KR100880092B1 - Surface modification of hydrocarbon-based polymer electrolyte membrane - Google Patents

Abstract

The present invention is a polymer comprising a portion capable of swelling in a micro-domain size by a Cl solvent without dissolution in a Cl solvent, and is limited to the swellable portion, and a chemical reaction proceeds and is modified. It is characterized in that the polymer; And it provides a preparation method thereof.

In addition, the present invention is an electrolyte membrane characterized in that the surface fluorinated modified only in the hydrophobic block containing no sulfonic acid group in the sulfonated hydrocarbon-based segmented block copolymer polymer membrane; Its preparation method; A fuel cell including the membrane-electrode assembly (MEA) having the electrolyte membrane and the membrane-electrode assembly is provided.

The membrane-electrode assembly (MEA) having the electrolyte membrane according to the present invention has excellent adhesion to the membrane-electrode, thereby reducing the interface resistance between the electrolyte membrane and the electrode when applied to a fuel cell, thereby improving the performance of the fuel cell as well as driving the membrane. Since the separation of the electrolyte membrane-electrode assembly does not occur, the performance of the fuel cell can be maintained and can be driven for a long time and stable.

Fluorinated reforming, MEA, membrane-electrode assembly, electrolyte membrane, fuel cell

Description

Surface Modification of Hydrocarbon-Based Polymer Electrolyte Membrane {SURFACE MODIFICATION OF HYDROCARBON-BASED POLYMER ELECTROLYTE MEMBRANE}

1 is a schematic diagram of a two-dimensional pattern of an electrolyte membrane surface-fluorinated modified according to the present invention.

Figure 2 is a film (s -PEEK) prepared according to one embodiment of the present invention-electrode assembly (MEA-a1, a2-MEA, MEA-a3) and the films (SG- s -PEEK1, SG- s -PEEK2 ) It is a photograph after immersing electrode assembly ( MEA-b1 , MEA-b2 ) in water for 100 hours or more.

3 is a result showing the performance of the hydrogen ion exchange membrane fuel cell (PEMFC) to which the membrane-electrode assembly prepared according to one embodiment of the present invention is applied.

4 is a long-term durability evaluation results showing the voltage change in the constant current mode (@ 0.6 V / cm ² ) of the hydrogen ion exchange membrane fuel cell (PEMFC) to which the membrane-electrode assembly prepared according to an embodiment of the present invention is applied.

5 is a result showing the performance of the direct methanol fuel cell (DMFC) to which the membrane-electrode assembly prepared according to one embodiment of the present invention is applied.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte membrane that can be used in a fuel cell, and more particularly, to surface fluorination only in a fraction containing no hydrophobic blocks such as sulfonic acid groups in a sulfonated hydrocarbon-based segmented block copolymer polymer membrane. The present invention relates to an electrolyte membrane characterized by being modified.

A fuel cell is a power generation system that converts chemical energy produced by electrochemical reaction between fuel (hydrogen or methanol) and oxidant (oxygen) into electrical energy. It is a next-generation energy source with eco-friendly features with high energy efficiency and low pollutant emission. Is being developed. The fuel cell can be used by selecting a fuel cell for high temperature and low temperature according to the application field, and is generally classified according to the type of electrolyte. For high temperature, a solid oxide fuel cell (SOFC) and molten carbonate are used. Fuel cell (Molten Carbonate Fuel Cell, MCFC) and the like, Alkaline Fuel Cell (AFC) and Polymer Electrolyte Membrane Fuel Cell (PEMFC) are being developed for low temperature.

Subdivided into a polymer electrolyte fuel cell, the direct methanol fuel used by supplying a hydrogen ion exchange membrane fuel cell (PEMFC) that uses hydrogen gas as fuel and liquid methanol directly to the anode as a fuel Batteries (Direct Methanol Fuel Cell, DMFC). Polymer electrolyte fuel cells have been spotlighted as portable, automotive, and home power supplies for their low operating temperatures of less than 100 ° C., elimination of leaks due to the use of solid electrolytes, fast start-up and response characteristics, and excellent durability. In particular, research into a portable fuel cell has been continuously conducted since it can be miniaturized as a high output fuel cell having a larger current density than other fuel cells.

The unit cell structure of the fuel cell has a structure in which an anode (anode, fuel electrode) and a cathode (cathode, oxygen electrode) are coated on both sides of an electrolyte membrane made of a polymer material, which is a membrane-electrode assembly (Membrane Electrode). Assembly, MEA). The membrane-electrode assembly (MEA) is an electrochemical reaction between hydrogen and oxygen, and is composed of a cathode, an anode, and an electrolyte membrane, that is, an ion conductive electrolyte membrane (eg, a hydrogen ion conductive electrolyte membrane). In the anode, hydrogen or methanol, which is a fuel, is supplied to generate an oxidation reaction of hydrogen to generate hydrogen ions (H ⁺ ) and electrons. In the cathode, hydrogen ions and oxygen that have passed through the polymer electrolyte membrane are combined to form a reduction reaction of oxygen. Water is produced. The membrane-electrode assembly has a form in which the electrode catalyst layers of the anode and the cathode are coated on both sides of the ion conductive electrolyte membrane, and the material forming the electrode catalyst layer is Pt (platinum), Pt-Ru (platinum-ruthenium), or the like. The catalyst substance of is supported on a carbon carrier. Membrane-electrode assembly (MEA), which can be seen as a key component of the electrochemical reaction of fuel cells, is especially used for ion-conducting electrolyte membranes and platinum catalysts, which have a high price ratio, and is directly related to power production efficiency. It is considered as the most important part in improving the performance and increasing the price competitiveness.

