Method for Preparing Catalyst Slurry of Fuel Cell and Method for Manufacturing Electrode

Abstract

The present disclosure relates to a method for preparing a catalyst slurry for a fuel cell that can greatly improve the utilization rate of catalyst metal and a method for manufacturing an electrode of a fuel cell using the catalyst slurry prepared by this method. Specifically, the method for preparing the catalyst slurry for the fuel cell includes: preparing a catalyst including a porous carrier and a catalyst metal; introducing the catalyst, a solvent, and an ionomer into a chamber; and allowing the ionomer to penetrate into the pores of the carrier.

Description

Technical Field

[0001] The present disclosure relates to a method for preparing a catalyst slurry for a fuel cell that can greatly improve the utilization rate of a catalyst metal, and a method for manufacturing an electrode of a fuel cell using the catalyst slurry prepared by the method. Background Art

[0002] When only a catalyst metal such as platinum (Pt) is used as a catalyst for a fuel cell, the performance is low compared to the amount of catalyst used, and the efficiency of the catalyst is reduced due to effects such as the thickness of the electrode and the distribution of pores in the electrode. Therefore, the catalyst metal is used in a state supported by carbon or metal oxide.

[0003] In order to increase the loading amount of the catalyst metal, pores are usually formed in a carrier such as carbon or metal oxide to increase the specific surface area of the carrier.

[0004] However, as described above, when a catalyst in a state where a catalyst metal is bonded to a porous carrier is used as a catalyst for an electrode of a fuel cell, the catalyst metal present in the pores of the carrier does not contact the ionomer, and thus an area where the catalyst metal cannot be used can be formed. That is, the efficiency of such a catalyst also fails to reach the expected value compared to the amount of catalyst used.

[0005] The above information disclosed in this background art section is only for enhancing the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those skilled in the art. Summary of the Invention

[0006] The present disclosure is made to solve the above problems related to the prior art.

[0007] An object of the present disclosure is to provide a method for preparing a catalyst slurry for a fuel cell that can greatly improve the utilization rate of a catalyst metal.

[0008] The object of the present disclosure is not limited to the above object. The object of the present disclosure will be clearly understood from the following description, and the object of the present disclosure can be achieved by the manner and combinations thereof defined in the claims.

[0009] In one aspect, the present disclosure provides a method for preparing a catalyst slurry for a fuel cell, the method comprising: preparing a catalyst comprising a porous carrier and a catalyst metal; introducing the catalyst, a solvent, and an ionomer into a chamber; and allowing the ionomer to penetrate into the pores of the carrier.

[0010] The carrier may include one selected from the group consisting of graphite, activated carbon, carbon black, carbon nanotubes, carbon nanofibers, carbon nanowires, and combinations thereof.

[0011] The carrier may include pores that are recessed from the outer surface of the carrier by a predetermined depth, and the pores may include pore entrances having an average diameter of 5 nm to 30 nm.

[0012] The catalyst metal may include: platinum (Pt); or an alloy of at least one or more metals selected from the group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), nickel (Ni), cobalt (Co), and yttrium (Y).

[0013] The catalyst may be introduced into the chamber, a negative pressure may be applied to the chamber, and the solvent and the ionomer may be introduced into the chamber together with an inert gas.

[0014] The solvent may include one selected from the group consisting of distilled water, ethanol, propanol, butanol, ethylene glycol, and combinations thereof.

[0015] The ionomer may include at least one selected from the group consisting of fluorine-based resins, non-fluorine-based resins, and combinations thereof, wherein the fluorine-based resin includes one or more single polymers, crosslinked polymers, graft polymers, copolymers, or blends selected from the group consisting of perfluorosulfonic acid and perfluorocarboxylic acid, and the non-fluorine-based resin includes one or more single polymers, crosslinked polymers, graft polymers, copolymers, or blends selected from the group consisting of polyarylene ether, polyether ketone, polyether ether ketone, polyethersulfone, polyether ether sulfone, polyazole, polyvinylalcohol, polyphenylene oxide, polyphenylene sulfide, polysulfone, polycarbonate, polystyrene, polyimide, polyamide, polyquinoxaline, and polybenzimidazole.

