Membrane-electrode assembly, method for manufacturing same, and electrochemical cell comprising same

Abstract

The present disclosure relates to a membrane-electrode assembly, a method for manufacturing same, and an electrochemical cell comprising same. More specifically, by introducing a bonding layer containing a polyphenol compound having adhesive strength under moisture, the membrane-electrode assembly may have improved interfacial bonding between an electrode and a polymer electrolyte membrane and stability, without performance degradation, and improved chemical durability due to the removal of radicals generated when the electrochemical cell is in operation.

Description

Membrane-electrode assembly, method of manufacturing the same, and electrochemical cell including the same

[0001] The present disclosure relates to a membrane-electrode assembly, a method for manufacturing the same, and an electrochemical cell including the same. More specifically, by introducing a bonding layer comprising a polyphenol compound having adhesive properties under moisture, the membrane-electrode assembly can improve interfacial bonding and stability between the electrode and the polymer electrolyte membrane without performance degradation, and can improve chemical durability by eliminating radicals generated during the operation of the electrochemical cell.

[0002] The present disclosure relates to the results of a project (Project No.: 00418612) carried out with the support of the Ministry of Trade, Industry and Energy (MOTIE) and the Korea Energy Technology Evaluation Institute (KETEP).

[0003] In order to address the problems of fossil fuel depletion and environmental pollution, efforts are being made to conserve fossil fuels by improving usage efficiency or to apply renewable energy to more fields.

[0004] For example, fuel cells, which directly convert chemical reaction energy—such as the oxidation / reduction reactions of hydrogen and oxygen contained in hydrocarbon fuels like methanol, ethanol, and natural gas—into electrical energy, and water electrolysis cells, which produce hydrogen and oxygen by electrochemically decomposing water, are attracting attention as next-generation clean energy technologies to replace fossil fuels.

[0005] These fuel cells and water electrolysis cells are commonly referred to as electrochemical cells. Among them are Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and Polymer Electrolyte Membrane Water Electrolysis Cells (PEMWEs), which use a polymer electrolyte membrane as a separator. The Membrane Electrode Assembly (MEA), a core component of these PEMFCs and PEMWEs, has a structure in which an electrode for oxidation and an electrode for reduction are located on opposite sides of a polymer electrolyte membrane.

[0006] Generally, membrane-electrode assemblies are manufactured primarily by transferring electrodes onto both sides of a polymer electrolyte membrane at high temperatures and high pressures; however, in this case, performance and durability may be degraded due to the non-uniform and weak interface between the polymer electrolyte membrane and the electrode.

[0007] In particular, when the types of ion conductors included in the electrode and the ion conductors included in the polymer electrolyte membrane within the membrane-electrode assembly are different, transferability may be reduced due to low miscibility between the materials and differences in glass transition temperatures, which can consequently lead to electrode detachment and severe degradation of durability.

[0008] According to one embodiment, by introducing a bonding layer comprising a polyphenol compound having adhesive properties under moisture, the membrane-electrode assembly improves interfacial bonding and stability between the electrode and the polymer electrolyte membrane without performance degradation, and removes radicals generated during the operation of the electrochemical cell, thereby improving chemical durability. The present invention provides a membrane-electrode assembly, a method for manufacturing the same, and an electrochemical cell comprising the same.

[0009] One embodiment provides a membrane-electrode assembly comprising: a first electrode where an oxidation reaction occurs; a second electrode where a reduction reaction occurs; a polymer electrolyte membrane located between the first electrode and the second electrode; and a junction layer located between the first electrode and the polymer electrolyte membrane, or between the second electrode and the polymer electrolyte membrane, or between the first electrode and the polymer electrolyte membrane and between the second electrode and the polymer electrolyte membrane, and comprising a polyphenol compound and a first ion conductor.

[0010] Another embodiment provides a method for manufacturing a membrane-electrode assembly comprising: a step of forming a bonding layer by applying a composition for forming a bonding layer onto a first electrode where an oxidation reaction occurs, a second electrode where a reduction reaction occurs, or both electrodes; and a step of bonding a polymer electrolyte membrane to the first electrode with the bonding layer formed thereon, the second electrode with the bonding layer formed thereon, or both electrodes with the bonding layer formed thereon, wherein the polymer electrolyte membrane is located between the first electrode and the second electrode, and the bonding layer comprises a polyphenol compound and a first ion conductor.

[0011] Another embodiment provides an electrochemical cell comprising the aforementioned membrane-electrode assembly.

[0012] In one embodiment, a membrane-electrode assembly can have improved interfacial adhesion and stability between the electrode and the polymer electrolyte membrane without performance degradation by introducing a bonding layer containing a polyphenol compound having adhesive properties under moisture, and can have improved chemical durability by removing radicals generated during the operation of the electrochemical cell.

[0013] FIG. 1 is a schematic diagram showing a membrane-electrode assembly (MEA) according to one embodiment.

[0014] FIG. 2 is a schematic diagram showing the interface structure of a polymer electrolyte membrane, a bonding layer, and an electrode in a membrane-electrode assembly according to one embodiment.

[0015] Figure 3 is a photograph showing the results of the hydrothermal evaluation of the membrane-electrode assembly prepared in Example 2.

[0016] Figure 4 is a photograph showing the results of the hydrothermal evaluation of the membrane-electrode assembly prepared in Comparative Example 2.

[0017] Hereinafter, embodiments of the present disclosure are described in detail so that those skilled in the art to which the present disclosure pertains can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein.

[0018] In this specification, "combination thereof" means a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, a reaction product, etc.

[0019] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0020] Unless otherwise defined, "substitution" means that a hydrogen atom is deuterium, a halogen group, a hydroxyl group, a cyano group, a nitro group, -NRR' (wherein R and R' are each independently hydrogen, a substituted or unsubstituted C1 to C30 saturated or unsaturated aliphatic hydrocarbon group, a substituted or unsubstituted C3 to C30 saturated or unsaturated alicyclic hydrocarbon group, or a substituted or unsubstituted C6 to C30 aromatic hydrocarbon group), -SiRR'R (wherein R, R', and R' are each independently hydrogen, a substituted or unsubstituted C1 to C30 saturated or unsaturated aliphatic hydrocarbon group, a substituted or unsubstituted C3 to C30 saturated or unsaturated alicyclic hydrocarbon group, or a substituted or unsubstituted C6 to C30 aromatic hydrocarbon group), a C1 to C30 alkyl group, a C1 to C10 haloalkyl group, C1 to It means being substituted with a C10 alkylsilyl group, a C3 to C30 cycloalkyl group, a C6 to C30 aryl group, a C1 to C20 alkoxy group, or a combination thereof. "Unsubstituted" means that the hydrogen atom remains as a hydrogen atom without being replaced by another substituent.

[0021] "alkyl group" means a substituted or unsubstituted straight-chain or branched-chain aliphatic hydrocarbon group unless otherwise noted. An alkyl group may be a "saturated alkyl group" that does not contain a double or triple bond.

[0022] For example, the alkyl group may be a C1 to C8 alkyl group, and for example, may be a C1 to C7 alkyl group, a C1 to C6 alkyl group, a C1 to C5 alkyl group, or a C1 to C4 alkyl group. For example, the C1 to C4 alkyl group may be a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, or a tert-butyl group, or a 2,2-dimethylpropyl group.

[0023] "Akylene group" means, unless otherwise noted, a divalent hydrocarbyl group having a specific number of carbon atoms capable of linking two other groups, substituted or unsubstituted, in a straight or branched chain. An alkylene group is -(CH2) n -(Here, n is an integer from 1 to 8, for example, n is an integer from 1 to 4) can be referred to.

[0024] For example, the alkylene group may be a C1 to C8 alkylene group, and for example, may be a C1 to C7 alkylene group, a C1 to C6 alkylene group, a C1 to C5 alkylene group, or a C1 to C4 alkylene group. For example, the C1 to C4 alkylene group may be a methylene group, an ethylene group, a propylene group, an isopropylene group, an n-butylene group, an isobutylene group, a sec-butylene group, or a tert-butylene group or a 2,2-dimethylpropylene group.

[0025] "Heterocycloalkyl group" means a cyclic aliphatic saturated hydrocarbon group containing at least one heteroatom comprising N, O, S, P, Si, or a combination thereof within the cycloalkyl group, unless otherwise described. Two or more heterocycloalkyl groups may be directly connected through sigma bonds, or if the heterocycloalkyl group comprises two or more rings, the two or more rings may be fused together. If the heterocycloalkyl group is a fused ring, each ring may contain one to three heteroatoms.

[0026] For example, the heterocycloalkyl group may be a C3 to C20 heterocycloalkyl group, for example, a C3 to C10 heterocycloalkyl group, a C3 to C8 heterocycloalkyl group, a C3 to C7 heterocycloalkyl group, a C3 to C6 heterocycloalkyl group, a C3 to C5 heterocycloalkyl group, or a C3 to C4 heterocycloalkyl group. For example, the heterocycloalkyl group may be pyrrolidine, tetrahydrofuran, tetrahydrothiophene, or piperidine.

[0027] "Aryl group" means a substituted or unsubstituted aromatic ring in which, unless otherwise noted, all elements of a cyclic substituent have p-orbitals and these p-orbitals form a conjugate, and includes monocyclic or fused polycyclic rings (i.e., rings that share adjacent pairs of carbon atoms).

