Electrode for fuel cell, membrane-electrode assembly comprising same, and fuel cell

Abstract

The present invention relates to an electrode for a fuel cell, a membrane-electrode assembly including same, and a fuel cell. The electrode for a fuel cell is an electrode having a multilayer structure including a laminate of a first layer and a second layer, wherein the first layer includes a carbon-based material, and the second layer includes an active metal.

Description

Electrode for a fuel cell, membrane-electrode assembly including the same, and fuel cell

[0001] The present invention relates to an electrode for a fuel cell, a membrane-electrode assembly including the same, and a fuel cell.

[0002]

[0003] A fuel cell electrochemically produces water by using hydrogen as fuel at the anode and air as fuel at the cathode. A representative example of such a fuel cell is the Polymer Electrolyte Membrane Fuel Cell (PEMFC).

[0004] Electrons move from the anode to the cathode through the electrical load, and at the cathode, oxygen combines with electrons and hydrogen cations generated from hydrogen as shown in the equation below to be reduced and produce water.

[0005] To increase the reaction rate at the above electrode (the anode and / or the cathode), a catalyst may be applied, and as such a catalyst, a Pt / C catalyst in which platinum (Pt) is supported on a carbon-based material having a large specific surface area and excellent electrical conductivity is most widely used.

[0006] However, when applying the Pt / C catalyst to the electrode, a dead area where platinum (Pt) is not activated may occur. Therefore, in order to realize a high-performance electrode, an excessive amount of Pt / C catalyst must be used, but the unit cost of the electrode increases due to the excessive use of platinum (Pt), which is a hindering factor in the commercialization of fuel cells.

[0007]

[0008] One embodiment provides an electrode for a fuel cell that can secure excellent performance of the electrode while reducing the amount of active metal used.

[0009]

[0010] One embodiment provides a fuel cell electrode having a multilayer structure comprising a laminate of a first layer and a second layer, wherein the first layer comprises a carbon-based material and the second layer comprises an active metal.

[0011] Another embodiment provides a membrane-electrode assembly including the electrode for the fuel cell, and yet another embodiment provides a fuel cell including the membrane-electrode assembly.

[0012]

[0013] The electrode according to one embodiment can secure excellent performance by increasing the activity rate while reducing the amount of active metal used.

[0014] Accordingly, by using the electrode for a fuel cell of one embodiment, a high-performance membrane-electrode assembly can be manufactured at a low cost, and the commercialization of fuel cells can be accelerated.

[0015]

[0016] FIG. 1 is a diagram briefly illustrating the membrane-electrode assembly of Comparative Example 1 and the reaction within a fuel cell containing the same.

[0017] FIG. 2 is a diagram briefly illustrating the membrane-electrode assembly of Example 1 and the reaction within a fuel cell containing the same.

[0018] FIG. 3 is a diagram briefly illustrating the membrane-electrode assembly of Example 2 and the reaction within a fuel cell containing the same.

[0019] FIG. 4 is a diagram briefly illustrating the membrane-electrode assembly of Example 3 and the reaction in a fuel cell containing the same.

[0020] FIG. 5 is a diagram briefly illustrating the membrane-electrode assembly of Example 4 and the reaction in a fuel cell containing the same.

[0021] FIG. 6 is a diagram briefly illustrating the membrane-electrode assembly of Example 5 and the reaction within a fuel cell containing the same.

[0022] FIG. 7 is a diagram briefly illustrating the membrane-electrode assembly of Example 6 and the reaction in a fuel cell containing the same.

[0023] FIG. 8 is a diagram briefly illustrating the membrane-electrode assembly of Example 7 and the reaction in a fuel cell containing the same.

[0024] FIG. 9 is a diagram briefly illustrating the membrane-electrode assembly of Example 8 and the reaction in a fuel cell containing the same.

[0025] The advantages and features of the technology described below, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the forms of implementation are not limited to the embodiments disclosed below. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise. Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0026] In addition, the singular form includes the plural form unless specifically mentioned otherwise in the phrase.

[0027]

[0028] (electrode)

[0029] One embodiment provides a fuel cell electrode having a multilayer structure comprising a laminate of a first layer and a second layer, wherein the first layer comprises a carbon-based material and the second layer comprises an active metal.

