KR20200065611A - Catalyst composition for fuel cell, manufacturing method for the same, catalyst layer for fuel cell and membrane eletrode assembly - Google Patents

Abstract

The present specification relates to a catalyst composition for a fuel cell, a manufacturing method thereof, a catalyst layer for a fuel cell, and a membrane-electrode assembly. The catalyst composition comprises an ionomer, a catalyst, and a cellulose fiber, and crack does not occur in a catalyst layer even if an excessive amount of catalyst is contained.

Description

Catalyst composition for fuel cell, manufacturing method thereof, catalyst layer and membrane-electrode assembly for fuel cell {CATALYST COMPOSITION FOR FUEL CELL, MANUFACTURING METHOD FOR THE SAME, CATALYST LAYER FOR FUEL CELL AND MEMBRANE ELETRODE ASSEMBLY}

The present specification relates to a catalyst composition for a fuel cell, a manufacturing method thereof, a catalyst layer for a fuel cell, and a membrane-electrode assembly.

When preparing an electrode for a fuel cell, a catalyst supported on carbon having a high surface area, such as acetylene black or ketjen black, has a problem of cracking and deteriorating performance unless excessive electrode ionomer is added. Particularly, when a catalyst layer having a loading amount of 0.4 mg/cm ² or more is prepared, this problem is remarkable. To solve this, a lot of electrode ionomers may be added, but in this case, there is a problem in that performance is reduced by blocking pores in the electrode.

Korean Patent Publication 10-2014-0128329

The present specification relates to a catalyst composition for a fuel cell, a manufacturing method thereof, a catalyst layer for a fuel cell, and a membrane-electrode assembly.

This specification is an ionomer; catalyst; And it comprises a cellulose fiber (fiber), the weight ratio of the cellulose fiber to 100 parts by weight of the catalyst provides a catalyst composition for a fuel cell of 1% by weight or more and 10% by weight or less.

In addition, the present specification is a step of preparing a cellulose fiber (fiber); Mixing the cellulose fiber and ionomer; Adding a catalyst to the mixture; And it provides a method for producing a catalyst composition for a fuel cell described above comprising the step of ultrasonic treatment.

In addition, the present specification provides a catalyst layer for a fuel cell that includes the catalyst composition for a fuel cell described above.

In addition, the present specification is a cathode catalyst layer; Anode catalyst layer; And an electrolyte membrane provided between the cathode catalyst layer and the anode catalyst layer, wherein at least one of the cathode catalyst layer and the anode catalyst layer is a catalyst layer for a fuel cell described above.

The catalyst composition for a fuel cell according to an exemplary embodiment of the present specification and the fuel cell catalyst layer manufactured using the same include cellulose fibers in a specific content, and even if the catalyst is excessively contained, cracks do not occur in the catalyst layer.

1 is a schematic view showing the principle of electricity generation in a fuel cell.
2 is a view schematically showing the structure of a membrane electrode assembly.
3 is a view schematically showing an embodiment of a fuel cell.
4 is a view showing the results according to the experimental example.

Hereinafter, the present specification will be described in detail.

This specification is an ionomer; catalyst; And it comprises a cellulose fiber (fiber), the weight ratio of the cellulose fiber to 100 parts by weight of the catalyst provides a catalyst composition for a fuel cell of 1% by weight or more and 10% by weight or less.

The catalyst composition for the fuel cell includes cellulose fibers in a specific content, thereby preventing cracking of the catalyst layer that may occur when the catalyst is excessively included. When the catalyst is excessively contained, the agglomerated and non-agglomerated portions are opened due to the agglomeration between catalysts in the catalyst layer. In the case of containing cellulose fibers, since the cellulose fibers have a long shape in a certain direction, cracks are formed in the catalyst layer. It can be prevented from occurring.

In addition, since the cellulose fiber can be stably dispersed in a nano size, it is possible to improve the current density of the catalyst layer. Specifically, the cellulose fiber may include a sulfonic acid group or a hydroxy group on the surface, and the dispersibility for the solvent may be improved because the groups have high affinity with a solvent included in the composition.

In the present specification, by controlling the content of the cellulose fiber, it is possible to increase the above-described performance. In addition, the content of the cellulose fiber can be calculated based on the catalyst, the composition as a whole, or ionomer, and the description is as follows.