[0028] For example, the aryl group may be a C6 to C20 aryl group, for example, a C6 to C10 aryl group, a C6 to C8 aryl group, or a C6 to C7 aryl group. For example, the aryl group may be benzene, biphenyl, naphthalene, anthracene, phenanthrene, pyrene, or peylene.

[0029] "Alkenyl group" means a substituted or unsubstituted straight-chain or branched-chain aliphatic hydrocarbon group containing one or more double bonds, unless otherwise described. For example, the alkenyl group may be a C2 to C8 alkenyl group, and may be, for example, a vinyl group, an allyl group, a 1-propenyl group, a 1-methyl-1-propenyl group, a 2-propenyl group, a 2-methyl-2-propenyl group, a 1-butenyl group, a 2-butenyl group, or a 3-butenyl group.

[0030] "Alkenylene group" means, unless otherwise noted, a divalent hydrocarbyl group having a specific number of carbon atoms capable of linking two other groups, substituted or unsubstituted, straight-chain or branched-chain, containing one or more double bonds. The alkenylene group is -(CH=CH) n -(Here, n is an integer from 1 to 8, for example, n is an integer from 1 to 4) can be referred to.

[0031] For example, the alkenylene group may be a C2 to C8 alkenylene group, and for example, may be a C2 to C7 alkenylene group, a C2 to C6 alkenylene group, a C2 to C5 alkenylene group, or a C2 to C4 alkenylene group. For example, the C2 to C4 alkenylene group may be an ethylene group, a propene-1-ylene group, a propene-2-ylene group, a butene-1,4-ylene group, or a butene-2,3-ylene group.

[0032] "Halo" or "halogen group" means a fluorine group (-F), a chlorine group (-Cl), a bromine group (-Br), or an iodine group (-I), unless otherwise noted.

[0033] "Arylene group" means a functional group having two or more valencies formed by the removal of at least two hydrogens from one or more aromatic rings, optionally including one or more substituents.

[0034] "Alkylene carboxyl group" means, unless otherwise noted, an alkylene group (-CH2-)- n It has a structure in which a carboxyl group (-COOH) is bonded, where the alkylene group is as described above.

[0035] Membrane-electrode assembly

[0036] In one embodiment, a membrane-electrode assembly is provided comprising: a first electrode where an oxidation reaction occurs; a second electrode where a reduction reaction occurs; a polymer electrolyte membrane located between the first electrode and the second electrode; and a junction layer located between the first electrode and the polymer electrolyte membrane, or between the second electrode and the polymer electrolyte membrane, or between the first electrode and the polymer electrolyte membrane and between the second electrode and the polymer electrolyte membrane, and comprising a polyphenol compound and a first ion conductor.

[0037] The above membrane-electrode assembly can typically be applied to an electrochemical cell, for example, a fuel cell or a water electrolysis cell.

[0038] The membrane-electrode assembly of such an electrochemical cell includes an electrode where an oxidation reaction takes place and an electrode where a reduction reaction takes place. Although these electrodes may be referred to differently in fuel cells or water electrolysis cells, in this specification, the electrode where the oxidation reaction takes place is collectively referred to as the first electrode, and the electrode where the reduction reaction takes place is collectively referred to as the second electrode.

[0039] FIG. 1 is a schematic diagram showing a membrane-electrode assembly according to one embodiment.

[0040] Referring to FIG. 1, the membrane-electrode assembly (100) comprises a first electrode (10), a second electrode (20), a polymer electrolyte membrane (30) located between the first electrode (10) and the second electrode (20), and a bonding layer (40 / 41,42) located between the first electrode (10) and the polymer electrolyte membrane (30) and between the second electrode (20) and the polymer electrolyte membrane (30). A membrane-electrode assembly according to one embodiment includes a bonding layer located between the first electrode and the polymer electrolyte membrane and between the second electrode and the polymer electrolyte membrane, but is not limited to FIG. 1 and may be located only between the first electrode and the polymer electrolyte membrane, or only between the second electrode and the polymer electrolyte membrane as described above.

[0041] Attempts have been made to improve interfacial bonding between the polymer electrolyte membrane and the electrode within the membrane-electrode assembly of an electrochemical cell by introducing plasticizers or adhesives, or by introducing physical bonding through interlocking structures. However, the former may result in reduced performance and durability, while the latter may be disadvantageous for commercialization due to process difficulties.

[0042] To solve this, a membrane-electrode assembly according to one embodiment can improve interfacial bonding and stability between a polymer electrolyte membrane and an electrode without performance degradation and without causing the above problem by introducing a bonding layer containing a polyphenol compound, and can improve chemical durability by removing radicals generated during the operation of an electrochemical cell.

[0043] The details regarding the above-mentioned bonding layer, first electrode, second electrode, and polymer electrolyte membrane are described below.

[0044] bonding layer

[0045] The bonding layer comprises a polyphenol compound and a first ion conductor. By including the polyphenol compound in a bonding layer according to one embodiment, the interfacial bonding and stability between the polymer electrolyte membrane and the electrode can be improved without performance degradation.

[0046] The above polyphenol compound may contain two or more hydroxyl groups.

[0047] For example, the polyphenol compound may include a first compound in which one aromatic hydrocarbon compound is substituted with two or more hydroxyl groups; a second compound in which one aromatic hydrocarbon compound is substituted with two or more hydroxyl groups and one or more carboxyl groups; a third compound in which the first compound and a cyclic compound are bonded together within one molecule; a fourth compound in which the second compound and a cyclic compound are bonded together within one molecule; or a combination thereof.

[0048] The first compound mentioned above refers to a compound in which one aromatic hydrocarbon compound is substituted with two or more hydroxyl groups.

[0049] The first compound above may include a compound represented by Chemical Formula 1 below, a compound represented by Chemical Formula 2, or a combination thereof.

[0050] [Chemical Formula 1]

[0051]

[0052] In Chemical Formula 1, R 11 to R 15 is each independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and R 11 to R 15 At least two of them are hydroxyl groups. The substituted or unsubstituted alkyl group may be a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. As an example, R 11 to R 15Each can independently be hydrogen, an unsubstituted alkyl group, or a hydroxyl group.

[0053] [Chemical Formula 2]

[0054]

[0055] In Chemical Formula 2, R 21 to R 26 is each independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and R 21 to R 26 At least two of them are hydroxyl groups. For example, the above R 21 to R 26 Each may independently be hydrogen, an unsubstituted alkyl group, or a hydroxyl group. Specific details regarding the substituted or unsubstituted alkyl group are as described above.

[0056] The first compound above may include a compound represented by Chemical Formula 2, wherein R in Chemical Formula 2 21 to R 26 Three of them are hydroxyl groups and the rest can be hydrogen.

[0057] The second compound refers to a compound in which one aromatic hydrocarbon compound is substituted with two or more hydroxyl groups and one or more carboxyl groups.

[0058] The second compound above may include a compound represented by the following chemical formula 3, a compound represented by the chemical formula 4, or a combination thereof.

[0059] [Chemical Formula 3]

[0060]

[0061] In Chemical Formula 3, R 31 to R 35 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and R 31 to R 35 At least two of them are hydroxyl groups, and R 31 to R35 At least one of them is a carboxyl group, or a substituted or unsubstituted alkylene carboxyl group. Specific details regarding the substituted or unsubstituted alkyl group are as described above, and the substituted or unsubstituted alkylene carboxyl group may be a carboxyl group connected to a substituted or unsubstituted alkylene group having 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. As an example, R 31 to R 35 Each can independently be hydrogen, an unsubstituted alkyl group, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, or an aldehyde group.

[0062] [Chemical Formula 4]

[0063]

[0064] In Chemical Formula 4, R 41 to R 46 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and R 41 to R 46 At least two of them are hydroxyl groups, and at least one is a carboxyl group or a substituted or unsubstituted alkylene carboxyl group. Here, specific details regarding the substituted or unsubstituted alkyl group and the substituted or unsubstituted alkylene carboxyl group are as described above. As an example, the above R 41 to R 46 Each can independently be hydrogen, an unsubstituted alkyl group, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, or an aldehyde group.

[0065] The second compound above may include a compound represented by Chemical Formula 4. As an example, R in Chemical Formula 4 41 to R 46Of these, two are hydroxyl groups, one is an unsubstituted alkylene carboxyl group, and the remainder may be hydrogen, where the unsubstituted alkylene carboxyl group may be a carboxyl group formed by the connection of a carbon-2 alkylene group and a carboxyl group. As another example, in Chemical Formula 4, R 41 to R 46 Three of them are hydroxyl groups, one is a carboxyl group, and the rest can be hydrogen.

[0066] The third compound refers to a compound in which the first compound and a saturated cyclic compound are bonded together within a single molecule. For example, the third compound may be a compound in which the first compound and a heterocyclic compound are bonded together within a single molecule. Here, the term "bonding" includes cases where the first compound and the heterocyclic compound are directly connected through chemical bonding, as well as cases where two rings are connected via other functional groups. Here, "saturated cyclic compound" refers to a compound that includes a ring structure, wherein the ring structure includes only single bonds, and "heterocyclic compound" refers to a compound in which an atom other than carbon is substituted into a ring structure consisting of single bonds.