Conventional methods for making MEAs that are commonly used include preparing a paste by mixing a catalytic material with a hydrogen ion conductive binder, ie, a fluorine-based Nafion Ionomer, and water and / or an alcohol solvent. It is coated with a carbon cloth or carbon paper, which serves as an electrode support that supports the catalyst layer and at the same time serves as a gas diffusion layer, and then dried and thermally fused and transferred to a hydrogen ion conductive electrolyte membrane.

Redox reaction of hydrogen and oxygen by the catalyst in the catalyst layer; Transfer of electrons by tightly bonded carbon particles; Securing passages for supplying hydrogen, oxygen and moisture and for discharging excess gas after the reaction; The movement of oxidized hydrogen ions must be carried out at the same time. Furthermore, in order to improve performance, the area of the triple phase boundary where the feed fuel, the catalyst and the ion conductive polymer electrolyte membrane meet must be increased to reduce the activation polarization, and the interface between the catalyst layer and the electrolyte membrane and the catalyst layer The interface between the gas diffusion layer and the gas diffusion layer must be uniformly bonded to reduce ohmic polarization at the interface.

Therefore, in order to improve the performance of the fuel cell by reducing the interface resistance between the catalyst layer and the electrolyte membrane as much as possible, not only the bonding force between the catalyst layer and the electrolyte membrane should be provided during MEA production, but also the interface bonding between the catalyst layer and the electrolyte membrane continues during fuel cell operation. It must be maintained.

In general, in the case of using a Nafion electrolyte membrane as a fuel cell electrolyte membrane, a liquid phase such as a Nafion Ionomer solution is used to improve the interfacial adhesion between the catalyst layer and the Nafion electrolyte membrane and to increase the efficiency of the catalyst layer. The electrolyte is impregnated into the catalyst layer. In the actual reaction, the migration rate of hydrogen ions to the platinum (Pt) catalyst is much faster through the ionomer than to the water. In the method of impregnating the ionomer into the catalyst layer, a method of preparing a catalyst slurry by adding a Nafion ionomer solution together and applying it on a carbon cloth or carbon paper as an electrode support to form a catalyst layer, and then coating the Nafion ionomer solution thinly thereon Use Here, the components of the coating layer and the electrolyte membrane on the catalyst layer are all the same as Nafion, so that the adhesion between the membrane and the catalyst layer is improved because of excellent miscibility. Therefore, in order to improve the adhesion between the electrolyte membrane and the catalyst layer and further improve the performance of the fuel cell by reducing the interface resistance between the membrane and the electrode, it is important to use the same or similar coating layer components as those of the electrolyte membrane. .

In general, an electrolyte membrane used in a polymer electrolyte fuel cell may be divided into a fluorine polymer electrolyte and a hydrocarbon polymer electrolyte. Nafion, a product of Du Pont Co., Ltd., is a representative example of a fluorine-based polymer electrolyte membrane, and is currently being most commercialized due to its excellent ion conductivity, chemical stability, and ion selectivity. However, the fluorinated polymer electrolyte membrane has a low price due to its high performance, but has low industrial utility due to its high price, high methanol crossover through methanol, and reduced efficiency of the polymer membrane at 80 ° C. or higher. Therefore, research is being actively conducted on hydrocarbon-based polymer electrolyte membranes which can compete in terms of price. In particular, polyetherketone, polyethersulfone-based polyarylene ether (Poly (etherylene ethers)) polymers are being studied in fuel cells due to their excellent chemical stability and mechanical properties.

However, when the non-fluorine-based, or hydrocarbon-based polymer membrane is used as the electrolyte membrane of the fuel cell and the Nafion ionomer is coated on the catalyst layer to fabricate the MEA, the adhesion between the electrolyte membrane and the catalyst layer is reduced during the fuel cell operation. There was a disadvantage that the performance is reduced due to the increase. This is because the physical and chemical properties of the Nafion ionomer used as the coating liquid of the hydrocarbon-based polymer membrane and the catalyst layer are different, resulting in poor adhesion.

However, until now, no effective method for improving the bonding strength between the hydrocarbon-based polymer electrolyte membrane and the electrode in the polymer electrolyte fuel cell has not been proposed.

Gubler et. Of Switzerland. al in his paper [ Fuel Cells , 2004 , 4 (3), 196] discloses a method for improving the adhesion between an electrolyte membrane and an electrode by using radiation-grafted FEP-g-polystyrene as an electrolyte membrane. However, using an FEP 100A [25 μm-thick poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP)] film, which is a commercially available fluorinated thin film instead of a hydrocarbon-based film, as an electrolyte membrane, the physical properties of the FEP film are improved. The styrene monomer was grafted onto the FEP film by radiation to give the hydrogen ion conductivity, and then hydrogen sulfide conductivity was given to the Grafted FEP film using a sulfonating agent. In order to improve the adhesion between the membrane and the electrode, the sulfonated Grafted FEP electrolyte membrane was immersed in the same Nafion ionomer dispersion as the catalyst layer binder, dried, coated with Nafion, and then swelled again with water. After doing so, there are disadvantages such as a cumbersome manufacturing process such as manufacturing MEA through thermocompression bonding with the electrode and a long process time.

