KR20140129721A - Proton exchange membrane for fuel cell, preparation method thereof and fuel cell comprising the same - Google Patents

Abstract

The present invention relates to: a polymer electrolyte membrane of a fuel cell which improves the performance of fuel cells by maximizing the reaction area of electrodes and the electrolyte membrane of polymers to enlarge the three-phase interfaces, in which electrochemical reaction of fuel cells is made; a manufacturing method thereof; and a fuel cell including the same and, more specifically, to a direct methanol fuel cell (DMFC), which is a low temperature fuel cell using the electrolyte membrane of polymers, and polymer electrolyte fuel cells (PEFC).

Description

TECHNICAL FIELD [0001] The present invention relates to a polymer electrolyte membrane for a fuel cell, a method for manufacturing the same, and a fuel cell including the membrane,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte membrane of a fuel cell, a method of manufacturing the same, and a fuel cell including the polymer electrolyte membrane. More particularly, A direct methanol fuel cell (DMFC), which is a low-temperature type fuel cell using a polymer electrolyte membrane, and a method of manufacturing the same, which can improve the performance of a fuel cell by maximizing a reaction area of the fuel cell, And a polymer electrolyte fuel cell (PEFC).

A fuel cell is a power generation system that directly converts the chemical energy of hydrogen contained in hydrocarbons fuel such as hydrogen, such as methanol, ethanol, and natural gas, and oxygen contained in the air, into electrical energy through an electrochemical reaction.

Such a fuel cell is a clean energy source that can replace conventional fossil energy. When a unit cell is stacked to form a stack and modularized, the fuel cell has an advantage of obtaining a wide range of output from several watts to several hundreds of kilowatts. It has been attracting attention as a compact and mobile power source because it exhibits energy density 4 to 10 times that of a battery.

Fuel cells can be classified into various types depending on the type of electrolyte used, such as a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), a polymer electrolyte fuel cell (PEFC) AFC). Each of these fuel cells basically operates by electrochemical principles, but the type of fuel used, the operating temperature, the catalyst, and the electrolyte are different from each other.

Among the fuel cells, a fuel cell using a polymer membrane as an electrolyte includes a polymer electrolyte fuel cell (PEFC) and a direct methanol fuel cell (DMFC).

Polymer electrolyte fuel cells (PEFCs), which use hydrogen as a fuel, have the advantages of high energy density and high output. However, attention has to be paid to the handling of hydrogen gas. Methane, methanol and natural gas And a fuel reforming device for reforming the fuel and the like.

Direct Methanol Fuel Cell (DMFC) uses the same hydrogen ion conductive polymer membrane as the polymer electrolyte fuel cell, but uses direct methanol fuel as the electrolyte, which is different from the polymer electrolyte fuel cell. Direct methanol fuel cells are capable of starting at room temperature without a fuel reformer and operate at operating temperatures below 100 ° C, making them suitable for portable or small fuel cells.

Direct methanol fuel cells are attracting attention as energy conversion devices that have the advantages of high energy density, low temperature operation, and miniaturization of the system. However, the direct methanol fuel cell has a disadvantage in that it uses much expensive noble metal catalyst due to the low reactivity of liquid methanol and crossover (permeates) from the fuel electrode to the air electrode to degrade the performance of the fuel cell. To overcome these disadvantages, catalyst abatement technology and high performance polymer membrane synthesis technology have been studied extensively.

The basic structure of a direct methanol fuel cell has a fuel electrode (oxidizing electrode) and an air electrode (reducing electrode) on both sides of a polymer electrolyte membrane (usually a Nafion membrane) with a catalytic layer coated on porous carbon paper, A current collector or separator is placed on the electrode.

Direct methanol fuel cells use liquid or solid electrolytes as electrolyte. A liquid electrolyte is used, such as a potassium hydroxide (KOH), sulfuric acid (H ₂ SO _4), the solid polymer membrane such as Nafion is four in the solid electrolyte is used. In the early stage of direct methanol fuel cell development, focusing on fuel cells using liquid electrolyte has been studied. However, due to difficulties in decomposition and concentration control of electrolytes, it is currently difficult to produce solid polymer type direct electrolyte using hydrogen ion- Researches on methanol fuel cells are becoming mainstream.

