KR20220099785A - Electrochemically Active Composite Material for Polymer Electrolyte Membrane Fuel Cell - Google Patents

Abstract

The present invention relates to a polymer electrolyte fuel cell, and specifically, to an electrode composite for a polymer electrolyte fuel cell capable of improving the activity of an electrode by maximizing the formation of a three-phase interface formed by a catalyst/a binder/a fuel in an electrode catalyst layer of the polymer electrolyte fuel cell, a manufacturing method thereof, an electrode including the same, and a fuel cell including the electrode.

Description

Electrochemically Active Composite Material for Polymer Electrolyte Membrane Fuel Cell

The present invention relates to a polymer electrolyte fuel cell, and an electrode composite for a polymer electrolyte fuel cell capable of improving the activity of an electrode by maximizing the formation of a three-phase interface between a catalyst/binder/fuel in an electrode catalyst layer of a polymer electrolyte fuel cell, and manufacturing the same It relates to a method, an electrode including the same, and a fuel cell including the electrode.

Globally, fossil energy is likely to be depleted within a few years. In addition, interest in alternative energy sources is rising due to the continuous rise in oil prices and environmental pollution caused by the use of fossil energy. Among alternative energy sources, research on environmentally friendly hydrogen energy, which can be supplied abundantly and indefinitely on Earth, is being rapidly progressed in recent years, and "fuel cell" is at the center of it.

A fuel cell is a device that directly converts chemical energy into electrical energy. The basic structure of a fuel cell is composed of an anode supporting a catalyst, an oxygen electrode, and a membrane/electrode assembly manufactured by putting an electrolyte membrane between the two electrodes.

In a fuel cell, the performance of the membrane/electrode assembly is greatly influenced by each electrode, and the electrode activity greatly differs depending on the three-phase interface formed by the catalyst/binder/fuel. Therefore, these three-phase interface control techniques in the electrode catalyst layer are considered as factors that are intuitive to the cell performance.

Although the existing electrode binder is the same material as the hydrogen ion conductive polymer electrolyte membrane and applied to the electrode binder solution, the membrane/electrode interface stability is greatly improved, but problems such as aggregation between the polymer dissolved in a polar solvent and the catalyst are reduced in performance appeared to be the biggest cause of Therefore, in order to solve this problem, it is required to develop a technology for improving electrode activity by maximizing the formation of a three-phase interface between catalyst/binder/fuel.

Republic of Korea Patent No. 10-2008-0048352

As a result of numerous studies, the present inventors have completed the present invention by developing a technology capable of improving electrode activity by drying at a low temperature when forming an electrode composite in a polymer electrolyte fuel cell.

Accordingly, an object of the present invention is to maximize the formation of a three-phase interface between catalyst/binder/fuel by drying at a low temperature of 0° C. or less when forming the electrode composite, thereby improving electrode activity for a polymer electrolyte fuel cell electrode composite, a manufacturing method thereof, An electrode including the same and a fuel cell including the electrode are provided.

The object of the present invention is not limited to the above-mentioned object, and even if not explicitly mentioned, the object of the invention that can be recognized by a person of ordinary skill in the art from the description of the detailed description of the invention to be described later may also be included. .

In order to achieve the object of the present invention described above, the present invention first comprises the steps of preparing an electrode composite solution for a polymer electrolyte fuel cell; and drying the electrode composite solution at less than 0°C.

In a preferred embodiment, the electrode composite solution includes a catalyst, a polymer binder and a solvent.

In a preferred embodiment, the catalyst is platinum (Pt), platinum/iridium (Pt/Ir), rhodium (Rh), platinum/rhodium (Pt/Rh), platinum/ruthenium (Pt/Ru), palladium (Pd) It is one or more selected from among.

In a preferred embodiment, the polymer binder is Nafion, Flemion, Aciplex, perfluorosulfonic acid (PFSA), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVdF), polytrifluoro It is at least one selected from the group consisting of lochloroethylene (PCTFE), polyvinylidene fluoride-hexafluoropropylene (PVdF-HEP).

