KR20040042195A - Polyelectrolyte nanocomposite membrane and the preparation method thereof and the fuel cell using the prepared polyelectrolyte nanocomposite membrane - Google Patents

Abstract

PURPOSE: A polymer nanocomposite membrane and a manufacturing method thereof are provided to reduce the cross-over causing the deterioration of the performance of a fuel cell, and to produce a polymer electrolyte fuel cell having a high electric power density. CONSTITUTION: The polymer nanocomposite for a fuel cell comprises a hydrogen ion-conductive polymer and a layered double hydroxide, wherein the layered double hydroxide is present in an amount of 0.3-10 wt% based on the dry weight of the hydrogen ion-conductive polymer. The method for manufacturing the polymer nanocomposite comprises the steps of: (a) forming solution containing a mixture of the layered double hydroxide and the hydrogen ion-conductive polymer; and (b) performing volatilization of the solvent in the solution to obtain the polymer nanocomposite.

Description

Polymer nanocomposite membrane for fuel cell, manufacturing method thereof and fuel cell using the same {Polyelectrolyte nanocomposite membrane and the preparation method etc. and the fuel cell using the prepared polyelectrolyte nanocomposite membrane}

The present invention relates to a polymer nanocomposite membrane for a fuel cell, a manufacturing method thereof, and a fuel cell having the same.

Fuel cell is a power generation device that converts chemical energy of fuel directly into electric energy by electrochemical reaction, and has higher power generation efficiency than other power generation devices such as diesel power generation and steam gas turbine device. This has a small advantage. The use of such fuel cells is a way to actively cope with international environmental regulations such as climate agreements, and is expected to be an alternative power source in countries with insufficient resources such as Korea.

Among the fuel cells, the polymer electrolyte fuel cell (hereinafter abbreviated as "PEFC") has lower operating temperature, higher efficiency, higher current density, higher output density, and shorter startup time than other fuel cells. Therefore, the response to load change is fast. In addition, since the polymer membrane is used as the electrolyte, there is no need for corrosion and electrolyte control, the design is simple, the manufacturing is easy, and the volume and weight are smaller than those of the phosphate fuel cell having the same operation principle. Compared with the secondary battery developed as a power source for electric vehicles, the specific energy density of the polymer electrolyte fuel cell is 200 Wh / kg to thousands of Wh / kg or more, and is higher than the secondary battery having a value of 200 Wh / kg or less. It has a high advantage. In addition, in terms of charging time, the lithium-based battery requires about 3 hours of charging time, whereas the methanol fuel cell power supply to be developed in this study has a big advantage because it takes only a few seconds to inject methanol fuel. Can be. Accordingly, research and development of polymer electrolyte fuel cells has been actively conducted worldwide as transportation power sources, mobile and emergency power sources, and military power sources that replace batteries of electric vehicles.

The battery is composed of a membrane-electrode assembly (hereinafter, abbreviated as "MEA") formed by stacking a cathode, an anode, and a polymer electrolyte membrane, a fuel channel formed on one side of the cathode, and an air channel formed on one side of the anode. It is a general structure.

The electrode consists of a gas diffusion layer and a catalyst layer. The gas diffusion layer has a porosity of 80% or more, and a material capable of smoothly accessing the fuel and the reactor gas to the catalyst layer is suitable, and serves to connect the current generated during the electrochemical reaction with an external electric circuit. In general, carbon paper or carbon fiber fabric is used as a substrate for the gas diffusion layer. At the cathode, methanol and water are impregnated with a copolymer containing a low content of polytetrafluoroethylene (PTFE) or PTFE in order to facilitate access to the catalyst bed, while at the anode the flooding of water generated during the reaction is prevented. In order to prevent the positive electrode substrate from being hydrophobic, the positive electrode substrate is impregnated with PTFE in an amount of about 10 to 40% based on the weight of the substrate, and then calcined at 340 to 370 ° C to form a cathode and an anode gas diffusion layer.

