Polymer electrolyte membrane, method for manufacturing same, membrane-electrode assembly comprising same, water electrolysis cell, and fuel cell

Abstract

The present invention relates to a polymer electrolyte membrane, a method for manufacturing same, a membrane-electrode assembly comprising same, a water electrolysis cell, and a fuel cell. The polymer electrolyte membrane comprises: an ion conductor including a substituent selected from a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose. The polymer electrolyte membrane exhibits excellent mechanical properties, ease of impregnation with the ion conductor, thermal stability, moldability, biodegradability, gas permeability, and the like.

Description

Polymer electrolyte membrane, method for manufacturing the same, membrane-electrode assembly including the same, water electrolysis cell, and fuel cell

[0001] The invention relates to a polymer electrolyte membrane, a method for manufacturing the same, a membrane-electrode assembly including the same, a water electrolysis cell, and a fuel cell.

[0002]

[0003] Recent energy demands and environmental conditions require sustainable supply, eco-friendliness, and high efficiency, and among these, hydrogen is attracting attention as a raw material for renewable energy.

[0004] In a system of a Polymer Electrolyte Membrane Water Electrolysis Cell (PEMWE), the Membrane Electrode Assembly (MEA) that actually generates hydrogen has a structure in which an oxygen evolution electrode, where the oxygen evolution reaction takes place, and a hydrogen evolution electrode, where the hydrogen evolution reaction takes place, are positioned with respect to a polymer electrolyte membrane containing a hydrogen ion-conducting polymer.

[0005] Meanwhile, polymer electrolyte fuel cells (PEMFCs) are known to be the most promising for transportation systems as well as small-scale stationary power generation equipment, as they operate at low temperatures compared to other fuel cells and enable miniaturization due to their high power density.

[0006] Conventionally, polymer electrolyte membranes for water electrolysis or fuel cells have used a porous support made of polytetrafluoroethylene (PTFE), and an ion conductor has been impregnated into the porous support to be used as a polymer electrolyte membrane.

[0007] However, porous supports made of polytetrafluoroethylene (PTFE) have internal pores that are too small, resulting in very high internal pressure and making it difficult to impregnate with ion conductors; furthermore, unfilled pores fail to form ion transport channels and thus act as resistance to the polymer electrolyte membrane.

[0008] On the other hand, when using a PEEK support, high UV sensitivity and high polymer degradation at high temperatures make handling and membrane formation difficult during manufacturing. Additionally, when applying hydrocarbon-based ion conductors, there is a problem of interfacial resistance occurring between the fluorine-based PTFE support and the ion conductor.

[0009]

[0010] One embodiment provides a polymer electrolyte membrane having advantages in thermal stability, moldability, biodegradability, gas permeability, etc., in addition to excellent mechanical properties and ease of impregnating with an ion conductor.

[0011]

[0012] One embodiment provides a polymer electrolyte membrane comprising: an ion conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose.

[0013]

[0014] The polymer electrolyte membrane of one embodiment has advantages in thermal stability, moldability, biodegradability, gas permeability, etc., in addition to excellent mechanical properties and ease of impregnating with ion conductors.

[0015] Accordingly, a water electrolysis cell or fuel cell manufactured by assembling a polymer electrolyte membrane of one embodiment as a membrane-electrode assembly may have excellent mechanical properties, electrochemical properties, thermal stability, moldability, etc.

[0016]

[0017] FIGS. 1 to 4 illustrate the form of a polymer electrolyte membrane according to one embodiment.

[0018] Figure 5 shows the performance evaluation results of the membrane-electrode assembly according to Evaluation Example 2.

[0019]

[0020] 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 implemented in various different structures and is not limited to the embodiments described herein.

[0021] In this specification, "combination thereof" means a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, a reaction product, etc.

[0022] 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.

[0023] In this specification, terms are used solely for the purpose of distinguishing one component from another. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0024]

[0025] polymer electrolyte membrane

[0026] One embodiment provides a polymer electrolyte membrane comprising: an ion conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose.

[0027]

[0028] The aforementioned nanocellulose is a natural polymer material abundant in nature that possesses high mechanical strength and elastic modulus, and exhibits low water content and water swelling while being hydrophilic, making it a material capable of replacing polytetrafluoroethylene (PTFE). Furthermore, nanocellulose forms nano-sized chain bundles, exhibiting excellent thermal stability, moldability, and biodegradability, and possesses superior gas permeability due to its high specific surface area.

[0029] The above ion conductor comprises a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof, wherein the sulfonic acid group has the effect of exchanging cations by forming a hydrogen ion transfer channel, and the ammonium group has the effect of exchanging anions by forming a hydroxyl ion transfer channel.

[0030] A polymer electrolyte membrane of one embodiment comprising an ion conductor defined as above and nanocellulose has advantages in thermal stability, moldability, biodegradability, gas permeability, etc., in addition to excellent mechanical properties and ease of impregnating the ion conductor.