In one embodiment of the present specification, the weight ratio of the cellulose fiber to 100 parts by weight of the catalyst is 1% by weight or more and 10% by weight or less, more preferably 6% by weight or more and 9% by weight or less, more preferably 7% by weight % Or more and 9% by weight or less.

In one embodiment of the present specification, the weight ratio of the cellulose fiber to 100 parts by weight of the ionomer is 5% by weight or more and 23% by weight or less, more preferably 10% by weight or more and 20% by weight or less, more preferably 15% by weight % Or more and 20% by weight or less.

In one embodiment of the present specification, the weight ratio of the cellulose fiber to 100 parts by weight of the total catalyst composition for the fuel cell is 0.1% by weight or more and 15% by weight or less, preferably 0.15% by weight or more and 10% by weight or less, more preferably May be 0.2% by weight or more and 5% by weight or less. When the content of cellulose fibers is in the above range, the viscosity can be adjusted to improve the coating properties of the composition, the dispersibility in the composition can be increased, and effectively prevent the occurrence of cracks in the catalyst layer when manufacturing the catalyst layer. can do. In addition, excellent catalyst performance can be secured by reducing the oxygen diffusion resistance.

In one embodiment of the present specification, the aspect ratio of the cellulose fiber (fiber) may be 50 or more and 200 or less, preferably 50 or more and 150 or less, and more preferably 50 or more and 100 or less. When the above numerical range is satisfied, stable dispersion of the cellulose fiber into the catalyst composition is possible, thereby improving the current density of the catalyst layer. The aspect ratio is the ratio of the shortest shaft diameter to the longest shaft diameter of the cross section of the cellulose fiber.

In one embodiment of the present specification, the cellulose fiber may have a shape in which the length is longer than the width.

In one embodiment of the present disclosure, the cross-sectional area of the cellulose fibers (fiber) 20nm ² more than 32,000nm ² or less, preferably more than 30nm ² 25,000nm ² or less, and more preferably may be less than 20,000nm ² 40nm ² or more . The cross-sectional area may mean an area indicated by a cross-section in one direction of the cellulose fiber.

In an exemplary embodiment of the present specification, the average diameter of the cellulose fibers may be 2.5 nm or more and 100 nm or less, preferably 3 nm or more and 90 nm or less, and more preferably 3.6 nm or more and 80 nm or less. The average diameter may mean the longest length of the cross section in the width direction of the cellulose fiber.

When the cross-sectional area and/or the average diameter range of the cellulose fiber is satisfied, it is effective to prevent cracking of the catalyst layer.

In one embodiment of the present specification, the viscosity at 25°C of the catalyst composition for a fuel cell may be 20 cPs or more and 2,000 cPs or less, preferably 25 cPs or more and 1,800 cPs or less, and more preferably 30 cPs or more and 1,500 cPs or less. . The viscosity is measured at 25°C using a spindle 18 using a Brookfield viscometer (manufactured by Brook Field). At this time, the amount of the composition is 6.5mL to 10mL is appropriate, and to avoid exposure to light for a long time, the stabilized value is measured within 5 minutes. When the viscosity range is satisfied, coating properties are improved, and there is an advantage that the composition does not clump.

In one embodiment of the present specification, the ionomer is a fluorine polymer, a benzimidazole polymer, a polyimide polymer, a polyetherimide polymer, a polyphenylene sulfide polymer, a polysulfone polymer, a polyether sulfone polymer , Polyether ketone-based polymer, polyether-ether ketone-based polymer, and polyphenylquinoxaline-based polymer.

In one embodiment of the present specification, the weight average molecular weight of the ionomer may be 240 g/mol to 200,000 g/mol, and specifically 240 g/mol to 10,000 g/mol.

In one embodiment of the present specification, the catalyst composition for a fuel cell is 0.01 wt% or more and 6 wt% or less, 0.05 wt% or more, and 5 wt% or less, preferably 0.1 wt%, based on the total weight of the catalyst composition It may contain more than 4% by weight or less. When the content of the ionomer is within the above range, the ionomer does not overly cover the catalyst layer, facilitating the reaction of the catalyst with the fuel, while the ion transfer passage in the catalyst layer is well formed so that the movement of ions may be most smooth.

In one embodiment of the present specification, the catalyst composition for a fuel cell is one or two selected from the group consisting of water, methanol, ethanol, butanol, n-propanol, isopropanol, n-butyl acetate, ethylene glycol, dipropylene glycol and glycerol The solvent may be further included.