Cathode and anode catalyst layers are widely distributed with homogeneous or heterogeneous platinum group catalysts on the surface of conductive carbon, which can cause decomposition reactions of methanol and reduction reactions of oxygen, respectively.The reaction efficiency is increased by increasing the specific surface area of the catalysts. In order to improve the efficiency of carbon black, carbon nanotube (carbon nanotube) or carbon nanohorn (carbon nanohorn) such as a method of supporting the catalyst on a very finely divided carbon surface has been actively studied. The catalyst layer of the negative electrode and the positive electrode comprises the steps of (i) homogeneously dispersing the water-soluble proton conductive material capable of conducting the water-soluble protons generated as a result of the catalytic reaction in the polymer electrolyte membrane in a solvent to prepare a catalyst ink, and (ii) the catalyst prepared The ink is applied to the gas diffusion layer or the polymer electrolyte membrane evenly by printing, spraying, rolling or brushing, and (iii) drying the resultant to form a catalyst layer. Are manufactured. The method of preparing the catalyst ink and the method of applying the catalyst layer are one of the biggest variables that influence the battery characteristics, and the method of increasing the reaction efficiency of the catalyst determines the performance of the battery.

International Patent Application Publication No. WO97 / 23919 describes a method of continuously joining a polymer electrolyte membrane, a catalyst layer and a gas diffusion layer in a roller process, and US Patent No. 6,074,692 discloses an electrochemical catalyst ink. The method of apply | coating to both surfaces of a polymer electrolyte membrane simultaneously, without apply | coating to a diffusion layer, etc. are described. In addition, US Patent Application Publication No. 2000-58668 (2000.10.05) discloses a method of directly coating a catalyst ink on a carbon support, which is a gas diffusion layer.

On the other hand, in order to cause continuous electrochemical reaction inside the cell, the MEA should be properly stacked inside the cell, and a bipolar plate for fuel supply and a reactor gas supply is placed on the outer surface of the gas diffusion layer of the cathode and anode, respectively. This serves to distinguish between MEAs and to connect electrons generated by electrochemical reactions to external circuits. The bipolar plate is made of metal or graphite, such as stainless steel, which has excellent electrical conductivity. A flow path through which fuel and a reactant flows is formed on the plate.

On the other hand, the polymer electrolyte membrane constituting the battery is an insulator for electrons and a conductor for hydrogen ions. In general, the thinner the membrane, the lower the overvoltage caused by the ohmic voltage drop (IR drop), and the smaller the equivalent weight, the better the ion exchange ability. It can be called an electrolyte membrane having physical properties. However, if the membrane is too thin, the mechanical strength is weakened, and the gas supplied to both poles penetrates the membrane and crossover occurs to the other pole, which degrades the membrane performance. Too little equivalent weight causes flooding. This will reduce the performance of the membrane. Narayanan et al. Have the advantage that the electrolyte membrane itself has a small equivalent weight, but when the substance having a small equivalent weight is used for the electrolyte membrane used for the electrode, the membrane's activity is reduced by flooding, so the polymer electrolyte membrane has a large equivalent weight. Has been reported to favor cell performance (Narayanan, SR, "Implications of methanol crossover in direct methanol fuel cells", DOE / ONR Fuel Cell Workshop Baltimore , Oct 6-8, 1999). Currently, Nafion polymer membrane, which is a commercially available hydrogen ion conductive polymer membrane, is a major obstacle to commercializing the PEFC as a power source for power generation due to the crossover phenomenon of the reaction fuel. Reaction fuel crossover is a phenomenon in which fuel is not completely oxidized when fuel is injected into the anode (cathode), and the fuel crosses from the anode to the cathode (anode). The over phenomenon is shown in FIG. Methanol crossover is the biggest challenge to overcome in direct methanol fuel cells. Crossover phenomenon results in over 20% fuel loss and over 0.1V voltage loss (Deluga, G., Pivovar, BS and Shores, DA, " Composite Membranes in Liquid Feed Direct Methanol Fuel Cells ", DOE / NRL Fuel Cell Workshop Baltimore , Oct 6-8, 1999).

