KR100701473B1 - Proton conductive composite membrane comprising surfactant and inorganic filler, and fuel cell comprising the same - Google Patents

Abstract

Provided are a hydrogen ion conductive polymer composite membrane which is excellent in the dispersion of an inorganic filler and is increased in dimension stability, a membrane electrode assembly containing the composite membrane, and a fuel cell containing the composite membrane. The hydrogen ion conductive polymer composite membrane comprises 0.01-40 wt% of a surfactant which comprises polyethylene oxide, polypropylene oxide or their copolymer polymer and oligomer, helps dispersion of an inorganic material and forms a crosslinked, IPN and graft structure; and 0.01-40 wt% of an inorganic filler which comprises an inorganic oxide, a heteropolyacid or their mixture. Preferably, the surfactant is a terpolymer comprising polyethylene oxide as a hydrophilic moiety and polypropylene oxide as a hydrophobic moiety.

Description

Hydrogen-conducting polymer composite membrane comprising a surfactant and an inorganic filler, and a fuel cell comprising the same {PROTON CONDUCTIVE COMPOSITE MEMBRANE COMPRISING SURFACTANT AND INORGANIC FILLER, 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]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen ion conductive polymer composite membrane comprising a crosslinking agent, an IPN, a surfactant for forming a graft structure, and an inorganic filler having various functionalities, and a fuel cell including the same. Is a polymer composite membrane, characterized in that it comprises polyethylene oxide (PEO), polypropylene oxide (PPO) or a copolymer thereof as a surfactant, and silica (SiO ₂ ), alumina (Al ₂ O ₃ ) as an inorganic filler ), Inorganic oxides such as titanium oxide (TiO ₂ ), manganese oxide (MnO ₂ ), zirconium oxide (ZrO ₂ ), tetraethoxysilane (TEOS), montmorillonite, mordenite and zirconium One selected from heteropolyacids (HPA) such as phosphoric acid (ZrP), phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and silicomolybdic acid It relates to a hydrogen ion conductive polymer composite membrane comprising a phase and a fuel cell comprising the same.

The hydrogen ion conductive polymer composite membrane of the present invention includes a pluronic or tetronic polymer surfactant having a hydrophilic and a hydrogen group serving as a dispersant, inducing uniform dispersion of the inorganic filler in the polymer electrolyte membrane, and the surfactant According to the polymer matrix can form a unique microstructure, such as crosslinking, IPN, graft structure. In addition, depending on the action of the inorganic filler introduced with the surfactant, the moisture content around the hydrophilic group in the polymer membrane and the dimensional stability is increased. In particular, when the polymer electrolyte composite membrane according to the present invention is used in a direct methanol fuel cell, it may contribute to the reduction of methanol crossover which is directly related to the reduction of fuel cell performance through catalyst poisoning. Unlike the decrease in water content, it leads to an increase in the content of water (bound water, BOUND WATER), which has a strong interaction with the reactive group in the polymer membrane (inorganic oxide), or hydrogen ion according to the increase of the HPA content having hydrogen ion conductivity. Contribute to improved conductivity. In addition, the polymer composite membrane of the present invention relates to a hydrogen ion conductive polymer composite membrane exhibiting excellent hydration stability and free radical stability according to the introduced inorganic filler and a fuel cell including the same.

[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.

Such polymer electrolyte fuel cells include 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 positive electrode and the negative electrode are connected through an external circuit 6 as shown in the following scheme, it is used to isolate the negative electrode 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 is 0.2 to 10 mg / cm ^2. It is added to a thin film of.

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 were introduced to improve the water-carrying capacity at high temperatures, thereby significantly reducing the hydrogen ion conductivity at high temperatures of 100 ° C or higher. 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. Although 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, a perfluorine system has been studied. Although the decrease was small compared to the sulfonated ionomer, a similar decrease in hydrogen ion conductivity was observed. Therefore, introducing an inorganic oxide into the sulfonated heat-resistant polymer to solve the problem of reducing hydrogen ion conductivity by improving water support at high temperature, or by introducing a heteropolyacid (HPA) having high hydrogen ion conductivity at high temperature Attempts have been made to compensate or eliminate the decrease in hydrogen ion conductivity due to the decrease in moisture content. However, when the inorganic oxide is introduced, there is a problem of limiting the amount of introduction, and in the case of introducing HPA, the introduced HPA leaks out of the polymer matrix.