In a preferred embodiment, the polymer binder is a polyimide-based polymer, a polyetherimide-based polymer, a polyphenylene sulfide-based polymer, a polysulfone-based polymer, a polyethersulfone-based polymer, a polyetherketone-based polymer, and a polyetheretherketone polymer. , polyphenylquinoxaline-based, polyphenyline oxide, polyphenylline sulfide polymer is introduced into any one or more selected from the group consisting of sulfonic acid.

In a preferred embodiment, the solvent is methanol, ethanol, isopropyl alcohol (IPA), distilled water (Deionized-Water), N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethyl It is at least one selected from the group consisting of acetamide (DMAc) and dimethyl sulfoxide (DMSO).

In addition, the present invention provides an electrode composite for a polymer electrolyte fuel cell manufactured by any one of the manufacturing methods described above.

In a preferred embodiment, particles and pores having a diameter of 100 nanometers or less are formed.

In addition, the present invention is any one support selected from the group consisting of carbon fiber, felt or carbon paper; and the above-described electrode composite supported on the support.

In addition, the present invention provides a fuel cell including the above-described electrode for a fuel cell.

According to the present invention described above, it is possible to obtain the effect of increasing the active surface area of the electrode by having nanometer-sized pores and particles in the process of aggregation of the electrode composite through low-temperature drying at 0° C. or less, and, through this, catalyst / By maximizing the formation of the three-phase interface formed by the binder/fuel, the electrode activity can be improved.

These technical effects of the present invention are not limited only to the range mentioned above, and even if not explicitly mentioned, the effect of the invention that can be recognized by those of ordinary skill in the art from the description of the specific content for the implementation of the invention to be described later is also of course included

1 is a photograph showing the morphology of an electrode composite according to an embodiment of the present invention, and FIG. 2 is a photograph showing the morphology of a comparative electrode composite as a control.
3 is a performance comparison graph of a fuel cell to which the electrode including the electrode composite shown in FIG. 1 and the electrode including the comparative electrode composite shown in FIG. 2 are applied.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the description of the invention is present, but one or more other It should be understood that it does not preclude the possibility of addition or presence of features or numbers, steps, operations, components, parts, or combinations thereof.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present invention. does not

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description. In particular, when the terms "about", "substantially", etc. of degree are used, they may be construed as being used in a sense at or close to the numerical value when manufacturing and material tolerances inherent in the stated meaning are presented. .

In the case of a description of a temporal relationship, for example, if the temporal relationship is described as 'after', 'following', 'after', 'before', etc., 'immediately' or 'directly' This includes cases that are not continuous unless ' is used.

Hereinafter, the technical configuration of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Like reference numbers used to describe the invention throughout the specification refer to like elements.

The technical feature of the present invention is to increase the active surface area of the electrode by having nanometer-sized pores and particles in the process of aggregation of the electrode composite through low-temperature drying at 0° C. or less, resulting in the formation of a three-phase interface between catalyst/binder/fuel There is a method for manufacturing an electrode composite that can maximize

Accordingly, the method for producing an electrode composite for a polymer electrolyte fuel cell of the present invention includes the steps of preparing an electrode composite solution for a polymer electrolyte fuel cell; and drying the electrode composite solution at 0° C. or less.

Here, the electrode composite solution includes a catalyst, a polymer binder, and a solvent, and after adding the catalyst and the polymer binder to the solvent, it can be uniformly dispersed by ultrasonication. In particular, it may be preferable to add the polymer binder to the electrode composite solution in a solution state.

As the catalyst as an electrode redox catalyst, any known material may be used as long as it has excellent oxidation and oxygen reduction properties such as hydrogen, methanol, ethanol, formic acid, etc., but in one embodiment, Pt, Ru, W, Mo, P, Si, Co, Cs, V, and may be selected from a mixture or alloy of two or more selected from the group, such as, platinum (Pt), platinum / iridium (Pt / Ir), rhodium (Rh), platinum It may be at least one selected from /rhodium (Pt/Rh), platinum/ruthenium (Pt/Ru), and palladium (Pd).

