KR100608482B1 - Proton exchange membrane comprising compatibilizer and fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a hydrogen ion conductive polymer membrane comprising a compatibilizer and a fuel cell including the same. More specifically, in the polymer electrolyte membrane, a polyethylene oxide (PEO), a polypropylene oxide (PPO) as a compatibilizer (compatibilizer) Or to a hydrogen ion conductive polymer membrane comprising a compatibilizer characterized in that it comprises a copolymer thereof and a fuel cell comprising the same.

The polymer electrolyte membrane of the present invention includes a Pluronic or Tetronic polymer having a hydrophilic group and a hydrophobic group as a compatibilizer, so that the hydrophilic and hydrophobic inorganic fillers can be uniformly dispersed in the polymer membrane, and the hydrophilic group in the polymer electrolyte membrane It lowers the moisture content, lowers the swelling degree of the electrolyte membrane against moisture and increases the dimensional stability when applying membrane-electrode assembly (MEA), and enables stable fuel cell operation. It improves the hydrogen ion conductivity by improving the content of UNDER WATER and BOUND WATER, and at the same time, the barrier property to methanol is secured by introducing compatibilizer and compatibilizer-inorganic filler to the membrane to improve methanol permeability. Chemistry such as thermal stability, hydration stability, free radical stability To improve the mechanical properties such as tensile strength and physical properties.

Fuel Cell, Polymer Electrolyte Membrane, Compatibilizer, Filler

Description

Hydrogen-conducting polymer membrane containing a compatibilizer and a fuel cell comprising the same {PROTON EXCHANGE MEMBRANE COMPRISING COMPATIBILIZER AND FUEL CELL COMPRISING THE SAME}

1 shows a schematic assembly of a fuel cell that generates water simultaneously with the generation of electrical energy.

<Explanation of symbols for the main parts of the drawings>

1: Hydrogen conductive solid polyelectrolyte 2: Hydrogen or methanol solution

3: air or oxygen 4: anode of fuel cell

5: cathode of fuel cell 6: external circuit

7: generation of water 8: coating layer

9: migration of hydrogen ions

[Industrial use]

The polymer electrolyte membrane of the present invention includes a Pluronic or Tetronic polymer or oligomer having a hydrophilic group and a hydrophobic group as a compatibilizer, so that the hydrophilic and hydrophobic inorganic fillers can be uniformly dispersed in the polymer membrane, and the hydrophilic group in the polymer electrolyte membrane It lowers the moisture content of the surroundings, reduces the swelling degree of the electrolyte membrane against moisture and increases the dimensional stability when applying the membrane-electrode assembly (MEA), and enables stable fuel cell operation. It improves the content of (bound water, BOUND WATER) and contributes to the improvement of hydrogen ion conductivity.At the same time, it introduces a compatibilizer and a compatibilizer-inorganic filler to the membrane to secure barrier properties to methanol. Reduces permeability, thermal stability, hydration stability, free radical The mechanical properties such as tensile strength and chemical properties such as the property relates to a proton-conducting polymer membrane and a fuel cell including the same, including an improved compatibilizer.

[Prior art]

Solid polymer electrolyte fuel cells have been proposed and developed in the 1950s for the purpose of supplying energy to spacecraft. The interest in fuel cells continues to evolve in addition to the power supply for spacecraft, and the automotive industry is attracting much attention for two reasons. First, interest in preventing air pollution by combustion of internal combustion engines is amplified. In practice, it is very difficult to completely block all emission compounds such as nitrogen oxides, incompletely burned hydrocarbons and acidic compounds by combustion of internal combustion engines through the control of internal combustion engines' own combustion reactions. Second, developing cars that use fuels other than fossil fuels, such as oil and coal, that are not permanent in the long run.

The polymer electrolyte fuel cell includes a hydrogen exchange gas fuel cell (Proton Exchange Membrane Fuel Cell (PEMFC)) and a direct methanol fuel cell using liquid methanol directly supplied to the anode. Fuel Cell: DMFC). The fuels supplied, hydrogen and methanol, are almost permanent and produce only water as a by-product through electrochemical reactions.

A schematic assembly of a fuel cell that generates water simultaneously with the generation of electrical energy is shown in FIG. 1.

Referring to FIG. 1, the ion exchange membrane 1 made of a solid polymer electrolyte has an anode in which hydrogen or methanol solution 2 uses air or oxygen 3 as fuel, and oxidation of fuel occurs as shown in the following reaction formula ( anode part (4) and

For hydrogen fuel cells:

2H ₂ → 4H ^{+ +} 4e ^-

For direct methanol fuel cells:

_{CH 3 OH + H 2 O →} CO 2 + 6H + + 6e -

When the anode and the cathode are connected through an external circuit 6 as shown in the following scheme, it is used to isolate the cathode portion 5 in which an oxidant such as oxygen is reduced together with the production of water 7.

