KR102518521B1 - Complex electrolyte membrane for PEMFC containing the same, and Polymer electrolyte membrane fuel cell containing the same - Google Patents

Abstract

The present invention relates to a high durability improver for PEMFC, a composite electrolyte membrane for PEMFC, and a membrane-electrode assembly manufactured using the same, and specifically, to a composite electrolyte membrane for PEMFC and a membrane-electrode assembly, wherein when thinning a PEMFC electrolyte membrane, the durability of an electrolyte membrane decreases due to deterioration, but the high durability improver of the present invention suppresses the deterioration of the electrolyte membrane, thereby preventing a decrease in durability of the electrolyte membrane due to deterioration, and providing high dimensional stability, mechanical properties, and electrical stability.

Description

Membrane-electrode assembly for PEMFC and polymer electrolyte fuel cell containing the same {Complex electrolyte membrane for PEMFC containing the same, and Polymer electrolyte membrane fuel cell containing the same}

The present invention applies a high durability improver that suppresses chemical degradation of the electrolyte membrane of a membrane-electrode assembly (MEA) for PEMFC, and optimizes the platinum (Pt) content gradient in the anode electrode, electrolyte membrane, and cathode electrode of the MEA. Therefore, it relates to a membrane-electrode assembly for a polymer electrolyte membrane fuel cell (PEMFC) with improved electrochemical performance and long-term life stability and a PEMFC to which the same is applied.

A fuel cell is a power generation system that directly converts chemical energy generated by an electrochemical reaction between a fuel (hydrogen or methanol) and an oxidizing agent (oxygen) into electrical energy. research is being developed. Fuel cells can be used by selecting and using high-temperature and low-temperature fuel cells depending on the application field, and are generally classified according to the type of electrolyte. There is a fuel cell (Molten Carbonate Fuel Cell, MCFC) and the like, and an Alkaline Fuel Cell (AFC) and a Polymer Electrolyte Membrane Fuel Cell (PEMFC) are being developed for low-temperature applications.

미만의 낮은 작동온도, 고체 전해질 사용으로 인한 누수문제 배제, 빠른 시동과 응답 특성, 및 우수한 내구성 등의 장점으로 휴대용, 차량용, 및 가정용 전원장치로 각광을 받고 있다. 특히 다른 형태의 연료전지에 비하여 전류밀도가 큰 고출력 연료전지로서, 소형화가 가능하기 때문에 휴대용 연료전지로의 연구가 계속 진행되고 있다.The double polymer electrolyte fuel cell is divided into a Proton Exchange Membrane Fuel Cell (PEMFC) that uses hydrogen gas as fuel and direct methanol that uses liquid methanol directly supplied to the anode as fuel. There is a fuel cell (Direct Methanol Fuel Cell, DMFC). Polymer electrolyte fuel cells are 100

It is in the limelight as a portable, vehicle, and home power supply with advantages such as a low operating temperature of less than 100 degrees, elimination of leakage problems due to the use of solid electrolyte, fast start-up and response characteristics, and excellent durability. In particular, as a high-output fuel cell with a high current density compared to other types of fuel cells, research into portable fuel cells continues to be conducted because it can be miniaturized.

The unit cell structure of such a fuel cell has a structure in which an anode (fuel electrode) and a cathode (oxygen electrode) are coated on both sides of an electrolyte membrane composed of a polymer material, which is called a membrane-electrode assembly. Electrode Assembly, MEA). The membrane-electrode assembly (MEA) is a part in which an electrochemical reaction between hydrogen and oxygen occurs, and is composed of a cathode, an anode, and an electrolyte membrane, that is, an ion conductive electrolyte membrane (eg, a hydrogen ion conductive electrolyte membrane).

At the anode, hydrogen or methanol, which is a fuel, is supplied and an oxidation reaction of hydrogen occurs to generate hydrogen ions and electrons. .

This membrane-electrode assembly has a form in which the electrode catalyst layers of the anode and cathode are coated on both sides of the ion conductive electrolyte membrane, and the material constituting the electrode catalyst layer is Pt (platinum) or Pt-Ru (platinum-ruthenium). It is a form in which the catalyst material of is supported on a carbon carrier. Membrane-electrode assembly (MEA), which can be seen as a key part of the electrochemical reaction of fuel cells, uses an ion conductive electrolyte membrane and platinum catalyst, which have a high cost ratio, and is directly related to power production efficiency, so fuel cells It is considered as the most important part to improve the performance and price competitiveness of

A conventional method for manufacturing a commonly used MEA is to prepare a paste by mixing a catalyst material, a hydrogen ion conductive binder, that is, a fluorine-based Nafion Ionomer, and a water and/or alcohol solvent, This is coated on carbon cloth or carbon paper, which serves as both an electrode support for the catalyst layer and a gas diffusion layer, and then dried and thermally bonded to the hydrogen ion conductive electrolyte membrane.

In the catalyst layer, oxidation-reduction reaction of hydrogen and oxygen by the catalyst; movement of electrons by closely packed carbon particles; Securing passages for supplying hydrogen, oxygen and moisture and discharging excess gas after reaction; The movement of oxidized hydrogen ions must be performed simultaneously. Furthermore, in order to improve performance, the activation polarization must be reduced by increasing the area of the triple phase boundary where the supplied fuel, catalyst, and ion conductive polymer electrolyte membrane meet, and the interface between the catalyst layer and the electrolyte membrane and the catalyst layer It is necessary to uniformly bond the interface between the gas diffusion layer and the gas diffusion layer to reduce ohmic polarization at the interface. Therefore, in order to improve the performance of the fuel cell by maximally reducing the interfacial resistance between the catalyst layer and the electrolyte membrane, bonding strength between the catalyst layer and the electrolyte membrane is required during manufacturing of the MEA, and interfacial bonding between the catalyst layer and the electrolyte membrane is required during fuel cell operation. should be maintained

Accordingly, in recent years, technologies for uniformly bonding the interface between the catalyst layer and the electrolyte membrane and the interface between the catalyst layer and the gas diffusion layer have been actively developed, but the uniformity of the interface is still limited.

In addition, in the case of an MEA having the above structure, since an electrolyte membrane having a thick thickness is usually used, the transfer of hydrogen ions may be delayed, resulting in performance deterioration.

In addition, as the movement of hydrogen ions and the use time increase during fuel cell operation, the interface bonding between the catalyst layer and the electrolyte membrane and the interface between the catalyst layer and the gas diffusion layer are weakened and separated from each other. Thus, when applied to a fuel cell, performance degradation of the fuel cell may be caused.

In order to shorten the transit time of hydrogen ions, etc., the thickness of the electrolyte membrane must be reduced. To this end, there is a method of thinning the thickness of the porous support constituting the electrolyte membrane. Not only this greatly decreases, but there is a problem of poor economics and commerciality due to a high defect rate during the manufacture of the support, and in particular, there is a problem of poor durability of the electrolyte membrane.

In addition, hydrogen and oxygen in the air, which are the reaction gases of the fuel cell, crossover through the electrolyte membrane to promote the production of hydrogen peroxide. ) radicals (·OOH) and other oxygen-containing radicals (Oxygen-Containing Radicals) are generated. These radicals attack the ionomer electrolyte membrane to cause chemical degradation of the membrane and eventually cause a problem of lowering the performance of the fuel cell (voltage drop).

To prevent this, various antioxidants are used. For example, a primary antioxidant with a radical scavenger function and a secondary antioxidant with a hydrogen peroxide decomposer function (Secondary Antioxidant) ) is mixed and applied to the electrolyte membrane, but it is known that the use of such a primary antioxidant increases the antioxidant property, but causes a decrease in the long-term stability of the electrolyte membrane (S. Schlick et al., J. Phys Chem. C, 120, 6885 - 6890 (2016); S. Deshpande et al., Appl. Phys.

Therefore, in order to increase the commercialization of fuel cells, a new approach for improving the durability of electrolyte membranes is required.

Korean Patent Publication No. 2010-0077483 (published date: 2010.07.08)

S. Schlick et al., J. Phys. Chem. C, 120, 6885 - 6890 (2016); S. Deshpande et al., Appl. Phys. Lett., 8, 133113 (2005)

Existing radical scavengers such as CePO ₄ , Ce ₃ (PO ₄ ) ₄ , Zn ₃ (PO ₄ ) ₂ , CrPO ₄ , AlPO ₄ and FePO ₄ applied to existing electrolyte membranes have improved durability through antioxidant effects. However, due to the low conductivity of the antioxidant, there is a problem in that the performance of the electrolyte membrane is lowered by interfering with the movement of electrons and ions. In addition, although the role of antioxidant is important due to radicals generated by gas permeation at the opposite electrode, there is a problem in that a large amount of radical scavenger cannot be used. The present invention was devised in view of the above points, and developed a high durability improver for PEMFC electrolyte membranes that can act as an antioxidant as well as an antioxidant for existing radical scavengers, thereby making it a thin film electrolyte. It is intended to provide a composite electrolyte membrane for PEMFC in which the electrolyte membrane is applied to a membrane and combined with the electrolyte membrane in a multilayer structure, a membrane-electrode assembly for PEMFC using the same, and a high durability improver applied thereto.

The present invention for solving the above problems is a membrane-electrode assembly (MEA) for a PEMFC, an anode electrode including an anode catalyst layer; Composite electrolyte membrane for PEMFC (Polymer Electrolyte Membrane Fuel Cell); and a cathode electrode including a cathode catalyst layer, wherein the composite electrolyte membrane includes an electrolyte layer including a high durability improver; and a support layer, wherein the anode catalyst layer and the cathode catalyst layer include a Pt—C (platinum-carbon) catalyst.

As a preferred embodiment of the present invention, the anode electrode, composite electrolyte membrane and cathode electrode of the MEA for PEMFC of the present invention satisfy Equation 1 below.

[Equation 1]

B < A ≤ C

In Equation 1, A means the weight per unit area (mg/cm ² ) of platinum (Pt) derived from the Pt-C catalyst in the anode catalyst layer, and B is platinum derived from the high durability improver in the electrolyte layer of the composite electrolyte membrane ( Pt) means the weight per unit area (mg/cm ² ), and C means the weight per unit area (mg/cm ² ) of platinum (Pt) derived from the Pt—C catalyst in the cathode catalyst layer.

As a preferred embodiment of the present invention, in the MEA for PEMFC of the present invention, the content of the high durability improver in the electrolyte layer may increase from the anode electrode to the cathode electrode.

As a preferred embodiment of the present invention, the electrolyte membrane for the PEMFC may have a single-layer structure or a multi-layer structure.

As a preferred embodiment of the present invention, the composite electrolyte membrane of the MEA for PEMFC of the present invention is a composite electrolyte membrane in which an electrolyte layer, a first support layer, and a second electrolyte layer are sequentially stacked, and the first electrolyte layer And at least one layer selected from among the second electrolyte layer may include the high durability improver and the ionomer.

As a preferred embodiment of the present invention, the first electrolyte layer is an electrolyte layer in the direction of the anode electrode, the second electrolyte layer is an electrolyte layer in the direction of the cathode electrode, and the first electrolyte layer and the second electrolyte layer are the high durability Including the improver, the content of the high durability improver in the first electrolyte layer and the content of the high durability improver in the second electrolyte layer may be in a weight ratio of 0.05 to 0.95:1, preferably 0.10 to 0.90:1.

As a preferred embodiment of the present invention, the composite electrolyte membrane of the MEA for PEMFC of the present invention is a first electrolyte layer, a first support layer, a second electrolyte layer, a second support layer and a third electrolyte in the direction from the anode electrode to the cathode electrode. A composite electrolyte membrane in which layers are sequentially stacked; Or a sequentially stacked composite electrolyte membrane in which a first electrolyte layer, a first support layer, a second electrolyte layer, a second support layer, a third electrolyte layer, a third support layer, and a fourth electrolyte layer are sequentially stacked, Each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and the fourth electrolyte layer independently includes the high durability improver, but the content of the high durability improver in the electrolyte layer increases in the direction from the anode electrode to the cathode electrode. You may have a gradient.

As a preferred embodiment of the present invention, at least one layer selected from among the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and/or the fourth electrolyte layer further includes a cerium (Ce)-based radical scavenger. may also include

As a preferred embodiment of the present invention, in the MEA for the PEMFC of the present invention, the anode electrode and the cathode electrode may further include a gas diffusion layer in the direction of the other surface of the surface on which the composite electrolyte membrane is laminated.

As a preferred embodiment of the present invention, the average thickness of the composite electrolyte membrane for the PEMFC may be 5 to 30 μm.

In a preferred embodiment of the present invention, each of the first support layer, the second support layer and/or the third support layer may have a thickness of 0.1 to 10 μm.

In a preferred embodiment of the present invention, each of the first support layer, the second support layer, and/or the third support layer is a PTFE porous support having an average pore size of 0.080 to 0.200 μm and an average porosity of 60 to 90%. can include

In a preferred embodiment of the present invention, each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer and/or the fourth electrolyte layer may have a thickness of 1 to 20 μm.

In a preferred embodiment of the present invention, each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and/or the fourth electrolyte layer includes at least one selected from perfluorine-based sulfonated ionomer and hydrocarbon-based ionomer can do.

In a preferred embodiment of the present invention, each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and/or the fourth electrolyte layer contains CeZnO, CeO ₂ , Ru, Ag, and RuO ₂ in addition to the high durability improver. , WO ₃ , Fe ₃ O ₄ , CePO ₄ , CrPO _{4 , AlPO 4 ,} FePO ₄ , CeF ₃ , FeF ₃ , Ce ₂ (CO ₃ ) ₃ 8H ₂ O, Ce(CHCOO) ₃ H ₂ O, CeCl ₃ 6H ₂ O, Ce(NO ₃ ) ₆ 6H ₂ O, Ce(NH ₄ ) ₂ (NO ₃ ) ₆ , Ce(NH ₄ ) ₄ (SO ₄ ) ₄ 4H ₂ O and Ce(CH ₃ COCHCOCH ₃ ) A radical scavenger containing at least one selected from ₃ ·3H ₂ O may be further included.

In a preferred embodiment of the present invention, each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and/or the fourth electrolyte layer may further include at least one selected from hollow silica and a moisture absorbent. .

As a preferred embodiment of the present invention, the high durability enhancer includes a composite including platinum (Pt) particles and a carrier carrying the platinum particles, wherein the carrier includes CeO ₂ , GDC (Gd doped Ceria), IrO _{2 ,} SnO ₂ and It includes at least one selected from Ti ₄ O ₇ .

As a preferred embodiment of the present invention, it may include 0.01 to 6.00% by weight of the platinum and the balance of the carrier.

As a preferred embodiment of the present invention, the platinum is nano-sized platinum particles, and the platinum particles may be bonded to and integrated with the surface of the carrier.

