WO2019027069A1 - Fuel cell electrolyte reinforced membrane and manufacturing method therefor - Google Patents

Abstract

The present invention relates to a fuel cell electrolyte reinforced membrane, a membrane-electrode assembly comprising same and a fuel cell, and more specifically, to an invention that may provide a fuel cell material and a fuel cell exhibiting improved performance by providing a fuel cell electrolyte reinforced membrane comprising, from the cross-sectional view of the electrolyte reinforced membrane, a first electrolyte layer formed on one lateral surface of a porous support; and a second electrolyte layer formed on the other lateral surface. By introducing the porous support exhibiting improved mechanical properties by being manufactured under particular conditions such as draw ratio and drawing speed, the mechanical properties of the electrolyte reinforced membrane may be greatly improved, and the difference in mechanical properties between a first axial direction (length direction) and a second axial direction (thickness direction) may be minimized.

Description

Fuel cell electrolyte-reinforced membrane and manufacturing method thereof

The present invention relates to a fuel cell electrolyte-reinforced membrane, and more particularly, to an electrolyte-reinforced membrane for a fuel cell, wherein a porous support used for an electrolyte membrane for fuel cells is introduced into a specific support to greatly improve mechanical properties, A fuel cell including the same, and a method of manufacturing the same.

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, There is a problem in that there is a difference in physical properties between the longitudinal direction and the thickness direction, and there is a problem in that economical efficiency and commerciality are poor due to a high defect rate in the production of the support.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the problems described above. It is an object of the present invention to provide a porous support which is produced under specific conditions such as stretching ratio and stretching speed, ) In which the difference in physical properties between the fuel cell and the electrolyte membrane is minimized. The present invention also provides a membrane-electrode assembly including the fuel cell electrolyte-reinforced membrane, and a fuel cell including the membrane-electrode assembly.

According to an aspect of the present invention, there is provided a fuel cell electrolyte-reinforced membrane including a first electrolyte layer formed on one side of a porous support and a first electrolyte layer formed on another side of the porous support, And a second electrolyte layer formed thereon.

As a preferred embodiment of the present invention, the fuel cell electrolyte-reinforced membrane of the present invention can satisfy the following equation (1) when measuring according to ASTM D 822, the uniaxial direction modulus and the biaxial direction modulus difference.

[Equation 1]

0 ≤ (uniaxial direction modulus of electrolyte-reinforced membrane - biaxial direction modulus of electrolyte-reinforced membrane) / (uniaxial direction modulus of electrolyte-reinforced membrane) × 100% ≤ ≤ 30%

In one preferred embodiment of the present invention, the fuel cell electrolyte membrane of the present invention may have a uniaxial modulus of 80 MPa or more and a biaxial modulus of 80 MPa or more when measured according to ASTM D 822.

As a preferred embodiment of the present invention, the fuel cell electrolyte-reinforced membrane of the present invention can satisfy the following Equation 2 in the uniaxial tensile strength and biaxial tensile strength difference when measured according to ASTM D 822.

[Equation 2]

0 ≤ (Uniaxial Tensile Strength of Electrolyte Reinforced Film - Biaxial Tensile Strength of Electrolyte Reinforced Film) / (Uniaxial Tensile Strength of Electrolyte Reinforced Film) × 100% ≤ ≤ 20%

As a preferred embodiment of the present invention, the fuel cell electrolyte 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) of 50 MPa or more.

As a preferred embodiment of the present invention, the fuel cell electrolyte-reinforced membrane may have a weight coefficient of variation (CV1) of the following relational expression 1 of 20% or more.

[Relation 1]

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

As a preferred embodiment of the present invention, the fuel cell electrolyte-reinforced membrane may have an average thickness of 1 탆 to 20 탆, and the first electrolyte layer and the second electrolyte layer may independently have an average thickness of 1 탆 to 15 탆 have.