For hydrogen fuel cells:

_{^{O 2 + 4H + + 4e -}} → 2H 2 O

For direct methanol fuel cells:

^{_{3 / 2O 2 + 6H + +}} 6e - → CO 2 + 2H 2 O

The anode and cathode are basically composed of a carbon-based hydrogen ion conductive support on which metal particles such as platinum and ruthenium are deposited. In order to improve the adhesion between the positive and negative electrodes and the polymer electrolyte membrane, and to improve the conductivity of hydrogen ions generated by the formation of an appropriate three-phase interface, the coating layer 8 mainly using a Nafion membrane was further formed into a thin film of 1 to 10 mg / cm ² . Become.

The membrane electrode assembly (MEA) has a very thin thickness in millimeters and each electrode is supplied with gases from behind the plate using a slotted plate.

Since 1950, numerous types of sulfonated polymers and polymer compositions have been tested for fuel cell membranes, and the relationship between chemical structure, film morphology and performance can be established to the present level. However, since the sulfonated polymer exhibits hydrogen ion transfer ability in the hydrated state, a drastic decrease in hydrogen ion conductivity occurs due to a decrease in moisture in the polymer film and decomposition of sulfonic acid groups at a high temperature when operating at a high temperature of 90 ° C. or higher. Therefore, several methods have been studied to solve the problem of reducing the hydrogen ion conductivity during high temperature operation.

For example, in the conventional commercialized perfluorinated sulfonated ionomers such as Nafion of Du Pont, USA, TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , tetraethoxysilane (TEOS), montmorillonite Inorganic oxides such as montmorillonite and mordenite have been introduced to improve the water-carrying capacity at high temperatures, thereby largely eliminating the decrease in hydrogen ion conductivity at high temperatures above 100 ° C. In addition, the decrease in the water support at high temperatures and the reduction in the hydrogen ion conductivity thereof, such as zirconium phosphoric acid (ZrP), phosphotungstic acid, silicotungstic acid, phospho molybdate acid, silico molybdate acid, etc. It was offset by introducing heteropolyacid (HPA). However, the introduction of such an inorganic oxide has a limit of the amount of introduction according to the physical properties including the physical strength of the film produced.

      In addition, in order to eliminate the effect of moisture content with temperature directly affecting the hydrogen ion conductivity of the perfluorinated polymer electrolyte, there have been attempts to substitute inorganic acids such as phosphoric acid instead of water as a medium for hydrogen ion transfer.

In addition to the fluorine-based polymer electrolyte research for fuel cells, research on non-fluorine sulfonated ionomers has also been actively conducted. In general, a form in which sulfonic acid groups for imparting hydrogen ion conductivity to heat-resistant polymers such as polysulfones, polyethersulfones, polyetherketones, polyimides and polyphosphazenes has been studied. Although the decrease was small compared to the sub-sulfated ionomer, a similar decrease in hydrogen ion conductivity was observed. Therefore, the introduction of an inorganic oxide to the sulfonated heat-resistant polymer to solve the problem of reducing the hydrogen ion conductivity by improving the water support at high temperature, or to reduce the moisture content at high temperature by introducing heteropolyacid (HPA) having high hydrogen ion conductivity. Attempts have been made to compensate or eliminate the reduction in hydrogen ion conductivity. However, in the case of introducing the inorganic oxide, there is a problem in the introduction amount limit, and in the case of the introduction of HPA, the introduced HPA is leaking out from the polymer matrix (Leaching out) occurred.

