Composition for forming electrode, electrode, membrane-electrode assembly, manufacturing method therefor, and electrochemical cell

Abstract

The present disclosure relates to a composition for forming an electrode, an electrode, a membrane-electrode assembly, a manufacturing method therefor, and an electrochemical cell. More specifically, by including a plasticizer having an aromatic carboxylate substituent in the electrode, the membrane-electrode assembly: strengthens the bonding between the catalyst and the ion conductor in the electrode and improves the flexibility and elasticity of the ion conductor, thereby enhancing the performance and durability of the electrochemical cell; and, even when the electrode or polymer electrolyte membrane contains a hydrocarbon-based ion conductor, improves ion conductivity of the hydrocarbon-based ion conductor and lowers the glass transition temperature thereof, thereby facilitating the transfer process used to form the membrane-electrode assembly.

Description

Composition for forming electrodes, electrode, membrane-electrode assembly, method of manufacturing the same, and electrochemical cell

[0001] The present disclosure relates to a composition for forming an electrode, an electrode, a membrane-electrode assembly, a method for manufacturing the same, and an electrochemical cell. More specifically, by including a plasticizer comprising an aromatic carboxylate substituent in the composition for forming the electrode, the bonding between the catalyst and the ion conductor within the electrode is strengthened, and the flexibility and elasticity of the ion conductor are improved, thereby improving the performance and durability of the electrochemical cell. Furthermore, even when the electrode includes a hydrocarbon-based ion conductor or a polymer electrolyte membrane, the ion conductivity of the hydrocarbon-based ion conductor is improved and the glass transition temperature is lowered, thereby facilitating the transfer process for forming the membrane-electrode assembly.

[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, electrodes consist of a porous structure in which an ion conductor is mixed with a catalyst and a binder. Due to the weak bonding between the catalyst and the ion conductor, irreversible changes may occur during system operation, leading to a decrease in performance and durability.

[0007] In addition, when a transfer process is performed under high temperature and high pressure conditions to manufacture membrane-electrode assemblies, if the electrode or polymer electrolyte membrane contains a hydrocarbon-based ion conductor, the glass transition temperature is high, which can reduce transferability and consequently cause electrode detachment and severe degradation of durability.

[0008] According to one embodiment, by including a plasticizer comprising an aromatic carboxylate substituent, a composition for forming an electrode and an electrode can be provided in which the bonding between the catalyst and the ion conductor within the electrode is strengthened, and a membrane-electrode assembly and an electrochemical cell can be provided in which the flexibility and elasticity of the ion conductor are improved due to the plasticizer included in the electrode, thereby improving performance and durability.

[0009] According to another embodiment, a method for manufacturing a membrane-electrode assembly is provided in which the ionic conductivity of the hydrocarbon ion conductor is improved and the glass transition temperature is lowered due to the aforementioned plasticizer, thereby facilitating a transfer process, even when the electrode or polymer electrolyte membrane comprises a hydrocarbon ion conductor.

[0010] One embodiment provides a composition for forming an electrode comprising: a first catalyst; a first ion conductor; and a plasticizer comprising an aromatic carboxylate substituent.

[0011] Another embodiment provides an electrode comprising: a first catalyst; a first ion conductor; and a plasticizer comprising an aromatic carboxylate substituent.

[0012] Another embodiment provides a membrane-electrode assembly comprising a first electrode where an oxidation reaction takes place, a second electrode where a reduction reaction takes place, and a polymer electrolyte membrane located between the first electrode and the second electrode, wherein the first electrode, the second electrode, or both are the aforementioned electrodes.

[0013] Another embodiment provides a method for manufacturing a membrane-electrode assembly comprising the steps of: manufacturing a composition for forming an electrode as described above; manufacturing an electrode using the composition for forming an electrode; and manufacturing a membrane-electrode assembly using the electrode, wherein the manufactured electrode is a first electrode in which an oxidation reaction occurs, a second electrode in which a reduction reaction occurs, or an electrode for both.

[0014] Another embodiment provides an electrochemical cell comprising the aforementioned membrane-electrode assembly.

[0015] A composition for forming an electrode according to one embodiment includes a plasticizer comprising an aromatic carboxylate substituent, thereby strengthening the bonding between the catalyst and the ion conductor within the electrode and improving the flexibility and elasticity of the ion conductor, which can improve the performance and durability of the electrochemical cell. In the case of an electrode or polymer electrolyte membrane containing a hydrocarbon-based ion conductor, the ion conductivity of the hydrocarbon-based ion conductor is improved and the glass transition temperature is lowered, which can facilitate the transfer process for forming a membrane-electrode assembly.

[0016] FIG. 1 is a schematic diagram showing a membrane-electrode assembly (MEA) according to one embodiment.

[0017] Figure 2 is a photograph showing the results of the hydrothermal evaluation of the membrane-electrode assembly for a fuel cell prepared in Example 1-2.

[0018] Figure 3 is a photograph showing the results of the hydrothermal evaluation of the membrane-electrode assembly for a fuel cell manufactured in Comparative Example 1.

[0019] Figure 4 is a photograph showing the results of evaluating the bonding strength between the electrode and the polymer electrolyte membrane of the membrane-electrode assembly for a fuel cell prepared in Example 1-2.

[0020] Figure 5 is a photograph showing the results of evaluating the bonding strength between the electrode and the polymer electrolyte membrane of the membrane-electrode assembly for a fuel cell prepared in Comparative Example 1.

[0021] 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.

[0022] In this specification, "combination thereof" means a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, a reaction product, etc.