To solve the crossover phenomenon, use Gore-Select, a reinforced composite polymer membrane made of PTFE and a fluoroionomer, or use a hydrophobic porous membrane on the polymer electrolyte membrane. Many studies have been conducted on the development of more excellent membranes, such as the production of composite membranes, and the development of hydrocarbon membranes that can replace conventional fluorine-containing membranes.

An object of the present invention is to provide a polymer nanocomposite membrane for producing a PEFC having a high power density by increasing the energy density of the PEFC by reducing the crossover phenomenon of the fuel which is the main cause of the fuel cell performance degradation, and a method of manufacturing the same.

1 illustrates a crossover phenomenon of methanol in a direct methanol fuel cell,

2 is a manufacturing process chart of the polymer nanocomposite membrane of the present invention,

3 is a block diagram of an electrode-membrane assembly using the polymer nanocomposite membrane of the present invention,

Figure 4 shows a methanol permeation measuring device,

5 is a graph comparing the change in time versus methanol crossover between the polymer nanocomposite membrane and the commercial Nafion polymer membrane of the present invention,

6 is a graph comparing the diffusion coefficient of the polymer nanocomposite membrane and the commercial Nafion polymer membrane of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: polymer nanocomposite film 102 of the present invention: anode

104: cathode 106: metal mesh

In order to achieve the above object, the present invention provides a polymer nanocomposite membrane in which a layered double hydroxide (hereinafter, referred to as "LDH") is dispersed in a hydrogen ion conductive polymer.

The hydrogen ion conductive polymer is preferably a fluorine-based polymer, and is commonly used Nafion ionomer (Nafion). ionomer, DuPont) is more preferred.

LDH is also referred to as anionic clay minerals or hydrotalcite-like compounds, which may exist naturally in some regions and are easily synthesized, represented by the general formula Can be.

[Formula 1]

[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^{x +} [(X ^m- ) _{x / m} nH ₂ O] ^x-

^Wherein x = [M ³⁺ ] / ([M ²⁺ ] + [M ³⁺ ]),

M ²⁺ is Mg ²⁺ , Zn ²⁺ , or Ni ²⁺ ,

M ³⁺ is Al ³⁺ , Cr ³⁺ or Fe ³⁺ ,

X ^m- is _{^{CO 3 2-, Cl -, OH}} -, NO 3 -, PO 4 3-, CrO 4 2-, Fe (CN) 6 3-, Mo 7 O 24 6- or V ₁₀ O ₂₈ ^6- to be.

LDH is crystallographically substituted with trivalent metals, such as Al ³⁺ and Fe ³⁺ , in which the divalent metals are partially sized in hydroxides such as Mg ²⁺ and Ni ²⁺ that have a CdI ₂ structure and form an octahedral layer. As a result, the charge is positively charged due to the lack of charge in the layer, and an anion such as CO ₃ ^2- or OH ^- is interrupted between the layers to offset the positive charges thus generated, and the water layer coordinates the layer structure. Will form.

In Formula 1, the content ratio of M ²⁺ and M ³⁺ is preferably in a molar ratio of 1: 1 to 10, and M ²⁺ is preferably Mg ²⁺ and M ³⁺ is Al ³⁺ .

However, the LDH used in the present invention is not limited to the above description, and any material that forms a double layer may be used.

In the present invention,

(a) obtaining a mixed solution of a layered double hydroxide and a hydrogen ion conductive polymer,

(b) providing a method for preparing a polymer nanocomposite membrane comprising volatilizing a solvent of the solution to obtain a polymer composite membrane.

