WO2018048134A1 - Membrane-electrode interface adhesion layer for fuel cell, and membrane-electrode assembly and fuel cell using same - Google Patents

Abstract

The invention of the present application relates to: a membrane-electrode interface adhesion layer for a fuel cell; a membrane-electrode assembly (MEA)using same; and a fuel cell using same, wherein the membrane-electrode interface adhesion layer is for overcoming the problem of interfacial separation during operation of fuel cells due to insufficient compatibility between a hydrocarbon-based electrolyte membrane and a catalyst layer including a fluoride-based ionomer, and exhibits improved adhesion strength through a composition gradient of a hydrocarbon-based electrolyte polymer and a nafion polymer.

Description

Membrane-electrode interface adhesive layer for fuel cell, membrane-electrode assembly and fuel cell using same

The present invention is a fuel cell comprising a mixture of a hydrocarbon-based polymer and a fluorine-based polymer for overcoming the problem that the interface detaches during operation of the fuel cell due to lack of compatibility between the hydrocarbon-based polymer electrolyte membrane and the catalyst layer containing the fluorine ionomer. A membrane-electrode interface adhesive layer, comprising a composition gradient of a hydrocarbon-based polymer and a fluorine-based polymer in a thickness direction, and a membrane-electrode interface adhesive layer for a fuel cell, and a membrane-electrode assembly using the same ) And fuel cells.

This application claims priority based on Korean Patent Application No. 10-2016-0117196, filed on September 12, 2016, and all the contents disclosed in the specification and drawings of the application are incorporated in this application.

Recent depletion of fossil fuels, increased demand for pollution and electrical energy require the development of alternative energy sources. Therefore, many researchers are trying to invent new systems that can produce electrical energy. Among them, proton exchange membrane fuel cells (PEMFCs) using polymer electrolytes can convert chemical energy directly into electrical energy and emit non-toxic substances such as water, thereby providing alternative energy for automobiles and portable appliances. It is attracting considerable attention as a system. An important factor in the PEMFC is a polymer electrolyte membrane (PEM) that determines the performance and durability of the PEMFC and separates both electrodes. M). Therefore, high proton conductivity, strong mechanical properties, stable dimensions in water and low cost are essential for the selection of the polymer electrolyte membrane.

Representative Nafion among perfluorosulfonated PEMs is a commercialized material for proton exchange membrane fuel cells with high proton conductivity, good mechanical properties and excellent dimensional stability. However, Nafion has the disadvantage of high unit cost and limited use at high temperatures.

In order to solve this problem, many researchers are developing hydrocarbon membranes cheaper than Nafion, and the representative one of them is sulfonated poly (arylene ether sulfone) copolymer (SPAES). And hydrocarbon-based copolymers containing such aromatic structures have been widely studied in the past because of their thermal stability due to the aromatic structure, excellent mechanical strength and elongation, and low gas cross-mixing ability between the anode and the cathode. to be.

However, when the ion-conductive hydrocarbon-based polymer membrane is used as an electrolyte membrane to form a membrane-electrode assembly, the transfer of the electrode is not easily performed due to the decrease in miscibility with the electrode catalyst layer containing Nafion, a fluorine-based polymer, as a binder. Even when the membrane-electrode assembly is constructed, the bonding strength is weak, so that the resistance may increase due to the detachment between the interfaces or the driving may not be possible for a long time. Therefore, an electrolyte membrane prepared by mixing polyvinylidene fluoride (PVDF), which is a fluorine-based polymer, was used as an attempt to improve the interfacial characteristics of the electrode and the electrolyte membrane. However, the electrolyte membrane was formed by adding PVDF lacking ion conductivity. There is a problem that the overall ion conductivity decreases.

On the other hand, perfluoro-based membranes (Nafion, etc.), which are electrolyte membranes, account for a large portion of the price increase of polymer electrolyte membrane fuel cells (PEMFC), and many kinds of hydrocarbon-based electrolyte membranes are under research and development. It is known to exhibit characteristics close to the perfluorine material in terms of performance and durability. However, hydrocarbon-based polymer electrolyte membranes have a problem in that desorption with the electrode layer is serious in use. The ionomer of the electrode layer is perfluorinated, and unlike the electrolyte membrane, the ionomer of the electrode layer is very difficult to use as an ionomer because the gas permeability of the hydrocarbon-based material is very low, and even though the hydrocarbon-based polymer electrolyte membrane is applied, the ionomer of the electrode layer is perfluorinated. Although the material is more realistic, in this case, performance is initially achieved in the fuel cell operating environment, but gradually the interface between the hydrocarbon-based polymer electrolyte membrane and the electrode layer containing the perfluorinated ionomer is exposed to repeated temperature and humidity changes. There is a disadvantage in that desorption occurs and the performance and durability are greatly reduced.