[0067] Here, the heterocyclic compound may be a compound having a ring structure containing one or more oxygen atoms or sulfur atoms, and substituted with one or more hydroxyl groups, carboxyl groups, unsubstituted alkylene carboxyl groups, aldehyde groups, carbonyl groups, etc. The third compound may contain two or more of the first compound within a single molecule and may contain at least one of the heterocyclic compounds.

[0068] The above third compound may include a compound represented by the following chemical formula 5, a compound represented by the following chemical formula 6, or a combination thereof.

[0069] [Chemical Formula 5]

[0070]

[0071] In Chemical Formula 5, R 51 to R 56 Each is independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and X 51 To X 54 Each is independently an oxygen atom (O) or a sulfur atom (S), and R 51 to R 53 At least two of them are hydroxyl groups, and R 54 to R 56 At least two of them are hydroxyl groups. Also, X 51 and X 52 , and X 53 and X 54 They may be identical to each other. The specific details of the substituted or unsubstituted alkyl group are as previously described. For example, in Chemical Formula 5, R 51 to R 56 Each can independently be hydrogen, an unsubstituted alkyl group, or a hydroxyl group.

[0072] In Chemical Formula 5, R 51 to R 53 Two of them are hydroxyl groups and the other one is hydrogen, and R 54 to R 56 Two of them are hydroxyl groups and the other one is hydrogen, and X 51 To X 54 It can be an oxygen atom.

[0073] [Chemical Formula 6]

[0074]

[0075] In chemical formula 6, R 611 to R 614 , and R 619 to R 623 Each is independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and R 615 to R 618Each is independently a hydrogen, hydroxyl group, carboxyl group, substituted or unsubstituted alkylene carboxyl group, or aldehyde group, X6 is an oxygen atom (O) or a sulfur atom (S), and R 611 to R 614 At least two of them are hydroxyl groups, and R 619 to R 623 At least two of them are hydroxyl groups. The specific details of the substituted or unsubstituted alkyl group and the substituted or unsubstituted alkylene carboxyl group are as described above. For example, in Chemical Formula 6, R 611 to R 614 , and R 619 to R 623 is each independently hydrogen, an unsubstituted alkyl group, or a hydroxyl group, and R 615 to R 618 Each can independently be a hydrogen, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, or an aldehyde group.

[0076] In chemical formula 6, R 611 to R 614 Two of them are hydroxyl groups and the rest are hydrogen, and R 619 to R 623 Two of them are hydroxyl groups and the rest are hydrogen, and R 615 and R 616 Each is independently hydrogen or a hydroxyl group, and X6 can be an oxygen atom (O).

[0077] The fourth compound refers to a compound in which the second compound and a saturated cyclic compound are bonded together within a single molecule. Here, the meanings of "bonded" and "saturated cyclic compound" are as previously described.

[0078] The above-mentioned fourth compound may be a compound in which the above-mentioned second compound and a carbon cyclic compound or a heterocyclic compound are bonded together within a single molecule. For example, the carbon cyclic compound may be substituted with two or more hydroxyl groups and one or more carboxyl groups, and the carbon cyclic compound may exist in a structure in which it is bonded to the second compound by an ester bond by bonding with the oxygen atom of the carboxyl group of the second compound. As another example, the above-mentioned heterocyclic compound may be a compound having a ring structure containing one or more oxygen atoms and substituted with one or more hydroxyl groups, carboxyl groups, aldehyde groups, or combinations thereof, and the heterocyclic compound may exist in a structure in which it is bonded to the second compound by an ester bond by bonding with the oxygen atom of the carboxyl group of the second compound.

[0079] The above-mentioned fourth compound may include a compound represented by the following chemical formula 7, a compound represented by the following chemical formula 8, or a combination thereof.

[0080] [Chemical Formula 7]

[0081]

[0082] In Chemical Formula 7, R 711 to R 726 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and Z7 is an ester bond, a substituted or unsubstituted alkylene ester bond, or a substituted or unsubstituted alkenylene ester bond, and R 711 to R 721 At least two of them are hydroxyl groups, at least one is a carboxyl group, and R 722 to R 726 At least two of them are hydroxyl groups, and at least one is a carboxyl group, or a substituted or unsubstituted alkylene carboxyl group.

[0083] Here, the substituted or unsubstituted alkylene ester bond and the substituted or unsubstituted alkenylene ester bond refer to a case where an ester bond is connected to a substituted or unsubstituted alkylene group and a case where an ester bond is connected to a substituted or unsubstituted alkenylene group, respectively; the specific details regarding the substituted or unsubstituted alkylene group or the substituted or unsubstituted alkenylene group are as previously described, and as an example, it may be an alkylene group having 2 to 4 carbon atoms or an alkenylene group having 2 to 4 carbon atoms. In addition, the specific details regarding the substituted or unsubstituted alkyl group and the substituted or unsubstituted alkylene carboxyl group are as previously described. As an example, in Chemical Formula 7, R 711 to R 726 is each independently hydrogen, an unsubstituted alkyl group, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, or an aldehyde group, and Z7 is an ester bond, an unsubstituted alkylene ester bond, or an unsubstituted alkenylene ester bond, and R 711 to R 721 At least two of them are hydroxyl groups, at least one is a carboxyl group, and R 722 to R 726 At least two of them are hydroxyl groups, and at least one may be a carboxyl group or an unsubstituted alkylene carboxyl group.

[0084] The fourth compound may include a compound represented by the above chemical formula 7, wherein in chemical formula 7, R 711 to R 721 Of these, 3 are hydroxyl groups, 1 is a carboxyl group, and the rest are hydrogen, and R 722 to R 726 Two of them are hydroxyl groups and the rest are hydrogen, and Z7 may be an unsubstituted alkylene ester bond having 2 to 4 carbon atoms.

[0085] [Chemical Formula 8]

[0086]

[0087] In chemical formula 8, R 811 to R 820Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, an aldehyde group, a carbonyl group, or a substituent represented by the chemical formulas 8-1 to 8-2 below, X8 is an oxygen atom (O) or a sulfur atom (S), and R 811 to R 820 At least two of them are substituents represented by chemical formulas 8-1 to 8-2, and R 811 to R 820 At least two of them are hydroxyl groups. In addition, specific details regarding substituted or unsubstituted alkyl groups and substituted or unsubstituted alkylene carboxyl groups are as described above. As an example, in Chemical Formula 8, R 811 to R 820 Each is independently hydrogen, an unsubstituted alkyl group, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, an aldehyde group, a carbonyl group, or a substituent represented by the chemical formulas 8-1 to 8-2 below, and X8 may be an oxygen atom (O) or a sulfur atom (S).

[0088] [Chemical Formula 8-1]

[0089]

[0090] In chemical formula 8-1, R 8111 to R 8115 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and Z 81 is a portion directly bonded to the heterocyclic compound of Formula 8, for example, an ester bond, a substituted or unsubstituted alkylene ester bond, or a substituted or unsubstituted alkenylene ester bond, and R 8111 to R 8115At least two of them are hydroxyl groups. In addition, specific details regarding substituted or unsubstituted alkyl groups, substituted or unsubstituted alkylene carboxyl groups, substituted or unsubstituted alkylene ester bonds, and substituted or unsubstituted alkenylene ester bonds are as described above. As an example, in Chemical Formula 8-1, R 8111 to R 8115 Each is independently hydrogen, an unsubstituted alkyl group, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, or an aldehyde group, and Z 81 It may be an ester bond, an unsubstituted alkylene ester bond, or an unsubstituted alkenylene ester bond.

[0091] [Chemical Formula 8-2]

[0092]

[0093] In chemical formula 8-2, R 8211 to R 8219 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and Z 82 is the portion directly bonded to the heterocyclic compound of chemical formula 8, and Z 83 is the part where two aromatic hydrocarbons of chemical formula 8-2 are connected to each other, and as an example, Z 82 To Z 83 Each is independently an ester bond, a substituted or unsubstituted alkylene ester bond, or a substituted or unsubstituted alkenylene ester bond, and R 8211 to R 8219 At least four of them are hydroxyl groups. In addition, specific details regarding substituted or unsubstituted alkyl groups, substituted or unsubstituted alkylene carboxyl groups, substituted or unsubstituted alkylene ester bonds, and substituted or unsubstituted alkenylene ester bonds are as described above. As an example, in Chemical Formula 8-2, R 8211 to R 8219Each is independently hydrogen, an unsubstituted alkyl group, a hydroxyl group, a carboxyl group, an unsubstituted alkylene carboxyl group, or an aldehyde group, and Z 82 is the portion directly bonded to the heterocyclic compound of chemical formula 8, and Z 83 is the part where two aromatic hydrocarbons of chemical formula 8-2 are connected to each other, and as an example, Z 82 To Z 83 Each can independently be an ester bond, an unsubstituted alkylene ester bond, or an unsubstituted alkenylene ester bond.

[0094] The fourth compound may include a compound represented by the above chemical formula 8, wherein in chemical formula 8, R 811 to R 820 Two of them are hydroxyl groups, three are substituents represented by chemical formulas 8-1 to 8-2, and the remainder is hydrogen, and X8 can be an oxygen atom (O). Also, R 811 to R 820 Of the three, two may be substituents represented by Chemical Formula 8-1, and the remaining one may be a substituent represented by Chemical Formula 8-2. Also, in Chemical Formula 8-1, R 8111 to R 8115 Three of them are hydroxyl groups, the rest are hydrogen, and Z 81 can be an ester bond or an unsubstituted alkylene ester bond, and in Formula 8-2, R 8211 to R 8219 Five of them are hydroxyl groups and the rest are hydrogen, and Z 82 To Z 83 It can be an ether bond.