The manufacturing method is shown in FIG. 2 as an example using Nafion ionomer as a hydrogen ion conductive polymer. As shown in Figure 2, the step (a),

(i) dissolving LDH in a predetermined solvent to prepare an LDH solution;

(ii) volatilizing the solvent of the Nafion ionomer solution at room temperature;

(iii) dissolving the Nafion ionomer in which the solvent is volatilized in the same solvent as the solvent of the LDH solution to prepare a Nafion ionomer solution; And

(iv) mixing the LDH solution and the Nafion ionomer solution with each other.

Although FIG. 2 is shown to include volatilizing the solvent first using a Nafion ionomer solution as a raw material (step ii), when using a solid Nafion ionomer as a raw material (ii) ) Step can be omitted.

In the mixed solution composition, LDH is preferably 0.3 to 10% by weight based on the weight of the Nafion ionomer.

The amount of the solvent used may be such that Nafion ionomer and LDH can be uniformly mixed. Although not particularly limited, the solvent is used at about 60 to 99% by weight based on Nafion ionomer.

The solvent of the Nafion ionomer and LDH mixed solution is a solvent that allows LDH to be well dispersed in the Nafion ionomer, and a mixed solvent of a lower alcohol and DI water is preferable, and more preferably 1- A mixed solvent of propanol, 2-propanol, methanol and deionized water is used. It is preferable that these composition ratios are 10-40: 10-40: 5-20: 5-20 by volume ratio.

In addition, the step (b) includes the step of volatilizing the solvent of the mixed solution to obtain a polymer nanocomposite membrane containing Nafion ionomer and LDH, and then additionally heating the resultant if necessary (see FIG. 2). . The reason for the additional heating is to crystallize the linear structure of the polymer obtained by volatilizing the solvent of the mixed solution to prevent the finally obtained polymer film from being easily damaged, such as being dissolved by the solvent. At this time, it is preferable that heating temperature is 60-120 degreeC.

After the step (b), the prepared polymer nanocomposite membrane may further comprise a step of hydrating using a mixed solution of potassium hydroxide, dimethyl sulfoxide and tertiary distilled water. This process removes impurities generated in the manufacturing process of the polymer nanocomposite membrane and plays a role of facilitating hydrogen ion conduction when mounted in a battery.

The diffusion coefficient of the polymer nanocomposite membrane prepared in the present invention with respect to methanol is 4 × 10 ⁻⁷ cm 2 / S or less, preferably 1 × 10 ⁻⁷ to 4 × 10 ⁻⁷ cm 2 / S, and these values are commercially available. The crossover phenomena of methanol in the fuel cell can be greatly reduced to a value smaller than the diffusion coefficient (4.47 × 10 ⁻⁷ cm 2 / S) of the Nafion polymer membrane.

In addition, the present invention provides a MEA comprising the above-described polymer nanocomposite membrane of the present invention, specifically, the MEA of the present invention is bonded to the negative electrode formed on one side of the polymer nanocomposite membrane, the other side of the polymer nanocomposite membrane Contains an anode.

As described above, the cathode and the anode are each composed of a gas diffusion layer and a catalyst layer.

As the base material of the gas diffusion layer, carbon paper or carbon fiber fabric is generally used, and a material having a porosity of 80% or more and capable of smoothly accessing the fuel and the reactor gas to the catalyst layer is preferable. The gas diffusion layer connects the current generated during the electrochemical reaction with an external electric circuit. In the negative electrode, in order to facilitate access to the catalyst layer, methanol and water are preferably impregnated with 0 to 10% by weight of PTFE or a copolymer including the same to the substrate to form a gas diffusion layer of the negative electrode. On the anode side, PTFE is impregnated into the substrate at 10 to 40% by weight based on the weight of the substrate in order to increase the hydrophobicity to prevent the overflow of water generated during the reaction, and then fired at 340 to 370 ° C. to form a gas diffusion layer of the anode.