[0023] 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.

[0024] 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.

[0025] "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.

[0026] 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.

[0027] "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.

[0028] 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.

[0029] "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.

[0030] 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.

[0031] "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).

[0032] 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.

[0033] "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.

[0034] "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.

[0035] "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.

[0036] In this specification, * at both ends of a chemical formula indicates that it is connected to an adjacent chemical formula.

[0037] composition for forming electrodes

[0038] In one embodiment, a composition for forming an electrode is provided, comprising: a first catalyst; a first ion conductor; and a plasticizer comprising an aromatic carboxylate substituent. The composition for forming an electrode may be a composition for forming an electrode of an electrochemical cell.

[0039] Generally, a composition for forming an electrode includes a catalyst and an ion conductor. Among these, the ion conductor may undergo irreversible changes during operation due to weak bonding with the catalyst, which can lead to a decrease in performance and durability. To prevent this, one embodiment further includes a plasticizer comprising an aromatic carboxylate substituent.

[0040] The above aromatic carboxylate substituent has a carboxylate group (-COO) on an aromatic ring. - It has a structure in which ) is combined, and other substituents can be additionally combined to the above ring.

[0041] For example, the above aromatic carboxylate substituent may include a dibenzoate group. The dibenzoate group is a type of benzoic acid ester and has a structure in which two benzoic acids are linked via an alcohol, specifically having a structure in which two molecules of benzoic acid are connected to an alcohol through an ester bond.

[0042] For example, a plasticizer containing the above aromatic carboxylate substituent may include a compound represented by the following chemical formula 1.

[0043] [Chemical Formula 1]

[0044]

[0045] In the above Chemical Formula 1, X comprises a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted arylene group, or an ether group represented by the following Chemical Formula 2. When the alkylene group, cycloalkylene group, and arylene group are each independently substituted, they may be substituted with an alkyl group having 1 to 10 carbon atoms or a halogen group.

[0046] [Chemical Formula 2]

[0047]

[0048] In the above chemical formula 2, Z1 and Z2 are each independently a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group, and n is an integer from 1 to 4. When the alkylene group, cycloalkylene group, and arylene group are each independently substituted, they may be substituted with an alkyl group having 1 to 10 carbon atoms or a halogen group.

[0049] For example, in the above formula 1, X may include a substituted or unsubstituted alkylene group. In the above formula 1, X may be an unsubstituted alkylene group, for example, an alkylene group having 2 to 10 carbon atoms, an alkylene group having 2 to 8 carbon atoms, or an alkylene group having 2 to 6 carbon atoms.

[0050] As another example, in the above formula 1, X may include an ether group represented by formula 2. In the above formula 2, Z1 and Z2 may each independently be substituted or unsubstituted alkylene groups, and more specifically, unsubstituted alkylene groups. For example, Z1 and Z2 may be alkylene groups having 2 to 10 carbon atoms, alkylene groups having 2 to 8 carbon atoms, alkylene groups having 2 to 5 carbon atoms, or alkylene groups having 2 to 3 carbon atoms. Also, in the above formula 2, n may be 1.

[0051] Plasticizers containing the above aromatic carboxylate substituents may include dipropylene glycol dibenzoate (DPGDB), diethylene glycol dibenzoate (DEGDB), 1,3-propanediyl dibenzoate, 1,4-butanediyl dibenzoate, 1,5-pentanediyl dibenzoate, 1,6-hexanediyl dibenzoate, or combinations thereof.

[0052] The plasticizer containing the aromatic carboxylate substituent may be included in an amount of 0.1% to 20% by weight based on 100% by weight of the electrode-forming composition, or in an amount of 0.3% to 15% by weight, 0.5% to 10% by weight, 0.7% to 8% by weight, 1% to 7% by weight, or 2% to 6% by weight. When the content of the plasticizer in the electrode-forming composition satisfies the above range, it is possible to improve ion conductivity by increasing the mobility of the ion conductor along with improving the adhesion between the membrane-electrode assembly materials.

[0053] The above catalyst may include a precious metal or a precious metal oxide.

[0054] The above precious metal may be a platinum-based precious metal.

[0055] 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).

[0056] 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.

[0057] The above precious metal oxide may be iridium oxide, an oxide of an iridium alloy, or a combination thereof.

[0058] For example, the above precious metal oxide is IrO x (The above x is an integer from 1 to 3), IrMO x (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.

[0059] 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 between the carrier supporting the precious metal and the carrier supporting the precious metal oxide, respectively.

[0060] The first carrier above may be a carbon-based carrier.

[0061] 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.

[0062] The second carrier may be a metal oxide.

[0063] The metal oxide may be tungsten oxide, titanium oxide, nickel oxide, ruthenium oxide, tantalum oxide, tin oxide, cobalt oxide, or a combination thereof.

[0064] The catalyst may be included in an amount of 1% to 40% by weight with respect to 100% by weight of the electrode-forming composition, 2% to 30% by weight, 3% to 20% by weight, or 5% to 15% by weight. When the content of the catalyst in the electrode-forming composition satisfies the above range, it may help maintain the dispersion stability of the electrode-forming composition and form a stable coating in a subsequent coating process.

[0065] The first ion conductor can perform a role in improving adhesion within the electrode and ion transfer.