As a preferred embodiment of the present invention, the particle size (D ₅₀ ) of the platinum particles is 0.1 to 50 nm, and the particle size (D ₅₀ ) of the carrier may be 10 to 2,000 nm.

As a preferred embodiment of the present invention, the GDC is a compound represented by the following Chemical Formula 1, and gadolinium (Gd) may be doped in a ceria lattice.

[Formula 1]

Gd _x Ce _1-x O _2-y

In Formula 1, x satisfies 0<x≤0.3, y is an oxygen vacancy value that makes the compound electrically neutral, and satisfies 0<y≤0.25.

As a preferred embodiment of the present invention, the high durability improver may have a BET specific surface area of 10 to 500 m ² /g.

As a preferred embodiment of the present invention, when the support is CeO ₂ , 0.01 to 6.00 wt% of platinum particles may be included in the total weight of the high durability improver.

As a preferred embodiment of the present invention, when the support is GDC, 0.01 to 5.00% by weight of platinum particles may be included in the total weight of the high durability improver.

As a preferred embodiment of the present invention, when the support is IrO ₂ , 0.01 to 4.5 wt% of platinum particles may be included in the total weight of the high durability improver.

As a preferred embodiment of the present invention, when the support is SnO ₂ , 0.01 to 3.0 wt% of platinum particles may be included in the total weight of the high durability improver.

As a preferred embodiment of the present invention, when the support is Ti ₄ O ₇ , 0.01 to 5.5% by weight of platinum particles may be included in the total weight of the high durability improver.

As a preferred embodiment of the present invention, the high durability improver of the present invention may include two or more of the above composites, the cerium-based composite including the platinum particles and CeO ₂ supporting the platinum particles as a support; and a non-cerium-based composite comprising the platinum particles and a support, wherein the support of the non-cerium-based composite is IrO _{2 ,} SnO ₂ and At least one selected from Ti ₄ O ₇ may be included.

As a preferred embodiment of the present invention, the high durability improver of the present invention may include the cerium-based composite and the non-cerium-based composite in a weight ratio of 1:0.1 to 50.

As a preferred embodiment of the present invention, the high durability improver of the present invention is the cerium-based composite; and a gadolidium-based composite including platinum (Pt) particles and a Gd doped Ceria (GDC) carrier represented by Chemical Formula 1 carrying the platinum particles.

As a preferred embodiment of the present invention, the high durability improver of the present invention is the cerium-based composite; and a gadolidium-based composite; may be included in a weight ratio of 1:0.05 to 10.

Another object of the present invention is to provide a polymer electrolyte fuel cell (PEMFC) including the MEA for PEMFC described above.

Since the high durability improver applied to the electrolyte layer of the composite electrolyte membrane of the MEA of the present invention not only serves as an antioxidant, which is a radical scavenger effect, but also serves as an antioxidant that reduces gas permeability, a separate radical scavenger is not added. The durability improvement effect of the electrolyte membrane is excellent even without the need, and the step of adding a radical scavenger can be omitted when manufacturing the electrolyte membrane. The composite electrolyte membrane for PEMFC prepared by introducing the high durability improver of the present invention has a thin thickness, excellent durability and dimensional stability, high tensile strength, and excellent performance, so it has excellent long-term stability and high efficiency. It is possible to provide a membrane-electrode assembly for a PEMFC and a polymer electrolyte fuel cell incorporating the same.

1a and 1b are schematic diagrams of a composite electrolyte membrane for a PEMFC according to a preferred embodiment of the present invention.
2 is a schematic diagram of a composite electrolyte membrane for a PEMFC according to another preferred embodiment of the present invention.
3 is a schematic diagram of a composite electrolyte membrane for a PEMFC according to another preferred embodiment of the present invention.
4 is a schematic diagram of a composite electrolyte membrane for a PEMFC according to another preferred embodiment of the present invention.
5 is a schematic diagram of a membrane-electrode assembly for a PEMFC according to a preferred embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are added to the same or similar components throughout the specification.

A membrane-electrode assembly (MEA) for a PEMFC of the present invention includes an anode electrode 200 including an anode catalyst layer 1 as schematically shown in FIG. 5A; A composite electrolyte membrane 100 for PEMFC (Polymer Electrolyte Membrane Fuel Cell); and a cathode electrode 300 including a cathode catalyst layer 2 .

In addition, as schematically shown in FIG. 5B, the anode electrode and the cathode electrode may further include gas diffusion layers 3 and 3' in the direction of the other surface of the surface on which the composite electrolyte membrane is laminated.

In the MEA for PEMFC of the present invention, the composite electrolyte membrane includes an electrolyte layer and a support layer, and the electrolyte layer of the composite electrolyte membrane includes a high durability improver, which will be described as follows.

[High durability improver]

The high durability enhancer serves to increase the durability of the electrolyte membrane by preventing the electrolyte membrane from deteriorating due to radicals generated during PEMFC operation. The high durability enhancer is in the form of a composite type powder, and includes platinum (Pt) particles and a carrier carrying the platinum particles. The high durability improver of the present invention of such a complex type simultaneously performs a radical scavenger function, which is an antioxidant function, and a gas permeability reduction function through hydrogen peroxide decomposition, which is an antioxidant function, secondarily, and also gas It can also perform decomposition and/or gas barrier functions and electron conductor functions.

The high durability enhancer includes 0.01 to 6.00% by weight of platinum particles and the balance of the carrier, preferably 0.01 to 5.50% by weight of platinum particles and the balance of the carrier, more preferably 0.10 to 5.00% by weight of platinum particles and A residual amount of the carrier may be included. At this time, if the platinum particle content of the total weight of the high durability improver is less than 0.01% by weight, the radical scavenging function is insufficient, and thus the deterioration prevention effect may be reduced. Since deterioration prevention efficiency may decrease, it is recommended to use it within the above range.

The high durability improver of the present invention is integrated with nano-sized platinum particles bonded to the surface of the carrier. For example, platinum particles may be bonded by depositing them on the surface of the carrier.

The particle size (D ₅₀ ) of the platinum particles is 0.1 to 50 nm, preferably 0.1 to 30 nm, and more preferably 3.0 to 20.0 nm. At this time, if the particle size (D ₅₀ ) of the platinum particle is 0.1 nm or less, it may be difficult to handle and difficult to manufacture a high durability improver, and if the particle size (D ₅₀ ) of the platinum particle exceeds 50 nm, the reaction area decreases and There may be a problem with platinum particles agglomeration.

The support is CeO ₂ , GDC (Gd doped Ceria), IrO _{2 ,} SnO ₂ and At least one selected from Ti ₄ O ₇ may be included.

CeO ₂ , IrO _{2 ,} SnO ₂ , Ti ₄ O ₇ is a catalytic material with a good oxygen generation reaction, and has excellent stability and high electrical conductivity in the case of supports used in a high voltage acidic environment, and is a stable material in a high voltage acidic environment. can play a role in increasing In addition, it is a material specialized for preventing corrosion of carbon by decomposing water when reverse voltage occurs due to lack of fuel during fuel cell operation, and it is a material that prevents water in the electrode from blocking pores or turning the fuel cell on or off. In this situation, a special situation occurs when fuel supply is insufficient, and at this time, CeO ₂ , IrO _{2 ,} SnO ₂ , Ti ₄ O ₇ can serve to increase the durability and stability of the fuel cell.

In addition, the GDC (Gd-doped Ceria) is an oxide doped with gadolinium (Gd) in a ceria lattice, and may be a compound represented by Chemical Formula 1 below.

[Formula 1]

Gd _x Ce _1-x O _2-y

In Formula 1, x satisfies 0<x≤0.3, preferably 0<x≤0.25, more preferably 0<x≤0.20, y is an oxygen vacancy value that makes the compound electrically neutral, and 0 <y≤0.25 is satisfied.

In addition, the optimum content of platinum particles in the high durability improver may be slightly different depending on the type of carrier.

When the carrier is CeO ₂ , the content of platinum particles may be 0.01 to 6.00 wt %, preferably 0.1 to 5.5 wt %, and more preferably 0.5 to 5.5 wt %, based on the total weight of the high durability improver.

In addition, when the carrier is GDC, the content of platinum particles in the total weight of the high durability improver may be 0.01 to 5.00 wt%, preferably 0.01 to 3.00 wt% of platinum, and more preferably 0.10 to 2.00 wt% of platinum.

In addition, when the carrier is IrO ₂ , the content of platinum particles in the total weight of the high durability improver may be 0.01 to 4.50 wt%, preferably 0.1 to 3.5 wt%, and more preferably 0.5 to 3.0 wt%.

In addition, when the carrier is SnO ₂ , the content of platinum particles based on the total weight of the high durability improver may be 0.01 to 3.00 wt%, preferably 0.1 to 2.5 wt%, and more preferably 0.3 to 2.0 wt%.

In addition, when the support is Ti ₄ O ₇ , the content of platinum particles based on the total weight of the high durability improver may be 0.01 to 5.50 wt%, preferably 0.1 to 4.5 wt%, and more preferably 0.5 to 3.5 wt%.

In addition, the high durability improver of the present invention may use a single type of composite (platinum particles + carrier), or use two types of composites to improve durability equal to or better than a single type of composite while using less or the same amount. can also be obtained.

For a specific example, the high durability improver of the present invention may include two or more of the above composites, and may include a cerium-based composite and a non-cerium-based composite, preferably a cerium-based composite and a non-cerium-based composite. : 0.1 to 50 may be included in a weight ratio.

For another specific example, the high durability enhancer may include two or more of the above composites, and may include a cerium-based composite and a gadolidium-based carrier composite, preferably a cerium-based composite and a gadolidium-based composite. 1: may be included in a weight ratio of 0.05 to 10.

In this case, the cerium-based composite refers to a composite including the platinum particles and CeO ₂ supporting the platinum particles as a support, and the non-cerium-based composite includes the platinum particles and IrO _{2 ,} SnO ₂ and Ti ₄ O ₇ refers to a composite including a support containing at least one selected from among. And, as a gadolidium-based carrier composite, the GDC composite means a composite including platinum (Pt) particles and a GDC (Gd doped Ceria) carrier represented by Formula 1 carrying the platinum particles.

In addition, the carrier may have a particle size (D ₅₀ ) of 10 to 2,000 nm, preferably 10 to 1,000 nm, more preferably 50 to 800 nm, and even more preferably 50 to 650 nm. At this time, if the particle size (D ₅₀ ) of the carrier is 10 nm or less, it may be difficult to attach the platinum particle size, and if the particle size (D ₅₀ ) of the carrier exceeds 2,000 nm, there may be a problem in that the reaction area decreases. there is.

The high durability improver of the present invention may have a BET surface area of 10 to 500 m ² /g, preferably 80 to 400 m ² /g, and more preferably 90 to 250 m ² /g.

[Composite Electrolyte Membrane]

Hereinafter, an electrolyte membrane for a PEMFC constituting an MEA will be described.

Among the MEA configurations of the present invention, the PEMFC electrolyte membrane may have a single-layer structure or a multi-layer structure, and an example of the multi-layer structure may be a composite electrolyte membrane as described below. At this time, the electrolyte layer of each layer of the composite electrolyte membrane may be formed with the electrolyte membrane forming solution, or may be formed with an electrolyte membrane forming solution having a different configuration.

Referring to FIG. 1A, the composite electrolyte membrane for a PEMFC (Polymer Electrolyte Membrane Fuel Cell) of the present invention has a structure in which a first electrolyte layer 21, a first support layer 11, and a second electrolyte layer 22 are sequentially stacked. And, at least one layer of the first electrolyte layer and / or the second electrolyte layer may include the above-described high durability improver.

In addition, at least one layer selected from among the first electrolyte layer and the second electrolyte layer may include the high durability improver and the ionomer.

In addition, at least one layer selected from among the first electrolyte layer and the second electrolyte layer may further include a cerium (Ce)-based radical scavenger.

The composite electrolyte membrane for PEMFC is an electrolyte membrane in which the first electrolyte layer, the first support layer, and the second electrolyte layer are sequentially stacked from the anode to the cathode when the membrane-electrode assembly for PEMFC is applied, and the following conditions ( A high durability improver may be included in the electrolyte layer to satisfy 1), and since the role and effect of the high durability improver is greater at the cathode than at the anode, the following condition (1) is satisfied PEMFC membrane-electrode It is advantageous in terms of performance and durability of the conjugate.

Condition (1) A ₁ ≤ A ₂

In the above condition (1), A ₁ represents the content of the high durability improver in the first electrolyte layer, and A ₂ represents the content of the high durability improver in the second electrolyte layer.

In addition, referring to FIG. 1B, the composite electrolyte membrane for a PEMFC (Polymer Electrolyte Membrane Fuel Cell) of the present invention includes a first electrolyte layer 21, a first support layer 11, a second electrolyte layer 22, and a second support. The layer 12 and the third electrolyte layer 23 may have a sequentially stacked structure.

Specifically, the composite electrolyte membrane for PEMFC of the present invention includes a first electrolyte layer 21, a first support layer 11 formed on one surface of the first electrolyte layer 21, and a first support layer 11 formed on one surface. It may include a second electrolyte layer 22, a second support layer 12 formed on one surface of the second electrolyte layer 22, and a third electrolyte layer 23 formed on one surface of the second support layer 12. Also, at least one of the first to third electrolyte layers may include the above-described high durability improver.

In the composite electrolyte membrane for PEMFC, when a membrane-electrode assembly for PEMFC is applied, a first electrolyte layer, a first support layer, a second electrolyte layer, a second support layer, and a third electrolyte layer are sequentially stacked from the anode direction to the cathode direction. It is a composite electrolyte membrane and may satisfy the following condition (2) or condition (3), and satisfying the following condition (2) or (3) is advantageous in terms of optimizing the effect of the high durability enhancer of the PEMFC membrane-electrode assembly.

Condition (2) A ₁ ≤ A ₂ ≤ A ₃

Condition (3) A ₂ ≤ A ₁ , A ₂ ≤ A ₃ , A ₁ ≤ A ₃

In the above conditions (2) and (3), A ₁ is the content of the high durability improver in the first electrolyte layer, A ₂ is the content of the high durability improver in the second electrolyte layer, and A ₃ is the content of the high durability improver in the third electrolyte layer Indicates the content of the enhancer.

In addition, referring to FIG. 2, the composite electrolyte membrane for PEMFC of the present invention includes a first electrolyte layer 21, a first support layer 11, a second electrolyte layer 22, a second support layer 12, a third The electrolyte layer 23, the third support layer 13, and the fourth electrolyte layer 24 may have a sequentially stacked structure.

Specifically, the composite electrolyte membrane for PEMFC of the present invention includes a first electrolyte layer 21, a first support layer 11 formed on one surface of the first electrolyte layer 21, and a first support layer 11 formed on one surface. A second electrolyte layer 22, a second support layer 12 formed on one surface of the second electrolyte layer 22, a third electrolyte layer 23 formed on one surface of the second support layer 12, and the third electrolyte layer (23) It may include a third support layer 13 formed on one surface and a fourth electrolyte layer 24 formed on one surface of the third support layer 13.

