KR101860856B1 - Porous support with high elongation for fuel cell-electrolyte membrane, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a porous support for fuel cell electrolyte membranes, a fuel cell electrolyte membrane comprising the same, a membrane-electrode assembly comprising the same, and a fuel cell. By providing the porous support for fuel cell electrolyte membranes having improved mechanical properties even when a stretching ratio is increased as compared to existing porous supports used in existing electrolyte membranes, it is possible to provide fuel cells and fuel cell materials with improved performance.

Description

Technical Field [0001] The present invention relates to a high-stretch porous support for a fuel cell electrolyte membrane and a manufacturing method thereof,

The present invention relates to a support for a fuel cell electrolyte membrane, and more particularly, to a porous support used for an electrolyte membrane for a fuel cell, an electrolyte membrane for a fuel cell comprising the same, a membrane-electrode assembly using the same, And a manufacturing method thereof.

A fuel cell is a power generation system that converts chemical energy generated by electrochemically reacting fuel (hydrogen or methanol) and oxidizer (oxygen) directly into electrical energy. It is a next generation energy source with high energy efficiency and eco- Research and development. Fuel cells can be selectively used for high temperature and low temperature fuel cells according to application fields and are usually classified according to the kind of electrolyte. Solid oxide fuel cell (SOFC), molten carbonate An alkali fuel cell (AFC), a polymer electrolyte fuel cell (PEMFC), and the like are being developed for low temperature applications.

The two types of polymer electrolyte fuel cells are divided into proton exchange membrane fuel cell (PEMFC), which uses hydrogen gas as fuel, and direct methanol (PEMFC) And a direct methanol fuel cell (DMFC). Polymer electrolyte fuel cells are attracting attention as portable, automotive, and household power sources because of their low operating temperature of less than 100, the elimination of leakage problems caused by the use of solid electrolytes, quick start and response characteristics, and excellent durability. Particularly, as a high-output fuel cell having a higher current density than other types of fuel cells, miniaturization is possible, and thus research into a portable fuel cell continues.

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

In the oxidizing electrode, hydrogen or methanol, which is a fuel, is supplied to generate hydrogen ions and electrons. Hydrogen ions and electrons are generated in the oxidizing electrode, and hydrogen ions and oxygen that pass through the polymer electrolyte membrane are combined with each other in the reducing electrode. .

In this membrane-electrode assembly, the electrode catalyst layer of the oxidized electrode and the reducing electrode is coated on both surfaces of the ion conductive electrolyte membrane, and the material forming the electrode catalyst layer is Pt (platinum) or Pt-Ru (platinum-ruthenium) Is supported on a carbon carrier. The membrane-electrode assembly (MEA), which is considered to be a core component of the electrochemical reaction of the fuel cell, uses an ion conductive electrolyte membrane and a platinum catalyst, Is considered to be the most important part to improve the performance and price competitiveness.

Conventional methods for preparing commonly used MEAs include preparing a paste by mixing a catalyst material with a hydrogen ion conductive binder, i.e., a fluorine-based Nafion Ionomer, and water and / or an alcohol solvent, This is coated on a carbon cloth or a carbon paper, which serves as a gas diffusion layer, as well as an electrode support for supporting the catalyst layer, and then dried and thermally fused to the hydrogen ion conductive electrolyte membrane.

Oxidation and reduction reaction of hydrogen and oxygen by the catalyst in the catalyst layer; The transfer of electrons by the adherent carbon particles; Securing a passage for supplying hydrogen, oxygen and moisture and discharging a surplus gas after the reaction; And the movement of oxidized hydrogen ions must be simultaneously performed. Further, 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 and the catalyst and the ion conductive polymer electrolyte membrane meet, and the interface between the catalyst layer and the electrolyte membrane, And the gas diffusion layer should be uniformly bonded to reduce ohmic polarization at the interface. Therefore, in order to improve the performance of the fuel cell by minimizing the interface resistance between the catalyst layer and the electrolyte membrane, it is necessary not only to have a bonding force between the catalyst layer and the electrolyte membrane during the production of the MEA, It should be maintained.

Recently, a technique 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 has actively been developed, but the interface uniformity is still limited.

Further, in the case of an MEA having the above-described structure, since an electrolyte membrane having a large thickness is usually used, the transfer of hydrogen ions may be delayed to deteriorate performance.

Further, as the movement of the hydrogen ions and the use time are prolonged in driving the fuel cell, the interface between the catalyst layer and the electrolyte membrane and the interface bonding between the catalyst layer and the gas diffusion layer are weakened and separated from each other. Therefore, when the fuel cell is applied to the fuel cell, the performance of the fuel cell may deteriorate.

In order to shorten the movement time of the hydrogen ion, etc., there is a method of reducing the thickness of the electrolyte membrane and thinning the thickness of the porous support constituting the electrolyte membrane. In order to reduce the thickness of the support, Is not only greatly reduced but also has a problem of poor economical efficiency and commerciality because of a high defect rate in the production of a support.

Korean Patent Publication No. KR 2010-0077483 A (2010.07.08)

SUMMARY OF THE INVENTION The present invention has been devised to solve the problems described above, and an object of the present invention is to provide a support for a fuel cell electrolyte membrane, which is manufactured at a specific stretching ratio and a specific stretching speed during manufacture of a support constituting an electrolyte membrane.

Also, it is intended to provide a fuel cell electrolyte membrane, a membrane-electrode assembly, and a fuel cell including the fuel cell electrolyte membrane, to which the support for the fuel cell electrolyte membrane is applied.

The porous support for a fuel cell electrolyte membrane of the present invention for solving the above problems has a modulus in a uniaxial direction (longitudinal direction) of not less than 40 MPa and a modulus in a biaxial direction (width direction) Can be more than 40 MPa.

In one preferred embodiment of the present invention, the porous support of the present invention has a tensile strength in a uniaxial direction (longitudinal direction) of 40 MPa or more and a tensile strength in a biaxial direction (width direction) of 40 MPa or more.