Cathode and anode catalyst layers are used in the form of evenly distributed homogeneous or heterogeneous platinum group electrocatalysts on the surface of conductive carbon, which can cause decomposition reactions of methanol and reduction reactions of oxygen, respectively. It is preferable to use a Pt catalyst and a mixed catalyst of Pt and Ru, for example, a Pt / Ru (50:50) catalyst, in the catalyst layer of the cathode. In addition to Pt / Ru, Pt / Ir, Pt / Ru / Ir or a mixed catalyst of these and Ti may be used. The mixing ratio of Pt and other catalyst components can be appropriately adjusted according to the use of the electrode.

The catalyst layer of the cathode and the anode comprises (i) preparing a catalyst ink mainly composed of the catalyst as described above, and (ii) printing, spraying and rolling the prepared catalyst ink evenly on the gas diffusion layer or the polymer nanocomposite membrane of the present invention. Or by applying a brushing method and (iii) drying the resultant to form a catalyst layer.

In addition, a conventional electrode may be bonded to the polymer nanocomposite membrane according to the present invention to form an MEA.

The structural example of the MEA manufactured by this invention is shown in FIG. MEA is prepared by arranging the cathode 102 on one side of the polymer nanocomposite membrane 100 for fuel cells prepared by the method of the present invention and the anode 104 on the other side, and then heating and pressing them to combine them. At this time, the polymer nanocomposite membrane 100 is interposed therebetween and arranged so that the catalyst layers of the cathode and the anode face each other. That is, a catalyst layer is formed on the bonding surface of the cathode 102 and the polymer nanocomposite membrane 100 and the bonding surface of the anode 104 and the polymer nanocomposite membrane 100. On the other hand, a metal mesh 106 is attached to the outer surfaces of the gas diffusion layers of the cathode 102 and the anode 104 to be used as an electric passage.

In addition, the present invention provides a polymer electrolyte fuel cell employing the MEA.

Hereinafter, the present invention will be described in detail by examples. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

Example 1 Preparation of Polymer Nanocomposite Membranes of the Invention (1)

(1) Preparation of Nafion Ionomer Solution

Nafion Ionomer Solution (Nafion After 10 g of perfluorinated ion-exchange resin (Dupont) was left at room temperature for 48 hours to evaporate all the solvents, the solvent-volatile Nafion ionomer was added with 1-propanol, 2-propanol, methanol and deionized water (DI water). It dissolved in 50 mL of the mixed solvent in the ratio of 2: 2: 1: 1.

(2) Preparation of LDH Solution

2.56 g of Mg (NO ₃ ) ₂ .6H ₂ O and 1.88 g of Al (NO ₃ ) ₃ .9H ₂ O are mixed in 10 mL of H ₂ O, and 0.371 g of Na ₂ CO ₃ is mixed in 17.5 mL of H ₂ O. Combined, NaOH was added to adjust the pH to 10, and the solvent was evaporated to obtain LDH having a content ratio of Al ³⁺ and Mg ²⁺ of 2: 1. The 1-propanol, 2-propanol, methanol, and deionized water were added to 50 mL of a solvent in a volume ratio of 2: 2: 1: 1 so that the LDH weight ratio was 1% based on the dry weight of Nafion ionomer. The solution was prepared.

(3) Preparation of Mixed Solution and Polymer Nanocomposite Membrane

The Nafion ionomer solution prepared in (1) and (2) was mixed with the LDH solution while stirring, and the mixture was left at room temperature for 48 hours to volatilize the solvent, and the remaining film was then heated to 100 ° C. for 24 hours. The polymer nanocomposite membrane of the invention was obtained.

Example 2 Preparation of Polymer Nanocomposite Membranes of the Invention (2)

In the preparation of the LDH solution of the process of Example 1 (2), the same method as in Example 1 except that the content ratio of Al ³⁺ and Mg ²⁺ of the layered double hydroxide is adjusted to 4: 1. The polymer nanocomposite of the present invention was obtained.

Example 3 Preparation of Polymer Nanocomposite Membranes of the Invention (3)

In the preparation of the LDH solution of the process of Example 1 (2), the same method as in Example 1 except that the content ratio of Al ³⁺ and Mg ²⁺ of the layered double hydroxide is 6: 1 The polymer nanocomposite of the present invention was obtained.