In addition, referring to FIG. 3, the composite electrolyte membrane for PEMFC of the present invention includes a fifth electrolyte layer 25, a fourth support layer 14, a first electrolyte layer 21, a first support layer 11, a second The electrolyte layer 22, the second support layer 12, the third electrolyte layer 23, the third support layer 13, and the fourth electrolyte layer 24 may have a sequentially stacked structure.

Specifically, the composite electrolyte membrane for PEMFC of the present invention includes a fifth electrolyte layer 25, a fourth support layer 14 formed on one surface of the fifth electrolyte layer 25, and a first layer formed on one surface of the fourth support layer 14. 1 electrolyte layer 21, a first support layer 11 formed on one surface of the first electrolyte layer 21, a second electrolyte layer 22 formed on one surface of the first support layer 11, and the second electrolyte layer (22) a second support layer 12 formed on one surface, a third electrolyte layer 23 formed on one surface of the second support layer 12, and a third support layer 13 formed on one surface of the third electrolyte layer 23 ) and a fourth electrolyte layer 24 formed on one surface of the third support layer 13. At this time, the fourth support layer 13 may be the same as the first support layer 11, the second support layer 12, and/or the third support layer 13 described above, and the fifth electrolyte layer 25 ) may be the same as the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23, and/or the fourth electrolyte layer 24 described above.

In addition, the composite electrolyte membrane for the PEMFC is formed with only one support layer of the first electrolyte layer and the second electrolyte layer, the second electrolyte layer and the third electrolyte layer, or the third electrolyte layer and the fourth electrolyte layer. There may be, and as a preferred embodiment, as shown in the schematic diagram in FIG. 4, the first electrolyte layer 21, the second electrolyte layer 22 formed on one surface of the first electrolyte layer, the second electrolyte layer 22 ) may include a support layer 11 formed on one surface, a third electrolyte layer 23 formed on one surface of the support layer 11, and a fourth electrolyte layer 24 formed on one surface of the third electrolyte layer 23 .

[support layer]

Each of the first support layer, the second support layer, and the third support layer of the present invention may use a general porous support used in the art, preferably PTFE (Polytetrafluoroethylene) having specific physical properties manufactured by the following manufacturing method A porous support may be included.

The PTFE porous support of the present invention includes a 1-1 step of preparing a paste by mixing and stirring PTFE powder and a lubricant; 1-2 steps of aging the paste; Steps 1 to 3 of extruding and rolling the aged paste to produce an unsintered tape; Steps 1 to 4 of drying the unsintered tape and then removing the liquid lubricant; Steps 1-5 of uniaxially stretching the unsintered tape from which the lubricant has been removed; Steps 1-6 of biaxially stretching the uniaxially stretched unsintered tape; It can be manufactured by performing a process including; and steps 1-7 of firing.

In step 1-1, the paste may include 15 to 35 parts by weight, preferably 15 to 30 parts by weight, more preferably 15 to 25 parts by weight, based on 100 parts by weight of the PTFE powder. When the lubricant is less than 15 parts by weight based on 100 parts by weight of the PTFE powder, the porosity may be lowered when forming the porous PTFE support by the biaxial stretching process described later, and when the lubricant is greater than 35 parts by weight, the size of the pores when forming the porous PTFE support is reduced. As it grows, the strength of the support may be weakened.

The average particle diameter of the PTFE powder is 300 μm to 800 μm. Preferably, it may be 450 μm to 700 μm, but is not limited thereto. The lubricant is a liquid lubricant, and various alcohols, ketones, esters, etc. can be used in addition to hydrocarbon oils such as liquid paraffin, naphtha, white oil, toluene, and xylene, and preferably selected from liquid paraffin, naphtha, and white oil One or more types may be used.

70℃?의 온도에서 12 ~ 24 시간 동안 숙성할 수 있고, 바람직하게는 35~60℃의 온도에서 16 ~ 20 시간 동안 숙성할 수 있다. 상기 숙성 온도가 35℃ 미만이거나 숙성 시간이 12 시간 미만일 경우, PTFE 파우더 표면에 윤활제 코팅이 불균일하게 되어 후술되는 2축 연신시 PTFE 다공성 지지체의 연신 균일성이 제한적일 수 있다.Next, the aging of the first and second steps is a preforming process, and the paste is 30

It can be aged for 12 to 24 hours at a temperature of 70 ° C., and preferably aged for 16 to 20 hours at a temperature of 35 to 60 ° C. When the aging temperature is less than 35° C. or the aging time is less than 12 hours, the lubricant coating on the surface of the PTFE powder becomes non-uniform, and thus the stretching uniformity of the porous PTFE support may be limited during biaxial stretching described later.

In addition, when the aging temperature exceeds 70 °C or the aging time exceeds 24 hours, there may be a problem in that the pore size of the porous PTFE support after the biaxial stretching process becomes too small due to evaporation of the lubricant.

Next, in the extrusion of the first to third steps, the aged paste is compressed in a compressor to produce a PTFE block, and then the PTFE block is subjected to a pressure of 0.069 to 0.200 Ton/cm ² , preferably 0.090 to 0.175 Ton/cm. It can be carried out by pressure extrusion at a pressure of ² .

At this time, when the extrusion pressure is less than 0.069 Ton/cm ² , the pore size of the porous support may increase and the strength of the porous support may be weakened, and when the pressure exceeds 0.200 Ton/cm ² , the pore size of the porous support after the biaxial stretching process may decrease. There may be a problem that becomes small.

In addition, the rolling of the first to third steps may be performed as a calendering process at 50 to 100 ° C. with a hydraulic pressure of 5 to 10 MPa. At this time, when the hydraulic pressure is less than 5 MPa, the pore size of the porous support may increase and the strength of the porous support may be weakened, and when the hydraulic pressure exceeds 10 MPa, there may be a problem in that the pore size of the porous support becomes small.

Next, the drying of steps 1 to 4 can be performed through a general drying method used in the art. For example, an unsintered tape manufactured by rolling is 1 to 5 M/min at a temperature of 100 to 200 ° C. It can be carried out while being transferred to the conveyor belt at a speed, preferably at a temperature of 140 to 190 ° C. and transferred at a speed of 2 to 4 M / min. At this time, when the drying temperature is 100 ° C or lower or the drying rate exceeds 5 M / min, bubbles may be generated during the stretching process due to non-evaporation of the lubricant, and when the drying temperature is 200 ° C or higher or the drying rate is 1 M / min. If it is less than min, the stiffness of the dried tape may increase and slip may occur during the stretching process.

Next, the uniaxial stretching of steps 1 to 5 is a process of stretching the unsintered tape from which the lubricant has been removed in the longitudinal direction, and uniaxial stretching is performed using a speed difference between rollers when transporting through rollers. . Further, in the uniaxial stretching, the unsintered tape from which the lubricant is removed is stretched 3 to 10 times in the longitudinal direction, preferably 6 to 9.5 times, more preferably 6.2 to 9 times, and even more preferably 6.3 to 8.2 times. good to do At this time, if the uniaxial stretching ratio is less than 3 times, sufficient mechanical properties cannot be secured, and if the uniaxial stretching ratio exceeds 10 times, the mechanical properties may rather decrease and the pores of the support may become too large.

In addition, uniaxial stretching is preferably performed at a stretching temperature of 260 to 350° C. and a stretching rate of 6 to 12 M/min, preferably at a stretching temperature of 270 to 330° C. and a stretching rate of 8 to 11.5 M/min. , If the stretching temperature during uniaxial stretching is less than 260 ° C or the stretching speed is less than 6 M / min, there may be a problem in that the plastic section occurs due to the increased heat load on the dry sheet, and the stretching temperature during uniaxial stretching is 350 If it exceeds ℃ or the stretching speed exceeds 12 M / min, there may be a problem that slip occurs during the uniaxial stretching process and the thickness uniformity is lowered.

Next, in the biaxial stretching of steps 1 to 6, stretching is performed in the width direction (direction perpendicular to uniaxial stretching) of the uniaxially stretched unsintered tape, and the width is widened in the transverse direction while the end is fixed. can be stretched However, it is not limited thereto, and stretching may be performed according to a stretching method commonly used in the art. In the present invention, the biaxial stretching may be performed by 15 to 50 times in the width direction, preferably 25 to 45 times, more preferably 28 to 45 times, and even more preferably 29 to 42 times. At this time, if the biaxial stretching ratio is 15 times or less, sufficient mechanical properties may not be secured, and even if it exceeds 50 times, mechanical properties are not improved, and the uniformity of physical properties in the longitudinal direction and / or width direction is deteriorated. Since there may be, it is preferable to perform stretching within the above range.

In addition, biaxial stretching is carried out at a stretching rate of 10 to 20 M/min at a stretching temperature of 150 to 260° C., preferably at a stretching rate of 11 to 18 M/min at a stretching temperature of 200 to 250° C. It is good, and if the biaxial stretching temperature is less than 150 ℃ or the stretching speed is less than 10 M / min, there may be a problem that the stretching uniformity in the transverse direction is lowered, and the biaxial stretching temperature exceeds 260 ℃, or the stretching speed If exceeds 20 M / min, there may be a problem in that the physical properties are lowered due to the occurrence of an unfired section.

Lastly, the firing of steps 1-7 is carried out at 350 to 450° C., preferably while moving the stretched porous support on a conveyor belt at a speed of 10 to 18 M/min, preferably 13 to 17 M/min. Preferably, it can be performed by applying a temperature of 380 to 440 ° C., more preferably 400 to 435 ° C., through which the stretching ratio can be fixed and the effect of improving strength can be achieved. During firing, when the firing temperature is less than 350 ° C, the strength of the porous support may be lowered, and when it exceeds 450 ° C, there may be a problem in that the physical properties of the support are lowered due to a decrease in the number of fibrils due to over-firing.

In addition, the PTFE porous support prepared by performing the steps 1-7 has a stretch ratio (or aspect ratio) in the uniaxial direction (longitudinal direction) and biaxial direction (width direction) of 1: 3.00 to 8.5, preferably 1 : 4.0 to 7.0, more preferably 1: 4.00 to 5.50, and even more preferably 1: 4.20 to 5.00, and it is high that the uniaxial and biaxial stretching ratios (or aspect ratios) are within the above range. It is preferable in terms of ensuring mechanical properties, proper pore size of the support, and proper current flow.

The prepared PTFE porous support of the present invention may have an average pore size of 0.080 μm to 0.200 μm, preferably 0.090 μm to 0.180 μm, more preferably 0.095 μm to 0.150 μm, and even more preferably 0.100 to 0.140 μm. . In addition, the porous PTFE support of the present invention may have an average porosity of 60% to 90%, more preferably 60.0% to 79.6%.

If the average pore size of the PTFE porous support of the present invention is less than 0.080 μm or the porosity is less than 60%, when the PTFE porous support is impregnated with an electrolyte to prepare an electrolyte membrane, the degree of impregnation of the electrolyte in the PTFE porous support is limited can In addition, when the average pore size exceeds 0.200 μm or the porosity exceeds 90%, the structure of the porous PTFE support is deformed when impregnated with the electrolyte, and product life may deteriorate due to deterioration in dimensional stability.

On the other hand, when measured according to ASTM D 882, the PTFE porous support of the present invention may satisfy Equation 2 below for modulus values in uniaxial direction and modulus in biaxial direction.

[Equation 2]

0 ≤ │ (uniaxial modulus - biaxial modulus) / (uniaxial modulus) × 100│ ≤ 54%, preferably 0 ≤ │ (uniaxial modulus - biaxial modulus) / (uniaxial modulus) modulus) × 100%│ ≤ 40%, more preferably 1 ≤ │ (uniaxial modulus - biaxial modulus) / (uniaxial modulus) × 100%│ ≤ 26%

In addition, when measured according to ASTM D 882, the PTFE porous support of the present invention may have a uniaxial (longitudinal) modulus of 40 MPa or more, preferably a uniaxial modulus of 50 MPa or more, more preferably Preferably, the uniaxial modulus may be 48 to 75 Mpa, more preferably 65 to 75 Mpa. In addition, the biaxial direction (width direction) modulus is 40 MPa or more, preferably the biaxial direction (width direction) modulus is 55 Mpa or more, more preferably 46 to 75 Mpa, still more preferably 55 to 75 Mpa can

In addition, when measured according to ASTM D882, the PTFE porous support of the present invention may have a tensile strength of 40 MPa or more in a uniaxial direction (longitudinal direction) and a tensile strength of 40 MPa or more in a biaxial direction (width direction), preferably 1 The tensile strength in the axial direction may be 50 MPa or more, more preferably the tensile strength in the uniaxial direction may be 54 to 65 Mpa. Also, preferably, the tensile strength in the biaxial direction may be 52 Mpa or more, and more preferably, the tensile strength in the biaxial direction may be 52 to 70 Mpa.

On the other hand, each of the first support layer, the second support layer, and the third support layer of the present invention has a thickness of 0.1 to 10 μm, preferably a thickness of 1 to 7 μm, more preferably a thickness of 1 to 5 μm, More preferably, it may have a thickness of 1.5 to 4 μm, and even more preferably 1.5 to 2.5 μm. If the thickness is less than 0.1 μm, there may be a problem in reducing tensile strength, and if the thickness exceeds 10 μm, There may be a disadvantageous problem of thinning.

In addition, each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and/or the fourth electrolyte layer independently includes the high durability improver, but the content of the high durability improver may vary for each electrolyte layer. For example, the composite electrolyte membrane for the PEMFC is sequentially stacked in the direction from the anode electrode to the cathode electrode, in which the first electrolyte layer, the first support layer, the second electrolyte layer, the second support layer and the third electrolyte layer are sequentially stacked. composite electrolyte membrane; Or, in the direction from the anode electrode to the cathode electrode, the first electrolyte layer, the first support layer, the second electrolyte layer, the second support layer, the third electrolyte layer, the third support layer and the fourth electrolyte layer are sequentially stacked sequentially. In the case of a laminated composite electrolyte membrane, the content of the high durability improver in the electrolyte layer is adjusted so that the content of the high durability improver in the electrolyte layer increases as the distance from the anode electrode increases, and the high durability improver in the electrolyte layer moves from the anode electrode to the cathode electrode. It can be made to have a gradient in which the content increases.

For example, the content of the high durability improver in the first electrolyte layer and the second electrolyte layer is 0.05 to 0.95: 1 weight ratio, preferably 0.10 to 0.90: 1 weight ratio, more preferably 0.20 to 0.70: 1 weight ratio. A composite electrolyte membrane may be prepared by adjusting the content of the high durability improver.