In order to solve this problem, Japanese Patent Laid-Open Publication No. 5144023 and Korean Laid-Open Patent Publication No. 10-2016-0080778 use hydrocarbon-based and fluorine-based polymers to improve the bonding strength of the membrane-electrode assembly or to maintain water retention, drainage, and Although a technique for maintaining water repellency has been disclosed, there is still no sufficient improvement in the adhesion of the membrane-electrode interface.

The present invention was developed to solve the above problems, the interface between the hydrocarbon-based polymer electrolyte membrane and the catalyst layer containing the perfluorinated ionomer (eg, Nafion), the interface is detached during operation of the fuel cell due to lack of compatibility (compatability) It aims to overcome the problem.

In addition, a membrane-electrode assembly (MEA) having such an improved interfacial adhesion layer and a polymer electrolyte membrane fuel cell (PEMFC) or direct methanol fuel cell (DMFC) having the same To provide.

In the present invention, in order to solve the above problems, in the fuel cell membrane-electrode interface adhesive layer composed of a mixture of a hydrocarbon-based polymer and a fluorine-based polymer, the membrane-electrode interface adhesive layer is a composition gradient of the hydrocarbon-based polymer and the fluorine-based polymer in the thickness direction ( A film-electrode interfacial adhesive layer having a composition gradient is provided.

In addition, an ion conductive membrane containing a hydrocarbon-based polymer; A membrane-electrode interface adhesive layer for a fuel cell having a composition gradient of a hydrocarbon-based polymer and a fluorine-based polymer in a thickness direction formed on both sides of the ion conductive membrane; And a membrane-electrode assembly (MEA) having an electrode layer including a fluorine-based polymer as a binder transferred through the membrane-electrode interface adhesive layer for fuel cells, and a polymer electrolyte membrane fuel including the same. cell (PEMFC) or direct methanol fuel cell (DMFC).

According to the present invention, there is a great advantage to overcome the problem that the interface detaches during operation of the fuel cell due to lack of compatibility between the hydrocarbon-based polymer electrolyte membrane and the catalyst layer containing the perfluorinated ionomer (eg, Nafion). have.

In addition, there is an advantage that the catalyst layer transfer can be easily performed at a lower temperature and pressure by making the surface of the hydrocarbon-based electrolyte membrane more flexible during the decal process for manufacturing the membrane-electrode assembly (MEA).

In addition, the membrane-electrode assembly according to the present invention prevents an increase in interfacial resistance and desorption due to a decrease in bonding strength due to poor compatibility with a fluorine-based polymer binder when an electrolyte membrane formed of an ion conductive hydrocarbon-based polymer is used. Membrane-electrode assembly with improved durability can be usefully used in fuel cells.

In addition, by providing an ion conduction channel between the catalyst layer and the electrolyte membrane effectively by reducing the space between the electrolyte membrane and the catalyst layer to bond more closely, the performance of the MEA can be further improved when driving the fuel cell.

1 is a process chart showing a film manufacturing process using a bonding layer having a composition gradient according to an embodiment of the present invention.

2 is an optical camera photograph of a film having a compositional gradient in accordance with one embodiment of the present invention.

3 is a scanning electron microscope (SEM) photograph showing a cross-sectional structure of a film having a composition gradient and a film-electrode assembly using the same according to an embodiment of the present invention.

4 shows a polarization curve of a film having a composition gradient according to an embodiment of the present invention.

Figure 5 illustrates the results of the boiling water acceleration experiment of the membrane having a composition gradient according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail. The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

The present invention blocks the increase in interfacial resistance and desorption phenomena due to a decrease in bonding strength due to poor miscibility with the fluorine-based polymer binder in the case of using an electrolyte membrane formed of an ion conductive hydrocarbon-based polymer in a conventional membrane-electrode assembly. It is for improving durability. Specifically, in the membrane-electrode interfacial adhesion layer for a fuel cell composed of a mixture of a hydrocarbon-based polymer and a fluorine-based polymer, the membrane-electrode interfacial adhesion layer is a fuel having a composition gradient of the hydrocarbon-based polymer and the fluorine-based polymer in the thickness direction A battery film-electrode interface adhesive layer is provided.