In one embodiment of the present specification, the solvent is 50% to 95% by weight based on the total weight of the catalyst composition, preferably 65% to 95% by weight, more preferably 75% to 95% by weight Can be When the content of the solvent in the catalyst composition is 50% by weight or more, the viscosity of the catalyst composition is prevented from being too high, so it is possible to prevent the deterioration of the particle size of the catalyst particles and the uneven formation of the catalyst layer. When the content of the solvent is 95% by weight or less, since the viscosity of the catalyst composition is prevented from being too low, the thickness of the catalyst layer is thin, thereby preventing the problem of repeating the coating several times.

In one embodiment of the present specification, as the catalyst, a catalyst in which metal is supported on the surface of the carbon support may be used.

In one embodiment of the present specification, the carbon support is not limited to this, graphite (graphite), carbon black, acetylene black, denka black, cachon black, activated carbon, mesoporous carbon, carbon nanotube, carbon One or two or more mixtures selected from the group consisting of nanofibers, carbon nanohorns, carbon nanorings, carbon nanowires, fullerenes (C60), and superP may be used.

In one embodiment of the present specification, the metal is, but is not limited to, platinum, ruthenium, osmium, platinum/ruthenium alloy, platinum/osmium alloy, platinum/palladium alloy, platinum/M alloy (M is Ga, And transition metals of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Mo, W, Rh, Ru, or combinations thereof), or combinations thereof.

In one embodiment of the present specification, the catalyst may be platinum-carrying carbon (Pt/C) or platinum-ruthenium alloy-carrying carbon (PtRu/C), preferably platinum-carrying carbon (Pt/C). . Here, the slash (/) is inserted and used together means an alloy of the metals described. For example, Pt/Ru means an alloy of platinum (Pt) and ruthenium (Ru).

In one embodiment of the present specification, the catalyst is Pt, Pt/C, Pt/Ir, Pt/Ru, Pt/W, Pt/Ni, Pt/Sn, Pt/Mo, Pt/Pd, Pt/Fe, Pt/Cr, Pt/Co, Pt/Ru/W, Pt/Ru/Mo, Pt/Ru/V, Pt/Fe/Co, Pt/Ru/Rh/Ni, Pt/Ru/Sn/W or their It may be selected from combinations.

In one embodiment of the present specification, the catalyst is 1 wt% to 20 wt%, preferably 1 wt% to 15 wt%, more preferably 5 wt% to 15 wt%, based on the total weight of the catalyst composition It may be included as. When the content of the catalyst in the catalyst composition is 1% by weight or more, the viscosity of the catalyst composition is prevented from being too low, so that the thickness of the catalyst layer is thin, thereby preventing the problem of repeating the coating several times. When the content of the catalyst is 20% by weight or less, since the viscosity of the catalyst composition is prevented from being too high, it is possible to prevent the dispersion of the catalyst particles and the uneven formation of the catalyst layer.

This specification comprises the steps of preparing a cellulose fiber (fiber); Mixing the cellulose fiber and ionomer; Adding a catalyst to the mixture; And it provides a method for producing a catalyst composition for a fuel cell described above comprising the step of ultrasonic treatment.

In one embodiment of the present specification, the step of preparing the cellulose fiber may be performed by a general method in the field to which this technology belongs. For example, the cellulose fiber may be extracted from the skin of a snail, such as a midduck or a sea urchin.

In an exemplary embodiment of the present specification, the preparing of the cellulose fiber may include decoloring the snail shell through a decoloring solution; Crushing the snail shell to obtain a powder; Acid-treating the snail shell powder; And filtering the acid-treated snail shell powder through a filter.

In one embodiment of the present specification, the decolorization solution may be a hypochlorous acid solution having a concentration of 5%.

In one embodiment of the present specification, the filter may be a filter of nylon material including pores having a diameter of 0.2 μm.

In one embodiment of the present specification, the step of acid-treating the snail shell powder may be using an acidic solution such as hydrochloric acid.

In one embodiment of the present specification, the step of mixing the cellulose fiber and the ionomer may further include mixing a solvent. That is, it may include the step of mixing a cellulose fiber, an ionomer and a solvent.

In one embodiment of the present specification, the method for preparing the catalyst composition for a fuel cell is a low temperature treatment for 10 minutes to 60 minutes at a temperature condition of 5° C. or less after the step of mixing the cellulose fibers and ionomer. It may include the steps.

