KR20160011487A - Membrane electrode assembly and fuel cell including the same - Google Patents

Abstract

Disclosed are a membrane electrode conjugate and a fuel cell comprising the membrane electrode conjugate. The membrane electrode conjugate comprises: a cathode; an anode; and an electrolyte membrane interposed between the cathode and the anode, wherein each of the cathode and the anode comprises: a catalyst layer which comes in contact with the electrolyte membrane; a hydrophilic micro-pore layer which comes in contact with the catalyst layer; and a gas diffusing layer which comes in contact with the micro-pore layer.

Description

[0001] Membrane Electrode Assembly and Fuel Cell Including the Membrane Electrode [0002]

Membrane electrode assembly and a fuel cell including the membrane electrode assembly.

BACKGROUND ART A fuel cell is a power generation device that converts chemical energy of hydrogen and oxygen in the air directly to electric energy, which can be obtained from a hydrocarbon-based material such as natural gas, methanol, and ethanol, and has high efficiency and high energy density. Such a fuel cell is a clean energy source that can replace fossil energy, has various operating temperatures depending on the selection of electrolyte, and has an advantage of outputting a wide range of output by stacking stacked unit cells. Therefore, fuel cells are attracting attention as energy sources that can be applied in various applications ranging from compact and mobile power sources to large-scale power generation.

Representative examples of the fuel cell include a polymer electrolyte fuel cell (PEMFC) and a direct methanol fuel cell (DMFC). The fuel cell uses a polymer membrane capable of conducting hydrogen ion conductivity as an electrolyte.

In particular, polymer electrolyte fuel cells can be applied to various fields ranging from mobile electronic devices, portable power sources, small cogeneration, and automobiles. A polymer electrolyte fuel cell typically comprises a membrane-electrode assembly (MEA) including a cathode, an anode, and a polymer electrolyte membrane disposed therebetween, and a plate including a flow path for supplying fuel and air. In the anode, protons are generated through hydrogen oxidation reaction, and the generated protons pass through the polymer electrolyte membrane and move to the cathode. At the cathode, water is produced through an oxygen reduction reaction.

In a low-temperature polyelectrolyte fuel cell operating at a temperature of 90 ° C or less, if water produced through the oxygen reduction reaction is not discharged, water floods and flooding occurs which interferes with fuel supply. Therefore, in order to prevent such flooding, a hydrophobic compound such as a fluorine-based compound is added to facilitate the discharge of the generated water so that the microporous layer and / or the gas diffusion layer of the electrode have water repellency.

On the other hand, a high-temperature polyelectrolyte fuel cell operating at a temperature of 90 ° C or higher can obtain a high output, but the water easily evaporates in the above-mentioned temperature range, and the proton conductivity of the ionomer and the membrane is lowered. Therefore, there is a demand for a membrane electrode assembly which provides high output at high temperature and low humidity (for example, 120 DEG C, relative humidity of 40% or less).

One aspect is to provide a membrane electrode assembly comprising a hydrophilic microporous layer.

And another aspect thereof is to provide a fuel cell including the membrane electrode assembly.

On one side

Cathode; Anode; And an electrolyte membrane sandwiched therebetween,

The cathode and the anode are

A catalyst layer in contact with the electrolyte membrane;

A hydrophilic microporous layer in contact with the catalyst layer; And

There is provided a membrane electrode assembly including a gas diffusion layer in contact with the microporous layer.

According to another aspect, there is provided a fuel cell including the membrane electrode assembly.

By including the hydrophilic microporous layer, it is possible to provide a fuel cell having improved capability of membrane electrode assembly and excellent performance even at high temperature and low relative humidity.

1 is an exploded perspective view showing a structure of a fuel cell according to one embodiment.
2 is a cross-sectional schematic diagram of a membrane electrode assembly (MEA) according to one embodiment.
FIG. 3 is a graph showing AC impedance of the unit cells manufactured in Examples 1 and 5 and Comparative Example 2. FIG.
FIG. 4 is a graph showing the cell voltage versus current density of the unit cells of Examples 1, 2 and 5 and Comparative Examples 1 and 2. FIG.
FIG. 5 is a graph showing the cell voltage versus current density of the unit cells of Examples 3 to 6. FIG.