In one preferred embodiment of the present invention, the porous support of the present invention can satisfy the following Equation 1 when measured according to ASTM D 882, in which the uniaxial direction modulus and the biaxial direction modulus value are satisfied.

[Equation 1]

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

In one preferred embodiment of the present invention, the porous support of the present invention may have a stretching ratio in a uniaxial direction (longitudinal direction) of 3 to 10 times and a stretching ratio in a biaxial direction (width direction) of 15 to 50 times.

In one preferred embodiment of the present invention, the porous support of the present invention may have a uniaxial (longitudinal) stretching ratio of 6 to 9.5 times and a biaxial (widthwise) stretching ratio of 25 to 45 times.

In one preferred embodiment of the present invention, the porous support of the present invention may have a uniaxial (longitudinal) stretching ratio of 6.2 to 9 times and a biaxial (widthwise) stretching ratio of 28 to 45 times.

In one preferred embodiment of the present invention, the porous support of the present invention has a stretching ratio (or aspect ratio) of 1: 3.00 to 8.5, preferably 1: 3.50 To 7.0.

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

In one preferred embodiment of the present invention, the porous support of the present invention may be a PTFE porous support containing polytetrafluoroethylene (PTFE).

In one preferred embodiment of the present invention, the porous support may have an average thickness of 5 to 25 탆.

Another object of the present invention is to provide a method for producing porous supports of various forms as described above, comprising the steps of: mixing and stirring a PTFE powder and a liquid lubricant to prepare a paste; 2) aging the paste; A third step of extruding and rolling the aged paste to produce an unflavicious tape; Drying the uncured tape, and then removing the liquid lubricant; 5) uniaxially stretching the untreated tape from which the lubricant has been removed; Biaxially stretching the uniaxially stretched untreated tape; And firing step (7).

In one preferred embodiment of the present invention, the first-stage paste may contain 15 to 35 parts by weight of a lubricant based on 100 parts by weight of the PTFE powder.

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

In one preferred embodiment of the present invention, the two stages of aging can be performed by allowing the aging to proceed at a temperature of 30 ° C to 70 ° C for 12 to 24 hours.

In one preferred embodiment of the present invention, the three-step extrusion can be performed by compressing the aged paste in a compressor to produce a PTFE block, and then extruding the PTFE block under a pressure of 0.069 to 0.200 Ton / cm ² .

As a preferred embodiment of the present invention, the rolling in the three stages can be carried out by calendering at an oil pressure of 5 to 10 MPa and at a temperature of 50 to 100.

As a preferred embodiment of the present invention, the drying process of four stages is a process for removing the lubricant, and drying can be performed at 100 ° C to 200 ° C while moving the untreated tape at a speed of 1 to 5 M / min.

As a preferred embodiment of the present invention, in the uniaxial stretching in the five-step process, the untreated tape from which the lubricant has been removed is stretched in the longitudinal direction to 3 to 10 times, preferably 6 to 9.5 times, more preferably 6.2 to 9 times Can be performed.

In one preferred embodiment of the present invention, the five-step uniaxial stretching can be carried out 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 6 stages is conducted by stretching uniaxially stretched untreated tapes 15 to 50 times, preferably 25 to 45 times, more preferably 28 to 45 times in the width direction Can be performed.

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

In one preferred embodiment of the present invention, the firing in the seventh step may be performed at a temperature of 350 ° C to 450 ° C.

As a preferred embodiment of the present invention, there is provided a method for preparing a fluorine-containing ionomer, comprising the steps of: 8) impregnating a fluorine-based ionomer solution with a porous support prepared by performing a 7-step process; And drying and heat-treating the impregnated PTFE porous support.

As a preferred embodiment of the present invention, the fluorine-based ionomer solution of the eight-step may further include at least one moisture absorbent selected from the group consisting of zeolite, titania, zirconia, and montmorillonite.

In one preferred embodiment of the present invention, the fluorine-based ionomer solution of 8 stages may further contain 0.05 to 5% by weight of hollow silica in the total weight of the solution.

In one preferred embodiment of the present invention, the fluorine-based ionomer may include at least one selected from Nafion, Flemion, and Aciplex.

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

In one preferred embodiment of the present invention, the volume of the closed pores of the heat-treated porous support in the step 9 may be 90 vol% or more with respect to the total pore volume.

Another object of the present invention is to provide a fuel cell electrolyte membrane comprising various types of porous supports as described above, wherein the porous support; And a first electrolyte film formed on one side of the support and a second electrolyte film formed on the other side of the support.

As a preferred embodiment of the present invention, the fuel cell electrolyte membrane may have a weight coefficient of variation (CV1) of the following relational expression 1 of not less than 40%.

[Relation 1]

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

As a preferred embodiment of the present invention, the fuel cell electrolytic 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 in a uniaxial direction (longitudinal direction) of 50 MPa or more and a tensile strength in a biaxial direction (width direction) It may be more than 48 MPa.

Still another object of the present invention relates to a membrane-electrode assembly (MEA), which comprises a support for the fuel cell electrolyte membrane.

As a preferred embodiment of the present invention, the membrane-electrode assembly (MEA) of the present invention comprises the fuel cell electrolyte membrane; Anode (anode); And a cathode (cathode), wherein the oxidant electrode and the reducing electrode comprise a catalyst layer; A gas diffusion layer; And an electrode substrate.

It is still another object of the present invention to provide a fuel cell comprising: an electricity generating unit generating electricity through an electrochemical reaction between a fuel and an oxidant; A fuel supply unit for supplying fuel to the electricity generation unit; And an oxidizing agent supply unit for supplying an oxidizing agent to the generating unit, wherein the electricity generating unit includes the membrane-electrode assembly and the separator.

In a preferred embodiment of the present invention, the fuel cell includes a membrane-electrode assembly and a separator, and includes a first step of forming an electricity generating part generating electricity through an electrochemical reaction between a fuel and an oxidant; A second step of forming a stack between the membrane electrode assemblies via a separator; Forming a fuel supply unit for supplying fuel to the electricity generating unit; And forming an oxidant supply unit for supplying the oxidant to the electricity generating unit.

