KR102118061B1 - Complex electrolyte membrane for PEMFC, manufacturing method thereof and membrane electrode assembly containing the same - Google Patents

Abstract

The present invention relates to a composite electrolyte membrane for a polymer electrolyte membrane fuel cell, a membrane-electrode assembly containing the same, a fuel cell and a method for manufacturing the same, and more specifically, the content and distribution of radical scavengers in the composite electrolyte membrane It relates to an invention that can provide a composite electrolyte membrane and a membrane-electrode assembly with improved durability by adjusting.

Description

Composite electrolyte membrane for PEMFC, manufacturing method thereof, and membrane-electrode assembly for PEMFC comprising the same{Complex electrolyte membrane for PEMFC, manufacturing method thereof and membrane electrode assembly containing the same}

The present invention relates to a composite electrolyte membrane used in a polymer electrolyte membrane fuel cell (PEMFC), a composite electrolyte membrane prepared by introducing a specific support and having a different radical scavenger distribution in each ionomer layer, and a membrane-electrode assembly using the same , A fuel cell including the same, and a method for manufacturing the same.

A fuel cell is a power generation system that directly converts chemical energy generated by electrochemically reacting fuel (hydrogen or methanol) with an oxidizing agent (oxygen) into electrical energy.It is an eco-friendly feature with high energy efficiency and low emission of pollutants. Research and development. Fuel cells can be used by selecting fuel cells for high temperature and low temperature according to the application field, and are generally classified according to the type of electrolyte. For high temperature, solid oxide fuel cells (SOFC) and molten carbonate are used. There are fuel cells (Molten Carbonate Fuel Cell, MCFC), and for low temperature, alkaline electrolyte fuel cells (AFC) and polymer electrolyte fuel cells (PEMFC) are being developed.

When a polymer electrolyte fuel cell is subdivided, a hydrogen ion exchange membrane fuel cell (PEMFC) using hydrogen gas as fuel, and direct methanol used by supplying liquid methanol to the anode as a direct fuel Direct Cell Fuel Cell (DMFC). Polymer electrolyte fuel cells are in the spotlight as portable, automotive, and household power supplies with advantages such as low operating temperatures below 100°C, elimination of leakage problems due to the use of solid electrolytes, fast start-up and response characteristics, and excellent durability. In particular, as a high-power fuel cell with a higher current density than other types of fuel cells, miniaturization is possible, and research into a portable fuel cell continues.

The unit cell structure of such a fuel cell has a structure in which an anode (anode) and a cathode (Cathode) are coated on both sides of an electrolyte membrane made of a polymer material, which is a membrane-electrode assembly (Membrane) Electrode Assembly, MEA). This membrane-electrode assembly (MEA) is a portion where 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).

In the anode, hydrogen or methanol, which is fuel, is supplied, and an oxidation reaction of hydrogen occurs to generate hydrogen ions and electrons. In the cathode, hydrogen ions and oxygen that have passed through the polymer electrolyte membrane are combined to generate water by the reduction reaction of oxygen. .

This membrane-electrode assembly forms such that the electrode catalyst layers of the anode and cathode are coated on both sides of the ion conductive electrolyte membrane, and the material forming the electrode catalyst layer is Pt (platinum) or Pt-Ru (platinum-ruthenium). The catalyst material of is supported on a carbon carrier. In the membrane-electrode assembly (MEA), which can be seen as a key component of the electrochemical reaction of a fuel cell, an ion-conducting electrolyte membrane and a platinum catalyst, which have a high price composition ratio, are used. It is regarded as the most important part to improve the performance and price competitiveness of.

The conventional method of manufacturing a commonly used MEA is to prepare a paste by mixing a catalyst material with a hydrogen ion conductive binder, that is, a fluorine-based Nafion Ionomer and water and/or an alcohol solvent, It is coated with carbon cloth or carbon paper, which serves as an electrode support for supporting the catalyst layer and also serves as a gas diffusion layer, and then uses a method of drying and thermally welding to a hydrogen ion conductive electrolyte membrane.

In the catalyst layer, a redox reaction of hydrogen and oxygen by a catalyst; The movement of electrons by adhered carbon particles; Securing passages for supplying hydrogen, oxygen and moisture and discharging excess gas after reaction; The movement of oxidized hydrogen ions must be done simultaneously. Moreover, in order to improve the performance, it is necessary to reduce the activation polarization by increasing the area of the triple phase boundary where the feed fuel meets the catalyst and the ion conductive polymer electrolyte membrane, and decrease the activation polarization, and the interface between the catalyst layer and the electrolyte membrane and the catalyst layer It is necessary to reduce the resistance polarization at the interface by uniformly bonding the interface between the and gas diffusion layer. Therefore, in order to improve the performance of the fuel cell by reducing the interface resistance between the catalyst layer and the electrolyte membrane as much as possible, not only the bonding strength of the catalyst layer and the electrolyte membrane must be present during the manufacture of the MEA, but also the interface bonding between the catalyst layer and the electrolyte membrane during fuel cell operation. It must be maintained.

Accordingly, in recent years, although technology has been actively developed 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, the interface uniformity still has limited disadvantages.

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

In addition, as the movement and use time of hydrogen ions increase when the fuel cell is driven, the interface between the catalyst layer and the electrolyte membrane and the interface bonding property between the catalyst layer and the gas diffusion layer are weakened and separated from each other. Accordingly, when applied to a fuel cell, it may cause a decrease in the performance of the fuel cell.

In order to shorten the movement time of hydrogen ions, the thickness of the electrolyte membrane must be reduced, and for this purpose, there is a method of thinning the thickness of the porous support constituting the electrolyte membrane, in order to thin the thickness of the support, properties such as strength of the support during high stretching In addition to this large reduction, there was a problem in that economic efficiency and commerciality were poor due to a high defect rate in the production of the support.

Republic of Korea Patent No. KR 2010-0077483 A (2010.07.08)

The present invention has been devised to solve the above problems, and it is possible to effectively remove radicals by adjusting the distribution of radical scavengers used in the electrolyte membrane to improve the durability of the polymer electrolyte membrane fuel cell (PEMFC), thereby improving durability. It is intended to provide a composite electrolyte membrane for PEMFC. In addition, by applying a specific support to the PEMFC composite electrolyte membrane, the overall thickness of the fuel cell electrolyte membrane is reduced to improve the performance of the fuel cell composite electrolyte membrane, a method of manufacturing the same, and a membrane-electrode assembly using the same, a polymer electrolyte membrane fuel cell Want to provide.

The PEMFC (Polymer Electrolyte Membrane Fuel Cell) composite electrolyte membrane of the present invention for solving the above problems is a first ionomer (ionomer) layer disposed in the anode (anode) direction; It includes; a support layer and a second ionomer layer disposed in the cathode direction; the first ionomer layer and the second ionomer layer include a radical scavenger to satisfy the following Equation 1.

[Equation 1] 0

Average content of radical scavenger in the first ionomer layer <Average content of radical scavenger in the second ionomer layer

As a preferred embodiment of the present invention, the average radical scavenger content in the first ionomer layer and the average radical scavenger content in the second ionomer layer may be included in a weight ratio of 1: 1.25 to 10.

As a preferred embodiment of the present invention, in the composite electrolyte membrane of the present invention, the radical scavenger distribution in the first ionomer layer may satisfy Equation 2 below.

[Equation 2]

D _60~100 > D _0~40

In Equation 2, D _0-40 and D _60-100 are the content of the radical scavenger in the total weight of the radical scavenger in the ionomer layer at a distance away from the bonding surface between the first ionomer layer and the support in the thickness direction of the support. As a meaning (% by weight), when the end distance of the first ionomer layer farthest from the bonding surface between the first ionomer layer and the support is 100%, D _0-40 is the first ionomer from the bonding surface. The content of the radical scavenger (% by weight) in the first ionomer layer located at a distance of 10% to 40% in the direction of the end of the layer, D _{60 to 100} is 60% in the direction of the end of the first ionomer layer from the bonding surface It means the content (% by weight) of radical scavenger in the first ionomer layer located at a distance of ~ 90%.

As a preferred embodiment of the present invention, in the composite electrolyte membrane of the present invention, with respect to the radical scavenger content contained in the first ionomer layer, the radical scavenger content of D _{60 to 100} is 0.6 to 2.4 weight %, and the radical scavenger content of D _0-40 may be 0.01 to 0.6% by weight.

As a preferred embodiment of the present invention, in the composite electrolyte membrane of the present invention, the distribution of radical scavenger in the second ionomer layer is PEMFC composite electrolyte membrane, characterized in that it satisfies the following equation 3;

[Equation 3]

D _60~100 > D _0~40

In Equation 3, D _0-40 and D _60-100 are the content of the radical scavenger in the total weight of the radical scavenger in the ionomer layer at a distance away from the bonding surface between the second ionomer layer and the support in the thickness direction of the support. (% by weight), when considering the end distance of the second ionomer layer farthest from the bonding surface between the first ionomer layer and the support, based on 100%, D _0-40 is the second ionomer from the bonding surface. The content (%) of the radical scavenger in the second ionomer layer located at a distance of 10% to 40% in the direction of the end of the layer, and D _{60 to 100} is 60% to the end direction of the second ionomer layer from the bonding surface It means the content (%) of radical scavengers in the second ionomer layer located at a distance of 90%.

As a preferred embodiment of the present invention, in the composite electrolyte membrane of the present invention, with respect to the radical scavenger contained in the second ionomer layer, the radical scavenger content of D _{60 to 100} is 0.8 to 3.0 wt% And, the content of the radical scavenger of D _0-40 may be 0.1 to 0.8% by weight.

As a preferred embodiment of the present invention, in the composite electrolyte membrane of the present invention, the radical scavenger may include one selected from inorganic radical scavengers and organic radical scavengers.

As a preferred embodiment of the present invention, the inorganic radical scavenger is a group 4, 5, 6, 7, 8, 9, 10, 11 elements, Zn, Al, La and Ce It may include an oxide of a metal containing one or more selected.

As a preferred embodiment of the present invention, the inorganic radical scavenger may include cerium oxide, zirconium oxide, manganese oxide, aluminum oxide, vanadium oxide, metal oxide including cerium and zinc.

As a preferred embodiment of the present invention, the inorganic radical scavenger is CeO, CeO ₂ , Ce ₂ O ₃ , CePO ₄ , Ce ₃ (PO ₄ ) ₄ , Zn ₃ (PO ₄ ) ₂ , ZnO, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , ZrO ₂ , MoO _{3 ,} CrPO ₄ , AlPO ₄ And FePO ₄ , It may include one or more selected from.

As a preferred embodiment of the present invention, the inorganic radical scavenger may include a metal oxide including cerium and zinc, and a crystal structure composed of a cerium (Ce) atom, a zinc (Zn) atom, and an oxygen (O) atom. It includes metal oxide particles having a, the crystal structure may be a crystal structure of a type in which some of the zinc atoms are substituted with cerium atoms in the ZnO crystal structure.

As a preferred embodiment of the present invention, the metal oxide particles are measured by Energy Dispersive Spectrometer (EDS), 12 to 91% by weight of Ce (cerium), 7 to 84.5% by weight of Zn (zinc), and the remaining amount of O (oxygen) It may include.

As a preferred embodiment of the present invention, the support used in the composite electrolyte membrane of the present invention may include a PTFE (Poly tetra fluoro ethylene) porous support.

As a preferred embodiment of the present invention, the PTFE porous support has a tensile strength of 40 MPa or more and a biaxial (width direction) tensile strength of 40 MPa or more when measured according to ASTM D 882. Can be.

As a preferred embodiment of the present invention, the PTFE porous support of the present invention is measured in accordance with ASTM D 882, the tensile strength in the uniaxial direction (longitudinal direction) of 40 MPa or more and the tensile strength in the biaxial direction (width direction). 40 MPa or more.

As a preferred embodiment of the present invention, the PTFE porous support of the present invention may satisfy the following equation 4 when measured in accordance with ASTM D 882, the uniaxial modulus and biaxial modulus values.

[Equation 4]

0 ≤ │(1 axis direction modulus-2 axis direction modulus)/(1 axis direction modulus)×100%│≤ 54%

As a preferred embodiment of the present invention, the PTFE porous support may have an axial direction (lengthwise) stretching ratio of 3 to 10 times, and a biaxial direction (width direction) stretching ratio of 15 to 50 times.

As a preferred embodiment of the present invention, the PTFE porous support may have a axial direction (lengthwise) stretching ratio of 6 to 9.5 times, and a biaxial direction (width direction) stretching ratio of 25 to 45 times.

As a preferred embodiment of the present invention, the PTFE porous support may have a axial direction (lengthwise) stretching ratio of 6.2 to 9 times, and a biaxial direction (width direction) stretching ratio of 28 to 45 times.

As a preferred embodiment of the present invention, the porous support of the present invention has an elongation ratio (or aspect ratio) in a uniaxial direction (longitudinal direction) and a biaxial direction (or transverse direction) of 1: 3.00 to 8.5, preferably 1: 3.50. ~ 7.0.