[0095] The above polyphenol compound may include pyrogallol, caffeic acid, gallic acid, ellagic acid, catechin, chlorogenic acid, tannic acid, or a combination thereof.

[0096] Catechol groups, galol groups, and other groups present in these polyphenol compounds can form strong non-covalent bonds with various molecules through hydrogen bonding and hydrophobic bonding, thereby inducing bonding between the polymer electrolyte membrane and the junction layer, and between the electrode and the ion conductor of the junction layer, which can improve stability.

[0097] The above polyphenol compound may be included in an amount of 0.3 to 15 parts by weight per 100 parts by weight of the first ion conductor, for example, 0.5 to 15 parts by weight, 1 to 15 parts by weight, 3 to 15 parts by weight, 5 to 15 parts by weight, 7 to 15 parts by weight, or 9 to 13 parts by weight. When the content of the above polyphenol compound satisfies the above range, enhancement of membrane-electrode interfacial stability can be expected without a decrease in ion conductivity. Meanwhile, if the amount of the above polyphenol compound is less than 0.3 parts by weight per 100 parts by weight of the first ion conductor, the effect of improving membrane-electrode interfacial stability may be insufficient, and if it exceeds 15 parts by weight, gelation may occur, making it difficult to use in the process.

[0098] The first ion conductor described above can improve bonding properties by binding to the hydroxyl groups of a polyphenol compound and may be added to provide improved bonding performance even after undergoing a high-temperature and high-pressure transfer process or during the operation of an electrochemical cell. Here, the first ion conductor is described as "first ion conductor" merely to distinguish it from the ion conductor included in the electrode and membrane-electrode assembly, and does not necessarily indicate that it is different from the ion conductor included in the electrode and membrane-electrode assembly.

[0099] The first ion conductor may include a fluorine-based ion conductor, a hydrocarbon-based ion conductor, or a combination thereof, and the first ion conductor may have a cation exchanger or an anion exchanger.

[0100] The above cation exchanger is a functional group capable of transferring cations such as protons, and may be an acidic group such as, for example, a sulfonic acid group, a carboxyl group, a boronic acid group, a phosphate group, an imide group, a sulfonimide group, a sulfonamide group, etc.

[0101] The above anion exchanger is a functional group capable of transferring anions such as hydroxyl ions, carbonate ions, or bicarbonate ions, and may be, for example, a quaternary ammonium group, a quaternary phosphate group, an imidazolinium group, a pyridinium group, a sulfonium group, etc.

[0102] The above fluorine-based ion conductor is (i) a fluorine-based polymer having fluorine in the main chain having a cation exchanger or an anion exchanger, or (ii) a partially fluorinated polymer such as a polystyrene-graft-ethylene-tetrafluoroethylene copolymer, a polystyrene-graft-polytetrafluoroethylene copolymer, etc.

[0103] For example, the above-mentioned fluorine-based ion conductor comprises (i) poly(perfluorosulfonic acid), (ii) poly(perfluorocarboxylic acid), (iii) a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, and (iv) defluorinated sulfated polyetherketone, but is not limited to these.

[0104] The above hydrocarbon-based ion conductor may, for example, include imidazole, benzimidazole, polybenzoxazole, polybenzthiazole, polyamide, polyamideimide, polyimide, polyimidesulfone, polyacetal, polyethylene, polypropylene, acrylic resin, polyester, polysulfone, polyether, polyetherimide, polyarylene ether-based polymer, polyarylene ketone, polyarylenephosphine oxide, polyester, polyethersulfone, polycarbonate, polystyrene, polyphenylene-based polymer, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfidesulfone, polyparaphenylene, polyetheretherketone, polyetherketone, polyetherphosphine oxide, polyarylethersulfone, polyphosphazene, polyphenylquinoxaline, or a combination thereof in a main chain, and may include at least a cation exchanger or anion exchanger in a side chain connected to the main chain. Here, the above polysulfone, polyethersulfone, polyetherketone, etc. refer to structures having sulfone bonds and / or ether bonds and / or ketone bonds in the molecular chain. Since the details regarding the above cation exchanger and the above anion exchanger can be applied in the same way as described above, they are omitted below.

[0105] For example, the hydrocarbon-based ion conductor is 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 polyether sulfone, sulfonated polyether ketone, sulfonated sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, sulfonated polyphenylene sulfide sulfone nitrile, sulfonated polyarylene ether, sulfonated polyarylene ether nitrile,and sulfonated polyarylene ether sulfone ketones, but are not limited to these.

[0106] The equivalent weight (EW) of the first ion conductor may be 500 g / eq to 1100 g / eq, for example, 600 g / eq to 1000 g / eq. The equivalent weight of the first ion conductor is the molecular mass of the first ion conductor per ion-conducting functional group contained in the first ion conductor. When the equivalent weight of the first ion conductor satisfies the above range, a reduction in inter-interface resistance and the maintenance effect of the hydrogen ion conduction channels of the membrane-electrode assembly under various operating conditions can be expected. On the other hand, if the equivalent weight of the first ion conductor is less than 500 g / eq, gelation may occur due to an excessive increase in the binding between the first ion conductor and the polyphenol compound, making it difficult to use in the process, and if it exceeds 1100 g / eq, hydrogen ion conductivity may decrease under low-humidity operating conditions.

[0107] The ion exchange capacity (IEC) of the first ion conductor may be 0.8 meq / g to 5.5 meq / g, for example, 0.9 meq / g to 5.0 meq / g, 0.9 meq / g to 3.5 meq / g, or 0.9 meq / g to 2.0 meq / g. When the ion exchange capacity of the first ion conductor satisfies the above range, a bonding layer having stability under various operating conditions can be formed without a decrease in hydrogen ion conductivity.

[0108] The first ion conductor may be included in an amount of 65% to 99.6% by weight with respect to 100% by weight of the bonding layer, for example, in an amount of 70% to 99% by weight, 75% to 97% by weight, 80% to 95% by weight, or 85% to 92% by weight. When the content of the first ion conductor satisfies the above range, improvements in ion transport capability and interfacial bonding can be expected while minimizing the increase in resistance of the polymer electrolyte membrane.

[0109] The bonding layer may fill pores (surface recesses) formed on the surface of the first electrode, the second electrode, or both; pores existing at a certain depth from the surface of the first electrode, the second electrode, or both; or a combination thereof.

[0110] FIG. 2 is a schematic diagram showing the interface structure of a polymer electrolyte membrane (70), a bonding layer (60), and an electrode (50) in a membrane-electrode assembly (200) according to one embodiment.

[0111] Referring to FIG. 2, a bonding layer (60) is interposed between the polymer electrolyte membrane (70) of the membrane-electrode assembly and the electrode (50) containing catalyst particles (51) and an ionomer, and the bonding layer (60) may partially penetrate between the particles within the electrode (50) on the side of the polymer electrolyte membrane (70). FIG. 2 illustrates a bonding layer (60) according to one embodiment with respect to a bonding layer (61) located on the surface of the electrode and a bonding layer (62) that penetrates to a certain depth between the particles within the electrode, but it may exist only on the surface of the electrode, and one of the electrodes existing on both sides of the polymer electrolyte membrane may penetrate only on the surface of the electrode, while the other electrode may have a form that penetrates to a certain depth on the surface of the electrode. The form of the bonding layer is not limited to FIG. 2.

[0112] The thickness of the bonding layer may be 0.01 μm to 10 μm, for example, 0.01 μm to 5 μm. When the thickness of the bonding layer is within the above range, the bonding strength between the membrane and the electrode is improved while minimizing the increase in resistance of the polymer electrolyte membrane, thereby allowing for the expectation of improved performance and durability of the membrane-electrode assembly.

[0113] The mass per unit area of ​​the above bonding layer is 0.01 mg / cm² 2 to 2.0 mg / cm² 2 It can be, for example, 0.01 mg / cm² 2 to 1.0 mg / cm² 2 It is possible. If the mass per unit area of ​​the bonding layer is within the above range, stable maintenance of hydrogen ion conduction channels can be expected even under various operating conditions.

[0114] The thickness of the bonding layer filling the pores existing at a certain depth from the surfaces of the first electrode, the second electrode, or both may be 1% to 10% of the thickness of the first electrode or the second electrode, or 2% to 5%. When the thickness of the bonding layer filling the pores of the electrode satisfies the above range, the bonding effect and performance between the electrode and the bonding layer may be excellent. The thickness of the bonding layer filling the pores existing at a certain depth from the surface of the electrode may be an average depth or an average thickness, and may be an average value of the penetration depth or thickness relative to the total thickness of the electrode. Alternatively, it may be an average value per unit length at one cross-section of the electrode, and the % is a percentage value of the value obtained by dividing the average penetration depth of the bonding layer in units of length by the average thickness of the electrode in units of length.

[0115] The bonding layer can maximize the contact area between the catalyst and the polymer electrolyte membrane by filling the pores existing on the electrode surface or at a certain depth from the surface. There are no pores (or voids) between the polymer electrolyte membrane and the catalyst within the electrode, and an interface between the electrode and the bonding layer is formed along the surface curvature of the catalyst. Due to the widened interface area, the number of ion transfer pathways increases, and consequently, the adhesion strength between the electrode and the polymer electrolyte membrane can be improved.