[0016] The ionomer may include a polymer having a radius of gyration of the polymer chain of 5 nm or less.

[0017] Permeating the ionomer into the pores of the support may include: stirring the contents of the chamber while applying at least one of heat and pressure to the contents of the chamber.

[0018] The temperature of the contents of the chamber can be increased to 25 °C to 80 °C.

[0019] The pressure applied to the contents of the chamber can be 2 bar to 200 bar.

[0020] An inert gas can be introduced into the chamber to apply pressure to the contents of the chamber.

[0021] The contents of the chamber can be stirred for 24 hours to 48 hours.

[0022] The catalyst metal can be bonded to the outer surface of the support and the inner surface of each pore, and the ionomer can permeate into the pores of the support and can contact the catalyst metal bonded to the inner surface of each pore of the support.

[0023] In another aspect, the present disclosure provides a method for manufacturing an electrode of a fuel cell, the method including: coating a catalyst slurry on a substrate to manufacture an electrode.

[0024] The substrate can be a release paper, including one selected from the group consisting of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and combinations thereof.

[0025] The catalyst slurry can be coated by a screen printing method, a spraying method, a coating method using a doctor blade, a gravure coating method, a dip coating method, a screen method, a painting method, or a coating method using a slot die.

[0026] The method can further include: drying the electrode at 100 °C to 200 °C for 5 minutes to 24 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other features of the present disclosure will now be described in detail with reference to some exemplary embodiments of the present disclosure shown in the drawings, where the drawings are given hereinafter only by way of illustration and thus do not limit the present disclosure, and where:

[0028] Figure 1 is a flowchart showing a method for preparing a catalyst slurry of a fuel cell according to the present disclosure;

[0029] Figure 2 is a schematic cross-sectional view showing a catalyst according to the present disclosure;

[0030] Figure 3A is a view schematically showing a complex of a catalyst and an ionomer included in a catalyst slurry prepared according to the present disclosure; and

[0031] Figure 3B is a view schematically showing a complex of a catalyst and an ionomer included in a catalyst slurry prepared by a conventional method.

[0032] It should be understood that the drawings are not necessarily drawn to scale and present a certain degree of simplified representation of various preferred features illustrating the basic principles of the present disclosure. Specific design features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and use environment.

[0033] In the drawings, throughout several views of the drawings, reference numerals refer to the same or equivalent parts of the present disclosure. Detailed Description of the Invention

[0034] From the following preferred embodiments with reference to the drawings, the above and other objects, features, and advantages will be clearly understood. However, the present disclosure is not limited to the embodiments and will be implemented in different forms. The embodiments are presented only to provide a thorough and complete understanding of the disclosed content and are sufficient to inform those skilled in the art of the technical concept of the present disclosure.

[0035] Throughout the description of the drawings, the same reference numerals refer to the same elements. In the drawings, for clarity, the dimensions of the structures are enlarged. It will be understood that although terms such as "first", "second", etc. may be used herein to describe various elements, the corresponding elements should not be understood to be limited by these terms, which are only used to distinguish one element from another. For example, within the scope defined by the present disclosure, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form.

[0036] It will be further understood that when terms such as "comprising", "having", etc. are used in this specification, they specify the presence of the stated features, quantities, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof. Additionally, it will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element may be directly on the other element, or there may also be an intermediate element. It will also be understood that when an element such as a layer, film, region, or substrate is referred to as being "under" another element, the element may be directly under the other element, or there may also be an intermediate element.

[0037] Unless otherwise clearly specified in the context, all quantities, numbers, and / or expressions representing components, reaction conditions, polymer compositions, and amounts of mixtures used in this specification are approximate values, which reflect various measurement uncertainties inherently present when obtaining these numbers, etc. For this reason, it should be understood that in all cases, the term "about" should modify all quantities, numbers, and / or expressions. Additionally, when numerical ranges are disclosed in the specification, unless otherwise limited, these ranges are continuous and include all numbers from the minimum value to the maximum value within the range, including the maximum value. Furthermore, when the range is an integer, unless otherwise limited, the range includes all integers from the minimum value to the maximum value within the range.