Example 4. Preparation of Polymer Nanocomposite Membranes of the Invention (4)

In the process of Example 1 (2), the polymer nanocomposite of the present invention was obtained in the same manner as in Example 1, except that an LDH solution was prepared such that LDH became 3% of the Nafion ionomer dry weight. .

Example 5 Preparation of Polymer Nanocomposite Membranes of the Invention (5)

In the process (2) of Example 1, LDH is adjusted so that the content ratio of Al ³⁺ and Mg ²⁺ is 4: 1, to prepare an LDH solution so that LDH is 3% of the dry weight of Nafion ionomer Except for the polymer nanocomposite of the present invention was obtained in the same manner as in Example 1.

Example 6 Preparation of Polymer Nanocomposite Membranes of the Invention (6)

In the process (2) of Example 1, LDH is adjusted to the content ratio of Al ³⁺ and Mg ²⁺ is 6: 1, to prepare an LDH solution so that LDH is 3% of the dry weight of Nafion ionomer Except for the polymer nanocomposite of the present invention was obtained in the same manner as in Example 1.

Examples 7-12. MEA Production Using Polymer Nanocomposite Membranes of the Present Invention (1) to (6)

(1) Preparation of Cathode Catalytic Ink

90% by weight of Pt / Ru (50:50) catalyst and Nafion ionomer solution (Nafion Perfluorinated ion-exchange resin (Dupont) 10 wt% was added to a mixed solvent of isopropanol and water and uniformly dispersed in an ultrasonic solution disperser to prepare a catalyst ink.

(2) Preparation of Cathode

20 wt% PTFE was treated on the conductive carbon paper substrate to form a gas diffusion layer, and a thin catalyst layer was formed by spray-coating the cathode catalyst ink on one side of the gas diffusion layer to prepare a cathode that causes decomposition reaction of methanol (2cm × 2 cm).

(3) manufacture of positive electrode

Next, after preparing 90% by weight of Pt and 10% by weight of Nafion solution using the same solvent as the cathode, the anode catalyst ink was coated on one side of a gas diffusion layer made of conductive carbon paper treated with 20% by weight of PTFE. After leaving for 4 hours in the oven of the solvent was completely removed to prepare a positive electrode to cause a reduction reaction of oxygen (2cm × 2cm).

(4) manufacturing of MEA

MEA was prepared by laminating the polymer nanocomposite membranes (3 cm × 3 cm) prepared in Examples 1 to 6, respectively, and the positive and negative electrodes obtained in (2) and (3).

At this time, one side of the polymer membrane prepared in Examples 1 to 6 was arranged so as to contact the catalyst layer of the anode, the other side of the catalyst layer, and put between two plates of the hydraulic pressure maintained at a temperature of 140 ℃ to a pressure of 3 tons 5 minutes was pressed to prepare the MEA of the present invention.

Conductive carbon paper of MEA was attached to the outer surface of the nickel mesh (mesh) was used as the passage of electricity.

Comparative Example 1.

As shown in FIG. 4, 0.05 mol of 1-butanol and 2 mol of methanol were added as a reference, and the result was measured by gas chromatography to measure the crossover amount of methanol that permeated the membrane over time. The diffusion coefficient of the membrane was determined using the weight ratio of the concentration of methanol. At this time, the diffusion coefficient of the commercial Nafion polymer membrane (Nafion 115, Dupont) was 4.47 × 10 ⁻⁷ (cm 2 / S).

Experimental Example 1.

Using the polymer nanocomposite membrane prepared in Example 1, the diffusion coefficient was calculated in the same manner as in Comparative Example. The diffusion coefficient of the polymer nanocomposite membrane measured at this time was 3.54 × 10 ⁻⁷ (cm 2 / S).

Experimental Example 2.