[0116] The bonding layer may further include nanopowder.

[0117] The above nanopowder can impart functionality to the bonding layer without reducing the interfacial adhesion of the membrane-electrode assembly or increasing interfacial resistance, thereby overcoming the degradation of durability of the membrane-electrode assembly and improving performance. A polyphenol compound included in the bonding layer according to one embodiment can slow down the release rate by fixing the nanopowder through hydrogen bonding with the nanopowder.

[0118] The nano powder may be in the form of particles, and the average particle size of the nano powder may be 1 nm to 50 nm or 2 nm to 35 nm. When the average particle size of the nano powder is within the above range, it is uniformly dispersed within the bonding layer, and the membrane-electrode assembly can be implemented without a significant increase in resistance, and the occurrence of aggregation between nano powders, reduced dispersibility, and phase separation can be suppressed.

[0119] The above nanopowder may include a hydrophilic inorganic material, a radical scavenger, a catalyst for an oxygen evolution reaction (OER), or a combination thereof.

[0120] The above hydrophilic inorganic material can increase the water content of the membrane-electrode assembly and contribute to improving hydrogen ion conductivity under low humidity conditions. The above hydrophilic inorganic material may include SnO2 (tin oxide), fumed silica, clay, alumina, mica, zeolite, phosphotungstic acid, silicon tungstic acid, zirconium hydrogen phosphate, or a mixture thereof.

[0121] The radical scavenger may be uniformly dispersed within the junction layer and contribute to the stabilization of the membrane-electrode assembly. The radical scavenger may be an ion of a transition metal capable of suppressing the generation of hydroxyl radicals by decomposing hydrogen peroxide into water and oxygen, and may include cerium, ruthenium, palladium, silver, rhodium, yttrium, manganese, molybdenum, lead, vanadium, titanium, their ionic forms, their oxide forms, their salt forms, or mixtures thereof.

[0122] More specifically, the radical scavenger may include CeO2, MnO2, CsO2, ZrO2, Ru, Ag, RuO2, WO3, Fe3O4, CePO4, CrPO4, AlPO4, FePO4, CeF3, FeF3, Ce2(CO3)3·8H2O, Ce(CHCOO)3·H2O, CeCl3·6H2O, Ce(NO3)6·6H2O, Ce(NH4)2(NO3)6, Ce(NH4)4(SO4)4·4H2O, Ce(CH3COCHCOCH3)3·3H2O, Fe-porphyrin, Co-porphyrin, or a mixture thereof.

[0123] The above-mentioned catalyst for the oxygen generation reaction can be atomized and uniformly dispersed within the bonding layer to improve the durability of the electrode through an effective water splitting reaction. The catalyst for the oxygen evolution reaction described above may include platinum, gold, palladium, rhodium, iridium, ruthenium, osmium, platinum alloys, alloys thereof, or mixtures thereof, and the platinum alloy may include Pt-Pd, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ru, Pt-Ru-W, Pt-Ru-Mo, Pt-Ru-Rh-Ni, Pt-Ru-Sn-W, Pt-Co, Pt-Co-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-Co-S, Pt-Co-P, Pt-Fe, Pt-Fe-Ir, Pt-Fe-S, Pt-Fe-P, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Ni, Pt-Ni-Ir, Pt-Cr, Pt-Cr-Ir, or combinations thereof. It is possible.

[0124] In the bonding layer, the nano powder may be included in an amount of 0.1 to 30 parts by weight per 100 parts by weight of the first ion conductor, for example, 0.2 to 20 parts by weight, 0.3 to 10 parts by weight, 0.4 to 5 parts by weight, or 0.5 to 2 parts by weight. When the content of the nano powder satisfies the above range, the formation of a uniformly dispersed bonding layer without precipitation of the nano powder can be expected.

[0125] First electrode and second electrode

[0126] An oxidation reaction occurs at the first electrode. For example, in a fuel cell, the first electrode refers to the electrode where an oxidation reaction such as the reaction equation 1-1 below occurs, and in a water electrolysis cell, it refers to the electrode where an oxidation reaction such as the reaction equation 2-1 below occurs. For convenience, the first electrode and the second electrode in the above fuel cell and water electrolysis cell are described based on a polymer electrolyte membrane fuel cell and a polymer electrolyte membrane water electrolysis cell containing a polymer electrolyte membrane, and are not limited to reactions such as those below occurring in the fuel cell and water electrolysis cell. For example, a case in which hydroxide ions are transported instead of hydrogen ions may be included in one embodiment. Even in the case of transporting hydroxide ions, they may correspond to the first electrode and the second electrode based on the electrode where the oxidation reaction occurs and the electrode where the reduction reaction occurs. The above first electrode may be called an anode.

[0127] [Reaction Equation 1-1]

[0128] H2→ 2H + + 2e -

[0129] [Reaction Equation 2-1]

[0130] 2H2O → O2 + 4H + + 4e -

[0131] A reduction reaction occurs at the second electrode. For example, in a fuel cell, the second electrode is the electrode where a reduction reaction as shown in Equation 1-2 below takes place, and in a water electrolysis cell, it refers to the electrode where a reduction reaction as shown in Equation 2-2 below takes place. The second electrode can be called the cathode in an electrochemical cell.

[0132] [Reaction Equation 1-2]

[0133] O2+ 4H + + 4e - → 2H2O

[0134] [Reaction Equation 2-2]

[0135] 2H + + 2e -→ H2

[0136] The first electrode and the second electrode may each independently include a catalyst layer comprising a catalyst and an ion conductor.

[0137] The above catalyst may include a precious metal or a precious metal oxide.

[0138] The above precious metal may be a platinum-based precious metal.

[0139] Platinum (Pt) and / or a Pt-M alloy may be used as the platinum-based precious metal. M may be 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), or rhodium (Rh).

[0140] Specifically, as the above Pt-M alloy, 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-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, or a mixture thereof may be used. there is.

[0141] The above precious metal oxide may be iridium oxide, an oxide of an iridium alloy, or a combination thereof.

[0142] For example, the above precious metal oxide is IrO x (The above x is an integer from 1 to 3), IrMOx (M includes Ru, Pt, Sn, Se, Zn, Au, Te, Nb, or a combination thereof, and x is an integer from 1 to 3) or a combination thereof.

[0143] The catalyst may further include a first carrier supporting the precious metal or a second carrier supporting the precious metal oxide. The first carrier and the second carrier are intended to distinguish the carrier supporting the precious metal and the carrier supporting the precious metal oxide, respectively. The precious metal or precious metal oxide may be in the form of particles, and the precious metal particles may be located on the surface of the first carrier and may penetrate into the carrier while filling the internal pores of the first carrier. The precious metal oxide particles may also be located on the surface of the second carrier and may penetrate into the carrier while filling the internal pores of the second carrier.

[0144] The first carrier above may be a carbon-based carrier.

[0145] The carbon-based carrier may be graphite, super P, carbon fiber, carbon sheet, carbon black, Ketjen black, Denka black, acetylene black, carbon nanotube (CNT), carbon sphere, carbon ribbon, fullerene, activated carbon, carbon nanofiber, carbon nanowire, carbon nanoball, carbon nanohorn, carbon nanocage, carbon nanoring, ordered nano- / meso-porous carbon, carbon aerogel, mesoporous carbon, graphene, stabilized carbon, activated carbon, or a combination thereof.

[0146] The second carrier may be a metal oxide.

[0147] The metal oxide may be tungsten oxide, titanium oxide, nickel oxide, ruthenium oxide, tantalum oxide, tin oxide, cobalt oxide, or a combination thereof.

[0148] The above catalyst may be included in an amount of 20% to 80% by weight relative to 100% by weight of the electrode, but is not limited thereto.

[0149] The above ion conductor can play a role in improving adhesion within the electrode and ion transfer.

[0150] The above ion conductor may include fluorine-based ion conductors, hydrocarbon-based ion conductors, and combinations thereof, and the ion conductor may have a cation exchanger or an anion exchanger. The type of ion conductor included in the catalyst layer is the same as that described above for the first ion conductor included in the bonding layer.

[0151] The above ion conductor may be used in the form of a single material or a mixture, and may also be optionally used in combination with a non-conductive compound to further enhance adhesion to the polymer electrolyte membrane. The content of the non-conductive compound can be appropriately adjusted according to the intended use.

[0152] As the above non-conductive compound, at least one selected from polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride, copolymer of polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), dodecylbenzenesulfonic acid, and sorbitol may be used.

[0153] Commercially available examples of the above-mentioned ion conductors include Nafion and Aquivion.

[0154] The above ion conductor may be included in an amount of 10 to 70 parts by weight, or 20 to 60 parts by weight, relative to 100 parts by weight of the catalyst. If the content of the ion conductor is less than 10 parts by weight relative to 100 parts by weight of the catalyst, problems may arise such as reduced dispersibility and stability of the catalyst and decreased hydrogen ion conductivity. If it exceeds 60 parts by weight, the ion conductor may clump together, increasing mass transfer resistance, or cover the surface of the catalyst, causing a reduction in the active surface area, which may lead to a decrease in performance and durability.