In one embodiment of the present specification, the ultrasonic treatment may be performed in a tip type or a bath type.

In the present specification, the "ultrasonic treatment" refers to an act of dispersing by applying energy having a frequency of 20 kHz or more to particles, wherein the bath type has a relatively low and constant size of energy, and the tip type ( tip type) can variably apply high energy up to 50 times that of the bath type. In order to form a catalyst layer having a uniform structure, a sufficient adsorption force between the ionomer and the carbon support in the catalyst is important. If the particle diameter of the ionomer is adjusted through such ultrasonic treatment, the ionomer can be uniformly adsorbed on the carbon support in the catalyst.

In one embodiment of the present specification, an average particle diameter of the ionomer cluster (Cluster), which is a unit particle formed by aggregating ionomers after the ultrasonic treatment, may be 10 nm to 500 nm. In general, ionomers are agglomerated by electrostatic attraction to each other in a solvent to exist as aggregates having a particle diameter of 0.01 μm to 1 μm, and the unit particles formed by agglomeration of ionomers in a solvent are called ionomer clusters. When these are dispersed through ultrasonic treatment, specifically, the tip type or bath type ultrasonic treatment, most of the ionomer clusters are 10 nm to 500 nm, preferably an average of 10 nm to 300 nm. It is dispersed uniformly to have a particle size.

In one embodiment of the present specification, the tip type ultrasonic treatment is not limited to this, but may be performed for 10 minutes to 30 minutes. The bath ultrasonic treatment may be performed for 20 minutes to 120 minutes, preferably 30 minutes to 60 minutes. When the ultrasonic treatment is performed within the time range, it is possible to prevent the occurrence of localized ionomer aggregation. When it is performed in excess of the time range, the dispersion effect over time may be insignificant and may be inefficient.

In one embodiment of the present specification, the method for preparing the catalyst composition for a fuel cell may further include dispersing the catalyst composition with a high shear mixer.

In one embodiment of the present specification, the high shear mixer method is not limited to this, but is preferably performed for 15 minutes to 35 minutes at a speed of 10 m/s to 40 m/s.

The present specification provides a catalyst layer comprising the catalyst composition for a fuel cell described above. The catalyst layer may be formed from the catalyst composition for a fuel cell described above.

In one embodiment of the present specification, the catalyst layer for the fuel cell may be prepared according to a conventional method known in the art, for example, may be formed by applying and drying the catalyst composition on a gas diffusion layer. At this time, a plurality of catalyst layers may be formed by sequentially applying and drying a catalyst composition having a different ionomer content.

In one embodiment of the present specification, as a method of applying the catalyst composition on the gas diffusion layer, printing, tape casting, bar casting, slot die casting, spraying (spray), rolling (rolling), blade coating (blade coating), spin coating (spin coating), jet coating (inkjet coating) or brushing (brushing) and the like, but is not limited thereto.

In one embodiment of the present specification, the method for drying the coated catalyst composition is not particularly limited, and may be performed at a temperature of 20°C to 200°C for 10 minutes to 60 minutes.

In one embodiment of the present specification, the applied catalyst composition may be dried two or more times.

In one embodiment of the present specification, the gas diffusion layer is generally not limited as long as it is a substrate having conductivity and porosity of 80% or more, and may be made of a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt. have. The thickness of the substrate may be 30 μm to 500 μm. If the value is within the above range, the balance between mechanical strength and diffusivity of gas and water can be appropriately controlled. The gas diffusion layer may further include a microporous layer formed on one surface of the conductive substrate, and the microporous layer may include a carbon-based material and a fluorine-based resin. The microporous layer can promote the discharge of excess moisture present in the catalyst layer, thereby suppressing the occurrence of flooding.

In an exemplary embodiment of the present specification, the carbon-based material includes graphite (graphite), carbon black, acetylene black, denka black, cachon black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, and carbon nanohorns , Carbon nanorings, carbon nanowires, fullerene (C60) and one or more mixtures selected from the group consisting of super P may be used, but is not limited thereto.

In one embodiment of the present specification, the fluorine-based resin includes polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose fiber acetate, polyvinylidene fluoride-hexafluoropropylene One or two or more mixtures selected from the group consisting of copolymers (PVdF-HFP) and styrene-butadiene rubber (SBR) may be used, but are not limited thereto.