Hereinafter, the membrane electrode assembly according to exemplary embodiments and the fuel cell including the membrane electrode assembly will be described in more detail.

As used herein, "low relative humidity " means a relative humidity in the range of greater than 0% to less than about 80%.

As used herein, the term " hydrophilic " refers to a property opposite to "hydrophobic ", which has a high affinity for moisture and can contain moisture.

A cathode according to one aspect; Anode; And an electrolyte membrane sandwiched therebetween, wherein the cathode and the anode each are in contact with the electrolyte membrane; A hydrophilic microporous layer in contact with the catalyst layer; And a gas diffusion layer in contact with the microporous layer.

Since the cathode and the anode simultaneously include the hydrophilic microporous layer in the membrane electrode assembly according to one embodiment, the moisture content in the membrane electrode assembly can be kept high even at a high temperature of 90 ° C or higher and a relative humidity of 80% or less, Can be prevented from being lowered. As a result, the output characteristics of the high temperature polyelectrolyte fuel cell can be improved by employing the membrane electrode assembly in which the cathode and the anode simultaneously include the hydrophilic microporous layer.

The thickness of the hydrophilic microporous layer in the membrane electrode assembly according to one embodiment may be 1 탆 or more. For example, the thickness of the hydrophilic microporous layer may be between 1 탆 and 100 탆. For example, the thickness of the hydrophilic microporous layer may be between 10 μm and 100 μm. For example, the thickness of the hydrophilic microporous layer may be 20 [mu] m to 60 [mu] m. If the thickness of the hydrophilic microporous layer is less than 1 mu m, it may be difficult to maintain the moisture content inside the membrane electrode assembly at a high level. If the thickness of the hydrophilic microporous layer is more than 100 mu m, fuel may be difficult to permeate through the microporous layer, and fuel supply may be difficult.

In a membrane electrode assembly according to one embodiment, the hydrophilic microporous layer may comprise a porous material and a hydrophilic coating layer introduced onto the porous material. That is, the hydrophilic microporous layer may have a core / shell structure composed of a core containing a porous material and a hydrophilic coating layer formed on the core. The hydrophilic coating layer may be introduced into part or all of the surface of the porous material.

The specific surface area of the porous material in the membrane electrode assembly according to one embodiment may be 50 m ² / g or more. For example, the specific surface area of the porous material may be 200 m ² / g or more. For example, the specific surface area of the porous material may be 50 to 2000 m ² / g. For example, the specific surface area of the porous material may be 50 to 1000 m ² / g. For example, the specific surface area of the porous material may be 200 to 1000 m ² / g. If the specific surface area of the porous material is less than 50 m ² / g, even if a hydrophilic coating layer is introduced on the porous material, the effect of improving the output by the hydrophilic microporous layer may be insignificant.

The average particle diameter of the porous material in the membrane electrode assembly according to one embodiment may be 20 nm or more. For example, the average particle size of the porous material may be 100 nm or more. For example, the average particle size of the porous material may be 20 nm or more. For example, the average particle diameter of the porous material may be 20 nm to 10 탆. For example, the average particle size of the porous material may be 100 nm to 10 탆. If the average particle diameter of the porous material is 20 nm or less, the water content in the microporous layer may be lowered due to the water being easily discharged through the void space between the porous materials.

The content of the porous material in the microporous layer of the membrane electrode assembly according to one embodiment may be 0.2 to 4 mg / cm ² . For example, the content of the porous material in the microporous layer may be 1 to 4 mg / cm ² . For example, the content of the porous material in the microporous layer may be 1 to 3 mg / cm ² . If the content of the porous material in the microporous layer is less than 0.2 mg / cm ^2, the thickness of the microporous layer becomes too thin, and it may be difficult to maintain the moisture content inside the membrane electrode assembly at a high level. If the content of the porous material in the microporous layer is more than 4 mg / cm ^2, the thickness of the hydrophilic microporous layer may become excessively thick and the fuel may be difficult to permeate the microporous layer.

In one embodiment, the porous material in the microporous layer of the membrane electrode assembly may be a carbonaceous material. Since the porous material is a carbon-based material, the microporous layer can have a high conductivity. For example, the porous material may include, but is not necessarily limited to, at least one selected from mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanowire, activated carbon, carbon black, and graphite Any conductive carbon-based material that can be used as a porous material of a fuel cell in the related art is available.

