KR102469429B1 - High durable enhancer for electrolyte membrane of PEMFC, Electrolyte membrane for PEMFC containing the same, and membrane electrode assembly containing the same - Google Patents

Abstract

The present invention relates to a high durability enhancer for a PEMFC, a composite electrolyte membrane for a PEMFC manufactured using the same, and a membrane-electrode assembly and, specifically, to a composite electrolyte membrane for a PEMFC and a membrane-electrode assembly, wherein when a PEMFC electrolyte membrane is thinned, the durability of the electrolyte membrane is reduced due to deterioration, and the durability enhancer of the present invention suppresses the deterioration of the electrolyte membrane, thereby preventing degradation of durability of the electrolyte membrane due to deterioration and providing high dimensional stability, mechanical properties, and electrical stability.

Description

High durable enhancer for electrolyte membrane of PEMFC, Electrolyte membrane for PEMFC containing the same, and membrane electrode assembly containing the same}

The present invention relates to a high durability enhancer that suppresses chemical degradation of an electrolyte membrane of a membrane-electrode assembly for PEMFC, an electrolyte membrane for PEMFC manufactured by applying the same, a composite electrolyte membrane for PEMFC having a multi-layer structure, and a membrane-electrode assembly .

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)

The present invention was devised in view of the above points, and has high durability for PEMFC electrolyte membranes that can compensate for the insufficient secondary antioxidant effect of Ce-based radical antioxidants used as primary antioxidants used in manufacturing PEMFC electrolyte membranes. An enhancer has been developed, and it is applied to a thinned electrolyte membrane at an optimal ratio, and an electrolyte membrane for PEMFC in which the electrolyte membrane is compounded in a single or multilayer structure and a membrane-electrode assembly for PEMFC using the same are provided.

The present invention for solving the above problems relates to a durability improver for a PEMFC electrolyte membrane, wherein the durability improver of the present invention includes a compound represented by the following Chemical Formula 1, wherein the compound is gadolinium (Gd) doped in a ceria lattice it is a compound

[Formula 1]

Gd _x Ce _1-x O _2-y

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

As a preferred embodiment of the present invention, the particle size (D ₅₀ ) of the durability improver may be 100 to 1,000 nm.

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

Another object of the present invention is to provide an electrolyte membrane for a PEMFC including a durability improver, a cerium (Ce)-based radical scavenger, and an ionomer in an electrolyte membrane including a cerium (Ce)-based radical scavenger.

As a preferred embodiment of the present invention, the cerium (Ce)-based radical scavenger is CeZnO, CeO ₂ , CePO ₄ , CeF 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 ) ₃ · 3H ₂ It may include one or more selected from O.

As a preferred embodiment of the present invention, the electrolyte membrane for the PEMFC is a radical containing one or more selected from Ru, Ag, RuO ₂ , WO ₃ , Fe ₃ O ₄ , CrPO ₄ , AlPO ₄ , FePO ₄ and FeF ₃ A cabiner may be further included.

As a preferred embodiment of the present invention, the electrolyte membrane for a PEMFC of the present invention may further include at least one selected from hollow silica and a moisture absorbent.

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

As a preferred embodiment of the present invention, the electrolyte membrane for PEMFC may be a composite electrolyte membrane.

As a preferred embodiment of the present invention, the composite electrolyte membrane has a structure in which a first electrolyte layer, a first support layer, and a second electrolyte layer are sequentially stacked, and at least one layer of the first electrolyte layer and/or the second electrolyte layer may include the aforementioned durability improver.

As a preferred embodiment of the present invention, the composite electrolyte membrane having a structure in which a first electrolyte layer, a first support layer, and a second electrolyte layer are stacked may satisfy the following condition (1).

Condition (1) B ₁ ≤ A ₁ , B ₁ ≤ A ₂

In condition (1), 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.

As a preferred embodiment of the present invention, in the composite electrolyte membrane for PEMFC, when a membrane-electrode assembly for PEMFC is applied, an electrolyte layer, a first support layer, and a second electrolyte layer are sequentially stacked in an anode direction in a cathode direction. It is a composite electrolyte membrane, and the composite electrolyte membrane for the PEMFC may satisfy the following condition (2).

Condition (2) A ₁ ≤ A ₂

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

As a preferred embodiment of the present invention, the composite electrolyte membrane may have a multilayer structure 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, and the At least one layer selected from among the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer may include the durability improver described above.

As a preferred embodiment of the present invention, the third support layer formed on one surface of the third electrolyte layer; and a fourth electrolyte layer formed on one side of the third support layer. may further include.

As a preferred embodiment of the present invention, the third electrolyte layer may include the durability improver described above.

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

As a preferred embodiment of the present invention, the composite electrolyte membrane for the PEMFC may satisfy both the following conditions (3) and (4).