       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 comprising porous silica by 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, after introducing a certain amount of the HPA-based inorganic filler powder into the prepared polymer solution, the mixture is stirred 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 of directly introducing the inorganic filler powder, even if the uniform dispersion of the inorganic filler is not made is not often obtained even film properties. 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 have high reliability on the basic performance of the polymer electrolyte membrane such as hydrogen ion conductivity, thermal stability, and hydration stability. I can't. In addition, there is a problem that it is difficult to ensure uniform barrier property to methanol in DMFC application.

In addition, in the case of the hydrogen ion conductive membrane including the compatibilizer of the previously disclosed Korean Patent Application No. 10-2005-0049817, the focus was mainly on the compatibilizer function, but specificity such as crosslinking between the compatibilizer and the polymer matrix, IPN, graft, etc. There was a lack of awareness of the correlation between structure-membrane performance due to the formation of microstructures, and the improvement of polymer membrane performance was observed due to the addition of several inorganic materials, such as MnO ₂ , which were not mentioned in previous papers.

In addition, in the case of US Patent US 2005/0136308 A1, a hydrogen ion conductive membrane in which Al (III) and Mn (II) are introduced is prepared, or MnO is mainly focused on improving the durability of the hydrogen ion conductive membrane against attack of reactive hydrogen peroxides. _{Although it} was intended to contribute to the improvement of fuel cell performance by introducing the catalyst electrode including ₂ , hydrogen ion conductivity and methanol permeability due to securing uniform dispersibility and formation of micro structures such as crosslinking, IPN, and graft by introducing surfactants. The same overall improvement in membrane performance is not mentioned.

 An object of the present invention relates to a surfactant capable of forming various microstructures according to a polymer matrix, and a hydrogen ion conductive polymer composite membrane including various inorganic fillers in such a polymer structure. Specifically, the surfactant which helps dispersion of the inorganic material and forms a crosslinking, IPN, and graft structure includes a pluronic or tetronic polymer having hydrophilic and hydrogenic groups, and thus uniform dispersion of the inorganic filler in the polymer electrolyte membrane. The surfactant can form unique microstructures such as crosslinking, IPN, graft structure, etc., depending on the polymer matrix, and also, depending on the action of the inorganic filler introduced with the surfactant, The reduction and dimensional stability are increased, and in DMFC applications, it contributes to the reduction of methanol crossover, which is directly related to the reduction of fuel cell performance through catalyst poisoning, and, unlike water content reduction, has a strong interaction with reactive groups in the polymer membrane. Induces an increase in the content of water (bound water) (inorganic oxides), or hydrogen ions by themselves It contributes to the improvement of proton conductivity with increasing HPA content having a conductivity, and to provide a superior hydration stability and free radical stability exhibit the hydrogen-ion conductive polymer composite film and a fuel cell including the same according to the introduction of the inorganic filler.

In order to achieve the above object, the present invention (a) as a surfactant to help the dispersion of inorganic materials, crosslinking, IPN, graft structure, polyethylene oxide (PEO), polypropylene oxide (PPO) or a copolymer polymer thereof and Surfactants including oligomers; And (b) an inorganic oxide, heteropolyacid, or a mixed inorganic filler thereof.

The present invention also provides a membrane-electrode assembly (MEA) comprising the hydrogen ion conductive polymer composite membrane.

The present invention also provides a fuel cell having a hydrogen ion conductive polymer composite membrane comprising the surfactant and an inorganic filler.