[0038] Figure 1 is a flowchart showing a method for preparing a catalyst slurry for a fuel cell according to the present disclosure. Referring to this figure, the method includes: preparing a catalyst including a porous support and a catalyst metal (S10); introducing the catalyst, a solvent, and an ionomer into a chamber (S20); and allowing the ionomer to penetrate into the pores of the support (S30).

[0039] Figure 2 is a schematic cross-sectional view showing a catalyst. Referring to this figure, the catalyst includes a porous support 10 having pores 11 and a catalyst metal 20. In this case, the catalyst metal 20 includes a catalyst metal 21 bonded to the outer surface of the support 10 and a catalyst metal 22 bonded to the inner surface of each pore 11.

[0040] As Figure 2 shown, as long as the support 10 is porous, the type of the support 10 is not particularly limited. For example, the support 10 may include one selected from the group consisting of graphite, activated carbon, carbon black, carbon nanotubes, carbon nanofibers, carbon nanowires, and combinations thereof.

[0041] The carbon black may include one selected from the group consisting of Ketjen black, acetylene black, furnace black, channel black, and combinations thereof.

[0042] The support 10 includes pores 11 that are recessed inward from the outer surface of the support 10 by a predetermined depth. Accordingly, each pore 11 includes a pore inlet 12 where the pore 11 is connected to the outer surface of the support 10 and an internal space formed in the pore.

[0043] The average diameter of the pore inlet 12 is not particularly limited. However, in the present disclosure, the average diameter D of the pore inlet 12 is 5 nm to 30 nm so that the ionomer can easily penetrate into the pores 11. Hereinafter, the term "pore" refers to a pore configured such that the average diameter D of the pore inlet 12 is 5 nm to 30 nm. However, this is defined for ease of description. The pores 11 according to the present disclosure should not be construed as having pore inlets 12 within the above size range.

[0044] In addition, the average diameter of the internal space of the hole 11 may be from 5 nm to 30 nm.

[0045] The catalyst metal 20 may include: platinum (Pt); or an alloy of at least one or more than two metals selected from the group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), nickel (Ni), cobalt (Co), and yttrium (Y).

[0046] Prepare the above catalyst, and introduce the catalyst, a solvent, and an ionomer into a chamber (S20).

[0047] At this time, in the present disclosure, in order to allow the ionomer to penetrate into the holes 11 of the catalyst, as described above, the catalyst is introduced into the chamber, and a negative pressure is applied to the chamber to remove gas from the holes 11 and the chamber. After removing the gas from the holes 11 and the chamber, the solvent and the ionomer are introduced into the chamber together with an inert gas such as argon.

[0048] The solvent is not particularly limited. For example, the solvent may include one selected from the group consisting of distilled water, ethanol, propanol, butanol, ethylene glycol, and combinations thereof.

[0049] The type of the ionomer is not particularly limited. For example, the ionomer may include at least one selected from the group consisting of fluorine-based resins, non-fluorine-based resins, and combinations thereof, where the fluorine-based resin includes one or more single polymers, crosslinked polymers, graft polymers, copolymers, or blends selected from the group consisting of perfluorosulfonic acid and perfluorocarboxylic acid, and the non-fluorine-based resin includes one or more single polymers, crosslinked polymers, graft polymers, copolymers, or blends selected from the group consisting of polyarylene ethers, polyether ketones, polyether ether ketones, polyether sulfones, polyether ether sulfones, polyazoles, polyvinyl alcohols, polyphenylene ethers, polyphenylene sulfides, polysulfones, polycarbonates, polystyrenes, polyimides, polyamides, polyquinoxalines, and polybenzimidazoles.