In one preferred embodiment of the present invention, the porous support has a modulus in a uniaxial direction (longitudinal direction) of 40 MPa or more and a modulus in a biaxial direction (width direction) of 40 MPa or more when measured according to ASTM D 822 .

In one preferred embodiment of the present invention, the porous support 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, as measured according to ASTM D 882 have.

In one preferred embodiment of the present invention, when the porous support is measured according to ASTM D 822, the uniaxial direction modulus and the biaxial direction modulus value can satisfy the following equation (3).

[Equation 3]

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 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 may have a uniaxial (longitudinal) stretching ratio of 6 to 9.5 times and a biaxial (width) stretching ratio of 25 to 45 times.

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

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

Another object of the present invention is to provide a method of preparing the various types of fuel cell electrolyte-reinforced membranes described above, comprising the steps of: impregnating a porous support with a fluorine ionomer solution; And drying and heat treating the impregnated PTFE porous support.

In one preferred embodiment of the present invention, the fluorine-based ionomer solution 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.

In one preferred embodiment of the present invention, the porous support includes a first step of mixing 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, the lubricant is a liquid lubricant, and 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, At least one selected from liquid paraffin, naphtha and white oil can be used.

In one preferred embodiment of the present invention, the aging of the two stages may be carried out at a temperature of 30 to 70 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 three stages can be carried out by calendering at an oil pressure of 5 to 10 MPa and at 50 to 100 캜.

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.

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.

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

In one preferred embodiment of the present invention, the membrane-electrode assembly (MEA) of the present invention comprises the fuel cell electrolyte-reinforced 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 reinforced membrane of the present invention ensures an optimal stretch ratio and elongation speed, and can be manufactured with a very low defective ratio, thereby being excellent in economy and commerciality, and securing excellent mechanical properties. As a result, Thereby improving the performance of the fuel cell by reducing the total thickness of the fuel cell electrolyte-reinforced membrane.

1 is a schematic view of a fuel cell electrolyte-reinforced 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.

Hereinafter, the fuel cell electrolyte-reinforced membrane of the present invention will be described in more detail.

The fuel cell electrolyte-reinforced membrane of the present invention is simpler in structure than the conventional fuel cell electrolyte-reinforced membrane and can improve the interfacial property when bonded to an electrode. In addition, it is an electrolyte reinforced membrane for a fuel cell that can be designed to have a thinner support and can prevent hydrogen ion transmission delay as the thickness of the electrolyte membrane becomes thinner, and can improve the performance of the fuel cell.

The fuel cell electrolyte-reinforced membrane of the present invention has an electrolyte membrane on the surface of the porous support. As shown in a schematic cross-sectional view in FIG. 1, the first electrolyte membrane 2 is formed on one side of the porous support 1 , And a second electrolyte layer (3) is formed on the other side of the support (1).

In the fuel cell electrolyte-reinforced membrane of the present invention, when measured according to ASTM D 822, the uniaxial modulus and biaxial modulus difference of the electrolyte-reinforced membrane can satisfy Equation 1 below.

[Equation 1]

0 ≤ (uniaxial direction modulus of electrolyte-reinforced membrane - biaxial direction modulus of electrolyte-reinforced membrane) / (uniaxial direction modulus of electrolyte-reinforced membrane) × 100% ≤ 30%, preferably 0 ≤ Directional modulus - biaxial modulus of the electrolyte-reinforced membrane) / (uniaxial modulus of the electrolyte-reinforced membrane) x 100% ≤ 15%, more preferably 0 ≤ (biaxial modulus of the electrolyte- Directional modulus) / (uniaxial modulus of the electrolyte-reinforced membrane) x 100% ≤ 10%

The electrolyte reinforced membrane of the present invention may have a modulus in a uniaxial direction (longitudinal direction) of 80 MPa or more, preferably a uniaxial modulus in a range of 85 to 145 MPa Preferably, the uniaxial direction modulus is 95 to 140 MPa. The modulus in the biaxial direction (width direction) is 80 MPa or more, preferably, the modulus in the biaxial direction (width direction) is 85 to 135 MPa, more preferably 95 to 135 MPa.