       In particular, when the inorganic filler is introduced, a hybrid membrane or a composite membrane is manufactured by introducing a predetermined amount of inorganic filler precursor to grow the inorganic filler by the sol-gel method or by directly dispersing the inorganic filler into the polymer matrix. do. The former method can be used to prepare composite membranes containing porous silica by the sol-gel method through the introduction of silica precursors such as TEOS as in Journal of membrane science 2002, 109, 356-364, or the Journal of membrane science 2004, 237, 145-. As described in 161, a method of preparing a composite membrane in which a poorly soluble zirconium phosphate is introduced by supporting a polymer matrix in a zirconium chloride precursor solution, and the latter is a case of the Journal of membrane science 2004, 229, As in the method of 43-51, the inorganic filler powder is directly introduced into the polymer solution, and then ultrasonic waves are applied for a predetermined time to prepare a composite membrane through relatively uniform inorganic filler dispersion, or the Journal of membrane science 2000, 173, 17-34 and Likewise, a certain amount of HPA-based inorganic filler powder is introduced into the prepared polymer solution, followed by stirring for a long time, or through stirring with heating. To prepare composite membranes. Most of the above methods have been used to counteract the reduction in the conductivity of hydrogen ion at high temperatures through the introduction of inorganic fillers or to improve the mechanical properties of the polymer matrix. However, in most cases where the inorganic filler powder is directly introduced, the uniform dispersion of the inorganic filler is not achieved, and thus, even film properties are not frequently obtained. As a result, despite the introduction of a relatively small amount of inorganic fillers, the breakage of the polymer membrane is increased to weaken the mechanical properties, or to have a high reliability of the basic performance of the polymer electrolyte membrane such as hydrogen ion conductivity, thermal stability, and hydration stability. do. In addition, in DMFC applications, a uniform barrier against methanol is not obtained.

       An object of the present invention includes a Pluronic or Tetronic polymer or oligomer having a hydrophilic group and a hydrophobic group as a compatibilizer, so that the hydrophilic and hydrophobic inorganic fillers can be uniformly dispersed in the polymer membrane, the hydrophilic group around the polymer electrolyte membrane It lowers the moisture content of the membrane, lowers the swelling degree of the electrolyte membrane against moisture and increases the dimensional stability when applying the membrane-electrode assembly (MEA), and enables stable fuel cell operation. It improves the hydrogen ion conductivity by improving the content of bounder water (BOUND WATER), and at the same time, the barrier property to methanol is ensured by introducing compatibilizer and compatibilizer-inorganic filler to the membrane to ensure methanol permeability. And thermal stability, hydration stability, free radical stability, etc. Chemical properties and to provide a proton-conducting polymer membrane comprising a first commercialized having improved mechanical properties such as tensile strength.

It is also an object of the present invention to provide a fuel cell comprising a hydrogen ion conductive polymer membrane comprising the compatibilizer.

In order to achieve the above object, the present invention is a polymer electrolyte membrane,

Provided is a hydrogen ion conductive polymer membrane comprising a compatibilizer, characterized in that it comprises polyethylene oxide (PEO), polypropylene oxide (PPO) or a copolymer thereof as a compatibilizer.

The present invention also provides a fuel cell having a hydrogen ion conductive polymer membrane comprising the compatibilizer.

Hereinafter, the present invention will be described in more detail.

The inventors of the present invention added an inorganic filler in a polymer membrane prepared by adding a polyethylene oxide (PEO), a polypropylene oxide (PPO) or a copolymer thereof having a hydrophilic group or a hydrophobic group as a compatibilizer in preparing a polymer membrane. It can reduce the water content around the hydrophilic group in the polymer electrolyte membrane, reduce the swelling degree of the electrolyte membrane against water and increase the dimensional stability when applying the membrane-electrode assembly (MEA), and enable stable fuel cell operation. By improving the content of water (bound water, BOUND WATER) having a strong interaction with the reactive group, it contributes to the improvement of the hydrogen ion conductivity, and at the same time the barrier to methanol through the introduction of a compatibilizer and a compatibilizer-inorganic filler to the membrane It reduces the permeability of methanol by securing the BARRIER property, and the thermal stability, In view of the fact that the stability, the mechanical properties such as tensile strength and chemical properties, such as free radical stability is improved and completed the present invention.

The hydrogen ion conductive polymer membrane of the present invention is characterized in that it comprises polyethylene oxide (PEO), polypropylene oxide (PPO) or a copolymer thereof as a compatibilizer.

As the polymer membrane material, materials of a polymer membrane which are generally widely used are possible, and particularly preferred examples thereof include polyimide, polysulfone, polyarylene ether sulfone, polyarylene ether ketone, polybenzimidazole, polybenzoxazole, Polybenzozazole, polyether ether ketone, polyphosphazene and the like. Moreover, it is more preferable that such a polymer film contains hydrophilic functional groups, such as a sulfonic acid group, a carbonic acid group, and a phosphoric acid group.

Particularly, in the present invention, the compatibilizer is preferably a polymer or oligomer having a hydrophilic group such as polyethylene oxide (PEO) or a hydrophobic group such as polypropylene oxide (PPO), and a pluronic or tetronic polymer and oligomer having both hydrophilic and hydrophobic groups. More preferred are compatibilizers in the form of terpolymers of the same PEO and PPO.