20 to 80% of the pores of the microporous layer in the microporous layer may have a pore size of 20 to 500 nm. By having the pore size of the microporous layer within the above range, a high moisture content and a good fuel passage can be realized at the same time.

The hydrophilic coating layer in the microporous layer of the membrane electrode assembly according to an embodiment may include a hydrophilic functional group. The hydrophilic coating layer may have the ability to absorb and retain moisture by including a hydrophilic functional group. For example, the hydrophilic functional group may include at least one selected from a carboxyl group, an ether group, a hydroxyl group, a phosphonium group, a sulfone group, an amine group, a pyridine group, an amide group and an acrylic group, Anything that can be used as a hydrophilic functional group in the technical field is possible.

In one embodiment, the hydrophilic coating layer of the microporous layer in the membrane electrode assembly may comprise a covalently bonded hydrophilic functional group on the porous material. For example, a hydrophilic functional group such as a hydroxy group may be directly covalently bonded to the porous material through an acid treatment or a plasma treatment to form a hydrophilic coating layer.

The hydrophilic coating layer of the microporous layer in the membrane electrode assembly according to one embodiment may include a hydrophilic polymer. For example, the hydrophilic polymer may be coated on the porous material to form a hydrophilic coating layer. For example, the hydrophilic polymer may be selected from the group consisting of polyvinyl alcohol (PVA), polyvinylpyridine (PVP), polyacrylic acid (PAA), polyacrylamide, polyallylamine, but not limited to, polyethyleneimine, polyalkyloxazoline, and polyalkylamine. Any material can be used as long as it can be used as a hydrophilic polymer in the related art. For example, the hydrophilic polymer is applied only to the microporous layer and is not applied to the catalyst layer, so that the catalytic activity of the catalyst layer may not be lowered.

The amount of the hydrophilic coating layer in the membrane electrode assembly according to one embodiment may be 1 to 10% by weight of the total weight of the microporous layer. If the content of the hydrophilic coating layer is less than 1% by weight, it may be difficult to maintain the moisture content inside the membrane electrode assembly at a high level. If the content of the hydrophilic coating layer is more than 10% by weight, the thickness of the hydrophilic coating layer becomes too thick and the fuel may be difficult to permeate through the microporous layer.

The catalyst layer of each of the cathode and the anode in the membrane electrode assembly may comprise a catalyst material and a binder resin.

The catalytic material may comprise a carrier and a catalytic metal supported thereon. The carrier may be a carbon carrier such as carbon powder, carbon black, acetylene black, Ketjenblack, activated carbon, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nanohorn, carbon airgel, And may include two or more of these. The carbon-based carrier may have an average diameter in the range of, for example, 20 nm to 50 nm.

In a membrane electrode assembly according to an embodiment, a catalyst layer may include a catalyst metal supported on a carbonaceous carrier. For example, the catalytic metal may be selected from the group consisting of platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), platinum (Pt) V, Cr, Mo, W, Mn, Fe, Co, Rh) alloy, platinum (Pt) - iridium (Ir) alloy, platinum (Pt) - osmium alloy, platinum , Ni, Cu, Ag, Au, Zn, Ga, and Sn), or a combination thereof. However, the present invention is not limited thereto. The catalyst metal may be nanoparticles having an average particle diameter of 10 nm or less. If the particle size is larger than 10 nm, the surface area of the particles may be too small and the activity may be lowered. For example, the average particle size of the catalytic metal particles may be between 2 nm and 10 nm or between 3 nm and 8 nm.

For example, the catalyst material may be a platinum-based catalyst supported on a carbon-based support. For example, the catalyst material may be an alloy of platinum and cobalt (PtCo / C) supported on a carbon powder.

For example, the loading amount of the catalyst metal in the anode catalyst layer may be 0.1 to 2.0 mg / cm ² , and the loading amount of the catalyst metal in the cathode catalyst layer may be 0.1 to 2.0 mg / cm ² .