In the fuel cell electrolyte-reinforced membrane of the present invention, when measured according to ASTM D 822, the uniaxial tensile strength and biaxial tensile strength difference of the electrolyte-reinforced membrane can satisfy the following equation (2).

[Equation 2]

0 ≤ (uniaxial tensile strength of the electrolyte-reinforced membrane - biaxial tensile strength of the electrolyte-reinforced membrane) / (uniaxial tensile strength of the electrolyte-reinforced membrane) x 100% ≤ 20%, preferably 0 ≤ Axis direction tensile strength of the electrolyte-reinforced film) / (tensile strength in uniaxial direction of the electrolyte-reinforced film) 占 100% | 16%, more preferably 0? (Uniaxial tensile strength of the electrolyte- Strength - Tensile strength in the biaxial direction of the electrolyte-reinforced membrane) / (Tensile strength in the uniaxial direction of the electrolyte-reinforced membrane) 100% | 9%

The electrolyte-reinforced membrane of the present invention may have a tensile strength in a uniaxial direction (longitudinal direction) of 50 MPa or more and a tensile strength in a biaxial direction (width direction) of 50 MPa or more when measured according to ASTM D 822, The uniaxial tensile strength may be 60 to 95 MPa, and more preferably the uniaxial tensile strength may be 66 to 90 MPa. The biaxial tensile strength may be 50 Mpa or more, and preferably the biaxial tensile strength may be 60 to 92 Mpa, and more preferably, the biaxial tensile strength may be 65 to 88 Mpa.

The fuel cell electrolyte-reinforced membrane of the present invention comprises the steps of: impregnating a porous support with a fluorine ionomer solution; And drying and heat treating the impregnated PTFE porous support.

The fluorine-based ionomer solution 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 of 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 diameter of 10 to 300 nm, and more preferably 10 nm 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 have a hollow diameter of 5 nm to 100 nm, more preferably 5 nm 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 hollow silica is less than 0.05 parts by weight based on 100 parts by weight of the fluorine-containing 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.

Next, the PTFE porous support impregnated with the fluorine-based ionomer solution is taken out and dried at 60 to 100 ° C. for 1 to 30 minutes. The heat treatment is performed at 100 ° C. to 200 ° C. for 1 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 porous support in the heat-treated electrolyte-reinforced membrane may have a volume of occluded pores of 90% by volume or more based on the total pore volume.

The porous support used for preparing the electrolyte-reinforced membrane of the present invention can be produced by the following method.

The porous support may include a first step of mixing and stirring 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 for 12 to 24 hours, preferably aged at a temperature of 35 to 60 for 16 to 20 hours can do. 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 / It is possible to carry out the heat treatment at a temperature of 380 ° C to 440 ° C, more preferably 400 ° C to 435 ° C, thereby fixing the stretching ratio and improving the strength. 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 manufactured 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, May be 1: 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 stretch ratios (or aspect ratios) It is preferable from the viewpoints of high 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 produced 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 measured according to ASTM D 822, the porous support prepared by this method can satisfy the following equation (3) in the uniaxial direction modulus and biaxial direction modulus value.

[Equation 3]

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% ≤ 26%

The porous support may have a modulus in a uniaxial direction (longitudinal direction) of 40 MPa or more, preferably a uniaxial modulus of 50 MPa or more, more preferably, The uniaxial direction modulus may be 52 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 45 MPa or more, more preferably 45 to 72 MPa.

The porous support used in 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, as measured according to ASTM D882, , The uniaxial tensile strength may be 50 MPa or more, and more preferably the uniaxial tensile strength may be 54 to 67 MPa. Preferably, the biaxial tensile strength is 45 Mpa or more, and more preferably the biaxial tensile strength is 48 to 68 Mpa.