The porous support for a fuel cell electrolyte membrane of the present invention ensures an optimal stretching ratio and elongation speed, and can be manufactured with a very low defective rate, thereby being excellent in economy and commerciality, and securing excellent mechanical properties. As a result, And it is possible to improve the performance of the fuel cell by reducing the total thickness of the fuel cell electrolyte membrane.

1 is a schematic view of a fuel cell electrolyte membrane according to a preferred embodiment of the present invention.
2 is a schematic view of a membrane-electrode assembly according to a preferred embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to a method for producing a porous support for a fuel cell electrolyte membrane of the present invention.

The porous support for a fuel cell electrolyte membrane of the present invention comprises a first step of mixing a PTFE powder and a lubricant to prepare a paste; 2) aging the paste; A third step of extruding and rolling the aged paste to produce an unflavicious tape; Drying the uncured tape, and then removing the liquid lubricant; 5) uniaxially stretching the untreated tape from which the lubricant has been removed; Biaxially stretching the uniaxially stretched untreated tape; And firing step (7).

In the first step, the paste may contain 15 to 35 parts by weight, preferably 15 to 30 parts by weight, more preferably 15 to 25 parts by weight of a lubricant based on 100 parts by weight of the PTFE powder. If the amount of the lubricant is less than 15 parts by weight based on 100 parts by weight of the PTFE fine powder, the porosity may be lowered when the PTFE porous support is formed by the biaxial stretching process described below. If the amount is more than 35 parts by weight, The strength of the support can be weakened.

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

Next, the aging in two stages is a pre-forming step, the paste can be aged at a temperature of 30 to 70 DEG C for 12 to 24 hours, preferably at a temperature of 35 to 60 DEG C for 16 to 20 hours It can be aged. When the aging temperature is less than 35 ° C or the aging time is less than 12 hours, the lubricant coating on the surface of the PTFE powder becomes non-uniform, which may limit the stretching uniformity of the PTFE sheet to be described below. If the aging temperature exceeds 70 ° C or the aging time exceeds 24 hours, the pore size of the support after the biaxial stretching process may become too small due to the evaporation of the lubricant.

Next, in the third extrusion, the aged paste is compressed in a compressor to produce a PTFE block, and then the PTFE block is pressurized at a pressure of 0.069 to 0.200 Ton / cm ² , preferably at a pressure of 0.090 to 0.175 Ton / cm ² And then extruding it by pressure. At this time, when the pressure-extruding pressure is 0.069 Ton / cm ² The strength of the support may be weakened due to the increase of the pore size of the support, and if it exceeds 0.200 Ton / cm ² , there may be a problem that the pore size of the support after the biaxial stretching process becomes small.

Next, the rolling in the third step can be carried out by calendering at an oil pressure of 5 to 10 MPa and at 50 ° C to 100 ° C. At this time, if the hydraulic pressure is less than 5 MPa, the pore size of the support becomes large and the strength of the support may be weakened, and if it exceeds 10 MPa, the support pore size may be reduced.

Next, the four-step drying can be carried out by a general drying method used in the art. For example, the unfired tape produced by rolling is heated at a temperature of 100 ° C to 200 ° C at a rate of 1 to 5 M / min Conveying at a speed of 2 to 4 M / min, preferably at a temperature of 140 to 190 deg. C, while being conveyed to a conveyor belt. If the drying temperature is less than 100 ° C. or the drying rate is more than 5 M / min, bubbles may be generated during the drawing process due to the evaporation of the lubricant. If the drying temperature is more than 200 ° C., min, the stiffness of the dried tape increases, and slip may occur during the drawing process.

Next, the uniaxial stretching in the five steps is a step of stretching the untreated tape in which the lubricant is removed in the longitudinal direction, and uniaxial stretching is performed using the speed difference between the rollers when the tape is fed through the rollers. In the uniaxial stretching, the untreated tape from which the lubricant has been removed is stretched in the longitudinal direction by 3 to 10 times, preferably by 6 to 9.5 times, more preferably by 6.2 to 9 times, further preferably by 6.3 to 8.2 times It is better to do it. At this time, if the uniaxial stretching ratio is less than 3 times, sufficient mechanical properties can not be secured. If the uniaxial stretching ratio exceeds 10 times, the mechanical properties may be rather reduced and the pores of the support may become too large.

The uniaxial stretching is carried out at a stretching temperature of 260 to 350 占 폚 and a stretching speed of 6 to 12 M / min, preferably a stretching temperature of 270 to 330 占 폚 and a stretching speed of 8 to 11.5 M / min When the uniaxial stretching temperature is lower than 260 占 폚 or the stretching speed is lower than 6 M / min, heat applied to the dry sheet is increased to cause a firing section, and when the uniaxial stretching temperature Exceeds 350 占 폚 or the stretching speed exceeds 12 M / min, slip may occur during the uniaxial stretching process, resulting in a problem that the thickness uniformity is lowered.

Next, in the biaxial stretching in the six steps, stretching is carried out in the width direction (direction perpendicular to uniaxial stretching) of the uniaxially stretched untreated tape, and stretching can be performed in a state in which the end is fixed, have. However, the present invention is not limited thereto, and stretching can be carried out according to a stretching method commonly used in the art. In the present invention, the biaxial stretching can be performed at a stretching rate of 15 to 50 times in the width direction, preferably 25 to 45 times, more preferably 28 to 45 times, still more preferably 29 to 42 times, If the biaxial stretching ratio is 15 times or less, sufficient mechanical properties may not be secured. If the biaxial stretching ratio is more than 50 times, the mechanical properties are not improved and the uniformity of physical properties in the longitudinal direction and / Therefore, it is preferable that the stretching is performed within the above range.