Direct methanol fuel cells use hydrogen ion exchange polymer membranes that transfer hydrogen ions to the electrolyte. The polymer membrane serves as a carrier of hydrogen ions between the fuel electrode and the air electrode, and serves as a separator for separating fuel and oxygen from each other. Therefore, the polymer electrolyte membrane should have high hydrogen ion conductivity, low electron conductivity, less reactive gas or fuel transfer, and high mechanical and chemical stability.

Conventional studies for improving the performance of direct methanol fuel cells have been carried out in order to improve the electrode performance, such as carbon-supported highly active platinum catalysts (Pt / C, PtRu / C), high conductivity proton conductive polymer membranes And the development of coating technology.

The prior art for improving the performance of a direct methanol fuel cell is as follows.

Korean Patent No. 0534658 discloses a polymer electrolyte composition for a direct methanol fuel cell comprising a perfluoronate-based ionomer (A) having a main chain and a hydrocarbon-based ionomer (B) having a main chain cross-linked.

Korean Patent No. 0746329 discloses that the membrane / electrode assembly (MEA) of a conventional direct methanol fuel cell is subjected to a heat treatment immediately after the thermocompression process to improve the interfacial adhesion between the membrane and the electrode, thereby lowering the battery resistance, Discloses a heat treatment method of a membrane / electrode assembly of a direct methanol fuel cell capable of improving the performance and long-term stability of a fuel cell by enhancing the solubility inhibition and mechanical stability of the fuel cell and maintaining the stability of the binder in the electrode.

Membrane / electrode assemblies of direct methanol fuel cell or polymer electrolyte fuel cell are fabricated by coating and hot pressing an electrode slurry composed of a catalyst and a polymer solution (ionomer). It is difficult to uniformly mix the catalyst and the ion-exchange polymer solution when the electrode slurry is prepared by the conventional method, and it is difficult to artificially control the reaction interface, that is, the triple phase boundary where the electrochemical reaction of the fuel cell occurs. In order to enhance the output characteristics of the fuel cell, it is absolutely necessary to artificially control the structure of the three-phase system to widen the reaction interface.

1, the three-phase system is an electrochemical reaction interface (contact surface of an electrolyte / catalyst / fuel (or air)) in which a hydrogenation reaction (HOR) of a fuel cell or methanol occurs and a reduction reaction (ORR) However, since the three-phase system is a position where the electrochemical reaction of the fuel cell occurs, there is a direct relationship with the performance of the fuel cell. Therefore, in order to improve the performance of the fuel cell, it is necessary to control the three-phase system to form a wide reaction interface.

However, as schematically shown in the mathematical model of FIG. 2 (reference: O'Hayre, J. Electrochemical Society, 152 (2005)), a low temperature type fuel cell using a catalyst such as Pt / C, PtRu / (DMFC, PEFC), it is difficult to control the contact surface of Pt / Nafion due to aggregation of spherical particles.

As shown in FIG. 1, in a three-phase system in which an electrolyte, a carbon-supported platinum catalyst, and a fuel such as hydrogen and methanol are simultaneously contacted, hydrogen or methanol is oxidized by the catalyst to form hydrogen ions (proton) The platinum catalyst at the position where the three-phase system is formed is activated but the platinum catalyst at the position where the three-phase system is not formed is inactivated, making it difficult to participate in the electrochemical reaction of the fuel cell. That is, a platinum catalyst is required to be located at a position of the three-phase system to increase the electrochemical reaction.

 The polymer membrane currently used as the electrolyte of the direct methanol fuel cell is nepion which is commercialized by DuPont. Nepion has a form in which sulfonic acid groups are chemically bonded to fluorohydrocarbons. The equivalent weight of the nepion membrane is 1100-1500, the thickness is 50-175 mm, and it has the same hydrogen ion conductivity as the 1 M sulfuric acid solution. The NEPIONON ion exchange membrane has advantages of high solubility of oxygen, high hydrogen ion conductivity, low density, excellent chemical stability and mechanical strength.

In order to improve the performance of a conventional fuel cell, the present inventors studied a technique of forming a fine pattern on the surface of a polymer membrane in order to artificially control a three-phase system, which is a reaction interface at which an electrochemical reaction of a fuel cell takes place. As a result, It has been found that the reaction area of the polymer membrane and the electrode can be maximized to improve the performance of the fuel cell by forming a microstructure pattern on the membrane surface to enlarge the three-phase system surface.