[0031] Accordingly, a water electrolysis cell or fuel cell manufactured by assembling a polymer electrolyte membrane of one embodiment as a membrane-electrode assembly may have excellent mechanical properties, electrochemical properties, thermal stability, moldability, etc.

[0032]

[0033] A polymer electrolyte membrane of one embodiment is described in detail below.

[0034]

[0035] ion conductor

[0036] The above ion conductor comprises a substituent that is a sulfonic acid group, an ammonium group, or a combination thereof.

[0037] For example, the above ion conductor is a compound containing a sulfonic acid group, such as perfluorosulfonic acid (PFSA), polyphenylene oxide, polyphenylene, polyfluorene, poly(aryl piperidinium), polynorbornene, polystyrene (PS), polybenzimidazole (PBI), polyphenylene sulfide, polysulfone (PSU), polyaryletherketone, polyethylene, poly(ethylene tetrafluoroethylene), polyphenylene ether, polypyrrole, polythiophene, polycarbazole, polyaniline, polyindole, and polypyrrole. It may be a polyionic liquid, or a combination thereof.

[0038] The above perfluorosulfonic acid can be represented by the following chemical formula 1:

[0039] [Chemical Formula 1] C n F (2n+1) SO3H

[0040] In the above chemical formula 1, n can be an integer from 5 to 100.

[0041] The above perfluorosulfonic acid may have an equivalent weight of 720 to 1200 g / equivalent as measured by the acid-base substitution method.

[0042]

[0043] nanocellulose

[0044] As for the nanocellulose, the cellulose nanofibrils (NF) and the cellulose nanocrystals (NC) may be used in combination, or each may be used individually.

[0045] When using a mixture, the weight ratio of the cellulose nanofibrils (NF) and the cellulose nanocrystals (NC) can be mixed in a ratio of 1:99 to 99:1.

[0046] The above cellulose nanocrystals, the above cellulose nanofibrils, or a combination thereof can aggregate to form the above cellulose nanofibers.

[0047] The polymer electrolyte membrane formed with the above-mentioned cellulose nanofibers can exhibit thermal stability, moldability, high strength, and a low thermal expansion rate, and as the content of the above-mentioned cellulose nanofibers increases, the flexibility and toughness of the polymer electrolyte membrane can be improved.

[0048] Their zeta potential values ​​can be +10 to -80 Mv.

[0049]

[0050] The cellulose nanocrystals may have a diameter of 2 to 70 nm and a length of 40 to 250 nm; and the cellulose nanofibrils may have a diameter of 3 to 300 nm and a length of 500 nm to 20 μm.

[0051] The above cellulose nanocrystals are composed solely of the crystalline form of cellulose, and when forming a polymer electrolyte membrane, they have high planar strength and can improve water swelling stability.

[0052] The above cellulose nanofibrils include both crystalline and amorphous forms of cellulose and have a fiber-like structure, which can improve the elastic modulus in the planar and thickness directions when forming a polymer electrolyte membrane.

[0053]

[0054] The cellulose nanofibrils and the cellulose nanocrystals may each be independently modified with substituents that are acetyl, succinyl, carbonyl, methyl, hydroxyethyl, carboxymethyl, sulfate, acyl, silyl, or a combination thereof.

[0055] In the case of hydrophilic substituents such as hydroxyethyl, sulfate, or carbonyl among the above, water dispersibility and compatibility with polar polymers can be improved, and physical properties such as mechanical strength can be improved by facilitating hydrogen bonding or electrostatic interactions with other hydrophilic molecules or polymers.

[0056] Meanwhile, hydrophobic substituents such as methyl, acetyl, or acyl groups can improve compatibility with non-polar or hydrophobic polymers such as PTFE and improve thermal stability at high temperatures.

[0057] Methods for modifying the above-mentioned substituents include chemical modification, physical modification, and polymer substitution. The chemical modification method may include esterification, oxidation, and silane coupling; the physical modification method may include plasma treatment and UV / Ozone treatment; and the polymer substitution method may include grafting-from, grafting-to, and grafting-through.

[0058]

[0059] Weight ratio of ion conductor and nanocellulose

[0060] The weight ratio of the ion conductor and the nanocellulose may be 100:0.1 to 100:30.

[0061] Within the above range, the strength and flexibility of cellulose can be secured, and the ionic conductivity of the polymer electrolyte membrane can be maintained.

[0062]

[0063] Structure of polymer electrolyte membranes

[0064] The above polymer electrolyte membrane may have a structure of a single membrane or a reinforced membrane.

[0065] FIGS. 1 to 4 illustrate the structure of a polymer electrolyte membrane according to one embodiment, and will be explained below with reference to FIGS. 1 to 4.

[0066]

[0067] The above single membrane may be composed of the ion conductor and the cellulose, as shown in FIG. 1.

[0068]

[0069] The above reinforcing membrane may be any one of three structures.

[0070] For example, it may include a support; and a first membrane located on one or both sides of the support and composed of the ion conductor and the cellulose. This can be described as the structure of FIG. 2.