The biaxial stretching is carried out at a stretching speed of 10 to 20 M / min under a stretching temperature of 150 to 260 캜, preferably at a stretching speed of 11 to 18 M / min under a stretching temperature of 200 to 250 캜 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 stretch uniformity in the transverse direction is lowered. If the biaxial stretching temperature exceeds 260 ° C If the stretching speed exceeds 20 M / min, there may be a problem that the untreated section occurs and the physical properties are lowered.

Next, the calcination in step 7 is carried out at a temperature of 350 ° C to 450 ° C, preferably 350 ° C to 450 ° C, while moving the stretched porous support on the conveyor belt at a speed of 10 to 18 M / min, preferably 13 to 17 M / A temperature of 380 ° C to 440 ° C, and more preferably, a temperature of 400 ° C to 435 ° C can be carried out, whereby the stretching ratio can be fixed and the strength improving effect can be obtained. When the firing temperature is less than 350 ° C., the strength of the porous support may be lowered. If the firing temperature is higher than 450 ° C., the fibril number may be decreased due to the underfatibility.

The porous support for a fuel cell electrolyte membrane of the present invention produced by performing the 7-step process has a stretching ratio (or aspect ratio) in a uniaxial (longitudinal) direction and a biaxial (width) direction of 1: 3.00 to 8.5, : 3.50 to 7.0, more preferably 1: 4.00 to 5.50, still more preferably 1: 4.20 to 5.00, and the uniaxial and biaxial stretching ratios (or aspect ratios) Mechanical properties, securing the optimum pore size of the support, and ensuring proper current flowability.

The prepared porous support may have an average pore size of 0.080 탆 to 0.200 탆, preferably 0.090 탆 to 0.180 탆, more preferably 0.095 탆 to 0.150 탆, still more preferably 0.100 to 0.140 탆. In addition, the porous support of the present invention may have an average porosity of 60% to 90%, more preferably 70% to 85%.

At this time, when the average pore size of the porous support is less than 0.080 mu m or the porosity is less than 60%, impregnation of the electrolyte in the support may be limited when the electrolyte is impregnated to prepare an electrolyte membrane using the support. If the average pore size exceeds 0.200 m or the porosity exceeds 90%, the porous support structure may be deformed when impregnated with the electrolyte, and the life of the product may be deteriorated due to deterioration of dimensional stability.

The porous support of the present invention manufactured by the above method may have an average thickness of 5 탆 to 25 탆, preferably an average thickness of 5 탆 to 20 탆, and more preferably 10 탆 to 20 탆.

When the porous support of the present invention is measured according to ASTM D 882, the uniaxial direction modulus and the biaxial direction modulus value can satisfy the following equation (1).

[Equation 1]

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

The porous support of the present invention may have a modulus in a uniaxial direction (longitudinal direction) of 40 MPa or more when measured according to ASTM D 882, preferably a uniaxial modulus of 50 MPa or more Preferably, the uniaxial direction modulus is 65 to 70 MPa. The modulus in the biaxial direction (width direction) may be 40 MPa or more, preferably, the modulus in the biaxial direction (width direction) may be 55 Mpa or more, more preferably 55 to 75 Mpa.

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

The porous support of the present invention having excellent mechanical properties, manufactured by the above-described method, comprises the steps of: 8) impregnating the porous support prepared by firing in step 7 into the fluorine-based ionomer solution; And drying and heat-treating the impregnated PTFE porous support.

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

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

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

The hollow portion of the hollow silica is a space for supporting the fluorine ionomer solution adsorbed and moved through the shell portion. The hollow portion may preferably have a hollow diameter of 5 to 100 nm, more preferably 5 to 50 nm . If the hollow diameter is less than 5 nm, the amount of the supported fluorine ionomer solution may be reduced. If the diameter exceeds 100 nm, the particle diameter of the hollow silica may exceed the desired range or cause collapse of the shell part. Based on 100 parts by weight of the fluorine-based ionomer solution, 0.05 to 5 parts by weight, and more preferably 1 to 3 parts by weight, of hollow silica. If the amount of the hollow silica is less than 0.05 part 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 insufficient. If the amount exceeds 5 parts by weight, the ratio of the closed pores in the porous support increases, When applied to an electrode assembly, the current flow rate may be lowered.

The fluorine-based ionomer solution may further include at least one moisture absorbent selected from zeolite, titania, zirconia, and montmorillonite.

The drying in step 9 may be performed at a temperature of 60 ° C to 100 ° C for 1 to 30 minutes, and the heat treatment may be performed at a temperature of 100 ° C to 200 ° C for 1 minute to 5 minutes. If the temperature of the drying step is less than 60 ° C, the liquid-repellency of the fluorinated ionomer solution impregnated into the porous support may be deteriorated. When the temperature exceeds 100 ° C, the electrolyte membrane and / The adhesion with the electrode may be deteriorated. If the heat treatment temperature is less than 100 ° C or less than 1 minute in the heat treatment step, the liquid reflux of the fluorinated ionomer solution impregnated in the porous support may deteriorate. If the temperature exceeds 200 ° C or the heat treatment time is 5 minutes The adhesion to the electrolyte membrane may be deteriorated when the support is adhered to the electrolyte membrane.

The heat-treated porous support of step 9 may have a closed pore volume of 90 vol% or more based on the total pore volume.

The fuel cell electrolyte membrane 10 shown in the schematic sectional view in FIG. 1 may be manufactured using the porous support of the present invention described above. Alternatively, the first electrolyte membrane 2 may be formed on one side of the porous support 1 , And the second electrolyte film (3) is formed on the other side of the support (1) to produce a fuel cell electrolyte membrane.

The fuel cell electrolyte membrane may have a weight coefficient of variation (CV1) of 40% or more, preferably 45% to 300%, and more preferably 60% to 140% of the following relational expression (1).

[Relation 1]

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

The weight variation coefficient is one of indicators that can be measured by measuring the weight change due to impregnation of the electrolyte membrane into the pores of the porous support after the electrolyte membrane is coated on the surface of the porous support before and after impregnating the porous support with the fluorine- , The larger the value is, the more the amount of the impregnated fluorine ionomer impregnated in the porous support is increased.