[0066] The first ion conductor may include a fluorine-based ion conductor, a hydrocarbon-based ion conductor, and a combination thereof, and the first ion conductor may have a cation exchanger or an anion exchanger.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] The first ion conductor may be included in an amount of 1% to 40% by weight relative to 100% by weight of the electrode-forming composition, or in an amount of 5% to 38% by weight, 10% to 36% by weight, 15% to 34% by weight, or 20% to 30% by weight. When the content of the first ion conductor satisfies the above range, the first ion conductor appropriately performs the roles of a dispersant and a binding agent during the preparation of the electrode-forming composition, thereby allowing for improved dispersibility. Furthermore, when the first ion conductor is included in an excessive amount outside the above range, it may result in a loss of the catalytic active surface area and blockage of gas supply into the electrode layer; however, this can be avoided.

[0074] The first ion conductor can be used in the form of a single substance or a mixture, and may also be optionally used with a non-conductive compound to further improve adhesion to the polymer electrolyte membrane. The content of the non-conductive compound can be appropriately adjusted according to the intended use.

[0075] 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.

[0076] The above electrode-forming composition may further include a solvent in addition to a catalyst, a first ion conductor, and a plasticizer containing an aromatic carboxylate substituent.

[0077] The above solvent may include water, methanol, ethanol, butanol, n-propanol, isopropanol, n-butyl acetate, ethylene glycol, dipropylene glycol, glycerol, or a combination thereof. The type of solvent is not limited as long as it is included in the electrode-forming composition and can effectively disperse the catalyst.

[0078] The content of the solvent may be the remainder after excluding the sum of the contents of the catalyst, the first ion conductor, and the plasticizer containing the aromatic carboxylate substituent in the electrode-forming composition.

[0079] electrode

[0080] In another embodiment, an electrode is provided comprising: a first catalyst; a first ion conductor; and a plasticizer comprising an aromatic carboxylate substituent.

[0081] The details regarding the first catalyst, the first ion conductor, and the plasticizer are as described above.

[0082] The electrode may be manufactured using the aforementioned electrode-forming composition. For example, the electrode may be manufactured by applying the electrode-forming composition to a release film and drying it, or by applying the electrode-forming composition to a polymer electrolyte membrane and drying it. Specific details regarding the method of manufacturing the electrode using the electrode-forming composition are described below. In this case, the solvent contained in the electrode-forming composition may be mostly volatilized and removed during the drying process, while a portion of the plasticizer containing the aromatic carboxylate substituent may remain in the electrode without volatilizing. That is, the plasticizer may be present in a small amount in the finally produced electrode.

[0083] The catalyst may be included in an amount of 50% to 95% by weight relative to 100% by weight of the electrode, or in an amount of 55% to 90% by weight. When the catalyst is included in the electrode within the above range, the performance is excellent, and the efficiency is excellent as fuel supply is smooth. For example, if the catalyst content in the electrode is included in an excessively small amount compared to the above range, the resistance in the membrane-electrode assembly increases, which may degrade performance; and if it is included in an excessively large amount compared to the above range, ion transfer to the catalyst is insufficient, which may degrade performance, or the bonding between catalyst particles is weakened, which may weaken durability.

[0084] For example, the plasticizer containing the aromatic carboxylate substituent may be included in an amount of 10% by weight or less, 8% by weight or less, 6% by weight or less, or 5% by weight or less with respect to 100% by weight of the electrode.

[0085] The above electrode can enhance the bonding between the ion conductor and the catalyst within the electrode by including a plasticizer comprising the aforementioned aromatic carboxylate substituent, which is environmentally friendly and possesses excellent compatibility with the ion conductor, low volatility, migration resistance, and thermal stability.

[0086] The above electrode may comprise only a catalyst layer comprising the aforementioned catalyst; an ion conductor; and a plasticizer comprising an aromatic carboxylate substituent; or may further comprise an electrode substrate together with the catalyst layer.

[0087] At this time, the electrode substrate can perform the role of supporting the electrode while diffusing fuel and oxidant into the catalyst layer.

[0088] The electrode substrate may include a micropore layer, a porous diffusion layer, or a combination thereof.

[0089] 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.

[0090] 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).

[0091] The micropore layer and the porous diffusion layer may include known types in addition to those exemplified above.

[0092] Membrane-electrode assembly

[0093] In another embodiment, a membrane-electrode assembly is provided comprising a first electrode where an oxidation reaction occurs, a second electrode where a reduction reaction occurs, and a polymer electrolyte membrane located between the first electrode and the second electrode, wherein the first electrode, the second electrode, or both are the aforementioned electrodes.

[0094] The above membrane-electrode assembly can typically be applied to an electrochemical cell, for example, a fuel cell or a water electrolysis cell.

[0095] 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.

[0096] FIG. 1 is a schematic diagram showing a membrane-electrode assembly according to one embodiment.

[0097] Referring to FIG. 1, the membrane-electrode assembly (100) includes a first electrode (10), a second electrode (20), and a polymer electrolyte membrane (30) located between the first electrode (10) and the second electrode (20). Details regarding the first electrode, the second electrode, and the polymer electrolyte membrane are described below.

[0098] First electrode and second electrode

[0099] 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 (more specifically, the oxygen generation electrode). For convenience, the first and second electrodes 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 including 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 and second electrodes based on the electrode where the oxidation reaction occurs and the electrode where the reduction reaction occurs. The first electrode may be called the anode in an electrochemical cell.

[0100] [Reaction Equation 1-1]

[0101] H2→ 2H + + 2e-

[0102] [Reaction Equation 2-1]

[0103] 2H2O → O2 + 4H + + 4e -

[0104] 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 (more specifically, the hydrogen generation electrode). The second electrode can be called the cathode in an electrochemical cell.