[0071] For example, it may include a support; a first membrane located on one or both sides of the support and composed of the ion conductor and the cellulose; and a second membrane located on the first membrane and composed of the ion conductor. This can be described as the structure of FIG. 3.

[0072] For example, it may include a first membrane composed of the ion conductor and the cellulose; and a second membrane located on one or both sides of the first membrane and composed of the ion conductor. This can be described as the structure of FIG. 4.

[0073] The support commonly mentioned in the above examples may include expanded-polytetrafluoroethylene (e-PTFE).

[0074]

[0075] Compared to the case of the above single-film structure, it may have higher mechanical properties than the above reinforced film structure, but is not limited thereto.

[0076]

[0077] Method for manufacturing a polymer electrolyte membrane

[0078] The polymer electrolyte membrane of the above-described embodiment can be manufactured as a single membrane or a reinforced membrane structure.

[0079]

[0080] One embodiment provides a method for manufacturing a polymer electrolyte membrane, comprising the steps of: preparing a first composition comprising an ion conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; and coating the first composition onto a release film.

[0081] Finally, the step of removing the release film may be further included.

[0082] Through this, a single membrane composed of the above-mentioned ion conductor and the above-mentioned cellulose can be obtained.

[0083]

[0084] One embodiment provides a method for manufacturing a polymer electrolyte membrane, comprising the steps of: preparing a first composition comprising an ion conductor having a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; coating the first composition onto a release film to form a first membrane; and laminating a support onto the first membrane to form a first membrane and a support on the first membrane.

[0085] The method may further include the step of laminating a support onto the first film and then coating the first composition onto the support.

[0086] Through this, a reinforcing film can be obtained, comprising a support; and a first film located on one or both sides of the support and composed of the ion conductor and the cellulose.

[0087]

[0088] One embodiment provides a method for manufacturing a polymer electrolyte membrane, comprising the steps of: preparing a second composition comprising a sulfonic acid group, an ammonium group, or a combination thereof, and nanocellulose; forming a first film by coating the second composition on one or both sides of a support; preparing a third composition comprising a sulfonic acid group, an ammonium group, or a combination thereof, and a substituent thereof; forming a second film by coating the third composition on a release film; and laminating the support having the first film formed thereon onto the second film.

[0089] The method may further include the step of laminating a support having the first film formed thereon onto the second film, and then coating the third composition onto the support or the first film.

[0090] Through this, a reinforced membrane can be obtained comprising: a support; a first membrane located on one or both sides of the support and composed of the ion conductor and the cellulose; and a second membrane located on the first membrane and composed of the ion conductor.

[0091]

[0092] One embodiment provides a method for manufacturing a polymer electrolyte membrane, comprising the steps of: preparing a third composition comprising an ion conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; forming a second membrane by coating the third composition on a release film; preparing a second composition comprising an ion conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; and forming a first membrane by coating the second composition on the second membrane.

[0093] The method may further include the step of forming a first film by coating the second composition on the second film, and then coating the third composition on the first film.

[0094] Finally, the step of removing the release film may be further included.

[0095] Through this, a reinforced membrane can be obtained comprising: a first membrane composed of the ion conductor and the cellulose; and a second membrane located on one or both sides of the first membrane and composed of the ion conductor.

[0096]

[0097] The above release film is not particularly limited as long as it is a film having release properties, but may include polyethylene terephthalate (PET), polyimide (PI), fluorinated ethylene propylene (FEP), or a combination thereof.

[0098]

[0099] In the first to third compositions above, the solvent may each independently be a water-soluble solvent, an organic solvent, an ionic solvent, or a combination thereof.

[0100] The above-mentioned water-soluble solvent includes water or a pH-adjusted aqueous solution, and the pH adjustment can be performed using reagents such as hydrochloric acid or sodium hydroxide.

[0101] The above organic solvents use polar and non-polar solvents, and the polar solvents include alcohols such as ethanol, methanol, and IPA, and the non-polar solvents may include solvents such as toluene, hexane, and chloroform.

[0102] The above ionic solvent may include 1-butyl-3-methylimidazolium chloride, etc.

[0103] In addition, it may include solvents such as green solvent, biocompatible solvent, DES (Deep eutectic solvent), etc.

[0104]

[0105] The weight of nanocellulose in the first composition or the second composition may be 1 to 50 parts by weight per 100 parts by weight of solvent.

[0106] The weight of the ion conductor in the third composition may be 1 to 50 parts by weight per 100 parts by weight of the solvent.

[0107] The weight of nanocellulose in the first composition or the second composition may be 0.1 to 30 parts by weight, 5 to 20 parts by weight, or 5 to 10 parts by weight based on 100 parts by weight of the ion conductor.

[0108]

[0109] High-pressure dispersion, ultrasonic dispersion, homogenizer, stirring, etc., may be used as dispersion methods for preparing the first to third compositions above.

[0110] The content of the ion conductor in the first dispersion or the third dispersion may be 0.1 to 30 parts by weight, or 0.1 to 5 parts by weight, based on 100 parts by weight of solvent.