As described above, it can be seen that the impregnated amount of the electrolyte impregnated in the porous support is large because the weight coefficient of variation of the composite electrolyte membrane for a fuel cell according to the present invention satisfies 40% or more. The electrolyte membrane for a fuel cell according to the present invention has a volume shrinkage degree And the electrolyte impregnation amount is high.

The fuel cell electrolyte membrane produced by using the porous support of the present invention has a tensile strength and a modulus increasing effect. The fuel cell electrolyte membrane of the present invention has a modulus in the uniaxial (longitudinal) direction (longitudinal direction) when measured according to ASTM D 882 modulus) may be 50 MPa or more, and preferably the uniaxial direction modulus is 55 MPa or more, more preferably the uniaxial direction modulus is 55 to 100 MPa. The modulus in the biaxial direction (width direction) may be 50 MPa or more, preferably, the modulus in the biaxial direction (width direction) may be 53 MPa or more, more preferably 55 to 90 MPa.

The fuel cell electrolyte membrane prepared using the porous support of the present invention had a tensile strength in the uniaxial direction (longitudinal direction) of 45 MPa or more and a tensile strength in the biaxial direction (width direction) of 45 MPa And preferably the uniaxial tensile strength is 55 MPa or more, more preferably the uniaxial tensile strength is 56 to 90 MPa. The biaxial tensile strength may preferably be 50 to 85 MPa, and more preferably, the biaxial tensile strength may be 50 to 78 MPa.

The fuel cell electrolyte membrane of the present invention has a simpler structure as compared with the conventional fuel cell electrolyte membrane and can improve the interfacial characteristics when bonded to electrodes. In addition, since the thickness of the support can be designed to be thinner, the thickness of the electrolyte membrane can be thinned, thereby preventing delay of hydrogen ion transfer and improving the performance of the fuel cell.

The membrane-electrode assembly according to an embodiment of the present invention includes the steps of manufacturing the above-described fuel cell electrolyte membrane 10, as shown in a cross-sectional view schematically shown in FIG. 2, and forming a catalyst layer 22 on both surfaces of the electrolyte membrane for the fuel cell, 22 ', gas diffusion layers 21, 21'? And a step of bonding electrodes including the electrode substrate 23, 23 '.

Referring to FIG. 2, the membrane-electrode assembly according to an embodiment of the present invention includes an oxidizing electrode 20 and a reducing electrode 20 'positioned opposite to each other with a fuel cell electrolyte membrane 10 interposed therebetween . At this time, the oxidation electrode 20 and the reduction electrode 20 'include gas diffusion layers 21 and 21', catalyst layers 22 and 22 ', and electrode substrates 23 and 23', respectively.

The detailed description of the composite electrolyte membrane for a fuel cell will be made in reference to the above description.

The oxidation electrode 20 may include a gas diffusion layer 21 and an oxidation catalyst layer 22. The gas diffusion layer 21 may be provided to prevent rapid diffusion of fuel injected into the fuel cell and to prevent deterioration of ion conductivity. The gas diffusion layer 21 can control the diffusion rate of the 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 a formic acid solution, methanol, formaldehyde, or ethanol.

The oxidation catalyst layer 22 may include a conductive support and an ion conductive binder (not shown) as a layer into which the catalyst is introduced. In addition, 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, and may be, for example, platinum (Pt).

The oxidation catalyst layer 22 can be formed by an electroplating method, a spray method, a painting method, a doctor blade method, or a transfer method.

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

The reduction catalyst layer 22 'may include a conductive support and an ion conductive binder (not shown) as a layer into which the catalyst is introduced. 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. The main catalyst may be a metal catalyst, for example, platinum (Pt).

The reduction catalyst layer 22 'can 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 oxidation electrode 20, the composite electrolyte membrane 10 for a fuel cell, and the reduction electrode 20 ', respectively, and then pressing them together at a high temperature and a high pressure.

The step of joining the electrodes 20 and 20 'to both surfaces of the composite electrolyte membrane 10 for a fuel cell comprises: firstly, applying a gas diffusion layer forming material to one surface of the fuel cell electrolyte membrane 10 to form gas diffusion layers 21 and 21' &Apos;). ≪ / RTI >

The gas diffusion layers 21 and 21 'serve as current conductors between the composite electrolyte membrane 10 for a fuel cell and the catalyst layers 22 and 22', and serve as passages for gas as a reactant and water as a product. Accordingly, the gas diffusion layers 21 and 21 'may have a porous structure with a porosity of 20% to 90% so that the gas can pass through. The thickness of the gas diffusion layers 21, 21 'may be suitably adopted as needed, and may be, for example, 100 to 400 탆. 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 due to compression. Further, when the thickness of the gas diffusion layers 21 and 21 'exceeds 400 탆, it may become difficult to move the reactant gas.

The gas diffusion layers 21 and 21 'may include a carbon-based material and a fluororesin. Carbon nanowires, carbon nanowires, carbon nanowires, fullerenes (C60), carbon nanotubes, carbon nanotubes, carbon nanotubes, carbon nanowires, carbon nanowires, carbon nanowires, And Super P, but the present invention is not limited thereto. Examples of the fluororesin include polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polyvinyl alcohol, cellulose acetate, copolymers of polyvinylidene fluoride-hexafluoropropylene, styrene-butadiene heptane (SBR) ≪ RTI ID = 0.0 > and / or < / RTI >

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, at least one 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. Examples of the carbon-based support include graphite, carbon black, acetylene black, denka black, keehan black, activated carbon, mesoporous carbon, carbon nanotube, carbon nanofiber, carbon nanohorn, Wire, fullerene, and super P, for example.

The electrode substrate 23 and 23 'may be made of a conductive material selected from the group consisting of carbon paper, carbon cloth, and carbon felt. However, the present invention is not limited thereto, and a cathode electrode material applicable to a polymer electrolyte fuel cell All of the anode electrode materials are usable. The electrode substrate may be formed by a conventional deposition method and the catalyst layers 22 and 22 'may be formed on the electrode substrates 23 and 23', and then the catalyst layers 22 and 22 'may be formed on the gas diffusion layers 21 and 21' (22, 22 ') and the gas diffusion layers (21, 21') are in contact with each other.