EP 0 572 810 Al discloses RAI Research Corp. Disclosed is a method for preparing a radiation-grafted cationic electrolyte membrane by irradiating plasma generated from oxidizing gases such as oxygen, ozone, chlorine oxide and fluorine oxide to the benzene sulfonic acid electrolyte membrane of R1010 or R1020 provided by . In this patent, MEA was prepared by using Nafion ionomer-containing electrodes in a radiation-grafted cationic electrolyte membrane to improve the adhesion between the electrolyte membrane and the catalyst layer, thereby reducing the contact interface resistance of the electrolyte membrane-electrode. However, in order to manufacture a radiation-grafted electrolyte membrane by plasma etching used in the conventional research, disadvantages such as cumbersome manufacturing process such as generating plasma from oxidizing gas and enormous economic cost There is this.

The present inventors studied fluorination treatment of sulfonated hydrocarbon-based polymer electrolyte membrane in Cl solvent in order to increase the bonding force between the electrolyte membrane and the electrode and reduce the interfacial resistance. It has been found that only segments containing no sulfonic acid groups, i.e., minor blocks, are swelled by Cl-based solvents and surface fluorinated modified in the segmented blockcopolymer electrolyte membrane. The present invention is based on the above invention.

The present invention is a polymer comprising a portion capable of swelling in a micro-domain size by a Cl solvent without dissolution in a Cl solvent, and is limited to the swellable portion, and a chemical reaction proceeds and is modified. It provides a polymer characterized by.

In addition, the present invention provides a first method of immersing a polymer comprising a portion capable of swelling to a micro-domain size by a Cl solvent in a Cl solvent containing a chemical reagent without being dissolved in a Cl solvent. Including a step, the chemical reaction proceeds only to the swellable portion provides a method for producing a modified polymer.

In addition, the present invention is an electrolyte membrane characterized in that the surface of the sulfonated hydrocarbon-based segmented block copolymer polymer (Segmented Block Copolymer) is selectively selectively fluorinated only in the minor block containing no sulfonic acid group; A membrane-electrode assembly (MEA) having the electrolyte membrane; And it provides a fuel cell comprising the membrane-electrode assembly.

Furthermore, the present invention includes a first step of immersing a sulfonated hydrocarbon-based segmented blockcopolymer membrane in a Cl-based solution containing a fluorinating agent to selectively surface fluorinated modified only to a few blocks containing no sulfonic acid group. A method for producing a sulfonated hydrocarbon-based polymer membrane is provided.

Hereinafter, the present invention will be described in detail.

Part of the polymer which is not soluble in a specific solvent is partially swelled by the specific solvent, for example, a segment exhibiting hydrophobicity, that is, a hydrophobic block is different in size depending on molecular weight, but is about the size of a micro unit, In the present invention, this is referred to as 'micro-domain size'.

An example of a polymer that does not dissolve in a specific solvent is a segmented block copolymer, and the segmented block copolymer includes a portion which does not swell in a solvent and a portion that swells in a solvent.

In the present invention, the sulfonated hydrocarbon-based segmented block copolymer (Segmented Block Copolymer) is a part that exhibits hydrophilicity due to the sulfonated group, that is, a part that exhibits hydrophobicity due to the absence of the hydrophilic block and the sulfonated group, that is, the hydrophobic block is a chemical bond Contains block polymers.

In the present invention, the swelling of the polymer in the solvent means that the covalent bond in the polymer is maintained while the solvent penetrates into the polymer. On the other hand, in the present invention that the polymer is dissolved in the solvent means that the covalent bond in the polymer is lost.

If the basic block of the polymer and the solvent have the same or similar properties, the polymer swells due to the penetration of the solvent. If the solvent continues to penetrate, the polymer may be dissolved in the solvent.

If both polymer and solvent have the same binding force, they dissolve each other. For example, the polarity melts well with the polarity and the nonpolarity. Solubility parameter (δ) was applied to the polymer to make a kind of data. When the solubility constants are about the same, they dissolve together. For example, dissolution occurs if | δ ₁ -δ ₂ | <1 (cal / cm ³ ) ^1/2 . When the solubility constants of the polymer and the solvent become similar, the polymer without crosslinking dissolves unconditionally. However, the crosslinked polymer only swells. In other words, not only the solubility index but also the degree of crosslinking is a large parameter that determines whether the solvent can penetrate.

In the present invention, the polymer to be modified in the Cl solvent is a part having no affinity for the Cl solvent (eg, a part having a sulfonic acid group), that is, the hydrophilic block is not dissolved and swelled in the Cl solvent, and is not a Cl solvent. The part having affinity (for example, a part without a sulfonic acid group), that is, a hydrophobic block is characterized in that it is swollen in a Cl solvent. The present invention considers the relationship between the solubility index of the Cl-based solvent and the solubility index of the polymer, and / or the crosslinking degree of the polymer, and selects the appropriate unit (s) and adjusts the distribution of the position and number thereof. The part which is not dissolved in the solvent but has an affinity for the Cl solvent can design a segmented block copolymer that is swollen in the Cl solvent.