The membrane-electrode assembly according to a preferred embodiment of the present invention includes the steps of manufacturing the above-described fuel cell electrolyte-enhanced membrane 10, as shown in the sectional view schematically shown in FIG. 2, 22, 22 '), the gas diffusion layers 21, 21', and 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 reinforcing film 10 therebetween do. 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 bonding of the electrodes 20 and 20 'to both surfaces of the composite electrolyte membrane 10 for a fuel cell may be performed by first applying a gas diffusion layer forming material to one surface of the fuel cell electrolyte reinforced membrane 10 to form gas diffusion layers 21, 21 '). ≪ / 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 μm 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 due to compression. In addition, 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 6.7 times under the conditions of a stretching temperature of 280 占 폚 and a stretching speed of 10 M / min.

Next, uniaxially stretched untreated tapes were subjected to biaxial stretching (stretching in the transverse direction) at a draw temperature of 250 DEG C and a stretching speed of 10 M / min at 31 times 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 DEG C to prepare a PTFE porous support having an average thickness of 13.6 mu m and an average pore size of 0.112 mu m.

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.

Example  11 ~ Example  15 and Comparative Example  11 ~ Comparative Example  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	Firing temperature (캜)	Uniaxial stretching temperature (占 폚)	Biaxial stretching temperature (占 폚)	Uniaxial stretching speed (M / min)	Biaxial stretching speed (M / min)	Uniaxial stretching ratio (longitudinal direction)	Biaxial stretching ratio (width direction)	The uniaxial and biaxial draw ratio (support elongation aspect ratio)	Support average thickness (탆)
Example 1	420	280	250	10	10	6.7	31	1: 4.63	13.6 탆
Example 2	440	280	250	10	10	6.7	31	1: 4.63	11.8 탆
Example 3	380	280	250	10	10	6.7	31	1: 4.63	17.1 탆
Example 4	420	260	250	10	10	6.7	31	1: 4.63	15.9 탆
Example 5	420	330	250	10	10	6.7	31	1: 4.63	12.9 탆
Example 6	420	280	260	10	10	6.7	31	1: 4.63	13.7 탆
Example 7	420	280	250	8	10	6.7	31	1: 4.63	13.6 탆
Example 8	420	280	250	11.5	10	6.7	31	1: 4.63	13.6 탆
Example 9	420	280	250	10	15	6.7	31	1: 4.63	16.1 탆
Example 10	420	280	250	10	18	6.7	31	1: 4.63	16 탆
Example 11	420	280	250	10	10	7	31	1: 4.29	12.2 탆
Example 12	420	280	250	10	10	8	36	1: 4.50	9.7 탆
Example 13	420	280	250	10	10	8	32	1: 4.00	10.8 탆
Example 14	420	280	250	10	10	3.5	31	1: 8.57	17.8 탆
Example 15	420	280	250	10	10	9	31	1: 3.33	9.8 탆
Example 16	420	280	250	10	10	6.7	18	1: 2.77	17.9 탆
Example 17	420	280	250	10	10	6.7	45	1: 6.92	9.8 탆
Comparative Example 1	335	280	250	10	10	6.7	31	1: 4.63	18 탆
Comparative Example 2	460	280	250	10	10	6.7	31	1: 4.63	8.9 탆
Comparative Example 3	420	240	250	10	10	6.7	31	1: 4.63	14.8 탆
Comparative Example 4	420	365	250	10	10	6.7	31	1: 4.63	10.9 탆
Comparative Example 5	420	280	140	10	10	6.7	31	1: 4.63	17.1 탆
Comparative Example 6	420	280	290	10	10	6.7	31	1: 4.63	12.8 탆
Comparative Example 7	420	280	250	5.5	10	6.7	31	1: 4.63	11.8 탆
Comparative Example 8	420	280	250	14	10	6.7	31	1: 4.63	18.1 m
Comparative Example 9	420	280	250	10	8	6.7	31	1: 4.63	10.7 탆
Comparative Example 10	420	280	250	10	22	6.7	31	1: 4.63	18.1 m
Comparative Example 11	420	280	250	10	10	2.5	18	1: 7.20	27.2 탆
Comparative Example 12	420	280	250	10	10	2.5	20	1: 8.00	23.8 탆
Comparative Example 13	420	280	250	10	10	8	22	1: 2.75	15.9 탆
Comparative Example 14	420	280	250	10	10	6.7	14	1: 2.15	24.7 탆
Comparative Example 15	420	280	250	10	10	6.7	51	1: 7.85	6.8 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	0.121	71.3
Example 2	0.149	79.1
Example 3	0.091	63.6
Example 4	0.150	70.2
Example 5	0.143	78.3
Example 6	0.130	74.2
Example 7	0.145	78.1
Example 8	0.117	70.9
Example 9	0.095	68.3
Example 10	0.090	63.1
Example 11	0.140	77.4
Example 12	0.147	79.9
Example 13	0.188	76.5
Example 14	0.107	68.7
Example 15	0.151	79.6
Example 16	0.125	75.0
Example 17	0.151	78.3
Comparative Example 1	0.072	56.1
Comparative Example 2	0.255	91.6
Comparative Example 3	0.073	58.3
Comparative Example 4	0.213	88.1
Comparative Example 5	0.071	53.5
Comparative Example 6	0.229	88.2
Comparative Example 7	0.223	87.1
Comparative Example 8	0.076	54.3
Comparative Example 9	0.216	89.6
Comparative Example 10	0.076	54.3
Comparative Example 11	0.177	83.1
Comparative Example 12	0.186	84.6
Comparative Example 13	0.173	82.2
Comparative Example 14	0.164	83.7
Comparative Example 15	0.221	91.1