In addition, the high durability improver content ratio of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and the fourth electrolyte layer is preferably 0 to 0.70: 0.05 to 0.80: 0.1 to 0.99: 1 weight ratio. Preferably, the weight ratio is 0.10 to 0.60: 0.20 to 0.70: 0.30 to 0.85: 1, but the content of the high durability improver is adjusted to increase the content of the high durability improver from the first electrolyte layer to the fourth electrolyte layer. A composite electrolyte membrane can be manufactured. there is.

Next, each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23 and the fourth electrolyte layer 24 of the present invention is a perfluorine-based sulfonated ionomer (PFSA ionomer) and a hydrocarbon It may include an ionomer comprising at least one selected from among group ionomers.

The perfluorine-based sulfonated ionomer of the present invention may include at least one selected from Nafion, Flemion, aquivion, and Aciplex, and is preferably aquivion. ) may be included.

The hydrocarbon-based ionomer may include at least one selected from polyarylene sulfone (PAES)-based, polyether-ether ketone (PEEK)-based, and polyimide (PI)-based.

In addition, the ionomer not only constitutes each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23, and the fourth electrolyte layer 24, but also the first support layer 11 And / or may be included in the pores of the second support layer (12).

On the other hand, each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23, and the fourth electrolyte layer 24 of the present invention may include a high durability improver, and the high durability The improver includes platinum (Pt) and a carrier carrying the platinum particles, and specific components and characteristics of the high durability improver are as described above.

In addition, when preparing an electrolyte solution for forming an electrolyte layer (or electrolyte membrane), 0.01 to 20% by weight of the high durability improver and the remaining amount of the ionomer may be included in the total weight of the electrolyte solution, preferably 0.1 to 20% by weight of the high durability improver It may include 10% by weight and the remaining amount of the ionomer, more preferably 0.1 to 1.0% by weight of the high durability improver and the remaining amount of the ionomer. At this time, if the content of the high durability improver is less than 0.01% by weight, the amount used may be too small to prevent deterioration of the electrolyte layer (or electrolyte membrane), and if the content of the high durability improver exceeds 20% by weight, it acts as an impurity Since a problem of lowering the ionic conductivity may occur, it is recommended to use it within the above range.

In addition, each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23, and the fourth electrolyte layer 24 is a radical scavenger for PEMFC in addition to the ionomer and the high durability improver ( radical scavenger) may be further included.

The radical scavenger for PEMFC of the present invention is a CeZnO metal oxide having a ZnO crystal structure doped with cerium ions by mixing a Ce precursor aqueous solution with a [Zn(OH) ₄ ] ^2- containing solution and performing a reduction reaction. It can be prepared by forming particles. Here, "ZnO crystal structure doped with Ce ions" means that a crystal structure in which some of Zn atoms are substituted with Ce atoms is newly formed in a ZnO crystal structure having a wurtzite or the like crystal structure.

More specifically, a first step of dissolving the Zn precursor in alcohol to prepare a Zn precursor solution and then raising the temperature of the Zn precursor solution; A second step of preparing a [Zn(OH) ₄ ] ^2- containing solution; A third step of forming CeZnO metal oxide particles having a ZnO crystal structure doped with Ce ions by mixing a Ce precursor aqueous solution with a [Zn(OH) ₄ ] ^2- containing solution and performing a reduction reaction; a fourth step of recovering and washing the CeZnO metal oxide particles; And a fifth step of drying the washed CeZnO metal oxide particles; a radical scavenger for PEMFC can be manufactured by performing a process including. For a more detailed description of this, Republic of Korea Patent Registration No. 10-1860870 by the same applicant may be inserted as a reference.

In addition, the radical scavenger for the PEMFC may include a cerium-based radical scavenger, and the cerium-based radical scavenger has a crystal structure composed of cerium (Ce) atoms, zinc (Zn) atoms, and oxygen (O) atoms. As a metal oxide particle having, as a preferred example, in a ZnO crystal structure having a crystal structure such as wurtzite, some of the Zn atoms may have a crystal structure in which Ce atoms are substituted.

In addition, the radical scavenger for the PEMFC may include 12 to 91 wt% of Ce, 7 to 84.5 wt% of Zn, and a residual amount of O (oxygen atoms), preferably 13.40 to 89.20 wt% of Ce and 7.55 to 7.55 to Zn. 88.20% by weight and the balance of O. And, it may further contain other unavoidable impurities.

In addition, the radical scavenger for PEMFC of the present invention is CeZnO, CeO ₂ , Ru, Ag, RuO ₂ , WO ₃ , Fe ₃ O ₄ , CePO ₄ , CrPO ₄ , AlPO ₄ , FePO in addition to the cerium-based radical scavenger. ₄ , CeF ₃ , FeF ₃ , Ce ₂ (CO ₃ ) ₃ 8H ₂ O, Ce(CHCOO) ₃ H ₂ O, CeCl ₃ 6H ₂ O, Ce(NO ₃ ) ₆ 6H ₂ O, Ce( At least one selected from NH ₄ ) ₂ (NO ₃ ) ₆ , Ce(NH ₄ ) ₄ (SO ₄ ) ₄ 4H ₂ O and Ce(CH ₃ COCHCOCH ₃ ) ₃ 3H ₂ O, or a cerium-based radical In addition to the scavenger, the radical scavenger may be additionally used.

In addition, the radical scavenger may have a particle size (D ₅₀ ) of 500 nm or less, preferably 300 nm or less, and more preferably 200 to 300 nm, when analyzed by a DLS (Dynamic Light Scattering) nanoparticle size analyzer.

On the other hand, each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and the fourth electrolyte layer of the present invention contains 0.001 to 10 parts by weight of a radical scavenger for PEMFC based on 100 parts by weight of the perfluorine-based sulfonated ionomer, preferably may include 0.01 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, if it is included in less than 0.001 parts by weight, there may be a problem with poor durability, and if it exceeds 10 parts by weight, durability is improved, but ion There may be a problem in that the performance of the composite electrolyte membrane of the present invention is deteriorated due to low conductivity.

In addition, the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23, and the fourth electrolyte layer 24, respectively, in addition to the ionomer and the high durability improver, are hollow silica and/or The described radical scavenger for PEMFC may be further included.

The hollow silica may be spherical and have an average particle diameter of 10 to 300 nm, more preferably 10 to 100 nm. Here, the particle size means the diameter when the shape of the hollow silica is spherical, and when it is not spherical, it means the maximum distance among straight line distances from one arbitrary point to another point on the surface of the hollow silica.

In addition, each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23, and the fourth electrolyte layer 24 of the present invention is at least one selected from zeolite, titania, zirconia, and montmorillonite. A moisture absorbent may be further included.

On the other hand, each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23 and the fourth electrolyte layer 24 of the present invention has a thickness of 1 to 10 μm, preferably 1 to 10 μm. It may have a thickness of 8 μm, more preferably a thickness of 2 to 5 μm, and even more preferably a thickness of 2.5 to 4.5 μm, and if the thickness is less than 1 μm, there may be a problem in that the tensile strength decreases, and If it exceeds ㎛, there may be a disadvantageous problem in thinning.

In addition, each of the first electrolyte layer 21, the second electrolyte layer 22, the third electrolyte layer 23 and the fourth electrolyte layer 24 of the present invention has a -SO ₃ H group equivalent (EW: equivalent) weight) is 1,100 or less, preferably 900 or less, more preferably 500 to 900, still more preferably 600 to 830, even more preferably 680 to 750, and if the equivalent of -SO ₃ H group is 1,100 If it exceeds , there may be a problem of deteriorating performance.

Furthermore, the composite electrolyte membrane for PEMFC applied to the MEA of the present invention has a rate of dimensional change in the MD direction (= longitudinal direction) measured by the following relational expression 1 of 10% or less, preferably 0 to 5%, more preferably 0 to 5%. 3%, more preferably 0.5 to 2%, and the dimensional change rate in the TD direction (= width direction) measured by the following relational expression 1 is 10% or less, preferably 2 to 8%, more preferably 3 ~ 7%, more preferably 4 ~ 6%.

[Relationship 1]

In Equation 1, A represents the initial length of the composite electrolyte membrane for PEMFC, and B represents the length measured after leaving the composite electrolyte membrane for PEMFC at a temperature of 80 ° C. for 20 minutes.

As described above, the composite electrolyte membrane for PEMFC of the present invention shows a low rate of dimensional change not only in the MD direction but also in the TD direction, so that the dimensional stability is remarkably excellent.

On the other hand, the composite electrolyte membrane for the PEMFC may have an average thickness of 5 to 30 μm, preferably 7 to 20 μm, more preferably 10 to 18 μm, and even more preferably 12 to 16 μm, and thus have a thin thickness. It is not only excellent in durability and dimensional stability, but also has high tensile strength and excellent performance.

In addition, when the composite electrolyte membrane for the PEMFC is an electrolyte membrane in which the first electrolyte layer, the first support layer, and the second electrolyte layer are sequentially stacked, the following condition (4) may be satisfied.

Condition (4) B ₁ ≤ A ₁ , B ₁ ≤ A ₂

In condition (4), A ₁ represents the thickness of the first electrolyte layer, A ₂ represents the thickness of the second electrolyte layer, and B ₁ represents the thickness of the first support layer.

In addition, in the present invention, when the composite electrolyte membrane for the PEMFC is a composite electrolyte membrane in which the first electrolyte layer, the first support layer, the second electrolyte layer, the second support layer, and the third electrolyte layer are sequentially stacked, the following condition (5 ) and (6) can both be satisfied.

Condition (5) B ₁ ≤ A ₁ , B ₁ ≤ A ₂ , B ₁ ≤ A ₃

Condition (6) B ₂ ≤ A ₁ , B ₂ ≤ A ₂ , B ₂ ≤ A ₃

In condition (5), A ₁ is the thickness of the first electrolyte layer 21, A ₂ is the thickness of the second electrolyte layer 22, A ₃ is the thickness of the third electrolyte layer 23, and B ₁ is Represents the thickness of the first support layer 11, and in the above condition (6), A ₁ is the thickness of the first electrolyte layer 21, A ₂ is the thickness of the second electrolyte layer 22, A ₃ is the thickness of the first electrolyte layer 21 3The thickness of the electrolyte layer 23, B ₂ represents the thickness of the second support layer 12.

In addition, in the present invention, if the composite electrolyte membrane for PEMFC does not satisfy both conditions (5) and (6), there may be a problem in that uniformity is lowered.

)은 하기 범위를 만족할 수 있다.In addition, the composite electrolyte membrane for PEMFC of the present invention has the value of condition (7) (condition (7):

) may satisfy the following range.

1.5 ≤ condition (7) value ≤ 12, preferably 1.5 ≤ condition (7) value ≤ 9, more preferably 2 ≤ condition (7) value ≤ 7, still more preferably 2.2 ≤ condition (7) value ≤ 5 , even more preferably 2.5 ≤ condition (7) value ≤ 3.0

In condition (7), A ₁ is the thickness of the first electrolyte layer 21, A ₂ is the thickness of the second electrolyte layer 22, A ₃ is the thickness of the third electrolyte layer 23, and B ₁ is The thickness of the first support layer 11, B ₂ represents the thickness of the second support layer 12.

If the value of condition (7) is less than 1.5, there may be a problem in that the composite electrolyte membrane is not manufactured, and if it exceeds 12, there may be a problem in that durability is lowered.

)를 만족할 수 있다.In addition, in the present invention, the MEA for the PEMFC is the value of condition (8) (condition (8):

) can be satisfied.

0.2 ≤ condition (8) value ≤ 10, preferably 0.5 ≤ condition (8) value ≤ 8, more preferably 1.0 ≤ condition (8) value ≤ 6, still more preferably 1.5 ≤ condition (8) value ≤ 4

In condition (8), A ₁ represents the thickness of the first electrolyte layer 21, A ₂ represents the thickness of the second electrolyte layer 22, and A ₃ represents the thickness of the third electrolyte layer 23.

If the value of condition (8) is less than 0.2, there may be a problem of deterioration in durability, and if it exceeds 10, there may be a problem of deterioration in performance.

[Method for manufacturing composite electrolyte membrane for PEMFC]

In addition, the composite electrolyte membrane for PEMFC of the present invention can be manufactured by performing a process including the first to fourth steps.

First, in the first step of the manufacturing method of the composite electrolyte membrane, a first support layer and a second support layer may be prepared, respectively. At this time, a PTFE (Poly tetra fluoro ethylene) porous support may be used as the first support layer and the second support layer, and the usable PTFE porous support is the same as the previously described PTFE porous support and manufacturing method.

Next, in the second step of the manufacturing method of the composite electrolyte membrane for the PEMFC, a first electrolyte layer may be formed on one side of the first support layer prepared in the first step, and a third layer on one side of the second support layer prepared in the first step. An electrolyte layer may be formed.

Specifically, in the second step of the manufacturing method of the composite electrolyte membrane for PEMFC, the ionomer mixture solution is applied to one surface of the first support layer, or one surface of the first support layer is impregnated with the ionomer mixture solution, and then dried. An electrolyte layer may be formed.

In addition, the third electrolyte layer may be formed by applying the ionomer mixture solution to one surface of the second support layer or impregnating one surface of the second support layer with the ionomer mixture solution and then drying it.

The drying of the second step may be performed by applying heat of 60 to 200 ° C. for 1 minute to 30 minutes, respectively, or preferably by applying heat of 70 to 150 ° C. for 15 minutes to 25 minutes. At this time, if the drying temperature is less than 60 ° C, the liquid retention of the solution containing the ionomer impregnated in the first support layer and / or the second support layer may be reduced, and if it exceeds 200 ° C, the electrolyte membrane and / or membrane - Bondability with electrodes may deteriorate during manufacture of electrode assemblies.

Next, in the third step, a second electrolyte layer may be formed on the other surface of the first support layer prepared in the first step.

Specifically, the third step is a process of forming a second electrolyte layer on the other surface of the first support layer on which the first electrolyte layer is formed, and the ionomer mixture solution is applied to the other surface of the first support layer or the other surface of the first support layer. After being impregnated with the ionomer mixed solution, it may be dried to form a second electrolyte layer.

The drying of the third step may be performed by applying heat of 60 to 200° C. for 1 minute to 30 minutes, or preferably by applying heat of 70 to 150° C. for 5 minutes to 15 minutes. At this time, if the drying temperature is less than 60 ° C, the liquid retention of the ionomer mixed solution impregnated in the first support layer may deteriorate, and if it exceeds 200 ° C, the adhesion with the electrode during the manufacture of the electrolyte membrane and / or membrane-electrode assembly may deteriorate. It can be.

The ionomer mixed solution in the second and third steps includes an ionomer containing at least one selected from perfluorine-based sulfonated ionomer and hydrocarbon-based ionomer; And it may include the high durability improver described above.

In addition, the ionomer mixed solution may further include at least one selected from the aforementioned radical scavenger, hollow silica, and moisture absorbent.