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

Condition (4) B ₂ ≤ A ₁ , B ₂ ≤ A ₂ , B ₂ ≤ A ₃

In conditions (3) and/or (4), A ₁ is the thickness of the first electrolyte layer, A ₂ is the thickness of the second electrolyte layer, A ₃ is the thickness of the third electrolyte layer, and B ₁ is the first support represents the thickness of the layer, and B ₂ represents the thickness of the second support layer.

As a preferred embodiment of the present invention, the composite electrolyte membrane for PEMFC is a first electrolyte layer, a first support layer, a second electrolyte layer, a second support layer and It is a composite electrolyte membrane in which the third electrolyte layers are sequentially stacked, and the following condition (5) or condition (6) may be satisfied.

Condition (5) A ₁ ≤ A ₂ ≤ A ₃

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

In the above conditions (5) and (6), A ₁ is the content of the durability improver in the first electrolyte layer, A ₂ is the content of the durability improver in the second electrolyte layer, and A ₃ is the content of the durability improver in the third electrolyte layer indicates

In a preferred embodiment of the present invention, the composite electrolyte membrane for a PEMFC of the present invention may satisfy the following condition (3).

≤ 12Condition (3) 1.5 ≤

≤ 12

In condition (3), A ₁ is the thickness of the first electrolyte layer, A ₂ is the thickness of the second electrolyte layer, A ₃ is the thickness of the third electrolyte layer, B ₁ is the thickness of the first support layer, B ₂ represents the thickness of the second support layer.

In a preferred embodiment of the present invention, the composite electrolyte membrane for a PEMFC of the present invention may satisfy the following condition (4).

≤ 10Condition (4) 0.2 ≤

≤ 10

In condition (4), A ₁ represents the thickness of the first electrolyte layer, A ₂ represents the thickness of the second electrolyte layer, and A ₃ represents the thickness of the third electrolyte layer.

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 has an equivalent weight (EW) of 1,100 or less of the -SO ₃ H group. can

Another object of the present invention relates to a membrane-electrode assembly for a PEMFC, comprising: an anode (oxidation electrode); The electrolyte membrane for the PEMFC or the composite electrolyte membrane for the PEMFC; and cathode (reduction electrode); can include

The composite electrolyte membrane for PEMFC prepared by introducing the durability enhancer of the present invention compensates for the insufficient secondary oxidation prevention effect of the Ce-based radical scavenger and has a thin thickness, excellent durability and dimensional stability, and high tensile strength. high efficiency and excellent performance, it is possible to manufacture a membrane-electrode assembly for PEMFC with excellent long-term stability and high efficiency, and a fuel cell incorporating the same.

1a and 1b are schematic diagrams of a composite electrolyte membrane for a PEMFC having a multi-layer structure 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 membrane-electrode assembly for a PEMFC according to a preferred embodiment of the present invention.
5a and 5b are graphs of durability and OCV measurement results of Examples and Comparative Examples conducted in Experimental Example 1;

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.

The durability improver for the PEMFC electrolyte membrane of the present invention prevents the electrolyte membrane from deteriorating due to radicals generated during PEMFC operation, and supplements the insufficient secondary antioxidant effect of the Ce-based radical scavenger, that is, decomposes hydrogen peroxide, It serves to increase durability of the electrolyte membrane by performing gas decomposition and/or gas barrier function and electron conductor function.

The durability improver of the present invention is in powder form and includes a compound represented by Formula 1 below, and is a compound doped with gadolinium (Gd) in a ceria lattice (Gd-doped Ceria, hereinafter referred to as “GDC”).

[Formula 1]

Gd _x Ce _1-x O _2-y

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

In addition, the particle size (D ₅₀ ) of the GDC may be 50 to 1,000 nm, preferably 100 to 500 nm, and more preferably 100 to 450 nm. At this time, if the particle size (D ₅₀ ) of GDC is 100 nm or less, problems due to particle aggregation may occur, and if the particle size (D ₅₀ ) of GDC exceeds 1,000 nm, the reaction area is reduced, and the secondary antioxidant effect is poor. There may be a problem.

The durability improver of the present invention may have a BET specific surface area of 10 to 500 m ² /g, preferably 80 to 500 m ² /g, and more preferably 90 to 300 m ² /g.

The GDC can be synthesized by a method in which gadolinium oxide and cerium oxide are pulverized and mixed and synthesized using a solid phase reaction (solid solution) at a high temperature, and a method in which a mixed solution of a cerium precursor and a gadolinium precursor is added dropwise to an aqueous solution to obtain a coprecipitate.

The gadolinium precursor is gadolinium nitrate, gadolinium bromide, gadolinium bromate, gadolinium selenite, gadolinium selenide, gadolinium iodate , gadolinium fluoride, gadolinium phosphate, gadolinium sulfate, gadolinium chloride, gadolinium acetate, gadolinium perchlorate, gadolinium oxalate (gadolinium oxalate), gadolinium oxychloride, and gadolinium ethylsulfate.

The cerium precursor is cerium nitrate, cerium bromide, cerium bromate, cerium selenite, cerium selenide, cerium iodate , cerium fluoride, cerium phosphate, cerium sulfate, cerium chloride, cerium acetate, cerium perchlorate, cerium oxalate (cerium oxalate), cerium oxychloride, and cerium ethylsulfate.