The present specification is a cellulose fiber (fiber) contained in 1 to 10% by weight based on the total weight of the catalyst layer for the fuel cell; catalyst; And it provides a catalyst layer for a fuel cell comprising an ionomer.

In one embodiment of the present specification, the cellulose fiber is 1 wt% or more and 10 wt% or less, preferably 3 wt% or more and 7 wt% or less, more preferably, based on the total weight of the catalyst layer for the fuel cell It may be 3% by weight or more and 6% by weight or less. When the cellulose fiber (fiber) is included in the numerical range, a long fiber in one direction serves to hold cracks from cracking and prevents catalysts from agglomerating to prevent the pore volume from being reduced. have. Through this, the oxygen diffusion resistance decreases, thereby increasing the current density. Conversely, if the cellulose fibers are contained in too large a quantity, the above-described effects may not appear due to the fibers being bundled together.

The present specification is a cathode catalyst layer; Anode catalyst layer; And an electrolyte membrane provided between the cathode catalyst layer and the anode catalyst layer, wherein at least one of the cathode catalyst layer and the anode catalyst layer is a catalyst layer for a fuel cell described above.

In one embodiment of the present specification, the hydrogen ion transfer resistance of at least one of the cathode catalyst layer and the anode catalyst layer is 0.2 Ω cm ² or less, 0.1 Ω cm ² or less, and preferably 0.05 Ω cm ² or less. In the case of smooth hydrogen ion transfer, there is an advantage of improving the utilization rate of the catalyst. At this time, the lower the hydrogen ion transfer resistance of the catalyst layer, the better, so the lower limit is not particularly limited.

In one embodiment of the present specification, the ohmic resistance of the membrane-electrode assembly may be 200 mΩ cm ² or less, preferably 100 mΩ cm ² or less, and more preferably 70 mΩ cm ² or less. In this case, the performance of the membrane-electrode assembly itself is improved. The ohmic resistance of the membrane-electrode assembly can be achieved by manufacturing the cathode catalyst layer or anode catalyst layer of the membrane-electrode assembly with the catalyst composition for the fuel cell described above.

In one embodiment of the present specification, the hydrogen ion conductivity (σ) of the catalyst layer may be calculated by Equation 1 below.

[Equation 1]

R=t/Aσ

In Equation 1, R is the hydrogen ion transfer resistance of the catalyst layer, t is the average thickness of the catalyst layer, and A is the area of the catalyst layer.

When the average thickness of the catalyst layer is 10 μm and the area of the catalyst layer is 25 cm ² , the hydrogen ion conductivity of the catalyst layer may be 0.02 mS cm ^{−1 or} more, and specifically, 0.03 mS cm ^{−1 or} more. In this case, there is an advantage of improving the utilization rate of the catalyst by smooth hydrogen ion transfer. At this time, the higher the hydrogen ion conductivity of the catalyst layer, the better, so the upper limit is not particularly limited.

In one embodiment of the present specification, the average thickness of the catalyst layer may be 3 μm or more and 15 μm or less, and specifically, based on 0.3 mgPt/cm ² (the weight of Pt per reference area (1 cm ² ) is 0.3 mg). It may be 5 µm or more and 12 µm or less. In this case, there is an advantage of ensuring proper porosity and hydrogen ion conductivity.

In one embodiment of the present specification, the electrolyte membrane may be a polymer electrolyte membrane.

In one embodiment of the present specification, the polymer electrolyte membrane is provided between the cathode catalyst layer and the anode catalyst layer, and the polymer contained in the polymer electrolyte membrane may be an ion conductive polymer.

In one embodiment of the present specification, the ion-conducting polymer may be a hydrocarbon-based polymer, a partially fluorine-based polymer, or a fluorine-based polymer. Specifically, the polymer electrolyte membrane may be a hydrocarbon-based polymer electrolyte membrane or a fluorine-based polymer electrolyte membrane.

In an exemplary embodiment of the present specification, the hydrocarbon-based polymer may be a hydrocarbon-based sulfonated polymer having no fluorine group, and on the contrary, the fluorine-based polymer may be a sulfonated polymer saturated with a fluorine group. The partially fluorine-based polymer may be a sulfonated polymer not saturated with a fluorine group.