Finally, in the fourth step, the second electrolyte layer is laminated on the other surface of the second support layer prepared in the first step, and heat treatment is performed to form the first electrolyte layer, the first support layer, the second electrolyte layer, the second support layer, and the second support layer. A composite electrolyte membrane for a PEMFC of the present invention in which three electrolyte layers are sequentially stacked can be manufactured.

Specifically, the fourth step is a step of stacking and integrating a first support layer having a first electrolyte layer formed on one side and a second electrolyte layer formed on the other side, and a second support layer having a third electrolyte layer formed on one side, The second electrolyte layer and the second support layer formed on the other surface of the first support layer are stacked so as to contact each other, and heat-treated to sequentially form the first electrolyte layer, the first support layer, the second electrolyte layer, the second support layer, and the third electrolyte layer. It is possible to manufacture a composite electrolyte membrane for PEMFC of the present invention laminated with.

The heat treatment of the fourth step may be performed at 100 to 200 ° C for 1 minute to 20 minutes, preferably at 140 to 180 ° C for 1 minute to 15 minutes, and when the heat treatment temperature is less than 100 ° C or the heat treatment time is less than 1 minute The liquid retention properties of the first electrolyte layer, the second electrolyte layer, and/or the third electrolyte layer may be deteriorated, and when the heat treatment temperature exceeds 200° C., between the first, second, and third electrolyte layers and the first and second support layers The adhesiveness (combinability) of may be lowered.

In the first support layer and/or the second support layer of the composite electrolyte membrane subjected to the heat treatment in the fourth step, the volume of closed pores may be 85 vol% or more, preferably 90 vol% or more, based on the total pore volume.

[Membrane-electrode assembly for PEMFC]

Referring to FIG. 5, the MEA for PEMFC of the present invention includes an anode electrode (oxidation electrode) 200 including an anode catalyst layer, the aforementioned composite electrolyte membrane 100 for PEMFC of the present invention, and a cathode. A cathode electrode (reduction electrode) 300 including an electrode layer is included.

The MEA for PEMFC of the present invention includes an anode electrode 200 and a cathode electrode 300 positioned opposite to each other with a composite electrolyte membrane 100 interposed therebetween.

The MEA for PEMFC of the present invention may be formed by disposing the anode electrode 200, the composite electrolyte membrane 100, and the cathode electrode 300, respectively, and then fastening them, or by compressing them at high temperature and high pressure.

The anode catalyst layer 1 of the anode electrode is a layer into which an oxidation catalyst is introduced, and a metal catalyst or a metal catalyst supported on a carbon-based support may be used as the oxidation catalyst. Representatively, one or more selected from the group consisting of platinum, ruthenium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and platinum-transition metal alloy may be used as the metal catalyst. In addition, as the carbon-based support, graphite (graphite), carbon black, acetylene black, Denka black, Ketcheon black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon nanoring, carbon nano It may include at least one selected from the group consisting of wire, fullerene, and super P.

The cathode catalyst layer 2 of the cathode electrode is a layer into which a reduction catalyst is introduced, and a metal catalyst or a metal catalyst supported on a carbon-based support may be used as the reduction catalyst. Representatively, one or more selected from the group consisting of platinum, ruthenium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and platinum-transition metal alloy may be used as the metal catalyst. In addition, as the carbon-based support, graphite (graphite), carbon black, acetylene black, Denka black, Ketcheon black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon nanoring, carbon nano It may include at least one selected from the group consisting of wire, fullerene, and super P.

As the oxidation catalyst of the anode catalyst layer (1) and the reduction catalyst of the cathode catalyst layer (2), platinum (Pt-C) supported on a carbon-based support is introduced as a metal catalyst (metal catalyst-C) supported on a carbon-based support. In this case, it is advantageous in terms of electrochemical performance and long-life stability of the MEA to introduce the oxidation catalyst and the reduction catalyst into the anode catalyst layer and the cathode catalyst layer so that the anode electrode, the composite electrolyte membrane, and the cathode electrode satisfy Equation 1 below.

[Equation 1]

B < A < C, preferably B < A < C

In Equation 1, A means the weight per unit area (mg/cm ² ) of platinum (Pt) derived from the Pt-C catalyst in the anode catalyst layer, and B is platinum derived from the high durability improver in the electrolyte layer of the composite electrolyte membrane ( Pt) means the weight per unit area (mg/cm ² ), and C means the weight per unit area (mg/cm ² ) of platinum (Pt) derived from the Pt—C catalyst in the cathode catalyst layer.

For example, while satisfying Equation 1, the Pt content (A) in the anode catalyst layer is 0.30 to 0.50 mg/cm ² , and the Pt content in the electrolyte layer of the composite electrolyte membrane is 0.02 to 0.08 mg/cm ² , in the cathode catalyst layer. The MEA may be manufactured such that the Pt content (C) satisfies 0.20 to 0.40 mg/cm ² .

In addition, the anode electrode and the cathode electrode of the MEA of the present invention may further include gas diffusion layers 3 and 3' in the direction of the other surface of the surface on which the composite electrolyte membrane is laminated (see B in FIG. 5).

The gas diffusion layer 3 formed on the anode catalyst layer may be provided to prevent rapid diffusion of fuel injected into the fuel cell and to prevent a decrease in ion conductivity. In addition, the gas diffusion layer 3 can control the diffusion rate of fuel through heat treatment or electrochemical treatment. In addition, the gas diffusion layer 3 serves as a current conductor between the composite electrolyte membrane 100 for PEMFC and the anode catalyst layer 1, and becomes a passage for gas as a reactant and water as a product. Therefore, the gas diffusion layer 3 may have a porous structure having a porosity of 20% to 90% so that gas can pass through. And, the thickness of the gas diffusion layer 3 may be appropriately adopted as needed, and may be, for example, 100 to 400 μm. When the thickness of the gas diffusion layer 3 is less than 100 μm, its application effect may be insignificant, and when the thickness of the gas diffusion layer 3 exceeds 400 μm, the movement of reactant gas may become difficult.

In addition, the gas diffusion layer 3' formed on the cathode catalyst layer may be provided to prevent rapid diffusion of gas injected into the cathode electrode 300 and uniformly disperse the gas injected into the cathode electrode 300. there is. Also, the gas diffusion layer 3' may be a passage for gas as a reactant and water as a product. Accordingly, the gas diffusion layer 3' may have a porous structure having a porosity of 20% to 90% so that gas can pass through easily. The thickness of the gas diffusion layer 3' may be appropriately selected as needed, and may be, for example, 100 to 400 μm. When the thickness of the cathode gas diffusion layer 3′ is less than 100 μm, the application effect thereof may be insignificant, and when the thickness of the gas diffusion layer 3′ exceeds 400 μm, the movement of the reactant gas may become difficult. .

Each of the gas diffusion layers 3 and 3' may be formed of a carbon-based material and a fluorine-based resin. Carbon-based materials include graphite, carbon black, acetylene black, Denka black, Kechen black, activated carbon, mesoporous carbon, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon nano rings, carbon nanowires, and fullerenes (C60). And it may include one or more selected from the group consisting of super P, but is not limited thereto. In addition, as the fluorine-based resin, polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose acetate, polyvinylidene fluoride-hexafluoropropylene copolymer, or styrene-butadiene rubber (SBR) It may include one or more selected from the group consisting of. In addition, the fuel may be a liquid fuel such as formic acid solution, methanol, formaldehyde, or ethanol.

On the other hand, a polymer electrolyte membrane fuel cell according to an embodiment of the present invention includes at least one electricity generating unit generating electrical energy through an oxidation reaction of a fuel and a reduction reaction of an oxidizing agent, and supplying the aforementioned fuel to the electricity generating unit. It is configured to include a fuel supply unit for supplying an oxidizer and an oxidizer gap unit for supplying an oxidizer to the electricity generator.

An electricity generator may be configured by including one or more membrane-electrode assemblies of the present invention, and having separators for supplying fuel and an oxidizer disposed at both ends of the membrane-electrode assembly of the present invention. At least one of these electricity generators may form a stack.

At this time, since the arrangement form or manufacturing method of the polymer electrolyte membrane fuel cell of the present invention can be formed without limitation as long as it is applicable to the polymer electrolyte membrane fuel cell, it can be applied in various ways with reference to the prior art.

Although the present invention will be described in more detail through the following examples, the following examples are not intended to limit the scope of the present invention, which should be interpreted to aid understanding of the present invention.

[Example]

Example 1-1: High durability improver (Pt/CeO ₂ composite) and preparation of electrolyte membrane forming solution

(1) Manufacture of high durability improver

Particle size (D ₅₀ ) of 177 nm CeO ₂ was prepared as a carrier.

Next, a process of inducing a reduction reaction from platinum in a precursor state to platinum metal in a nanoparticle state is performed by preparing platinum in a precursor state, mixing the CeO ₂ carrier therein, and using a reducing agent to obtain platinum nanoparticles. A high durability improver (Pt/CeO ₂ composite) integrated by depositing on the surface of the carrier was prepared.

The content of the platinum nanoparticles in the prepared high durability enhancer was 0.10% by weight, and the average particle size (D ₅₀ ) of the platinum particles was about 5 nm.

(2) Preparation of electrolyte membrane forming solution

A perfluorine sulfonic acid-based ionomer (trade name: Aquivion ^® D72-25DS, Solvay) having an equivalent weight of -SO ₃ H group of 720 was prepared.

An electrolyte membrane forming solution was prepared by mixing 0.5 wt% of the high durability enhancer (Pt/CeO ₂ composite) and the remaining amount of the ionomer.

Examples 1-2 to 1-4 and Comparative Examples 1-1 to 1-2

An electrolyte membrane forming solution was prepared in the same manner as in Example 1-1, but the platinum particle content of the high durability improver (Pt/CeO ₂ composite) was 1.0% by weight, 3.0% by weight, and 5.5% by weight, as shown in Table 1 below. Electrolyte film forming solutions were prepared, respectively, and Examples 1-2 to 1-4 were carried out, respectively.

However, in Comparative Example 1-1, only CeO ₂ was used as a durability improver without using platinum particles, and in Comparative Example 1-2, a high durability improver was prepared so that the platinum particles were 6.0% by weight.

Example 2-1: High durability improver (Pt/IrO ₂ composite) and preparation of electrolyte membrane forming solution

(1) Manufacture of high durability improver

IrO ₂ having a particle size (D ₅₀ ) of 242 nm was prepared as a support, and the platinum precursor used in Example 1-1 was prepared.

Next, platinum in a precursor state is prepared, a support is mixed therein, and a reducing agent is used to induce a reduction reaction from platinum in a precursor state to platinum metal in a nanoparticle state, so that platinum nanoparticles are formed on the surface of the carrier. It was deposited on to prepare an integrated high durability enhancer (Pt/IrO ₂ composite).

The content of the platinum nanoparticles in the prepared high durability enhancer was 1.0% by weight, and the average particle size (D ₅₀ ) of the platinum particles was about 12 nm.

(2) Preparation of electrolyte membrane forming solution

An electrolyte membrane forming solution was prepared by mixing 0.5% by weight of the high durability improver (Pt/IrO ₂ composite) and the remaining amount of the ionomer using the same perfluorine sulfonic acid ionomer as in Example 1-1.

Example 2-2

A high durability improver (Pt/IrO ₂ composite) was prepared in the same manner as in Example 2-1, but the platinum content was 0.1% by weight, and then the high durability improver (Pt/IrO ₂ composite) ) 0.5% by weight and the remaining amount of the ionomer was mixed to prepare an electrolyte membrane forming solution.

Example 3-1: High durability improver (Pt/SnO ₂ composite) and preparation of electrolyte membrane forming solution

(1) Manufacture of high durability improver

SnO ₂ having a particle size (D ₅₀ ) of 353 nm was prepared as a carrier, and the platinum precursor used in Example 1 was prepared.

Next, platinum in a precursor state is prepared, a support is mixed therein, and a reducing agent is used to induce a reduction reaction from platinum in a precursor state to platinum metal in a nanoparticle state, so that platinum nanoparticles are formed on the surface of the carrier. It was deposited on to prepare an integrated high durability improver (Pt/SnO ₂ composite).

The content of the platinum nanoparticles in the prepared high durability enhancer was 1.0% by weight, and the average particle size (D ₅₀ ) of the platinum particles was about 9 nm.

(2) Preparation of electrolyte membrane forming solution

An electrolyte membrane forming solution was prepared by mixing 0.5 wt% of the high durability improver (Pt/SnO ₂ composite) and the remaining amount of the ionomer using the same perfluorine sulfonic acid ionomer as in Example 1.

Example 3-2

A high durability improver (Pt/SnO ₂ composite) was prepared in the same manner as in Example 3-2, but the platinum content was 0.1% by weight, and then the high durability improver (Pt/SnO ₂ composite) ) 0.5% by weight and the remaining amount of the ionomer was mixed to prepare an electrolyte membrane forming solution.

Example 4-1: High durability improver (Pt/Ti ₄ O ₇ composite) and preparation of electrolyte membrane forming solution

(1) Manufacture of high durability improver

Ti ₄ O ₇ having a particle size (D ₅₀ ) of 502 nm was prepared as a support, and the platinum precursor used in Example 1 was prepared.

Next, platinum in a precursor state is prepared, a support is mixed therein, and a reducing agent is used to induce a reduction reaction from platinum in a precursor state to platinum metal in a nanoparticle state, so that platinum nanoparticles are formed on the surface of the carrier. It was deposited on to prepare an integrated high durability improver (Pt/Ti ₄ O ₇ composite).

The content of the platinum nanoparticles in the prepared high durability enhancer was 1.0% by weight, and the average particle size (D ₅₀ ) of the platinum particles was about 7 nm.

(2) Preparation of electrolyte membrane forming solution

An electrolyte membrane forming solution was prepared by mixing 0.5 wt% of the high durability improver (Pt/Ti ₄ O ₇ composite) and the remaining amount of the ionomer using the same perfluorine sulfonic acid ionomer as in Example 1-1.

Example 4-2

A high durability improver (Pt/Ti ₄ O ₇ composite) was prepared in the same manner as in Example 4-2, but the platinum content was 0.1% by weight, and then the high durability improver (Pt/Ti ₄ O ₇ composite) and the remaining amount of the ionomer were mixed to prepare an electrolyte membrane forming solution.

Example 5

The same electrolyte film forming solution as in Example 1-1 was prepared, but the content of the high durability improver was prepared to be 17.0% by weight.

Example 6-1

(1) Manufacture of high durability improver

GDC represented by Formula 1-1 was prepared as a support by a method of obtaining a coprecipitate by dropping a mixed solution of a cerium precursor (cerium nitrate) and a gadolinium precursor (gadolinium nitrate) into an aqueous solution under certain environmental conditions. At this time, the particle size (D ₅₀ ) of the carrier was 180 nm.