Hereinafter, an electrolyte membrane for a PEMFC using the durability improver of the present invention described above will be described.

The electrolyte membrane for the PEMFC may be prepared using an electrolyte membrane (or electrolyte layer) forming solution containing a durability improver, a cerium (Ce)-based radical scavenger, and an ionomer.

The electrolyte membrane forming solution may include 0.01 to 10 wt% of the durability improver, preferably 0.05 to 5.0 wt%, and more preferably 0.1 to 2.0 wt% of the durability improver, based on the total weight of the electrolyte film forming solution. At this time, if the content of the durability improver is less than 0.01% by weight, the amount used is too small and there may be no effect of preventing deterioration of the electrolyte layer (or electrolyte membrane). It is good to use it within the above range because a problem of lowering may occur.

In addition, the amount of the cerium-based radical scavenger in the electrolyte membrane forming solution preferably includes the durability improver and the cerium-based radical scavenger in a weight ratio of 1:0.2 to 5.0, preferably 1:0.30 to 3.50 A weight ratio, more preferably 1: 0.50 to 3.00 weight ratio is advantageous in terms of primary and secondary antioxidant effects.

The Ce-based radical scavenger may use a Ce-based radical scavenger used in an electrolyte membrane in the art, and preferably CeZnO, CeO ₂ , CePO ₄ , CeF 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 ) ₃ · 3H ₂ O may include at least one selected from.

In addition, the cerium-based radical scavenger may be 500 nm or less, preferably 300 nm or less, and more preferably 100 to 300 nm when the particle size (D50) is analyzed with a DLS (Dynamic Light Scattering) type nano particle size analyzer. .

In addition, the cerium-based radical scavenger mixes a Ce precursor aqueous solution with a [Zn(OH) ₄ ] ^2- containing solution and performs a reduction reaction to form CeZnO metal oxide particles having a ZnO crystal structure doped with cerium ions, can be manufactured 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.

The cerium-based radical scavenger thus prepared is a metal oxide particle having a crystal structure composed of cerium (Ce) atoms, zinc (Zn) atoms, and oxygen (O) atoms. In the ZnO crystal structure having a crystal structure, some of the Zn atoms may have a crystal structure in which Ce atoms are substituted, and the cerium-based radical scavenger contains 12 to 91% by weight of Ce, 7 to 84.5% by weight of Zn, and the balance. of O (oxygen atom), preferably 13.40 to 89.20% by weight of Ce, 7.55 to 88.20% by weight of Zn, and the balance of O. And, it may further contain other unavoidable impurities.

In addition, the electrolyte membrane for the PEMFC is a radical scavenger containing at least one selected from Ru, Ag, RuO ₂ , WO ₃ , Fe ₃ O ₄ , CrPO ₄ , AlPO ₄ , FePO ₄ and FeF ₃ in addition to a Ce-based radical scavenger. A cabiner may be further included.

The ionomer may include an ionomer including at least one selected from a perfluorine-based sulfonated ionomer (PFSA ionomer) and a hydrocarbon-based ionomer.

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 electrolyte membrane for a PEMFC of the present invention may further include at least one selected from hollow silica and a moisture absorbent.

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, the moisture absorbent may include at least one selected from zeolite, titania, zirconia, and montmorillonite.

The electrolyte membrane for a PEMFC of the present invention may have a single layer structure or a multilayer structure, and an example of the multilayer structure may be a composite electrolyte membrane as follows. 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 durability improver described above.

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 durability improver may be included in the electrolyte layer to satisfy 2), and the role and effect of the durability improver are greater at the cathode than at the anode of the PEMFC membrane-electrode assembly when the following condition (2) is satisfied. Satisfying the following condition (2) is advantageous in terms of performance and durability of the PEMFC membrane-electrode assembly.

Condition (2) A ₁ ≤ A ₂

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

In addition, referring to FIG. 1B, 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, and a third The 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.

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 (5) or condition (6), and satisfying the following condition (5) or (6) is advantageous in terms of optimizing the durability improver effect of the PEMFC membrane-electrode assembly.

Condition (5) A ₁ ≤ A ₂ ≤ A ₃

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

In the above conditions (5) and (6), A ₁ is the content of the durability improver in the first electrolyte layer, A ₂ is the content of the durability improver in the second electrolyte layer, and A ₃ is the content of the durability improver in the third electrolyte layer indicates

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.

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.

Next, the aging of step 1-2 is a preforming process, and the paste may be aged for 12 to 24 hours at a temperature of 30 ° C to 70 ° C, preferably at a temperature of 35 ° C to 60 ° C. It can mature for 20 hours. 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 carried out 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) of 1:3.00 to 8.5, preferably 1 in the uniaxial direction (longitudinal direction) and biaxial direction (width direction). : 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% 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 impregnated with an electrolyte to prepare an electrolyte membrane using the PTFE porous support, 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 1 below for uniaxial modulus and biaxial modulus values.