In one embodiment of the present specification, the ion conductive polymer is a perfluorosulfonic acid-based polymer, a hydrocarbon-based polymer, an aromatic sulfone-based polymer, an aromatic ketone-based polymer, a polybenzimidazole-based polymer, a polystyrene-based polymer, a polyester-based polymer, Polyimide polymer, polyvinylidene fluoride polymer, polyether sulfone polymer, polyphenylene sulfide polymer, poly phenylene oxide polymer, polyphosphazene polymer, polyethylene naphthalate polymer, polyester polymer, One or two selected from the group consisting of doped polybenzimidazole polymers, polyether ketone polymers, polyether ether ketone polymers, polyphenylquinoxaline polymers, polysulfone polymers, polypyrrole polymers and polyaniline polymers It may be a polymer. The polymer may be sulfonated, and may be a single copolymer, an alternating copolymer, a random copolymer, a block copolymer, a multi-block copolymer, or a graft copolymer, but is not limited thereto.

In one embodiment of the present specification, when the polymer electrolyte membrane includes a hydrocarbon-based polymer, it may be a hydrocarbon-based polymer that is a block-type copolymer including a hydrophilic block and a hydrophobic block.

In one embodiment of the present specification, the average thickness of the polymer electrolyte membrane may be 1 μm or more and 100 μm or less.

In one embodiment of the present specification, the membrane electrode assembly has a cathode gas diffusion layer provided on an opposite side of the surface of the cathode catalyst layer provided with an electrolyte membrane, and an opposite surface of a surface of the anode catalyst layer provided with an electrolyte membrane An anode gas diffusion layer provided in may be further included.

In one embodiment of the present specification, the anode gas diffusion layer and the cathode gas diffusion layer are respectively provided on one surface of the catalyst layer, and serve as a current conductor and a passage for reaction gas and water, and have a porous structure. Therefore, the gas diffusion layer may be formed of a conductive substrate.

In one embodiment of the present specification, a conventional material known in the art may be used as the conductive substrate, for example, carbon paper, carbon cloth, or carbon felt. ) May be preferably used, but is not limited thereto.

In one embodiment of the present specification, the average thickness of the gas diffusion layer may be 100 μm or more and 500 μm or less. In this case, there is an advantage of minimizing the resistance of the reactant gas transmission through the gas diffusion layer and being in an optimal state from the viewpoint of containing adequate moisture in the gas diffusion layer.

The present specification provides a fuel cell including the membrane-electrode assembly.

FIG. 1 schematically shows the principle of electricity generation in a fuel cell. In a fuel cell, the most basic unit for generating electricity is a membrane electrode assembly (MEA), which is an electrolyte membrane M and this electrolyte membrane M It consists of an anode (A) and a cathode (C) formed on both sides of. Referring to Fig. Showing the electricity generating principle of a fuel cell 1, an anode (A) in the hydrogen or methanol, butane and the oxidation of the fuel (F) of the hydrocarbon and so on up the hydrogen ions (H ⁺⁾ and electron (e ^-), such as Occurs, and hydrogen ions move to the cathode C through the electrolyte membrane M. In the cathode C, hydrogen ions transferred through the electrolyte membrane M react with oxidizing agent O such as oxygen and electrons to generate water W. The reaction causes electron movement to occur in the external circuit.

As shown in FIG. 2, the membrane electrode assembly may include an electrolyte membrane 10 and a cathode 50 and an anode 51 positioned to face each other with the electrolyte membrane 10 interposed therebetween. Specifically, the cathode includes a cathode catalyst layer 20 sequentially provided from the electrolyte membrane 10 and a cathode gas diffusion layer 30, and the anode includes an anode catalyst layer 21 and an anode sequentially provided from the electrolyte membrane 10. A gas diffusion layer 31 may be included.

The fuel cell including the electrode catalyst layer for a fuel cell may be formed using materials and methods known in the art, except for including the electrode catalyst layer for a fuel cell described above. Referring to FIG. 3, the fuel cell is formed by including a stack 60, a fuel supply unit 80, and an oxidizing agent supply unit 70.

The stack 60 includes one or more membrane-electrode assemblies (MEAs), and when two or more membrane-electrode assemblies are included, includes a separator interposed therebetween. It prevents connection and transfers fuel and oxidant supplied from the outside to the membrane electrode assembly.

The fuel supply unit 80 serves to supply fuel to the stack, and is composed of a fuel tank 81 for storing fuel and a pump 82 for supplying fuel stored in the fuel tank 81 to the stack 60. Can be. The fuel may be gaseous or liquid hydrogen or hydrocarbon fuel, and examples of the hydrocarbon fuel include methanol, ethanol, propanol, butanol, or natural gas.