[0111] The application method of the first composition above may use hand spray, electrospinning, slot-die coating, comma coating, spin-coating, direct casting method, dip coating, or a combination thereof.

[0112] The method of applying the second composition above may use hand spray, electrospinning, or a combination thereof.

[0113] The application method of the third composition above may use slot-die coating, comma coating, spin-coating, direct casting method, dip coating, or a combination thereof.

[0114]

[0115] After coating the above first to third compositions, drying and heat treatment can be performed.

[0116] The drying temperature may be 60 to 250 ℃, and the heat treatment temperature may be 150 to 450 ℃.

[0117]

[0118] Membrane-electrode assembly, water electrolysis cell, and fuel cell

[0119] One embodiment provides a membrane-electrode assembly for a water electrolysis cell comprising: a hydrogen generating electrode; an oxygen generating electrode; and a polymer electrolyte membrane according to the above-described embodiment located between the hydrogen generating electrode and the hydrogen generating electrode.

[0120] One embodiment provides a water electrolysis cell comprising a membrane-electrode assembly for the water electrolysis cell.

[0121]

[0122] One embodiment provides a membrane-electrode assembly for a fuel cell comprising: an anode electrode; a cathode electrode; and a polymer electrolyte membrane of the above-described embodiment located between the anode electrode and the cathode electrode.

[0123] One embodiment provides a fuel cell comprising a membrane-electrode assembly for the fuel cell.

[0124]

[0125] A water electrolysis cell or fuel cell manufactured by assembling the polymer electrolyte membrane according to the above-described embodiment as a membrane-electrode assembly may have excellent mechanical properties, electrochemical characteristics, thermal stability, moldability, etc.

[0126]

[0127] The above membrane-electrode assembly for a water electrolysis cell and the water electrolysis cell including the same are described below.

[0128] The catalyst layer included in the oxygen generation electrode comprises a catalyst for an oxygen generation reaction and an ion conductor, and the catalyst for the oxygen generation reaction comprises active particles comprising a precious metal oxide.

[0129] The above precious metal oxide is not limited in type as long as it can be applied as a catalyst for the oxygen evolution reaction of a water electrolysis cell.

[0130] For example, the above precious metal oxide is IrO x (The above x is an integer from 1 to 3), RuO x (The above x is an integer from 1 to 3), IrMO x (M comprises Ru, Pt, Sn, Se, Sb, Ta, Te, Nb, W, Zn, Au or a combination thereof, and x is an integer from 1 to 3), or may comprise a combination thereof.

[0131] The above catalyst for the oxygen generation reaction may use only the active particle alone, or may further include a carrier that supports the active particle.

[0132] The above-mentioned carrier is not limited in type as long as it can be applied to a catalyst for the oxygen generation reaction of a water electrolysis cell.

[0133] For example, the carrier may be a metal oxide, and the carrier may be titanium dioxide (TiO2).

[0134] The above ion conductor is included to improve the adhesion of the catalyst layer and to transport hydrogen ions.

[0135] The ion conductor included in the oxygen generating electrode and the ion conductor included in the reinforced polymer electrolyte membrane for the water electrolysis cell may be the same.

[0136] The above hydrogen generation electrode may include a catalyst for a hydrogen generation reaction. The above catalyst for a hydrogen generation reaction may include active particles and a support material that supports the active particles.

[0137] The above active particles may include precious metals.

[0138] For example, 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 carrier may be a carbon-based carrier.

[0142] 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.

[0143] The oxygen generation electrode and the hydrogen generation electrode may each include only a catalyst layer comprising a catalyst for an oxygen generation reaction and a catalyst for a hydrogen generation reaction, respectively, but may also include an electrode substrate together with the catalyst layer.

[0144] At this time, the electrode substrate can perform the role of supporting the electrode while diffusing fuel and oxidant into the catalyst layer.

[0145] The above electrode substrate may be any known electrode substrate without specific limitations, but specifically, carbon paper, carbon cloth, carbon felt, or metal cloth that can be used as a conductive substrate (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).

[0146] The above electrode substrate may be treated with a fluorine-based resin for water repellency, in which case the reduction in reactant diffusion efficiency caused by water generated after operating the water electrolysis cell can be prevented.

[0147] As the above fluorine-based resin, polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxyvinyl ether, fluorinated ethylene propylene, polychlorotrifluoroethylene, or copolymers thereof may be used.

[0148]

[0149] A water electrolysis cell according to one embodiment may include the membrane-electrode assembly.

[0150] Since the above-mentioned water electrolysis cell is identical to the known one except for including the above-mentioned membrane-electrode assembly, a detailed description is omitted.

[0151]

[0152] The above-described membrane-electrode assembly for a fuel cell and the fuel cell including the same are described below.

[0153] A membrane-electrode assembly according to one embodiment is a membrane-electrode assembly comprising the polymer electrolyte membrane, wherein the anode electrode and a cathode electrode are positioned opposite each other, and the polymer electrolyte membrane is positioned between the anode electrode and the cathode electrode.