[Equation 1]

0 ≤ │(uniaxial modulus−biaxial modulus)/(uniaxial modulus)×100%│≤54%, preferably 0 ≤│(uniaxial modulus−biaxial modulus)/(uniaxial) directional 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 composite electrolyte membrane of the present invention has a thickness of 0.1 to 10 μm, preferably a thickness of 1 to 7 μm, and more preferably a thickness of 1 to 5 μm. It may have a thickness of 1.5 to 4 μm, more preferably 1.5 to 2.5 μm, and if the thickness is less than 0.1 μm, there may be a problem in that the tensile strength decreases, and 10 μm If it exceeds, there may be a disadvantageous problem in thinning.

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 composite electrolyte membrane of the present invention has a thickness of 1 to 10 μm, preferably It may have a thickness of 1 to 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, , if it exceeds 10 μm, 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 has an equivalent weight of -SO ₃ H group (EW) 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 exceeds 1,100 Doing so may cause performance degradation.

The composite electrolyte membrane for PEMFC of the present invention has a dimensional change rate of 10% or less, preferably 0 to 5%, more preferably 0 to 3%, and even more preferably, in the MD direction (= longitudinal direction) measured by the following relational expression 1 may be 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 to 7%, still more preferably It may be 4 to 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 PEMFC of the present invention 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 has excellent durability and dimensional stability, as well as high tensile strength and excellent performance.

In addition, the composite electrolyte membrane for a PEMFC of the present invention may satisfy the following condition (1) when the first electrolyte layer, the first support layer, and the second electrolyte layer are sequentially stacked electrolyte membranes.

Condition (1) B ₁ ≤ A ₁ , B ₁ ≤ A ₂

In condition (1), 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, the composite electrolyte membrane for PEMFC of the present invention may satisfy both conditions (3) and (4).

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

Condition (4) B ₂ ≤ A ₁ , B ₂ ≤ A ₂ , B ₂ ≤ A ₃

In condition (3), 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 (4), 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.

If the composite electrolyte membrane for PEMFC of the present invention does not satisfy both conditions (3) and (4), there may be a problem of deterioration in uniformity.

)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.

Condition (7) 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, the composite electrolyte membrane for PEMFC of the present invention has the value of condition (8) (condition (8):

) can be satisfied.

condition (8) 0.2 ≤ condition (8) value ≤ 10, preferably 0.5 ≤ condition (8) value ≤ 8, more preferably 1.0 ≤ condition (8) value ≤ 6, even 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]

The method for manufacturing a composite electrolyte membrane for a PEMFC of the present invention may perform a process including the first to fourth steps.

First, in the first step of the method of manufacturing a composite electrolyte membrane for a PEMFC of the present invention, 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 method for manufacturing a composite electrolyte membrane for PEMFC of the present invention, a first electrolyte layer may be formed on one surface of the first support layer prepared in the first step, and on one surface of the second support layer prepared in the first step. A third electrolyte layer may be formed.

Specifically, in the second step of the method for manufacturing a composite electrolyte membrane for PEMFC of the present invention, the electrolyte membrane forming solution described above is coated on one surface of the first support layer, or one surface of the first support layer is impregnated with the electrolyte membrane forming solution. After drying, the first electrolyte layer may be formed by drying.

In addition, the third electrolyte layer may be formed by applying the ionomer mixed solution to one surface of the second support layer or impregnating one surface of the second support layer with the electrolyte membrane forming 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 electrolyte membrane forming solution impregnated in the first support layer and / or the second support layer may decrease, and if it exceeds 200 ° C, the electrolyte membrane and / or membrane- When manufacturing an electrode assembly, bonding properties with electrodes may be deteriorated.

Next, in the third step of the method of manufacturing a composite electrolyte membrane for a PEMFC of the present invention, 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 applying an electrolyte film forming solution to the other surface of the first support layer, or The second electrolyte layer may be formed by impregnating the other surface with an electrolyte film forming solution and then drying the surface.

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 property of the electrolyte membrane forming solution impregnated in the first support layer may decrease, and if it exceeds 200 ° C, the bonding with the electrode during the manufacture of the electrolyte membrane and / or membrane-electrode assembly may deteriorate. may be lowered

The electrolyte film forming solutions of the first to third steps may each be an electrolyte film forming solution containing the durability improver, a cerium-based radical scavenger, and an ionomer described above, and the electrolyte of the first to third steps The composition and composition ratio of the film forming solution may be the same or different.

Finally, in the fourth step of the manufacturing method of the composite electrolyte membrane for PEMFC of the present invention, 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, A composite electrolyte membrane for a PEMFC of the present invention in which the second electrolyte layer, the second support layer, and the third electrolyte layer 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. 4, the membrane-electrode assembly for PEMFC of the present invention includes an anode (oxidation electrode) 200, the aforementioned composite electrolyte membrane 100 for PEMFC of the present invention, and a cathode (reduction electrode) 300. do.