As a preferred embodiment of the present invention, the PTFE porous support has an average pore size of 0.080 μm to 0.20 μm, and an average porosity of 60 to 90%.

As a preferred embodiment of the present invention, the PTFE porous support may have an average thickness of 5 ~ 25㎛.

As a preferred embodiment of the present invention, the PEMFC composite electrolyte membrane of the present invention may have a uniaxial modulus of 50 MPa or more and a biaxial modulus of 50 MPa or more when measured according to ASTM D 882.

As a preferred embodiment of the present invention, the fuel cell electrolytic membrane of the present invention has a tensile strength of 50 MPa or more in the uniaxial direction (longitudinal direction) and a tensile strength in the biaxial direction (width direction) as measured according to ASTM D 882. 48 MPa or more.

Another object of the present invention relates to a method for manufacturing a composite electrolyte membrane of various types described above, comprising: a first step of preparing a polytetrafluoroethylene (PTFE) porous support; A second step of forming a first ionomer layer on one surface of the PTFE porous support; A third step of forming a second ionomer layer on the other surface of the support on which the first ionomer layer is formed; And a fourth step of heat-treating the PTFE porous support on which the first ionomer layer and the second ionomer layer are formed; a composite electrolyte membrane for PEMFC can be prepared by performing a process including the process.

As a preferred embodiment of the present invention, the PTFE porous support in Step 1 comprises steps 1-1 of mixing and stirring PTFE powder and a liquid lubricant to prepare a paste; 1-2 steps of aging the paste; Steps 1-3 for producing an unbaked tape by extruding and rolling the aged paste; After drying the green tape, steps 1-4 to remove the liquid lubricant; Step 1-5 of uniaxially stretching the unbaked tape from which the lubricant has been removed; Steps 1-6 of biaxially stretching the uniaxially stretched micro tape; And 1-7 steps of firing; can be prepared by performing a process comprising.

As a preferred embodiment of the present invention, the paste of step 1-1 may include 15 to 35 parts by weight of lubricant relative to 100 parts by weight of PTFE powder.

As a preferred embodiment of the present invention, as the liquid lubricant, in addition to hydrocarbon oils such as liquid paraffin, naphtha, white oil, toluene, xylene, various alcohols, ketones, esters, and the like can be used, and preferably liquid paraffin , Naphtha and white oil may be used.

As a preferred embodiment of the present invention, the aging in step 1-2 may be performed by leaving for 12 to 24 hours at a temperature of 30°C to 70°C.

As a preferred embodiment of the present invention, the extrusion of steps 1-3 can be performed by compressing the aged paste in a compressor to produce a PTFE block, and then extruding the PTFE block at a pressure of 0.069 to 0.200 Ton/cm ^2. have.

As a preferred embodiment of the present invention, the rolling in steps 1-3 may be performed by a calendering process under 50 to 100° C. with a hydraulic pressure of 5 to 10 MPa.

As a preferred embodiment of the present invention, the drying process in steps 1-4 is a process for removing the lubricant, and drying may be performed at 100°C to 200°C while moving the unfinished tape at a speed of 1 to 5M/min.

As a preferred embodiment of the present invention, the uniaxial stretching in steps 1-5 is 3 to 10 times, preferably 6 to 9.5 times, more preferably 6.2 to 9 times, the unstretched tape from which the lubricant has been removed. Stretching can be performed.

As a preferred embodiment of the present invention, the uniaxial stretching in steps 1-5 may be performed at a stretching speed of 6 to 12 M/min, under a stretching temperature of 260°C to 350°C.

As a preferred embodiment of the present invention, the biaxial stretching in steps 1-6 is 15 to 50 times, preferably 25 to 45 times, more preferably 28 to 45 times the unstretched unstretched tape in the width direction. Stretching can be performed.

As a preferred embodiment of the present invention, the biaxial stretching in steps 1-6 can be performed at a stretching speed of 10 to 20 M/min, under a stretching temperature of 150°C to 260°C.

As a preferred embodiment of the present invention, the firing in steps 1-7 can be performed under a temperature of 350°C to 450°C.

As a preferred embodiment of the present invention, steps 1-8 impregnating the porous support prepared by performing steps 1-7 in a fluorine-based ionomer solution; And steps 1-9 of drying and heat-treating the impregnated PTFE porous support.

As a preferred embodiment of the present invention, the fluorine-based ionomer solution in steps 1-8 may further include at least one hygroscopic agent selected from the group consisting of zeolite, titania, zirconia, and montmorillonite.

As a preferred embodiment of the present invention, the fluorine-based ionomer solution in steps 1-8 may further include 0.05 to 5% by weight of hollow silica in the total weight of the solution.

As a preferred embodiment of the present invention, the fluorine-based ionomer may include one or more selected from Nafion, Flemion and Aciplex.

As a preferred embodiment of the present invention, the drying in steps 1-9 is 60°C to 100°C? The temperature is performed for 1 to 30 minutes, and the heat treatment is 100°C to 200°C? It may be performed at a temperature of 1 minute to 5 minutes.

As a preferred embodiment of the present invention, the porous support heat-treated in steps 1-9 may have a closed pore volume of 90% by volume or more with respect to the total pore volume.

Another object of the present invention relates to a PEMFC membrane-electrode assembly (MEA), comprising: an anode (oxide electrode); Anode catalyst layer; The composite electrolyte membrane for PEMFC; Cathode catalyst layer; And a cathode (reduction electrode).

As a preferred embodiment of the present invention, a gas diffusion layer may be further included between the anode and the anode catalyst layer and the cathode and the cathode catalyst layer.

Another object of the present invention relates to a polymer electrolyte membrane fuel cell, an electric generator for generating electricity through an electrochemical reaction between a fuel and an oxidizing agent; A fuel supply unit supplying fuel to the electricity generation unit; And an oxidizing agent supplying part for supplying an oxidizing agent to the generating part, wherein the electricity generating part includes the membrane-electrode assembly and a separator.

As a preferred embodiment of the present invention, the polymer electrolyte membrane fuel cell includes a membrane-electrode assembly and a separator, and a first step of forming an electricity generating unit that generates electricity through an electrochemical reaction between the fuel and the oxidizing agent; Forming a stack with a separator interposed between the membrane-electrode assembly; Forming a fuel supply unit supplying fuel to the electricity generation unit; And four steps of forming an oxidizing agent supplying part for supplying an oxidizing agent to the electricity generating part.

Since the composite electrolyte membrane for PEMFC of the present invention has an optimum content and distribution of radical scavengers, it is possible to effectively improve the durability of the membrane-electrode assembly by efficiently capturing radicals such as HO · and/or HOO · . In addition, the performance of the fuel cell may be improved by applying a specific support to reduce the overall thickness of the composite electrolyte membrane.

1 is a schematic diagram of a composite electrolyte membrane for PEMFC according to one preferred embodiment of the present invention.
2 is a schematic diagram of a composite electrolyte membrane for PEMFC according to a preferred embodiment of the present invention, and is a schematic diagram for explaining the radical scavenger distribution in the ionomer layer of the composite electrolyte membrane.
3 is a SEM measurement photo of CeZnO radical scavenger prepared in Preparation Example 2-1.
4 is an EDS (Energy Dispersive Spectrometer, or EDAX) measurement results of the CeZnO radical scavenger prepared in Preparation Example 2-1.
5A and 5B are CeZnO metal oxide particles of Preparation Example 2-2 This is the result of nanoparticle size analysis before and after mixing the dispersion with Nafion.
6A and 6B show CeO ₂ Metal oxide particles This is the result of nanoparticle size analysis before and after mixing the dispersion with Nafion.
7 is a result of the dispersion stability measurement experiment conducted in Experimental Example 3, (a) is a picture taken immediately after mixing CeZnO 1% by weight and Nafion, (b) 24 hours after taking the picture of (a) This is a picture taken after the passage. And, (c) CeO ₂ This is a picture taken immediately after mixing weight% and Nafion, and (d) is a picture taken 24 hours after taking the picture in (c).
8 is a schematic diagram of a membrane-electrode assembly according to a preferred embodiment of the present invention.

Hereinafter, the composite electrolyte membrane for a PEMFC (Polymer Electrolyte Membrane Fuel Cell) of the present invention will be described in more detail.

1, the composite electrolyte membrane 10 for PEMFC of the present invention comprises: a first ionomer layer 2 disposed in the anode direction; It includes; a support layer (1) and a second ionomer layer (3) disposed in the cathode (cathode) direction. The first ionomer layer 2 and the second ionomer layer 3 include a radical scavenger.

The radicals generated during fuel cell operation or at rest occur relatively more at the anode than at the cathode, and in the electrolyte layer formed on both sides of the support, the electrolyte layer portion in the electrode (anode or cathode) direction than the support direction portion of the electrolyte layer in the electrolyte layer Tends to generate more and/or more radicals. Therefore, the present invention is to improve the durability of the membrane-electrode assembly while significantly preventing problems caused by excessive use of the radical scavenger by controlling the distribution and the amount of use in the electrolyte membrane (layer) of the radical scavenger.

To this end, the present invention uses a radical scavenger in the first ionomer layer and the second ionomer layer to satisfy the following equation 1.

[Equation 1]

Average content of radical scavenger in the first ionomer layer <Average content of radical scavenger in the second ionomer layer

And, preferably, the average content of the radical scavenger in the first ionomer layer and the average content of the radical scavenger in the second ionomer layer are in a ratio of 1: 1.25 to 10, preferably 1: 1.25 to 5, and more preferably It is good to include in a weight ratio of 1: 1.25 to 3.

In addition, the distribution of radical scavengers in each of the first ionomer layer and the second ionomer layer is preferably increased in the direction of the electrode (anode or cathode) from the support toward the electrode as shown in the schematic diagram in FIG. 2. .

More specifically, the distribution of radical scavengers in the first ionomer layer satisfies Equation 2 below. And, with respect to the radical scavenger content in the first ionomer layer, the radical scavenger content of D _{60 to 100} is 0.6 to 2.4 wt%, and the radical scavenger content of D _{0 to 40} is 0.01 to 0.6 wt% It is good to be.

[Equation 2]

D _60~100 > D _0~40

In Equation 2, D _{0 to 40} and D _{60 to 100} are ionomer layers at a distance away from the bonding surface between the first ionomer layer and the support in the thickness direction of the support (dotted region L1 or ionomer layer region L2 in FIG. 2). It means the content (% by weight) of radical scavenger in the total weight of the radical scavenger, and the end distance of the first ionomer layer farthest from the bonding surface between the first ionomer layer and the support is based on 100%. In this case, D _0-40 denotes the content (% by weight) of radical scavengers in the first ionomer layer located at a distance of 10% to 40% from the bonding surface toward the end of the first ionomer layer, D _60-100 Denotes the content (% by weight) of radical scavengers in the first ionomer layer located at a distance of 60% to 90% in the direction of the end of the first ionomer layer from the bonding surface.

In addition, the distribution of radical scavengers in the second ionomer layer preferably satisfies the following equation 3, and preferably, with respect to the radical scavenger content in the second ionomer layer, the radical scavenger content of D' _{60 ~100} Silver is 0.8 ~ 3.0% by weight, D' _{0 ~ 40} of the radical scavenger content is preferably 0.1 ~ 0.8% by weight.

[Equation 3]

D' _{60 ~100} >D' _{0 ~ 40}

In Equation 3, D' _{0 to 40} and D' _{60 to 100} are ionomer layers at a distance away from the bonding surface between the second ionomer layer and the support in the thickness direction of the support (dotted area L3 or L4 ionomer layer in FIG. 2). Part) refers to the content (% by weight) of the radical scavenger in the total weight of the radical scavenger, based on 100% of the end distance of the second ionomer layer farthest from the bonding surface between the first ionomer layer and the support. Looking at, D' _{0 ~ 40} means the content (%) of the radical scavenger in the second ionomer layer located at a distance of 10% to 40% in the direction of the end of the second ionomer layer from the bonding surface, D' _{60 to 100} means the content (%) of the radical scavenger in the second ionomer layer located at a distance of 60% to 90% in the direction of the end of the second ionomer layer from the bonding surface.

[Radical Scavenger ]

The radical scavenger used for each of the first ionomer layer and/or the second ionomer layer of the PEMFC composite electrolyte membrane of the present invention may be the same as or different from each other, and the radical scavenger may be an inorganic radical scavenger and an organic radical. It may include one selected from among radical scavengers, and preferably, a reusable inorganic radical scavenger is used.

As the organic radical scavenger, an organic radical scavenger generally used in the art may be used, and preferably, a phenolic radical scavenger and a thiopropionate radical scavenger and a phosphorus radical scavenger It can be used by mixing a single species selected from or two or more.