[0030]

[0031] The electrode for a fuel cell in one embodiment may be a cathode or an anode. The cathode and anode of the fuel cell, as well as both of them, may be applied as electrodes for a fuel cell in one embodiment.

[0032]

[0033] Hereinafter, an electrode for a fuel cell according to one embodiment will be described in detail.

[0034]

[0035] multilayer structure

[0036] In the reaction of a polymer electrolyte membrane fuel cell (PEMFC) as described below, the ORR reaction (cathode), which determines the rate, has a large number of 4-electron reactions and is very slow compared to the HOR reaction (anode), thus determining the overall performance of the PEMFC.

[0037] Anode: H2 -> 2H + + 2e - , E o = 0.00 V

[0038] Cathode: 1 / 2O2 + 2H + + 2e - -> H2O, E o = 1.23 V

[0039] Total: H2 + 1 / 2O2 → H2O, E o = 1.23 V

[0040]

[0041] In this regard, the electrodes for fuel cells known to date (anode and / or cathode, mainly the cathode) have a single-layer structure containing a Pt / C catalyst.

[0042] The above Pt / C catalyst has a structure in which platinum (Pt) is supported on a carbon-based material, and the position of platinum (Pt) has a major influence on the overall reaction of the aforementioned fuel cell.

[0043] For example, if two or more platinum (Pt) atoms cover each other's active surfaces, or if platinum (Pt) atoms are located in a place where there is no ion conductor (e.g., an ionomer or polymer), the active metal may not be activated, resulting in a dead area.

[0044] This can be a contributing factor to the aforementioned disadvantages, such as excessive use of platinum (Pt), increased unit costs of electrodes, and hindrance to the commercialization of fuel cells.

[0045]

[0046] On the other hand, the electrode for a fuel cell of one embodiment is not a single-layer structure containing a Pt / C catalyst, but a multi-layer structure including a first layer containing a carbon-based material and a second layer containing an active metal.

[0047] Specifically, the first layer may be a 'carbon layer' that does not contain an active metal, and the second layer may be an 'active metal layer' that does not contain a carbon-based material. By separating the carbon layer (first layer) and the active metal layer (second layer) in this way, the amount of active metal used can be reduced while increasing the activity rate, thereby ensuring excellent performance of the electrode.

[0048] Specifically, when the structure is a multilayer structure comprising a first layer containing the carbon-based material and a second layer containing an active metal, the active metal can be evenly distributed in the second layer in contact with the polymer electrolyte membrane or gas diffusion layer, thereby suppressing the dead area while increasing the activity rate of the active metal.

[0049] In addition, when the structure is a multilayer structure comprising a first layer containing the carbon-based material and a second layer containing an active metal, the step of supporting the active metal on the carbon-based material (i.e., the catalyst synthesis step) can be omitted, thereby having the advantage of simplifying the entire fabrication process leading to the electrode, membrane-electrode assembly, and fuel cell.

[0050]

[0051] In other words, the fuel cell electrode of one embodiment can reduce the amount of active metal used by about 10 to 30% within the same performance, thereby lowering the unit cost and reducing the thickness of the electrode to increase the efficiency of the fuel cell.

[0052] Accordingly, by using the electrode for a fuel cell of one embodiment, a high-performance membrane-electrode assembly can be manufactured at a low cost, and the commercialization of fuel cells can be accelerated.

[0053]

[0054] carbonaceous materials

[0055] The above carbon-based material is not particularly limited as long as it is a carbon-based material already used as a carrier in the industry.

[0056]

[0057] The above carbon-based material has a BET specific surface area of ​​0 m 2 / g exceeding 2000 m 2 Those with a value of / g or less may be used. For example, among carbon-based materials conventionally used as carriers in the industry, those with a BET specific surface area of ​​0 m 2 / g exceeding 200 m 2 Carbonaceous materials with a specific surface area of ​​200 m² or less / g 2 / g exceeding 700 m 2 Carbonaceous materials with a specific surface area of ​​700 m² or less / g or less, or BET specific surface area of ​​700 m² 2 / g exceeding 2000 m 2 Carbon-based materials with a value of 1g or less can be selected.

[0058]

[0059] The above carbon-based material may include carbon black, graphite, carbon nanofibers, graphitized carbon nanofibers, carbon nanotubes, carbon nanohorns, carbon nanowires, or a combination thereof. Carbon black may include, for example, Denka black, Ketjen black, acetylene black, channel black, furnace black, lamp black, thermal black, or a combination thereof. For example, carbon black may be used as the above carbon-based material.