As a compatibilizer in the preparation of a polymer film, a polymer or oligomer having a hydrophilic group such as polyethylene oxide (PEO) or a hydrophobic group such as polypropylene oxide (PPO) and a pluronic or tetronic polymer or oligomer having both a hydrophilic group and a hydrophobic group In the case of adding the same terpolymer form of PEO and PPO, the effect is summarized as follows.

1. Improving dispersibility of inorganic filler including silica and the like.

Pluronic (trade name Poloxamer) is a terpolymer composed of PEO-PPO-PEO. PEO units in the compatibilizers are hydrophilic and PPO units are hydrophobic. For example, when the hydrophilic fumed silica is introduced in the preparation of the polymer membrane, when the hydrophobic silica and the interaction through hydrogen bonding between the PEO repeat unit-hydrophilic fumed silica in the hydrophilic region-compatible agent of the polymer are introduced, The interaction between PPO-hydrophobic fumed silica in the hydrophilic region-compatibility of the polymer results in uniform dispersion of fumed silica.

[Formula 1]

       2. Reduced moisture content in the polymer membrane.

Since the interaction between the polymer-compatibility-silica described above prevents the access of many water molecules around the sulfonic acid group, the water content is reduced. This is because, when manufacturing a unit cell using a polymer membrane, the MEA bonding performance is rapidly decreased due to the large difference in swelling degree due to water absorption, and the battery performance is also reduced. Therefore, a low water content should be directed for manufacturing a high performance battery.

3. Improved bound water content in composite membrane.

Unlike the decrease in water content, depending on the interaction between the water molecule and the hydrophilic group in the polymer / hydrophilic group in the compatibilizer / hydrophilic fumed silica surface, the bound water content, which is a water molecule having a strong interaction force with the reactive group, is relatively Increase (43-87%).

4. Improved hydrogen ion conductivity of polymer membrane.

Increasing the bound water content has two effects on the hydrogen ion conductivity. 1) improvement of hydrogen ion conductivity at the same temperature and 2) continuous improvement of hydrogen ion conductivity with temperature rise. In addition, even in the case of the composite membrane containing only the compatibilizer, the hydrogen ion conductivity according to the hydrophilic group content of the compatibilizer is increased.

5. Reduced methanol permeability of polymer membrane.

In the case of a composite membrane in which only a compatibilizer is introduced or a homogeneous dispersion of silica is induced using a compatibilizer, methanol permeability is reduced because barrier property to methanol is induced.

6. Improved mechanical properties of polymer membranes.

In the case of the composite membrane in which the compatibilizer and the compatibilizer-silica are introduced, the mechanical properties such as tensile strength are substantially improved compared to the mechanical properties of the polymer membrane alone.

7. Improved thermal, hydration and free radical stability of polymer membrane.

In the case of the organic-inorganic composite membrane containing silica, the thermal stability of the membrane is improved. In addition, the greatest advantage of the polyimide-silica composite membrane is the improvement in hydration stability due to the uniform dispersion of silica. The hydration stability of the polyimide membrane alone has a stability of about 70 hours in ultrapure water at 80 ° C., but when silica and a compatibilizer are included, the hydration stability can be secured for 5,000 hours or more due to the formation of a more dense polymer structure. . In addition, the stability of radical peroxide using ferrous ammonium salt + H ₂ O ₂ solution (Fenton's reagent) is also significantly improved.

The content of the compatibilizer in the present invention described above is preferably 0.1 to 40 parts by weight based on 100 parts by weight of the polymer film to be prepared, and the content of the compatibilizer is less than 0.1 part by weight based on 100 parts by weight of the polymer film. It is not preferable because it hardly appears, and in addition, when the content of the compatibilizer exceeds 40 parts by weight with respect to 100 parts by weight of the polymer film, various properties such as hydrogen ion conductivity and tensile strength of the polymer film are proportional to the content of the compatibilizer added. It is not economical simply because it does not increase.

Although the polymer membrane including the compatibilizer of the present invention described above can be used in a polymer membrane without an inorganic filler, TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , tetraethoxysilane (TEOS), montmorillonite various inorganic fillers such as inorganic oxides such as montmorillonite, mordenite, or heteropolyacids such as zirconium phosphate (ZrP), phosphotungstic acid, silicotungstic acid, phospho molybdate, silico molybdate, etc. More preferably, the compatibilizers described above are added when preparing the composite membrane added to the membrane in the form. Various methods of adding a compatibilizer may be possible, but a method of adding a compatibilizer together with an inorganic filler is preferable.