The polymer binder is not limited as long as it is a material having excellent hydrogen ion conductivity, but may be a fluorine-based binder, a sulfonated hydrocarbon-based binder, or a combination thereof.

In one embodiment, the fluorine-based binder is perfluorosulfonic acid (PFSA), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVdF), polytrifluorochloroethylene (PCTFE), polyvinylidene fluoride Ride- may be any one or more selected from the group consisting of hexafluoropropylene (PVdF-HEP). In particular, perfluorinated polymers such as Nafion, Flemion, Aciplex, etc. introduce a sulfonic acid group at the terminal group of the side chain to form a cluster. It is a structure that is easy to do.

A sulfonated hydrocarbon-based binder is a hydrocarbon-based polymer that is sulfonated. In the case of a hydrocarbon-based polymer, the polymer itself is sulfonated in concentrated sulfuric acid or fuming sulfuric acid (post-sulfonation) or fuming After introducing a sulfonic acid group to a monomer in sulfuric acid, a sulfonated polymer can be prepared by a condensation reaction (monomer sulfonation, monomer-sulfonation). Sulfonation in the present invention includes both postsulfonation and monomer sulfonation. . Here, the number average molecular weight of the hydrocarbon-based polymer is 1,000 to 1,000,000, preferably, 5,000 to 500,000 is preferably used. If the number average molecular weight of the polymer is less than 1,000, the stability of the polymer may decrease, and when it exceeds 1,000,000 This is because a problem of decreasing solubility may occur. The sulfonated hydrocarbon-based binder is one embodiment of a polyimide-based polymer, a polyetherimide-based polymer, a polyphenylene sulfide-based polymer, a polysulfone-based polymer, a polyethersulfone-based polymer, a polyetherketone-based polymer, and a polyetheretherketone. A sulfonic acid may be introduced into any one or more selected from the group consisting of polymers, polyphenylquinoxaline-based polymers, polyphenylline oxides, and polyphenylline sulfide polymers.

The solvent is not limited as long as the degree of dispersion of the polymer is excellent, but methanol, ethanol, isopropyl alcohol (IPA), distilled water (Deionized-Water), N-methylpyrrolidone (NMP), dimethylform It may be at least one selected from the group consisting of amide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO).

Next, the electrode composite for a polymer electrolyte fuel cell of the present invention is prepared by the above-described method to form particles and pores having a diameter of 100 nanometers or less.

Therefore, the electrode composite for a fuel cell in which the electrode composite of the present invention is supported on any one support selected from the group consisting of carbon fiber, felt, or carbon paper has nano-sized porosity on the electrode surface, so that the surface area is widened, so that mass transfer of fuel is difficult. can be advantageous

Example 1

1. Preparing the electrode complex solution

Platinum catalyst 0.1g, distilled water 0.1g, Nafion solution 0.1505g, and isopropyl alcohol 0.1g were put in a 20cc mixing container and dispersed in a sonicator for about 1 hour to prepare an electrode composite solution. (Nafion solution is isopropyl alcohol Can I say that I used alcohol? ==> Yes, I can.)

2. Drying step

The prepared electrode composite solution was freeze-dried in a freeze dryer at a pressure of 10 mmtorr and a temperature of ??65° C. for 24 hours to obtain an electrode composite.

Comparative Example 1

The electrode composite solution prepared in Example 1 was dried in a dryer at a temperature of 80° C. for 24 hours to obtain an electrode composite of Comparative Example.

Experimental Example 1

The electrode composite obtained in Example 1 and the electrode composite obtained in Comparative Example 1 were enlarged by SEM to observe the morphologies, and the results are shown in FIGS. 1 and 2, respectively.