Therefore, unlike the prior art of randomly fluorinating a polymer by using a plasma or the like, the present invention controls the position, number, density, distribution, etc. of a functional group having no affinity for a Cl-based solvent, such as a sulfonated group in a polymer, As a result of this, by controlling the position, number, and distribution of the swellable portion in the polymer, the chemical reaction may be limited to the swellable portion, that is, the minor block, to selectively adjust the polymer modification such as fluorination.

In addition, the plasma treatment involves a condition in which the fluorine-containing compound must be in a gaseous state in order to graf the fluorine-containing compound to the polymer, but in the present invention, a portion containing the solution containing the fluorine-containing compound and swelled in the solution Since the chemical reaction occurs in the fluorine-containing compound does not have the above restrictions.

A hydrophilic block having a functional group having no affinity for a Cl solvent such as a sulfonic acid group may be distributed as a block in the polymer.

In the present invention, the portion that is not swellable by the Cl solvent may preferably include at least one hydrophilic functional group selected from the group consisting of sulfonic acid groups, phosphoric acid groups, and carboxylic acid groups.

Non-limiting examples of Cl solvents include chloroform (CHCl ₃ ), dichloromethane (CH ₂ Cl ₂ ), chloromethane (CH ₃ Cl), carbon tetrachloride (CCl ₄ ), 1-chlorobutane, 1-chloropentane, 1-chloropropane, 2-chloropropane, chlorobenzene and 1,2-dichloroethane.

According to the present invention, the polymer may be modified to include a swellable portion by Cl solvent and limited to the swellable portion.

Hereinafter, the present invention will be described in more detail with a focus on the surface of the sulfonated hydrocarbon-based segmented block copolymer polymer electrolyte membrane, which does not contain sulfonic acid groups (fractional blocks).

In the present invention, the surface fluorinated modified means that the polymer side chain is fluorinated, not the backbone of the polymer backbone.

The hydrophobic block which does not contain the sulfonic acid group is a swellable portion of the Cl solvent and is a portion capable of surface fluorination by chemical reaction with a fluorinating agent in the solution. The sulfonated hydrocarbon polymer electrolyte membrane is not dissolved in a Cl solvent.

Solubility index difference can be mainly used in order to prevent the fractional block portion containing no sulfonic acid group from swelling in the Cl solvent but not dissolving.

The surface fluorination modification may be a grafting bond of a fluorine substituted or fluorine containing compound.

The sulfonated hydrocarbon-based segmented block copolymer electrolyte membrane that is the surface fluorinated reforming target may be a non-fluorinated sulfonated hydrocarbon-based polymer electrolyte membrane or a partially fluorinated sulfonated hydrocarbon-based polymer electrolyte membrane.

According to the present invention, the non-fluorinated sulfonated hydrocarbon-based segmented blockcopolymer electrolyte membrane to be subjected to surface fluorination is sulfonated poly (arylene ether) s, sulfonated polyimide-based sulfonated polyimide. block copolymer electrolyte membranes such as (imide) s], sulfonated poly (amide) s, sulfonated polyphosphazenes, sulfonated polystyrenes, etc. ), A multiblock copolymer electrolyte, a graft copolymer electrolyte, and a mixture thereof. In addition, partially fluorinated sulfonated polymer electrolyte membranes may also be subject to surface fluorination modifications, such as sulfonated radiation-grafted FEP-g-polystyrene electrolyte membranes, sulfonated radiation-grafted ETFE-g-polystyrene electrolyte membranes, sulfonated radiation -grafted LDPE-g-polystyrene electrolyte membranes and sulfonated radiation-grafted PVDF-g-polystyrene electrolyte membranes are applicable.

On the other hand, the present invention is a Cl-based solvent containing a chemical reactant to a polymer containing a portion capable of swelling into a micro-domain size by a Cl-based solvent, such as a hydrophobic block, without being dissolved in a Cl-based solvent. Including a first step immersed in, the chemical reaction is limited to the swellable portion to provide a method for producing a modified polymer.

In particular, the method for producing a sulfonated hydrocarbon-based polymer electrolyte membrane surface-fluorinated modified only to a minor block portion containing no sulfonic acid group includes a first step of dipping the sulfonated hydrocarbon-based polymer membrane in a Cl-based solvent containing a fluorinating agent.

The polymer of the present invention may be modified by grafting in the first step.

In particular, the surface fluorination modification of the electrolyte membrane in the present invention can be achieved through the Friedel-Crafts reaction. Friedel-Crafts Alkylation or Friedel-Crafts Acylation reaction is applicable, and Friedel-Crafts Acylation reaction is preferred.

In the present invention, the catalyst applicable in the Friedel-Crafts reaction for fluorination modification of the surface of the electrolyte membrane may be selected from the group of SnCl ₄ , FeCl ₃ , AlCl ₃ , and the like, and AlCl ₃ is preferable.

In the present invention, the solvent used in the Friedel-Crafts reaction for the fluorination of the electrolyte membrane surface may be selected from a solvent group such as CCl ₄ , CHCl ₃ , CH ₂ Cl ₂ , nitrobenzene, Freon or a mixture of the above solvents. Do.