The oxidizing agent supply unit 70 serves to supply the oxidizing agent to the stack. As the oxidizing agent, oxygen is typically used, and oxygen or air may be injected into the pump 82 to be used.

Hereinafter, examples will be described in detail to specifically describe the present specification. However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art.

<Examples and Comparative Examples>

<Example 1>

<Preparation of cellulose fibers>

Nanocellulose fibers were detected in the snail shell. Specifically, the snail shell was discolored through 5% hypochlorous acid, the snail shell was pulverized to obtain a powder, and the snail shell powder was acid treated with a solution such as HCl. Subsequently, the final cellulose nanofiber was detected by filtering the acid-treated snail shell powder through a filter made of a nylon material containing pores having a diameter of 0.2 μm.

It was confirmed that an nanofiber having an aspect ratio of 50 or more was detected through an electron microscope, and a sulfonic acid group on the fiber surface can be detected through a Fourier transform infrared (FT-IR) method, 1350 cm ^-1 to ¹ 1342 cm ^-1 and 1120 cm ^-1 to 1230 cm ^-1 can be confirmed through peaks in the wavelength range.

At this time, the average diameter of the cellulose fibers was 100 nm or less, and the length was 10 µm or more.

<Production of membrane-electrode assembly>

The 3M 825 fluorine-based ionomer is dispersed by adjusting the mass ratio of 1-propanol and dipropylene glycol (DPG) solvent to 9:1, and 3 g of the extracted cellulose fiber is added thereto. Did. Thereafter, after maintaining at a low temperature of 2° C. for 30 minutes, 1 g of a TEC 10F50E catalyst sold by Tanaka was added to the solution. After ultrasonic dispersion for 1 hour, the catalyst layer composition was completed.

After casting the catalyst layer composition on a prepared polytetrafluoroethylene (PTFE) film using a doctor blade, primary drying at 35° C. for 30 minutes, and secondary drying at 140° C. for 30 minutes to finally obtain an electrode catalyst layer. It was prepared.

The membrane-electrode assembly to which the electrode catalyst layer was applied was evaluated. At this time, as the electrolyte membrane, a sulfonated polyetheretherketone-based hydrocarbon membrane was used, and a gas diffusion layer (GDL) was used as JNTG JNT30-A3, and a thickness of 280 μm to 320 μm was used. did. The compression ratio of the gas diffusion layer was set to 25%, and a glass fiber sheet gasket was used to maintain it. The active area of the membrane-electrode assembly was prepared as 25 cm ² .

<Examples 2 and 3 and Comparative Examples 1 and 2>

A membrane-electrode assembly was prepared in the same manner as in Example 1, except that the content of cellulose fibers was changed as shown in Table 1 below.

<Comparative Example 3>

A membrane-electrode assembly was prepared in the same manner as in Example 1, except that cellulose fiber was not added.

Table 1 below shows values converted based on the catalysts or ionomers of the cellulose fibers of Examples 1 to 3 and Comparative Examples 1 to 3. At this time, the weight of the catalyst was all 1 g.

Cellulose fiber content Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Catalyst standards 3wt% 6wt 9wt% 12wt% 15wt% 0 Based on ionomer 6.2wt% 12.4wt% 18.7wt% 24.9wt% 31.1wt% 0 Based on total content of catalyst layer 2wt% 3.9wt% 5.7wt% 7.5wt% 9.2wt% 0

<Experimental Example 1: I-V performance test>

The performance of the unit cells of Examples and Comparative Examples was measured using the PEMFC station equipment of Nara Cell and IV performance in a constant current mode. Specifically, the range of 0 to 1,500 mA/cm ² was measured by scanning in 100 mA/cm ² steps, and the performance was compared with the mA/cm ² value at 0.6V. The unit cell temperature was measured by operating at 70°C and relative humidity at 100% RH. The results are shown in Table 2 and FIG. 4 below.

<Experimental Example 2: Oxygen diffusion resistance performance test>

The performance of the unit cells of Examples and Comparative Examples was measured using an electrochemical impedance device (HCP-803 from Biologic). Hydrogen gas was injected at 450 mL/min on the anode side, and a mixed oxygen/nitrogen gas of 1:99 was added on the cathode side to obtain a current value reacting through a voltage scan. Based on this, the oxygen diffusion resistance value was calculated by substituting into the calculation formula described in the literature below. The oxygen diffusion resistance performance test is a measurement process described in a known literature of the Journal of electrochemical society, 158 (4) B416-B423 (2011).