Using the polymer nanocomposite membrane prepared in Example 2, the diffusion coefficient was calculated in the same manner as in Comparative Example. The diffusion coefficient of the polymer nanocomposite membrane measured at this time was 2.94 × 10 ⁻⁷ (cm 2 / S).

Experimental Example 3.

Using the polymer nanocomposite membrane prepared in Example 3, the diffusion coefficient was calculated in the same manner as in Comparative Example. The diffusion coefficient of the polymer nanocomposite membrane measured at this time was 2.73 × 10 ⁻⁷ (cm 2 / S).

Experimental Example 4.

Using the polymer nanocomposite membrane prepared in Example 4, the diffusion coefficient was calculated in the same manner as in Comparative Example. The diffusion coefficient of the polymer nanocomposite membrane measured at this time was 2.45 × 10 ⁻⁷ (cm 2 / S).

Experimental Example 5.

Using the polymer nanocomposite membrane prepared in Example 5, the diffusion coefficient was calculated in the same manner as in Comparative Example. The diffusion coefficient of the polymer nanocomposite membrane measured at this time was 2.03 × 10 ⁻⁷ (cm 2 / S).

Experimental Example 6.

Using the polymer nanocomposite membrane prepared in Example 6, the diffusion coefficient was calculated in the same manner as in Comparative Example. The diffusion coefficient of the polymer nanocomposite membrane measured at this time was 1.51 × 10 ⁻⁷ (cm 2 / S).

5 shows a graph of change in time versus methanol crossover for the polymer membranes tested in Comparative Examples and Experimental Examples 1 to 5, and the diffusion coefficient was measured using the graphs.

As described above, the polymer nanocomposite membrane prepared by the present invention has a diffusion coefficient lower than that of the conventional polymer electrolyte by dispersing the layered double hydroxide in the Nafion polymer. Therefore, it is possible to solve the crossover phenomenon of fuel, which is a major cause of deterioration of fuel cell performance. On the other hand, the polymer fuel cell employing the polymer nanocomposite membrane of the present invention has an increased energy density and can have a high power density by using a high concentration of fuel. In addition, it is possible to sufficiently increase the concentration of fuel per unit volume inside the cell, thereby increasing the power density and increasing the life of the cell.

The polymer nanocomposite membrane prepared by the method of the present invention may be applied to a variety of micro fuel cells or fuel cells for small-scale mobile power supplies.

Claims (25)