In addition, the polymer membrane of the present invention can be used in various applications such as fuel cell, electrolysis, aqueous and non-aqueous electrodialysis and diffusion dialysis, pervaporation, gas separation, dialysis, ultrafiltration, nanofiltration or reverse osmosis process. , Particularly for fuel cells.

As described above, the hydrogen ion conductive polymer membrane of the present invention includes a flupuronic or tetronic polymer having a hydrophilic group and a hydrophobic group as a compatibilizer, so that hydrophilic and hydrophobic inorganic fillers can be uniformly dispersed in the polymer membrane, It lowers the water content around the hydrophilic group in the polymer electrolyte membrane, reduces the swelling degree of the electrolyte membrane against water and increases the dimensional stability when applying the membrane-electrode assembly (MEA), and enables stable fuel cell operation. It improves the hydrogen ion conductivity by improving the content of water (bound water, BOUND WATER) which has an interaction force, and at the same time, barrier to methanol through the introduction of a compatibilizer and a compatibilizer-inorganic filler for the membrane. To reduce the permeability of methanol, to ensure the thermal properties of the polymer membrane, the stability of hydration It improves the chemical properties such as stability, free radical stability, and mechanical properties such as tensile strength.

Hereinafter, preferred examples and comparative examples of the present invention are described. The following examples and comparative examples are described for the purpose of more clearly expressing the present invention, but the contents of the present invention are not limited to the following examples and comparative examples.

(Example 1)

The condensation reaction of the polyimide was carried out in a 250 ml reactor equipped with a teflon stirrer and an inlet for inert gas such as nitrogen and a sample inlet. The reactor was installed in an oil-filled thermostat to maintain a constant reaction temperature.

0.86 g (2.4 mmol) of 4,4'-diamino diphenyl ether-2,2'-disulfonic acid (ODADS) was added to the reactor, and m-cresol was added as a solvent. As reaction catalyst, 0.96 g (9.6 mmol) of triethylamine and 0.68 g (5.68 mmol) of benzoic acid were added. 1,4,5,8-naphthalene tetracarboxylic anhydride (NTDA) powder 1.07g (4mmol) was slowly injected into the completely dissolved solution, completely dissolved and reacted for 1 hour, and then 3,5-diamino After adding 0.23 g (1.6 mmol) of benzoic acid (DBA) powder, the mixture was reacted for about 1 hour.

Subsequently, the temperature was raised to 80 ° C., followed by 4 hours of reaction, and the temperature was raised to 180 ° C. for 20 hours to prepare a polyimide having a dark brown viscosity in solution. The prepared polyimide was deposited in acetone solution to remove unreacted monomers and oligomers to give 2.3 g of sulfonated polyimide powder. The obtained powder was again dissolved in 9.2 g of m-cresol, and slowly injected a solution containing 0.023 g of silica (Aerosil 200, hydrophilic silica) and 0.03 g of Floronic ^® (Polaxomer 1100, L31) with a compatibilizer at a temperature of 150 ° C. After the reaction, the reaction was carried out for 8 hours.

After casting the solution on a glass plate, the thermosetting and imidization was completed for 10 hours in a vacuum oven at 180 ° C., and vacuum-dried for 24 hours in a vacuum oven at 110 ° C. in order to completely remove residual solvent. An opaque sulfonated polyimide membrane with a brown color was prepared. The ion exchange capacity (IEC) of the membrane was 1.80 meq / g.

(Example 2)

A sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Polaxomer 1900 (L35) was used as a compatibilizer.

(Example 3)

A sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Polaxomer 2900 (L64) was used as a compatibilizer.

(Example 4)

A sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Polaxomer 3500 (L92) was used as a compatibilizer.

(Example 5)

A sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Aerosil 812 (hydrophobic silica) was used as silica.

(Example 6)

Polaxomer 1900 (L35) was used as a compatibilizer, and sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Aerosil 812 was used as silica.

(Example 7)

Polaxomer 2900 (L64) was used as a compatibilizer, and sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Aerosil 812 was used as silica.

(Example 8)

Polaxomer 3500 (L92) was used as a compatibilizer, and sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Aerosil 812 was used as silica.

(Example 9)

Polaxomer 2900 (L64) was used as a compatibilizer, and the sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that silica was not added.

(Comparative Example 1)

A sulfonated polyimide membrane was prepared in the same manner as in Example 1 except that Floronic ^® and an inorganic additive were not introduced as the compatibilizer.