The phenolic radical scavenger includes thio diethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate, octadecyl-3-(3,5-di-t -Butyl-4-hydroxy phenyl) propionate, isotridecyl-3-(3,5-di-t-butyl-4hydroxyphenyl) propionate, and isooctyl-3-(3,5- Di-t-butyl-4-hydroxy phenyl) propionate. In addition, the thiopropionate-based radical scavengers include pentaerythritol tetrakis-(3-dodecyl thio propionate), didodecyl thio propionate, ditetradecyl thio propionate, and dioctadecyl It may include one or more selected from thio propionate. The phosphorus radical scavenger may include tris(2,4-di-t-butylphenyl)phosphate.

In addition, as the inorganic radical scavenger, an inorganic radical scavenger generally used in the art may be used, preferably Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, An oxide of a metal containing at least one selected from Group 11 elements, Zn, Al, La, and Ce can be used singly or in combination, more preferably cerium oxide, zirconium oxide, manganese oxide, aluminum oxide, vanadium oxide , Metal oxides containing cerium and zinc may be discontinued or mixed. More specifically, CeO, CeO ₂ , Ce ₂ O ₃ , CePO ₄ , Ce ₃ (PO ₄ ) ₄ , Zn ₃ (PO ₄ ) ₂ , ZnO, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , ZrO ₂ , MoO _{3 ,} CrPO ₄ , AlPO ₄ and FePO ₄ , may include one or more selected from.

In addition, as an inorganic radical scavenger, a CeZnO metal oxide may be included, and the CeZnO metal oxide including cerium and zinc has a crystal structure composed of cerium (Ce) atoms, zinc (Zn) atoms, and oxygen (O) atoms. Branches are metal oxide particles (hereinafter referred to as CeZnO metal oxides), and may have a crystal structure in which a part of Zn atoms is substituted with Ce atoms in a ZnO crystal structure having a wurtzite crystal structure. The CeZnO metal oxide may include Ce 12 to 91 wt%, Zn 7 to 84.5 wt%, and the balance of O, preferably Ce 13.40 to 89.20 wt%, Zn 7.55 to 88.20 wt% and the balance of O You may. And, it may further include other inevitable impurities. In addition, the CeZnO metal oxide may be 200 nm or less, preferably 160 nm or less, more preferably 45 to 160 nm when analyzing particle size (D50) with a nano particle size analyzer of a DLS (Dynamic Light Scattering) method. This, Ce-Zn-O metal oxide is to permanently remove the capture radicals such as HO · and / or generated during HOO · Ce ^{+ 3} ion is Ce and / or Ce ^{4 +} a fuel cell operation.

In the inorganic radical scavenger, the CeZnO metal oxide is mixed with a [Zn(OH) ₄ ] ^2- containing solution and a reduction reaction is performed to form CeZnO metal oxide particles having a ZnO crystal structure doped with cerium ions. It can be prepared by ordering. Here, “Ce ion-doped ZnO crystal structure” means that a crystal structure in which a part of Zn atoms is substituted with a Ce atom is newly formed in a ZnO crystal structure having a wurtzite crystal structure.

When explaining a method for manufacturing this, a Zn precursor solution is prepared by dissolving a Zn precursor in alcohol, and then heating the Zn precursor solution; [Zn(OH) ₄ ] Two steps to prepare a 2 ^- containing solution; [Zn (OH) _4] 3 steps of performing a ^2-containing solution is mixed and the reduction reaction of Ce precursor solution to form a CeZnO metal oxide particles having a ZnO crystal structure Ce ion-doped; Four steps of recovering and washing the CeZnO metal oxide particles; And 5 steps of drying the washed CeZnO metal oxide particles; a radical scavenger for PEMFC may be prepared by performing a process including the.

The temperature rise in step 1 can be carried out by gradually heating the Zn precursor solution to 40°C to 70°C, preferably to 55°C to 70°C.

The Zn precursor in the first stage is zinc acetate, zinc nitrate, zinc sulfate, zinc chloride, zinc bromide, zinc phosphate, zinc iodide (Zinc iodide), zinc cyanide, zinc methoxide, zinc acrylate, zinc fluoride, zinc fluoride and zinc phosphide It may, and preferably, may include at least one selected from zinc acetate, zinc nitrate, and zinc sulfate.

The alcohol in the first step may include one or more selected from methanol, ethanol, propanol and butanol, and preferably methanol.

The Zn precursor solution of step 1 may be used in which the Zn precursor is dissolved in alcohol at a concentration of 0.01M to 5M, preferably 0.05M to 2M. At this time, if the concentration of the Zn precursor is less than 0.01M, synthesis may be performed [Zn (OH) ₄ ] There may be a problem that it is difficult to convert to ^-2 , and if it exceeds 5M, there may be a problem that it is difficult to dissolve in an alcohol solvent.

Next, in step 2, the [Zn(OH) ₄ ] ^2- containing solution is prepared by adding, stirring, and reacting an ionizing agent in the Zn precursor solution. When the ionizing agent is added to the Zn precursor solution, ZnO is formed, and the ionizing agent is formed. If is continuously added, the pH increases and ZnO changes to [Zn(OH) ₄ ] ^2- and the mixed solution changes to a transparent color.

When the ionizing agent is added, the Zn precursor solution is preferably 40°C to 70°C, preferably 55°C to 65°C, and if the Zn precursor solution is less than 40°C, [Zn(OH) ₄ ] ^2- is not produced or There may be a problem that only a very small amount is generated, and if it exceeds 70°C, the solvent may have a problem of boiling, so it is good to add, agitate, and react with an ionizing agent in the Zn precursor solution having the above temperature.

In addition, the input amount of the ionizing agent is not particularly limited, but the pH of the mixed solution of the Zn precursor solution and the ionizing agent is 6 to 14, preferably until the pH is 8 to 12, more preferably the pH is 8 to 10. It is good to mix and react by adding the ionizing agent dropwise until it is possible. It varies depending on the Zn ion content in the Zn precursor solution, but when the Zn ion content is low, the mixed solution turns to a transparent color from pH 6 or higher.

The ionizing agent is a basic solution, and includes a solution dissolved in a lower alcohol in a concentration of 0.05M to 5M hydroxide, preferably 0.5M to 2M concentration. At this time, if the hydroxide concentration is less than 0.05M, it may be difficult to convert to [Zn(OH) ₄ ] ^-2 during synthesis, and if it exceeds 5M, there may be a problem that it is not soluble in alcohol solvent. It is good to use what is dissolved in alcohol.

And, the hydroxide is KOH, NaOH, Ca (OH) ₂ , Ba(OH) ₂ , Mg(OH) ₂ , NaHCO ₃ , Al(OH) ₃ and may include one or more selected from NH ₃ , preferably one of KOH, NaOH, and Ca(OH) ₂ The above may more preferably contain KOH.

In addition, the lower alcohol used in the preparation of the ionizing agent may include one or more selected from methanol, ethanol, propanol and butanol, preferably the same alcohol used in the preparation of the Zn precursor solution in one step, , More preferably, methanol can be used.

Next, in step 3, [Zn(OH) ₄ ] ^2- containing solution and Ce precursor aqueous solution are mixed and reduced in a 1:0.1 to 10 volume ratio, preferably 1:0.5 to 2 volume ratio, and cerium ions are generated. This is a process of forming CeZnO metal oxide particles having a doped ZnO crystal structure. At this time, if the amount of Ce precursor solution used is less than 1:0.1 by volume ratio, there may be a problem in that the content of Ce in the CeZnO metal oxide particles as a reaction product is small, so that radical removal effect of the prepared CeZnO metal oxide particles, that is, an antioxidant effect may be inferior. When the amount of the solution used exceeds 1:10 by volume, the Ce content in the CeZnO metal oxide particles, which are reaction products, is too high, and thus dispersion stability in the electrolyte is poor, which may cause precipitation. [Zn(OH) ₄ ] When the ^2- containing solution and the Ce precursor aqueous solution are mixed, [Zn(OH) ₄ ] ^2- is converted to ZnO, wherein Ce ions dissolved in water (Ce ^{3 +} and/or Ce ⁴ Some of the ⁺ ) are mixed with the ZnO particles, and only the cations are mixed because the OH ^- ions attract Ce ^{3 +} and/or Ce ^{4 +} .

The Ce precursor aqueous solution includes an aqueous solution in which a cerium precursor is dissolved in water, preferably DI-water, in an amount of 0.01M to 5M, preferably 0.05M to 2M. At this time, if the cerium precursor concentration is less than 0.05M, the Ce content in the CeZnO metal oxide particles is small, and thus the radical removal effect of the prepared CeZnO metal oxide particles, that is, the antioxidant effect may be inferior, and if the cerium precursor concentration exceeds 5M Since the Ce content in the CeZnO metal oxide particles, which are reaction products, is too high, dispersion stability in the electrolyte is poor, which may cause a problem of precipitation.

In addition, the cerium precursors are cerium nitrate hexahydrate, cerium(IV) hydroxide, cerium(III) bromide, cerium(III) oxalate, and cerium(IV) sulfate. sulfate), cerium(III) chloride, cerium(III) iodide, cerium(III) fluoride, cerium acetylacetonate, cerium(III) acetylacetonate, and cerium ammonium nitrate ( Ammonium cerium (IV) nitrate), and may preferably include one or more selected from cerium nitrate, cerium sulfate, and cerium chloride.

And, in step 3, it is good to perform the mixing and reduction reaction of the [Zn(OH) ₄ ] ^2- containing solution and the Ce precursor aqueous solution under 0°C to 70°C, preferably at 40°C to 65°C. If a is less than 0 ℃ can not be a substitution reaction of Ce atoms in the crystal structure in a Zn atom due to Ce ion doped well achieved, when the reaction temperature exceeds _{70 ℃ [Zn (OH) 4} ] , some of the alcohol ² As the evaporation may cause a problem that the reaction is non-uniform, it is preferable to perform mixing and reaction under the temperature range.

Next, step 4 is a process of recovering CeZnO metal oxide particles from the reaction product of step 3, and washing them to improve the final CeZnO metal oxide particles, a radical scavenger, and the recovery is a general method used in the art. It can be carried out through, for example, by filtering it can be recovered the reaction product CeZnO metal oxide particles from the reaction solution. In addition, the washing may be performed through a general method used in the art, and is not particularly limited.

And, the drying in step 5 may be performed through a general method used in the art, and for example, 20 to 90° C. to 120° C., preferably 95° C. to 110° C. for washed CeZnO metal oxide particles. Heat drying may be performed for about 36 hours.

In addition, in order to increase the crystallinity of the heat-dried metal oxide particles, a calcination process may be additionally performed. For a preferred example, calcination is performed at 1,500° C. or less, preferably at 1,000° C. to 1,450° C. It can be done.

[ PTFE  Porous support]

Next, the support layer, which is one of the configurations of the composite electrolyte membrane of the present invention, may use a general porous support used in the art, and preferably a PTFE porous support having specific properties prepared by the following manufacturing method. .

The PTFE porous support is a 1-1 step of preparing a paste by mixing and stirring the PTFE powder and lubricant; 1-2 steps of aging the paste; Steps 1-3 for producing an unbaked tape by extruding and rolling the aged paste; After drying the green tape, steps 1-4 to remove the liquid lubricant; Step 1-5 of uniaxially stretching the unbaked tape from which the lubricant has been removed; Steps 1-6 of biaxially stretching the uniaxially stretched micro tape; And 1-7 steps of firing; can be prepared by performing a process comprising.

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

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

Next, aging in steps 1-2 is a pre-forming process, and the paste can be aged for 12 to 24 hours at a temperature of 30°C to 70°C, preferably 16 to 20 at a temperature of 35°C to 60°C Can ripen for an hour. When the aging temperature is less than 35°C or the aging time is less than 12 hours, the lubricant coating on the PTFE powder surface becomes uneven, and thus the stretching uniformity of the PTFE sheet during biaxial stretching described later may be limited. In addition, when the aging temperature exceeds 70°C or the aging time exceeds 24 hours, there may be a problem that the support pore size after the biaxial stretching process is too small due to the evaporation of the lubricant.

Next, the extruding in steps 1-3 is performed by compressing the aged paste in a compressor to prepare a PTFE block, and then pressing the PTFE block at a pressure of 0.069 to 0.200 Ton/cm ² , preferably 0.090 to 0.175 Ton/cm ² It can be carried out by extrusion under pressure. At this time, the pressure extrusion pressure is 0.069 Ton / cm ² If it is less than the pore size of the support may be increased, the strength of the support may be weakened, and if it exceeds 0.200 Ton/cm ² , there may be a problem that the support pore size after the biaxial stretching process is reduced.

In addition, the rolling of steps 1-3 may be performed by a calendering process under 50 to 100° C. with a hydraulic pressure of 5 to 10 MPa. At this time, when the hydraulic pressure is less than 5MPa, the pore size of the support may be increased, so that the strength of the support may be weakened, and when it exceeds 10MPa, the pore size of the support may be reduced.