A membrane-electrode assembly according to an embodiment of the present invention includes an anode (oxidation electrode, 200) and a cathode (reduction electrode, 300) positioned opposite to each other with a composite electrolyte membrane (100) interposed therebetween. . At this time, the anode 200 includes an anode gas diffusion layer 3, an anode catalyst layer 2, and an anode electrode substrate 1, and the cathode 300 includes a cathode gas diffusion layer 4, a cathode catalyst layer 5, and a cathode electrode. A substrate 6 may be included.

Specifically, the anode 200 may be formed by sequentially stacking an anode gas diffusion layer 3, an anode catalyst layer 2, and an anode electrode substrate 1, and the anode gas diffusion layer 3 is a composite electrolyte membrane 200 It may be bonded to one side of. In addition, the cathode 300 may be formed by sequentially stacking the cathode gas diffusion layer 4, the cathode catalyst layer 5, and the cathode electrode substrate 6, and the cathode gas diffusion layer 4 is the composite electrolyte membrane 200. It may be bonded to the other side.

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

The anode gas diffusion layer 3 may be formed by applying a gas diffusion layer forming material to one surface of the composite electrolyte membrane 100 .

The anode gas diffusion layer 3 may be provided to prevent rapid diffusion of fuel injected into the fuel cell and to prevent deterioration of ionic conductivity. In addition, the anode gas diffusion layer 3 can control the diffusion rate of fuel through heat treatment or electrochemical treatment. In addition, the anode gas diffusion layer 3 serves as a current conductor between the composite electrolyte membrane 100 for PEMFC and the anode catalyst layer 2, and becomes a passage for gas as a reactant and water as a product. Therefore, the anode gas diffusion layer 3 may have a porous structure with a porosity of 20% to 90% so that gas can pass through. The thickness of the anode gas diffusion layer 3 may be appropriately adopted as needed, and may be, for example, 100 to 400 μm. When the thickness of the anode gas diffusion layer 3 is less than 100 μm, electrical contact resistance between the anode catalyst layer 2 and the anode electrode substrate 1 increases, and the structure may become unstable due to compression. In addition, when the thickness of the anode gas diffusion layer 3 exceeds 400 μm, the movement of gas as a reactant may become difficult.

In addition, the anode gas diffusion layer 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.

The anode catalyst layer 2 is a layer into which an oxidation catalyst is introduced, and the anode catalyst layer 2 may be formed by applying a catalyst layer forming material on the anode gas diffusion layer 3.

A metal catalyst or a metal catalyst supported on a carbon-based support may be used as the material for forming the catalyst layer. 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.

In addition, the anode catalyst layer 2 may include a conductive support and an ion conductive binder (not shown). In addition to this, the anode catalyst layer 2 may include a main catalyst attached to a conductive support. The conductive support may be carbon black, and the ion conductive binder may be a Nafion ionomer or a sulfonated polymer. In addition, the main catalyst may be a metal catalyst, for example platinum (Pt). The anode catalyst layer 2 may be formed using an electroplating method, a spray method, a painting method, a doctor blade method, or a transfer method.

The anode electrode substrate 1 may use a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt, but is not limited thereto, and all anode electrode materials applicable to polymer electrolyte fuel cells may be used. It is possible. The anode electrode substrate 1 may be formed on one surface of the anode catalyst layer 2 through a conventional deposition method, and after forming the anode catalyst layer 2 on the anode electrode substrate 1, the anode gas diffusion layer 3 ) It may be formed by placing the anode catalyst layer 2 and the anode electrode substrate 1 in contact with each other.

The cathode gas diffusion layer 4 may be formed by applying a gas diffusion layer forming material to the other surface of the composite electrolyte membrane 100 .

The cathode gas diffusion layer 4 may be provided to prevent rapid diffusion of gas injected into the cathode 300 and uniformly distribute the gas injected into the cathode 300 . In addition, the cathode gas diffusion layer 4 serves as a current conductor between the composite electrolyte membrane 100 for PEMFC and the cathode catalyst layer 5, and becomes a passage for gas as a reactant and water as a product. Therefore, the cathode gas diffusion layer 4 may have a porous structure with a porosity of 20% to 90% so that gas can pass through. The thickness of the cathode gas diffusion layer 4 may be appropriately adopted as needed, and may be, for example, 100 to 400 μm. When the thickness of the cathode gas diffusion layer 4 is less than 100 μm, electrical contact resistance between the cathode catalyst layer 5 and the cathode electrode substrate 6 increases, and the structure may become unstable due to compression. In addition, when the thickness of the cathode gas diffusion layer 4 exceeds 400 μm, the movement of gas as a reactant may become difficult.

In addition, the cathode gas diffusion layer 4 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.

The cathode catalyst layer 5 is a layer into which a reduction catalyst is introduced, and the cathode catalyst layer 5 may be formed by applying a catalyst layer forming material on the cathode gas diffusion layer 4.

A metal catalyst or a metal catalyst supported on a carbon-based support may be used as the material for forming the catalyst layer. 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.