[0050] In one embodiment of the present disclosure, a polymer having a radius of gyration of a polymer chain of 5 nm or less is used as the ionomer to allow the ionomer to penetrate into the holes 11 of the catalyst. The polymer chain has a chain shape at a certain point in time when at rest, but since the polymer chain moves rapidly and continuously, the average shape of the polymer chain is a sphere or an ellipsoid. In this case, the radius of gyration of the sphere or the ellipsoid is referred to as the "radius of gyration of the polymer chain". If the radius of gyration of the polymer chain of the ionomer exceeds 5 nm, it may be difficult for the ionomer to penetrate into the holes 11. In particular, in the case where the hole 11 has a hole inlet 12 with an average diameter D of 5 nm to 30 nm, it may be even more difficult for the ionomer to penetrate into the holes 11. In the present disclosure, an ionomer having a radius of gyration of the polymer chain smaller than the average diameter D of the hole inlet 12 is used.

[0051] A catalyst, a solvent, and an ionomer are introduced into a chamber, and the ionomer is permeated into the pores 11 of the support 10 (S30). Specifically, while heating and pressurizing the contents of the chamber, the contents of the chamber are stirred so that the ionomer permeates into the pores 11.

[0052] Heat can be applied to the chamber to raise the temperature of the contents of the chamber to 25°C to 80°C, 50°C to 80°C, or 60°C to 80°C.

[0053] In addition, an inert gas such as nitrogen or argon can be introduced into the chamber so that the pressure applied to the contents of the chamber becomes 2 bar to 200 bar, 50 bar to 200 bar, or 100 bar to 200 bar.

[0054] The temperature of the contents of the chamber and the pressure applied to the contents of the chamber can be detected by a temperature sensor in the chamber.

[0055] In addition, the contents of the chamber can be stirred for 24 hours to 48 hours or 36 hours to 48 hours.

[0056] According to an embodiment of the present disclosure, when preparing a catalyst slurry including a catalyst, a solvent, and an ionomer, when stirring is performed after introducing each component into the chamber, heat and pressure are applied under the above conditions so that the ionomer permeates into the pores 11 of the support 10 included in the catalyst.

[0057] In short, in one embodiment of the present disclosure, a catalyst slurry is prepared by the following method so that the ionomer permeates into the pores 11.

[0058] First, a catalyst is introduced into the chamber, and a negative pressure is applied to the chamber to remove gas from the pores of the support 10.

[0059] In addition, a polymer having a radius of gyration of the polymer chain smaller than the average diameter of the pore inlet of the pores 11, particularly a polymer having a radius of gyration of the polymer chain of 5 nm or less, is used as the ionomer.

[0060] In addition, the catalyst, the solvent, and the ionomer are stirred within a specific temperature and pressure range.

[0061] Figure 3A is a view schematically showing a composite of a catalyst and an ionomer included in a catalyst slurry prepared according to the present disclosure. At the same time, Figure 3B is a view schematically showing a composite of a catalyst and an ionomer included in a catalyst slurry prepared by a conventional method.

[0062] Refer to Figure 3A, it can be seen that for the composite according to the present disclosure, the ionomer 30 penetrates into the pores 11 of the carrier 10 and contacts the catalyst metal 22 bound to the inner surface of the pores 11. On the other hand, from Figure 3B it can be seen that the ionomer 30 does not penetrate into the pores 11 of the carrier 10, so the catalyst metal 22 bound to the inner surface of the pores 11 cannot be utilized.

[0063] Therefore, according to the present disclosure, both the catalyst metal 21 bound to the outer surface of the carrier 10 and the catalyst metal 22 bound to the inner surface of each pore 11 can be utilized, thereby obtaining a higher catalyst utilization rate than in the conventional technology.

[0064] A method for manufacturing an electrode of a fuel cell according to the present disclosure includes: coating the catalyst slurry prepared as described above on a substrate to manufacture an electrode; and drying the electrode.

[0065] The substrate may include release paper. Specifically, the substrate may include one selected from the group consisting of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and combinations thereof.

[0066] The catalyst slurry can be coated using a screen printing method, a spraying method, a coating method using a doctor blade, a gravure coating method, a dip coating method, a screen method, a painting method, or a coating method using a slot die.

[0067] The drying conditions of the electrode are not particularly limited. For example, the electrode can be dried at 100 °C to 200 °C for 5 minutes to 24 hours.

[0068] In addition, the electrode manufactured as described above can be bonded to an electrolyte membrane using a hot pressing method to manufacture a membrane electrode assembly (MEA).