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

Next, the uniaxial stretching in steps 1-5 is a process of stretching the unfinished tape from which the lubricant has been removed in the longitudinal direction. When transporting through the roller, uniaxial stretching is performed using a speed difference between the rollers. In addition, the uniaxial stretching stretches the non-lubricated unfinished tape 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. It is good to do. At this time, if the uniaxial stretching ratio is less than 3 times, sufficient mechanical properties cannot be secured. If the uniaxial stretching ratio exceeds 10 times, mechanical properties may decrease, and the pores of the support may be too large.

And, the uniaxial stretching is performed at a stretching temperature of 260°C to 350°C and a drawing speed of 6 to 12 M/min, preferably a drawing temperature of 270°C to 330°C and a drawing rate of 8 to 11.5 M/min It is preferable, and if the stretching temperature during uniaxial stretching is less than 260°C, or when the stretching speed is less than 6 M/min, there may be a problem that a heat is applied to the drying sheet and a firing section may occur, and the stretching temperature during uniaxial stretching. If it exceeds 350°C, or if the stretching speed exceeds 12 M/min, slip may occur during the uniaxial stretching process, and there may be a problem that thickness uniformity is lowered.

Next, the biaxial stretching in steps 1-6 is stretched in the width direction (direction perpendicular to the uniaxial stretching) of the uniaxially stretched unstretched tape, and stretched by extending the width in the transverse direction while the end is fixed. can do. However, the present invention 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 in the width direction 15 to 50 times, preferably 25 to 45 times, more 28 to 45 times, 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, there is no improvement in mechanical properties, and there is a problem that the uniformity of properties in the longitudinal direction and/or the width direction decreases. Since it is possible, it is preferable to perform stretching within the above range.

Further, biaxial stretching is performed at a stretching rate of 10 to 20 M/min under a stretching temperature of 150°C to 260°C, preferably under a stretching rate of 11 to 18 M/min under a stretching temperature of 200°C to 250°C. It is preferred to do this, and if the biaxial stretching temperature is less than 150°C 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°C, or If the elongation speed exceeds 20 M/min, a microscopic section may occur, which may cause a problem of deterioration in physical properties.

Next, the firing in steps 1-7 is carried out at a speed of 10 to 18 M/min on the conveyor belt, preferably at a speed of 13 to 17 M/min, while moving the stretched porous support at 350°C to 450°C, preferably For example, a temperature of 380°C to 440°C, and more preferably 400°C to 435°C, may be performed by adding a temperature, through which the stretching ratio can be fixed and strength improvement effect can be sought. When 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 that the physical properties of the support are lowered due to a decrease in the number of fibrils due to undercalcination.

The PTFE porous support prepared by performing the 1-7 steps process has an elongation ratio (or aspect ratio) of 1-axis direction (longitudinal direction) and 2-axis direction (width direction) of 1:3.00 to 8.5, preferably 1: 4.0 to 7.0 , More preferably 1: 4.00 to 5.50, more preferably 1: 4.20 to 5.00, the axial and biaxial stretching ratios (or aspect ratios) of the above range is high mechanical properties, support It is desirable in terms of securing the proper pore size and securing the proper current flow.

The prepared porous support 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 support of the present invention may have an average porosity of 60% to 90%, more preferably 60% to 79.6%.

At this time, when the average pore size of the porous support is less than 0.080 μm or the porosity is less than 60%, when the electrolyte is impregnated to prepare the electrolyte membrane using the support, the degree of impregnation of the electrolyte in the support may be limited. In addition, when the average pore size exceeds 0.200 μm or the porosity exceeds 90%, the porous support structure may be deformed when impregnated with an electrolyte, and product life may be reduced due to a decrease in dimensional stability.

In addition, the PTFE porous support prepared by the above method may have an average thickness of 5 μm to 25 μm, preferably an average thickness of 5 μm to 20 μm, and more preferably 10 μm to 20 μm.

As described above, the PTFE porous support may satisfy the following Equation 4 when the values of the 1-axis direction modulus and the 2-axis direction modulus are measured according to ASTM D 882.

[Equation 4]

0 ≤ │(1-axis direction modulus-2-axis direction modulus)/(1-axis direction modulus)×100%│ ≤ 54%, preferably 0 ≤ │(1-axis direction modulus-2-axis direction modulus)/(1-axis Direction modulus)×100%│ ≤ 40%, more preferably 1 ≤ │(1-axis direction modulus-2-axis direction modulus)/(1-axis direction modulus)×100%│ ≤ 26%,

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

In addition, the porous support of the present invention may be measured in accordance with ASTM D882, the uniaxial direction (longitudinal) tensile strength of 40 MPa or more and the biaxial direction (width direction) tensile strength of 40 MPa or more, preferably 1 The axial tensile strength may be 50 MPa or more, more preferably, the uniaxial tensile strength may be 54 to 65 Mpa. Further, 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.

The porous support of the present invention prepared by the above-described method having excellent mechanical properties includes steps 1-8 impregnated with the fluorine-based ionomer solution by firing in steps 1-7; And steps 1-9 of drying and heat-treating the impregnated PTFE porous support.

The fluorine-based ionomer solution in steps 1-8 may further include hollow silica, thereby improving moisture absorption of the support to the fluorine-based ionomer solution and preventing volume expansion of the PTFE porous support due to impregnation of the fluorine-based ionomer solution. have.

The fluorine-based ionomer may include one or more selected from Nafion, Flemion, and Aciplex, and more preferably Nafion.

The hollow silica is spherical, and may have an average particle diameter of 10 to 300 nm, more preferably 10 to 100 nm. Here, the particle size means a diameter when the shape of the hollow silica is spherical, and when it is not spherical, it means a maximum distance among linear distances from any one point to another on the surface of the hollow silica. If the average particle diameter of the hollow silica is less than 10 nm, the absorption capacity of the fluorine-based ionomer solution may be limited as the capacity to support the fluorine-based ionomer solution decreases, and the PTFE porous support when the average diameter exceeds 300 nm The amount of the hollow silica impregnated in the pores may be limited.

The hollow portion included in the hollow silica is a space on which the fluorine-based ionomer solution adsorbed and moved through the shell portion is supported. Preferably, the hollow diameter may be 5 to 100 nm, and more preferably 5 to 50 nm. . If the hollow diameter is less than 5 nm, the amount of the fluorine-based ionomer solution supported may be reduced, and if it exceeds 100 nm, the particle size of the hollow silica may increase beyond a desired range or cause collapse of the shell portion. The fluorine-based ionomer solution may contain 0.05 to 5 parts by weight of the hollow silica with respect to 100 parts by weight, and more preferably 1 to 3 parts by weight. When the hollow silica contains less than 0.05 parts by weight based on 100 parts by weight of the fluorine-based ionomer solution, the impregnation effect of the fluorine-based ionomer solution may be insignificant. When applied to the electrode assembly, the flow diagram of the current may be lowered.

In addition, the fluorine-based ionomer solution may further include at least one hygroscopic agent selected from zeolite, titania, zirconia, and montmorillonite.

The drying of steps 1-9 may be performed at a temperature of 60°C to 100°C for 1 to 30 minutes, and heat treatment may be performed at a temperature of 100°C to 200°C for 1 minute to 5 minutes. When the temperature of the drying process is less than 60°C, the liquid retainability of the fluorine-based ionomer solution impregnated in the porous support may be lowered, and when it exceeds 100°C, the electrolyte membrane is manufactured, and the electrolyte membrane and/or the membrane-electrode assembly is prepared. The adhesion with the electrode may be deteriorated. In addition, in the heat treatment process, when the heat treatment temperature is less than 100°C or the time is less than 1 minute, the liquid retention property of the fluorine-based ionomer solution impregnated in the porous support may decrease, and the temperature exceeds 200°C or the heat treatment time is 5 minutes. When exceeded, when the support is adhered to the electrolyte membrane, adhesion to the electrolyte membrane may be deteriorated.

In the heat-treated porous support in step 9, the volume of the closed pores may be 90% by volume or more with respect to the total pore volume.

The PEMFC composite electrolyte membrane of the present invention may have a weight variation coefficient (CV1) value of relational expression 1 below 40% or more, preferably 45 to 300%, more preferably 60% to 140%.

[Relationship 1]

Weight coefficient of variation (CV1,%) = │(thickness of porous support after electrolyte treatment-weight of porous support before electrolyte treatment) / (weight of porous support before electrolyte treatment)│ × 100

The weight fluctuation coefficient is formed as an electrolyte membrane coated on the surface of the porous support before and after impregnation of the fluorine-based ionomer solution, which is an electrolyte, in the porous support, and is one of the indicators for measuring the weight change due to impregnation inside the pores of the porous support. , It can be seen that the larger the value, the greater the impregnation amount of the fluorine-based ionomer impregnated in the porous support.

As described above, the composite electrolyte membrane according to the present invention can be seen that the impregnation amount of the electrolyte impregnated in the porous support is large by satisfying the weight fluctuation coefficient of 40% or more. High electrolyte impregnation.

In addition, the PEMFC fuel cell electrolyte membrane of the present invention manufactured using the PEMFC porous support has an effect of increasing tensile strength and modulus, and the fuel cell electrolyte membrane of the present invention is measured in accordance with ASTM D 882, in one axial direction (longitudinal direction ) The modulus may be 50 MPa or more, preferably, the uniaxial modulus may be 55 MPa or more, and more preferably, the uniaxial modulus may be 55 to 100 Mpa. In addition, the biaxial direction (width direction) modulus may be 50 MPa or more, preferably, the biaxial direction (width direction) modulus may be 53 Mpa or more, and more preferably 55 to 90 Mpa.

In addition, the PEMFC fuel cell electrolyte membrane of the present invention may have a tensile strength of 45 MPa or higher in the uniaxial direction (longitudinal direction) and 45 MPa or higher in the biaxial direction (width direction) when measured according to ASTM D882. For example, the tensile strength in the axial direction may be 55 MPa or more, and more preferably, the tensile strength in the axial direction may be 56 to 90 Mpa. In addition, preferably, the biaxial tensile strength may be 50 to 85 Mpa, more preferably, the biaxial tensile strength may be 50 to 78 Mpa.

In addition, the PEMFC fuel cell electrolyte membrane of the present invention has a simplified structure compared to a conventional fuel cell electrolyte membrane, and can improve interfacial properties when bonded to an electrode. In addition, since the thickness of the support can be designed to be thin, as the thickness of the electrolyte membrane becomes thin, hydrogen ion transfer delay can be prevented, and there is an effect of improving the performance of the fuel cell.

Membrane-electrode assembly according to an embodiment of the present invention, as shown in a schematic cross-sectional view in Figure 8, preparing the above-described composite electrolyte membrane for PEMFC 10, and catalyst layers (22) on both sides of the electrolyte membrane for the fuel cell , 22'), gas diffusion layer (21, 21')? It may be manufactured by performing a process including the step of bonding the electrode comprising the electrode base (23, 23').

Referring to FIG. 8, the membrane-electrode assembly according to an embodiment of the present invention includes an anode (anode, anode, 20) and a cathode (cathode, reduction) positioned opposite each other with the fuel cell electrolyte membrane 10 interposed therebetween. Electrode, 20'). At this time, the anode 20 and the cathode 20' include gas diffusion layers 21 and 21', catalyst layers 22 and 22', and electrode substrates 23 and 23', respectively.

The anode 20 may include a gas diffusion layer 21 and an oxidation catalyst layer 22. The gas diffusion layer 21 may be provided to prevent sudden diffusion of fuel injected into the fuel cell and to prevent a decrease in ion conductivity. The gas diffusion layer 21 may adjust the diffusion rate of fuel through heat treatment or electrochemical treatment. The gas diffusion layer 21 may be carbon fiber or carbon paper. Here, the fuel may be a liquid fuel such as formic acid solution, methanol, formaldehyde, or ethanol.

The oxidation catalyst layer 22 is a layer into which the catalyst is introduced, and may include a conductive support and an ion conductive binder (not shown). In addition to this, the oxidation catalyst layer 22 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 oxidation catalyst layer 22 may be formed using an electroplating method, a spray method, a painting method, a doctor blade method, or a transfer method.

The cathode 20' may include a gas diffusion layer 21' and a reduction catalyst layer 22'. The gas diffusion layer 21 ′ may be provided to prevent sudden diffusion of gas injected into the cathode 20 ′ and to uniformly disperse the gas injected into the cathode 20 ′. The gas diffusion layer (21') may be carbon paper or carbon fiber.

The reduction catalyst layer 22' is a layer into which a catalyst is introduced, and may include a conductive support and an ion conductive binder (not shown). In addition, the reduction catalyst layer 22' 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 reduction catalyst layer 22' may be formed using an electroplating method, a spray method, a painting method, a doctor blade method, or a transfer method.

The membrane-electrode assembly may be formed by disposing the oxide electrode 20, the composite electrolyte membrane 10 for a fuel cell, and the reducing electrode 20', and then fastening them or compressing them at high temperature and high pressure.