In addition, the cathode catalyst layer 5 may include a conductive support and an ion conductive binder (not shown). In addition, the cathode catalyst layer 5 may include a main catalyst attached to the conductive support. The conductive support may be carbon black, and the ion conductive binder may be a Nafion ionomer or a sulfonated polymer. In addition, the main catalyst may be a metal catalyst, for example platinum (Pt). The cathode catalyst layer 5 may be formed using an electroplating method, a spray method, a painting method, a doctor blade method, or a transfer method.

For the cathode electrode substrate 6, a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt may be used, but is not limited thereto, and any cathode electrode material applicable to a polymer electrolyte fuel cell may be used. It is possible. The cathode electrode substrate 6 may be formed on one side of the cathode catalyst layer 5 through a conventional deposition method, and after forming the cathode catalyst layer 5 on the cathode electrode substrate 6, the cathode gas diffusion layer 4 ) It may be formed by disposing the cathode catalyst layer 5 and the cathode electrode substrate 6 so as to be in contact with each other.

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: Preparation of durability improver (GDC) and electrolyte film forming solution

(1) Manufacture of durability improver

GDC represented by Chemical Formula 1-1 was prepared by adding a mixed solution of a cerium precursor (cerium nitrate) and a gadolinium precursor (gadolinium nitrate) dropwise to an aqueous solution under certain environmental conditions to obtain a coprecipitate. At this time, the particle size (D ₅₀ ) of the GDC was about 250 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 is an integer satisfying 0<y≤0.25.

(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 durability improver (GDC), 0.25 wt% of the radical scavenger (CeZnO), and the remaining amount of the ionomer.

Example 2

(1) Manufacture of durability improver

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

[Formula 1-2]

Gd _x Ce _1-x O _2-y

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

(2) Preparation of electrolyte membrane forming solution

Using the same perfluorosulfonic acid-based ionomer as in Example 1, 0.5% by weight of the durability improver (GDC), 0.25% by weight of a radical scavenger (CeZnO), and the remaining amount of the perfluorinesulfonic acid-based ionomer were mixed to form an electrolyte membrane solution was manufactured.

Example 3

The same perfluorine sulfonic acid-based ionomer and durability improver as in Example 1 were used, but 0.50% by weight of the durability improver (GDC), 0.25% by weight of a radical scavenger (Ce(NO ₃ ) ₆ 6H ₂ O) and the remaining amount of the above A solution for forming an electrolyte membrane was prepared by mixing the perfluorine sulfonic acid-based ionomer.

Example 4

The same perfluorine sulfonic acid-based ionomer and durability improver as in Example 1 were used, but 0.50% by weight of the durability improver (GDC), 1.00% by weight of a radical scavenger (Ce(NO ₃ ) ₆ 6H ₂ O) and the remaining amount of the above A solution for forming an electrolyte membrane was prepared by mixing the perfluorine sulfonic acid-based ionomer.

Comparative Example 1

Without using a high durability improver, the perfluorinesulfonic acid-based ionomo itself of Example 1 was prepared as an electrolyte membrane forming solution.

Comparative Example 2

An electrolyte membrane forming solution was prepared by mixing 0.75% by weight of a radical scavenger (CeZnO) and the remaining amount of the perfluorine sulfonic acid-based ionomer without using a durability enhancing agent.

Examples 5 to 6 and Comparative Example 4

The durability improver and the electrolyte membrane forming solution were prepared in the same manner as in Example 1, but the electrolyte membrane forming solution was prepared by varying the durability improver or its content as shown in Table 1 below.

division durability enhancer Type/content of Ce-based radical scavenger ionomer GDC
type/
Particle size (D ₅₀ ) BET
specific surface area
(m ² /g) in an electrolyte forming solution
Durability enhancer content Example 1 Formula 1-1/250 nm 125 0.5% by weight CeZnO
/0.25% by weight Remainder
balance
100% by weight Example 2 Formula 1-2
/275nm 150 0.5% by weight CeZnO
/0.25% by weight Example 3 Formula 1-1/250 nm 125 0.5% by weight Ce(NO ₃ ) ₆ 6H ₂ O/0.5% by weight Example 4 Formula 1-1/250 nm 125 0.5% by weight Ce(NO ₃ ) ₆ 6H ₂ O/1.0% by weight Example 5 Formula 1-1/250 nm 125 0.5% by weight CeZnO
/3.0% by weight Example 6 Formula 1-1/250 nm 125 5.0% by weight CeZnO
/2.5% by weight Comparative Example 1 - - - - 100% by weight Comparative Example 2 - - - CeZnO
/0.75% by weight Remainder
balance
100% by weight Comparative Example 3 Formula 1-1/250 nm 125 0.5% by weight CeZnO
/5.3% by weight Comparative Example 4 Formula 1-1/250 nm 125 10.2% by weight CeZnO
/2.5% by weight

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 fluorine ion concentration in the Fenton solution, and the results are shown in Table 2 below.

In addition, FER measurement graphs of Examples 1 to 5 and Comparative Examples 1 to 4 are shown in FIG. 5A.

