles due to corrosion of the support. Therefore, according to the alternative embodiment of the present invention, since the first catalyst has a better durability than the second catalyst and the loading rate of the first metal particles on the first support is lower than the loading rate of the second metal particles on the second support, the first durability of the first segment 1111 may be higher than the second durability of the second segment 1112. Optionally, the weight per unit area of ​​the first metal particles in the first segment 1111 may be greater than the weight per unit area of ​​the second metal particles in the second segment 1112.

[0031] Alternatively, the first electrode 1110 may be an anode where a hydrogen oxidation reaction occurs, the first segment 1111 includes an oxygen evolution reaction (OER) catalyst (hereinafter, 'OER catalyst') and a first hydrogen oxidation reaction (HOR) catalyst (hereinafter, 'first HOR catalyst'), and the second segment 1112 includes a second hydrogen oxidation reaction catalyst (hereinafter, 'second HOR catalyst'), so that a first durability of the first segment 1111 may be higher than a second durability of the second segment 1112. The first and second HOR catalysts may be the same or different from each other. Each of the first and second HOR catalysts is a platinum (Pt) particle or a platinum-based alloy particle (i.e., Pt-Co, Pt-Cr, Pt-Fe, Pt-Mn, Pt-Mo, Pt-Ni, Pt-Pd, Pt-Ru, Pt-Sn, Pt-W, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-C Pt-Ru-Ir, Pt-Ru-Mo, Pt-Ru-Ni, Pt-Ru-W, Pt-Ru-Ir-Ni, Pt-Ru-Rh-Ni, or Pt-Ru-Sn-W).

[0032] In general, reactions occurring at the anode to which hydrogen gas is supplied include (i) a hydrogen oxidation reaction performed by the HOR catalyst during normal supply of hydrogen gas, and (ii) a carbon oxidation reaction that occurs when the supply of hydrogen gas is reduced or interrupted due to reasons such as fuel shortage. The carbon oxidation reaction corrodes the carbon-based support of the HOR catalyst, causing dissolution and / or aggregation of metal particles of the HOR catalyst. The OER catalyst is a catalyst that can suppress the carbon oxidation reaction by inducing an oxygen generation reaction, and includes a support and metal particles dispersed thereon. The support of the OER catalyst can be the above-mentioned carbon-based support, conductive inorganic oxide support, or zeolite support, and the metal particles of the OER catalyst can be IrO2, RuO2, Ir x Sn 1-x O2 (x is a real number greater than 0 and less than 1), PtIr, IrRu, PtRuIr, or a mixture of two or more of these. 2(a) and (b) are plan and cross-sectional views of a membrane electrode assembly 1100 according to another embodiment of the present invention.

[0033] As shown in FIG. 2, according to another embodiment of the present invention, the first segment 1111 has a double layer structure of first and second sub-layers 1111a and 1111b sequentially formed on the electrolyte membrane 1130, and the second segment 1112 has a single layer structure. One of the first and second sub-layers 1111a, 1111b contains a first catalyst, and the other of the first and second sub-layers 1111a, 1111b and the second segment 1112 each contain a second catalyst different from the first catalyst, such that a first durability of the first segment 1111 can be higher than a second durability of the second segment 1112.

[0034] For example, as described above, a crystalline carbon-based support (e.g., graphitized carbon black, carbon nanotubes, carbon nanofibers, etc.) or a conductive inorganic oxide support (e.g., a support including SnO2, TiO2, or a mixture thereof, etc.) is used as the first support of the first catalyst, and a non-crystalline carbon-based support (e.g., non-graphitic carbon black) is used as the second support of the second catalyst, so that the first catalyst can have better durability than the second catalyst. In this case, the same type of metal particles are used as the first and second metal particles, or the first metal particles can have higher durability than the second metal particles. Alternatively, when the first electrode 1110 is an anode where a hydrogen oxidation reaction occurs and the second electrode 1120 is a cathode where an oxygen reduction reaction occurs, the above-mentioned OER catalyst is used for the first catalyst and the above-mentioned HOR catalyst is used for the second catalyst, so that the first durability of the first segment 1111 can be higher than the second durability of the second segment 1112.

[0035] According to yet another embodiment of the present invention, the first electrode 1110 is a cathode where an oxygen reduction reaction occurs, and the second electrode 1120 is an anode where a hydrogen oxidation reaction occurs, and the first segment 1111 has a higher porosity than the second segment 1112, so that water generated by the oxygen reduction reaction can be more efficiently discharged from the first segment 1111 than from the second segment 1112. Therefore, the first segment 1111, from which water that induces and / or accelerates electrode deterioration is relatively efficiently discharged, has a higher durability than the second segment 1112. As described above, the second electrode 1120 may also include segments 1121, 1122 formed to have the same material and structure as the exemplary first and second segments 1111, 1112 of the first electrode 1110. That is, the description of the first and second segments 1111, 1112 of the first electrode 1110 is equally applicable to the segments 1121, 1122 of the second electrode 1120.