The step of bonding the electrodes 20 and 20' to both surfaces of the PEMFC composite electrolyte membrane 10 is first applied to a gas diffusion layer forming material on one surface of the fuel cell electrolyte membrane 10 to form a gas diffusion layer (21, 21). ').

The gas diffusion layers 21 and 21' serve as a current conductor between the composite electrolyte membrane 10 for PEMFC and the catalyst layers 22 and 22', and serve as a passage for gas as a reactant and water as a product. Accordingly, the gas diffusion layers 21 and 21' may have a porous structure having a porosity of 20% to 90% so that the gas can pass well. The thickness of the gas diffusion layers 21 and 21' may be appropriately adopted as necessary, and may be, for example, 100 to 400 μm. When the thickness of the gas diffusion layers 21 and 21' is 100 µm or less, the electrical contact resistance between the catalyst layer and the electrode substrate becomes large, and the structure may become unstable by compression. In addition, when the thickness of the gas diffusion layers 21 and 21' exceeds 400 μm, movement of the reactant gas may be difficult.

The gas diffusion layers 21 and 21' may be formed of a carbon-based material and a fluorine-based resin. Carbon-based materials include graphite, carbon black, acetylene black, denka black, kecheon black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon nanoring, carbon nanowire, fullerene (C60) And it may include one or more selected from the group consisting of super P, but is not limited thereto. Further, examples of the fluorine-based resin include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose acetate, copolymer of polyvinylidene fluoride-hexafluoropropylene, or styrene-butadiene high part (SBR). It may include one or more selected from the group consisting of.

Next, catalyst layers 22 and 22' are formed on the gas diffusion layers 21 and 21'.

The catalyst layers 22 and 22' may be formed by applying a catalyst layer forming material on the gas diffusion layers 21 and 21'.

The catalyst layer-forming material may be a metal catalyst or a metal catalyst supported on a carbon-based support. As the metal catalyst, 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. In addition, the carbon-based support is graphite (graphite), carbon black, acetylene black, denka black, kecheon black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon nanoring, carbon nano It may include at least one selected from the group consisting of wire, fullerene and super P.

The electrode substrates 23 and 23' may use a conductive substrate selected from the group consisting of carbon paper, carbon cloth, and carbon felt, but are not limited thereto, and a cathode electrode material applicable to a polymer electrolyte fuel cell or All anode electrode materials can be used. The electrode substrate may be formed through a conventional deposition method, and after forming the catalyst layers 22 and 22' on the electrode substrate 23 and 23', the catalyst layer on the gas diffusion layers 21 and 21' (22, 22') and the gas diffusion layer (21, 21') may be formed by placing the contact.

On the other hand, the fuel cell according to an embodiment of the present invention at least one electricity generating unit for generating electrical energy through the oxidation reaction of the fuel and the reduction reaction of the oxidizing agent, and a fuel supply unit for supplying the aforementioned fuel to the electricity generating unit And an oxidant pore portion for supplying an oxidant to the electricity generating portion.

The membrane-electrode assembly may include one or more, and a separator for supplying fuel and an oxidizing agent is disposed at both ends of the membrane-electrode assembly to constitute an electric generator. At least one of these electricity generating units may be collected to form a stack.

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

Hereinafter, preferred examples are provided to help understanding of the present invention. However, the following examples are only to aid the understanding of the present invention, and the present invention is not limited by the following experimental examples.

[ Example ]

Preparation example 1-1: PTFE  Preparation of porous support

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

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

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

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

Next, while transferring the unbaked tape to the conveyor belt at a rate of 3M/min, the lubricant was removed by drying by applying heat of 180°C.

Next, uniaxial stretching (longitudinal stretching) of the unfinished tape from which the lubricant was removed was performed at 6.5 times under the stretching temperature of 280° C. and the stretching speed of 10 M/min.

Next, the uniaxially stretched micro tape was subjected to biaxial stretching (stretching in the width direction) 30 times under a stretching temperature of 250° C. and a stretching rate of 10 M/min, to prepare a porous support.

Next, the uniaxial and biaxially stretched porous support was calcined by applying a temperature of 420°C at a rate of 15 M/min on a conveyor belt to prepare a PTFE porous support having an average thickness of 14 µm and an average pore size of 0.114 µm.

Preparation example 1-2 ~ Preparation example 1-3 and Comparative Preparation  1-1 ~ Comparative Preparation  1-2

It was carried out in the same manner as in Preparation Example 1-1, and the porous support prepared by uniaxially and biaxially stretching in Example 1 was prepared by preparing the PTFE porous support by changing the firing temperature as shown in Table 1 below, respectively. -2 to 1-3 and Comparative Preparation Examples 1-1 to 1-2 were performed, respectively.

Preparation example  1-4 ~ Preparation example  1-6 and Comparative Preparation  1-3 ~ Comparative Preparation  1-6

It was carried out in the same manner as in Preparation Example 1-1, by preparing the PTFE porous support by varying the temperature at the time of uniaxial stretching or at the time of biaxial stretching as shown in Table 1 below, Preparation Examples 1-4 to 1-6 And Comparative Preparation Examples 1-3 to 1-6, respectively.

Preparation example 1-7 ~ Preparation example  1-10 and Comparative Preparation  1-7 ~ Comparative Preparation  1-10

It was carried out in the same manner as in Preparation Example 1-1, by preparing the PTFE porous support by varying the stretching speed during uniaxial stretching or the stretching speed during biaxial stretching as shown in Table 1 below, Preparation Examples 1-7 to 1 -10 and Comparative Preparation Examples 1-7 to 1-10 were performed, respectively.

Preparation example  1-11 ~ Preparation example 1-14 and Comparative Preparation 1-11 ~ Comparative Preparation 1-15

To prepare a PTFE porous support in the same manner as in Preparation Example 1-1, uniaxial and biaxial stretching were performed under the conditions shown in Tables 1 and 2, respectively.

division Firing
Temperature
(℃) 1-axis stretching temperature
(℃) Biaxial stretching temperature
(℃) 1-axis stretching speed
(M/min) 2-axis stretching speed
(M/min) 1-axis stretching ratio
(Longitudinal direction) Biaxial stretching ratio
(Width direction) 1-axis and 2-axis stretching ratio
(Support body stretch aspect ratio) Support
Average
thickness
(㎛) Preparation Example 1-1 420 280 250 10 10 6.5 30 1:4.62 14㎛ Preparation Example 1-2 440 280 250 10 10 6.5 30 1:4.62 12㎛ Preparation Example 1-3 380 280 250 10 10 6.5 30 1:4.62 17㎛ Preparation Example 1-4 420 260 250 10 10 6.5 30 1:4.62 16㎛ Preparation Example 1-5 420 330 250 10 10 6.5 30 1:4.62 13㎛ Preparation Example 1-6 420 280 260 10 10 6.5 30 1:4.62 14㎛ Preparation Example 1-7 420 280 250 8 10 6.5 30 1:4.62 14㎛ Preparation Example 1-8 420 280 250 11.5 10 6.5 30 1:4.62 14㎛ Preparation Example 1-9 420 280 250 10 15 6.5 30 1:4.62 16㎛ Preparation Example 1-10 420 280 250 10 18 6.5 30 1:4.62 16㎛ Preparation Example 1-11 420 280 250 10 10 7 30 1:4.29 12㎛ Preparation Example 1-12 420 280 250 10 10 8 36 1:4.50 10㎛ Preparation Example 1-13 420 280 250 10 10 8 32 1:4.00 11㎛ Preparation Example 1-14 420 280 250 10 10 6.5 45 1:6.92 10㎛

division Firing
Temperature
(℃) 1-axis stretching temperature
(℃) Biaxial stretching temperature
(℃) 1-axis stretching speed
(M/min) 2-axis stretching speed
(M/min) 1-axis stretching ratio
(Longitudinal direction) Biaxial stretching ratio
(Width direction) 1-axis and 2-axis stretching ratio
(Support body stretch aspect ratio) Support
Average
thickness
(㎛) Comparative Preparation Example 1-1 335 280 250 10 10 6.5 30 1:4.62 18㎛ Comparative Preparation Example 1-2 460 280 250 10 10 6.5 30 1:4.62 9㎛ Comparative Preparation Example 1-3 420 240 250 10 10 6.5 30 1:4.62 15㎛ Comparative Preparation Example 1-4 420 365 250 10 10 6.5 30 1:4.62 11㎛ Comparative Preparation Example 1-5 420 280 140 10 10 6.5 30 1:4.62 17㎛ Comparative Preparation Example 1-6 420 280 290 10 10 6.5 30 1:4.62 13㎛ Comparative Preparation Example 1-7 420 280 250 5.5 10 6.5 30 1:4.62 12㎛ Comparative Preparation Example 1-8 420 280 250 14 10 6.5 30 1:4.62 18㎛ Comparative Preparation Example 1-9 420 280 250 10 8 6.5 30 1:4.62 11㎛ Comparative Preparation Example 1-10 420 280 250 10 22 6.5 30 1:4.62 18㎛ Comparative Preparation Example 1-11 420 280 250 10 10 2.5 18 1:7.20 27㎛ Comparative Preparation Example 1-12 420 280 250 10 10 2.5 20 1:8.00 24㎛ Comparative Preparation Example 1-13 420 280 250 10 10 8 22 1:2.75 16㎛ Comparative Preparation Example 1-14 420 280 250 10 10 6.5 14 1:2.15 25㎛ Comparative Preparation Example 1-15 420 280 250 10 10 6.5 51 1:7.85 7㎛

Experimental Example  One : PTFE Measurement of mechanical properties of porous support

After measuring the average pore size, porosity, tensile strength and modulus of each of the porous supports prepared in the Preparation Examples and Comparative Preparation Examples, the results are shown in Tables 3 and 4 below.

The average pore size and porosity were measured in accordance with ASTM F316-03, the pressure was 0 to 70 psi, the solvent was a galwick, and was measured by a dry up/wet up method (capillary perforation, capillary flow) porometer).

And, the tensile strength and modulus according to ASTM D 882 method, after manufacturing a straight specimen (width 10 mm, length 100 mm), the test speed of 500 mm / min, the initial grip distance (universal universal testing machine) at 500 mm conditions test machine).

division Average pore size (㎛) Porosity (%) Preparation Example 1-1 0.124 71.0 Preparation Example 1-2 0.152 78.7 Preparation Example 1-3 0.093 62.3 Preparation Example 1-4 0.117 69.7 Preparation Example 1-5 0.144 76.5 Preparation Example 1-6 0.131 72.1 Preparation Example 1-7 0.147 77.0 Preparation Example 1-8 0.115 68.8 Preparation Example 1-9 0.098 65.1 Preparation Example 1-10 0.083 61.2 Preparation Example 1-11 0.143 76.3 Preparation Example 1-12 0.155 79.6 Preparation Example 1-13 0.143 76.0 Preparation Example 1-14 0.153 77.7 Comparative Preparation Example 1-1 0.073 55.2 Comparative Preparation Example 1-2 0.260 90.4 Comparative Preparation Example 1-3 0.077 57.4 Comparative Preparation Example 1-4 0.215 87.2 Comparative Preparation Example 1-5 0.069 51.5 Comparative Preparation Example 1-6 0.233 88.0 Comparative Preparation Example 1-7 0.216 86.9 Comparative Preparation Example 1-8 0.073 53.1 Comparative Preparation Example 1-9 0.209 87.0 Comparative Preparation Example 1-10 0.077 52.9 Comparative Preparation Example 1-11 0.183 81.3 Comparative Preparation Example 1-12 0.196 84.2 Comparative Preparation Example 1-13 0.163 80.5 Comparative Preparation Example 1-14 0.165 81.7 Comparative Preparation Example 1-15 0.213 90.5

division Tensile strength (Mpa) Modulus (Mpa) Difference between 1-axis and 2-axis modulus values (%) ⁽¹⁾ 1 axis
(Longitudinal direction) 2-axis
(Width direction) 1 axis
(Longitudinal direction) 2-axis
(Width direction) Preparation Example 1-1 51 52 50 53 6.00% Preparation Example 1-2 48 50 51 49 3.92% Preparation Example 1-3 64 68 66 65 1.52% Preparation Example 1-4 58 54 60 59 1.67% Preparation Example 1-5 47 44 50 46 8.00% Preparation Example 1-6 53 50 50 53 6.00% Preparation Example 1-7 47 46 48 50 4.17% Preparation Example 1-8 54 58 53 55 3.77% Preparation Example 1-9 64 61 66 63 4.55% Preparation Example 1-10 68 63 68 65 4.41% Preparation Example 1-11 63 49 61 53 13.11% Preparation Example 1-12 62 57 60 55 8.33% Preparation Example 1-13 65 53 66 54 18.18% Preparation Example 1-14 47 63 50 61 22.00% Comparative Preparation Example 1-1 78 71 75 73 2.67% Comparative Preparation Example 1-2 41 37 39 41 5.13% Comparative Preparation Example 1-3 73 69 71 65 8.45% Comparative Preparation Example 1-4 47 45 45 41 8.89% Comparative Preparation Example 1-5 77 79 81 85 4.94% Comparative Preparation Example 1-6 42 46 41 46 12.20% Comparative Preparation Example 1-7 37 33 40 36 10.00% Comparative Preparation Example 1-8 69 74 71 77 8.45% Comparative Preparation Example 1-9 41 43 42 43 2.38% Comparative Preparation Example 1-10 66 70 67 69 2.99% Comparative Preparation Example 1-11 27 43 31 44 41.94% Comparative Preparation Example 1-12 22 47 28 45 60.71% Comparative Preparation Example 1-13 81 23 78 26 66.67% Comparative Preparation Example 1-14 53 27 51 32 37.25% Comparative Preparation Example 1-15 38 63 37 66 78.38% (1) Difference between 1-axis and 2-axis modulus values = │(1-axis modulus-2-axis modulus)/(1-axis modulus)ⅹ100%│

Referring to Table 3, prepared in Example 1 - 1 to 1 - 14 of the support has an average pore size of 0.08 ~ 0.20㎛, it was confirmed that it has a porosity of 60% to 80% range. On the other hand, Comparative Preparation Examples 1-1 and Comparative Preparation Examples 1 - 3 and Comparative Preparation Examples 1 - 5 and Comparative Preparation Example 1 and under the case of 8, the average pore size is 0.08㎛ and had a low porosity of less than 60%. In Comparative Preparation Examples 1 - 4 and Comparative Preparation Examples 1 to 6 and Comparative Preparation Examples 1 - 7 and Comparative Preparation Examples 1 - 9 and Comparative Preparation Examples 1 - 15 have an average pore size exceeded 0.20㎛.