In the fuel cell membrane-electrode interface adhesive layer according to an embodiment of the present invention, the membrane-electrode interface adhesive layer has a composition gradient by stacking a composition having different mixing ratios of hydrocarbon-based polymers and fluorine-based polymers in multiple layers. You can do that.

More specifically, the membrane-electrode interfacial adhesive layer having a composition gradient by laminating in multiple layers is prepared by n-type compositions having different mixing ratios, and then sequentially laminated so as to have a desired composition gradient, and then compressed by film-compression or the like. The electrode interface adhesive layer may be prepared or compositions having different mixing ratios may be sequentially sprayed to have a membrane-electrode interface adhesive layer having a multi-layer composition gradient.

That is, n kinds of compositions having different mixing ratios may be prepared to have various composition gradients through the composition ratio combination of the mixtures selected from them. When n, which is a mixing ratio of different compositions, is 2, for example, a mixing ratio of a hydrocarbon polymer and a fluorine polymer is 9: 1 and 1: 9, 2: 8 and 8: 2, 3: 7 and 7: 3, 4: 9: 1/1: 9, 2: 8/8: 2, 3: 7/7: 3, 4: 6/6: 4 prepared from various compositions having different mixing ratios of 6 and 6: 4 Two layers of the film-electrode interface adhesive layer having a composition gradient of two levels of phosphorus may be configured in four forms. Of course, if necessary, the combination of 9: 1/8: 2, 9: 1/7: 3, 9: 1/6: 4, or 2: 8/7: 3, 2: 8/6: 4 Two layer membrane-electrode interfacial adhesive layers with a compositional gradient of steps are also possible.

In addition, when n, which is a different mixing ratio, is 3, for example, the mixing ratio of the hydrocarbon-based polymer and the fluorine-based polymer is 3: 5, 5: 5, 7: 3. And a fluorine-based polymer may form a three-layer film-electrode interface adhesive layer having a three-step compositional gradient of 3: 5/5: 5/7: 3.

On the other hand, in another case where the different mixing ratio n is 3, the mixing ratio of the hydrocarbon polymer and the fluorine polymer is 9: 1, 2: 8, 3: 7 and 3: 7, 8: 2, 1: 9 or The mixing ratio of hydrocarbon polymer and fluorine polymer is 9: 1/2: 8 using various compositions having different mixing ratios of 9: 1, 3: 7, 4: 6 and 6: 4, 7: 3, 1: 9. The composition gradient of six steps of / 3: 7/7: 3/8: 2/9: 1 or 9: 1/3: 7/4: 6/6: 4/7: 3/1: 9 A film-electrode interface adhesive layer can be formed.

In the membrane-electrode interfacial adhesive layer for a fuel cell according to an embodiment of the present invention, the membrane-electrode interfacial adhesive layer is laminated in a multi-layer after film forming a composition having a different mixing ratio of hydrocarbon-based polymer and fluorine-based polymer or different mixing ratio The composition may be coated in multiple layers by a spray coating method.

When the film is laminated in multiple layers after molding, the thickness may be even thicker. Therefore, in the case of manufacturing a thin adhesive layer, a spray coating method is more preferable, and the adhesive layer has a fluorine-based hydrocarbon polymer having no ion conductivity other than the ion conductive polymer constituting the electrolyte membrane. Since the thickness of the bonding layer is formed to increase the ion conductivity of the entire membrane can be reduced. Therefore, the adhesive layer is preferably formed as thin as possible. However, when the thickness of the bonding layer is less than 50 nm, it may be difficult to achieve the desired improvement in adhesion between the membrane and the electrode catalyst layer, and when the thickness exceeds 1,000 nm, the battery manufactured by reducing the ion conductivity in the membrane. Can cause a decrease in performance.