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	52	54	52	55	5.77%
Example 2	51	53	53	51	3.77%
Example 3	66	71	68	69	1.47%
Example 4	60	55	62	61	1.61%
Example 5	50	45	52	46	11.54%
Example 6	55	52	54	56	3.70%
Example 7	51	49	53	52	1.89%
Example 8	57	63	55	57	3.64%
Example 9	67	65	68	67	1.47%
Example 10	71	67	68	67	1.47%
Example 11	66	53	66	57	13.64%
Example 12	64	61	63	59	6.35%
Example 13	66	57	68	60	11.76%
Example 14	47	75	50	71	42.00%
Example 15	76	45	73	48	34.25%
Example 16	55	43	58	45	22.41%
Example 17	51	64	55	67	21.82%
Comparative Example 1	83	74	77	76	1.30%
Comparative Example 2	43	35	41	37	9.76%
Comparative Example 3	75	71	74	69	6.76%
Comparative Example 4	50	47	48	45	6.25%
Comparative Example 5	80	78	79	76	3.80%
Comparative Example 6	43	45	44	49	11.36%
Comparative Example 7	40	31	37	34	8.11%
Comparative Example 8	74	71	72	76	5.56%
Comparative Example 9	43	45	44	49	11.36%
Comparative Example 10	68	72	70	73	4.29%
Comparative Example 11	30	44	33	46	39.39%
Comparative Example 12	25	50	31	49	58.06%
Comparative Example 13	78	27	76	31	59.21%
Comparative Example 14	55	25	53	27	49.06%
Comparative Example 15	33	58	35	63	80.00%
(1) Difference 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 占 폚 for 3 minutes to prepare a porous support impregnated with an electrolyte having a thickness of 15 占 퐉.

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

(1) The weight of the PTFE porous support before the electrolyte impregnation prepared in Production Example and Comparative Preparation Example and the weight of the electrolyte membrane coated with the electrolyte layer on the support after electrolyte impregnation were measured, and the weight variation coefficient (CV1,%) Respectively.