Referring to Table 4, prepared in Example 1 - 1 to 1 - For 14, the tensile strength was a uniaxial and biaxial all over 40 Mpa, the modulus was still more than 40 Mpa both uniaxial and biaxial.

In contrast, in Comparative Preparation Example 12 was biaxially tensile strength and modulus are low, the first axis is less than 40 Mpa, in Comparative Preparation Examples 1 - 11, Comparative Preparation Examples 1 - 12 and Comparative Preparation Examples 1 - 15 In the case of 1 The results showed that the axial tensile strength and uniaxial modulus were lower than 40 Mpa.

In Comparative Preparation Examples 1 - 13 and Comparative Preparation Examples 1 - 14 In the case of biaxial tensile strength and biaxial modulus it was lower resulting in less than 40 Mpa.

Experimental Example 2: Electrolytic membrane Tensile strength and Modulus  Measure

Aquivion ^TM electrolyte was applied to one surface of the PTFE porous support prepared in Preparation Example 1-1 using a film applicator, dried at 90° C. for 10 minutes, and the same was applied to the opposite surface of the porous support. After applying the electrolyte, drying was performed at 90° C. for 10 minutes and heat treatment at 150° C. for 10 minutes to prepare an electrolyte membrane having a three-layer structure including a PTFE porous support layer.

Using the porous support of Preparation Example 1-5, Preparation Example 1-10, Preparation Example 1-15, Comparative Preparation Example 1-6 and Comparative Preparation Example 1-9 in the same manner, the PTFE porous support layer was included 3 A layered electrolyte membrane was prepared.

In addition, an electrolyte membrane having a three-layer structure in cross section was prepared in the same manner as in FIG. 1 by using an existing PTFE porous support (2.5 times for uniaxial stretching ratio, 10 times for biaxial stretching ratio, manufacturer: Sang-Apron Tech).

Then, the tensile strength and modulus of the prepared electrolyte membrane were measured according to ASTM D 882, and the results are shown in Table 5 below.

division The tensile strength Modulus 1-axis direction (MD direction, Mpa) 2-axis direction (TD direction, Mpa) 1-axis direction (MD direction, Mpa) 1-axis direction (MD direction, Mpa) Preparation Example 1-1 60 63 63 69 Preparation Example 1-5 58 51 57 55 Preparation Example 1-10 78 71 96 84 Existing PTFE porous support 47 34 35 15 Comparative Preparation Example 1-6 46 49 45 48 Comparative Preparation Example 1-9 45 47 43 46

Looking at the measurement results of the physical properties of Table 5, in the case of the electrolyte membrane prepared using the existing PTFE porous support, compared with the Examples, it showed a result with significantly lower mechanical properties. On the other hand, in the case of the electrolyte membrane prepared using the PTFE porous support of the present invention, the modulus tended to increase significantly.

In addition, in the case of Comparative Examples 1-6 and Comparative Preparation Examples 1-9, in which the amount of electrolyte impregnation in the porous support was high and the weight fluctuation coefficient exceeded 300%, as compared with the Examples, not only the tensile strength of the electrolyte membrane, but also the modulus significantly decreased It was confirmed that there was a problem, and the effect of increasing mechanical properties according to the preparation of the electrolyte membrane using the porous support was very weak. On the other hand, in the case of Preparation Example 1-1, Preparation Example 1-5, and Preparation Example 1-10, compared with the tensile strength and modulus of the porous support, there was an effect of increasing the tensile strength and modulus of the electrolyte membrane.

Preparation example 2-1: PEMFC  Radical Scavenger  Produce

Zn precursor solution was completely dissolved in methanol (purity 99.5%) to prepare a Zn precursor solution. Separately, an ionizing agent was prepared by dissolving 1 M of KOH in methanol. In addition, a Ce precursor solution in which cerium nitrate hexahydrate was dissolved in DI-water in 0.1 M was prepared separately.

Next, after heating 200 ml of the Zn precursor solution to 60° C., the ionizing agent was added dropwise to the heated Zn precursor solution until pH 10. When it started dropwise, it turned white and gradually changed to a clear solution from pH 6. Finally, dropwise addition was terminated to prepare a solution containing [Zn(OH) ₄ ] ^2- .

Next, under 60° C., the Ce precursor solution was mixed and stirred in a [Zn(OH) ₄ ] ^2- containing solution in a 1:1 volume ratio and stirred to perform a reduction reaction to form CeZnO metal oxide particles.

Next, the precipitated by centrifugation to recover the CeZnO metal oxide particles, washed with distilled water, and then dried at 100° C. for 24 hours to finally prepare a PEMFC radical scavenger which is a CeZnO metal oxide particle.

The prepared radical scavenger was measured by SEM, and the measurement image is shown in FIG. 3. Looking at Figure 3 it can be seen that it is composed of fine particles.

Preparation example  2-2 ~ Preparation example 2-8 and Comparative Preparation  2-1 ~ Comparative Preparation 2-5

It was carried out in the same manner as in Preparation Example 2-1, but Preparation Examples 2-2 to 2-3 and Comparative Preparation Examples 2-1 to 2-2 varied the temperature of the Zn precursor solution when the ionizing agent was added dropwise. In addition, Preparation Examples 2-4 to 2-6 and Comparative Preparation Examples 2-3 were performed by varying the termination pH of the ionizing agent. In addition, Preparation Examples 2-7 to 2-8 and Comparative Preparation Examples 2-4 to 2-5 were performed by varying the volume ratio of the [Zn(OH) ₄ ] ^2- containing solution and the Ce precursor solution as shown in Table 6 below. Scavengers were prepared.

division Zn precursor solution temperature Ionizing agent input pH [Zn(OH) ₄ ] ^2- volume solution and Ce precursor solution volume ratio Preparation Example 2-1 60℃ pH 6 1:1 Preparation Example 2-2 50℃ pH 6 1:1 Preparation Example 2-3 70℃ pH 6 1:1 Preparation Example 2-4 65℃ pH 8 1:1 Preparation Example 2-5 65℃ pH 10 1:1 Preparation Example 2-6 65℃ pH 12 1:1 Preparation Example 2-7 65℃ pH 6 1:0.5 Preparation Example 2-8 65℃ pH 6 1:2 Comparative Preparation Example 2-1 35℃ pH 6 1:1 Comparative Preparation Example 2-2 75℃ pH 6 1:1 Comparative Preparation Example 2-3 65℃ pH 5.5 1:1 Comparative Preparation Example 2-4 65℃ pH 6 1:0.05 Comparative Preparation Example 2-5 65℃ pH 6 1:11

Experimental Example 2: EDS measurement

The radical scavengers prepared in the Preparation Examples and Comparative Preparation Examples were measured, and the measurement graphs for Preparation Examples 2-1 are shown in FIG. 4, and the results of the measurement are shown in Table 7 below.

division Ce
(weight%) Zn
(weight%) O
(weight%) Preparation Example 2-1 13.47% by weight 82.80 wt% 3.73% by weight Preparation Example 2-2 13.76% by weight 83.25% by weight 2.99% by weight Preparation Example 2-3 13.86% by weight 83.15% by weight 2.99% by weight Preparation Example 2-4 51.34% by weight 46.31% by weight 2.35% by weight Preparation Example 2-5 70.20% by weight 27.29% by weight 2.51% by weight Preparation Example 2-6 89.11% by weight 8.57% by weight 2.32% by weight Preparation Example 2-7 4.39% by weight 88.09% by weight 7.52 wt% Preparation Example 2-8 90.45% by weight 7.67% by weight 1.88% by weight Comparative Preparation Example 2-1 0 wt% 81.8 wt% 18.2% by weight Comparative Preparation Example 2-2 11.01% by weight 85.23% by weight 3.76% by weight Comparative Preparation Example 2-3 0 wt% 78.5 wt% 21.5 wt% Comparative Preparation Example 2-4 1.06% by weight 86.8% by weight 12.14% by weight Comparative Preparation Example 2-5 88.64% by weight 10.63% by weight 0.73 wt%

Experimental Example  3: CeZnO  Measurement of particle size and dispersion stability of metal oxide particles

After preparing 10 ml of samples before drying the CeZnO metal oxide particles prepared in Preparation Examples 2-1 to 2-8, mixing them to 1% by weight in a Nafion solution, and then using DLS (Dynamic Light Scattering) The particle size (D50) of the CeZnO particles synthesized using a nanoparticle size analyzer (manufacturer: Microtrac, trade name Nanotrac Wave) was measured, and the results are shown in Table 3 below. Along with this, 10 ml of a sample was taken before drying CeO ₂ metal oxide particles (purchased by US Research Nanomaterials, Inc.) used as a conventional radical scavenger, and then mixed to 1% by weight in a Nafion solution, The particle size (D50) of CeO ₂ metal oxide particles was measured using a nanoparticle size analyzer, and the results are shown in Table 8 below.

And, the particle size measurement data measured before and after mixing of CeZnO metal oxide particles and CeO ₂ metal oxide particles of Preparation Example 2-2 with Nafion are shown in FIGS. 5A to 5B and 6A to 6B. 5A is a particle size measurement result of Preparation Example 2-2 before mixing with Nafion, and FIG. 5B is a particle size measurement result of Preparation Example 2-2 after mixing with Nafion. 6A is a particle size measurement result of CeO ₂ metal oxide particles before mixing with Nafion, and FIG. 6B is a particle size measurement result of CeO ₂ metal oxide particles after mixing with Nafion.

In addition, in order to measure the dispersion stability of the CeZnO metal oxide particles and CeO ₂ metal oxide particles in the electrolyte, the CeZnO metal oxide was mixed and stirred to 1 wt% in a mixed solution with a Nafion solution, and then left to stand for 24 hours. Precipitation was confirmed, and the results are shown in Tables 8 and 7 (a) to (d).

division Particle size measurement result (D50) Whether sediment is generated Before mixing with Nafion After mixing with Nafion Preparation Example 2-1 57 nm 48 nm X Preparation Example 2-2 90 nm 57 nm X Preparation Example 2-3 158 nm 121 nm X Preparation Example 2-4 88 nm 77 nm X Preparation Example 2-5 100 nm 89 nm X Preparation Example 2-6 141 nm 133 nm X Preparation Example 2-7 73 nm 34 nm X Preparation Example 2-8 122 nm 113 nm X CeO ₂ metal oxide particles 90.6 nm 6,070nm O

5A and 6B, it can be seen that both the CeZnO metal oxide and the CeO ₂ metal oxide of Preparation Example 2-2 are well dispersed in the Nafion solution, but when comparing FIGS. 5B and 6B, the case of FIG. 5B While the acidity is well maintained, it can be seen that the CeO ₂ metal oxide of FIG. 6B has a great dispersibility and begins to generate sediment.

Experimental Example 4 : Fenton  Test( Fenton  test), ion conductivity measurement

Prepared in Preparation Example 2-1 CeZnO metal oxide powder was added to DI-water to be 1 wt% of the total weight, and then ultrasonic treatment was performed for 24 hours to prepare a CeZnO metal oxide dispersion solution.

Next, the NaZion solution was sonicated with a CeZnO metal oxide dispersion solution sonicated in 1% by weight of the total weight of the mixed solution, and stirred for 5 hours to prepare a coating solution.