[0105] [Reaction Equation 1-2]

[0106] O2+ 4H + + 4e - → 2H2O

[0107] [Reaction Equation 2-2]

[0108] 2H + + 2e - → H2

[0109] The first electrode, the second electrode, or both may be the electrodes described above. Specific details regarding the electrodes are as described above and are therefore omitted below.

[0110] The first electrode, the second electrode, or both may include a first ion conductor as described above. Since the details regarding the first ion conductor are as described above, they will be omitted below.

[0111] polymer electrolyte membrane

[0112] 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.

[0113] The above polymer electrolyte membrane may include a second ion conductor.

[0114] The type of second ion conductor included in the above polymer electrolyte membrane is as described above regarding the first ion conductor.

[0115] The second ion conductor included in the polymer electrolyte membrane and the first ion conductor included in the first electrode or the second electrode may be the same or different from each other.

[0116] A membrane-electrode assembly comprising an electrode containing the aforementioned plasticizer can enhance performance and durability by strengthening the bonding between the catalyst and the ion conductor within the electrode and improving the flexibility and elasticity of the ion conductor, regardless of the type of ion conductor. For example, the first ion conductor and the second ion conductor may be identical and both may include fluorine-based ion conductors. In this case, although the problem of reduced transferability due to the high glass transition temperature of the hydrocarbon-based ion conductor described later does not occur, problems regarding reduced performance and durability may arise due to irreversible changes during system operation caused by the weak bonding between the catalyst and the ion conductor within the electrode; however, this problem can be solved by including the aforementioned plasticizer within the electrode.

[0117] At least one of the first ion conductor and the second ion conductor may include a hydrocarbon-based ion conductor. In this case, by including the aforementioned plasticizer within the electrode, the problem of reduced transferability due to the high glass transition temperature of the hydrocarbon-based ion conductor is resolved, and the ion conductivity of the hydrocarbon-based ion conductor is improved and the glass transition temperature is lowered, thereby facilitating the transfer process. For example, either only one of the first ion conductor and the second ion conductor may include a hydrocarbon-based ion conductor, or both the first ion conductor and the second ion conductor may include hydrocarbon-based ion conductors. In this case, the bonding between the catalyst and the ion conductor within the electrode is strengthened, and the flexibility and elasticity of the ion conductor are improved, thereby enhancing performance and durability. Furthermore, even though the hydrocarbon-based ion conductor has a high glass transition temperature, the ion conductivity of the hydrocarbon-based ion conductor is improved and the glass transition temperature is lowered due to the plasticizer, thereby facilitating the transfer process.

[0118] However, the membrane-electrode assembly according to one embodiment includes a plasticizer containing an aromatic carboxylate substituent within the electrode, thereby not only strengthening the bonding between the catalyst and the ion conductor within the electrode but also improving the adhesion strength and stability between the electrode and the polymer electrolyte membrane, so as not to cause the above problem.

[0119] 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.

[0120] The above porous support may be a fluorine-based support, a nanoweb support, or a combination thereof.

[0121] 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.

[0122] 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.

[0123] Method for manufacturing a membrane-electrode assembly

[0124] In another embodiment, a method for manufacturing a membrane-electrode assembly is provided, comprising the steps of: manufacturing the aforementioned electrode-forming composition; manufacturing an electrode using the electrode-forming composition; and manufacturing a membrane-electrode assembly using the electrode. The manufactured electrode is a first electrode in which an oxidation reaction occurs, a second electrode in which a reduction reaction occurs, or an electrode for both.

[0125] First, a composition for forming an electrode is prepared.

[0126] The components included in the above electrode forming composition are as described above.

[0127] In the step of preparing the above electrode-forming composition, the electrode-forming composition can be prepared by adding a catalyst, an ion conductor, and a plasticizer comprising an aromatic carboxylate substituent to a solvent, mixing, and dispersing. The mixing and dispersing step can be performed using an ultrasonic grinder, a homomixer, a 3-roll mill, a resonant acoustic mixer, a paste mixer, a stirrer, a high-shear disperser, a homogenizing mixer, or a combination thereof.

[0128] Next, an electrode is manufactured using the electrode-forming composition. The method of manufacturing the electrode is not specifically limited as long as it utilizes the electrode-forming composition.

[0129] For example, the step of manufacturing the electrode may be performed by applying the electrode-forming composition to a release film and drying it, or by applying the electrode-forming composition to a polymer electrolyte membrane and drying it. In the former case, an electrode can be formed on the release film, and a membrane-electrode assembly can be manufactured through a process of transferring it to the polymer electrolyte membrane as described below. In the latter case, the electrode can be formed by directly applying the electrode-forming composition to the polymer electrolyte membrane, thereby eliminating the need for a separate transfer process, unlike in the former case. The release film may be any known materials without limitation. Although the electrode can be manufactured according to the former process, direct application to the membrane is disadvantageous for mass production purposes, so the electrode may be manufactured according to the latter method. In this case, while this does not occur when using a fluorine-based ion conductor, when using a hydrocarbon-based ion conductor, a problem may arise where transfer is not easy due to the high glass transition temperature. However, by including the aforementioned plasticizer, when using a fluorine-based ion conductor, not only is performance and durability improved, but even when using a hydrocarbon-based ion conductor, the transfer process is facilitated along with the above effects, making it suitable for mass production.

[0130] Depending on the viscosity of the electrode forming composition, the coating process described above may use screen printing, spray coating, coating using a doctor blade, coating using a slot die, etc., but is not limited thereto.

[0131] The above electrode forming composition may be applied to a thickness of 10㎛ to 200㎛, but is not limited thereto.