(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, initial performance evaluation at 65 ° C / 100% relative humidity (open circuit voltage, OCV, open circuit voltage ) was measured, and the measurement results of Examples 1 to 4 and Comparative Example 1 are shown in FIG. 5B. 5b, there was no difference in initial performance.

After operating the membrane-electrode assembly for 200 hours under harsher environmental conditions (90°C/30% relative humidity) than actual cell operating conditions, the degradation rate (%, voltage drop rate) was measured, and the results are shown in Table 2 below. showed up

division FER
(umol/gh) After driving 200 hours,
Deterioration rate (%) Example 1 6.72 4.1 Example 2 6.61 5.5 Example 3 5.69 5.2 Example 4 5.27 4.3 Example 5 4.55 3.1 Example 6 4.03 2.9 Comparative Example 1 15.1 14.9 Comparative Example 2 8.47 9.1 Comparative Example 3 4.21 2.8 Comparative Example 4 3.68 7.1

Looking at the measurement results of the fluorine ion release rate in Table 2, the electrolyte membrane of Comparative Example 1 exhibited a high fluoride ion release rate of about 15.1 umol/g.h. On the other hand, Examples 1 to 6 to which the durability improver GDC was applied showed a relatively very low fluorine ion release rate.

After 200 hours of operation, Comparative Example 1 and Comparative Example 2, which did not use the durability improver, showed a problem in that the degradation rate rapidly increased. On the other hand, in the case of Examples 1 to 6, it can be confirmed that the thermal efficiency is relatively low compared to Comparative Examples 1 to 2, and through this, it can be confirmed that the durability is greatly improved.

And, Comparative Example 3 in which the radical scavenger was used excessively had a low fluorine ion release rate and a low degradation rate, but, referring to FIG. 5B, there was a problem in that the initial performance was very low.

In addition, in the case of Comparative Example 4 using more than 10% by weight of the durability improver, compared to Example 6, the fluorine ion release rate was low, but there was a problem that the degradation rate after 200 hours of operation rather greatly increased, which is because the durability improver Rather, it is judged that it acts as an impurity and affects the performance decrease.

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

A solution for forming an electrolyte film was prepared by mixing 0.5% by weight of the durability improver (GDC) prepared in Example 1, 1.0% by weight of CeZnO as a radical scavenger, and the remaining amount of a perfluorine-based sulfonated ionomer (solvay, aquivion D72-25DS) did

(2) The porous PTFE support prepared in Support 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 film without using a durability enhancer was prepared by mixing 1.0 wt% of CeZnO, a radical scavenger, and the remaining amount of a perfluorine-based sulfonated ionomer (solvay, aquivion D72-25DS).

(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 2: Measurement of Physical Properties of Composite Electrolyte Membrane for PEMFC

(1) Durability test (Fenton test)

Each of the composite electrolyte membranes for PEMFC 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 or more After drying, the mass is measured. The prepared test piece was immersed in 200 g of a solution prepared by adding 3 ppm of Fe ²⁺ 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 3 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 3 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℃) 0.69 0.58 0.56 0.61 0.70 0.67 Durability (umol/gh) 3.2 3.3 3.3 3.3 3.2 13.8 Dimensional expansion rate
(%) MD direction One One One One 3 One TD direction 5 5 5 5 8 5 The tensile strength
(Mpa) MD direction 64.5 68.3 68.7 64.3 49.8 63.2 TD direction 61.9 63.4 62.4 58.8 43.3 61.3

As can be seen in Table 3, 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 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, after preparing solutions for forming an electrolyte membrane having different contents of the durability improver of Example 1, the first to third electrolyte layers were formed using the solution, respectively, to prepare a composite electrolyte membrane.

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

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 layers (4 μm) are stacked is prepared, but the content of the durability improver in the electrolyte film forming solution is varied, and then the content of the durability improver in the electrolyte layer is determined as shown in Table 4 below. Each composite electrolyte membrane was prepared differently, and Preparation Example 3-2 and Comparative Preparation Examples 3-1 to 3-2 were performed.

Experimental Example 3: Measurement of Physical Properties of Composite Electrolyte Membrane for PEMFC

As shown schematically in FIG. 4, the anode electrode 1, the anode catalyst layer 2, the anode gas diffusion layer 3, the composite electrolyte membrane 100, the cathode gas diffusion layer 4, the cathode catalyst layer 5, and the cathode electrode substrate A membrane-electrode assembly for PEMFC equipped with (6) was prepared.

At this time, the composite electrolyte 100 uses the composite electrolyte membranes of Preparation Example 2-1, Preparation Examples 3-1 to 3-2 and Comparative Preparation Examples 3-1 to 3-2, respectively, and each first electrolyte layer is In the anode direction, the third electrolyte layer was provided in the cathode direction.