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

Surfactants that aid in the dispersion of inorganic materials and form crosslinks, IPNs, and graft structures include Pluronic or Tetronic polymer surfactants with hydrophilic and hydrogenated groups, inducing uniform dispersion of inorganic fillers in the polymer electrolyte membrane. The surfactant can form unique microstructures such as crosslinking, IPN, graft structure, etc. according to the polymer matrix, and also decreases the water content and dimensions around the hydrophilic group in the polymer membrane depending on the action of the inorganic filler introduced with the surfactant. Increased stability is achieved, and in DMFC applications, water contributes to the reduction of methanol crossover, which is directly related to the reduction of fuel cell performance through catalytic poisoning, and, unlike the decrease in water content, has a strong interaction with reactive groups in the polymer membrane. (Bound water, BOUND WATER) to increase the content (inorganic oxide), or hydrogen by itself And at the same time it contributes to the improvement of proton conductivity with increasing HPA content with on-conductive, by focusing on the fact that has a superior hydration stability and free radical stability, according to the introduction of the inorganic filler, thus completing the present invention.

The hydrogen ion conductive polymer composite membrane of the present invention helps dispersing inorganic materials and forms various functionalities together with polyethylene oxide (PEO), polypropylene oxide (PPO) or copolymers thereof as a surfactant to form crosslinking, IPN, and graft structures. It is characterized by including inorganic fillers, and inorganic fillers such as HPA.

For example, examples of preferred surfactants of the present invention include -OH groups having hydrophilic and hydrophobic groups and reactive groups at the ends of the surfactant chain, as shown in the following formula (1), and -COOH or -SO in the polymer matrix _{When 3} H is included, it reacts to induce a crosslinked or graft structure consisting of covalent bonds such as carboxylic acid esters or sulfonic acid esters, thereby reducing water content, thereby reducing methanol permeability and increasing stability due to preventing leakage of introduced surfactants. In addition, due to the surface hydrophilicity of the hydrophilic group and the nano-dispersed inorganic filler included in the surfactant or contribute to the increase in hydration stability, the increase in the bound water and the increase in the hydrogen ion conductivity.

As the material of the polymer membrane, all polymer materials generally used may be used. Particularly preferred examples thereof include perfluorinated polymer, polyimide, polysulfone, polyarylene ether sulfone, polyarylene ether ketone, polybenzimidazole, and polybenz. Oxazole, polybenzisazole, polyether ether ketone, polyphosphazene and the like. Moreover, it is 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 surfactant 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 surfactants in the form of terpolymers of PEO and PPO. In addition, inorganic fillers having various functionalities are introduced together with the surfactant according to the purpose of use.

The introduced surfactants lead to the formation of characteristic microstructures such as crosslinking, IPN and graft depending on the polymer matrix, and in the case of inorganic fillers introduced with these surfactants, the dispersibility is improved and thus dispersed in nano units. The polymer composite membrane can be obtained. The effects that can be observed are summarized as follows.

1. Reduced moisture content, increased dimensional stability, and reduced methanol permeability in the polymer membrane

In the case of the polymer membrane, in addition to the high interaction through the hydrogen bond between the hydrophilic PEO repeat unit of the hydrophilic region-surfactant of the polymer-hydrophilic inorganic filler of the polymer or the hydrophobic PPO repeat unit of the polymer-hydrophobic inorganic filler of the polymer, the polymer The covalent linkage between the reactive group of the matrix backbone and the reactive group of the dispersant leads to crosslinking, IPN and graft structure. As a result, excessive access of water molecules around the sulfonic acid group is prevented and the water content is reduced. In the manufacturing of the membrane-electrode assembly (MEA) using the polymer composite membrane of the present invention, it is possible to solve the problem of the rapid reduction of the MEA bonding properties and the reduction of fuel cell performance in the water swelling difference between the polymer membrane and the catalyst electrode. Secured. In addition, as the moisture content decreases, the content of methanol permeated with water is reduced, so that barrier property to methanol is secured, and thus the reduced methanol permeability in DMFC applications may lead to high unit cell performance.