It is an object of the present invention to maximize the reaction area of the polymer electrolyte membrane and the electrode in order to enlarge the three-phase system (electrolyte / catalyst / fuel (or air)) which is the reaction interface at which the electrochemical reaction of the fuel cell occurs, A direct methanol fuel cell (DMFC) and a polymer electrolyte fuel cell (PEFC), which are low-temperature fuel cells using a polymer electrolyte membrane, and a method for producing the polymer electrolyte membrane, will be.

In order to accomplish the above object, the present invention provides a method for producing a polymer electrolyte membrane, comprising: preparing a polymer electrolyte membrane using a perfluorosulfonylfluoride / TFE copolymer resin (nepion resin); Forming a fine pattern on a surface of the polymer electrolyte membrane by using a stamper, and pretreating the polymer electrolyte membrane. The present invention also provides a method of manufacturing a polymer electrolyte membrane of a fuel cell.

In one embodiment of the present invention, the fine pattern formed on the surface of the polymer electrolyte membrane preferably has a side length of 5 to 50 mu m, an interval of 5 to 50 mu m, and a height of 5 to 30 mu m.

In the present invention, the process of pretreating the polymer electrolyte membrane comprises treating the polymer electrolyte membrane in a mixed solution of caustic soda (NaOH) and methanol (CH ₃ OH) at a weight ratio of 5-30, washing the polymer electrolyte membrane with distilled water and removing impurities with hydrogen peroxide , 0.1-5 M sulfuric acid (H ₂ SO ₄ ) solution, treating with distilled water, and drying the polyelectrolyte membrane.

The present invention also provides a membrane / electrode assembly including a polymer electrolyte membrane produced according to the above-described method, and a fuel cell including the membrane / electrode assembly.

The polymer electrolyte membrane according to the present invention is applied not only to a polymer electrolyte membrane for direct methanol fuel cell (DMFC) but also to a polymer electrolyte fuel cell (PEFC) using hydrogen as a fuel.

The present invention relates to a polymer electrolyte membrane of a fuel cell capable of increasing the performance of a fuel cell by increasing a three-phase system, which is a reaction interface at which an electrochemical reaction of a fuel cell occurs, a membrane / electrode assembly for a fuel cell comprising the same, A direct methanol fuel cell (DMFC) and a polymer electrolyte fuel cell (PEFC), which have remarkably improved output performance compared to the fuel cell of the present invention, can be provided.

1 is a schematic view showing a three-phase system in which an electrochemical reaction takes place in a fuel cell.
2 is a view showing a quaternary space model of the fuel cell 3 upper limit surface.
3 is a schematic view of a stamp produced in the production example of the present invention.
4 is a schematic view illustrating a process of forming a fine pattern on a polymer electrolyte membrane using two stamps in an embodiment of the present invention.
5 is a scanning electron microscope (SEM) photograph of the surface of a nepion membrane having a pattern formed in Comparative Example 1 and Examples 1 to 3 of the present invention.
6 is a scanning electron microscope (SEM) image of a surface of a polymer electrolyte membrane prepared in Example 1 and Comparative Example 1 after coating a catalyst slurry in Test Example 2 of the present invention.
7 is a scanning electron microscope (SEM) image of the surface of the polyelectrolyte membrane prepared in Example 1 and Comparative Example 1 before and after hydration.
8 is a graph showing the results of measurement of the performance of the direct methanol fuel cell manufactured in Examples 1 to 3 and Comparative Example 3 of the present invention.
9 is a graph showing the impedances of the direct methanol fuel cells manufactured in Examples 1 to 3 and Comparative Example 3 of the present invention.
10 is a graph showing current and output increase of a battery according to an increase in surface area of a polymer electrolyte membrane in which fine patterns are formed in Examples 1 to 3 of the present invention.

Hereinafter, a method for producing a polymer electrolyte membrane of a fuel cell according to the present invention will be described in detail.

First, a polyelectrolyte membrane is prepared using a nepionine resin.

Methods for producing a polymer electrolyte membrane using a commercially available nepheline resin and manufacturing a polymer electrolyte membrane using the nepion resin are known to those skilled in the art (see, for example, U.S. Patent No. 6,180,276) .