[0132] The above electrode-forming composition may be applied to a release film or a polymer electrolyte membrane, and then a drying process may be performed. During the drying process, the solvent may be removed by evaporation. For example, the drying may be performed at 25°C to 90°C for 8 hours or more. For example, the drying may be performed at 30°C to 85°C, 40°C to 80°C, or 50°C to 70°C for 8 hours or more. The drying temperature and time may vary depending on the composition of the solvent in the electrode-forming composition or the application method prior to drying, and are therefore not limited to the above conditions.

[0133] Next, a membrane-electrode assembly is manufactured using the above electrode.

[0134] The step of manufacturing the above membrane-electrode assembly may be to manufacture the electrode by applying heat and pressure to at least one surface of the polymer electrolyte membrane to transfer it, or to manufacture the electrode by forming it on the other surface of the polymer electrolyte membrane where the electrode is not located, using an electrode-forming composition.

[0135] As described above, when an electrode is formed by applying an electrode-forming composition to a release film and drying it during electrode manufacturing, a separate process for transferring the manufactured electrode to a polymer electrolyte membrane may be required. In such cases, a membrane-electrode assembly can be manufactured according to the former method among membrane-electrode assembly manufacturing methods.

[0136] That is, when the step of manufacturing a membrane-electrode assembly including the electrode is performed by transferring the electrode to at least one surface of a polymer electrolyte membrane by applying heat and pressure, the heat may be applied at a temperature of 80°C to 200°C, and for example, at a temperature of 100°C to 200°C, 120°C to 200°C, or 140°C to 200°C. In addition, the pressure is 5 kgf / cm² 2 Up to 200 kgf / cm² 2It can be performed at a pressure of, for example, 5 kgf / cm² 2 Up to 100 kgf / cm² 2 , 5 kgf / cm 2 Up to 50 kgf / cm² 2 , or 7 kgf / cm² 2 Up to 30 kgf / cm² 2 It can be performed at a pressure of . If the heat and pressure in the above transfer process satisfy the above range, changes in the electrode structure caused by the high temperature and high pressure transfer process can be minimized. The pressure is 5 kgf / cm² 2 If it is less than, the transfer to the electrode layer film may not be fully achieved, and the pressure is 200 kgf / cm² 2 If exceeded, the electrode layer structure may be destroyed, leading to performance degradation due to increased mass transfer resistance.

[0137] Meanwhile, as described above, when an electrode is formed by directly applying an electrode-forming composition to a polymer electrolyte membrane and drying it during electrode manufacturing, a separate transfer process may not be required, unlike the method of manufacturing an electrode by applying it to a release film where the electrode is formed on the polymer electrolyte membrane. In this case, an electrode may be formed on the other side of the polymer electrolyte membrane where the electrode is not formed using the electrode-forming composition, or a commercially available electrode may be obtained and formed on the other side of the polymer electrolyte membrane. When manufacturing a membrane-electrode assembly according to the above method, it may be manufactured according to a known method.

[0138] According to a method for manufacturing a membrane-electrode assembly according to one embodiment, a plasticizer comprising an aromatic carboxylate substituent in the electrode is included in the electrode-forming composition to strengthen the bonding force between the catalyst and the ion conductor in the electrode, and to improve the bonding force and stability between the electrode and the polymer electrolyte membrane, thereby improving performance and durability. Even when a hydrocarbon ion conductor is included in at least one of the polymer electrolyte membrane and the electrode, the ion conductivity of the hydrocarbon ion conductor can be improved due to the plasticizer, and the transfer process can be facilitated by lowering the glass transition temperature of the hydrocarbon ion conductor. Furthermore, bonding force and retention force can be improved through post-curing and crosslinking of the plasticizer during the transfer process performed at high temperature and high pressure.

[0139] electrochemical cell

[0140] 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.

[0141] 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.

[0142] (Fuel cell)

[0143] Example 1-1

[0144] An electrode forming composition was prepared by adding 5g of Pt / C (Tanaka, TEC10E50E) as a catalyst, 10g of Nafion D2021 (Dupont) as an ion conductor, 2g of dipropylene glycol dibenzoate (DPGDB) represented by the chemical formula A below as a plasticizer, and 25g of a mixture of dipropylene glycol and distilled water in a weight ratio of 1:1 (=dipropylene glycol:distilled water) as a solvent, and dispersing them using a 3-roll mill (EXAKT 50). In 100 wt% of the electrode forming composition, the content of the catalyst was 11.9 wt%, the content of the ion conductor was 23.8 wt%, and the content of the plasticizer was 4.76 wt%.

[0145] 0.1 mg Pt / cm² of the above electrode-forming composition on the first surface of a Teflon release film 2 , on the second surface facing the first surface above, 0.4 mg Pt / cm 2 After applying with 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 8 hours.

[0146] A hydrocarbon-based polymer electrolyte membrane is interposed between the first electrode and the second electrode, and at 160°C and 20 kgf / cm² 2 A membrane-electrode assembly for a fuel cell, in which the first electrode and the second electrode are bonded to a hydrocarbon-based polymer electrolyte membrane, was manufactured by applying heat and pressure for 3 minutes under certain conditions and then peeling off a Teflon release film. The content of the plasticizer was about 2 wt% with respect to 100 wt% of the first electrode, and the content of the plasticizer was about 5 wt% with respect to 100 wt% of the second electrode.