MEA Experimental Example 1 Experimental Example 2 Performance (@0.6V, 100% RH)
(mA/cm ² ) Example 1 1232 219 sec/m Example 2 1312 217 sec/m Example 3 1359 210 sec/m Comparative Example 1 1092 225 sec/m Comparative Example 2 993 233 sec/m Comparative Example 3 1188 220 sec/m

From the above results, it was confirmed that when the catalyst layer contains cellulose, the performance of the catalyst layer is improved and the oxygen diffusion resistance is decreased. On the other hand, when the content of cellulose is adjusted to a certain range (Examples 1 to 3), it was confirmed that the performance is particularly good. On the other hand, it was confirmed that Comparative Examples 1 and 2 having too much cellulose content had poor performance.

Claims (15)

Ionomers;
catalyst; And
A catalyst composition for a fuel cell comprising cellulose fiber, wherein a weight ratio of the cellulose fiber to 100 parts by weight of the catalyst is 1% by weight or more and 10% by weight or less. The method according to claim 1, wherein the weight ratio of the cellulose fiber to 100 parts by weight of the ionomer is 5% by weight or more and 23% by weight or less catalyst composition for a fuel cell. The catalyst composition for a fuel cell of claim 1, wherein an aspect ratio of the cellulose fiber is 50 or more and 200 or less. The method according to claim 1, wherein the cross-sectional area of the cellulose fiber is 20nm ² to 32,000nm ² or less catalyst composition for a fuel cell. The method according to claim 1, The average diameter of the cellulose fiber is 2.5nm or more and 100nm or less catalyst composition for a fuel cell. The catalyst composition for a fuel cell according to claim 1, wherein the viscosity at 25°C is 20 cPs or more and 2,000 cPs or less. The method according to claim 1, The ionomer is a fluorine-based polymer, benzimidazole-based polymer, polyimide-based polymer, polyetherimide-based polymer, polyphenylene sulfide-based polymer, polysulfone-based polymer, polyethersulfone-based polymer, polyether ketone A catalyst composition for a fuel cell, which is a combination of one or two or more selected from the group consisting of a polymer based polymer, a polyether-ether ketone based polymer and a polyphenylquinoxaline based polymer. The method according to claim 1, Based on the total weight of the catalyst composition, the catalyst composition for a fuel cell comprising the ionomer in an amount of 0.01 wt% or more and 6 wt% or less. The method according to claim 1, The catalyst is Pt, Pt/C, Pt/Ir, Pt/Ru, Pt/W, Pt/Ni, Pt/Sn, Pt/Mo, Pt/Pd, Pt/Fe, Pt/Cr, Pt/Co, Pt/Ru/W, Pt/Ru/Mo, Pt/Ru/V, Pt/Fe/Co, Pt/Ru/Rh/Ni, Pt/Ru/Sn/W or combinations thereof The catalyst composition for a fuel cell. The method according to claim 1, Water, methanol, ethanol, butanol, n-propanol, isopropanol, n-butyl acetate, ethylene glycol, further comprising one or more solvents selected from the group consisting of dipropylene glycol and glycerol for fuel cells Catalyst composition. The catalyst composition for a fuel cell of claim 10, wherein the solvent comprises 50% by weight or more and 95% by weight or less based on the total weight of the catalyst composition. Preparing a cellulose fiber; Mixing the cellulose fiber and ionomer; Adding a catalyst to the mixture; And a method for producing a catalyst composition for a fuel cell according to any one of claims 1 to 11, which includes the steps of ultrasonic treatment. A catalyst layer for a fuel cell comprising the catalyst composition for a fuel cell according to any one of claims 1 to 9. The method according to claim 13, Cellulose fiber (fiber) contained in 1 to 10% by weight based on the total weight of the catalyst layer for the fuel cell;
catalyst; And
Catalyst layer for fuel cell containing ionomer. Cathode catalyst layer; Anode catalyst layer; And an electrolyte membrane provided between the cathode catalyst layer and the anode catalyst layer,
Membrane-electrode assembly wherein at least one of the cathode catalyst layer and the anode catalyst layer is a catalyst layer for a fuel cell according to claim 13.

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