[0155] The first electrode and the second electrode may each independently include only a catalyst layer containing the catalyst and an ion conductor (more specifically, a first catalyst layer included in the first electrode and a second catalyst layer included in the second electrode), or may include an electrode substrate together with the catalyst layer.

[0156] At this time, the electrode substrate can perform the role of supporting the electrode while diffusing fuel and oxidant into the catalyst layer.

[0157] The electrode substrate may include a micropore layer, a porous diffusion layer, or a combination thereof.

[0158] The above microporous layer serves to enhance the reactant diffusion effect and may generally include a conductive powder with a small particle size, for example, carbon powder, carbon black, acetylene black, activated carbon, metal oxide nanowire, carbon fiber, fullerene, carbon nanotube, carbon nanowire, carbon nanohorn, or carbon nano ring.

[0159] The above porous diffusion layer is porous titanium, carbon paper, carbon cloth, carbon felt, or metal cloth (referring to a porous film composed of a metal cloth in a fibrous state or a metal film formed on the surface of a cloth formed of polymer fibers).

[0160] The micropore layer and the porous diffusion layer may include known types in addition to those exemplified above.

[0161] polymer electrolyte membrane

[0162] The polymer electrolyte membrane is located between the first electrode and the second electrode. The polymer electrolyte membrane may have an ion exchange function that moves ions between the first electrode and the second electrode.

[0163] The above polymer electrolyte membrane may include an ion conductor.

[0164] The type of ion conductor included in the polymer electrolyte membrane is as described above regarding the first ion conductor included in the bonding layer, and the ion conductor included in the polymer electrolyte membrane may be the same or different from the ion conductor included in the first electrode and the second electrode, and the ion conductor included in the polymer electrolyte membrane may be the same or different from the first ion conductor included in the bonding layer.

[0165] The polymer electrolyte membrane may be in the form of a reinforced membrane comprising a porous support having a plurality of pores and an ion conductor filling the pores of the porous support.

[0166] The above porous support may be a fluorine-based support, a nanoweb support, or a combination thereof.

[0167] The above-mentioned fluorine-based support may correspond, for example, to expanded polytetrafluoroethylene (e-PTFE) having a microstructure of polymer fibrils or a microstructure in which nodes are interconnected by fibrils.

[0168] The above nanoweb support may be a support in which nanofibers are integrated in the form of a nonwoven fabric containing a number of pores.

[0169] Method for manufacturing a membrane-electrode assembly

[0170] In another embodiment, a method for manufacturing a membrane-electrode assembly is provided, comprising the steps of: applying a composition for forming a bonding layer to a first electrode where an oxidation reaction occurs, a second electrode where a reduction reaction occurs, or both electrodes to form a bonding layer; and bonding the first electrode with the bonding layer formed thereon, the second electrode with the bonding layer formed thereon, or both electrodes with the bonding layer formed thereon, to a polymer electrolyte membrane. The polymer electrolyte membrane is located between the first electrode and the second electrode, and the bonding layer comprises a polyphenol compound and a first ion conductor.

[0171] First, a bonding layer is formed by applying a composition for forming a bonding layer onto a first electrode where an oxidation reaction occurs, a second electrode where a reduction reaction occurs, or both electrodes.

[0172] The first electrode and the second electrode are as described above and can be manufactured according to a known method. For example, the first electrode and the second electrode can each be formed by independently preparing an electrode-forming composition comprising a catalyst, an ion conductor, and a solvent, and then using the same.

[0173] The above solvent may be water, a hydrophilic solvent, an organic solvent, or a mixture of one or more of these.

[0174] The above hydrophilic solvent may have one or more functional groups selected from alcohols, ketones, aldehydes, carbonates, carboxylates, carboxylic acids, ethers, and amides, comprising a straight-chain or branched saturated or unsaturated hydrocarbon having 1 to 12 carbon atoms as a main chain, and these may include an alicyclic or aromatic cyclocompound as at least part of the main chain. Specific examples include alcohols such as methanol, ethanol, isopropyl alcohol, ethoxyethanol, n-propyl alcohol, butyl alcohol, 1,2-propanediol, 1-pentanol, 1.5-pentanediol, 1.9-nonanediol, etc.; ketones such as heptanone, octanone, etc.; aldehydes such as benzaldehyde, tolualdehyde, etc.; and esters such as methylpentanoate, ethyl-2-hydroxypropanoate, etc. Carboxylic acids include pentanoic acid, heptanoic acid, etc.; ethers include methoxybenzene, dimethoxypropane, etc.; and amides include propanamide, butylamide, dimethylacetamide, etc.

[0175] The above organic solvent can be selected from N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, and mixtures thereof.

[0176] The above solvent may be contained in an amount of 40 to 99.7 weight% with respect to 100 weight% of the electrode forming composition.

[0177] As a specific example of the step of manufacturing the electrode using the above electrode-forming composition, the electrode can be manufactured by coating the electrode-forming composition onto a release film. Depending on the viscosity of the electrode-forming composition, it may be continuously transferred via a pump to a coater such as a die, gravure, bar, or comma coater, and then applied onto a decal film using methods such as slot die coating, bar coating, comma coating, screen printing, spray coating, doctor blade coating, or brushing, and dried to volatilize the solvent. The drying may be performed at 25°C to 90°C for 6 hours or more.

[0178] The above electrode may be a first electrode, a second electrode, or both electrodes.

[0179] The above composition for forming the bonding layer may include a polyphenol compound, a first ion conductor, and a solvent, and the type of the polyphenol compound and the type of the first ion conductor are as described above.

[0180] For example, the composition for forming the bonding layer can be prepared by mixing a first mixed solution of a polyphenol compound and a first solvent with a second mixed solution of a first ion conductor and a second solvent, and the first mixed solution and the second mixed solution can be mixed in a weight ratio of 5:5 to 1:9. When the weight ratio of the first mixed solution and the second mixed solution satisfies the above range, a stable composition can be formed without gelation. The first solvent and the second solvent may each independently use water, a hydrophilic solvent, an organic solvent, or a mixture of one or more of these, and the types of the hydrophilic solvent and the organic solvent are as described above.

[0181] The above composition for forming a bonding layer may include the polyphenol compound at a concentration of 0.1% to 10%, the first ion conductor at a concentration of 0.1% to 30%, and the solvent at a concentration of 60% to 99.8%. Here, concentration refers to percentage concentration, and percentage concentration can be calculated as the percentage of the mass of the solute relative to the mass of the solution.

[0182] The above composition for forming a bonding layer may further include nano powder, in which case the composition for forming a bonding layer may include the polyphenol compound at a concentration of 0.1% to 10%, the first ion conductor at a concentration of 0.1% to 30%, the nano powder at a concentration of 0.1% to 20%, and the solvent at a concentration of 40% to 99.7%.

[0183] The bonding layer can be formed by spray coating the bonding layer forming composition onto the first electrode, the second electrode, or both electrodes. When the bonding layer forming composition is applied by a spray coating method, the bonding layer does not penetrate excessively into the interior of the electrode, but penetrates to a certain depth from the electrode surface to fill in surface irregularities. In the spray method, since the bonding layer forming composition is applied to the electrode surface in a state where some solvent volatilizes and viscosity increases as it is sprayed, the amount penetrating into the interior of the electrode is not excessive, and pores present on the surface can be selectively filled.

[0184] The specific details regarding the bonding layer are as described above, so they will be omitted below.

[0185] Next, a first electrode with a bonding layer formed thereon, a second electrode with a bonding layer formed thereon, or both electrodes with bonding layers formed thereon, and a polymer electrolyte membrane are bonded.

[0186] Optionally, the electrode and release film having the bonding layer formed thereon can be cut to the required size and then bonded to the polymer electrolyte membrane.

[0187] A method of bonding the electrode and the polymer electrolyte membrane through the bonding layer can, for example, utilize a transfer method, and the transfer method can be performed by a metal press alone or by a hot pressing method in which heat and pressure are applied by attaching a soft plate of rubber material, such as silicone rubber, to a metal press.

[0188] The above transfer method is at 50℃ to 200℃ and 3 kgf / cm 2 Up to 50 kgf / cm² 2It can be carried out under the following conditions. If the transfer temperature is below 50°C, the bonding between the polymer electrolyte membrane and the electrode or between the polymer electrolyte membrane and the junction layer may not be properly formed, and if it exceeds 200°C, the functional groups (e.g., sulfonic acid groups) of the ion conductors included in the membrane-electrode assembly—more specifically, the polymer electrolyte membrane, the junction layer, and the first and second electrodes—may decompose, causing performance degradation. In addition, the transfer pressure is 3 kgf / cm² 2 If it is less than, the bonding between the polymer electrolyte membrane and the electrode or between the polymer electrolyte membrane and the junction layer may not be properly formed, and 50 kgf / cm² 2 If it exceeds, the electrode structure may collapse, causing performance degradation.

[0189] electrochemical cell

[0190] In another embodiment, an electrochemical cell comprising the membrane-electrode assembly is provided. The electrochemical cell may be a water electrolysis cell or a fuel cell as described above, and in addition to the configuration described above, any known configuration that may be included in a water electrolysis cell or a fuel cell may be used without limitation.