A polymer nanocomposite membrane for a fuel cell, comprising a hydrogen ion conductive polymer and a layered double hydroxide (Layered Double Hydroxide). The polymer nanocomposite membrane of claim 1, wherein the layered double hydroxide has a content of 0.3 to 10 wt% based on the dry weight of the hydrogen ion conductive polymer. The polymer nanocomposite membrane of claim 1 or 2, wherein the hydrogen ion conductive polymer is a fluorine-based polymer. The method of claim 3, wherein the fluorine-based polymer Nafion ionomer (Nafion polymer nanocomposite membrane for a fuel cell, characterized in that the ionomer). The polymer nanocomposite membrane of claim 1 or 2, wherein the layered double hydroxide is represented by the following Chemical Formula 1. [Formula 1] [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^{x +} [(X ^m- ) _{x / m} nH ₂ O] ^{x- Wherein} x = [M ³⁺ ] / ([M ²⁺ ] + [M ³⁺ ]), M ²⁺ is Mg ²⁺ , Zn ²⁺ , or Ni ²⁺ , M ³⁺ is Al ³⁺ , Cr ³⁺ or Fe ³⁺ , X ^m- is _{^{CO 3 2-, Cl -, OH}} -, NO 3 -, PO 4 3-, CrO 4 2-, Fe (CN) 6 3-, Mo 7 O 24 6- or V ₁₀ O ₂₈ ^6- to be. 6. The polymer nanocomposite membrane of claim 5, wherein M ²⁺ is Mg ²⁺ and M ³⁺ is Al ³⁺ . 7. The polymer nanocomposite membrane of claim 6, wherein the content ratio of M ²⁺ : M ³⁺ is 1: 1 to 10 in molar ratio. The polymer nanocomposite membrane of claim 1, wherein the diffusion coefficient of the polymer nanocomposite with respect to methanol is 4 × 10 ⁻⁷ cm 2 / S or less. The fuel cell polymer nanocomposite membrane according to claim 1 or 2, wherein the diffusion coefficient of the polymer nanocomposite membrane with respect to methanol is 1 × 10 ⁻⁷ to 4 × 10 ⁻⁷ cm 2 / S. (a) obtaining a mixed solution of a layered double hydroxide and a hydrogen ion conductive polymer, (b) volatilizing a solvent of the solution to obtain a polymer composite membrane. The method of manufacturing a polymer nanocomposite membrane for a fuel cell according to claim 10, wherein the hydrogen ion conductive polymer is a Nafion ionomer. 12. The method of claim 10 or 11, wherein step (a) (i) dissolving the layered double hydroxide in a mixed solvent containing a lower alcohol and deionized water (D.I water) to obtain a layered double hydroxide solution; (ii) dissolving Nafion ionomer in the same solvent as the layered dihydroxide solution to prepare a Nafion ionomer solution; And (iii) mixing the layered double hydroxide solution and Nafion ionomer solution dissolved in the solvent with each other. 13. The method of claim 12, wherein the step (a) comprises mixing the layered double hydroxide in the mixed solution so as to be 0.3 to 10% by weight based on the dry weight of the Nafion ionomer. The method of claim 12, wherein the mixed solvent of lower alcohol and deionized water is a mixed solvent of 1-propanol, 2-propanol, methanol, and deionized water. 15. The method of claim 14, wherein the mixed solvent is a solvent in which 1-propanol, 2-propanol, methanol, and deionized water are mixed in a weight ratio of 10 to 40: 10 to 40: 5 to 20: 5 to 20. Method for producing a polymer nanocomposite membrane for a fuel cell. The method of claim 10, further comprising heating the resultant after the solvent volatilization after the step (b). The fuel cell of claim 10, further comprising hydrating the polymer nanocomposite membrane prepared after the step (b) using a mixed solution of potassium hydroxide, dimethyl sulfoxide, and tertiary distilled water. Method for producing a polymer nanocomposite membrane. A polymer nanocomposite membrane comprising a hydrogen ion conductive polymer and a layered double hydroxide, Membrane-electrode assembly comprising a cathode formed on one side of the polymer nanocomposite membrane and an anode formed on the other side of the polymer nanocomposite membrane. 19. The membrane-electrode assembly of claim 18, wherein an anode catalyst layer is formed on the junction surface of the anode and the polymer nanocomposite membrane, and a cathode catalyst layer is formed on the junction membrane of the cathode and the polymer nanocomposite membrane. 20. The membrane-electrode assembly of claim 19, wherein the anode catalyst layer is a Pt catalyst and the cathode catalyst layer is a Pt / Ru catalyst. A fuel cell employing the membrane-electrode assembly of claim 18. Dispersant solvent, A polymer nanocomposite film composition comprising a hydrogen ion conductive polymer dispersed in the dispersion solvent and a layered double hydroxide, wherein the layered double hydroxide is 0.3 to 10% by weight relative to the hydrogen ion conductive polymer. 23. The polymer nanocomposite membrane composition of claim 22, wherein the dispersion solvent is a mixed solvent of lower alcohol and deionized water. The method of claim 23, wherein the dispersion solvent is a solvent in which 1-propanol, 2-propanol, methanol and deionized water are mixed in a ratio of 10 to 40:10 to 40: 5 to 20: 5 to 20 by weight. Polymer nanocomposite membrane composition for a fuel cell. 23. The polymer nanocomposite membrane composition of claim 22, wherein the solvent is contained in an amount of 60 to 99 wt% based on the hydrogen ion conductive polymer.