In the present invention, the fluorination agent represented by the following Formula 1 may be used alone or in combination as a fluorination agent in the Friedel-Crafts reaction.

[Formula 1]

,

,

,

, 또는 할로겐 원소이고; X₁은 할로겐 원소, C1~C12의 전불소 혹은 부분 불소계 알킬기, C2~C12의 전불소 혹은 부분 불소계 알케닐기, 혹은

로 표시되고, 이때 R¹ 내지 R⁵ 는 각각 독립적으로 수소, 할로겐 원소, C1~C12의 전불소 혹은 부분 불소계 알킬기, C2~C12의 전불소 혹은 부분 불소계 알케닐기이고; G₁는 수소, 알킬기 혹은 페닐기이며;Where A ¹ is

,

,

,

Or a halogen element; X ₁ is a halogen element, a C1 to C12 all fluorine or partially fluorine alkyl group, C2 to C12 all fluorine or partially fluorine alkenyl group, or

Wherein R ¹ to R ⁵ are each independently hydrogen, a halogen element, a C1 to C12 all fluorine or partial fluorine-based alkyl group, C2 to C12 all fluorine or partially fluorine alkenyl group; G ₁ is hydrogen, an alkyl group or a phenyl group;

, 혹은 이의 조합으로 표시되고; 이때 D₁, D₂ 는 각각 독립적으로 수소, 할로겐 원소, 수산화기,

, 혹은

로 표시되며, m 은 1 내지 6 의 정수이고;Each B is independently -CD ₁ D _2- ,

Or a combination thereof; Where D ₁ , D ₂ Are each independently hydrogen, halogen, hydroxyl,

, or

And m is an integer from 1 to 6;

E is a direct bond, -O-, -S-, -CO-, -SO _2- , -C (CH ₃ ) _2- , or -C (CF ₃ ) _2- , R ⁶ to R ⁹ each independently represents hydrogen, a halogen element, a C1-C12 all-fluorine or partially fluorine-based alkyl group, and C2-C12 all-fluorine or partially fluorine-alkenyl group; n is an integer from 1 to 24;

,

,

,

, 또는 할로겐 원소이고, X₂은 할로겐 원소이고, G₂는 수소, C1~C12 알킬기 혹은 페닐기임.A ² are each independently

,

,

,

Or a halogen element, X ₂ is a halogen element, and G ₂ is hydrogen, a C1-C12 alkyl group or a phenyl group.

At this time, the concentration of the fluorinating agent is preferably 0.02 mmol / L to 2 mol / L, more preferably about 2 mmol / L.

In addition, the concentration of the catalyst in the Friedel-Crafts reaction for surface fluorination reforming is possible in a chemical equivalent of 0.1 to 10 to the number of moles of the fluorinating agent used, preferably 1.0 to 3.0 to the number of moles of the fluorinating agent.

In addition, the Friedel-Crafts reaction temperature is -80 ℃ to 250 ℃, preferably 0 ℃ to 25 ℃.

According to one embodiment of the present invention, a method for producing a surface fluorinated modified electrolyte membrane through Friedel-Crafts reaction is as follows.

Non-fluorine or partially fluorinated hydrocarbon-based segmented block copolymer electrolyte membrane is vacuum dried at a temperature of about 120 ℃. After anhydrous CHCl ₃ was added to the dried reactor in nitrogen atmosphere, the temperature of the reactor was maintained at about 0 ° C. using ice water. A fluorinating agent and a catalyst are added to a reaction vessel in a nitrogen atmosphere, and then the reactant is stirred at 0 ° C. for about 30 minutes to induce the formation of a stabilized acyl cation, which is an electron affinity. After adding the dried non-fluorine or partially fluorinated hydrocarbon-based segmented block copolymer electrolyte membrane to the reaction product, the temperature of the reaction tank is gradually raised to room temperature, and the stirring is maintained. It takes about 30 minutes to raise the temperature of the reactor from 0 ° C. to room temperature, and the temperature of the reaction is raised from 0 ° C. to room temperature to complete the surface fluorination reforming reaction. The surface fluorinated modified electrolyte membrane may be removed from the reaction tank, washed two to three times in ultrapure water, and then dried to prepare a surface fluorinated modified non-fluorine or partially fluorinated hydrocarbon-based segmented blockcopolymer electrolyte membrane.

According to the present invention, a Nafion Ionomer solution is coated on a catalyst layer formed on an electrode support to prepare a cathode and an anode, respectively, and surface fluorination between the cathode and the anode through thermal compression. A membrane-electrode assembly (MEA) may be prepared by interposing a modified polymer electrolyte membrane.

At this time, the coating amount of the ionomer solution is preferably 0.05 ~ 1 mL / cm ² , the pressure at the time of thermal compression is 0.5 ~ 2 tons (ton), the temperature is preferably 100 ~ 150 ℃.

Non-fluorinated hydrocarbon-based polymer electrolyte membrane or partially fluorinated hydrocarbon-based polymer electrolyte membrane is generally incompatible with Nafion ionomer used as coating liquid on catalyst layer or binder of catalyst layer, resulting in poor adhesion between electrolyte membrane and electrode when driving fuel cell. On the other hand, the surface fluorinated modified non-fluorinated hydrocarbon-based polymer electrolyte membrane or surface fluorinated-modified partially fluorinated hydrocarbon-based polymer electrolyte membrane prepared according to the present invention has improved compatibility with the Nafion ionomer between the electrolyte membrane and the electrode in the MEA manufacturing Bonding force is improved.