Direct methanol fuel cells use a polymer ion exchange membrane that transfers hydrogen ions to the electrolyte. The polymer electrolyte membrane acts as a separator for separating the fuel and oxygen from each other while acting as a carrier of hydrogen ions between the fuel electrode and the air electrode. Therefore, the polymer electrolyte membrane should have high hydrogen ion conductivity, low electron conductivity, less reactive gas or fuel transfer, and high mechanical and chemical stability.

Polymer electrolyte membranes, which are the most widely used electrolytes for direct methanol fuel cells, are nepionine non-crystalline polymers commercially available from DuPont, and linear polymers having a linear polymer chain. A structure in which a polymer main chain substituted by fluorine, which is a hydrophobic part, is separated into an ion phase which is a hydrophilic part, that is, a structure in which three phases of a crystal region of fluorocarbon, a hydrophilic ionic binder, and a definite hydrophobic region are present

In one embodiment of the present invention, a method for producing a polymer electrolyte membrane using a nepionic acid resin is a method in which a nepheionic resin is put into a molding frame or a rolling apparatus and heated at 200-250 [deg.] C in a hot- A membrane can be produced.

Next, a fine pattern is formed on the surface of the polymer electrolyte membrane.

In one embodiment of the present invention, the stamper for forming a fine pattern on the surface of the polymer electrolyte membrane may be patterned with a side length of 5 to 50 mu m, a gap of 5 to 50 mu m, and a height of 5 to 30 mu m Can be produced by using a photolithography method.

A polymer electrolyte membrane is placed between two stamper sheets as described above, and hot-pressed at 100-130 占 폚 to form a fine pattern on the surface of the polymer electrolyte membrane.

The above-mentioned stamp is prepared by forming a first stamp using polydimethylsiloxane (PDMS) and then forming a second stamp with PDMS to form a fine pattern on the surface of the polymer electrolyte membrane It can also be used as a stamp. As the first and second stamp materials, molding silicone elastomers other than PDMS, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polystyrene (PS), dibenzyl peroxide (BPO) have. It is also possible to fabricate a second stamp by electroplating after duplicating the surface with a cellulose film.

The temperature and pressure in the process of putting into the polymer electrolyte membrane between the spamper and hot-pressing can be appropriately controlled by those skilled in the art.

According to the above-described process, a fine pattern having a side length of 5 to 50 μm, an interval of 5 to 50 μm and a height of 5 to 30 μm is formed on the surface of the polymer electrolyte membrane, and a three-phase system in which an electrochemical reaction occurs is increased, The performance of the battery can be improved.

In another embodiment of the present invention, it is possible to use a sieve for screen printing having a fine mesh structure (shed) having a size of 5 to 50 μm instead of a stamp for forming a fine pattern on the surface of the polymer electrolyte membrane. In addition, fine patterns or network structures may be formed on circular rollers instead of stamps, and fine patterns may be formed on the upper and lower surfaces of the polymer membrane by a continuous process by passing the polymer electrolyte membrane through the rollers using a hot roller system composed of two pairs of upper and lower pairs .

Thereafter, a pretreatment process is performed to produce a membrane / electrode assembly using a polymer electrolyte membrane.

The patterned fluoride polymer membrane should be converted to H ⁺ form capable of conducting hydrogen ions.

In the present invention, the process of pretreating the polymer electrolyte membrane comprises treating the polymer electrolyte membrane in a mixed solution of caustic soda (NaOH) and methanol (CH ₃ OH) in a weight ratio of 5-30, washing with distilled water to remove impurities, 5 M sulfuric acid (H ₂ SO ₄ ) solution, treating with distilled water, and drying the polymer electrolyte membrane.

A membrane / electrode assembly is manufactured using the polymer electrolyte membrane and the gas diffusion layer for a fuel cell manufactured according to the above-described method.

In the present invention, a catalyst slurry can be coated on a plate of a high temperature by a brushing and spraying method using a CCM (Catalyst Coated Membrane) method, which is a method of directly coating the surface of a polymer electrolyte membrane, and a spray method is used on the surface of a polymer electrolyte membrane The effect of the generated pattern can be seen larger.

The catalyst slurry used in the present invention includes platinum catalyst, nepionine solution, ethanol, and distilled water. As the solvent of the catalyst slurry, ethanol or isopropyl alcohol having a low boiling point is used, and the plate temperature is set to about 100-120 ° C. As soon as the solvent such as water or alcohol contained in the slurry reaches the surface of the polymer electrolyte membrane If the catalyst layer is evaporated immediately, the surface of the membrane may be distorted to prevent the coated catalyst layer from cracking or falling.