[0147] [Chemical Formula A]

[0148]

[0149]

[0150] Examples 1-2

[0151] A membrane-electrode assembly for a fuel cell was prepared in substantially the same manner as in Example 1-1, except that 1g of the plasticizer was mixed instead of 2g of the plasticizer mixed in Example 1-1. In 100 wt% of the electrode-forming composition, the content of the catalyst was 12.2 wt%, the content of the ion conductor was 24.4 wt%, and the content of the plasticizer was 2.44 wt%.

[0152]

[0153] Examples 1-3

[0154] A membrane-electrode assembly for a fuel cell was prepared substantially identically to Example 1-1, except that in Example 1-1, diethylene glycol dibenzoate (DEGDB) represented by the following chemical formula B was used as the plasticizer instead of dipropylene glycol dibenzoate (DPGDB) represented by chemical formula A. In 100 wt% of the electrode-forming composition, the content of the catalyst was 11.9 wt%, the content of the ion conductor was 23.81 wt%, and the content of the plasticizer was 4.76 wt%.

[0155] [Chemical Formula B]

[0156]

[0157]

[0158] Comparative Example 1

[0159] A membrane-electrode assembly for a fuel cell was manufactured substantially identically to Example 1-1, except that the first electrode and the second electrode were manufactured using an electrode-forming composition without the addition of a plasticizer in Example 1-1.

[0160]

[0161] (Electrolytic cell)

[0162] Example 2-1

[0163] IrO as a catalyst for oxygen evolution reaction xA composition for forming a first electrode was prepared by adding 5g of / TiO2 (Alfa Aesar, 43396), 12.5g of Nafion D2021 (Dupont) as an ion conductor, 2.5g of dipropylene glycol dibenzoate (DPGDB) represented by the chemical formula A below as a plasticizer, and 25g of a mixture of water and n-propanol in a weight ratio of 4:6 (=water:n-propanol) as a solvent, and dispersing them using a homogenizer. In 100 wt% of the composition for forming a first electrode, the content of the catalyst was 11.11 wt%, the content of the ion conductor was 27.78 wt%, and the content of the plasticizer was 5.56 wt%.

[0164] A second electrode composition was prepared by adding 5g of Pt / C (Tanaka, TEC10E50E) as a catalyst for hydrogen generation reaction, 10g of Nafion D2021 (Dupont) as an ion conductor, 2g of dipropylene glycol dibenzoate (DPGDB) represented by the chemical formula A below as a plasticizer, and 25g of a mixture of water and n-propanol in a weight ratio of 4:6 (=water:n-propanol) as a solvent, and dispersing them using a homogenizer. In 100 wt% of the composition for forming the second electrode, the content of the catalyst was 11.9 wt%, the content of the ion conductor was 23.81 wt%, and the content of the plasticizer was 4.76 wt%.

[0165] 1.0 mg / cm² of the above-mentioned first electrode-forming composition on the first surface of a polyimide film of PI Advanced Materials Co., Ltd. having a thickness of 150 μm as a release film 2 , the above second electrode forming composition is applied to the second surface facing the first surface at a concentration of 0.2 mg / cm 2 After applying with a doctor blade to achieve the desired result, the first electrode (oxygen generating electrode) was prepared on the first surface and the second electrode (hydrogen generating electrode) was prepared on the second surface by drying at 60°C for 8 hours.

[0166] 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 in which the first electrode and the second electrode are bonded to a polymer electrolyte membrane was prepared by applying heat and pressure for 3 minutes under the conditions and then peeling off the polyimide film. The content of the plasticizer was about 5 wt% with respect to 100 wt% of the first electrode, and the content of the plasticizer was about 1 wt% with respect to 100 wt% of the second electrode.

[0167] [Chemical Formula A]

[0168]

[0169]

[0170] Example 2-2

[0171] A membrane-electrode assembly for a water electrolysis cell was prepared in substantially the same manner as in Example 2-1, except that a hydrocarbon-based polymer electrolyte membrane was used instead of a fluorine-based polymer electrolyte membrane in Example 2-1.

[0172]

[0173] Comparative Example 2

[0174] A membrane-electrode assembly for a water electrolysis cell was manufactured in substantially the same manner as in Example 2, except that the first electrode (oxygen generating electrode) and the second electrode (hydrogen generating electrode) were manufactured using the first electrode forming composition and the second electrode forming composition without the addition of a plasticizer in Example 2-1 above.

[0175]

[0176] Evaluation example

[0177] (Membrane-electrode assembly for fuel cells)

[0178] 1. Hydrothermal Evaluation of Membrane-Electrode Assembly

[0179] The hydrothermal evaluation of the membrane-electrode assemblies for fuel cells prepared in Examples 1-1 to 1-3 and Comparative Example 1 above was evaluated as follows.

[0180] Water was placed in a beaker using a hot plate and heated until it reached a temperature of 100°C. When the water boiled, the prepared membrane-electrode assembly was introduced, and after 6 hours, separation between the polymer electrolyte membrane and the electrode was observed.

[0181] The results are shown in Figures 2 and 3 below. Figure 2 is a photograph showing the results of the hydrothermal evaluation of the membrane-electrode assembly for a fuel cell prepared in Examples 1-2, and Figure 3 is a photograph showing the results of the hydrothermal evaluation of the membrane-electrode assembly for a fuel cell prepared in Comparative Example 1.