In addition, the MEA to which the surface fluorinated modified non-fluorinated hydrocarbon-based polymer electrolyte membrane or surface fluorinated-modified partially fluorinated hydrocarbon-based polymer electrolyte membrane is applied provides a polymer electrolyte fuel cell having improved performance and excellent durability.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Example  One. Sulfonation  Hydrocarbon Partial Polyether ketone [ Sulfonated  and Segmented Poly (ether ketone) s] block polymer electrolyte membrane, s -PEEK Surface fluorination modification of, 1

Sulfonated and segmented polyether ketones (Sulfonated and Segmented Poly (ether ketones)) block polymer electrolyte membrane consisting of hydrophilic and hydrophobic blocks having a size of 10 cm × 10 cm and having a thickness of 50 µm were subjected to 6 hours at 120 ° C. The above-mentioned vacuum drying was carried out to remove the water contained in the electrolyte membrane. After adding 1 L of anhydrous CHCl ₃ to a 2 L scale dried reactor under nitrogen atmosphere, the temperature of the reactor was maintained at about 0 ° C. using ice water. 1.00 g (2.31 mmol) of fluorinating agent: Pentadecafluorooctanoyl chloride, 0.37 g (2.77 mmol) of catalyst-AlCl ₃ was added to a reactor in a nitrogen atmosphere, the reaction was stirred at 0 ° C. for about 30 minutes, and then dried sulfonated hydrocarbon system. Sulfurated and Segmented Poly (ether ketones) block polymer electrolyte membranes were immersed in the reactants, and the temperature of the reactor was gradually raised to room temperature while stirring was maintained. The temperature of the reactor was gradually raised to room temperature to complete the surface fluorination reforming reaction. The surface fluorinated modified electrolyte membrane was removed from the reaction tank, washed two to three times in ultrapure water, and then dried to dry the surface fluorinated sulfonated / segmented polyether ketone block polymer. the electrolyte membrane, SG- s -PEEK1, Was prepared.

Example  2. Sulfonation  Hydrocarbon Partial Polyether ketone [ Sulfonated  and Segmented Poly (ether ketone) s] block polymer electrolyte membrane, s -PEEK , Surface fluorination modification 2

Sulfonated and segmented polyether ketones composed of the same electrolyte membrane, that is, a hydrophilic block and a hydrophobic block, in the same manner as in Example 1 except that Perfluoro-1,10-decanedianoly chloride was used as the fluorinating agent. (ether ketone) s] the surface-modified using a fluorinated polymer electrolyte membrane blocks sulfonated / graft hydrocarbon-based part poly ether ketone [sulfonated and Segmented poly (ether ketone ) s] block polymer electrolyte membrane, SG- s -PEEK2 Was prepared.

Example 3 Sulfonated Poly (ether ketones) Polymer Electrolyte Membrane, hs -PEEK , Surface fluorination modification 3

The sulfonated hydrocarbon polyether ketones composed of hydrophilic blocks were used for the surface fluorination modification in the same manner as in Example 1, and the sulfonated hydrocarbon polyether ketone was used as the result. [Sulfonated Poly (ether ketone) s ] a polymer electrolyte membrane, SG- hs -PEEK2, Obtained.

Example 4 Sulfurated Poly (ether ketones) Polymer Membrane, h -PEEK , Surface fluorination modification 4

The surface fluorination was modified in the same manner as in Example 1 using a hydrocarbon-based polyether ketone polymer membrane composed of only a few blocks. The polymer membrane was added to a fluorinating agent and an AlCl ₃ -containing CHCl ₃ solution, but upon stirring, the polymer membrane was dissolved in a solvent. From this, it was confirmed that the hydrocarbon-based polyether ketone polymer membrane composed of only hydrophobic blocks could not be dissolved in the Cl solvent to maintain the membrane form.

Example  5. Preparation of membrane-electrode assembly (MEA)

Sulfonated and Segmented Poly (ether ketones) Block Polymer Electrolyte Membranes ( s -PEEK ), Surface Fluorinated Modified Sulfonated / Graft Hydrocarbon Part Sulfurated and Segmented Poly (ether ketones) Block Polymer Electrolyte Membranes ( SG- s -PEEK1, SG- s -PEEK2) , Sulfonated Poly (ether ketones) Polymer Electrolyte Membrane (hs-PEEK), Sulfonated Poly (ether ketones) polymer electrolyte membrane ( SG - hs - PEEK2 ) as a result of the fluorination reforming reaction, and a catalyst layer on a 3 cm × 3 cm carbon paper, the Nafion ionomer An anode and a cathode coated with (Nafion Ionomer) were prepared. After stacking the two electrodes in the order of the anode-electrolyte-film-reduction electrode, the two electrodes were sandwiched between the plates of a hot press at 140 ° C., and pressed for 5 minutes at a pressure of 1 ton. The conjugate was taken out and cooled in air to produce a MEA.

Using the prepared MEA, the adhesion test between the membrane and the electrode, and the performance of the hydrogen ion exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) were measured in the following manner.