The catalyst slurry is coated on the surface of the polymer electrolyte membrane and the polymer electrolyte membrane is hot-pressed to prepare a membrane / electrode assembly.

The present invention also provides a fuel cell manufactured using the membrane / electrode assembly.

If the amount of the platinum (Pt) catalyst required to obtain the same performance value is considered in the present invention, the performance of the fuel cell can be improved by about 10 to 30% by forming a pattern on the surface of the polymer electrolyte membrane. It can secure price competitiveness, which is the biggest obstacle to commercialization.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example

Manufacturing Example: Manufacturing of Stamper

A pattern forming stamper necessary for forming a pattern on the surface of a polymer membrane was manufactured by using a photolithography method capable of pattern processing. (A) 45 μm, 50 μm and 20 μm, (b) 30 μm, 45 μm and 25 μm, respectively, in the rectangular patterns. (C) 24 탆, 20 탆 and 20 탆, respectively. A schematic view of the stamper manufactured by the photolithography method is shown in Fig.

Example 1

(1) Production of a polymer electrolyte membrane

Perfluorosulfonyl fluoride / TFE copolymer resin (nepion resin) was prepared by hot-pressing or rolling at a temperature of 200-250 占 폚 to form a polymer electrolyte membrane having a thickness of about 100-130 占 퐉. 7 x 7 cm ² 1.26 g of nepionic acid resin was put into a molding frame and hot-pressed at a pressure of 8 MPa and a temperature of 200-250 ° C for 1 minute to prepare a polymer ion exchange membrane. In order to form a pattern on the surface of the polymer electrolyte membrane, (a) a polymer electrolyte membrane made of nepheionic resin was inserted between two stamper plates formed with fine patterns of 45 μm, 50 μm and 20 μm, Lt; / RTI > for 1 minute.

Then, the polymer electrolyte membrane was treated with a solution having a volume ratio of 20% caustic soda: methanol = 2: 1 (volume ratio) at 90 캜 for 7 hours. After washing with distilled water, 5% hydrogen peroxide And treated at 80 ° C for 1 hour. After treating with distilled water at 80 ° C for 1 hour, the polymer membrane was added to 0.1-5M sulfuric acid solution and treated at 80 ° C for 1 hour. It was then washed again with distilled water. Finally, moisture absorbed in the polymer membrane was removed so that the surface of the polymer membrane was not corroded by the water absorbed at the time of coating. In this process, the polymer membrane having the fine pattern formed thereon was placed between the porous carbon plates and dried in a vacuum oven at 60 DEG C for 24 hours.

(2) Preparation of membrane / electrode assembly

The effective electrode area was 9 cm ² (3 cm 3 cm), and the catalyst slurry was coated by a brushing method on a plate of 100-120 ° C by a CCM method of coating directly on the surface of the polymer membrane. In the coating process, when the solvent such as water or alcohol contained in the slurry contacts the surface of the polymer membrane, the film surface is distorted and the coated catalyst layer is cracked or dropped. Therefore, ethanol with low boiling point was selected as a solvent for the catalyst slurry and the plate temperature was set at 100-120 ° C. At this time, even if the temperature of the plate is high, the polymer is firmly fixed to the chalet after the solvent is contacted and the polymer membrane is distorted by the solvent until the solvent is completely evaporated. The process was fixed with a double-sided adhesive tape on the edge of the polymer membrane as shown below, and a small amount of ethanol was applied to the polymer membrane to securely fix the membrane using van der Waals force generated when the ethanol evaporated. The catalyst slurry consisted of catalyst, 10 wt% nepion solution (DuPont), ethanol, and distilled water. Johnson Matthey 12100 and 13100 were used as the anode and cathode, respectively, and the platinum catalyst loading was 2 mg Pt / cm ² . After coating, only the polymer electrolyte membrane was hot-pressed at a temperature of 150 ° C and a pressure of 3 MPa. Finally, a membrane / electrode assembly was fabricated using coated polymer membrane and gas diffusion layer. As the gas diffusion layer, water repellent treated anode and Toray 060 and SGL 25BC for air electrode were used, respectively.