Next, the coating solution was coated on a glass substrate using a film applicator to form a coating film, dried at 80° C. for 1 hour, and then heat treated at 150° C. for 1 hour to prepare a single film having a thickness of 20 μm. Did.

In the same manner, a single membrane having a thickness of 20 μm was prepared using CeZnO metal oxide particles of Preparation Examples 2-2 to 2-8 and Comparative Preparation Examples 2-1 to 2-5 instead of Preparation Example 2-1.

(1) Each of the single membranes containing the CeZnO metal oxide powder was decomposed by immersing radicals in an artificially generated aqueous solution by adding hydrogen peroxide to an aqueous ferrous sulfate solution, and then measuring the fluorine ion concentration to evaluate the durability of the electrolyte membrane. , The results are shown in Table 4 below.

(2) The ion conductivity of the single layer containing the CeZnO metal oxide powder was measured by impedance using a 4-pole method, and hydrogen ion conductivity was measured, and the results are shown in Table 9 below.

division Durability evaluation
(μmol/hrㆍg) Ion conductivity
(S/cm) Preparation Example 2-1 25.2 0.126 Preparation Example 2-2 31.7 0.122 Preparation Example 2-3 33.3 0.123 Preparation Example 2-4 18.9 0.127 Preparation Example 2-5 14.1 0.127 Preparation Example 2-6 7.3 0.121 Preparation Example 2-7 35.5 0.127 Preparation Example 2-8 6.9 0.122 Comparative Preparation Example 2-1 54.4 0.124 Comparative Preparation Example 2-2 52.8 0.113 Comparative Preparation Example 2-3 54.3 0.123 Comparative Preparation Example 2-4 53.7 0.125 Comparative Preparation Example 2-5 47.1 0.117

Looking at the experimental results in Table 9, Preparation Examples 2-1 to 2-8 showed a concentration of fluorine ions of 40 μmol/hr·g or less, and it was confirmed that they had excellent durability, and excellent ions of 0.120 S/cm or more. It was confirmed that it had conductivity. On the other hand, in Comparative Preparation Examples 2-1 to 2-5, the fluoride ion concentration was 45 μmol/hr·g or more, showing a tendency of poor overall durability. Comparative Preparation Example 2-2 and Comparative Preparation Example 2-5 In the case of, compared with the preparation example, ionic conductivity was significantly lower. And, looking at the results of the durability evaluation measurements of Preparation Examples 2-1 to 2-8, the fluoride ion concentration tends to decrease as the Ce content increases, which increases the radical removal effect by Ce, thereby attacking the electrolyte membrane. As the radicals to be decreased, it was confirmed that the concentration of eluted fluorine ions decreased and durability was increased.

Example 1: Preparation of electrolyte membrane

A Nafion solution was prepared by mixing 1 part by weight of spherical hollow silica having an average particle diameter of 50 nm with respect to 100 parts by weight of Nafion, a fluorine-based ionomer.

Next, the porous support prepared in Preparation Example 1-1 was impregnated with the Nafion solution, then taken out, put into a vacuum oven, and dried at 80° C. for 10 minutes. Next, a heat treatment was performed at 160° C. for 3 minutes to prepare a porous support impregnated with an electrolyte having a thickness of 15 μm.

Example 2 to 3 and Comparative example  1 to 2

Prepared under the same conditions as in Example 1, a porous support impregnated with an electrolyte was prepared by changing the type of the support as shown in Table 10 below.

Experimental Example  5: weight variation coefficient measurement

(1) The weight variation coefficient (CV1,%) was calculated through the following equation 2 by measuring the weight of the PTFE porous support before the electrolyte impregnation prepared in Examples and Comparative Examples and the weight of the electrolyte membrane coated with the electrolyte layer on the support after impregnation of the electrolyte. It was calculated.

[Relationship 1]

Weight coefficient of variation (CV1,%) = (thickness of porous support after electrolyte treatment-weight of porous support before electrolyte treatment) / (weight of porous support before electrolyte treatment) × 100%

division Type of support Before electrolyte impregnation
Weight (g) Weight after electrolyte impregnation (g) Weight fluctuation coefficient
(%) Example 1 Preparation Example 1-1 7 17.1 145% Example 2 Preparation Example 1-3 8.5 14.0 65% Example 3 Preparation Example 1-12 5 19.5 290% Comparative Example 1 Comparative Preparation Example 1-1 9.2 11.3 23% Comparative Example 2 Comparative Preparation Example 1-3 7.6 10.2 35% Comparative Example 3 Comparative Preparation Example 1-5 8.6 9.1 6% Comparative Example 4 Comparative Preparation Example 1-6 4.7 34.5 633% Comparative Example 5 Comparative Preparation Example 1-8 9.4 10.6 13% Comparative Example 6 Comparative Preparation Example 1-9 4.3 28.8 569% Comparative Example 7 Comparative Preparation Example 1-10 9.5 10.7 12%

Looking at the experimental results in Table 10, in Examples 1 to 3, it was confirmed that the appropriate weight increases in the weight variation coefficient of 40% or more, preferably 60% to 300%. On the other hand, when using the porous support of Comparative Preparation Example 1-1, Comparative Preparation Example 1-3, Comparative Preparation Example 1-5 and Comparative Preparation Example 1-8, wherein the average pore size of the porous support was less than 0.08 µm, excellent tensile strength Although having strength and modulus, the amount of the coefficient of variation of the weight was less than 40% due to the small amount of electrolyte impregnation in the porous support.

In addition, when the porous supports of Comparative Preparation Examples 1-6 and Comparative Preparation Examples 1-9 were used, the weight fluctuation coefficient was 300% or more, which showed very high results.

Referring to Table 10, it can be seen that Examples 1 to 3 exhibit high weight variation coefficient characteristics compared to Comparative Examples 1 to 2. Therefore, it can be seen that Comparative Examples 1 to 3 according to an embodiment of the present invention retain more electrolyte.

Manufacturing example  One : PEMFC Preparation of composite electrolyte membrane

The PTFE porous support prepared in Preparation Example 1-1 was prepared.

A first ionomer solution was prepared by mixing CeZnO metal oxide particles (radical scavenger) of the average particle size (D ₅₀ ) 122 nm and the remaining amount of Nafion solution prepared in Preparation Example 2-8, but CeZnO metal oxide particles 0.12% by weight and First ionomer solutions 1 to 2, each containing 0.3% by weight, were prepared.

In addition, CeZnO metal oxide particles of the Preparation Example 2-8 (radical scavenger) And a second ionomer solution was prepared by mixing the remaining amount of Nafion solution to prepare second ionomer solutions 1 to 2, each containing 0.08% and 0.6% by weight of CeZnO metal oxide particles, respectively.

The PTFE porous support was fixed to a glass substrate, and the first ionomer solution 1 was impregnated on one surface of the PTFE porous support using an applicator. Next, one surface of the PTFE porous support that was continuously impregnated into the first ionomer solution 1 was impregnated into the first ionomer solution 2. Next, the PTFE porous support impregnated in the first ionomer solution 1 to 2 was introduced into a vacuum oven at 80° C. and dried for 10 minutes to form a first ionomer layer on one surface of the PTFE porous support. At this time, the first ionomer layer was formed in a multi-layer in the order of L1 and L2 by applying ionomers having different radical scavenger contents (% by weight). L1 is the first ionomer layer formed by the first ionomer solution 1, and L2 is the first ionomer layer formed by the first ionomer solution 2.

Next, using the applicator, the other surface of the PTFE porous support having the multi-layered first ionomer layer was impregnated into the second ionomer solution 1. Next, the PTFE porous support, which was impregnated continuously in the second ionomer solution 1, was impregnated in the second ionomer solution 2. Next, the PTFE porous support impregnated with the second ionomer solution 1 to 2 was introduced into a vacuum oven at 80° C. and dried for 10 minutes to form a second ionomer layer on one surface of the PTFE porous support. At this time, the second ionomer layer was formed in multiple layers in the order of L3 and L4 by applying ionomers having different radical scavenger content (% by weight). L3 is the second ionomer layer formed by the second ionomer solution 1, and L4 is the second ionomer layer formed by the second ionomer solution 2.

At this time, the average content of CeZnO metal oxide applied to the entire first ionomer layer containing L1 and L2 is about 1.05% by weight, and the average content of CeZnO metal oxide applied to the entire second ionomer layer containing L3 and L4. Is about 1.7% by weight.

Next, at 160° C., heat treatment was performed for 3 minutes to prepare a composite electrolyte membrane for PEMFC having a first ionomer layer thickness of 8 μm, a second ionomer layer thickness of 8 μm, and a PTFE porous support layer of 14 μm.

[Equation 2]

D _60~100 > D _0~40

In Equation 2, D _0-40 and D _60-100 are the content of the radical scavenger in the total weight of the radical scavenger in the ionomer layer at a distance away from the bonding surface between the first ionomer layer and the support in the thickness direction of the support. As a meaning (% by weight), when the end distance of the first ionomer layer farthest from the bonding surface between the first ionomer layer and the support is 100%, D _0-40 is the first ionomer from the bonding surface. The content (% by weight) of radical scavengers in the first ionomer layer located at a distance of 0% to 40% in the direction of the end of the layer, D _{60 to 100} is 60% in the direction of the end of the first ionomer layer from the bonding surface It means the content (% by weight) of radical scavenger in the first ionomer layer located at a distance of ~ 100%.

[Equation 3]

D' _{60 ~100} >D' _{0 ~ 40}

In Equation 3, D' _{0 ~ 40} and D' _{60 ~ 100} are radical scavengers in the ionomer layer at a distance away from the bonding surface between the second ionomer layer and the support in the thickness direction of the support radical scavenger in the total weight As the content (% by weight), when the end distance of the second ionomer layer farthest from the bonding surface between the first ionomer layer and the support is based on 100%, D' _{0 to 40} is from the bonding surface. The content (%) of the radical scavenger in the second ionomer layer located at a distance of 0% to 40% in the direction of the end of the second ionomer layer, and D' _{60 to 100} from the junction surface toward the end of the second ionomer layer It means the content (%) of radical scavengers in the second ionomer layer located at a distance of 60% to 100%.

Manufacturing example 2 to 6 and Comparative manufacturing example 1 to 8

A composite electrolyte membrane was prepared in the same manner as in Preparation Example 1, except for Table 10 and the radical scavenger content and type in the Nafion solution for forming the first ionomer layer and/or the second ionomer layer. And Comparative Preparation Examples 1 to 8 to prepare PEMFC composite electrolyte membranes, respectively.

In Table 11, D _{0 ~ 40} , D _{60 ~ 100} , D' _{0 ~ 40} and Each of D' _{60 to 100} is as defined in Equation 1 or Equation 3 above.

Manufacturing example  7 ~ Manufacturing example  8

In the same manner as in Preparation Example 1, the first ionomer solutions 1 to 2 and the second ionomer solutions 1 to 2 of the same concentration were prepared, respectively, and PEMFC composite electrolyte membranes were prepared using the same. In this case, the first and second ionomer solutions were prepared by using CeO ₂ (purchased by US Research Nanomaterials, Inc.) instead of CeZnO metal oxide of Preparation Example 2-8 as a radical scavenger.