For example, the content of the catalyst metal in each of the anode and the cathode in the catalyst layer is 10 to 90 parts by weight, for example, 20 to 80 parts by weight, more preferably 30 to 30 parts by weight based on 100 parts by weight of the total weight of the catalyst metal and the support, To 60 parts by weight.

The binder resin may be a hydrogen ion conductive polymer resin. Representative examples of the hydrogen-ion conductive polymer resin include fluoro-based polymers, benzimidazole-based polymers, polyimide-based polymers, polyetherimide-based polymers, polyphenylene sulfide-based polymers, polysulfone-based polymers, polyether sulfone- Ether ketone-based polymers, polyether-ether ketone-based polymers, polyphenylquinoxaline-based polymers, or copolymers thereof. Specifically, the proton conductive polymer resin may be at least one selected from the group consisting of poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, Ketone, aryl ketone, poly (2,2'-m-phenylene) -5,5'-bibenzimidazole, poly (2,5-benzimidazole), or copolymers thereof, but is not limited thereto and can be used as long as it can be used as a hydrogen ion conductive polymer in the related art.

For example, the catalyst layer may have a volume of pores of 20-100 nm in size of 0.03-0.06 mL / g.

For example, the thickness of the catalyst layer may be 1 탆 to 100 탆 so that the electrode reaction is effectively activated and the electrical resistance is not excessively increased. For example, the thickness of the catalyst layer may be between 5 탆 and 80 탆. For example, the thickness of the catalyst layer may be 10 [mu] m to 60 [mu] m.

The electrolyte membrane in the membrane electrode assembly may comprise an ion conductive polymer. The hydrogen ions (H ⁺ ) generated by ionization of the fuel in the catalyst layer of the anode pass through the electrolyte membrane and are transferred to the catalyst layer of the cathode.

The electrolyte membrane in the membrane electrode assembly according to one embodiment is not particularly limited, but may be, for example, poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), tetrafluoroethylene containing sulfonic acid group, Vinyl ether copolymers, defluorinated sulfated polyether ketones, aryl ketones, poly (2,2'-m-phenylene) -5,5'-bibenzimidazole (Poly (2,2 '- phenylene) -5,5'-bibenzimidazole, poly (2,5-benzimidazole), and copolymers thereof.

Since the polymer electrolyte has a hydrophilic group such as a sulfonic acid group, a hydrophilic region is formed by this hydrophilic group. In this hydrophilic region, the attractive force between the hydrogen ion and the sulfonic acid group is relatively weak, so that the hydrogen ion can move freely with the water.

According to another aspect, there is provided a fuel cell including the membrane electrode assembly described above.

The fuel cell according to one embodiment may be a polymer electrolyte fuel cell (PEMFC).

1 is an exploded perspective view showing an embodiment of a fuel cell. Referring to FIG. 1, the fuel cell 100 has two unit cells 11 sandwiched between a pair of holders 12. The unit cell 11 is composed of a membrane electrode assembly 10 and a bipolar plate 20 disposed on both sides in the thickness direction of the membrane electrode assembly 10. The bipolar plate 20 may be made of a conductive metal, carbon, or the like. The bipolar plate 20 functions as a current collector by joining to the membrane electrode assembly 10 and includes a channel so that fuel and oxygen can be supplied to the catalyst layer of the membrane electrode assembly 10.

Although two unit cells 11 are shown in the fuel cell 100 of FIG. 1, the number of unit cells is not limited to two, and may be increased to several tens to several hundreds depending on characteristics required for a fuel cell.

2 is a cross-sectional schematic diagram of a membrane electrode assembly (MEA) according to one embodiment of the fuel cell of FIG.

2, the membrane electrode assembly 10 includes an electrolyte membrane 1, a catalyst layer 5 disposed on both sides in the thickness direction of the electrolyte membrane 1, a hydrophilic microporous layer 8 on the catalyst layer 5, And a gas diffusion layer 9. The catalyst layer 5 on one side, the hydrophilic microporous layer 8 and the gas diffusion layer 9 constitute the anode and the catalyst layer 5 on the other side, the hydrophilic microporous layer 8 and the gas diffusion layer 9 Thereby constituting the cathode.