[0060]

[0061] active metal

[0062] The above active metal is not particularly limited as long as it is widely used in the industry, but may include precious metals including platinum, palladium, iridium, ruthenium, and silver; non-precious metals including nickel, cobalt, and iron; or a combination thereof.

[0063]

[0064] ion conductor

[0065] The first layer containing the carbon-based material and the second layer containing the active metal may each independently further include an ion conductor, wherein the ion conductor is not particularly limited as long as it is an ion conductor conventionally used in the art. For example, the ion conductor may be an ionomer or a polymer having ion conductivity.

[0066]

[0067] Loading amount for each floor

[0068] The first layer containing the above carbon-based material has a loading amount per area of ​​the electrode of 0.05 mg / cm² 2 Exceeding 5 mg / cm² 2 Less than, or 0.1 mg / cm² 2 0 to 5 mg / cm² 2 It may be less than.

[0069]

[0070] The second layer containing the active metal has a loading amount per area of ​​the electrode of 0.05 mg / cm² 2 Exceeding 5 mg / cm² 2 Less than, or 0.1 mg / cm² 2 0 to 5 mg / cm² 2 It may be less than.

[0071]

[0072] (Membrane-electrode assembly and fuel cell)

[0073] Another embodiment provides a membrane-electrode assembly including the electrode for the fuel cell, and yet another embodiment provides a fuel cell including the membrane-electrode assembly.

[0074] The membrane-electrode assembly and the fuel cell are identical to the general membrane-electrode assembly and fuel cell for fuel cells, except that they include the electrodes described above; therefore, a detailed description is omitted.

[0075]

[0076] Specific embodiments of the invention are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the invention and should not limit the scope of the invention.

[0077]

[0078] Comparative example

[0079] FIG. 1 is a diagram briefly illustrating the membrane-electrode assembly of Comparative Example 1 and the reaction within a fuel cell containing the same.

[0080]

[0081] (1) Preparation of Pt / C catalyst

[0082] A carbon black dispersion is prepared by wet grinding a dispersion in which carbon black is dispersed in a solvent as a carbon-based material.

[0083]

[0084] Independently of this, a platinum solution is prepared.

[0085] The platinum solution is added to the carbon black dispersion, the pH is adjusted, and then dried to obtain a Pt / C catalyst.

[0086]

[0087] (2) Manufacturing of the electrode (cathode)

[0088] The above Pt / C catalyst, ion conductor, and solvent are mixed to prepare an electrode ink.

[0089] After coating the above electrode ink onto a release film, it is dried in an oven. The material layer dried on the release film can be used as an electrode (cathode).

[0090]

[0091] (3) Preparation of membrane-electrode assembly

[0092] The above electrode (cathode) is transferred onto the membrane of a separately prepared membrane-electrode (anode) assembly.

[0093] According to Comparative Example 1, it takes at least 4 days to manufacture the final membrane-electrode assembly.

[0094]

[0095] Example 1

[0096] FIG. 2 is a diagram briefly illustrating the membrane-electrode assembly of Example 1 and the reaction within a fuel cell containing the same.

[0097]

[0098] (1) Manufacturing of the electrode (cathode)

[0099] Carbon black is obtained by wet grinding carbon black dispersed in a solvent as a carbon-based material and then drying it. A carbon black dispersion in which an ion conductor and a solvent are mixed with the carbon black is coated onto a release film and then dried. The material layer dried on the release film can be referred to as the first layer (carbon layer).

[0100] Independently, a platinum solution is prepared. In the total amount of 100% by weight of the platinum solution, the platinum content may be 10 to 40% by weight (stock solution) or 1 to 10% by weight (diluted solution).

[0101] The above platinum solution is coated onto the first layer (carbon layer) and then dried. The material layer dried on the first layer (carbon layer) can be referred to as the second layer (platinum layer). Additionally, the first layer (carbon layer) and the second layer (platinum layer) sequentially stacked on the release film can be referred to as an electrode (cathode).

[0102]

[0103] (2) Preparation of membrane-electrode assembly

[0104] With the first layer (carbon layer) and the second layer (platinum layer) sequentially laminated on the above-mentioned release film, they are transferred onto the film of a separately prepared membrane-electrode (anode) assembly. Through this, a laminate having a [first layer (carbon layer) / second layer (platinum layer)](cathode) / membrane / electrode (anode) structure is obtained.