[0154] The above anode and cathode electrodes include an electrode substrate and a catalyst layer formed on the surface of the electrode substrate, and may further include a microporous layer containing conductive fine particles such as carbon powder or carbon black between the electrode substrate and the catalyst layer to facilitate material diffusion from the electrode substrate.

[0155] The catalyst layers of the anode and cathode electrodes described above contain a catalyst. Any catalyst that participates in the reaction of the cell and is typically usable as a catalyst for a fuel cell may be used. Preferably, a platinum-based metal may be used.

[0156] The above platinum-based metal may include one selected from the group consisting of platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), platinum-M alloys, non-platinum alloys, and combinations thereof, and more preferably, a combination of two or more metals selected from the group of platinum-based catalyst metals may be used, but is not limited thereto, and any platinum-based catalyst metal available in the field of the present technology may be used without limitation.

[0157] The above M may correspond to one or more selected from the group consisting of palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), gallium (Ga), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), zinc (Zn), tin (Sn), molybdenum (Mo), tungsten (W), lanthanum (La), and rhodium (Rh). Specifically, the platinum alloy mentioned above may be used alone or in a mixture of two or more selected from the group consisting of 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, and combinations thereof.

[0158] In addition, the above-mentioned non-platinum alloy may be used alone or in a mixture of two or more selected from the group consisting of Ir-Fe, Ir-Ru, Ir-Os, Co-Fe, Co-Ru, Co-Os, Rh-Fe, Rh-Ru, Rh-Os, Ir-Ru-Fe, Ir-Ru-Os, Rh-Ru-Fe, Rh-Ru-Os, and combinations thereof.

[0159] The above catalyst may be used as the catalyst itself (black) or supported on a carrier.

[0160]

[0161] A fuel cell according to one embodiment may include the membrane-electrode assembly.

[0162] Since the above fuel cell is identical to the known one except for including the above membrane-electrode assembly, a detailed description is omitted.

[0163]

[0164] 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.

[0165]

[0166] (Composition)

[0167]

[0168] Preparation Example 1: PFSA+NC Composition

[0169] A first composition is prepared by mixing perfluorosulfonic acid (PFSA, EW 720 g / equivalent) : nanocellulose : water : N-Propyl Alcohol (NPA) in a weight ratio of 20 : 2 : 50 : 28.

[0170] The above nanocellulose is a powder-type cellulose nanocrystal, with a particle size of 1 to 50 μm, a crystal diameter of 2.3 to 4.5 nm, a length of 44 to 108 nm, and a crystallinity of 88%.

[0171]

[0172] Preparation Example 2: PFSA+NC Composition

[0173] A second composition was prepared by first dispersing a nanocellulose content of 10 wt% in water using a primary resonant acoustic mixer, adding 5 wt% of PFSA and 20 wt% of NPA per 100 wt% of nanocellulose and per 100 wt% of water, and then secondarily dispersing using a high-pressure disperser.

[0174]

[0175] Preparation Example 3: PFSA Composition

[0176] A third dispersion composition is prepared with a weight ratio of PFSA : water : NPA = 20 : 50 : 30, and a first coating is applied to a polyimide film fixed on a glass plate using a direct casting method.

[0177]

[0178] (Single-membrane PEM)

[0179]

[0180] Example 1: PFSA+NC single membrane

[0181] After fixing a polyimide film (PI Advanced Sodae Co., GF300) on a glass plate, the first composition was coated according to a direct casting method.

[0182] A polymer electrolyte membrane was prepared by drying in an oven in the order of 60 ℃, 80 ℃, 100 ℃, and 120 ℃, and then performing heat treatment for 5 to 10 minutes at a temperature within the range of 180 ℃ to 220 ℃.

[0183] Accordingly, the obtained polymer electrolyte membrane can be described as a PFSA+NC monolayer having the structure of Fig. 1.

[0184]

[0185] Comparative Example 1: PFSA single membrane

[0186] After fixing a polyimide film (PI Advanced Materials, GF300) on a glass plate, the third composition was coated according to a direct casting method.

[0187] A polymer electrolyte membrane was prepared by drying in an oven at 60℃, 80℃, 100℃, and 120℃ in sequence, followed by heat treatment at a temperature within the range of 200℃ to 220℃ for 5 to 10 minutes.

[0188]

[0189] (Reinforced PEM)

[0190]

[0191] Example 2-1 First film (PFSA+NC coating layer) / Support (e-PTFE) / First film (PFSA+NC coating layer) reinforced film

[0192] After fixing a polyimide film (PI Advanced Materials, GF300) on a glass plate, a first film was formed by coating using the first composition according to a direct casting method.

[0193] After placing an e-PTFE (expanded-polytetrafluoroethylene) support with a porosity of about 87% on the first film, the first composition was coated according to a direct casting method. Accordingly, a structure of the first film (PFSA+NC coating layer) / support (e-PTFE) / first film (PFSA+NC coating layer) was formed.

[0194] A polymer electrolyte membrane was prepared by drying in an oven in the order of 60 ℃, 80 ℃, 100 ℃, and 120 ℃, and then performing heat treatment for 5 to 10 minutes at a temperature within the range of 180 ℃ to 220 ℃.