Proton (hydrogen ion) generated by oxidation of fuel in a fuel cell moves from the anode electrode to the cathode electrode. At this time, the proton (hydrogen ion) forms ions together with water and moves. Therefore, a sufficient amount of water must be present in the electrolyte membrane of the fuel cell and the inside of the electrode to smoothly perform the reaction. Therefore, the fuel cell generally operates in a high humidity environment close to 100%. However, in a high-temperature polyelectrolyte fuel cell operating at a driving temperature of 90 ° C or higher, water evaporates easily and it is difficult to realize a high-humidity environment close to 100%.

The hydrophilic microporous layer 8 is introduced between the catalyst layer 5 and the gas diffusion layer 9 in the fuel cell according to an embodiment of the present invention to improve the moisture content of the membrane electrode assembly so that proton (hydrogen ion) migration .

The fuel cell according to one embodiment may be driven at a driving temperature of, for example, 90-250 DEG C, and a relative humidity of 0-80%. For example, the fuel cell can be operated at a driving temperature of 90 to 120 DEG C and a relative humidity of 20 to 40%.

The structure and the manufacturing method of the fuel cell are not particularly limited, and specific examples thereof are well known in various documents and therefore will not be described in detail here.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited thereto.

Example 1

(a) Preparation of Catalyst Coated Membrane (CCM)

The weight ratio of the Pt-supported carbon catalyst (Pt / C) (Tanaka) to the ionomer (Aquivion ™ R79-20BS (equivalent weight 790 g / mol SO ₃ H, (Pt / C: ionomer) was printed on a PTFE (polytetrafluoroethylene) sheet to form a catalyst layer on two PTFEs. The catalyst layers on the two PTFEs were transferred to both sides of an electrolyte membrane (Aquivion ™ R79-02S) (molar equivalent 790 g / mol SO ₃ H) having a thickness of 20 μm to form a catalyst coating layer consisting of a catalyst layer / electrolyte membrane / catalyst layer. At this time, the content of Pt in each catalyst layer was 0.4 mg / cm ² , the area of the catalyst layer was 10 cm ² , and the thickness of the catalyst layer was 15 탆.

(b) Formation of a hydrophilic microporous layer

Microporous layer slurry containing acetylene black (specific surface area 70 m ² / g, average particle diameter 30 nm) and 5 wt% polyvinyl alcohol (PVA) binder was applied onto two gas diffusion layers (Toray 060-plain) mg / cm < ² > and a thickness of 50 [mu] m.

(c) Production of membrane electrode assembly and unit cell

An electrolyte membrane having a catalytic layer bonded on both sides thereof is inserted between a gas diffusion layer coated with a hydrophilic microporous layer and a gasket and then inserted between two carbon plates having a gas flow channel of a certain shape to form a membrane electrode assembly . Then, this was tightened using a SUS end plate to produce a unit cell.

Example 2

The same procedure as in Example 1 was carried out except that a microporous layer having a content of 2.2 mg / cm ² and a thickness of 50 탆 was formed using Vulcan (VULCAN XC72R, specific surface area 250 m ² / g, average particle diameter 30 nm) To prepare a membrane electrode assembly and a unit cell.

Example 3

Using a microporous layer slurry containing ordered mesoporous carbon (specific surface area 700 m ² / g, average particle diameter 100 nm) and 1 wt% polyvinyl alcohol (PVA) binder, 2.6 mg / cm 2 ² , and a microporous layer having a thickness of 50 탆 was formed on the surface of the membrane electrode assembly.

Example 4

Using a microporous layer slurry containing ordered mesoporous carbon (specific surface area 700 m ² / g, average particle diameter 100 nm) and 3 wt% polyvinyl alcohol (PVA) binder, 2.6 mg / cm 2 ² , and a microporous layer having a thickness of 50 탆 was formed on the surface of the membrane electrode assembly.

Example 5

Using a microporous layer slurry containing ordered mesoporous carbon (specific surface area 700 m ² / g, average particle diameter 100 nm) and 5 wt% polyvinyl alcohol (PVA) binder, 2.6 mg / cm 2 ² , and a microporous layer having a thickness of 50 탆 was formed on the surface of the membrane electrode assembly.

Example 6

Using a microporous layer slurry containing ordered mesoporous carbon (specific surface area 700 m ² / g, average particle diameter 100 nm) and 10 wt% polyvinyl alcohol (PVA) binder, 2.6 mg / cm 2 ² , and a microporous layer having a thickness of 50 탆 was formed on the surface of the membrane electrode assembly.