[0191] Hereinafter, embodiments are described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0192]

[0193] Example 1

[0194] A composition for forming a first electrode was prepared by mixing Pt / C (Tanaka, TEC10E50E) as a catalyst and Nafion® / H2O / 2-propanol dispersion as an ion conductor dispersion in a weight ratio of 88:12, and dispersing by stirring and ultrasonic methods.

[0195] The above first electrode forming composition is applied to the first surface of a Teflon release film at 0.1 mgPt / cm2 , 0.4 mgPt / cm² on the second surface 2 After applying using a doctor blade to achieve the desired result, the first electrode was prepared on the first surface and the second electrode on the second surface by drying at 60°C for 6 hours.

[0196] A composition for forming a bonding layer was prepared by mixing a first mixed solution of 5 wt% tannic acid and 95 wt% H2O as a polyphenol compound, and a second mixed solution of 5 wt% Nafion® and 95 wt% solvent as a first ion conductor in a weight ratio of 1:9. As the solvent for the second mixed solution, a mixture of H2O and 2-propanol in a weight ratio of 1:1 was used.

[0197] The above-described composition for forming a bonding layer is applied to the above-described first electrode and second electrode at room temperature (25℃) at 0.15 mg / cm² 2 A bonding layer with a thickness of 0.5 μm was formed on the surfaces of the first electrode and the second electrode by spray coating with an amount of [amount].

[0198] A fluorine-based polymer electrolyte membrane is interposed between the first electrode and the second electrode manufactured above, and at 160°C and 20 kgf / cm² 2 A membrane-electrode assembly was manufactured in which the first electrode and the second electrode were bonded to a polymer electrolyte membrane together with a bonding layer by applying heat and pressure for 3 minutes under the conditions and then peeling off the Teflon release film.

[0199] The content of the first ion conductor was about 90% by weight for 100% by weight of the bonding layer, and the content of the polyphenol compound in the bonding layer was about 11.11% by weight for 100% by weight of the first ion conductor.

[0200]

[0201] Example 2

[0202] In the above Example 1, a membrane-electrode assembly was prepared in substantially the same manner as in Example 1, except that a hydrocarbon-based polymer electrolyte membrane was used instead of a fluorine-based polymer electrolyte membrane.

[0203]

[0204] Example 3

[0205] In the above Example 1, a membrane-electrode assembly was prepared in substantially the same manner as in Example 1, except that gallic acid was used instead of tannic acid as a polyphenol compound.

[0206]

[0207] Example 4

[0208] In the above Example 1, a membrane-electrode assembly was prepared in substantially the same manner as in Example 1, except that a composition for forming a bonding layer was prepared by mixing cerium oxide (CeO2) with an average particle size of 25 μm as a nano powder at a ratio of 5 wt% to 100 wt% of a solution obtained by mixing the first mixed solution and the second mixed solution of Example 1 in a weight ratio of 1:9.

[0209] The content of the first ion conductor was about 89.1% by weight for 100% by weight of the bonding layer, the content of the polyphenol compound in the bonding layer was about 11.11 parts by weight for 100 parts by weight of the first ion conductor, and the content of the nano powder in the bonding layer was about 1.12 parts by weight for 100 parts by weight of the first ion conductor.

[0210]

[0211] Comparative Example 1

[0212] A membrane-electrode assembly was manufactured substantially identically to Example 1, except that a composition for forming a bonding layer was prepared in Example 1 and applied to the electrode to form a bonding layer. The membrane-electrode assembly according to Comparative Example 1 is one in which a first electrode, a fluorine-based polymer electrolyte membrane, and a second electrode are bonded together.

[0213]

[0214] Comparative Example 2

[0215] A membrane-electrode assembly was manufactured substantially identically to Example 2, except that a composition for forming a bonding layer was prepared in Example 2 and applied to the electrode to form a bonding layer. The membrane-electrode assembly according to Comparative Example 2 is a first electrode, a hydrocarbon-based polymer electrolyte membrane, and a second electrode bonded together.

[0216]

[0217] <Evaluation Example>

[0218] 1. Evaluation of the transfer rate of the membrane-electrode assembly

[0219] The hydrothermal evaluation of the membrane-electrode assemblies prepared in Example 2 and Comparative Example 2 above was evaluated as follows.

[0220] According to the membrane-electrode assembly manufacturing method described above, a fluorine-based polymer electrolyte membrane is interposed between the first electrode and the second electrode, and at 160°C and 20 kgf / cm² 2 After transferring by applying heat and pressure for 3 minutes under certain conditions, a membrane-electrode assembly in which the first electrode and the second electrode are bonded to a polymer electrolyte membrane together with a bonding layer is manufactured by peeling off the Teflon release film, and it was checked whether there were any remaining electrodes on the peeled release film.

[0221] The results are shown in Figures 3 and 4 below.

[0222] Referring to FIGS. 3 and 4, in the case of Example 2, which is prepared using a first electrode and a second electrode spray-coated on the surface of a composition for forming a bonding layer containing a polyphenol compound, it can be seen that a membrane-electrode assembly is cleanly formed on a release film without any residual electrode after a transfer process through hot pressing, whereas in the case of Comparative Example 2, which is not like that, it can be seen that there is a residual electrode on the release film.

[0223] Through this, it was confirmed that in the case of Example 2, which includes a bonding layer containing a polyphenol compound, complete transfer is possible even under transfer conditions of 160°C, which is lower than the glass transition temperature of a hydrocarbon ion conductor included in a conventional hydrocarbon polymer electrolyte membrane and does not decompose functional groups, due to the increased bonding strength between the polymer electrolyte membrane and the electrode interface compared to Comparative Example 2, which does not.

[0224]

[0225] 2. Performance Evaluation of Fuel Cells

[0226] The performance evaluation of the membrane-electrode assemblies prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was performed as follows, evaluating battery performance and chemical durability.

[0227] Active area 25 cm 2 The output performance of the membrane-electrode assembly was evaluated through IV measurements, using a membrane with a thickness of 15 μm. Specifically, to verify the output performance under actual fuel cell operating conditions, the membrane-electrode assembly was tested using a fuel cell unit cell evaluation device (Scribner 850 fuel cell test system). Under conditions of 65°C, hydrogen (100% RH) and air (100% RH) were supplied to the first and second electrodes, respectively, in amounts corresponding to Stoichiometry 1.5 / 2.0. The current density was measured at a voltage of 0.6 V, and a higher result value indicates superior output performance.

[0228] Chemical durability was evaluated by performing the OCV hold method for 500 hours under conditions of 90°C, RH 30%, and 50kPa after the initial performance evaluation of the membrane-electrode assembly, and then measuring the voltage loss for each. The measured values ​​are shown in Table 1 below. During the evaluation process, if the OCV loss was 20% or more, the evaluation was terminated.

[0229] Battery performance evaluation (A / cm) 2 )OCV Voltage Loss (%) Example 1 1.36 15 Example 2 1.28 20 (450 hours) Example 3 1.34 17 Example 4 1.33 10 Comparative Example 11.35 20 (240 hours) Comparative Example 21.10 20 (105 hours)

[0230] Referring to Table 1 above, in the case of Examples 1, 3, and 4, which are membrane-electrode assemblies based on fluorinated polymer electrolyte membranes with a bonding layer containing a polyphenol compound, it can be confirmed that they exhibit improved durability, with the OCV voltage loss evaluated to be less than 20% over 500 hours while maintaining equivalent performance in the battery performance evaluation compared to Comparative Example 1, which does not include a bonding layer. Meanwhile, the same trend can be confirmed in the results of the membrane-electrode assemblies based on hydrocarbon-based polymer electrolyte membranes of Example 2 and Comparative Example 2. Specifically, in the case of Example 2, which is a membrane-electrode assembly based on a hydrocarbon-based polymer electrolyte membrane with a bonding layer containing a polyphenol compound, it exhibits superior performance in the battery performance evaluation compared to Comparative Example 2, which does not include a bonding layer, and it can be confirmed that Example 2 takes 450 hours to reach an OCV voltage loss of 20%, compared to 105 hours for Comparative Example 2, showing improved durability.

[0231] Through this, it was confirmed that the introduction of a bonding layer containing a polyphenol compound with adhesive properties in water can improve battery performance to be equivalent or superior, regardless of the type of fluorine-based or hydrocarbon-based polymer electrolyte membrane, while also enhancing durability.

[0232]

[0233] 3. Evaluation of Hydrogen Permeability of Fuel Cells

[0234] For the membrane-electrode assemblies prepared in Examples 1 to 4 and Comparative Examples 1 to 2, hydrogen (100% RH) and nitrogen (100% RH) were supplied in amounts corresponding to Stoichiometry 1.5 / 2.0, respectively, under conditions of 80°C, and the hydrogen permeation current density of the polymer electrolyte membrane at 0.2 V was measured using the Linear Sweep Voltammetry (LSV) method with a Potentiostat (BioLogic), and the results are shown in Table 2.

[0235] Hydrogen permeation current density (mA / cm²) 2 Example 12.1 Example 20.2 Example 32.3 Example 42.0 Comparative Example 12.6 Comparative Example 20.5

[0236] Referring to Table 2 above, Examples 1, 3, and 4, which are membrane-electrode assemblies based on fluorine-based polymer electrolyte membranes with a junction layer containing a polyphenol compound, show lower hydrogen permeability compared to Comparative Example 1, which does not include a junction layer. This is because the introduction of a polyphenol compound capable of bonding with various molecules resulted in a higher density ion conductor network within the junction layer. Meanwhile, the same trend as above can be observed in the results of the hydrocarbon-based polymer electrolyte membrane-electrode assemblies of Example 2 and Comparative Example 2, which also show generally low hydrogen permeability due to the characteristics of the membrane material.