Experimental Example  1.Adhesion test between membrane and electrode of MEA

Each MEA prepared in Example 5 was supported in 100 mL of distilled water and 100 mL of methanol, respectively, to determine whether the membrane and the electrode were separated over time. As a result, the electrolyte membrane s -PEEK , hs -PEEK , And each made from SG- hs -PEEK2 MEA-a1, a2-MEA, MEA-a3, on the other hand when carrying in distilled water and methanol, the membrane and the electrode is separated immediately observed, the electrolyte membrane SG- s -PEEK1 and SG - s each MEA-b1, b2-MEA produced from -PEEK2 was checked for 100 hours is not a film and the electrodes even after separation (Figure 2).

MEA-a3 prepared from the surface fluorination reforming reaction of sulfonated poly (ether ketones) polymer electrolyte membrane composed only of hydrophilic block, hs- PEEK , (Example 3) was prepared in distilled water and methanol. When supported, membrane and electrode separation were immediately observed, so that the surface fluorination reforming reaction of sulfonated poly (ketone) polyether ketones composed of hydrophilic blocks only, hs- PEEK , did not proceed. Could confirm.

On the other hand, the surface fluorination modification reaction of sulfonated and segmented poly (ketone) s block polymer electrolyte membrane composed of hydrophilic block and hydrophobic block was performed in each MEA-b1 prepared from Experimental Example 1. , When MEA-b2 was supported in distilled water and methanol, it was confirmed that the surface fluorination reforming reaction was successful by confirming that the membrane and the electrode were not separated even after more than 100 hours.

Experimental Example  2. Hydrogen ion Exchange membrane  Fuel cell PEMFC A) performance and durability evaluation

Each MEA prepared in Example 5 was assembled into a single cell of a hydrogen ion exchange membrane fuel cell, and the unit cell temperature was 70 ° C., and the flow rates of H ₂ and air were 300 sccm and 1200 ccm, respectively. The temperature of the bubbler line of the anode was maintained at 80 ° C. and 85 ° C., respectively, and the performance of the hydrogen ion exchange membrane fuel cell was evaluated under 100% humidification conditions. The fuel cell to which MEA prepared from electrolyte membrane s - PEEK was applied showed lower performance than the fuel cell to which MEA prepared from electrolyte membranes SG- s -PEEK1 and SG- s -PEEK2 was applied (FIG. 3). , the constant current mode (@ 0.6 V / cm ²⁾ in long-term durability evaluation when the electrolyte membrane of the fuel cell -PEEK s voltage drop is applied is large, while the electrolyte membrane SG- s -PEEK1, SG- -PEEK2 s is applied to the fuel cell Showed stable performance (FIG. 4).

Experimental Example  3. Direct methanol fuel cell performance

The MEA prepared in Example 5 was directly assembled to a unit cell of a methanol fuel cell, and performance was measured under the conditions shown in Table 1 below, and the output density was evaluated under the following conditions. The fuel cell to which the MEA prepared from the electrolyte membrane s -PEEK was applied showed lower performance than the fuel cell to which the MEA prepared from the electrolyte membranes SG- s -PEEK1 and SG- s -PEEK2 was applied (FIG. 5).

Working temperature 80 ℃ Catalyst usage 2 mg / cm 2 fuel 2 M CH ₃ OH Oxygen 1000 kPa / min 1kfg Pressurized

According to the present invention, a sulfonated non-fluorine or partially fluorinated hydrocarbon-based segmented blockcopolymer electrolyte membrane having a fluorinated surface and a fuel cell to which the modified electrolyte membrane is applied are hydrocarbon-based electrolyte membranes which are not subjected to surface fluorination modification. Compared to the membrane, the adhesion between membrane and electrode is better than that of fuel cell, which improves the performance of fuel cell by reducing the interface resistance between electrolyte membrane and electrode. The performance of the fuel cell is maintained and effective for long-term and stable operation.

Although only described in detail with respect to the described embodiments of the present invention, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, it is natural that such variations and modifications belong to the appended claims. .

Claims (24)