[0195] Accordingly, the obtained polymer electrolyte membrane can be described as a first membrane (PFSA+NC coating layer) / support (e-PTFE) / first membrane (PFSA+NC coating layer) reinforced membrane having the structure of FIG. 2.

[0196]

[0197] Example 2-2: Second film (PESA coating layer) / First film (PFSA+NC coating layer) / Support (e-PTFE) / First film (PFSA+NC coating layer) / Second film (PESA coating layer) Reinforcement film

[0198] After spraying the second composition onto both sides of an e-PTFE (expanded-polytetrafluoroethylene) support using a spray, the mixture is dried in a 60°C oven for about 1 hour. Through this, a primary reinforcing film can be formed having a structure comprising a support; and a first film (PFSA+NC coating layer) located on both sides of the support and composed of an ion conductor and cellulose.

[0199] Independently, the third composition was coated onto a polyimide film fixed on a glass plate according to a direct casting method to form a second film (PESA coating layer) made of an ion conductor.

[0200] After placing the first reinforcing film on the second film, the third composition was coated according to the direct casting method. Accordingly, a structure of the second film (PESA coating layer) / first film (PFSA+NC coating layer) / support (e-PTFE) / first film (PFSA+NC coating layer) / second film (PESA coating layer) was formed.

[0201] A polymer electrolyte membrane was prepared by drying in an oven in the order of 60 ℃, 80 ℃, 100 ℃, and 120 ℃, and then performing heat treatment for 5 to 10 minutes at a temperature within the range of 180 ℃ to 220 ℃.

[0202] Accordingly, the obtained polymer electrolyte membrane can be described as a second membrane (PESA coating layer) / first membrane (PFSA+NC coating layer) / support (e-PTFE) / first membrane (PFSA+NC coating layer) / second membrane (PESA coating layer) reinforced membrane having the structure of FIG. 3.

[0203]

[0204] Example 2-3: Second film (PESA coating layer) / First film (PFSA+NC coating layer) / Second film (PESA coating layer) reinforced film

[0205] After applying the third composition as a first coating on a polyimide film fixed on a glass plate according to a direct casting method, the film was dried in a 60°C oven for 30 minutes to form a second film (PESA coating layer) made of an ion conductor.

[0206] After spray-coating the second composition onto the PESA coating layer, the mixture was dried in a 60°C oven for 10 minutes to form a first film (PFSA+NC coating layer) composed of an ion conductor and cellulose.

[0207] The third composition was coated onto the first film (PFSA+NC coating layer) using a direct casting method. Accordingly, a structure of second film (PESA coating layer) / first film (PFSA+NC coating layer) / second film (PESA coating layer) was formed.

[0208] A polymer electrolyte membrane was prepared by drying in an oven in the order of 60 ℃, 80 ℃, 100 ℃, and 120 ℃, and then performing heat treatment for 5 to 10 minutes at a temperature within the range of 180 ℃ to 220 ℃.

[0209] Accordingly, the obtained polymer electrolyte membrane can be described as a second membrane (PESA coating layer) / first membrane (PFSA+NC coating layer) / second membrane (PESA coating layer) reinforced membrane having the structure of Fig. 4.

[0210]

[0211] Comparative Example 2: First film (PFSA coating layer) / support (e-PTFE) / first film (PFSA coating layer) reinforced film

[0212] After fixing a polyimide film (PI Advanced Materials, GF300) on a glass plate, the third composition was coated according to a direct casting method.

[0213] After placing an e-PTFE support on the third composition, the third composition was coated according to a direct casting method. Accordingly, a first film (PFSA coating layer) / support (e-PTFE) / first film (PFSA coating layer) structure was formed.

[0214] A polymer electrolyte membrane was prepared by drying in an oven at 60℃, 80℃, 100℃, and 120℃ in sequence, followed by heat treatment at a temperature within the range of 200℃ to 220℃ for 5 to 10 minutes.

[0215]

[0216] Evaluation Example 1: PEM Evaluation

[0217] (1) Density

[0218] The density of the polymer electrolyte membranes prepared according to the above examples and comparative examples was evaluated as follows.

[0219] Density was measured using the density kit of the ML54T instrument from Mettler Toledo. The solution was distilled water, and the density was measured using the buoyancy of water.

[0220] The results are shown in Table 1 below.

[0221]

[0222] Density (g / cm³) 3 Example 11.90 Example 2-11.87 Example 2-21.94 Example 2-31.84 Comparative Example 11.93 Comparative Example 21.85

[0223] (2) Compressive Strength The compressive strength of the polymer electrolyte membranes prepared according to the above examples and comparative examples was measured as follows.

[0224] The above compressive strength was measured using an Instron 6800 series machine with a crosshead speed of 10 mm / min, equipped with a 1 kN load cell and a puncture fixtures accessory (MIL-STD-3010, Instron).

[0225] The results are shown in Table 2 below.