(3) Production of direct methanol fuel cell

Using this membrane / electrode assembly, a direct methanol fuel cell was fabricated by using a Teflon gasket of 150 mu m and 180 mu m on the anode and the cathode, respectively.

Examples 2 to 3

(B) 30 μm, 45 μm and 25 μm, and (c) 24 μm, 20 μm and 20 μm, respectively.

Comparative Example 1

The procedure of Example 1 was repeated except that fine patterns of 45 탆, 50 탆 and 20 탆 in size were formed on a Nafion-115 membrane commercially available from DuPont as a polymer electrolyte membrane.

Comparative Example 2

The same procedure as in Example 1 was carried out using a polymer electrolyte membrane on which a surface of a Nafion-115 membrane commercially available from DuPont as a polymer electrolyte membrane was subjected to a sandpaper scratch.

Comparative Example 3

The procedure of Example 1 was repeated except that the polyelectrolyte membrane prepared from the perfluorosulfonyl fluoride / TFE copolymer resin (nepion resin) was used without surface treatment.

Test Example 1: Measurement of surface area of a polymer electrolyte membrane

(Fig. 5A) in which a fine pattern was formed in Comparative Example 1 (Fig. 5A), and the surface of the polymer electrolyte membrane (Fig. 5A to 5D) made of nepion resin in Examples 1 to 3 Was photographed by scanning electron microscope and is shown in Fig.

Referring to FIG. 5, when compared with a patterned flat membrane (Nafion-115 membrane) due to a fine pattern formed on the surface of a polymer electrolyte membrane using a stamper as in Examples 1 to 3, Of the polymer electrolyte membrane increased by 39.8%, 53.3% and 99.1%, respectively.

Test Example 2: Characterization of polymer electrolyte membrane for solvent

The performance of the polymer electrolyte membrane prepared in Example 1 and Comparative Example 1 after coating with the catalyst slurry was tested to test whether the pattern of the surface of the polymer electrolyte membrane was maintained.

Referring to FIG. 6, the pattern of the commercial polymer electrolyte membrane prepared in Comparative Example 1 was retained on one side while the pattern on the other side was lost. On the other hand, the pattern of the polymer electrolyte membrane made of the naphthol resin of Example 1 was both It was maintained.

The surface of the polyelectrolyte membrane prepared in Example 1 and Comparative Example 1 before and after the hydration treatment was photographed using a luminescence microscope and the plane and cross section of the pattern of the polymer electrolyte membrane of Example 1 are shown in Figs. (c), and the plan and cross-sectional views of the pattern of the polymer electrolyte membrane of Comparative Example 1 are shown in Figs. 7 (b) and 7 (d).

The patterns shown in FIGS. 7A and 7C have a length (length) of 45 μm and a height of 20 μm, respectively. However, the patterns shown in FIGS. 7B and 7D It was found that the length (length) and the height were 42 ㎛ and 10 ㎛, respectively, which were smaller than the original pattern size, and in particular, the height was lowered by 50% or more.

6 and 7, when a solvent such as water or alcohol is absorbed, a commercial Nepion membrane having a pattern formed by applying a mechanical force at a high temperature expands, and a recovery phenomenon to recover the original flat shape occurs It was difficult to maintain the original pattern size. That is, the formation of the pattern on the commercial NEPION membrane is temporarily formed by applying the pressure and the temperature. However, when the pattern is formed on the polymer electrolyte membrane made of the nepionic resin as in the present invention, Can be maintained.

Test Example 3: Performance comparison of direct methanol fuel cell

The performance (voltage, current density, power density) of the direct methanol fuel cell using the pattern size and surface area ratio of the polymer membrane prepared in Examples 1 to 3 and Comparative Example 3 was measured and shown in Table 1 and FIG.

Comparative Example 3 Example 1 Example 2 Example 3 Pattern size formed
(Width / interval / height) [占 퐉] none 45/50/20 30/45/25 24/20/20 Power density (0.4V) (mA / cm ² ) 219 225 240 260 Output Density (0.4V) (mW / cm ² ) 87 89 93 103 Maximum power density
(mW / cm ² ) 98 108 110 118 The surface area ratio (A _ge / A ₀ ) 1.0 1.39 1.53 1.99

Referring to Table 1 and FIG. 8, the performance of the direct methanol fuel cell manufactured in Comparative Example 3 using the nepheline resin-made polyelectrolyte membrane having no fine pattern was 219 mA / cm ² based on 0.4 V, The performance of the direct methanol fuel cell manufactured in Examples 1 to 3 using the formed polymer electrolyte membrane was 225 to 260 mA / cm ² . By forming a fine pattern on the polymer electrolyte membrane, the performance of the fuel cell was improved by 10 to 20%. The increase in the performance of the fuel cell using the polymer electrolyte membrane was analyzed by measuring the resistance using the AC impedance method.