[0105] Example 1 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0106]

[0107] Example 2

[0108] FIG. 3 is a diagram briefly illustrating the membrane-electrode assembly of Example 2 and the reaction within a fuel cell containing the same.

[0109]

[0110] Fabrication of electrode (cathode) and fabrication of membrane-electrode assembly

[0111] Carbon black is obtained by wet grinding carbon black dispersed in a solvent as a carbon-based material and then drying it. A carbon black dispersion in which an ion conductor and a solvent are mixed with the carbon black is coated onto a release film and then dried in an oven. The material dried on the release film can be the first layer (carbon layer).

[0112] The above first layer (carbon layer) is transferred onto the film of a separately prepared membrane-electrode (anode) assembly. Through this, a laminate having a first layer (carbon layer) / membrane / electrode (anode) structure is obtained.

[0113] Independently, a platinum solution is prepared. In the total amount of 100% by weight of the platinum solution, the platinum content may be 10 to 40% by weight (stock solution) or 1 to 10% by weight (diluted solution).

[0114] The above platinum solution is coated onto the first layer of the laminate having the first layer (carbon layer) / membrane / electrode (anode) structure and then dried. Through this, a laminate having the [second layer (platinum layer) / first layer (carbon layer)](cathode) / membrane / electrode (anode) structure is obtained.

[0115] Example 2 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0116]

[0117] Example 3

[0118] FIG. 4 is a diagram briefly illustrating the membrane-electrode assembly of Example 3 and the reaction in a fuel cell containing the same.

[0119]

[0120] Fabrication of electrode (anode) and fabrication of membrane-electrode assembly

[0121] Carbon black is obtained by wet grinding carbon black dispersed in a solvent and then drying it. A carbon black dispersion, in which an ion conductor and a solvent are mixed with the carbon black, is coated onto a release film and then dried in an oven. The material layer dried on the release film can be referred to as the first layer (carbon layer).

[0122] Independently, a platinum solution is prepared. In the total amount of 100% by weight of the platinum solution, the platinum content may be 10 to 40% by weight (stock solution) or 1 to 10% by weight (diluted solution).

[0123] The above platinum solution is coated onto the first layer (carbon layer) and then dried. The material layer dried on the first layer (carbon layer) can be referred to as the second layer (platinum layer). Additionally, the first layer (carbon layer) and the second layer (platinum layer) sequentially stacked on the release film can be referred to as an electrode (anode).

[0124]

[0125] (2) Preparation of membrane-electrode assembly

[0126] With the first layer (carbon layer) and the second layer (platinum layer) sequentially laminated on the above-mentioned release film, they are transferred onto the film of a separately prepared membrane-electrode (cathode) assembly. Through this, a laminate having a [first layer (carbon layer) / second layer (platinum layer)](anode) / membrane / electrode (cathode) structure is obtained.

[0127] Example 3 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0128]

[0129] Example 4

[0130] FIG. 5 is a diagram briefly illustrating the membrane-electrode assembly of Example 4 and the reaction in a fuel cell containing the same.

[0131]

[0132] Fabrication of electrode (anode) and fabrication of membrane-electrode assembly

[0133] Carbon black is obtained by wet grinding carbon black dispersed in a solvent as a carbon-based material and then drying it. A carbon black dispersion in which an ion conductor and a solvent are mixed with the carbon black is coated onto a release film and then dried in an oven. The material dried on the release film can be the first layer (carbon layer).

[0134] The above first layer (carbon layer) is transferred onto the film of a separately prepared membrane-electrode (cathode) assembly. Through this, a laminate having a first layer (carbon layer) / membrane / electrode (cathode) structure is obtained.

[0135] Independently, a platinum solution is prepared. In the total amount of 100% by weight of the platinum solution, the platinum content may be 10 to 40% by weight (stock solution) or 1 to 10% by weight (diluted solution).

[0136] The above platinum solution is coated onto the first layer of the laminate having the first layer (carbon layer) / membrane / electrode (cathode) structure and then dried. Through this, a laminate having the [second layer (platinum layer) / first layer (carbon layer)](anode) / membrane / electrode (cathode) structure is obtained.