Comparative Example 1

A membrane electrode assembly and a unit cell were produced in the same manner as in Example 1, except that the moisturizing layer was not used.

Comparative Example 2

Using a microporous layer slurry containing acetylene black (specific surface area 70 m ² / g, average particle diameter 30 nm) and 30 wt% polytetrafluoroethylene (PTFE) binder, 2.0 mg / cm ² And a microporous layer having a thickness of 50 탆 was formed on the surface of the membrane electrode assembly and the unit cell.

Evaluation example 1: Impedance measurement

The membrane electrode assembly manufactured in Examples 1 to 6 and Comparative Examples 1 and 2 was measured for resistance of the membrane electrode assembly by a 2-probe method using an impedance analyzer (Solartron 1260A Impedance / Gain-Phase Analyzer) Respectively. The current density was 0.4 A / cm < ² > and the frequency range was 0.1 Hz to 10 KHz. Nyguist plots of impedance measurements of the unit cells of Examples 1 and 5 and Comparative Example 2 are shown in FIG. In Fig. 3, the impedance of the membrane electrode assembly is determined by the position and size of the semicircle. The first x-axis (ie, abscissa) section of the semicircle represents the resistance (R _ohm ) of the electrolyte membrane and the difference between the first x-axis section and the second x-axis section of the semicircle represents the charge transfer resistance (R _ct , (W, Warburg element) due to cathode charge transport resistance and mass transfer of fuel.

The results of analyzing the graph of FIG. 3 are shown in Table 1 below.

Electrolyte membrane resistance (R _ohm )
[ohm ㅇ cm ² ] The electrolyte membrane resistance (R _ct )
[ohm ㅇ cm ² ] Example 1 0.257 0.594 Example 5 0.201 0.538 Comparative Example 2 0.271 0.620

As shown in Table 1, the electrolyte membrane resistance and the electrode resistance of the membrane electrode assembly of Examples 1 and 5 were lower than those of the membrane electrode assembly of Comparative Example 2, respectively. This decrease in resistance is believed to be due to the increase in the water content in the electrode due to the introduction of the hydrophilic microporous layer in the membrane electrode assembly of the embodiment, resulting in a decrease in the charge transfer resistance and the migration resistance of hydrogen ions.

Evaluation Example 2: Evaluation of output density (change of carbon-based material type)

The unit cells prepared in Examples 1, 2 and 5 and Comparative Examples 1 and 2 were supplied with hydrogen at the anode electrode side and air at the cathode electrode side, respectively, and the output density at a temperature of 120 ° C. and a relative humidity of 40% power density) were measured. At this time, the relative pressure was 0 bar, the hydrogen flow rate was 52 sccm, and the air flow rate was 200 sccm. The results are shown in Fig. 4 and Table 2 below.

Voltage at a current density of 0.2A / cm ² [V] Voltage at a current density of 0.4A / cm ² [V] Example 1 0.636 0.508 Example 2 0.660 0.516 Example 5 0.682 0.525 Comparative Example 1 0.628 0.490 Comparative Example 2 0.626 0.489

As shown in Table 2, the unit cells of Examples 1, 2, and 5 had higher output densities than the unit cells of Comparative Examples 1 and 2. The improvement of the output density is considered to be due to the increase of the water content in the electrode and the membrane due to the introduction of the hydrophilic microporous layer and the reduction of the charge transfer resistance and the hydrogen ion migration resistance.

In addition, the unit cell of Example 5 had an improved output density as compared with the unit cells of Examples 1 and 2. It is considered that the improvement of the output density is attributable to the increase of the hydrophilic specific surface area which can improve the moisture retention due to the increase of the specific surface area of the porous carbonaceous material of the hydrophilic microporous layer.

Evaluation Example 3: Evaluation of power density (change in hydrophilic polymer content)

The unit cells prepared in Examples 3 to 6 and Comparative Examples 1 and 2 were supplied with hydrogen at the anode electrode side and air at the cathode electrode side respectively and then the power density at a temperature of 120 ° C and a relative humidity of 40% ) Were measured. At this time, the relative pressure was 0 bar, the hydrogen flow rate was 52 sccm, and the air flow rate was 200 sccm. The results are shown in Fig. 5 and Table 3 below.