2. Increased bound water content and hydrogen ion conductivity in composite membrane

Unlike the decrease in water content, the bound water content, which is a water molecule with high interaction with hydrophilic groups of polymers, surfactants and inorganic fillers, is relatively increased, contributing to the improvement of hydrogen ion conductivity even under conditions of temperature rise and relative humidity. .

3. Improvement of mechanical properties of polymer composite membrane

A polymer composite membrane having a structure as shown in Formula 1, which aids in the dispersion of inorganic materials and is introduced with a surfactant that induces crosslinking, IPN, and graft structure, has a tensile strength and Tensile strength is significantly improved.

4. Improve thermal, hydration and free radical stability of polymer composite membrane

In the case of the manufactured composite membrane, it shows stability under high hydrolysis conditions with improved thermal stability. For example, in the case of pure sulfonated polyimide membrane, in the case of sulfonated polyimide membrane including SiO ₂ -dispersant and sulfonated polyimide membrane containing only a dispersant while having stability of about 3 days at 80 ° C. ultrapure water, It showed hydration stability of more than 146 days and 366 days respectively. In addition, the stability for radical peroxide using 0.1 wt% ferrous ammonium salt + 3 wt% H ₂ O ₂ solution (Fenton's solution) was 28 hours for pure sulfonated polyimide membranes, whereas SiO ₂ -surfactant. , MnO ₂ -surfactant, Al ₂ O ₃ -surfactant and the like showed improved hydration stability of 38 hours, 55 hours, 58 hours, respectively, it was confirmed that the performance is further improved through the combination of the appropriate inorganic fillers.

The surfactant content in the present invention described above is preferably 0.01 or 40 parts by weight based on 100 parts by weight of the polymer film to be prepared, and the effect of adding the surfactant is substantially less than 0.01 part by weight based on 100 parts by weight of the polymer film. It is not preferable because it does not appear, and in addition, when the surfactant exceeds 40 parts by weight with respect to 100 parts by weight of the polymer film, various properties such as hydrogen ion conductivity, methanol permeability, dimensional stability, durability, etc. of the polymer film are proportional to the amount of the surfactant added. It is not economical simply because it does not increase. The polymer composite membrane of the present invention is an inorganic oxide or zirconium such as TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , MnO ₂ , tetraethoxysilane (TEOS), montmorillonite, mordenite, and the like. Most preferably, various inorganic fillers, such as heteropolyacids such as phosphoric acid (ZrP), phosphotungstic acid, silicotungstic acid, phospho molybdic acid, silico molybdic acid and the like, are introduced alone or in combination with surfactants.

In addition, the content of the inorganic filler in the present invention is preferably 0.01 parts by weight or 40 parts by weight to 100 parts by weight of the polymer film, the inorganic filler is less than 0.01 parts by weight based on 100 parts by weight of the polymer film is almost no effect of adding the inorganic filler is preferred. In addition, if the inorganic filler exceeds 40 parts by weight with respect to 100 parts by weight of the polymer membrane, the mechanical properties are not simply increased in proportion to the amount of the inorganic filler added, and thus the breaking property of the prepared membrane is not economical. .

The above-described hydrogen ion conductive polymer composite membrane of the present invention can be used for the preparation of a membrane-electrode assembly (MEA) comprising the same, and the method is a conventional method using a catalyst slurry prepared using a solution containing a catalyst and a suitable binder. It is prepared by application.

In addition, the polymer composite 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. However, it can be preferably used especially for fuel cells.

As described above, the ion conductive polymer composite membrane of the present invention assists in dispersing inorganic materials as a surfactant, and has a hydrophilic and hydrogen-based group having a hydrophilic and hydrogenic group to form a crosslink, an Interpenetrating Polymer Network (IPN), and a graft structure. It is included, the uniform dispersion of the inorganic filler in the polymer electrolyte membrane is induced. In addition, depending on the action of the inorganic filler introduced with the surfactant, the moisture content around the hydrophilic group in the polymer membrane and the dimensional stability is increased. In particular, when the ion conductive polymer composite membrane according to the present invention is used in a direct methanol fuel cell, it may contribute to the reduction of methanol crossover which is directly related to the reduction of fuel cell performance through catalytic poisoning. Unlike the decrease in water content, it leads to an increase in the content of water (bound water, BOUND WATER) having a strong interaction with the reactive groups in the polymer membrane (inorganic oxide), or by itself increasing the HPA content of hydrogen ion conductivity, Contributes to the improvement of hydrogen ion conductivity. In addition, the ion conductive polymer composite membrane of the present invention shows excellent hydration stability and free radical stability depending on the inorganic filler introduced.