[0237]

[0238] Although preferred embodiments have been described in detail above, the scope of the rights is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the rights.

[0239] [Explanation of the symbol]

[0240] 10: First electrode 20: Second electrode

[0241] 30: Polymer electrolyte membrane 40, 41, 42: Binding layer

[0242] 50: Electrode 51: Catalyst particle

[0243] 60: Bonding layer 61: Bonding layer located on the surface of the electrode

[0244] 62: A bonding layer penetrating to a certain depth between particles within the electrode

[0245] 70: Polymer electrolyte membrane 100: Membrane-electrode assembly

Claims

1. A first electrode where an oxidation reaction takes place; A second electrode where a reduction reaction takes place; A polymer electrolyte membrane located between the first electrode and the second electrode; and It is located between the first electrode and the polymer electrolyte membrane, or between the second electrode and the polymer electrolyte membrane, or between the first electrode and the polymer electrolyte membrane and between the second electrode and the polymer electrolyte membrane. A bonding layer comprising a polyphenol compound and a first ion conductor; comprising Membrane-electrode assembly.

2. In Paragraph 1, The above polyphenol compound comprises two or more hydroxyl groups, Membrane-electrode assembly.

3. In Paragraph 1, The above polyphenol compound comprises: a first compound in which one aromatic hydrocarbon compound is substituted with two or more hydroxyl groups; a second compound in which one aromatic hydrocarbon compound is substituted with two or more hydroxyl groups and one or more carboxyl groups; a third compound in which the first compound and a cyclic compound are bonded together within one molecule; a fourth compound in which the second compound and a cyclic compound are bonded together within one molecule; or a combination thereof. Membrane-electrode assembly.

4. In Paragraph 3, The first compound comprises a compound represented by the following chemical formula 1, a compound represented by the following chemical formula 2, or a combination thereof. Membrane-electrode assembly: [Chemical Formula 1] In Chemical Formula 1, R 11 to R 15 is each independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and R 11 to R 15 At least two of them are hydroxyl groups, and [Chemical Formula 2] In Chemical Formula 2, R 21 to R 26 is each independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and R 21 to R 26 At least two of them are hydroxyl groups.

5. In Paragraph 3, The second compound above comprises a compound represented by Chemical Formula 3 below, a compound represented by Chemical Formula 4 below, or a combination thereof. Membrane-electrode assembly: [Chemical Formula 3] In Chemical Formula 3, R 31 to R 35 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and R 31 to R 35 At least two of them are hydroxyl groups, and R 31 to R 35 At least one of them is a carboxyl group, or a substituted or unsubstituted alkylene carboxyl group, and [Chemical Formula 4] In Chemical Formula 4, R 41 to R 46 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and R 41 to R 46 At least two of them are hydroxyl groups, and at least one is a carboxyl group, or a substituted or unsubstituted alkylene carboxyl group.

6. In Paragraph 3, The above third compound comprises a compound represented by Chemical Formula 5 below, a compound represented by Chemical Formula 6 below, or a combination thereof. Membrane-electrode assembly: [Chemical Formula 5] In Chemical Formula 5, R 51 to R 56 Each is independently a hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and X 51 To X 54 Each is independently an oxygen atom (O) or a sulfur atom (S), and R 51 to R 53 At least two of them are hydroxyl groups, and R 54 to R 56 At least two of them are hydroxyl groups, and [Chemical Formula 6] In chemical formula 6, R 611 to R 614 , and R 619 to R 623 is each independently hydrogen, a substituted or unsubstituted alkyl group, or a hydroxyl group, and R 615 to R 618 Each is independently a hydrogen, hydroxyl group, carboxyl group, substituted or unsubstituted alkylene carboxyl group, or aldehyde group, X6 is an oxygen atom (O) or a sulfur atom (S), and R 611 to R 614 At least two of them are hydroxyl groups, and R 619 to R 623 At least two of them are hydroxyl groups.

7. In Paragraph 3, The above-mentioned fourth compound comprises a compound represented by the following chemical formula 7, a compound represented by the following chemical formula 8, or a combination thereof. Membrane-electrode assembly: [Chemical Formula 7] In Chemical Formula 7, R 711 to R 726 is each independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and Z7 is an ester bond, a substituted or unsubstituted alkylene ester bond, or a substituted or unsubstituted alkenylene ester bond, and R 711 to R 721 At least two of them are hydroxyl groups, at least one is a carboxyl group, and R 722 to R 726 At least two of them are hydroxyl groups, and at least one is a carboxyl group or a substituted or unsubstituted alkylene carboxyl group, and [Chemical Formula 8] In chemical formula 8, R 811 to R 820 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, an aldehyde group, a carbonyl group, or a substituent represented by the chemical formulas 8-1 to 8-2 below, X8 is an oxygen atom (O) or a sulfur atom (S), and R 811 to R 820 At least two of them are substituents represented by chemical formulas 8-1 to 8-2, and R 811 to R 820 At least two of them are hydroxyl groups, and [Chemical Formula 8-1] In chemical formula 8-1, R 8111 to R 8115 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and Z 81 is an ester bond, a substituted or unsubstituted alkylene ester bond, or a substituted or unsubstituted alkenylene ester bond, and R 8111 to R 8115 At least two of them are hydroxyl groups, and [Chemical Formula 8-2] In chemical formula 8-2, R 8211 to R 8219 Each is independently hydrogen, a substituted or unsubstituted alkyl group, a hydroxyl group, a carboxyl group, a substituted or unsubstituted alkylene carboxyl group, or an aldehyde group, and Z 82 To Z 83 Each is independently an ester bond, a substituted or unsubstituted alkylene ester bond, or a substituted or unsubstituted alkenylene ester bond, and R 8211 to R 8219 At least 4 of them are hydroxyl groups.

8. In Paragraph 1, The above polyphenol compound includes pyrogallol, caffeic acid, gallic acid, ellagic acid, catechin, chlorogenic acid, tannic acid, or a combination thereof. Membrane-electrode assembly.

9. In Paragraph 1, The first ion conductor comprises a fluorine-based ion conductor, a hydrocarbon-based ion conductor, or a combination thereof. Membrane-electrode assembly.

10. In Paragraph 1, The above polyphenol compound is included in an amount of 0.3 to 15 parts by weight per 100 parts by weight of the first ion conductor, and The first ion conductor is included in an amount of 68% to 99.6% by weight with respect to 100% by weight of the bonding layer, Membrane-electrode assembly.

11. In Paragraph 1, The bonding layer comprises: pores (surface recesses) formed on the surface of the first electrode, the second electrode, or both thereof; pores existing at a certain depth from the surface of the first electrode, the second electrode, or both thereof; or a combination thereof, filling Membrane-electrode assembly.

12. In Paragraph 1, The thickness of the bonding layer is 0.01 μm to 10 μm, and The mass per unit area of ​​the above bonding layer is 0.01 mg / cm² 2 to 2.0 mg / cm² 2 person, Membrane-electrode assembly.

13. In Paragraph 1, The above bonding layer further comprises nano powder, and The above nanopowder is in the form of particles, having an average particle size of 1 nm to 50 nm, Membrane-electrode assembly.

14. In Paragraph 13, The above nanopowder comprises a hydrophilic inorganic material, a radical scavenger, a catalyst for an oxygen evolution reaction (OER), or a combination thereof. Membrane-electrode assembly.

15. In Paragraph 14, The above hydrophilic inorganic material comprises SnO2 (tin oxide), fumed silica, clay, alumina, mica, zeolite, phosphotungstic acid, silicon tungstic acid, zirconium hydrogen phosphate, or a mixture thereof. The above radical scavenger comprises cerium, ruthenium, palladium, silver, rhodium, yttrium, manganese, molybdenum, lead, vanadium, titanium, their ionic forms, their oxide forms, their salt forms, or mixtures thereof, and The above-mentioned catalyst for the oxygen evolution reaction comprises platinum, gold, palladium, rhodium, iridium, ruthenium, osmium, platinum alloys, alloys thereof, or mixtures thereof. Membrane-electrode assembly.

16. In Paragraph 13, In the bonding layer, the nano powder is included in an amount of 0.1 to 30 parts by weight per 100 parts by weight of the first ion conductor. Membrane-electrode assembly.

17. A step of forming a bonding layer by applying a composition for forming a bonding layer onto a first electrode where an oxidation reaction occurs, a second electrode where a reduction reaction occurs, or both electrodes; A step of bonding a polymer electrolyte membrane to a first electrode having a bonding layer, a second electrode having a bonding layer, or both electrodes having a bonding layer; The above polymer electrolyte membrane is located between the first electrode and the second electrode, and The above bonding layer comprises a polyphenol compound and a first ion conductor, Method for manufacturing a membrane-electrode assembly.

18. In Paragraph 17, The above bonding layer is formed by spray coating the composition for forming the bonding layer onto the first electrode, the second electrode, or both electrodes. Method for manufacturing a membrane-electrode assembly.

19. A membrane-electrode assembly comprising the membrane-electrode assembly according to claim 1, Electrochemical cell.

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