And, the radical scavenger content is shown in Table 11 below.

division In the first ionomer layer
Radical scavenger content In the second ionomer layer
Radical scavenger content Average content D _0~40 D _60~100 Average content D' _{0 ~ 40} D' _{60 ~100} Preparation Example 1 1.05% by weight 0.6% by weight 1.5% by weight 1.7% by weight 0.4% by weight 3.0% by weight Preparation Example 2 1.05% by weight 0.6% by weight 1.5% by weight 1.9% by weight 0.8% by weight 3.0% by weight Preparation Example 3 0.8% by weight 0.6% by weight 1.0% by weight 1% by weight 0.4% by weight 1.6% by weight Preparation Example 4 0.65% by weight 0.3% by weight 1.0% by weight 1% by weight 0.4% by weight 1.6% by weight Preparation Example 5 0.55% by weight 0.3% by weight 0.8% by weight 1% by weight 0.4% by weight 1.6% by weight Preparation Example 6 0.35% by weight 0.1% by weight 0.6% by weight 0.6% by weight 0.4% by weight 0.8% by weight Preparation Example 7 1.05% by weight 0.6% by weight 1.5% by weight 1.7% by weight 0.4% by weight 3.0% by weight Preparation Example 8 1.05% by weight 0.6% by weight 1.5% by weight 1.9% by weight 0.8% by weight 3.0% by weight Comparative Production Example 1 1% by weight 0.4% by weight 1.6% by weight 1% by weight 0.4% by weight 1.6% by weight Comparative Production Example 2 1.9% by weight 0.8% by weight 3.0% by weight 1.05% by weight 0.6% by weight 1.5% by weight Comparative Production Example 3 1.3% by weight 0.3% by weight 1.0% by weight 1% by weight 1.6% by weight 0.4% by weight Comparative Production Example 4 0.65% by weight 1.0% by weight 0.3% by weight 1% by weight 0.4% by weight 1.6% by weight Comparative Production Example 5 0.65% by weight 0.3% by weight 1.0% by weight 0.25% by weight 0% by weight 0.5% by weight Comparative Production Example 6 0.65% by weight 0.3% by weight 1.0% by weight 2.5% by weight 1.0% by weight 4.0% by weight Comparative Production Example 7 0.15% by weight 0% by weight 0.3% by weight 1% by weight 0.4% by weight 1.6% by weight Comparative Production Example 8 2% by weight 1.0% by weight 3.0% by weight 1% by weight 0.4% by weight 1.6% by weight

Experimental Example  6: PEMFC Durability and ion conductivity measurement experiment of composite electrolyte membrane

One) Fenton  Test( Fenton test)

Table 11 Experimental Examples 1 to 6 and Comparative Examples 1 to 10 were performed to test the composite electrolyte membrane for PEMFC by varying the radical scavenger content and type in the Nafion solution for forming the first ionomer layer and/or the second ionomer layer, respectively. Prepared to a size of 5 cm ⅹ 5 cm (horizontal length), and dried in an oven at 80° C. for 5 hours or more, and then measured mass. Was immersed in a solution prepared by 200g 3ppm Fe ^{+ 2} was added to the prepared specimen in a 2% hydrogen peroxide solution and allow to stand for 80 ℃, 120 hours. The fluorine ion concentration eluted from the test piece was measured using a fluorine ion selection electrode, and the results are shown in Table 12. In the Fenton test, the lower the measured value, the lower the elution of fluorine ions, that is, the durability of the electrolyte membrane is excellent.

2) Measurement of ion conductivity

Table 11 Experimental Examples 1 to 6 and Comparative Examples 1 to 10 were carried out to test the composite electrolyte membrane for PEMFC by varying the radical scavenger content and type in the Nafion solution for forming the first ionomer layer and/or the second ionomer layer, respectively. Was prepared in a size of 1 cm ⅹ 5 cm (horizontal length), immersed in distilled water, immersed in an oven at 80° C. for 5 hours, and then immersed in distilled water to measure the impedance after setting the temperature at 25° C. and calculating the ion conductivity. Table 12 shows the results.

division Durability evaluation (μmol/hrㆍg) Ion conductivity (S/cm) Preparation Example 1 2.1 0.117 Preparation Example 2 1.9 0.102 Preparation Example 3 9.8 0.121 Preparation Example 4 9.7 0.124 Preparation Example 5 11.8 0.126 Preparation Example 6 18.7 0.131 Preparation Example 7 2.3 0.114 Preparation Example 8 2.1 0.100 Comparative Production Example 1 9.5 0.112 Comparative Production Example 2 10.5 0.101 Comparative Production Example 3 28.3 0.123 Comparative Production Example 4 15.8 0.124 Comparative Production Example 5 54.8 0.130 Comparative Production Example 6 1.8 0.094 Comparative Production Example 7 14.1 0.129 Comparative Production Example 8 9.8 0.098

Looking at the experimental results of Table 12, in the case of Preparation Examples 1 to 8, the ion scavenger content in the first ionomer and the second ionomer is higher than that of Comparative Production Example 1 in which the radical scavenger content is the same, and has high ion conductivity. It can be confirmed that it has excellent performance. In particular, Preparation Examples 1 to 6 using CeZnO-based metal oxide particles as a PEMFC radical scavenger have relatively lower fluorine ion concentrations than Preparation Examples 7 to 8 using CeO ₂ as a PEMFC radical scavenger for better durability and ions. The results showed conductivity.

On the other hand, in the case of Comparative Production Example 2 in which the average concentration of the radical scavenger of the first ionomer layer is higher than that of the second ionomer layer, the ion conductivity is significantly lower than that of Production Example 1.

And, in the first ionomer layer D _{0 ~ 40} D _{60 ~ 100 has a} more radical scavenger content Comparative Preparation Example 3 and The second case of the ionomer in layer D _{0 ~ 40 60 ~ 100} D is more radical scavenger Comparative Production Example 4 The content of large, as compared to Production Example 4, there is a problem in poor durability larger relatively.

In addition, in Comparative Production Example 5 in which the average content of the radical scavenger in the first ionomer layer was too low and in Comparative Production Example 7 in which the average content of the radical scavenger in the second ionomer layer was too low, the ion conductivity was good, but the durability was very high. It gave bad results.

In addition, in Comparative Production Example 6 in which the average content of radical scavengers in the first ionomer layer was excessive and in Comparative Production Example 8 in which the average content of radical scavengers in the second ionomer layer was too high, durability was very good, but ion conductivity was high. It was confirmed that there was a problem that the performance of the electrolyte membrane was greatly reduced because it was too low.

Through the above Examples and Experimental Examples, it was confirmed that the composite electrolyte membrane for PEMFC prepared by the method proposed by the present invention not only has an excellent radical removal effect, but also has excellent physical properties, through which durability, that is, long-term life stability and performance. It is expected that the improved membrane-electrode assembly for PEMFC and PEMFC can be provided.

As described above, the present invention has been described in detail with reference to preferred examples and experimental examples, but the present invention is not limited by the examples and experimental examples, and has ordinary knowledge in the art within the technical spirit and scope of the present invention. Various modifications and changes are possible by the ruler.

DESCRIPTION OF SYMBOLS 1 Porous support body 2 1st ionomer layer 3rd 2nd ionomer layer
5.: radical scavenger 10: composite electrolyte membrane 21: gas diffusion layer
22: catalyst layer 23: anode electrode substrate 23': cathode electrode substrate

Claims (16)

A first ionomer layer disposed in the anode direction; It includes; a support layer and a second ionomer layer disposed in the cathode (cathode) direction,
The first ionomer layer and the second ionomer layer include a radical scavenger to satisfy Equation 1 below,
The radical scavenger distribution in the first ionomer layer satisfies the following equation 2, PEMFC composite electrolyte membrane;
[Equation 1]
Average content of radical scavenger in the first ionomer layer <Average content of radical scavenger in the second ionomer layer
[Equation 2]
D _60~100 > D _0~40
In Equation 2, D _0-40 and D _60-100 are the content of the radical scavenger in the total weight of the radical scavenger in the ionomer layer at a distance away from the bonding surface between the first ionomer layer and the support in the thickness direction of the support. (% by weight), when the end distance of the first ionomer layer farthest from the bonding surface between the first ionomer layer and the support is based on 100%, D _0-40 is the first ionomer from the bonding surface. The content (% by weight) of radical scavenger in the first ionomer layer located at a distance of 10% to 40% in the direction of the end of the layer, D _{60 to 100} is 60% in the direction of the end of the first ionomer layer from the bonding surface It means the content (% by weight) of radical scavenger in the first ionomer layer located at a distance of ~ 90%.
According to claim 1, The average content of the radical scavenger in the first ionomer layer and the average content of the radical scavenger in the second ionomer layer is 1: 1.25 ~ 10 composite electrolyte membrane for PEMFC, characterized in that the weight ratio;
delete According to claim 1, The radical scavenger content of the D _{60 ~ 100} in the first ionomer layer is 0.6 ~ 2.4% by weight, the radical scavenger content of D _{0 ~ 40} is characterized in that 0.01 ~ 0.6% by weight PEMFC composite electrolyte membrane.
The method according to claim 1, wherein the distribution of radical scavengers in the second ionomer layer satisfies the following equation 3;
[Equation 3]
D' _{60 ~100} >D' _{0 ~ 40}
In Equation 3, D' _{0 ~ 40} and D' _{60 ~ 100} are radical scavengers in the ionomer layer at a distance away from the bonding surface between the second ionomer layer and the support in the thickness direction of the support, radical scavenger in the total weight As the content (% by weight), when the end distance of the second ionomer layer farthest from the bonding surface between the first ionomer layer and the support is based on 100%, D' _{0 to 40} is from the bonding surface. The content (%) of the radical scavenger in the second ionomer layer located at a distance of 10% to 40% in the direction of the end of the second ionomer layer, and D' _{60 to 100} from the bonding surface toward the end of the second ionomer layer It means the content (%) of radical scavengers in the second ionomer layer located at a distance of 60% to 90%.
According to claim 5, The radical scavenger content of the D' _{60 ~ 100} in the first ionomer layer is 0.8 ~ 3% by weight, the radical scavenger content of D' _{0 ~ 40} is 0.1 ~ 0.8% by weight Characterized as a composite electrolyte membrane for PEMFC.
The method of claim 1, wherein the support layer comprises a PTFE (Poly tetra fluoro ethylene) porous support,
The PTFE porous support is a composite electrolyte membrane for PEMFC, characterized in that the tensile strength in the uniaxial direction (longitudinal direction) is 40 MPa or more and the tensile strength in the biaxial direction (width direction) is 40 MPa or more when measured according to ASTM D 882. .
8. The composite electrolyte membrane for PEMFC according to claim 7, wherein the PTFE porous support has a uniaxial (longitudinal) modulus of 40 MPa or more and a biaxial (wide) modulus of 40 MPa or more.
According to claim 7, When measured in accordance with the PTFE porous support ASTM D 882, the uniaxial direction modulus and the biaxial direction modulus values PEMFC composite electrolyte membrane characterized in that it satisfies the following equation 4;
[Equation 4]
0 ≤ │(1 axis direction modulus-2 axis direction modulus)/(1 axis direction modulus)ⅹ100%│ ≤ 54%
8. The composite electrolyte membrane for PEMFC according to claim 7, wherein the PTFE porous support has an average pore size of 0.080 to 0.200 µm, and an average porosity of 60 to 90%.
Step 1 of preparing a PTFE porous support;
A second step of forming a first ionomer layer on one surface of the PTFE porous support;
A third step of forming a second ionomer layer on the other surface of the support on which the first ionomer layer is formed; And
Including; a fourth step of heat-treating the PTFE porous support having a first ionomer layer and a second ionomer layer;
The first ionomer layer and the second ionomer layer of the prepared composite electrolyte membrane include a radical scavenger to satisfy Equation 1 below,
The radical scavenger distribution in the first ionomer layer is a method of manufacturing a composite electrolyte membrane for PEMFC, characterized in that it satisfies Equation 2 below;
[Equation 1]
Average content of radical scavenger in the first ionomer layer <Average content of radical scavenger in the second ionomer layer
[Equation 2]
D _60~100 > D _0~40
In Equation 2, D _0-40 and D _60-100 are the content of the radical scavenger in the total weight of the radical scavenger in the ionomer layer at a distance away from the bonding surface between the first ionomer layer and the support in the thickness direction of the support. (% by weight), when the end distance of the first ionomer layer farthest from the bonding surface between the first ionomer layer and the support is based on 100%, D _0-40 is the first ionomer from the bonding surface. The content (% by weight) of radical scavenger in the first ionomer layer located at a distance of 10% to 40% in the direction of the end of the layer, D _{60 to 100} is 60% in the direction of the end of the first ionomer layer from the bonding surface It means the content (% by weight) of radical scavenger in the first ionomer layer located at a distance of ~ 90%.
The method of claim 11, wherein the first step of the porous PTFE support is a step 1-1 to prepare a paste (paste) by mixing and stirring the PTFE powder and liquid lubricant;
1-2 steps of aging the paste;
Steps 1-3 for producing an unbaked tape by extruding and rolling the aged paste;
After drying the green tape, steps 1-4 to remove the liquid lubricant;
Step 1-5 of uniaxially stretching the unbaked tape from which the lubricant has been removed;
Steps 1-6 of biaxially stretching the uniaxially stretched micro tape; And
Method of manufacturing a composite electrolyte membrane for PEMFC, characterized in that it comprises; 1-7 steps of firing.
13. The composite electrolyte for PEMFC according to claim 12, wherein the uniaxial stretching of steps 1-5 is performed in the longitudinal direction under an stretching temperature of 260°C to 350°C and an stretching speed of 6 to 12 M/min. Method of manufacturing a membrane.
The composite electrolyte for PEMFC according to claim 12, wherein the biaxial stretching in steps 1-6 is performed in the width direction under a stretching temperature of 150°C to 260°C and a stretching speed of 10 to 20 M/min. Method of manufacturing a membrane.
Anode (oxide electrode); Anode catalyst layer; Claim 1, 2 and any one of the composite electrolyte membrane of any one selected from claims 4 to 10; Cathode catalyst layer; And cathode (reduction electrode); PEMFC membrane-electrode assembly comprising a.
An electricity generating unit including the membrane-electrode assembly and separator of claim 15 and generating electricity through an electrochemical reaction between a fuel and an oxidizing agent;
A fuel supply unit supplying fuel to the electricity generation unit; And
A polymer electrolyte membrane fuel cell comprising; an oxidizing agent supply unit for supplying an oxidizing agent to the generator.

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