Meanwhile, the fuel cell according to an embodiment of the present invention includes at least one electricity generating unit for generating electric energy through oxidation reaction of the fuel and oxidizing agent, and a fuel supply unit for supplying the fuel to the electricity generating unit. And an oxidant space portion for supplying an oxidant to the electricity generating portion.

The membrane-electrode assembly may include one or more electrodes, and a separator for supplying fuel and an oxidant to both ends of the membrane-electrode assembly is disposed to constitute an electricity generating unit. At least one of these electricity generating units may be gathered to form a stack.

At this time, the arrangement or the manufacturing method of the fuel cell can be variously applied to a polymer electrolyte fuel cell, so that it can be applied variously with reference to the prior art.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

[ Example ]

Example  One : PTFE  Preparation of Porous Support

23 parts by weight of naphtha as a liquid lubricant was mixed and stirred with 100 parts by weight of a PTFE fine powder having an average particle diameter of 570 탆 and uniformly dispersed to prepare a paste.

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

Next, the PTFE block was put into an extrusion die, and then subjected to pressure extrusion under a pressure of about 0.10 Ton / cm ² .

Next, rolling was performed using a rolling roll to produce an untreated tape having an average thickness of 850 占 퐉.

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

Next, the untreated tape from which the lubricant was removed was subjected to uniaxial stretching (longitudinal stretching) at a draw temperature of 280 DEG C and a stretching speed of 10 M / min at 6.5 times.

Next, the uniaxially stretched untreated tapes were subjected to biaxial stretching (widthwise stretching) at 30 times under the conditions of a stretching temperature of 250 占 폚 and a stretching speed of 10 M / min to prepare porous supports.

Next, the uniaxially and biaxially oriented porous supports were fired on the conveyor belt at a rate of 15 M / min at a temperature of 420 ° C to produce a PTFE porous support having an average thickness of 14 μm and an average pore size of 0.114 μm.

Example  2 ~ Example  3 and Comparative Example  1 ~ Comparative Example  2

The porous support prepared in the same manner as in Example 1 except that the porous support prepared by uniaxial and biaxial stretching in Example 1 was changed to the firing temperature as shown in Table 1 below to prepare PTFE porous supports, And Comparative Examples 1 and 2, respectively.

Example  4 ~ Example  6 and Comparative Example  3 ~ Comparative Example  6

Examples 4 to 6 and Comparative Examples 3 to 6 were prepared in the same manner as in Example 1 except that the PTFE porous support was prepared by varying the temperature during the uniaxial stretching or the temperature during biaxial stretching, Respectively.

Example  7 ~ Example  10 and Comparative Example  7 ~ Comparative Example  10

The PTFE porous support was prepared in the same manner as in Example 1 except that the stretching speed in the uniaxial stretching or the stretching speed in the biaxial stretching was changed as shown in Table 1 to obtain Examples 7 to 10 and Comparative Example 7 Respectively.

Examples 11 to 17 and Comparative Examples 11 to 15

The PTFE porous support was prepared in the same manner as in Example 1, except that uniaxial and biaxial orientation was performed under the same conditions as in Table 1 below.

division Plasticity
Temperature
(° C) Uniaxial stretching temperature
(° C) Biaxial stretching temperature
(° C) Uniaxial stretching speed
(M / min) Biaxial stretching speed
(M / min) Uniaxial stretching ratio
(Longitudinal direction) Biaxial stretching ratio
(Width direction) 1-axis and 2-axis elongation ratios
(Support stretching aspect ratio) Support
Average
thickness
(탆) Example 1 420 280 250 10 10 6.5 30 1: 4.62 14 탆 Example 2 440 280 250 10 10 6.5 30 1: 4.62 12 탆 Example 3 380 280 250 10 10 6.5 30 1: 4.62 17 탆 Example 4 420 260 250 10 10 6.5 30 1: 4.62 16 탆 Example 5 420 330 250 10 10 6.5 30 1: 4.62 13 탆 Example 6 420 280 260 10 10 6.5 30 1: 4.62 14 탆 Example 7 420 280 250 8 10 6.5 30 1: 4.62 14 탆 Example 8 420 280 250 11.5 10 6.5 30 1: 4.62 14 탆 Example 9 420 280 250 10 15 6.5 30 1: 4.62 16 탆 Example 10 420 280 250 10 18 6.5 30 1: 4.62 16 탆 Example 11 420 280 250 10 10 7 30 1: 4.29 12 탆 Example 12 420 280 250 10 10 8 36 1: 4.50 10 탆 Example 13 420 280 250 10 10 8 32 1: 4.00 11 탆 Example 17 420 280 250 10 10 6.5 45 1: 6.92 10 탆 Comparative Example 1 335 280 250 10 10 6.5 30 1: 4.62 18 탆 Comparative Example 2 460 280 250 10 10 6.5 30 1: 4.62 9 탆 Comparative Example 3 420 240 250 10 10 6.5 30 1: 4.62 15 탆 Comparative Example 4 420 365 250 10 10 6.5 30 1: 4.62 11 탆 Comparative Example 5 420 280 140 10 10 6.5 30 1: 4.62 17 탆 Comparative Example 6 420 280 290 10 10 6.5 30 1: 4.62 13 탆 Comparative Example 7 420 280 250 5.5 10 6.5 30 1: 4.62 12 탆 Comparative Example 8 420 280 250 14 10 6.5 30 1: 4.62 18 탆 Comparative Example 9 420 280 250 10 8 6.5 30 1: 4.62 11 탆 Comparative Example 10 420 280 250 10 22 6.5 30 1: 4.62 18 탆 Comparative Example 11 420 280 250 10 10 2.5 18 1: 7.20 27 탆 Comparative Example 12 420 280 250 10 10 2.5 20 1: 8.00 24 탆 Comparative Example 13 420 280 250 10 10 8 22 1: 2.75 16 탆 Comparative Example 14 420 280 250 10 10 6.5 14 1: 2.15 25 m Comparative Example 15 420 280 250 10 10 6.5 51 1: 7.85 7 탆

Experimental Example  One : PTFE  Measurement of Mechanical Properties of Porous Support

The average pore size, porosity, tensile strength and modulus of each of the porous supports prepared in Examples and Comparative Examples were measured, and the results are shown in Tables 2 and 3 below.