[0226]

[0227] Compressive Strength (N) Example 1 31.6 Example 2 145.4 Example 2 248.6 Example 2 335.4 Comparative Example 1 24.6 Comparative Example 2 35.4

[0228] (3) Wetting expansion rate and moisture absorption rate

[0229] The wetting expansion rate and water absorption rate of the polymer electrolyte membranes prepared according to the above examples and comparative examples were measured as follows.

[0230] After drying the above polymer electrolyte membrane in a vacuum oven at 80°C for 24 hours, the weight of the membrane (W dry ) and the length (L) in the plane direction (In-plane, IP) and thickness direction (Through-plane, TP) dry,IP, L dry,TP ) is measured. Afterwards, the membrane is immersed in ultrapure water at room temperature for 24 hours, then removed, the surface water is immediately removed, and the weight of the membrane (W) is immediately measured. wet ) and length (L) in the plane direction (IP) and thickness direction (TP) wet,IP, L wet, TP ) is measured. At 80°C, the swelling ratio and water uptake in the plane direction and thickness direction according to the above method are calculated using the following Equations 1 to 3, respectively. The results are shown in Table 11 below.

[0231] [Equation 1]

[0232] Wet expansion rate (%) in the face direction (IP) = (L wet,IP -L dry,IP ) / L dry,IP Х100

[0233] [Equation 2]

[0234] Wet expansion rate (%) in the thickness direction (TP) = (L wet,TP -L dry,TP ) / L dry,TP Х100

[0235] [Equation 3]

[0236] Water absorption rate (%) = (W wet -W dry ) / W dry Х100

[0237] Wet Expansion Rate (%) Water Absorption Rate (%) IPTP Example 1 4 2.5 0 3.4 0 48.32 Example 2-1 19.1 8 0.1 9 16.06 Example 2-2 24.5 5 1.1 4 25.40 Example 2-3 35.8 8 1.4 9 31.70 Comparative Example 1 5 3.7 8 12.6 5 29.78 Comparative Example 2 13.1 24.7 0 29.32

[0238] (4) Ionic conductivity

[0239] The planar hydrogen ion conductivity of the polymer electrolyte membranes prepared according to the above examples and comparative examples was measured as follows.

[0240] The above in-plane ion conductivity was calculated using Equation 4 below, based on membrane resistances measured at 20°C, 60°C, and 80°C temperatures and immersion in water using a 1225B Frequency Response Analyzer (Solartron). The effective membrane area was 1 cm². 2 It was.

[0241] [Equation 4]

[0242] Ionic Conductivity (S / cm) = Electrolyte Membrane Thickness (cm) / Resistance (ohm) X Effective Measurement Area (cm²) 2 )

[0243] The results are shown in Table 4 below.

[0244] 20 ℃ 50 ℃ 80 ℃ Example 10.21 00.357 0.495 Example 2-10.12 20.21 30.335 Example 2-20.13 50.247 0.351 Example 2-30.164 0.261 0.365 Comparative Example 10.249 0.44 50.605 Comparative Example 20.13 70.258 0.330

[0245] Evaluation Example 2: Water Electrolysis Cell Evaluation

[0246] The water electrolysis performance of the polymer electrolyte membranes prepared according to the above examples and comparative examples was evaluated as follows.

[0247] The catalyst mixture for fabricating the hydrogen electrode (HER) is prepared by mixing 50 wt% Pt / C catalyst with a polymer binder at a ratio of 1:1.2 and a solid content ratio of 5 wt%. The catalyst loading is 1.0 mg / cm². 2An active area of ​​4 cm² is formed on an electrode coating substrate film using a spray coating method. 2 A hydrogen electrode was fabricated.

[0248] The catalyst mixture for fabricating the oxygen electrode (OER) is IrO X The catalyst and polymer binder are mixed so that the ratio is 1:0.2 and the solid content ratio is 5 wt%. An active area of ​​4 cm² is applied using the same coating method as the hydrogen electrode above so that the catalyst loading is 0.5 mg / cm². 2 The oxygen electrode was fabricated.

[0249] The hydrogen electrode, each polymer electrolyte membrane prepared according to the above examples and comparative examples, and the oxygen electrode were stacked in that order and hot-pressed at 150°C for 5 minutes.

[0250] Using a multi-channel potentiometer (Bio-Logic, HCP-803 Potentiostat) and pump (KNF Neuberger, SIMDOS 02 FEM 1.02S), water is supplied at atmospheric pressure at 80°C and a rate of 5 mL / min with an active area of ​​9 cm² 2 The performance of the membrane-electrode assembly manufactured was evaluated.

[0251] The performance evaluation of the membrane-electrode assembly at this time is shown in Fig. 1.

[0252]

[0253] conclusion

[0254] When considering the above evaluation examples 1 and 2 together, the polymer electrolyte membrane according to one embodiment represented by the example has advantages in thermal stability, moldability, biodegradability, gas permeability, etc., in addition to excellent mechanical properties and ease of impregnating with ion conductors.