[0036] The fuel cell 1000 of the present invention will be described in detail below with reference to FIGS. FIG. 3 is a cross-sectional view of a fuel cell 1000 according to one embodiment of the invention, and FIG. 4 is a diagram showing a flow channel 1211 of a first separator 1210 according to one embodiment of the invention. As shown in FIG. 3, the fuel cell 1000 of the present invention includes a first separator 1210, a second separator 1220, and the above-described membrane electrode assembly 1100 between the first and second separators 1210,1220. The first electrode 1110 of the membrane electrode assembly 1100 is disposed between the first separator 1210 and the electrolyte membrane 1130. Similarly, the second electrode 1120 of the membrane electrode assembly 1100 is disposed between the second separator 1220 and the electrolyte membrane 1130.

[0037] As shown in FIG. 4, the first separator 1210 includes a first inlet GI for a first gas supplied to the first electrode 1110, a first outlet GO for the first gas, and a first flow channel 1211 between the first inlet GI and the first outlet GO. According to the present invention, the first segment 1111 has a higher durability than the second segment 1112 (i.e., the first durability is higher than the second durability), and the first segment 1111 is a segment corresponding to the first inlet GI and / or the first outlet GO. Therefore, according to the present invention, by selectively forming only the deterioration vulnerable portion (etc.) of the first electrode 1110, which corresponds to the first inlet GI and / or the first outlet GO of the first separator 1210, to have high durability (i.e., by forming the first segment 1111 to have higher durability than the second segment 1112), it is possible to provide a fuel cell 1000 that can meet both the requirements of excellent performance and high durability.

[0038] Similarly, the second separator 1220 also includes a second inlet (not shown) for a second gas supplied to the second electrode 1120, a second outlet (not shown) for the second gas, and a second flow channel 1221 between the second inlet and the second outlet. In addition, the segment 1221 of the second electrode 1120 corresponding to the second inlet and / or the second outlet of the second separator 1220 may be formed to have higher durability than the other segments 1222. 3, the first and second electrodes 1110, 1120 are aligned with each other with the electrolyte membrane 1130 in between, and the electrolyte membrane 1130 has an active region that transfers hydrogen ions between the first and second electrodes 1110, 1120 and a non-active region surrounding the active region. That is, the first electrode 1110 is disposed on a first surface of the active region of the electrolyte membrane 1130, and the second electrode 1120 is disposed on a second surface of the active region of the electrolyte membrane 1130.

[0039] As shown in FIG. 3, a fuel cell 1000 according to one embodiment of the present invention includes a first subgasket 1310 disposed on a first side of the non-active area of ​​the electrolyte membrane 1130, and a second subgasket 1320 disposed on a second side of the non-active area of ​​the electrolyte membrane 1130. The first and second subgaskets 1310, 1320 (i) prevent the edges of the electrolyte membrane 1130 from being damaged due to repeated swelling and contraction during operation of the fuel cell 1000, (ii) improve the problem of poor handling of the membrane electrode assembly 1100 due to the electrolyte membrane 1130 being extremely thin, and (iii) prevent leakage of gas (i.e., hydrogen gas and / or air). The first and second subgaskets 1310 and 1320 each have an electrode window to expose the first and second electrodes 1110 and 1120. That is, the first subgasket 1310 surrounds the first electrode 1110, and the second subgasket 1320 surrounds the second electrode 1120.

[0040] Each of the first and second subgaskets 1310 and 1320 may be formed by laminating a film having good heat resistance and chemical resistance in a temperature range from room temperature to 120° C., capable of withstanding a pressure of 100 torque or more, and having a relatively low gas permeability, onto the electrolyte membrane 1130. For example, each of the first and second subgaskets 1310 and 1320 may include a polyimide (PI)-based compound, a polyethylene (PE)-based compound, a polypropylene (PP)-based compound, a polyethylene terephthalate (PET)-based compound, a fluorinated ethylene propylene (FEP)-based compound, a polyethylene naphthalate (PEN)-based compound, or a mixture of two or more of these. A structure including the electrolyte membrane 1130, the first and second electrodes 1110, 1120, and the first and second subgaskets 1310, 1320 is also called a membrane electrode assembly, and a roll-to-roll continuous process may be adopted to improve the productivity of such a membrane electrode assembly. For example, the roll-to-roll continuous process may include the steps of (i) continuously forming the first electrode 1110 and the second electrode 1120 at a predetermined interval on the first and second surfaces of the electrolyte membrane 1130 provided in the form of a continuous film to obtain a catalyst coated membrane (CCM), (ii) laminating the first and second subgasket films, each having an electrode window formed at a predetermined interval, on both sides of the continuously provided CCM, and (iii) cutting the thus obtained laminate to form individual membrane electrode assemblies.