1 and 2, as in the present invention, the electrode composite obtained by drying the electrode composite solution at a low temperature of less than 0 ° C. has a particle size and a pore size of 100 nm compared to a comparative example electrode composite having micro-sized particles. It can be confirmed that it is an agglomerate composed of the following particles. Therefore, it can be easily expected that the surface area becomes wider than that of the micro-sized particulate agglomerate of FIG. 2 .

Example 2

The electrode composite prepared in Example 1 was repeatedly subjected to ultrasonication and stirring for 24 hours to maintain a uniform dispersion state, and then applied to carbon fibers at a loading amount of 0.1 mg Pt/cm 2 to obtain an electrode for a fuel cell.

Comparative Example 2

An electrode for a comparative fuel cell was obtained in the same manner as in Example 2, except that the comparative electrode composite prepared in Comparative Example 1 was used.

Experimental Example 2

The initial performance evaluation of the unit cell was performed using the MEA including the fuel cell electrode obtained in Example 2 and the comparative fuel cell electrode obtained in Comparative Example 2, and the results are shown in FIG. 2 .

From FIG. 2, it can be seen that the fuel cell including the electrode composite of the present invention has finer pores formed on the electrode surface and the surface area is widened compared to the case where the electrode composite of the comparative example is included, so that the fuel delivery is advantageous, so that the performance is improved. Able to know.

Although the present invention has been illustrated and described by way of preferred embodiments as described above, it is not limited to the above-described embodiments, and those of ordinary skill in the art to which the present invention pertains within the scope not departing from the spirit of the present invention Various changes and modifications will be possible.

Claims (10)

preparing an electrode composite solution for a polymer electrolyte fuel cell; and
A method for producing an electrode composite for a polymer electrolyte fuel cell comprising; drying the electrode composite solution at less than 0°C.
The method of claim 1,
The electrode composite solution is a method for producing an electrode composite for a polymer electrolyte fuel cell, characterized in that it contains a catalyst, a polymer binder and a solvent.
3. The method of claim 2,
The catalyst is at least one selected from platinum (Pt), platinum/iridium (Pt/Ir), rhodium (Rh), platinum/rhodium (Pt/Rh), platinum/ruthenium (Pt/Ru), and palladium (Pd). A method for manufacturing an electrode composite for a polymer electrolyte fuel cell, characterized in that
3. The method of claim 2,
The polymer binder is Nafion, Flemion, Aciplex, perfluorosulfonic acid (PFSA), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVdF), polytrifluorochloroethylene (PCTFE) , polyvinylidene fluoride-hexafluoropropylene (PVdF-HEP), characterized in that any one or more selected from the group consisting of a polymer electrolyte fuel cell electrode composite manufacturing method.
3. The method of claim 2,
The polymer binder is a polyimide-based polymer, a polyetherimide-based polymer, a polyphenylene sulfide-based polymer, a polysulfone-based polymer, a polyethersulfone-based polymer, a polyetherketone-based polymer, a polyetheretherketone polymer, and a polyphenylquinoxaline-based polymer. A method for producing an electrode composite for a polymer electrolyte fuel cell, characterized in that sulfonic acid is introduced into at least one selected from the group consisting of , polyphenyline oxide, and polyphenyline sulfide polymers.
3. The method of claim 2,
The solvent is methanol, ethanol, isopropyl alcohol (IPA), distilled water (Deionized-Water), N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), A method for manufacturing an electrode composite for a polymer electrolyte fuel cell, characterized in that at least one selected from the group consisting of dimethyl sulfoxide (DMSO).
An electrode composite for a polymer electrolyte fuel cell manufactured by the method of any one of claims 1 to 6.
8. The method of claim 7,
An electrode composite for a polymer electrolyte fuel cell, characterized in that particles and pores having a diameter of 100 nanometers or less are formed.
any one support selected from the group consisting of carbon fiber, felt, or carbon paper; and
A fuel cell electrode comprising; the electrode composite of claim 7 supported on the support.
A fuel cell comprising the electrode for a fuel cell of claim 9 .

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