Experimental Example

For the sulfonated polyimide membranes prepared in Examples 1 to 9 and Comparative Example 1, hydrogen ion conductivity according to temperature (Table 1), hydrogen ion conductivity according to relative humidity (Table 2), water content (Table 3), bound The water content (Table 4), methanol permeability (Table 5), selectivity (Tableivity 6) and hydration stability (Table 7) were measured and shown in Tables 1-7 below.

Hydrogen ion conductivity is obtained by measuring ohmic resistance or bulk resistance using the Four Point probe AC impedance spectroscopic method and substituting it into the equation σ = l / (RXS). Where σ (S / cm) is the hydrogen ion conductivity, l (cm) is the distance between the voltage drop electrodes, R (Ω) is the ohmic resistance of the polymer electrolyte, and S is the area in the electrolyte through which a constant current passes (cm ² ) Means. Quadrupole electrode structure for measuring hydrogen ion conductivity can control constant temperature and constant humidity connected with electrochemical interface (Solatron 1287, Solatron Analytical, Farnborough Hampshire, GU14, ONR, UK) and impedance phase analyzer (Solatron 1260) It is installed in a constant temperature and humidity chamber, and the ohmic resistance is measured using Nyquist diagram and Bode diagram. As a principle of measurement, when a constant current (10mA) is applied to two electrodes outside the quadrupole electrode through the polymer electrolyte, the resistance is measured by measuring the voltage drop between the inner two electrodes. Table 1 is a value measured while heating at a constant humidity of 95% RH using the measuring device and measuring method, Table 2 is a value measured while humidifying at a constant temperature 60 ℃ using the same measuring device and measuring method.

[Table 1] Hydrogen ion conductivity according to temperature (S / cm)

division Temperature (℃) 30 45 60 75 90 Example 1 6.04X10 ^-2 6.08X10 ^-2 7.12 X 10 ^-2 7.15 X 10 ^-2 7.64X10 ^-2 Example 2 7.67 X 10 ^-2 7.70X10 ^-2 7.74 X 10 ^-2 7.83 X 10 ^-2 8.17X10 ^-2 Example 3 8.55X10 ^-2 8.78X10 ^-2 9.00X10 ^-2 9.22X10 ^-2 7.88X10 ^-2 Example 4 8.98X10 ^-2 9.24X10 ^-2 9.46 X 10 ^-2 9.73 X 10 ^-2 9.33X10 ^-2 Example 5 6.25X10 ^-2 6.28X10 ^-2 6.31X10 ^-2 7.40X10 ^-2 9.83X10 ^-2 Example 6 6.60X10 ^-2 6.63X10 ^-2 6.70X10 ^-2 7.75 X 10 ^-2 8.41X10 ^-2 Example 7 6.30X10 ^-2 6.40X10 ^-2 6.48X10 ^-2 7.56 X 10 ^-2 8.80X10 ^-2 Example 8 6.03X10 ^-2 6.40X10 ^-2 6.27X10 ^-2 7.41 X 10 ^-2 8.65X10 ^-2 Example 9 7.32X10 ^-2 6.15X10 ^-2 7.85X10 ^-2 8.08X10 ^-2 8.58X10 ^-2 Comparative Example 1 5.23X10 ^-2 5.80X10 ^-2 6.19X10 ^-2 6.90X10 ^-2 7.33 X 10 ^-2

As shown in Table 1, when the membrane is prepared by adding Pluronic (Polaxomer), a terpolymer of PEO and PPO as a compatibilizer, a strong interaction force with the reactive group in the polymer membrane compared to the membrane prepared without the addition of the compatibilizer As the bound water content increased, the hydrogen ion conductivity and the hydrogen ion conductivity of the same measured temperature were improved.

 [Table 2] Hydrogen ion conductivity according to relative humidity (S / cm)

division Relative Humidity (%) 75 82 90 98 Example 1 4.46X10 ^-2 5.18X10 ^-2 5.99X10 ^-2 6.44X10 ^-2 Example 2 5.45X10 ^-2 6.45X10 ^-2 7.68X10 ^-2 7.78 X 10 ^-2 Example 3 5.96X10 ^-2 6.92X10 ^-2 8.68X10 ^-2 9.03X10 ^-2 Example 4 6.45X10 ^-2 7.65X10 ^-2 9.25X10 ^-2 9.48X10 ^-2 Example 5 4.32X10 ^-2 5.03X10 ^-2 5.98X10 ^-2 6.34X10 ^-2 Example 6 4.21X10 ^-2 4.91X10 ^-2 5.97X10 ^-2 6.29X10 ^-2 Example 7 4.12X10 ^-2 4.83X10 ^-2 5.95X10 ^-2 6.25X10 ^-2 Example 8 4.04X10 ^-2 4.75X10 ^-2 5.92X10 ^-2 6.23X10 ^-2 Example 9 3.85X10 ^-2 4.62X10 ^-2 5.95X10 ^-2 6.40X10 ^-2 Comparative Example 1 3.80X10 ^-2 4.53X10 ^-2 5.89X10 ^-2 6.20X10 ^-2

In addition, as shown in Table 2, in the case of a membrane prepared by adding Pluronic terpolymer of PEO and PPO as a compatibilizer, hydrogen ion conductivity at a constant humidity and relative humidity increase compared to the membrane prepared without the compatibilizer It was found to be improved.