[Formula 1-1]

Gd _x Ce _1-x O _2-y

In Formula 1-1, x is 0.1, y is an oxygen vacancy value that makes the compound electrically neutral, and satisfies 0<y≤0.25.

Next, platinum in a precursor state is prepared, a support is mixed therein, and a process of inducing a reduction reaction from platinum in a precursor state to platinum metal in a nanoparticle state is performed using a reducing agent, so that platinum nanoparticles are formed as a support An integrated durability improver (Pt/GDC) was prepared by depositing on the surface.

The content of the platinum nanoparticles in the prepared durability improver was 0.10% by weight, and the average particle size (D ₅₀ ) of the platinum powder was about 17 nm.

(2) Preparation of electrolyte membrane forming solution

A perfluorine sulfonic acid-based ionomer (trade name: Aquivion ^® D72-25DS, Solvay) having an equivalent weight of -SO ₃ H group of 720 was prepared.

An electrolyte film forming solution was prepared by mixing 0.5 wt % of the high durability improver (Pt/GDC), 0.97 wt % of the radical scavenger (CeZnO), and the remaining amount of the ionomer.

Example 6-2

(1) Manufacture of durability improver

A durability improver was prepared in the same manner as in Example 1, but using GDC represented by Chemical Formula 1-2 as a carrier.

[Formula 1-2]

Gd _x Ce _1-x O _2-y

In Formula 1-2, x is 0.2, y is an oxygen vacancy value that makes the compound electrically neutral, and satisfies 0<y≤0.25.

(2) Preparation of electrolyte membrane forming solution

Using the same perfluorine sulfonic acid-based ionomer as in Example 1, 0.5 wt% of the durability improver (Pt/GDC) and the remaining amount of the ionomer were mixed to prepare an electrolyte membrane forming solution.

Comparative Examples 1-3 to 1-5

The high durability improver and the electrolyte membrane forming solution were prepared in the same manner as in Example 1-1, but the electrolyte membrane forming solution was varied in the particle size of platinum in the high durability improver, the particle size of the carrier, or the content of the high durability improver as shown in Table 1 below. were prepared respectively.

division high durability enhancer ionomer Pt particle size (D ₅₀ )/content Support particle size (D ₅₀ )/content type of carrier in an electrolyte forming solution
High durability enhancer content BET
specific surface area Example 1-1 5 nm / 0.1% by weight 177nm/ remaining amount CeO ₂ 0.5% by weight 150 m ² /g remain
balance
100% by weight Example 1-2 5nm/ 1.0wt% 177nm/ remaining amount CeO ₂ 0.5% by weight 147 m ² /g Examples 1-3 5 nm / 3.0% by weight 177nm/ remaining amount CeO ₂ 0.5% by weight 155 m ² /g Example 1-4 5 nm / 5.5% by weight 177nm/ remaining amount CeO ₂ 0.5% by weight 142 m ² /g Example 2-1 12nm/ 1.0wt% 242 nm/ remaining balance IrO ₂ 0.5% by weight 90 m ² /g Example 2-2 12 nm/ 0.1% by weight 242 nm/ remaining balance IrO ₂ 0.5% by weight 92 m ² /g Example 3-1 9 nm/ 1.0% by weight 353 nm/ remaining amount SnO ₂ 0.5% by weight 83 m ² /g Example 3-2 9 nm / 0.1% by weight 353 nm/ remaining amount SnO ₂ 0.5% by weight 77 m ² /g Example 4-1 7nm/ 1.0wt% 502nm/ remaining amount Ti ₄ O ₇ 0.5% by weight 50 m ² /g Example 4-2 7 nm / 0.1% by weight 502nm/ remaining amount Ti ₄ O ₇ 0.5% by weight 64 m ² /g Example 5 5nm/ 1.0wt% 177nm/ remaining amount CeO ₂ 17.0% by weight 151 m ² /g Example 6-1 17 nm / 0.1% by weight 180 nm/1.0% by weight GDC (Formula 1-1) 0.5% by weight 151 m ² /g Example
6-2 22 nm/ 0.1% by weight 223 nm/ 1.0% by weight GDC (Formula 1-2) 0.5% by weight 116 m ² /g Comparative Example 1-1 - 177nm/ remaining amount CeO ₂ 0.5% by weight 146 m ² /g Comparative Example 1-2 5nm/ 6.0wt% 177nm/ remaining amount CeO ₂ 0.5% by weight 132 m ² /g Comparative Example 1-3 63nm/ 1.0wt% 177 nm /1.0% by weight CeO ₂ 0.5% by weight 134 m ² /g Comparative Example 1-4 5nm/ 1.0wt% 2,025 nm/1.0% by weight CeO ₂ 0.5% by weight 56 m ² /g Comparative Example 1-5 5nm/ 1.0wt% 177nm/ remaining amount CeO ₂ 20.8% by weight 130 m ² /g

Experimental Example 1: Evaluation of durability of electrolyte membrane and analysis of fluorine ion release rate

In order to evaluate the durability of the electrolyte membrane, each of the electrolyte membrane forming solutions prepared in Examples and Comparative Examples was coated on the film, and then dried to prepare a single-layer electrolyte membrane having a thickness of 10 μm.

(1) Measurement of fluoride ion release rate (FER, umol/g h)

After preparing a Fenton solution by mixing iron sulfate lead hydrate and hydrogen peroxide, each of the electrolyte membranes prepared in Examples and Comparative Examples was added to the Fenton solution, and then left at 80 ° C. for 120 hours, and then the fluorine ion release rate was measured. . The electrolyte membrane is degraded by the radicals of the Fenton solution to release fluorine ions (F ^- ), and durability was evaluated by measuring the concentration of fluorine ions in the Fenton solution, and the results are shown in Table 2 below.

(2) Measurement of OCV (open cercit voltage) holding durability

After preparing a membrane-electrode assembly by attaching a catalyst and a gas diffusion layer (GDL) to each of the electrolyte membranes of Examples and Comparative Examples, open circuit voltage under harsher environmental conditions (90 ° C / 30% relative humidity) than actual cell operating conditions (OCV, open circuit voltage) was measured, and the results are shown in Table 2 below.

The control group in Table 2 below is an electrolyte membrane prepared without using a platinum catalyst or a carrier.

division Pt content
(weight%) type of carrier FER
(umol/g h) OCV
End Life Time (hr) Example 1-1 0.1 CeO ₂ 2.45 914 Example 1-2 1.0 CeO ₂ 0.64 1305 Example 1-3 3.0 CeO ₂ 0.78 1291 Example 1-4 5.5 CeO ₂ 1.05 1327 Example 2-1 1.0 IrO ₂ 1.15 1250 Example 2-2 0.1 IrO ₂ 2.81 851 Example 3-1 1.0 SnO ₂ 0.85 1286 Example 3-2 0.1 SnO ₂ 2.51 908 Example 4-1 1.0 Ti ₄ O ₇ 0.79 1288 Example 4-2 0.1 Ti ₄ O ₇ 2.55 921 Example 5 1.0 CeO ₂ 0.64 1144 Example 6-1 0.1 GDC
(Formula 1-1) 1.83 1027 Example 6-2 0.1 GDC
(Formula 1-2) 1.88 986 control group - - 15.10 318 Comparative Example 1-1 0 CeO ₂ 9.21 462 Comparative Example 1-2 6.0 CeO ₂ 1.13 1276 Comparative Example 1-3 1.0 CeO ₂ 3.41 683 Comparative Example 1-4 1.0 CeO ₂ 3.11 725 Comparative Example 1-5 1.0 CeO ₂ 0.72 1115

Looking at the measurement results of the fluorine ion release rate in Table 2, in the case of the electrolyte membrane (control group) to which Pt and the support were not applied, in the case of the electrolyte membrane of Comparative Example 1-1 to which only the support and the fluoride ion release rate of about 15.1 umol / gh were applied It showed a high fluorine ion release rate of about 9.21 umol/gh. In contrast, in the case of the electrolyte membranes of Examples 1-1 to 1-4 to which Pt/CeO ₂ was applied as a high durability enhancer, it was confirmed that they had a very low fluorine ion release rate (FER) of 3.50 umol/g h or less. And, as a support, IrO ₂ , Examples 2-1 to 2-2, Examples 3-1 to 3-2, Examples 4-1 to 4-2, and Examples 6-1 prepared using SnO ₂ , Ti ₄ O ₇ or GDC, respectively ~ 6-3 also showed an excellent FER reduction effect.

Overall _, the FER (Fluoride ion release rate) decreased as the platinum content in the high durability improver increased. In comparison, the results showed no increase in the effect of reducing FER.

In addition, looking at the OCV (open cercit voltage) holding durability measurement results in Table 2, it was confirmed that there was a difference in voltage drop between each Example and Comparative Example according to long-time operation.

And, in the case of Comparative Example 1-2, in which the Pt content in the high durability improver exceeded 5.5% by weight, compared to Examples 1-4, the FER value increased and the lifespan time was shortened, and the high durability improver In the case of Comparative Example 1-1 in which Pt was not used, there was a problem in that the FER value was high and the life time was greatly shortened.

In addition, in the case of Comparative Examples 1-3 in which the particle size of the platinum particles in the high durability improver exceeds 50 nm, the Pt specific surface area is reduced compared to the same Pt content and the particle size of the Pt particles and the support is similar to that of the support. There was a problem that Pt was aggregated with each other rather than Pt being located, reducing durability efficiency and lowering the electrochemical performance of the cell during long-term operation.

In addition, in the case of Comparative Examples 1-4 in which the average particle size of the carrier in the high durability improver exceeds 2,000 nm, the nano-sized Pt particles are not evenly dispersed due to the low specific surface area because the carrier particle size is large, reducing the Pt reaction characteristic efficiency. , Pt aggregation, etc., there was a problem of lowering durability and electrochemical performance.

In addition, in the case of Comparative Examples 1-5 in which the content of the high durability improver in the electrolyte forming solution was more than 20.0% by weight, there was no benefit due to the excessive use of the high durability improver.

Examples 2-3 to 2-4 and Comparative Examples 2-1 to 2-2

Using the same carrier as in Example 2-1, but varying the Pt particle content as shown in Table 3 below, to prepare a high durability improver (Pt/IrO ₂ ), and then use the same to prepare a high durability improver (Pt/IrO ₂ ) A solution for forming an electrolyte membrane was prepared by mixing 0.5% by weight and the remaining amount of the ionomer.

Experimental Example 2: Evaluation of durability of electrolyte membrane and analysis of fluorine ion release rate

Using the electrolyte membrane forming solutions prepared in Examples 2-3 to 2-4 and Comparative Examples 2-1 to 2-2, an electrolyte membrane having a single-layer structure having a thickness of 10 μm was prepared in the same manner as in Experimental Example 1, and then FER and OCV were measured, and the results are shown in Table 3 below.

division Pt content
(weight%) type of carrier FER
(umol/g h) OCV final life time (hr) Volate(V)
@1A/cm ² Example 2-1 1.0 IrO ₂ 1.15 1250 0.68 Example 2-2 0.1 IrO ₂ 2.81 851 0.70 Example 2-3 0.01 IrO ₂ 9.10 512 0.71 Example 2-4 4.5 IrO ₂ 0.88 1271 0.63 Comparative Example 2-1 0 IrO ₂ 10.27 353 0.72 Comparative Example 2-2 5.5 IrO ₂ 0.97 1288 0.59

Through Table 3, when IrO ₂ was applied as a support, it was confirmed that the appropriate content of Pt nanoparticles in the composite was 0.01 to 4.5% by weight.

Examples 3-3 to 3-4 and Comparative Examples 3-1 to 3-2

Using the same carrier as in Example 3-1, but varying the Pt particle content as shown in Table 4 below, to prepare a high durability improver (Pt/SnO ₂ ), and then use the same to prepare a high durability improver (Pt/SnO ₂ ) A solution for forming an electrolyte membrane was prepared by mixing 0.5% by weight and the remaining amount of the ionomer.

Experimental Example 3: Evaluation of durability of electrolyte membrane and analysis of fluorine ion release rate

Using the electrolyte membrane forming solutions prepared in Examples 3-3 to 3-4 and Comparative Examples 3-1 to 3-2, an electrolyte membrane having a single layer structure having a thickness of 10 μm was prepared in the same manner as in Experimental Example 1, and then, FER and OCV were measured, and the results are shown in Table 4 below.

division Pt content
(weight%) type of carrier FER
(umol/g h) OCV End Life Time (hr) Volate(V)
@1A/cm ² Example 3-1 1.0 SnO ₂ 0.85 1286 0.69 Example 3-2 0.1 SnO ₂ 2.51 908 0.71 Example 3-3 0.01 SnO ₂ 8.87 459 0.73 Example 3-4 3.0 SnO ₂ 0.79 1300 0.65 Comparative Example 3-1 0 SnO ₂ 9.54 411 0.73 Comparative Example 3-2 4.0 SnO ₂ 0.94 1185 0.61

Through Table 4, when SnO ₂ was applied as a support, it was confirmed that the appropriate content of Pt nanoparticles in the composite was 0.01 to 3.0% by weight.

Examples 4-3 to 4-4 and Comparative Examples 4-1 to 4-2

Using the same carrier as in Example 4-1, but varying the Pt particle content as shown in Table 4 below, to prepare a high durability improver (Pt/IrO ₂ ), and then use the same to prepare a high durability improver (Pt/Ti ₄ O ₇ ) 0.5% by weight and the remaining amount of the ionomer were mixed to prepare an electrolyte membrane forming solution.

Experimental Example 4: Evaluation of durability of electrolyte membrane and analysis of fluorine ion release rate

Using the electrolyte membrane forming solutions prepared in Examples 4-3 to 4-4 and Comparative Examples 4-1 to 4-2, an electrolyte membrane having a single-layer structure having a thickness of 10 μm was prepared in the same manner as in Experimental Example 1, and then, FER and OCV were measured, and the results are shown in Table 5 below.

division Pt content
(weight%) type of carrier FER
(umol/g h) OCV End Life Time (hr) Volate(V)
@1A/cm ² Example 4-1 1.0 Ti ₄ O ₇ 0.79 1288 0.70 Example 4-2 0.1 Ti ₄ O ₇ 2.55 921 0.73 Example 4-3 0.01 Ti ₄ O ₇ 8.50 561 0.74 Example 4-4 5.5 Ti ₄ O ₇ 0.69 1319 0.66 Comparative Example 4-1 0 Ti ₄ O ₇ 9.08 493 0.74 Comparative Example 4-2 6.5 Ti ₄ O ₇ 0.69 1320 0.61

Through the OCV final lifetime and Voltage performance values in Table 5, it was confirmed that the appropriate content of Pt nanoparticles in the composite was 0.01 to 5.50% by weight when Ti ₄ O ₇ was applied as a support.