Voltage at a current density of 0.4A / cm ² [V] Example 3 0.462 Example 4 0.489 Example 5 0.525 Example 6 0.473

As shown in Table 3, the unit cells of Examples 4 to 5 had relatively higher output densities than the unit cells of Examples 3 and 6.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Accordingly, the scope of protection of the present invention should be determined by the appended claims.

1: electrolyte membrane 2: catalyst metal
3: Carrier 4: Binder (ionomer)
5: catalyst layer 6: porous material
7: hydrophilic coating layer 8: hydrophilic microporous layer
9: diffusion layer 10: membrane electrode assembly
11: unit cell 12: end plate
20: bipolar plate 100: fuel cell

Claims (20)

Cathode; Anode; And an electrolyte membrane sandwiched therebetween,
The cathode and the anode are
A catalyst layer in contact with the electrolyte membrane;
A hydrophilic microporous layer in contact with the catalyst layer; And
And a gas diffusion layer contacting the microporous layer. The membrane electrode assembly according to claim 1, wherein the hydrophilic microporous layer has a thickness of 1 占 퐉 or more. The membrane electrode assembly of claim 1, wherein the hydrophilic microporous layer comprises a porous material and a hydrophilic coating layer introduced on the porous material. The membrane electrode assembly according to claim 3, wherein the porous material has a specific surface area of 50 m ² / g or more. The membrane electrode assembly according to claim 3, wherein the specific surface area of the porous material is 200 m ² / g or more. The membrane electrode assembly according to claim 3, wherein the porous material has an average particle diameter of 20 nm or more. The membrane electrode assembly according to claim 3, wherein the porous material has an average particle diameter of 100 nm or more. The membrane electrode assembly according to claim 3, wherein the content of the porous material is 0.2 to 4 mg / cm ² . The membrane electrode assembly according to claim 3, wherein the porous material is a carbon-based material. The membrane electrode assembly according to claim 3, wherein the porous material comprises at least one selected from the group consisting of mesoporous carbon, carbon nanotube, carbon nanofiber, activated carbon carbon nanowire, activated carbon, carbon black, and graphite. The membrane electrode assembly according to claim 3, wherein 20 to 80% of the pores of the porous material have a pore size of 20 to 500 nm. The membrane electrode assembly according to claim 3, wherein the hydrophilic coating layer comprises a hydrophilic functional group. The membrane electrode assembly according to claim 12, wherein the hydrophilic functional group comprises at least one selected from a carboxyl group, an ether group, a hydroxyl group, a phosphonium group, a sulfone group, an amine group, a pyridine group, an amide group and an acrylic group. The membrane electrode assembly of claim 3, wherein the porous coating layer comprises a hydrophilic polymer. The method of claim 14, wherein the hydrophilic polymer is selected from the group consisting of polyvinyl alcohol (PVA), polyvinylpyridine (PVP), polyacrylic acid (PAA), polyacrylamide, polyallylamine, Wherein the membrane electrode assembly comprises at least one selected from the group consisting of polyethyleneimine, polyalkyloxazoline, and polyalkylamine. The membrane electrode assembly according to claim 3, wherein the content of the hydrophilic coating layer is 1 to 10% by weight of the total weight of the microporous layer. The membrane electrode assembly according to claim 1, wherein the catalyst layer comprises a catalyst metal supported on a carbon-based support. The method of claim 1, wherein the catalyst metal is at least one selected from the group consisting of Pt, Fe, Co, Ni, Ru, Rh, Pd, Os, A membrane electrode assembly comprising at least one selected from the group consisting of iridium (Ir), copper (Cu), silver (Ag), gold (Au), tin (Sn), titanium (Ti), chromium (Cr) . The electrolyte membrane according to claim 1, wherein the electrolyte membrane is selected from the group consisting of poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), copolymer of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid group, Ketone, aryl ketone, poly (2,2'-m-phenylene) -5,5'-bibenzimidazole, poly (2,5-benzimidazole), and a copolymer thereof. A fuel cell comprising a membrane electrode assembly according to any one of claims 1 to 19.

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