[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	Weight before electrolyte impregnation (g)	Weight after electrolyte impregnation (g)	Weight variation coefficient (%)
Production Example 1	Example 1	8.5	10.7	28.10
Production Example 2	Example 3	13.3	17.4	30.63
Production Example 3	Example 12	4.1	5.1	22.23
Comparative Preparation Example 1	Comparative Example 1	16.9	18.1	7.04
Comparative Production Example 2	Comparative Example 3	12.5	14.2	13.51
Comparative Production Example 3	Comparative Example 5	13.2	14.7	11.30
Comparative Production Example 4	Comparative Example 6	3.2	3.8	17.56
Comparative Preparation Example 5	Comparative Example 8	17.7	19.0	7.34
Comparative Preparation Example 6	Comparative Example 9	2.3	2.6	9.18
Comparative Preparation Example 7	Comparative Example 10	17.7	18.8	6.21

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 20% or more, preferably 22% to 40%. 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 20%.

In addition, Comparative Preparation Example 4 and Comparative Preparation Examples 6 to 7, which used porous supports having an appropriate range of mechanical properties, showed a too low weight variation coefficient value, indicating that the impregnation amount was small.

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.

Experimental Example 3: electrolyte Reinforced membrane  Tensile strength and Modulus  Measure

An electrolyte-reinforced membrane was prepared in the same manner as in Preparation Example 1 except that the electrolyte-reinforced membranes were prepared by different porous supports as shown in Table 5 to prepare electrolyte membranes having a three-layer structure including a PTFE porous support layer.

In addition, an electrolyte reinforced membrane having a three-layer structure as shown in Fig. 1 was prepared by using the 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 822, and the results are shown in Table 5 below.

division	Porous support	The tensile strength						Modulus
		1 axis direction (MD direction, Mpa)	In the biaxial direction (TD direction, Mpa)	1 axis, 2 axis deviation (%)	1 axis direction (MD direction, Mpa)	In the biaxial direction (TD direction, Mpa)	1 axis, 2 axis deviation (%)
Production Example 1	Example 1	72	69	4.17	127	115	9.45
Production Example 3	Example 3	80	84	5.00	114	123	7.89
Production Example 5	Example 5	71	66	7.04	106	121	14.15
Production Example 7	Example 7	69	68	1.45	108	107	0.93
Production Example 10	Example 10	88	84	4.55	120	118	1.67
Production Example 12	Example 12	77	75	2.60	107	108	0.93
Production Example 15	Example 15	89	75	15.73	139	109	21.58
Comparative Preparation Example 8	Existing PTFE porous support	43	28	34.88	70	42	40.00
Comparative Preparation Example 9	Comparative Example 6	49	33	32.65	73	42	36.99
Comparative Preparation Example 10	Comparative Example 9	46	32	30.43	65	38	35.38

The results of the physical properties measurement of Table 5 show that the electrolyte-reinforced membrane (Comparative Preparation Example 8) prepared using the conventional PTFE porous support has significantly lower mechanical properties as compared to Production Example 1 and the like. On the contrary, in the case of the electrolyte membrane prepared using the PTFE porous support of the examples, the modulus tended to increase greatly.

In Comparative Production Example 9 and Comparative Production Example 10, it was confirmed that there was a problem that not only the tensile strength of the electrolyte membrane but also the modulus were significantly lowered as compared with the production example, and the mechanical properties of the electrolyte membrane using the porous support were increased The effect was very weak. On the other hand, in Examples 1, 3, 5, 10, 12 and 15, the tensile strength and modulus of the electrolyte membrane were increased in comparison with the tensile strength and modulus of the porous support.

On the other hand, in the case of the production example, the uniaxial and biaxial tensile strength deviations were 20% or less, and the uniaxial and biaxial modulus deviations were 30% or less.

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.