Example 6-3 to Example 6-4 and Comparative Example 6-1 to Comparative Example 6-2

A high durability improver and an electrolyte membrane forming solution were prepared in the same manner as in Example 6-1, but the high durability improver was prepared by varying the Pt content as shown in Table 6, and then an electrolyte membrane forming solution was prepared using the same. .

Experimental Example 5: Evaluation of durability of electrolyte membrane and analysis of fluorine ion release rate

Using the electrolyte film forming solutions prepared in Examples 6-1, 6-3, 6-4, and Comparative Examples 6-1 to 6-2, a single-layer structure having a thickness of 10 μm was formed in the same manner as in Experimental Example 1. After each electrolyte membrane was prepared, FER and OCV were measured, and the results are shown in Table 6 below.

division Pt content
(weight%) type of carrier FER
(umol/gh) OCV End Life Time (hr) Example 6-1 0.1 GDC
(Formula 1-1) 1.83 1027 Example 6-3 3.0 2.21 652 Example 6-4 0.05 3.75 777 Comparative Example 6-1 5.5 2.39 624

Through the FER and OCV final life measurements in Table 6, GDC as a carrier Upon application, it was confirmed that the appropriate content of Pt nanoparticles in the composite was 0.01 to 5.00% by weight, preferably 0.01 to 3.00% by weight.

Example 7: Mixed type high durability improver

An electrolyte membrane forming solution was prepared by mixing the composite prepared in Example 1-1 and the composite prepared in Example 2-1 at a weight ratio of 1:0.3, 0.5% by weight of a high durability improver, and the remaining amount of the ionomer. .

Example 8: Mixed high durability improver

Electrolyte film forming solution by mixing the composite prepared in Example 1-1 and the Pt/GDC composite prepared in Example 6-1 at a weight ratio of 1:0.3, 0.5% by weight of a high durability enhancer, and the remaining amount of the ionomer. was manufactured.

Experimental Example 6: Evaluation of durability of electrolyte membrane and analysis of fluorine ion release rate

Using the electrolyte membrane forming solution prepared in Examples 7 to 8, an electrolyte membrane having a single-layer structure having a thickness of 10 μm was prepared in the same manner as in Experimental Example 1, and then FER and OCV were measured. The results are shown in Table 7 below. was

division Pt content
(weight%) type of carrier FER
(umol/g h) OCV
End Life Time (hr) Example 7 Pt/CeO ₂ composite : Pt/IrO ₂ composite = 1:0.3 weight ratio 0.66 1522 Example 8 Pt/CeO ₂ complex: Pt/GDC complex = 1:0.3 weight ratio 0.55 1443 Example 1-2 1.0 CeO ₂ 0.64 1305 Example 2-1 1.0 IrO ₂ 1.15 1250

Looking at Table 7, it was confirmed that as a high durability improver, Examples 7 and 8, in which two types of composites were used in combination, had a more excellent durability improvement effect than using only one type.

Preparation Example 1-1: Preparation of PTFE porous support

A paste was prepared by uniformly dispersing 23 parts by weight of liquid lubricant naphtha by mixing and stirring with 100 parts by weight of PTFE fine powder having an average particle diameter of 570 μm.

Next, the paste was left at 50° C. for 18 hours to mature, and then compressed using a molding jig to prepare a PTFE block.

Next, after putting the PTFE block into an extrusion mold, pressure extrusion was performed under a pressure of about 0.10 Ton/cm ² .

Next, it was rolled using a pressure roll to prepare an unsintered tape having an average thickness of 850 μm.

Next, the unsintered tape was dried by applying heat of 180° C. while being transferred to a conveyor belt at a speed of 3 M/min to remove the lubricant.

Next, the unsintered tape from which the lubricant was removed was uniaxially stretched (longitudinal stretching) by 6.5 times under conditions of a stretching temperature of 280° C. and a stretching speed of 10 M/min.

Next, the uniaxially stretched unsintered tape was biaxially stretched 30 times (width direction stretching) under conditions of a stretching temperature of 250° C. and a stretching speed of 10 M/min to prepare a porous support.

Next, the uniaxially and biaxially stretched porous supports were calcined on a conveyor belt at a rate of 15 M/min at 420° C. to prepare a PTFE porous support having an average thickness of 16 μm and an average pore size of 0.114 μm.

Preparation Example 1-2: Preparation of PTFE porous support

A porous PTFE support was prepared in the same manner as in Preparation Example 1-1. However, unlike Support Preparation Example 1-1, uniaxial and biaxial stretching conditions were changed to prepare a PTFE porous support having an average thickness of 5 μm and an average pore size of 0.114 μm.

Preparation Example 1-3: Preparation of PTFE porous support

A porous PTFE support was prepared in the same manner as in Preparation Example 1-1. However, unlike the support preparation example 1-1, uniaxial and biaxial stretching conditions were changed to prepare a porous PTFE support having an average thickness of 12 μm and an average pore size of 0.114 μm.

Preparation Example 1-4: Preparation of PTFE porous support

A porous PTFE support was prepared in the same manner as in Preparation Example 1-1. However, unlike the support preparation example 1-1, the uniaxial and biaxial stretching conditions were changed to prepare a porous PTFE support having an average thickness of 3 μm and an average pore size of 0.114 μm.

Preparation Example 2-1: Preparation of composite electrolyte membrane for PEMFC

(1) Preparation of a solution for forming an electrolyte membrane

0.5% by weight of the high durability enhancer (Pt/CeO ₂ ) prepared in Example 1-2 and 95.5% by weight of a perfluorinated sulfonated ionomer (solvay, aquivion D72-25DS) having an equivalent weight of -SO ₃ H group of 720 A solution for forming an electrolyte film was prepared by mixing %.

(2) The porous PTFE support prepared in Preparation Example 1-2 was prepared as a first support layer and a second support layer, respectively.

(3) After fixing the first support layer to a glass substrate, using a film applicator, one surface of the first support layer is impregnated with the solution for forming an electrolyte membrane, and then dried in a vacuum oven at 80 ° C for 20 minutes. Thus, a first electrolyte layer having an average thickness of 4 μm was formed on one surface of the first support layer.

(4) After fixing the second support layer to a glass substrate, using a film applicator to impregnate one surface of the second support layer with the solution for forming an electrolyte membrane, drying is performed in a vacuum oven at 80° C. for 20 minutes. Thus, a third electrolyte layer having an average thickness of 4 μm was formed on one surface of the second support layer.

(5) The other side of the first support layer having the first electrolyte layer formed on one side is impregnated with the solution for forming the electrolyte membrane, and then dried in a vacuum oven at 80° C. for 20 minutes to obtain an average thickness on the other side of the first support layer. A second electrolyte layer having a thickness of 3 μm was formed.

(6) The second support layer having the third electrolyte layer formed on one side is laminated on the other side of the prepared second electrolyte layer, and heat-treated at 160 ° C. for 10 minutes, such that the first electrolyte layer and the first support layer (= The average thickness of the second electrolyte layer, the second support layer (= thinning to an average thickness of 2 μm due to shrinkage due to manufacturing), and the third electrolyte layer are sequentially laminated to have an average thickness of 15 A composite electrolyte membrane for PEMFC having a thickness of ㎛ was prepared.

Preparation Example 2-2: Preparation of composite electrolyte membrane for PEMFC

(1) The porous PTFE support prepared in Support Preparation Example 1-1 was prepared as a first support layer and a second support layer, respectively.

(2) ~ (4) Using the PTFE porous support of Preparation Example 1-1 and the solution for forming an electrolyte membrane prepared in Preparation Example 2-1, the first electrolyte layer-first support layer-second electrolyte layer- A laminate in which the second support layer and the third electrolyte layer are stacked is prepared, but the first electrolyte layer (average thickness: 2.0 μm), the second electrolyte layer (average thickness: 1.0 μm), and the third electrolyte layer (average thickness: 2.0 μm) has formed

(5) Next, the laminate is heat-treated at 160 ° C. for 10 minutes to obtain a first electrolyte layer, a first support layer (= thinned to an average thickness of 5 μm due to manufacturing shrinkage), and a second electrolyte layer as shown in FIG. , A composite electrolyte membrane for PEMFC having an average thickness of 15 μm in which a second support layer (= thinned to an average thickness of 5 μm due to shrinkage in manufacturing) and a third electrolyte layer were sequentially stacked was prepared.

Preparation Example 2-3: Preparation of composite electrolyte membrane for PEMFC

(1) to (4) Using the same PTFE porous support as in Preparation Example 2-2 and the solution for forming an electrolyte membrane prepared in Preparation Example 2-1, the first electrolyte layer - the first support layer - the second electrolyte layer A laminate in which - the second support layer - the third electrolyte layer was stacked was prepared, and the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer were each formed to have an average thickness of 1 μm.

(5) Next, the laminate is heat-treated at 160 ° C. for 10 minutes to obtain a first electrolyte layer, a first support layer (= thinned to an average thickness of 5 μm due to manufacturing shrinkage), and a second electrolyte layer as shown in FIG. , A composite electrolyte membrane for PEMFC having an average thickness of 13 μm in which a second support layer (= thinned to an average thickness of 5 μm due to manufacturing shrinkage) and a third electrolyte layer were sequentially stacked was prepared.

Preparation Example 2-4: Preparation of composite electrolyte membrane for PEMFC

(1) The porous PTFE support prepared in Preparation Example 1-3 was prepared as a first support layer and a second support layer, respectively.

(2) to (4) Using the PTFE porous support of Preparation Example 1-3 and the solution for forming an electrolyte membrane prepared in Preparation Example 2-1, the first electrolyte layer-first support layer-second electrolyte layer- A laminate in which the second support layer and the third electrolyte layer are stacked is prepared, but the first electrolyte layer (average thickness 2.5 μm), the second electrolyte layer (average thickness 2.0 μm) and the third electrolyte layer (average thickness 2.5 μm) are prepared. has formed

(5) Next, the laminate is heat-treated at 160 ° C. for 10 minutes to obtain a first electrolyte layer, a first support layer (= thinned to an average thickness of 4 μm due to manufacturing shrinkage), and a second electrolyte layer as shown in FIG. , A composite electrolyte membrane for PEMFC having an average thickness of 15 μm in which a second support layer (= thinned to an average thickness of 4 μm due to shrinkage in manufacturing) and a third electrolyte layer were sequentially stacked was prepared.

Preparation Example 2-5: Preparation of composite electrolyte membrane for PEMFC

(1) The porous PTFE support prepared in Preparation Example 1-4 was prepared as a first support layer and a second support layer, respectively.

(2) to (4) Using the PTFE porous support of Preparation Example 1-4 and the solution for forming an electrolyte membrane prepared in Preparation Example 2-1, the first electrolyte layer-first support layer-second electrolyte layer- A laminate in which the second support layer and the third electrolyte layer are stacked is prepared, but the first electrolyte layer (average thickness 5.0 μm), the second electrolyte layer (average thickness 3.0 μm) and the third electrolyte layer (average thickness 5.0 μm) has formed

(5) Next, the laminate is heat treated at 160 ° C. for 10 minutes to obtain a first electrolyte layer, a first support layer (= thinned to an average thickness of 1 μm due to manufacturing shrinkage), and a second electrolyte layer as shown in FIG. , A composite electrolyte membrane for PEMFC having an average thickness of 15 μm in which a second support layer (= thinned to an average thickness of 1 μm due to shrinkage during manufacturing) and a third electrolyte layer were sequentially stacked was prepared.

Comparative Preparation Example 2-1: Preparation of composite electrolyte membrane for PEMFC

(1) Preparation of a solution for forming an electrolyte membrane

A solution for forming an electrolyte membrane without using a high durability enhancer was prepared by mixing 95.5% by weight of a perfluorine-based sulfonated ionomer (solvay, aquivion D72-25DS) having an equivalent weight of -SO ₃ H of 720.

(2) ~ (4) Using the PTFE porous support of Preparation Example 1-1 and the solution for forming an electrolyte membrane prepared in Preparation Example 2-1, the first electrolyte layer-first support layer-second electrolyte layer- A laminate in which the second support layer and the third electrolyte layer are stacked is prepared, but the first electrolyte layer (average thickness 4.0 μm), the second electrolyte layer (average thickness 3.0 μm) and the third electrolyte layer (average thickness 4.0 μm) are prepared. has formed

(5) Next, the laminate is heat-treated at 160 ° C. for 10 minutes to obtain a first electrolyte layer, a first support layer (= thinned to an average thickness of 5 μm due to manufacturing shrinkage), and a second electrolyte layer as shown in FIG. , A composite electrolyte membrane for PEMFC having an average thickness of 15 μm in which a second support layer (= thinned to an average thickness of 5 μm due to shrinkage in manufacturing) and a third electrolyte layer were sequentially stacked was prepared.

Experimental Example 7: Measurement of Physical Properties of Composite Electrolyte Membrane for PEMFC

(1) Durability test (Fenton test)

Each of the composite electrolyte membranes for PEMFCs prepared in Preparation Examples 2-1 to 2-5 and Comparative Preparation Example 2-1 was prepared with a size of 5 cm × 5 cm (width × length), and in an oven at 80 ° C. for 5 hours. After over-drying, the mass is measured. The prepared test piece was immersed in 200 g of a solution prepared by adding Fe ²⁺ 3 pm to hydrogen peroxide at a concentration of 2% by volume, and then left at 80° C. for 120 hours.

The fluorine ion concentration eluted from the test piece was measured using a fluorine ion selective electrode, and the results are shown in Table 3 below. In the Fenton test, the lower the measured value, the lower the fluorine ion elution, that is, the better the durability of the electrolyte membrane.

(2) Dimensional stability measurement experiment

Each of the composite electrolyte membranes for PEMFC prepared in Preparation Examples 2-1 to 2-5 and Comparative Preparation Example 2-1 was cut into 5 cm × 1 cm (MD direction × TD direction), and each of the cut composite electrolyte membranes for PEMFC The dimensional change rates in the MD direction (= length direction) and the TD direction (= width direction) were respectively measured by the following relational expression 1, and the results are shown in Table 8 below.

[Relationship 1]

In Equation 1, A represents the initial length of the composite electrolyte membrane for PEMFC, and B represents the length measured after leaving the composite electrolyte membrane for PEMFC at a temperature of 80 ° C. for 20 minutes.

In the dimensional change rate experiment, the lower the measured value, the higher the dimensional stability, that is, the better the mechanical properties of the electrolyte membrane.

(3) Performance measurement experiment

Each of the composite electrolyte membranes for PEMFC prepared in Preparation Examples 2-1 to 2-5 and Comparative Preparation Example 2-1 was cut into 8 cm × 8 cm (MD direction × TD direction), and each of the cut composite electrolyte membranes for PEMFC A membrane-electrode assembly for PEMFC as shown in FIG. 2 including a was prepared. Thereafter, the performance was calculated by measuring the voltage (V) measured at a current of 1A under conditions of a temperature of 65 ° C and an RH of 100%, and the results are shown in Table 3 below.