[0182] Referring to FIGS. 2 and 3, in the case of Example 1-2, in which a composition for forming an electrode is prepared including a plasticizer containing an aromatic carboxylate substituent and a membrane-electrode assembly is prepared including an electrode prepared using the same and a polymer electrolyte membrane containing a hydrocarbon ion conductor, it can be confirmed that the transfer process is easily performed due to the plasticizer even though a hydrocarbon ion conductor is included, and the electrode remains well bonded even after the polymer electrolyte membrane is broken following a hydrothermal evaluation. However, in the case of Comparative Example 1, in which this is not the case, it can be confirmed that the electrode separates after the polymer electrolyte membrane is broken.

[0183]

[0184] 2. Evaluation of adhesion between electrode and polymer electrolyte membrane

[0185] The bonding strength between the electrode and the polymer electrolyte membrane of the membrane-electrode assemblies for fuel cells prepared in Examples 1-1 to 1-3 and Comparative Example 1 was evaluated as follows using a universal material testing machine (UTM_5966, Instron).

[0186] A specimen was prepared by cutting the electrode portion of a manufactured membrane-electrode assembly for a fuel cell to a width of 15 mm and a length of 30 mm, and the shape of the electrode detached upon impact when the specimen was stretched and fractured was analyzed using a program elongation rate of 500 mm / min.

[0187] The results are shown in Figures 4 and 5. Figure 4 is a photograph showing the results of evaluating the bonding strength between the electrode and the polymer electrolyte membrane of the membrane-electrode assembly for a fuel cell prepared in Examples 1-2, and Figure 5 is a photograph showing the results of evaluating the bonding strength between the electrode and the polymer electrolyte membrane of the membrane-electrode assembly for a fuel cell prepared in Comparative Example 1.

[0188] Referring to FIGS. 4 and 5, in the case of Example 1-2, in which a composition for forming an electrode is prepared including a plasticizer containing an aromatic carboxylate substituent and a membrane-electrode assembly is prepared including an electrode prepared using the same and a polymer electrolyte membrane containing a hydrocarbon ion conductor, it can be confirmed that the transfer process is easily performed due to the plasticizer even though a hydrocarbon ion conductor is included, and the electrode remains well bonded even after the polymer electrolyte membrane is broken following the bonding strength evaluation. However, in the case of Comparative Example 1, in which this is not the case, it can be confirmed that the electrode detaches after the polymer electrolyte membrane is broken and pulverized, which can be confirmed as the part marked in red in FIG. 5.

[0189]

[0190] 3. Evaluation of Performance and Durability of Membrane-Electrode Assembly

[0191] The membrane-electrode assemblies for fuel cells prepared in Examples 1-1 to 1-3 and Comparative Example 1 were evaluated for cell performance and chemical durability as follows.

[0192] Active area 25 cm 2The output performance of the membrane-electrode assembly manufactured was evaluated through IV measurements. 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 a temperature 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 0.6V, and a higher result value indicates superior output performance.

[0193] 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 for the fuel cell, 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.

[0194] Battery Performance Evaluation (A / cm) 2 )OCV Voltage Loss (%) Example 1-11.3519 Example 1-21.2813 Example 1-31.3317 Comparative Example 11.1820 (240 hours)

[0195] Referring to Table 1 above, it can be confirmed that the membrane-electrode assemblies of Examples 1-1 to 1-3, which include an electrode prepared using a composition for forming an electrode containing a plasticizer containing aromatic carboxylate substituents as in the hydrothermal evaluation or adhesion strength evaluation, and a polymer electrolyte membrane containing a hydrocarbon-based ion conductor, exhibit not only superior output characteristics but also superior durability compared to Comparative Example 1, which does not. This indicates that the introduction of a plasticizer containing aromatic carboxylate substituents promotes a larger amount of ion conductors within the electrode and the amorphous phase of the ion conductors at the interface between the electrode and the polymer electrolyte membrane, thereby improving ion conductivity through increased flexibility, while also being effective in improving adhesion between materials and maintaining thermal stability.

[0196]

[0197] (Electrolytic cell)

[0198] 1. Evaluation of Performance and Durability of Membrane-Electrode Assembly

[0199] The membrane-electrode assemblies for water electrolysis cells prepared in Examples 2-1 to 2-2 and Comparative Example 2 were evaluated for cell performance and chemical durability as follows.

[0200] The membrane-electrode assembly for the water electrolysis cell prepared in Examples 2-1 to 2-2 and Comparative Example 2 was applied inside a unit cell designed and fabricated for the water electrolysis cell, and a protocol was applied to measure voltage and resistance at specific currents from 1 mA to 20 A under conditions of cell temperature 80°C, water temperature 80°C, and flow rate 5 ml / min. The current density was measured at a voltage of 1.8 V, and the higher the result value, the better the output performance.

[0201] Chemical durability was evaluated after the initial performance evaluation of the above membrane-electrode assembly at a cell temperature of 80°C and a current density of 1 A / cm². 2The voltage growth rate was measured after driving a constant current for 500 hours. The voltage growth rate was measured using a BioLogic instrument, calculated according to Equation 1 below, and the results are shown in Table 3 below.

[0202] [Equation 1]

[0203] Voltage Increase Rate (%) = (Voltage after driving - Initial voltage) / (Initial voltage) × 100

[0204] Battery Performance Evaluation (A / cm) 2 Voltage Increase Rate (%) Example 2-1 1.978.3 Example 2-2 2.019.1 Comparative Example 2 1.7516.2

[0205] Referring to Table 2 above, the membrane-electrode assemblies of Examples 2-1 and 2-2 exhibited improved performance and chemical durability compared to the membrane-electrode assembly of Comparative Example 2. This confirms that Examples 2-1 and 2-2, which include oxygen-generating electrodes and hydrogen-generating electrodes manufactured using an electrode-forming composition containing a plasticizer comprising aromatic carboxylate substituents, exhibit superior output and durability compared to Comparative Example 2, which does not. This indicates that the introduction of a plasticizer containing aromatic carboxylate substituents is effective not only in fuel cell operating environments but also in the underwater environment of water electrolysis cells, and is effective not only in the case of Example 2-2, where the ion conductors of the electrode and the polymer electrolyte membrane are identical, but also in the case of Example 2-2, where the ion conductors of the electrode and the polymer electrolyte membrane are different. Although preferred embodiments have been described in detail above, the scope of 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 rights.