[Table 3] Water content (%)

division Weight of membrane before swelling Weight of membrane after swelling Moisture content (%) Example 1 1.6329 2.1881 34.0 Example 2 1.3937 1.8578 33.3 Example 3 1.0906 1.4320 31.3 Example 4 1.2386 1.6077 29.8 Example 5 1.7729 2.2587 27.4 Example 6 1.5286 1.9597 28.2 Example 7 2.2881 2.9631 29.5 Example 8 1.6872 2.2254 31.9 Example 9 1.2883 1.7186 33.4 Comparative Example 1 1.3456 1.8058 34.2

In addition, Table 3 shows the results of the measurement of moisture content, which was measured by swelling the prepared membrane in ultrapure water at 25 ° C. for one day (weight of membrane after swelling-weight of membrane before swelling) / (weight of membrane before swelling) × 100. As shown in Table 3 above, it was found that the swelling degree of the sulfonated polyimide membrane prepared by adding the compatibilizer and the inorganic oxide was also low in water content, so that relatively high dimensional stability was obtained.

Table 4 Bound Water Content (%)

division Free water Bound water Example 1 56.8 43.2 Example 2 39.4 60.6 Example 3 20.7 79.3 Example 4 12.2 87.8 Example 5 20.6 79.4 Example 6 26.5 73.5 Example 7 30.9 69.1 Example 8 36.9 63.1 Example 9 62.2 37.8 Comparative Example 1 67.2 32.8

The content of bound water having a strong interaction with the reactive group in the polymer was determined by using the heat of fusion of water obtained as a result of DSC measurement by heating at a constant rate (5 ° C./min) at -50 to 50 ° C. and the moisture content measured in Table 3 above. (Heat of fusion of endothermic peak at temperature of measurement range) / (heat of fusion of ultrapure water, 344 J / g)

As shown in Table 4, the sulfonated polyimide membrane prepared by adding a compatibilizer even in the bound water content is relatively higher than the case where no compatibilizer is added. It was found that the hydrogen ion conductivity was improved.

Table 5 Methanol Permeability

division Methanol Permeability (cm ² / s) Example 1 3.37X10 ^-6 Example 2 2.37X10 ^-7 Example 3 1.48X10 ^-7 Example 4 1.09X10 ^-7 Example 5 2.06X10 ^-7 Example 6 1.24X10 ^-7 Example 7 1.04X10 ^-7 Example 8 9.89X10 ^-8 Example 9 4.22X10 ^-7 Comparative Example 1 1.06X10 ^-6

Methanol permeability was measured by the two chamber diffusion cell method. Before measurement, the polymer electrolyte membrane is swollen for one day or more in ultrapure water, and is installed between both chambers. When one chamber is filled with 10 M methanol solution, the other chamber is filled with ultrapure water, and after time, methanol diffuses from the chamber filled with methanol solution to the chamber filled with ultrapure water through the polyelectrolyte. The amount of methanol diffused could be measured using gas chromatography (GC, Shimadtzu, GC-14B, Tokyo, Japan).

As shown in Table 5, in the case of the sulfonated polyimide membrane prepared by adding a compatibilizer, it was found that methanol permeability was reduced by more than 10 times because the barrier property to methanol was induced.

[Table 6] Selectivity

division Selectivity (Ssec / cm ³ ) Example 1 1.83 X 10 ⁵ Example 2 3.32X10 ⁵ Example 3 6.30X10 ⁵ Example 4 9.02X10 ⁵ Example 5 2.63X10 ⁵ Example 6 3.87X10 ⁵ Example 7 4.47 X 10 ⁵ Example 8 4.63X10 ⁵ Example 9 1.97X10 ⁵ Comparative Example 1 7.21 X 10 ⁴

When the polymer membrane of the present invention is applied to a direct methanol fuel cell (DMFC), it should preferably exhibit high hydrogen ion conductivity and low methanol permeability. Thus, the term selectivity is used to indicate the performance of the polymer electrolyte. Here, selectivity means hydrogen ion conductivity / methanol permeability.