FIG. 9 shows the results obtained by measuring the impedance of the direct methanol fuel cell prepared in Examples 1 to 3 and Comparative Example 3 at 1.35 A. FIG. Referring to FIG. 9, it can be seen that the ohmic resistance value at the point where the graph meets the x-axis is 0, as the surface area increases. This is because the surface area of the polymer electrolyte membrane in contact with the catalyst is increased (up to 99% increase) by putting the pattern on the surface of the polymer electrolyte membrane. That is, it is judged that the three-phase system is increased. Also, as the surface area increases, the polarization resistance value decreases. It is considered that the surface area is increased and the performance is increased due to more electrochemical reaction.

Referring to FIG. 10, in the direct methanol fuel cell using the polymer electrolyte membrane in which the fine patterns are formed in Examples 1 to 3, the current and the output density are increased when the surface area is increased. When the surface area is increased by about 99% The density is increased by 20%, and the output density is increased by 22%.

Claims (14)

Preparing a polymer electrolyte membrane using a perfluorosulfonyl fluoride / TFE copolymer resin;
Forming a fine pattern on a surface of the polymer electrolyte membrane using a stamper, a screen printer network, or a hot roller system; And
Pre-treating the polymer electrolyte membrane;
Wherein the polymer electrolyte membrane of the fuel cell comprises a polymer electrolyte membrane.
The method according to claim 1,
Wherein the fine pattern formed on the surface of the polymer electrolyte membrane has a side length of 5 to 50 탆, an interval of 5 to 50 탆, and a height of 5 to 30 탆.
The method according to claim 1,
Wherein the fine pattern on the surface of the polymer electrolyte membrane is formed using a net for screen printing having a fine mesh structure having a size of 5 to 50 占 퐉.
The method according to claim 1,
The fine pattern on the surface of the polymer electrolyte membrane is formed by passing a polymer electrolyte membrane between rollers using a hot roller system having fine patterns on the surface of two pairs of upper and lower circular rollers to form fine patterns on the upper and lower surfaces of the polymer electrolyte membrane in a continuous process Wherein the polymer electrolyte membrane of the fuel cell is produced by the method.
The method according to claim 1,
Wherein the stamp comprises a material selected from the group consisting of polydimethylsiloxane (PDMS), silicone elastomer, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polystyrene (PS), dibenzyl peroxide (BPO) Wherein the polymer electrolyte membrane is formed on the surface of the polymer electrolyte membrane.
The method according to claim 1,
The process of pretreating the polymer electrolyte membrane comprises treating the polymer electrolyte membrane in a mixed solution of caustic soda and methanol at a weight ratio of 5-30, washing with distilled water and removing impurities, treating the polymer electrolyte membrane with 0.1-5 M sulfuric acid solution and treating with distilled water And drying the polymer electrolyte membrane. The method of manufacturing a polymer electrolyte membrane of a fuel cell according to claim 1,
The method according to claim 1,
Wherein the polymer electrolyte membrane is a polymer electrolyte membrane for a direct methanol fuel cell that transfers hydrogen ions.
A polymer electrolyte membrane for a fuel cell produced according to any one of claims 1 to 7.
A method for manufacturing a membrane / electrode assembly for a fuel cell, comprising: coating a surface of a polymer electrolyte membrane according to claim 8 with a catalyst slurry.
10. The method of claim 9,
Wherein the catalyst slurry comprises a platinum catalyst, a nepion solution, ethanol, and distilled water.
10. The method of claim 9,
Wherein the catalyst slurry is coated on the surface of the polymer electrolyte membrane and the polymer electrolyte membrane is hot-pressed.
11. A membrane / electrode assembly for a fuel cell produced according to any one of claims 9 to 11.
13. A fuel cell comprising the membrane / electrode assembly for a fuel cell according to claim 12.
14. The method of claim 13,
Wherein the direct methanol fuel cell is a direct methanol fuel cell.

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