In spray coating, a solution obtained by dissolving a hydrocarbon-based polymer and a fluorine-based polymer in a solvent may be formed by applying a spray. In the membrane-electrode assembly of the present invention, the bonding layer is thin and uniformly formed at a constant thickness over the entire interface between the electrolyte membrane and the electrode layer. Therefore, a mixed solution of a hydrocarbon-based polymer and a fluorine-based polymer may be prepared and evenly applied to the entire surface of the electrolyte membrane with a spray. In this case, the solvent may be used without limitation as long as it is a solvent capable of dissolving both the hydrocarbon-based polymer and the fluorine-based polymer.

Meanwhile, as described above, in the mixing of the hydrocarbon-based polymer and the fluorine-based polymer, a predetermined mixing ratio is prepared, and then a film is formed using the prepared composition and laminated after film forming, or the composition is coated in a multilayer by spray method. Although the electrode interfacial adhesive layer may be formed, a more effective compositional gradient may be achieved by using a mixing nozzle capable of simultaneously controlling the amount of electrolyte supply and mixing them through a nozzle having a hydrocarbon polymer and a fluorine polymer separately. It is also possible to use a method of supplying a mixed composition having a composition gradient to form it in the form of a film or coating in multiple layers by a spray method.

On the other hand, in the case of laminating films in multiple layers or coating in multiple layers by the spray method, the membrane-electrode assembly first laminates films of different compositions to increase the adhesive strength of the interface between the films to increase the crimping temperature during a process such as pressing. As it increases or increases the time of compression, the predetermined nonflammable and stepwise gradient initially set by diffusion of the polymer between layers of different compositions gradually changes to a gradient of continuous composition. In particular, in the case of spray coating, the predetermined compositional gradient of the first sprayed layer is more prone to a subsequent compositional gradient with the compositional gradient of the later sprayed layer. Therefore, in the manufacture of a layer having a compositional gradient, a method of coating compositions having different compositions with a spray method rather than constructing a film having a predetermined composition in multiple layers to have a compositional gradient is more continuous. It is more preferable for the adhesive force improvement.

In the membrane-electrode interfacial adhesive layer for a fuel cell according to an embodiment of the present invention, the membrane-electrode interfacial adhesive layer has a high content of a hydrocarbon-based electrolyte in contact with the hydrocarbon-based polymer in the thickness direction, and the contact portion with the electrode is a fluorine-based polymer. The content of is high, and the middle portion between them may have a composition gradient gradually changing.

In the membrane-electrode interfacial adhesion layer for a fuel cell according to an embodiment of the present invention, the hydrocarbon-based polymer and the contact portion are composed of a hydrocarbon-based polymer and a fluorine-based polymer in a weight ratio of 9: 1 to 7: 3, and the contact portion with the electrode The composition of the silver hydrocarbon-based polymer and the fluorine-based polymer is 1: 9 to 3: 7 by weight, and the middle portion may have a composition gradient gradually changing.

More specifically, the hydrocarbon-based polymer and the contacting part are prepared in a weight ratio of 9: 1 hydrocarbon-based polymer and the fluorine-based polymer in a weight ratio, and the electrode and the contact part are the mixed solution of the hydrocarbon-based polymer and fluorine-based polymer in a weight ratio of 1: 9. To prepare, the middle portion is a gradually changing composition by sequentially spray coating the mixed solution mixed in a different weight ratio on the hydrocarbon-based polymer using a mixed solution mixed in a weight ratio of 7: 3, 5: 5, 3: 7 A film-electrode interface adhesive layer having a composition gradient can be prepared.

In the membrane-electrode interfacial adhesion layer for a fuel cell according to an embodiment of the present invention, the hydrocarbon-based polymer is a sulfonated poly (arylene ether sulfone) copolymer (SPAES), sulfonated Sulfonated poly (ether ketone) copolymers (SPEK), sulfonated polyimide copolymers (SPI), sulfonated polysulfone copolymers (SPS), Sulfonated polyphenylene copolymer (SPP), sulfonated poly (arylene sulfide sulfone) copolymer (SPASS), sulfonated poly (benzimidazole ( and block copolymers including sulfonated Polybenzimidazole (SPBI), sulfonated Poly (benzoxazole); SPBO, and combinations thereof.

In the membrane-electrode interface adhesive layer for a fuel cell according to an embodiment of the present invention, the fluorine-based polymer is polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polytetrafluoroethylene ( polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP), polyvinylidene fluoride hexafluoropropylene copolymer (Poly (vinylidene fluoride-co-hexafluoropropylene; PVDF-HFP), perfluorinated ionomer (perfluorinated ionomers), or mixtures thereof.