(4) Tensile strength measurement experiment

The tensile strength of each of the composite electrolyte membranes for PEMFC prepared in Preparation Examples 2-1 to 2-5 and Comparative Preparation Example 2-1 according to ASTM D882 was measured, and the results are shown in Table 8 below.

division manufacturing example
2-1 manufacturing example
2-2 manufacturing example
2-3 manufacturing example
2-4 manufacturing example
2-5 Comparative Manufacturing Example 2-1 1st electrolyte layer thickness
(μm) 4 2 One 2.5 5 4 1st support layer thickness
(μm) 2 5 5 4 One 2 2nd electrolyte layer Thickness (㎛) 3 One One 2 3 3 Second support layer Thickness (㎛) 2 5 5 4 One 2 3rd electrolyte layer thickness
(μm) 4 2 One 2.5 5 4 composite electrolyte membrane Overall thickness (㎛) 15 15 13 15 15 15 Performance (V/1A@65℃) 0.70 0.64 0.60 0.62 0.70 0.66 Durability (umol/gh) 1.65 1.76 1.73 1.77 1.70 13.8 Dimensional expansion rate
(%) MD direction One One One One 3 One TD direction 5 5 5 5 8 5 tensile strength
(Mpa) MD direction 64 68 69 65 49 63 TD direction 61 64 62 59 43 61

As can be seen in Table 8, it was confirmed that the composite electrolyte membranes for PEMFC prepared in Preparation Examples 2-1 to 2-5 had excellent durability and dimensional stability, as well as high tensile strength and excellent performance. In addition, when compared with Comparative Preparation Example 2-1, Preparation Examples 2-1 to 2-5 including the high durability improver in the electrolyte layer were confirmed to have relatively specialized characteristics in durability.

Preparation Example 3-1: Preparation of composite electrolyte membrane for PEMFC

The first electrolyte layer (4 μm), the first support layer (2 μm), the second electrolyte layer (3 μm), the second support layer (2 μm), and the third layer have the same thickness as those of Preparation Example 2-1. A laminate in which an electrolyte layer (4 μm) was stacked was prepared, but the porous PTFE support prepared in Preparation Example 1-2 was used as the first and second support layers.

As shown in Table 4 below, solutions for forming an electrolyte membrane having different contents of the high durability enhancer of Example 1 were prepared, and then the first to third electrolyte layers were formed using the solutions, respectively, to prepare a composite electrolyte membrane.

Comparative Preparation Example 3-1

First electrolyte layer (4 μm) - first support layer (2 μm) - second electrolyte layer (3 μm) - second support layer using the same support and forming an electrolyte layer having the same thickness as in Preparation Example 3-1 A laminate in which (2 μm)-third electrolyte layer (4 μm) is stacked is prepared, but the content of the high durability improver in the solution for forming the electrolyte film is varied, and then, as shown in Table 9 below, the high durability improver in the electrolyte layer A composite electrolyte membrane was prepared by varying the content, and Comparative Preparation Example 3-1 was performed.

Experimental Example 8: Measurement of Physical Properties of Composite Electrolyte Membrane for PEMFC

As shown schematically in A of FIG. 5, a PEMFC membrane having an anode electrode 200 having an anode catalyst layer 1, a composite electrolyte membrane 100, and a cathode electrode 300 having a cathode catalyst layer 2 - An electrode assembly was prepared.

At this time, the composite electrolyte 100 uses each of the composite electrolyte films of Preparation Example 3-1 and Comparative Preparation Example 3-1, wherein each first electrolyte layer is provided in the anode direction and the third electrolyte layer is provided in the cathode direction. made it so

In addition, the performance and durability measurement results according to the added content of the high durability improver and the application design in the manufactured membrane-electrode assembly are shown in Table 9 below.

division manufacturing example
3-1 Comparative Manufacturing Example
3-1 High durability improver content (% by weight) in the first electrolyte layer 0.5 1.5 High durability improver content in the second electrolyte layer (% by weight) 1.0 1.0 High durability improver content in the third electrolyte layer (% by weight) 1.5 0.5 Performance (V/1A@65℃) 0.70 0.67 Durability (umol/g h) 1.28 1.20

Comparing Preparation Example 3-1 and Comparative Preparation Example 3-1 of Table 8 above, as the content of the high durability enhancer increases in the cathode direction rather than the anode direction in each layer of the first to third electrolyte layers constituting the composite electrolyte ( 1st electrolyte layer < 2nd electrolyte layer < 3rd electrolyte layer) The durability improvement effect was relatively more excellent, and the performance was also advantageous.

Preparation Example 4-1: Preparation of membrane-electrode assembly for PEMFC

The same composite electrolyte membrane for PEMFC as in Preparation Example 3-1 was prepared.

Next, as an oxidation catalyst of the anode catalyst layer and a reduction catalyst of the cathode catalyst layer, a Pt-C catalyst having a supported Pt content of 57.7% by weight in carbon black (C) as a support was prepared.

In addition, an anode electrode (thickness of 15 μm) composed of an anode catalyst layer containing 10% by weight of the Pt—C catalyst and 18% by weight of the ionomer was formed on one side of the composite electrolyte membrane for the PEMFC.

In addition, a cathode electrode (thickness of 15 μm) composed of a cathode catalyst layer containing 10% by weight of the Pt-C catalyst and 18% by weight of the ionomer is formed on the other surface of the composite electrolyte membrane for PEMFC on which the anode electrode is formed, thereby forming a membrane-electrode assembly for PEMFC. manufactured.

The platinum (Pt) content derived from Pt-C in the anode electrode and the cathode electrode is shown in Table 10, and the average value of the platinum content derived from the high durability improver in the first electrolyte layer and the second electrolyte layer of the composite electrolyte membrane is shown in Table 10 below. shown in

Preparation Examples 4-2 to 4-3 and Comparative Examples 4-1 to 4-2

A membrane-electrode assembly for PEMFC was prepared in the same manner as in Preparation Example 4-1, but the Pt-C catalyst content in the anode catalyst layer and cathode electrode layer was adjusted, and the high durability improver (Pt/ By adjusting the content of CeO ₂ ), as shown in Table 10 below, membrane-electrode assemblies for PEMFCs having different Pt contents in the anode electrode, the cathode electrode, and the composite electrolyte membrane were prepared, respectively, in Preparation Examples 4-2 to 4-3 and Comparative Preparation Examples 4-1 to 4-2 were carried out, respectively.

Experimental Example 9: Measurement of physical properties of membrane-electrode assembly for PEMFC

The Pt content in the prepared membrane-electrode assembly was expressed as the weight of platinum per unit area (mg/cm ² ) of the anode electrode (catalyst layer), cathode electrode (catalyst layer) and electrolyte layer of the composite electrolyte membrane, and the performance and durability measurement results are shown below. Table 10 shows.

division Pt content in MEA (mg/cm ² ) electrochemical performance anode
electrode complex
electrolyte membrane cathode
electrode Volate(V)
@1A/cm ² OCV
End Life Time (hr) Comparative Preparation Example 4-1 0.40 0 0.40 0.682 1087 Comparative Preparation Example 4-2 0.30 0 0.40 0.665 1025 Comparative Preparation Example 4-3 0.40 0.10 0.40 0.659 1125 Comparative Preparation Example 4-4 0.45 0.05 0.35 0.668 1229 Preparation Example 4-1 0.40 0.05 0.40 0.670 1561 Preparation Example 4-2 0.40 0.02 0.40 0.681 1238 Preparation Example 4-3 0.35 0.05 0.45 0.685 1774

Looking at Table 10, comparing Preparation Examples 4-1 to 4-3 and Comparative Preparation Examples 4-1 to 4-2, the OCV of the MEA containing platinum is higher than that of the case without platinum in the composite electrolyte membrane. showed a tendency to

And, in the case of Comparative Preparation Example 4-3 in which the Pt content in the composite electrolyte membrane exceeded 0.08 mg/cm ² , compared to Preparation Example 4-1, the electrochemical performance was rather poor.

And, in the case of Comparative Preparation Example 4-4, in which the Pt content in the anode electrode is relatively higher than that in the cathode electrode, compared to Preparation Examples 4-1 to 4-3, the electrochemical performance is rather poor.

In particular, in the case of Preparation Example 4-3, in which the amount of Pt t in the cathode electrode is higher than that in the anode electrode, compared to Preparation Example 4-1, the effect of reducing gas permeation by platinum is increased and the final OCV life time is significantly increased. .

And, in the case of Comparative Preparation Example 4-4, in which the anode electrode had a higher platinum content than the cathode electrode, the electrochemical performance was unfavorable compared to Preparation Examples 4-1 to 4-3.

Through this, it was confirmed that in view of the durability of the MEA, it is structurally advantageous that the anode electrode and the cathode electrode have the same Pt content or, preferably, the cathode electrode has a high Pt content.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments can be easily proposed by means of changes, deletions, additions, etc., but these will also fall within the scope of the present invention.

Reference Numerals 1: anode catalyst layer 2: cathode catalyst layer
3,3': gas diffusion layer
11: first support layer, support layer 12: second support layer
13: third support layer 14: fourth support layer
21: first electrolyte layer 22: second electrolyte layer
23: third electrolyte layer 24: fourth electrolyte layer
25: fifth electrolyte layer 100: composite electrolyte membrane for PEMFC
200: anode 300: cathode

Claims (13)

An anode electrode including an anode catalyst layer;
Composite electrolyte membrane for PEMFC (Polymer Electrolyte Membrane Fuel Cell); and
A cathode electrode including a cathode catalyst layer; includes,
The composite electrolyte membrane includes an electrolyte layer and a support layer containing a high durability improver,
The high durability enhancer includes a composite including platinum (Pt) particles having a particle size (D ₅₀ ) of 1.0 to 50.0 nm and a carrier carrying the platinum particles,
The anode catalyst layer and the cathode catalyst layer include a Pt-C (platinum-carbon) catalyst,
A membrane-electrode assembly for PEMFC, characterized in that the anode electrode, the composite electrolyte membrane and the cathode electrode satisfy Equation 1 below;
[Equation 1]
B < A ≤ C
In Equation 1, A means the weight per unit area (mg/cm ² ) of platinum (Pt) derived from the Pt-C catalyst in the anode catalyst layer, and B is platinum derived from the high durability improver in the electrolyte layer of the composite electrolyte membrane ( Pt) means the weight per unit area (mg/cm ² ), and C means the weight per unit area (mg/cm ² ) of platinum (Pt) derived from the Pt—C catalyst in the cathode catalyst layer.
The method of claim 1, wherein the composite electrolyte membrane for the PEMFC,
A membrane-electrode assembly for PEMFC, characterized in that the content of the high durability improver in the electrolyte layer increases in the direction from the anode electrode to the cathode electrode.
The method of claim 1, wherein the composite electrolyte membrane for the PEMFC is a composite electrolyte membrane in which a first electrolyte layer, a first support layer and a second electrolyte layer are sequentially stacked,
A membrane-electrode assembly for a PEMFC, characterized in that at least one layer selected from the first electrolyte layer and the second electrolyte layer includes the high durability improver and the ionomer.
The method of claim 3, wherein the first electrolyte layer is an electrolyte layer in the direction of the anode electrode, the second electrolyte layer is an electrolyte layer in the direction of the cathode electrode,
The first electrolyte layer and the second electrolyte layer include the high durability improver,
The high durability improver content in the first electrolyte layer and the high durability improver content in the second electrolyte layer are 0.1 to 0.9: 1 membrane-electrode assembly for PEMFC, characterized in that the weight ratio.
The membrane-electrode assembly for PEMFC according to claim 3, wherein at least one selected from among the first electrolyte layer and the second electrolyte layer further comprises a cerium (Ce)-based radical scavenger.
According to claim 1, wherein the composite electrolyte membrane for the PEMFC is a composite in which a first electrolyte layer, a first support layer, a second electrolyte layer, a second support layer, and a third electrolyte layer are sequentially stacked in a direction from the anode electrode to the cathode electrode. electrolyte membrane; or
A composite electrolyte membrane in which a first electrolyte layer, a first support layer, a second electrolyte layer, a second support layer, a third electrolyte layer, a third support layer, and a fourth electrolyte layer are sequentially stacked;
Each of the first electrolyte layer, the second electrolyte layer, the third electrolyte layer, and the fourth electrolyte layer independently includes the high durability improver, but the content of the high durability improver in the electrolyte layer increases in the direction from the anode electrode to the cathode electrode. A membrane-electrode assembly for PEMFC, characterized in that it has a gradient.
The membrane-electrode assembly for PEMFC according to claim 1, wherein the anode electrode and the cathode electrode further include a gas diffusion layer in the direction of the other surface of the surface on which the composite electrolyte membrane is laminated.
The membrane-electrode assembly for PEMFC according to claim 1, wherein the average thickness of the composite electrolyte membrane for PEMFC is 5 to 30 μm.
The method of claim 1, wherein the high durability enhancer comprises 0.01 to 6.00 wt% of platinum (Pt) particles having a particle size (D ₅₀ ) of 0.1 to 50.0 nm and a carrier carrying the platinum particles as the remainder of the total wt%, ,
The platinum particles are bonded to and integrated with the surface of the carrier,
The carrier includes at least one selected from CeO ₂ , Gd doped Ceria (GDC), IrO ₂ , SnO ₂ and Ti ₄ O ₇ ,
The GDC is a film-electrode assembly for a PEMFC, characterized in that gadolinium (Gd) is doped in a ceria lattice, represented by Formula 1 below.
[Formula 1]
Gd _x Ce _1-x O _2-y
In Formula 1, x satisfies 0<x≤0.3, y is an oxygen vacancy value that makes the compound electrically neutral, and satisfies 0<y≤0.25.
delete 10. The membrane-electrode assembly for PEMFC according to claim 9, wherein the carrier has a particle size (D ₅₀ ) of 10 to 2,000 nm.
The method of claim 9, wherein the high durability improver,
When the support is CeO ₂ , it contains 0.01 to 6.00% by weight of platinum particles based on the total weight of the high durability improver,
When the support is GDC, it contains 0.01 to 5.00% by weight of platinum particles based on the total weight of the high durability improver,
When the support is IrO ₂ , it includes 0.01 to 4.50 wt% of platinum particles based on the total weight of the high durability improver,
When the support is SnO ₂ , it contains 0.01 to 3.00 wt% of platinum particles based on the total weight of the high durability improver,
When the support is Ti ₄ O ₇ , a membrane-electrode assembly for PEMFC, characterized in that it contains 0.01 to 5.50% by weight of platinum particles based on the total weight of the high durability improver.
A polymer electrolyte fuel cell comprising the membrane-electrode assembly of any one of claims 1 to 9, 11 and 12.

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