As shown in Table 6, in the case of the sulfonated polyimide membrane prepared by the addition of a compatibilizer it was found that the selectivity was improved up to 10 times or more.

[Table 7] Sign Language Stability

division Hour (hr) Example 1 More than 5,000 Example 2 More than 5,000 Example 3 More than 5,000 Example 4 More than 5,000 Example 5 More than 5,000 Example 6 More than 5,000 Example 7 More than 5,000 Example 8 More than 5,000 Example 9 More than 5,000 Comparative Example 1 70 hours

Hydration stability is a property that must be met in the case of a humidified electrolyte in which hydrogen ions are transferred through water. That is, in the case of a humidified electrolyte, since it usually contains acidic groups, such as a sulfonic acid group, a carbonate group, and a phosphate group, decomposition | disassembly of a polymer in a hydration state is accelerated | stimulated. Therefore, the stability in the hydrated state is directly related to the reliability of the fundamental performance of the fuel cell application of the prepared polymer electrolyte. The measurement of hydration stability can be made through various methods, but the hydration stability in the present invention is measured by aging the polymer electrolyte in ultrapure water at 80 ° C. for a predetermined time, and then hydrogen was first measured under certain conditions (95% RH, 80 ° C.). Hydration stability was evaluated by measuring the time when the change was more than 5% compared to the ion conductivity.

       As shown in Table 7, in the case of the sulfonated polyimide membrane which does not include a compatibilizer, a problem of low hydration stability, which is a fundamental problem in fuel cell application of most sulfonated polyimide membranes, is observed. In the case of the composite membrane including the inorganic filler, it was found that the problem of hydration stability of the sulfonated polyimide membrane could be fundamentally solved.

As described above, the polymer electrolyte membrane in the present invention includes a pluronic or poloxamer-based polymer or oligomer having a hydrophilic group and a hydrophobic group as a compatibilizer, so that the hydrophilic and hydrophobic inorganic fillers can be uniformly dispersed in the polymer membrane. In addition, it lowers the water content around the hydrophilic group in the polymer electrolyte membrane, and reduces the swelling degree of the electrolyte membrane against water and increases the dimensional stability when applying the membrane-electrode assembly (MEA), and enables stable fuel cell operation. Improves the content of water (bound water, BOUND WATER) with a strong interaction force, contributes to the enhancement of hydrogen ion conductivity, and at the same time barriers to methanol through the introduction of a compatibilizer and a compatibilizer-inorganic filler for the membrane (BARRIER) To reduce the permeability of methanol and to ensure the thermal stability of the polymer membrane Chemical properties such as hydration stability and free radical stability and mechanical properties such as tensile strength can be improved.

Claims (7)

In the polymer electrolyte membrane, A hydrogen ion conductive polymer membrane comprising a compatibilizer, characterized in that it comprises polyethylene oxide (PEO), polypropylene oxide (PPO) or copolymer polymers and oligomers thereof as a compatibilizer. The method of claim 1, Compatibilizer (compatibilizer) is a hydrogen ion conductive polymer membrane comprising a compatibilizer, characterized in that the Pluronic (Pluronic) or Tetronic (tetronic) terpolymer of PEO-PPO-PEO. The method of claim 1, The addition amount of the compatibilizer is a hydrogen ion conductive polymer membrane comprising a compatibilizer, characterized in that 0.1 to 40 parts by weight based on 100 parts by weight of the polymer film. The method of claim 1, The polymer membrane is a hydrogen ion conductive polymer membrane comprising a compatibilizer, characterized in that the polymer electrolyte membrane for fuel cells. The method of claim 1, The polymer film is TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , tetraethoxysilane (TEOS), montmorillonite, mondenite, mordenite, zirconium phosphate (ZrP), phosphotungstic acid, A hydrogen ion conductive polymer membrane comprising a compatibilizer further comprising an inorganic filler selected from the group consisting of silicotungstic acid, phospho molybdate and silico molybdate. The method of claim 1, The material of the polymer membrane is polyimide, polysulfone, polyarylene ether sulfone, polyarylene ether ketone, polybenzimidazole, polybenzoxazole, polybenzisazole, polypyrrolone, polyether ether ketone and polyphosphazene A hydrogen ion conductive polymer membrane comprising a compatibilizer, characterized in that selected from the group consisting of. A fuel cell provided with a hydrogen ion conductive polymer membrane comprising the compatibilizer according to any one of claims 1 to 6.

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