In addition, the present invention is an ion conductive membrane containing a hydrocarbon-based polymer; A fluorine-based binder is transferred through a membrane-electrode interface adhesive layer for fuel cells having a composition gradient of a hydrocarbon-based polymer and a fluorine-based polymer in a thickness direction formed on both sides of the ion conductive membrane and the membrane-electrode interface adhesive layer for the fuel cell. A membrane-electrode assembly (MEA) having an electrode layer comprising a polymer is provided.

In addition, the present invention is a membrane-electrode assembly (MEA) having a membrane-electrode interfacial adhesive layer for a fuel cell having the composition gradient (composition gradient) and a polymer electrolyte membrane fuel cell having the same; PEMFC) or direct methanol fuel cell (DMFC).

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present disclosure. In particular, the technical spirit of the present invention and its core configuration and operation are not limited by this. In addition, the content of the present invention may be implemented in various other forms of equipment, and is not limited to the embodiments and embodiments described herein.

Preparation Example 1 Substance

As a substance used in the synthesis of sulfonated poly (arylene ether sulfone) (SPAES), biphenol (BP) was purchased from TCI, and dichloro diphenyl sulfone: DCDPS) was purchased from Solvay Advanced Polymers. Sulfonated dichloro diphenyl sulfone (SDCDPS) was prepared by using DCDPS 65% fuming sulfuric acid (Merck). Each monomer was recrystallized from isopropyl alcohol (IPA, Samchun Chemical), and used as a solvent, N-methyl-2-pyrrolidone (NMP, Junsei), anhydrous toluene ( anhydrous toluene, Aldrich) was used. Anhydrous potassium carbonate (anhydrous potassium carbonate: K ₂ CO ₃ , Aldrich) used as a catalyst was used after drying for 24 hours in a vacuum oven at 80 ℃.

The solution for the preparation of the gradient bonding layer (gradient bonding layer) used synthetic SPAES synthesized 40% sulfonated, Nafion-dispersion solution D1021 purchased from Du Pont using a spray-dryer It was used to dry again, and NMP was used as a solvent.

Materials for preparing the catalyst include Tanaka's Pt / C (Pt 37.7%), deionized water (DIwater, ELGA Pure Lab Classic), isopropyl alcohol (IPA, Samchun Chemical) and 5 wt% Nafion dispersion solution (Dupont Inc) was used.

Preparation Example 2 Synthesis of Sulfonated Poly (Arylene Ether Sulfon) (SPAES)

Sulfonated poly (arylene ether sulfone): SPAES was prepared according to Scheme 1 below.

<Scheme 1>

Sulfonated poly (arylene ether sulfone) (SPAES) is a monomer that contains biphenol (BP, TCI) and dichloro diphenyl sulfone (DCDPS, Solvay Advanced Polymers). DCDPS was prepared by using sulfonated dichloro diphenyl sulfone (SDCDPS) using 65% fuming sulfuric acid (Merck). Each monomer was used after recrystallization in isopropyl alcohol (IPA, Samchun Chemical). N-methyl-2-pyrrolidone (NMP, Junsei), anhydrous toluene (Aldrich) was used as a solvent, and anhydrous potassium carbonate (K2CO3, Aldrich) was used. Synthesis was carried out using as a catalyst.

More detailed manufacturing method is as follows. In a four-necked round flask, a gas sparge tube, Dean-stark trap condenser and stirrer are installed to create an Ar atmosphere. Then, biphenol and K ₂ CO ₃ were put, NMP and toluene were heated and stirred at 150 ° C. for 2 hours, and then heated up to 160 ° C. to toluene was refluxed for 4 hours to remove water. After the addition of SDCDPS and DCDPS, the reaction proceeds while stirring at 175 ℃ for 25 hours. SPAES 40 (sulfonation degree 40%) to prepare a 16wt% polymer solution in the solvent NMP, using a doctor blade (doctor blade) to make a film on a glass plate and dried in an oven at 80 ℃ 3 hours to complete the film.

The crude membrane (gradient membrane) using a bonding layer having a compositional gradient: Preparation 3

1 is a process chart showing a film manufacturing process using a bonding layer having a composition gradient according to an embodiment of the present invention, Figure 2 is an optical camera photograph of a film having a composition gradient according to an embodiment of the present invention.