In addition, the performance and durability measurement results according to the added content of the durability improver and application design in the manufactured membrane-electrode assembly are shown in Table 4 below.

division manufacturing example
2-1 manufacturing example
3-1 manufacturing example
3-2 Comparative Manufacturing Example
3-1 Comparative Manufacturing Example
3-2 Durability improver content in the first electrolyte layer (% by weight) 0.5 0.5 1.5 1.5 2.5 Durability improver content in the second electrolyte layer (% by weight) 0.5 1.0 0.5 1.0 1.5 Durability improver content in the third electrolyte layer (% by weight) 0.5 1.5 1.5 0.5 0.5 Performance (V/1A@65℃) 0.69 0.70 0.66 0.65 0.60 Endurance (umol/gh) 3.20 2.55 2.71 3.10 3.16

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 electrode substrate 2: anode catalyst layer
3: anode gas diffusion layer 4: cathode gas diffusion layer
5: cathode catalyst layer 6: cathode electrode substrate
11: first 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 (14)

delete delete delete In the electrolyte membrane containing a cerium (Ce)-based radical scavenger,
A durability improver including a compound represented by Formula 1 doped with gadolinium (Gd) in a ceria lattice, a cerium (Ce)-based radical scavenger, and an ionomer,
The particle size (D50) of the durability improver is 50 to 1,000 nm, and the BET specific surface area is 10 to 500 m ² /g,
0.01 to 10% by weight of the durability improver,
An electrolyte membrane for PEMFC, comprising the durability improver and the cerium-based radical scavenger in a weight ratio of 1:0.2 to 5.0;
[Formula 1]
Gd _x Ce _1-x O _2-y
In Formula 1, x is an integer that satisfies 0<x≤0.3, y is an oxygen vacancy value that makes the compound electrically neutral, and is an integer that satisfies 0<y≤0.25.
delete The first electrolyte layer, the first support layer, and the second electrolyte layer are composite electrolyte membranes in which electrolyte layers are sequentially stacked,
At least one layer selected from among the first electrolyte layer and the second electrolyte layer includes the electrolyte membrane of claim 4,
The composite electrolyte membrane for PEMFC, characterized in that the average thickness of the composite electrolyte membrane for PEMFC is 5 ~ 30㎛.
According to claim 6,
The composite electrolyte membrane for PEMFC is a composite electrolyte membrane for PEMFC, characterized in that it satisfies the following condition (1).
Condition (1) B ₁ ≤ A ₁ , B ₁ ≤ A ₂
In condition (1), 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.
[Claim 7] The composite electrolyte membrane for PEMFC according to claim 6, wherein the composite electrolyte membrane for PEMFC satisfies the following condition (2);
Condition (2) A ₁ ≤ A ₂
In condition (2), A ₁ represents the content of the durability improver in the first electrolyte layer, and A ₂ represents the content of the durability improver in the second electrolyte layer.
A composite electrolyte membrane 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,
At least one layer selected from among the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer includes the electrolyte membrane of claim 4,
The composite electrolyte membrane for PEMFC, characterized in that the average thickness of the composite electrolyte membrane for PEMFC is 5 ~ 30㎛.
The method of claim 9, wherein the composite electrolyte membrane for the PEMFC,
a third support layer formed on one surface of the third electrolyte layer; and a fourth electrolyte layer formed on one side of the third support layer. A composite electrolyte membrane for PEMFC, characterized in that it further comprises.
According to claim 9,
The composite electrolyte membrane for PEMFC, characterized in that satisfying both the following conditions (3) and (4).
(3) B ₁ ≤ A ₁ , B ₁ ≤ A ₂ , B ₁ ≤ A ₃
(4) B ₂ ≤ A ₁ , B ₂ ≤ A ₂ , B ₂ ≤ A ₃
In the above condition (3), A ₁ is the thickness of the first electrolyte layer, A ₂ is the thickness of the second electrolyte layer, A ₃ is the thickness of the third electrolyte layer, B ₁ is the thickness of the first support layer, In condition (4), A ₁ is the thickness of the first electrolyte layer, A ₂ is the thickness of the second electrolyte layer, A ₃ is the thickness of the third electrolyte layer, and B ₂ is the thickness of the second support layer.
[Claim 10] The composite electrolyte membrane for PEMFC according to claim 9, wherein the composite electrolyte membrane for PEMFC satisfies the following condition (5) or condition (6);
Condition (5) A ₁ ≤ A ₂ ≤ A ₃
Condition (6) A ₂ ≤ A ₁ , B ₂ ≤ A ₃ , A ₁ ≤ A ₃
In the above conditions (5) and (6), A ₁ is the content of the durability improver in the first electrolyte layer, A ₂ is the content of the durability improver in the second electrolyte layer, and A ₃ is the content of the durability improver in the third electrolyte layer indicates
anode (oxidation electrode); The electrolyte membrane for the PEMFC of claim 4; and cathode (reduction electrode); A membrane-electrode assembly for PEMFC comprising a.
anode (oxidation electrode); The composite electrolyte membrane for the PEMFC of claim 6; and cathode (reduction electrode); A membrane-electrode assembly for PEMFC comprising a.

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