The average pore size and porosity were measured according to ASTM F316-03, the pressure was 0 to 70 psi, the solvent was galwick, and the dry up / wet up method was used (capillary flow meter, capillary flow porometer).

The tensile strength and the modulus were measured using a universal tester under the conditions of a test speed of 500 mm / min and an initial grip distance of 500 mm after making a straight specimen (width 10 mm, length 100 mm) according to the ASTM D 882 method. test machine.

division Average pore size (占 퐉) Porosity (%) Example 1 0.124 71.0 Example 2 0.152 78.7 Example 3 0.093 62.3 Example 4 0.117 69.7 Example 5 0.144 76.5 Example 6 0.131 72.1 Example 7 0.147 77.0 Example 8 0.115 68.8 Example 9 0.098 65.1 Example 10 0.083 61.2 Example 11 0.143 76.3 Example 12 0.155 79.6 Example 13 0.143 76.0 Example 17 0.153 77.7 Comparative Example 1 0.073 55.2 Comparative Example 2 0.260 90.4 Comparative Example 3 0.077 57.4 Comparative Example 4 0.215 87.2 Comparative Example 5 0.069 51.5 Comparative Example 6 0.233 88.0 Comparative Example 7 0.216 86.9 Comparative Example 8 0.073 53.1 Comparative Example 9 0.209 87.0 Comparative Example 10 0.077 52.9 Comparative Example 11 0.183 81.3 Comparative Example 12 0.196 84.2 Comparative Example 13 0.163 80.5 Comparative Example 14 0.165 81.7 Comparative Example 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 axes
(Width direction) 1 axis
(Longitudinal direction) 2 axes
(Width direction) Example 1 51 52 50 53 6.00% Example 2 48 50 51 49 3.92% Example 3 64 68 66 65 1.52% Example 4 58 54 60 59 1.67% Example 5 47 44 50 46 8.00% Example 6 53 50 50 53 6.00% Example 7 47 46 48 50 4.17% Example 8 54 58 53 55 3.77% Example 9 64 61 66 63 4.55% Example 10 68 63 68 65 4.41% Example 11 63 49 61 53 13.11% Example 12 62 57 60 55 8.33% Example 13 65 53 66 54 18.18% Example 17 47 63 50 61 22.00% Comparative Example 1 78 71 75 73 2.67% Comparative Example 2 41 37 39 41 5.13% Comparative Example 3 73 69 71 65 8.45% Comparative Example 4 47 45 45 41 8.89% Comparative Example 5 77 79 81 85 4.94% Comparative Example 6 42 46 41 46 12.20% Comparative Example 7 37 33 40 36 10.00% Comparative Example 8 69 74 71 77 8.45% Comparative Example 9 41 43 42 43 2.38% Comparative Example 10 66 70 67 69 2.99% Comparative Example 11 27 43 31 44 41.94% Comparative Example 12 22 47 28 45 60.71% Comparative Example 13 81 23 78 26 66.67% Comparative Example 14 53 27 51 32 37.25% Comparative Example 15 38 63 37 66 78.38% (1) Differences between 1 and 2 axis modulus values = (1 axis direction modulus - 2 axis direction modulus) / (1 axis direction modulus) 100%

Referring to Table 2, it was confirmed that the supports of Examples 1 to 17 had an average pore size of 0.08 to 0.20 μm and a porosity of 60 to 80%. On the contrary, in Comparative Example 1, Comparative Example 3, Comparative Example 5, and Comparative Example 8, the average pore size was less than 0.08 탆 and less than 60%. In Comparative Example 4, Comparative Example 6, Comparative Example 7, Comparative Example 9 and Comparative Example 15, the average pore size exceeded 0.20 탆.

As shown in Table 3, in Examples 1 to 17, the tensile strengths were more than 40 Mpa in both the first and second axes, and the modulus was more than 40 Mpa in both the first and second axes.

In contrast, the biaxial tensile strength and uniaxial modulus of Comparative Example 2 were as low as less than 40 MPa, while the uniaxial tensile strength and uniaxial modulus of Comparative Example 11, Comparative Example 12 and Comparative Example 15 were lower than 40 MPa Respectively.

In Comparative Examples 13 and 14, biaxial tensile strength and biaxial modulus were lower than 40 Mpa.

Manufacturing example  1: Preparation of electrolyte membrane

1 part by weight of spherical hollow silica having an average particle diameter of 50 nm was mixed with 100 parts by weight of Nafion, which is a fluorine-based ionomer, to prepare a Nafion solution

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

Manufacturing example  2 to 3 and Comparative Manufacturing Example  1-2

The porous support impregnated with electrolyte was prepared in the same manner as in Preparation Example 1 except that the kinds of supports were changed as shown in Table 4 below.

Experimental Example  2: Measurement of weight variation coefficient

The weight variation coefficient (CV1,%) was calculated from the following equation (2) by measuring the weight of the PTFE porous support before preparation of the electrolytic solution and the electrolytic solution prepared in the comparative preparation example, and the weight of the electrolyte membrane coated with the electrolyte layer on the support after impregnation .

[Relation 1]

(CV1,%) = (thickness of porous support after electrolytic treatment - weight of porous support before electrolyte treatment) / (weight of porous support before electrolytic treatment) 100%

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

As shown in Table 4, in the case of Production Examples 1 to 3, it was confirmed that the weight change coefficient was in the range of 40% or more, preferably 60% to 300%. On the contrary, when the porous support of Comparative Example 1, Comparative Example 3, Comparative Example 5 and Comparative Example 8, in which the average pore size of the porous support was less than 0.08 탆, had excellent tensile strength and modulus, And the weight variation coefficient value was less than 40%.