After dissolving SPAES40 and Nafion D1021 powder (Du Pont) in NMP at 5 wt% in NMP, the ratio of the two solutions (SPAES40: Nafion weight ratio = 3: 7, 5: 5, 7: 3) or (SPAES40: Nafion weight ratio = 1: 9, 3: 7, 5: 5, 7: 3, 9: 1) Thereafter, the SPAES 40 film is fixed to the substrate at 80 ° C., and the SPAES40 is applied in the thickness direction from the film in the order of the highest.

Preparation Example 4 Gradient Membrane Characterization

T-peel strength was measured by using a universal testing machine (LR5K, LLOYD instrument) to indirectly determine the bonding strength of the membrane and the fluorine-based electrode layer prepared in Preparation Example 3. Cut the G-layer membrane and Nafion 212 membrane into 1cm x 5cm size, overlap the two membranes, and add 1cm x 4cm polyimide. Thereafter, the two membranes are bonded by hot pressing under the same conditions as in the preparation of the MEA of Preparation Example 5, and then the upper and lower ends of the two membranes are grasped by the UTM apparatus, and the binding force is measured. Hydrogen ion conductivity measurement was performed according to the change in temperature and humidity, and the conductivity was measured while raising the temperature at 100 ° C and 25 ° C and 40 ° C and 55 ° C and 70 ° C. The electrolyte membrane was prepared in a dried state and measured using an Impedence / Gain-phase analyzer (solartron-1280, Solartron).

Preparation Example 5 Composition Gradient A membrane electrode assembly using a film with a bonding layer (composition gradient membarane) (Membrane electrode assemblies: MEA) produced

Using a catalyst layer coated on a polyimide and a membrane prepared in Preparation Example 2 using a hot pressing system (CNL energy) at a temperature of 140 ° C., 200 kgf / cm ² and a pressure of 10 Prepared by applying thermal compression for minutes.

Preparation Example 6 MEA Characterization

SEM (VEGA3, TESCAN) or SEM (MIRA3, TESCAN) were used to observe the surface and the cross section of the membranes and MEAs of Preparation Examples 3 and 5. Using the MEA of Preparation Example 5, the cell test may be performed using a PEMFC test station (Fuel Cell Technologies, Inc). The active surface area of the test is 25 cm ² , and the temperature is 70 ° C. and the relative humidity is maintained at 100%. After activating the membrane, measure the performance with a change of 0.05V per 25 seconds from 1.0V to 0.3V to obtain an IV curve. To measure the resistance of the MEA, measure with EIS measurement (Biologic, SP-300). In addition, accelerated interfacial desorption experiments were conducted in boiling water to predict the durability of MEA.

Example 1 Properties of Gradient Membranes

As a result of the T-peel strength measured in Preparation Example 4, the result of the membrane laminated with the composition of the conventional hydrocarbon system (BPSH-40) and 70:30, 50:50, 30:70 is 20mN / cm ² and A value of 140 mN / cm ² was obtained. In addition, the ionic conductivity of the membrane having a compositional gradient (gradienet membrane) can be seen that the median value of BPSH-40 and Nafion for each temperature as shown in Table 1 below. This is due to the electrolyte in the sprayed membrane, which has two intermediate values.

Proton condictivity (s / cm) 25 ℃ 40 ℃ 55 ℃ 70 ℃ BPSH-40 0.0538 0.0691 0.0907 0.1132 Nafion 0.0682 0.0885 0.1190 0.1487 Gradient membrane 0.0560 0.0791 0.1050 0.1370

Example 2 Properties of MEA Using a Gradient Membrane

3 is a SEM photograph showing a cross-sectional structure of a film having a composition gradient and a film-electrode assembly using the same according to an embodiment of the present invention. (a) is a cross-sectional structure of a gradient membrane having a composition gradient of Preparation Example 3 and (b) shows a cross-sectional structure of a membrane-electrode assembly (MEA) in SEM.

The SEM image measured with Preparation Example 5 showed a binding picture of the MEA bonded to the cross section of the composition gradient membrane (gradient membrane). In order to make the layer clearly visible, 3 layers of 2um each were stacked to 6um, and the cushion role between the membrane and the electrode layer when combined with MEA can be observed.