[0255] Accordingly, a water electrolysis cell manufactured by assembling the above polymer electrolyte membrane as a membrane-electrode assembly may have excellent mechanical properties, electrochemical characteristics, thermal stability, moldability, etc.

[0256] Although only water electrolysis cells were evaluated here, the results for fuel cells can be inferred in the same way.

Claims

1. An ionic conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and containing nanocellulose, Polymer electrolyte membrane.

2. In Paragraph 1, The above ionic conductor is perfluorosulfonic acid (PFSA), polyphenylene oxide, polyphenylene, polyfluorene, poly(aryl piperidinium), polynorbornene, polystyrene (PS), polybenzimidazole (PBI), polyphenylene sulfide, polysulfone (PSU), polyaryletherketone, polyethylene, poly(ethylene tetrafluoroethylene), polyphenylene ether, polypyrrole, polythiophene, polycarbazole, polyaniline, polyindole, polypyrrole, and polyionic liquid. liquid), or a combination thereof, Polymer electrolyte membrane.

3. In Paragraph 2, The above perfluorosulfonic acid is represented by the following chemical formula 1, Polymer electrolyte membrane: [Chemical Formula 1] C n F (2n+1) SO3H In the above chemical formula 1, n is an integer from 5 to 100.

4. In Paragraph 3, The above perfluorosulfonic acid has an equivalent weight of 720 to 1200 g / equivalent as measured by the acid-base substitution method, Polymer electrolyte membrane.

5. In Paragraph 1, The above nanocellulose comprises cellulose nanofibrils (nanofibrils, NF), cellulose nanocrystals (nanocrystals, NC), or a combination thereof. Polymer electrolyte membrane.

6. In Paragraph 5, The above cellulose nanocrystals have a diameter of 2 to 70 nm and a length of 40 to 250 nm; The above cellulose nanofibrils have a diameter of 3 to 300 nm and a length of 500 nm to 20 μm, Polymer electrolyte membrane.

7. In Paragraph 1, The weight ratio of the ion conductor and the nanocellulose is 100:0.1 to 100:30, Polymer electrolyte membrane.

8. In Paragraph 1, The above polymer electrolyte membrane is a single membrane or a reinforced membrane, Polymer electrolyte membrane.

9. In Paragraph 8, The above single membrane is It is composed of the above-mentioned ion conductor and the above-mentioned cellulose; The above reinforcing film is A support; and a first membrane located on one or both sides of the support and composed of the ion conductor and the cellulose, or A support; a first membrane located on one or both sides of the support and composed of the ion conductor and the cellulose; and a second membrane located on the first membrane and composed of the ion conductor, or comprising A first membrane comprising the ion conductor and the cellulose; and a second membrane located on one or both sides of the first membrane and comprising the ion conductor. Polymer electrolyte membrane.

10. A step of preparing a first composition comprising an ionic conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; and A step comprising coating the above-mentioned first composition onto a release film, Method for manufacturing a polymer electrolyte membrane.

11. A step of preparing a first composition comprising an ionic conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; A step of forming a first film by coating the above-mentioned first composition onto a release film; and A step comprising laminating a support onto the first film, Method for manufacturing a polymer electrolyte membrane.

12. In Paragraph 11, After laminating a support on the first film, A further comprising the step of coating the first composition on the support, Method for manufacturing a polymer electrolyte membrane.

13. A step of preparing a second composition comprising an ionic conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; A step of forming a first film by coating the second composition on one or both sides of a support; A step of preparing a third composition comprising an ionic conductor having a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; A step of forming a second film by coating the third composition on a release film; and A step comprising laminating a support having the first film formed thereon onto the second film. Method for manufacturing a polymer electrolyte membrane.

14. In Paragraph 13, After stacking the support having the first film formed thereon on the second film, A method further comprising the step of coating the third composition on the support or the first film. Method for manufacturing a polymer electrolyte membrane.

15. A step of preparing a third composition comprising an ionic conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; A step of forming a second film by coating the third composition onto a release film; A step of preparing a second composition comprising an ionic conductor comprising a substituent which is a sulfonic acid group, an ammonium group, or a combination thereof; and nanocellulose; A method comprising the step of forming a first film by coating the second composition onto the second film. Method for manufacturing a polymer electrolyte membrane.

16. In Paragraph 15, After forming a first film by coating the second composition onto the second film, A method further comprising the step of coating the third composition on the first film. Method for manufacturing a polymer electrolyte membrane.

17. Hydrogen generating electrode; Oxygen generating electrode; and A polymer electrolyte membrane according to claim 1, positioned between the hydrogen generation electrode and the hydrogen generation electrode. Membrane-electrode assembly for water electrolysis cell.

18. A water electrolysis cell comprising a membrane-electrode assembly for a water electrolysis cell according to paragraph 17.

19. Anode electrode; cathode electrode; and A polymer electrolyte membrane according to claim 1, positioned between the anode electrode and the cathode electrode. Membrane-electrode assembly for fuel cell.

20. A fuel cell comprising a membrane-electrode assembly for a fuel cell according to paragraph 19.

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