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 meta-cresol was added as a solvent. 0.96 g (9.6 mmol) of triethylamine and 0.68 g (5.68 mmol) of benzoic acid were added as a reaction catalyst. After slowly injecting 1.07 g (4 mmol) of 1,4,5,8-naphthalene tetracarboxylic anhydride (NTDA) powder into the completely dissolved solution, completely dissolving and reacting for about 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. Meta The resulting powder was re-cresol (m-cresol) at a temperature of 150 ℃ then dissolved in 9.2 g, silica (Aerosil 200, hydrophilic silica) 0.023g flow to the dispersing agent Nick ^® (Polaxomer 1100, L31) comprises a 0.03g After slowly injecting the solution, 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. to completely remove residual solvent. An opaque sulfonated polyimide composite membrane was prepared. The ion exchange capacity (IEC) of the membrane was 1.80 meq / g.

(Example 2)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.0115 g of silica (Aerosil 200, hydrophilic silica) was used as the inorganic filler.

(Example 3)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.046 g of silica (Aerosil 200, hydrophilic silica) was used as the inorganic filler.

(Example 4)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.069 g of silica (Aerosil 200, hydrophilic silica) was used as the inorganic filler.

(Example 5)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.115 g of silica (Aerosil 200, hydrophilic silica) was used as the inorganic filler.

(Example 6)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.161 g of silica (Aerosil 200, hydrophilic silica) was used as the inorganic filler.

(Example 7)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.23 g of silica (Aerosil 200, hydrophilic silica) was used as the inorganic filler.

(Example 8)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.023 g of alumina (Al ₂ O ₃ ) was used as the inorganic filler.

(Example 9)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.023 g of manganese oxide (MnO ₂ ) was used as the inorganic filler.

(Example 10)

A sulfonated polyimide composite film was prepared in the same manner as in Example 1, except that 0.0115 g of silica (SiO ₂ ) and 0.0115 g of alumina (Al ₂ O ₃ ) were used as the inorganic filler.

(Example 11)

A sulfonated polyimide composite film was prepared in the same manner as in Example 1 except that 0.0115 g of silica (SiO ₂ ) and 0.0115 g of manganese oxide (MnO ₂ ) were used as the inorganic filler.

(Example 12)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.0115 g of alumina (Al ₂ O ₃ ) and 0.0115 g of manganese oxide (MnO ₂ ) were used as the inorganic filler.

(Example 13)

A sulfonated polyimide composite membrane was prepared in the same manner as in Example 1 except that 0.03 g of urethane acrylate nonionomer (UAN) was used as a dispersant.

(Example 14)

2.3 g of sulfonated polyphthalazinone ether sulfone ketone powder prepared by post-sulfonation reaction of commercial polyphthalazinone ether sulfone ketone (PPESK) as a polymer matrix was dissolved in 9.2 g of N-methyl-2-pyrrolidinone and then 150 ° C. in the temperature, silica (Aerosil 200, hydrophilic silica) to flow to the dispersing agent and 0.023g Nick ^® (Polaxomer 1100, L31) was slowly injected into a solution containing 0.03g, was reacted for 8 hours.

After casting the solution on a glass plate, thermal curing at 180 ℃ vacuum oven for 10 hours, and vacuum drying at 110 ℃ vacuum oven for 24 hours to completely remove the residual solvent after having a brown having a thickness of 20-40 ㎛ An opaque sulfonated polyphthalazinone ether sulfone ketone composite membrane was prepared.