[0041] Also, as shown in FIG. 3, the fuel cell 1000 according to an embodiment of the present invention may further include a first gas diffusion layer 1410 between the first electrode 1110 and the first separator 1210, and a second gas diffusion layer 1420 between the second electrode 1120 and the second separator 1220. The main functions of the first and second gas diffusion layers 1410, 1420 are to (i) provide a gas diffusion path from the flow channels 1211, 1221 of the first and second separators 1210, 1220 to the first and second electrodes 1110, 1120 so that gas (i.e., hydrogen gas and / or air) can be easily and uniformly supplied to the first and second electrodes 1110, 1120, (ii) prevent flooding by allowing water, a by-product of the redox reaction, to be easily removed outside the first and second electrodes 1110, 1120, (iii) prevent a rapid decrease in the water content of the electrolyte membrane 1130 by storing a certain amount of water therein, and (iv) provide sufficient mechanical strength to the membrane electrode assembly 1100.

[0042] Each of the first and second gas diffusion layers 1410 and 1420 may be an electrically conductive porous member such as carbon paper, carbon cloth, carbon felt, metal paper, metal cloth, metal felt, etc. Also, as shown in FIG. 3, the fuel cell 1000 according to one embodiment of the present invention may further include a first gasket 1510 disposed between the first subgasket 1310 and the first separator 1210 and surrounding the first gas diffusion layer 1410, and a second gasket 1520 disposed between the second subgasket 1320 and the second separator 1220 and surrounding the second gas diffusion layer 1420.

[0043] The first and second gaskets 1510 and 1520 are intended to prevent leakage of gas (i.e., hydrogen gas and / or air) and may be made of materials such as, but not limited to, ethylene propylene diene monomer (EPDM), neoprene, urethane, acrylonitrile butadiene rubber (NBR), polytetrafluoroethylene (PTFE), etc.

Claims

1. A first electrode; A second electrode; an electrolyte membrane between the first and second electrodes; Including, the first electrode includes a first segment having a first durability and a second segment having a second durability lower than the first durability; The first segment has a double layer structure of first and second sub-layers sequentially formed over the electrolyte membrane, the second segment has a single layer structure; one of the first and second sublayers comprises a first catalyst; the other of the first and second sublayers and the second segment each includes a second catalyst different from the first catalyst; The first electrode is an anode where a hydrogen oxidation reaction occurs, The second electrode is a cathode where an oxygen reduction reaction occurs, the first catalyst is an oxygen evolution reaction (OER) catalyst; The second catalyst is a hydrogen oxidation reaction (HOR) catalyst; Membrane electrode assembly.

2. the first catalyst comprises a first support and first metal particles dispersed on the first support; the second catalyst comprises a second support and second metal particles dispersed on the second support; the first support is a crystalline carbon-based support or a conductive inorganic oxide support; The second support is an amorphous carbon-based support. The membrane electrode assembly of claim 1 .

3. A first separator; A second separator; a membrane electrode assembly according to claim 1 between said first and second separators; Including, the first electrode is disposed between the first separator and the electrolyte membrane; the first separator includes a first inlet for a first gas supplied to the first electrode, a first outlet for the first gas, and a first flow channel between the first inlet and the first outlet; the first durability is higher than the second durability, The first segment is a segment corresponding to the first inlet or the first outlet. fuel cell.

4. The electrolyte membrane has an active area and a non-active area surrounding the active area, the first electrode is disposed on a first surface of the active region; the second electrode is disposed on a second surface of the active region; The fuel cell comprises: a first subgasket disposed on a first surface of the non-active area and surrounding the first electrode; a second subgasket disposed on a second surface of the non-active area and surrounding the second electrode; a first gas diffusion layer between the first electrode and the first separator; a second gas diffusion layer between the second electrode and the second separator; Further comprising: The fuel cell according to claim 3.

5. a first gasket disposed between the first subgasket and the first separator and surrounding the first gas diffusion layer; a second gasket disposed between the second subgasket and the second separator and surrounding the second gas diffusion layer; Further comprising:

5. The fuel cell according to claim 4.

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