[0206] [Explanation of the symbol]

[0207] 10: First electrode

[0208] 20: Second electrode

[0209] 30: Polymer electrolyte membrane

[0210] 100: Membrane-electrode assembly

Claims

1. A first catalyst; a first ion conductor; and a plasticizer comprising an aromatic carboxylate substituent; comprising, Composition for forming electrodes.

2. In Paragraph 1, The above aromatic carboxylate substituent comprises a dibenzoate group, Composition for forming electrodes.

3. In Paragraph 1, The plasticizer comprising the above aromatic carboxylate substituent comprises a compound represented by the following chemical formula 1, Electrode forming composition: [Chemical Formula 1] In the above chemical formula 1, X comprises a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted arylene group, or an ether group represented by the chemical formula 2 below. [Chemical Formula 2] In the above chemical formula 2, Z1 and Z2 are each independently a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group, and n is an integer from 1 to 4.

4. In Paragraph 3, In the above chemical formula 1, X is an unsubstituted alkylene group, Composition for forming electrodes.

5. In Paragraph 3, In the above chemical formula 1, X comprises an ether group represented by chemical formula 2, and in the above chemical formula 2, Z1 and Z2 are each independently unsubstituted alkylene groups, and n=1, Composition for forming electrodes.

6. In Paragraph 1, The plasticizer comprising the above aromatic carboxylate substituent comprises dipropylene glycol dibenzoate (DPGDB), diethylene glycol dibenzoate (DEGDB), 1,3-propanediyl dibenzoate, 1,4-butanediyl dibenzoate, 1,5-pentanediyl dibenzoate, 1,6-hexanediyl dibenzoate, or a combination thereof. Composition for forming electrodes.

7. In Paragraph 1, The plasticizer comprising the above aromatic carboxylate substituent is included in an amount of 0.1% to 20% by weight based on 100% by weight of the electrode-forming composition, Composition for forming electrodes.

8. In Paragraph 1, The first catalyst above comprises a precious metal or a precious metal oxide, Composition for forming electrodes.

9. In Paragraph 1, The first ion conductor comprises a fluorine-based ion conductor, a hydrocarbon-based ion conductor, or a combination thereof. Composition for forming electrodes.

10. A first catalyst; a first ion conductor; and a plasticizer comprising an aromatic carboxylate substituent; comprising, electrode.

11. In Paragraph 10, The content of a plasticizer containing aromatic carboxylate substituents in the electrode is 10 weight% or less with respect to 100 weight% of the electrode, electrode.

12. The first electrode where the oxidation reaction takes place, A second electrode where a reduction reaction takes place, and It includes a polymer electrolyte membrane located between the first electrode and the second electrode, and The first electrode, the second electrode, or both are electrodes according to claim 10, Membrane-electrode assembly.

13. In Paragraph 12, The first electrode, the second electrode, or both include a first ion conductor, and The above polymer electrolyte membrane includes a second ion conductor, and The first ion conductor and the second ion conductor both include fluorine-based ion conductors, or At least one of the first ion conductor and the second ion conductor comprises a hydrocarbon-based ion conductor. Membrane-electrode assembly.

14. A step of preparing an electrode-forming composition according to any one of claims 1 to 9; A step of manufacturing an electrode using the above electrode-forming composition; and The method comprises the step of manufacturing a membrane-electrode assembly using the above electrode; and The electrode manufactured above is a first electrode where an oxidation reaction occurs, a second electrode where a reduction reaction occurs, or an electrode for both. Method for manufacturing a membrane-electrode assembly.

15. In Paragraph 14, The step of manufacturing the above electrode is, The above electrode-forming composition is prepared by applying it to a release film and drying it, or The above electrode-forming composition is prepared by applying it to a polymer electrolyte membrane and then drying it. Method for manufacturing a membrane-electrode assembly.

16. In Paragraph 15, In the step of manufacturing the above electrode The above drying is performed at a temperature of 25℃ to 90℃ for 8 hours or more, Method for manufacturing a membrane-electrode assembly.

17. In Paragraph 14, The step of manufacturing a membrane-electrode assembly using the above electrode is, The above electrode is manufactured by transferring it to at least one surface of a polymer electrolyte membrane by applying heat and pressure, or The method of manufacturing by forming an electrode on a polymer electrolyte membrane on a surface other than the one where the electrode prepared using the electrode-forming composition is not located. Method for manufacturing a membrane-electrode assembly.

18. In Paragraph 17, The step of manufacturing a membrane-electrode assembly including the above electrode When the above electrode is manufactured by transferring it to at least one surface of a polymer electrolyte membrane by applying heat and pressure, The above heat is performed at a temperature of 80℃ to 200℃, and The above pressure is 5 kgf / cm² 2 Up to 200 kgf / cm² 2 Performed under the pressure of, Method for manufacturing a membrane-electrode assembly.

19. An electrochemical cell comprising a membrane-electrode assembly according to paragraph 12.

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