In addition, when the porous support of Comparative Example 6 and Comparative Example 9 was used, the weight variation coefficient was as high as 300% or more.

Referring to Table 4, it can be seen that the weight variation coefficients of Examples 1 to 3 are higher than those of Comparative Examples 1 and 2. Therefore, it can be confirmed that Production Examples 1 to 3 according to one embodiment of the present invention have more electrolyte retained.

delete

Experimental Example 3: Electrolyte Membrane  Tensile strength and Modulus  Measure

(Aquivion ( ^TM )) electrolyte was applied to one side of the PTFE porous support prepared in Example 1 using a film applicator, followed by drying at 90 DEG C for 10 minutes. On the opposite side of the porous support, the same electrolyte After the application, it was dried at 90 ° C for 10 minutes and then heat-treated at 150 ° C for 10 minutes to prepare a three-layered electrolyte membrane including a PTFE porous support layer.

A three-layer electrolyte membrane including a PTFE porous support layer was prepared by using the porous supports of Example 5, Example 10, Example 15, Comparative Example 6, and Comparative Example 9 in the same manner.

In addition, an electrolyte membrane having a three-layer structure as shown in Fig. 1 was prepared in the same manner using a conventional PTFE porous support (monoaxial stretching ratio 2.5 times, biaxial stretching ratio 10 times, manufacturer: Sawafron Tech).

The tensile strength and modulus of the electrolyte membrane thus prepared 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) In the biaxial direction (TD direction, Mpa) 1 axis direction (MD direction, Mpa) In the biaxial direction (TD direction, Mpa) Example 1 60 63 63 69 Example 5 58 51 57 55 Example 10 78 71 96 84 Existing PTFE porous support 47 34 35 15 Comparative Example 6 43 44 44 47 Comparative Example 9 41 42 42 45

As a result of measuring the physical properties of Table 5, the electrolyte membrane prepared using the conventional PTFE porous support showed significantly lower mechanical properties as compared with the Examples. In contrast, 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 Comparative Example 6 and Comparative Example 9 in which the amount of electrolyte impregnation in the porous support was high and the weight variation coefficient exceeded 300%, it was confirmed that there was a problem in that the modulus was greatly decreased as well as the tensile strength of the electrolyte membrane And the effect of increasing the mechanical properties due to the preparation of the electrolyte membrane using the porous support was very weak. In contrast, in Examples 1, 5 and 10, the tensile strength and modulus of the electrolyte membrane were increased compared with the tensile strength and modulus of the porous support.

It can be seen from the above Examples and Experimental Examples that the PTFE porous support prepared by the method of the present invention has not only good mechanical properties but also excellent electrolyte impregnation amount in the inside of the support. In addition, it is possible to provide an electrolyte membrane for a fuel cell having excellent mechanical properties using the PTFE porous support of the present invention, and further, to provide a membrane-electrode assembly and a fuel cell for a fuel cell with excellent efficiency.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that the present invention, Various modifications and variations are possible.

1: Porous support 2: First electrolyte membrane 3: Second electrolyte membrane
10: fuel cell electrolyte membrane 21: gas diffusion layer 22: catalyst layer
23: electrode substrate 20: electrode

Claims (15)

delete delete delete A PTFE porous support having an average pore size of 0.090 to 0.180 탆 and an average porosity of 60 to 79.6%
The PTFE porous support has a stretching ratio of 1: 4.0 to 7.0 in a uniaxial direction (longitudinal direction) and a biaxial direction (width direction)
The modulus in the uniaxial direction (longitudinal direction) is 48 to 75 MPa and the modulus in the biaxial direction (width direction) is 46 to 75 MPa when measured according to ASTM D 882,
Wherein the uniaxial direction modulus and the biaxial direction modulus value satisfy the following Equation 1: < EMI ID = 1.0 >
[Equation 1]
0 ≤ │ (1 axis direction modulus - 2 axis direction modulus) / (1 axis direction direction modulus) ⅹ100% │ ≤ 40%
A step of mixing a PTFE powder and a liquid lubricant and stirring to prepare a paste;
Aging the paste at a temperature of 30 ° C to 70 ° C for 12 to 24 hours;
Compressing the aged paste to prepare a PTFE block, pressurizing and extruding the PTFE block at a pressure of 0.069 to 0.200 Ton / cm ² to produce an untreated tape;
Drying the uncured tape, and then removing the liquid lubricant;
Stretching in uniaxial direction at a stretching temperature of 260 ° C to 350 ° C and a rate at which the untreated tape from which the lubricant has been removed is stretched at a rate of 6 to 12 M / min;
A stretching step in a biaxial direction under a stretching temperature of 150 ° C to 260 ° C and a uniaxially stretched untreated tape at a stretching speed of 10 to 20 M / min; And
Firing step 7,
The prepared PTFE porous support had a stretching ratio in the uniaxial (longitudinal) direction and the biaxial (width) direction of 1: 4.0 to 7.0, an average pore size of 0.090 to 0.180 탆 and an average porosity of 60 to 79.6% Wherein the porous support is a porous support.
delete delete 6. The method of claim 5,
Wherein the firing step in the seventh step is performed at a temperature of 350 ° C to 450 ° C.
The method of claim 5, further comprising the steps of: 8) impregnating the electrolyte solution with the porous support prepared by performing the 7-step process; And
And drying and heat-treating the impregnated PTFE porous support. 9. The method of claim 7, wherein the porous support is impregnated with an organic solvent.
The membrane-electrode assembly according to claim 4, comprising a highly oriented porous support for fuel cell electrolyte membrane.
An electricity generating unit including the membrane-electrode assembly and the separator of claim 10 and generating electricity through an electrochemical reaction between the fuel and the oxidant;
A fuel supply unit for supplying fuel to the electricity generation unit; And
An oxidant supply unit supplying the oxidant to the generator; ≪ / RTI > delete delete delete delete

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