[Description of Symbols]

1: porous support 2: first electrolyte layer 3: second electrolyte layer

10: Fuel cell electrolyte strengthening film 21: Gas diffusion layer 22: Catalyst layer

23: electrode substrate 20: electrode

Claims (14)

1. A first electrolyte layer formed on one side of the porous support and a second electrolyte layer formed on the other side of the electrolyte-enhanced membrane,

   Wherein the uniaxial modulus and the biaxial modulus difference of the electrolyte-reinforced membrane satisfy the following equation (1) when measured according to ASTM D 822: " (1) "

   [Equation 1]

   0 ≤ (uniaxial direction modulus of electrolyte-reinforced membrane - biaxial direction modulus of electrolyte-reinforced membrane) / (uniaxial direction modulus of electrolyte-reinforced membrane) × 100% ≤ ≤ 30%
2. The fuel cell electrolyte-reinforced membrane according to claim 1, wherein, when measured according to ASTM D 822, the uniaxial tensile strength and biaxial tensile strength difference of the electrolyte-reinforced film satisfies the following equation (2).

   [Equation 2]

   0 ≤ (Uniaxial Tensile Strength of Electrolyte Reinforced Film - Biaxial Tensile Strength of Electrolyte Reinforced Film) / (Uniaxial Tensile Strength of Electrolyte Reinforced Film) × 100% ≤ ≤ 20%
3. The fuel cell according to claim 1, wherein the electrolyte membrane has a uniaxial (longitudinal) modulus of 80 MPa or more and a biaxial (width direction) modulus of 80 MPa or more when measured according to ASTM D 822 Reinforced membrane.
4. The fuel cell according to claim 1, characterized in that the tensile strength in the uniaxial direction (longitudinal direction) of the electrolyte-reinforced membrane is 50 MPa or more and the tensile strength in the biaxial direction (width direction) is 50 MPa or more when measured according to ASTM D 822 Battery electrolyte toughening film.
5. The porous support according to claim 1, wherein the porous support 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 as measured according to ASTM D 822 Fuel cell electrolyte strengthening membrane.
6. The porous support according to claim 1, wherein the porous support has a modulus in a uniaxial direction (longitudinal direction) of 40 MPa or more and a modulus in a biaxial direction (width direction) of 40 MPa or more when measured according to ASTM D 822 A fuel cell electrolyte toughening membrane.
7. The fuel cell electrolyte-reinforced membrane according to claim 1, wherein the porous support is a polytetrafluoroethylene (PTFE) porous support having an average pore size of 0.080 탆 to 0.200 탆 and an average porosity of 60% to 90%.
8. The fuel cell electrolyte enhanced membrane according to claim 1, wherein the porous support has an average thickness of 1 탆 to 20 탆, and the first electrolyte layer and the second electrolyte layer independently have an average thickness of 1 탆 to 15 탆.
9. Impregnating the porous support with a fluorine ionomer solution; And

   Drying and heat treating the impregnated PTFE porous support,

   The porous support may include a first step of mixing and stirring the PTFE powder and the liquid lubricant to produce 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

   And firing the mixture in the step (7).
10. 9. The process for producing a fuel cell electrolyte-reinforced membrane according to claim 8, wherein the uniaxial stretching in the five-step stretching is performed in the longitudinal direction at a stretching temperature of 260 to 350 DEG C and a stretching speed of 6 to 12 M / Way.
11. The fuel cell electrolyte-reinforced membrane according to claim 8, wherein the biaxial stretching in the five-step stretching is performed in the transverse direction at a stretching temperature of 150 ° C to 260 ° C and a stretching speed of 10 to 20 M / Gt;
12. 10. The method of claim 9, wherein the fluorine ionomer solution comprises

    Spherical hollow silica having an average particle diameter of 10 nm to 300 nm; And

    Zeolite, titania, zirconia and montmorillonite; Wherein the fuel cell electrolyte-reinforced membrane further comprises at least one selected from the group consisting of hydrogen peroxide and hydrogen peroxide.
13. A membrane-electrode assembly comprising the fuel cell electrolyte-reinforced membrane of claim 1.
14. An electricity generating unit including the membrane-electrode assembly and the separator of claim 13, 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 >

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