(Example 15)

2.3 g of sulfonated poly (aryl ether ketone) powder prepared as presented in Journal of Polymer Science: Part A: Polymer Chemistry 42, 2866-2876 (2004) was dissolved in 9.2 g of N-methyl-2-pyrrolidinone and then heated to 150 ° C. in the temperature, silica (Aerosil 200, hydrophilic silica) to flow to the dispersing agent and 0.023g Nick ^® (Polaxomer 1100, L31) was slowly injected into a solution containing 0.03g, was reacted for 8 hours.

After casting the solution on a glass plate, heat curing at 180 ℃ vacuum oven for 10 hours, and vacuum drying at 110 ℃ vacuum oven for 24 hours in order to completely remove the residual solvent and then opaque brown with a thickness of 30 ㎛ Sulfonated poly (aryl ether ketone) composite membranes were prepared.

(Comparative Example 1)

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

 (Comparative Example 2)

A sulfonated polyphthalazinone ether sulfone ketone membrane was prepared in the same manner as in Example 1, except that Floronic ^® and an inorganic filler were not introduced as the dispersant.

(Comparative Example 3)

A sulfonated poly (aryl ether ketone) membrane was prepared in the same manner as in Example 15 except that Floronic ^® and an inorganic filler were not introduced as the dispersant.

Experimental Example

For the sulfonated polymer film and polymer composite film prepared in Examples 1 to 15 and Comparative Examples 1 to 3, hydrogen ion conductivity (Table 1) according to temperature, hydrogen ion conductivity (Table 2) according to relative humidity, water content (table 3), bound water content (Table 4), methanol permeability (Table 5), selectivity (selectivity, Table 6) and hydration stability (Table 7) were measured and shown in Tables 1-7.

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 / (R × S). . 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 (X10 ^-2 S / cm at 98% RH)

division Temperature (℃) 30 45 60 75 90 Example 1 8.27 8.74 9.33 9.82 10.23 Example 2 7.32 7.87 8.87 9.03 9.55 Example 3 8.40 8.92 9.45 9.98 10.40 Example 4 8.55 9.06 9.59 10.20 10.62 Example 5 8.71 9.19 9.73 10.41 10.86 Example 6 8.87 9.31 9.99 10.63 10.98 Example 7 8.95 9.49 10.20 10.87 11.22 Example 8 7.43 7.93 8.99 9.21 9.76 Example 9 7.56 8.08 9.07 9.34 9.88 Example 10 7.38 7.89 8.93 9.14 9.71 Example 11 7.42 7.90 9.03 9.20 9.81 Example 12 7.50 8.01 9.02 9.29 9.82 Example 13 6.77 7.27 7.80 8.66 9.40 Example 14 6.65 7.11 8.34 8.45 9.28 Example 15 6.21 7.03 7.24 8.29 9.06 Comparative Example 1 5.23 5.80 6.19 6.90 7.33 Comparative Example 2 6.01 6.29 7.79 7.99 8.82 Comparative Example 3 5.11 5.67 6.13 6.76 8.72

As shown in Table 1, when the composite membrane is prepared by adding the surfactant and the inorganic filler at the same time, the temperature rises with the increase of the bound water content having a strong interaction with the reactive group in the polymer membrane compared to the membrane prepared without adding them The hydrogen ion conductivity and the hydrogen ion conductivity compared to the same measured temperature was found to be improved.

[Table 2] Hydrogen ion conductivity according to relative humidity (X10 ^-2 S / cm at 60 ^o C)

division Humidity (% RH) 78 82 90 98 Example 1 5.52 5.93 8.17 9.33 Example 2 5.40 5.84 7.89 8.87 Example 3 5.78 6.23 8.41 9.45 Example 4 6.22 6.37 8.62 9.59 Example 5 6.74 6.93 8.82 9.73 Example 6 6.92 7.01 8.97 9.99 Example 7 7.03 7.41 9.01 10.20 Example 8 5.48 5.91 7.93 8.99 Example 9 5.54 5.98 7.99 9.07 Example 10 5.42 5.87 7.91 8.93 Example 11 5.45 5.89 7.94 9.03 Example 12 5.43 5.88 7.92 9.02 Example 13 4.82 5.78 7.20 7.80 Example 14 4.72 5.70 7.12 8.34 Example 15 4.66 5.62 7.03 7.24 Comparative Example 1 3.80 4.53 5.89 6.19 Comparative Example 2 3.66 4.35 5.73 7.79 Comparative Example 3 3.51 4.29 5.68 6.13