[0137] Example 4 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0138]

[0139] Example 5

[0140] FIG. 6 is a diagram briefly illustrating the membrane-electrode assembly of Example 5 and the reaction within a fuel cell containing the same.

[0141]

[0142] By combining the cathode of Example 2 and the anode of Example 3, a laminate with a structure of [first layer (carbon layer) / second layer (platinum layer)](anode) / film / [first layer (carbon layer) / second layer (platinum layer)](cathode) is manufactured.

[0143] Example 5 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0144]

[0145] Example 6

[0146] FIG. 7 is a diagram briefly illustrating the membrane-electrode assembly of Example 6 and the reaction in a fuel cell containing the same.

[0147]

[0148] By combining the cathode of Example 2 and the anode of Example 4, a laminate with a structure of [second layer (platinum layer) / first layer (carbon layer)](anode) / film / [first layer (carbon layer) / second layer (platinum layer)](cathode) is manufactured.

[0149] Example 5 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0150]

[0151] Example 7

[0152] FIG. 8 is a diagram briefly illustrating the membrane-electrode assembly of Example 7 and the reaction in a fuel cell containing the same.

[0153]

[0154] By combining the cathode of Example 1 and the anode of Example 3, a laminate with a structure of [first layer (carbon layer) / second layer (platinum layer)](anode) / film / [second layer (platinum layer) / first layer (carbon layer)](cathode) is manufactured.

[0155] Example 5 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0156]

[0157] Example 8

[0158] FIG. 9 is a diagram briefly illustrating the membrane-electrode assembly of Example 8 and the reaction in a fuel cell containing the same.

[0159]

[0160] By combining the cathode of Example 1 and the anode of Example 4, a laminate with a structure of [second layer (platinum layer) / first layer (carbon layer)](anode) / film / [second layer (platinum layer) / first layer (carbon layer)](cathode) is manufactured.

[0161] Example 5 takes at least 1 day to manufacture the final membrane-electrode assembly.

[0162]

[0163] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

1. An electrode having a multilayer structure including a laminate of a first layer and a second layer, The first layer above comprises a carbon-based material, and The above second layer comprises an active metal, Electrode for fuel cell.

2. In Paragraph 1, The above first layer does not contain an active metal, and The above second layer does not contain carbon-based materials, Electrode for fuel cell.

3. In Paragraph 1, The above carbon-based material has a BET specific surface area of ​​0 m 2 / g exceeding 2000 m 2 / g or less, Electrode for fuel cell.

4. In Paragraph 1, The above carbon-based material may include carbon black, graphite, carbon nanofibers, graphitized carbon nanofibers, carbon nanotubes, carbon nanohorns, carbon nanowires, or combinations thereof. Carbon black includes, for example, Denka black, Ketjen black, acetylene black, channel black, furnace black, lamp black, thermal black, or combinations thereof. Electrode for fuel cell.

5. In Paragraph 1, The above active metal is Precious metals including platinum, palladium, iridium, ruthenium, and silver; Non-precious metals including nickel, cobalt, and iron; or including a combination of these, Electrode for fuel cell.

6. In Paragraph 1, The first layer and the second layer each independently further comprise an ion conductor, Electrode for fuel cell.

7. In Paragraph 6, The above ion conductor is an ionomer or polymer having ion conductivity, Electrode for fuel cell.

8. In Paragraph 1, The loading amount of the first layer per area of ​​the electrode is 0.05 mg / cm² 2 Exceeding 5 mg / cm² 2 Lee Ha-in, Electrode for fuel cell.

9. In Paragraph 1, The loading amount of the second layer per area of ​​the electrode is 0.05 mg / cm² 2 Exceeding 5 mg / cm² 2 Lee Ha-in, Electrode for fuel cell.

10. A cathode electrode and an anode electrode positioned opposite each other; and It includes a polymer electrolyte membrane located between the cathode electrode and the anode electrode, and At least one of the above cathode electrode and the above anode electrode is an electrode of any one of claims 1 to 9. Membrane-electrode assembly for a fuel cell.

11. In Paragraph 10, The above first layer comes into contact with the polymer electrolyte membrane, The above second layer is in contact with the polymer electrolyte membrane, Membrane-electrode assembly for a fuel cell.

12. A fuel cell comprising a membrane-electrode assembly according to paragraph 11.

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