A polymer comprising a portion in which a covalent bond in a polymer is maintained while the Cl solvent is infiltrated into the polymer without dissolution in the Cl solvent, and thus includes a portion swelled to a micro-domain size by the Cl solvent. The polymer is characterized in that the fluorination chemistry is modified to be limited to the swelling portion. delete The polymer according to claim 1, wherein the portion swelled by Cl solvent does not include at least one hydrophilic functional group selected from the group consisting of sulfonic acid groups, phosphoric acid groups and carboxylic acid groups. The part of claim 1, wherein the covalent bond in the polymer is maintained while the Cl solvent is infiltrated into the polymer without dissolution in the Cl solvent, thereby swelling to a micro-domain size by the Cl solvent. The polymer comprising a sulfonic acid group-containing partially hydrocarbon-based block polymer, wherein the sulfonic acid group-containing partially hydrocarbon-based block polymer is characterized in that the swelling portion is modified by a fluorination chemical reaction. The polymer according to any one of claims 1, 3 and 4, characterized in that it is in the form of a film. A sulfonated hydrocarbon-based segmented blockcopolymer electrolyte membrane comprising a hydrophilic block containing a sulfonic acid group and a hydrophobic block containing no sulfonic acid group, wherein only a hydrophobic block containing no sulfonic acid group is contained by a Cl solvent. An electrolyte membrane characterized by swelling and surface fluorination modification by fluorination chemical reaction. delete 7. The electrolyte membrane according to claim 6, wherein the surface fluorination modification is a grafting bond of a fluorine-substituted or fluorine-containing compound. 7. The electrolyte membrane according to claim 6, wherein the sulfonated hydrocarbon-based partially blocked polymer electrolyte membrane is not dissolved in a Cl solvent. The electrolyte membrane of claim 6, wherein the sulfonated hydrocarbon-based partially blocked polymer electrolyte membrane to be subjected to surface fluorination is a non-fluorinated sulfonated hydrocarbon-based polymer electrolyte membrane or a partially fluorinated sulfonated hydrocarbon-based polymer electrolyte membrane. The polymer material of the sulfonated hydrocarbon-based partial block polymer electrolyte membrane to be subjected to surface fluorination is sulfonated polyarylene ether, sulfonated polyimide, sulfonated polyamide, sulfonated polyphosphazene, sulfonated Selected from the group consisting of polystyrene, sulfonated radiation-grafted FEP-g-polystyrene, sulfonated radiation-grafted ETFE-g-polystyrene, sulfonated radiation-grafted LDPE-g-polystyrene, sulfonated radiation-grafted PVDF-g-polystyrene Electrolyte membrane, characterized in that the block copolymer (Block copolymer), multiblock copolymer (Grafting copolymer) comprising at least one polymer. The polymer material of the sulfonated hydrocarbon-based partially blocked polymer electrolyte membrane to be subjected to surface fluorination is sulfonated radiation-grafted FEP-g-polystyrene electrolyte membrane, sulfonated radiation-grafted ETFE-g-polystyrene electrolyte membrane An electrolyte membrane characterized by being a sulfonated radiation-grafted LDPE-g-polystyrene electrolyte membrane and a sulfonated radiation-grafted PVDF-g-polystyrene electrolyte. Chemically polymerizes a polymer containing a portion swelled to a micro-domain size by Cl solvent while maintaining the covalent relationship in the polymer while the Cl solvent penetrates into the polymer without dissolution in the Cl solvent. A first step of immersing in a Cl-based solvent containing a reactant, wherein the chemical reaction is limited to the swelling portion to produce a modified polymer. 15. The method of claim 13, comprising a first step of immersing a sulfonated hydrocarbon-based segmented blockcopolymer membrane in a Cl-based solvent containing a fluorinating agent, wherein the surface fluorinated modified sulfide only contains a minor block that does not contain sulfonic acid groups. Method for producing a phonated hydrocarbon-based polymer membrane. The method according to claim 13 or 14, characterized in that it is modified by grafting. The method of claim 14, wherein the Friedel-Crafts reaction occurs in the first step. The method of claim 16, wherein at least one selected from the group consisting of SnCl ₄ , FeCl ₃ , and AlCl _{3 is used} as a catalyst for the Friedel-Crafts reaction. The method according to claim 14, wherein in the first step, a solvent containing at least one selected from the group consisting of CCl ₄ , CHCl ₃ , CH ₂ Cl ₂ , nitrobenzene, and Freon is used. The method according to claim 14, wherein the fluorinating agent is selected from at least one compound group represented by the following formula (1). [Formula 1]

Where A ¹ is

,

,

,

Or a halogen element; X ₁ is a halogen element, a C1 to C12 all fluorine or partially fluorine alkyl group, C2 to C12 all fluorine or partially fluorine alkenyl group, or

Wherein R ¹ to R ⁵ are each independently hydrogen, a halogen element, a C1 to C12 all fluorine or partial fluorine-based alkyl group, C2 to C12 all fluorine or partially fluorine alkenyl group; G ₁ is hydrogen, an alkyl group or a phenyl group; Each B is independently -CD ₁ D _2- ,

Or a combination thereof; Where D ₁ , D ₂ Are each independently hydrogen, halogen, hydroxyl,

, or

And m is an integer from 1 to 6; E is a direct bond, -O-, -S-, -CO-, -SO _2- , -C (CH ₃ ) _2- , or -C (CF ₃ ) _2- , R ⁶ to R ⁹ each independently represents hydrogen, a halogen element, a C1-C12 all-fluorine or partially fluorine-based alkyl group, and C2-C12 all-fluorine or partially fluorine-alkenyl group; n is an integer from 1 to 24; A ² are each independently

,

,

,

Or a halogen element, X ₂ is a halogen element, and G ₂ is hydrogen, a C1-C12 alkyl group or a phenyl group. The method of claim 14, wherein the concentration of the fluorinating agent is from 0.02 mmol / L to 2 mol / L. The method of claim 16, wherein the catalyst concentration of the Friedel-Crafts reaction is a chemical equivalent of 0.1 to 10 relative to the number of moles of the fluorinating agent used. The method of claim 16, wherein the Friedel-Crafts reaction temperature is -80 ℃ to 250 ℃. Cathode; An anode; A membrane-electrode assembly (MEA) comprising the surface fluorinated modified polymer electrolyte membrane according to any one of claims 6 and 8 to 12 interposed between the cathode and the anode. A fuel cell comprising the membrane-electrode assembly of claim 23.

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