[0069] It is obvious from the above that in the case of preparing the catalyst slurry according to the present disclosure, the ionomer penetrates into the pores in the carrier, and the ionomer contacts the catalyst metal present in the pores, thereby greatly improving the utilization rate of the catalyst metal.

[0070] The effects of the present disclosure are not limited to those mentioned above. It should be understood that the effects of the present disclosure include all effects that can be inferred from the previous description of the present disclosure.

[0071] Embodiments of the present disclosure have been described with reference to the accompanying drawings. However, it will be obvious to those skilled in the art that the present disclosure can be implemented in specific forms different from those set forth herein without departing from the spirit and basic characteristics of the present disclosure. Therefore, the above embodiments should be construed as illustrative in all respects and not restrictive.

Claims

1. A method for preparing a catalyst slurry for a fuel cell, comprising: Preparing a catalyst comprising a porous support and a catalyst metal; Introducing the catalyst into a chamber, applying a negative pressure to the chamber, and introducing a solvent and an ionomer together with an inert gas into the chamber; and Allowing the ionomer to penetrate into the pores of the support, wherein the ionomer comprises a polymer having a radius of gyration of the polymer chain of 5 nm or less, wherein the support comprises pores that are recessed inward from the outer surface of the support by a predetermined depth, and the pores comprise pore entrances having an average diameter of 5 nm to 30 nm, wherein allowing the ionomer to penetrate into the pores of the support comprises: Stirring the contents of the chamber while applying heat and pressure to the contents of the chamber, wherein the pressure applied to the contents of the chamber is 2 bar to 200 bar.

2. The method according to claim 1, wherein the support comprises one selected from the group consisting of graphite, activated carbon, carbon black, carbon nanotubes, carbon nanofibers, carbon nanowires, and combinations thereof.

3. The method according to claim 1, wherein the catalyst metal comprises: an alloy of at least one or two or more metals selected from the group consisting of platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), nickel (Ni), cobalt (Co), and yttrium (Y).

4. The method according to claim 1, wherein the solvent comprises one selected from the group consisting of distilled water, ethanol, propanol, butanol, ethylene glycol, and combinations thereof.

5. The method according to claim 1, wherein the ionomer comprises at least one selected from the group consisting of fluorine-based resins, non-fluorine-based resins, and combinations thereof, the fluorine-based resin comprises one or more single polymers, crosslinked polymers, copolymers, or blends selected from the group consisting of perfluorosulfonic acid and perfluorocarboxylic acid, the non-fluorine-based resin comprises one or more single polymers, crosslinked polymers, copolymers, or blends selected from the group consisting of polyarylene ethers, polyether ketones, polyether ether ketones, polyether sulfones, polyether ether sulfones, polyazoles, polyvinyl alcohols, polyphenylene ethers, polyphenylene sulfides, polysulfones, polycarbonates, polystyrenes, polyimides, polyamides, polyquinoxalines, and polybenzimidazoles.

6. The method according to claim 1, wherein raising the temperature of the contents of the chamber to 25 °C to 80 °C.

7. The method according to claim 6, wherein the temperature of the contents of the chamber is raised to 50 °C to 80 °C, wherein the pressure applied to the contents of the chamber is 50 bar to 200 bar.

8. The method according to claim 1, wherein stirring the contents of the chamber for 24 hours to 48 hours.

9. The method according to claim 1, wherein the catalyst metal is bonded to the outer surface of the support and the inner surface of each of the pores, and the ionomer penetrates into the pores of the support and contacts the catalyst metal bonded to the inner surface of each of the pores of the support.

10. A method for manufacturing an electrode for a fuel cell, comprising: Coating the catalyst slurry prepared by the method according to claim 1 on a substrate to manufacture the electrode.

11. The method according to claim 10, wherein, the substrate is a release paper, including one selected from the group consisting of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and combinations thereof.

12. The method according to claim 10, wherein, the catalyst slurry is coated by screen printing, spraying, coating with a doctor blade, gravure coating, painting, or slot die coating.

13. The method according to claim 10, further comprising: drying the electrode at 100°C to 200°C for 5 minutes to 24 hours.

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