Figure 4 shows the polarization curve of the composition gradient membrane (gradient membrane) according to an embodiment of the present invention.

In performance evaluation, 850mA / cm ² was obtained as a result of Pristine BPSH-40 at 0.6V, and 964mA / cm ² was obtained for a gradient membrane having a composition gradient. This indicates that the bonding layer fills the void space between the film and the interface, which helps to improve performance. The resistance of the membrane using the EIS was measured to be 73 ohm / cm ² for the SPAES-40 and 111 ohm / cm ² for the gradient film.

Figure 5 illustrates the results of the boiling water acceleration experiment of the membrane having a composition gradient according to an embodiment of the present invention.

As a result of the boiling water acceleration experiment, the existing SPAES-40 shows that the electrode layer is detached after 1 hour, but the gradient membrane of the composition shows that the electrode is maintained even after 3 hours. have. And, considering the amount of catalyst remaining on the transfer paper, it can be seen that a gradient membrane having a composition gradient is better transferred under the same conditions.

Claims (10)

In the fuel cell membrane-electrode interface adhesive layer composed of a mixture of a hydrocarbon-based polymer and a fluorine-based polymer, The membrane-electrode interface adhesive layer has a composition gradient of a hydrocarbon-based polymer and a fluorine-based polymer in a thickness direction. The method according to claim 1, The membrane-electrode interfacial adhesive layer is a fuel cell membrane-electrode interfacial adhesive layer, characterized in that it has a composition gradient (composition gradient) by having a multi-layer composition having different mixing ratios of hydrocarbon-based polymer and fluorine-based polymer. The method according to claim 2, The membrane-electrode interfacial adhesive layer is a fuel cell membrane, characterized in that the composition of the mixture of the hydrocarbon-based polymer and the fluorine-based polymer is laminated in a multi-layer after film molding or the composition having a different mixing ratio in a multi-layer coating by spray coating method- Electrode interface adhesive layer. The method according to claim 1, The membrane-electrode interface adhesive layer has a high content of a hydrocarbon-based electrolyte in a contact portion with a hydrocarbon-based polymer in a thickness direction, a high content of a fluorine-based polymer in an electrode and a contact portion, and an intermediate portion therebetween gradually changes in composition. A membrane-electrode interface adhesive layer for a fuel cell, characterized in that it has a gradient). The method according to claim 4, The hydrocarbon-based polymer and the contact portion may have a weight ratio of 9: 1 to 7: 3 of the hydrocarbon-based polymer and the fluorine-based polymer, and the electrode and the contact portion may have a weight ratio of 1: 9-3: 3. 7. The fuel cell membrane-electrode interface adhesive layer, wherein the middle portion has a composition gradient gradually changing. The method according to claim 1, The hydrocarbon polymer may be a sulfonated poly (arylene ether sulfone) copolymer (SPAES), a sulfonated poly (ether ketone) copolymer (SPEK) ), Sulfonated polyimide copolymer (SPI), sulfonated polysulfone copolymer (SPS), sulfonated polyphenylene copolymer (SPP), sulfonated Sulfonated poly (arylene sulfide sulfone) copolymer (SPASS), sulfonated Polybenzimidazole (SPBI), sulfonated Poly (benzoxazole) A membrane-electrode interfacial adhesion layer for a fuel cell, characterized in that it is selected from the group consisting of block copolymers comprising SPBO) and combinations thereof. The method according to claim 1, The fluorine-based polymer is polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP) , Polyvinylidene fluoride hexafluoropropylene copolymer (Poly (vinylidene fluoride-co-hexafluoropropylene; PVDF-HFP), perfluorinated ionomer, or a mixture thereof) . Ion conductive membranes containing hydrocarbon-based polymers; The fuel cell membrane-electrode interface adhesive layer according to any one of claims 1 to 7 formed on both surfaces of the ion conductive membrane; And Membrane-electrode assembly (MEA) characterized in that it comprises an electrode layer containing a fluorine-based polymer as a binder transferred via the membrane-electrode interface adhesive layer for fuel cells. A fuel cell comprising the membrane-electrode assembly according to claim 8. The method according to claim 9, The fuel cell is any one of a polymer electrolyte membrane fuel cell (PEMFC) or a direct methanol fuel cell (DMFC).

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