In addition, as shown in Table 2, when the composite membrane was prepared by adding the surfactant and the inorganic filler at the same time, it was found that the hydrogen ion conductivity is also improved at a relative humidity increase and relative humidity compared to the membrane prepared without adding them.

[Table 3] Water content (%)

division Weight before swelling (g) Weight after swelling (g) Moisture content (%) Example 1 1.6329 2.1440 31.3 Example 2 1.3937 1.8134 30.1 Example 3 1.0906 1.4160 30.0 Example 4 1.2386 1.6012 29.3 Example 5 2.1588 2.8531 32.3 Example 6 2.2881 2.9565 29.2 Example 7 1.5286 1.9856 29.9 Example 8 1.7729 2.2792 28.6 Example 9 1.2883 1.6405 27.3 Example 10 1.2893 1.6264 26.2 Example 11 1.6743 2.1503 28.4 Example 12 0.9554 1.2279 28.5 Example 13 1.1514 1.5302 32.9 Example 14 0.9533 1.2272 28.5 Example 15 1.0401 1.3531 30.1 Comparative Example 1 2.0172 2.7071 34.2 Comparative Example 2 1.8975 2.7571 45.3 Comparative Example 3 1.7698 2.5432 43.7

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 the membrane after swelling-weight of the membrane before swelling) / (weight of the membrane before swelling) × 100. As shown in Table 3, it was found that the swelling degree of the sulfonated polymer composite membrane prepared by adding the surfactant and the inorganic filler was also low in water content, thereby obtaining relatively high dimensional stability.

Table 4 Bound Water Content (%)

division Free water (%) Bound Water (%) Example 1 26.7 73.3 Example 2 27.5 72.5 Example 3 23.3 76.7 Example 4 18.7 81.3 Example 5 15.7 84.3 Example 6 15.5 84.5 Example 7 13.1 86.9 Example 8 25.6 74.4 Example 9 24.7 75.3 Example 10 26.2 73.8 Example 11 25.7 74.3 Example 12 25.2 74.8 Example 13 29.9 70.1 Example 14 32.7 67.3 Example 15 37.1 62.9 Comparative Example 1 40.9 59.1 Comparative Example 2 41.9 58.1 Comparative Example 3 43.7 56.3

The content of bound water having a strong interaction force with the reactive group in the polymer was measured 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. (Heat of fusion of endothermic peak at temperature of measurement range) / (heat of fusion of ultrapure water, 344 J / g) x was obtained from the difference of the value of moisture content (%).

As shown in Table 4, the sulfonated polymer composite membrane prepared by adding a surfactant and an inorganic filler in the bound water content is relatively higher than that without adding them, at a temperature rise and the same temperature. It was found that the hydrogen ion conductivity of.

Table 5 Methanol Permeability

division Methanol Permeability (X10 ^-7 cm ² / sec) Example 1 1.48 Example 2 2.31 Example 3 2.34 Example 4 3.64 Example 5 4.32 Example 6 4.92 Example 7 8.61 Example 8 2.37 Example 9 2.42 Example 10 2.34 Example 11 2.37 Example 12 2.39 Example 13 1.39 Example 14 3.09 Example 15 4.82 Comparative Example 1 10.6 Comparative Example 2 28.2 Comparative Example 3 32.8

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 methanol is diffused from one chamber filled with 10 M methanol solution to the other chamber, the other chamber filled with ultrapure water, and then over time from the chamber filled with methanol solution to the chamber filled with only ultrapure water through the polymer membrane, The amount of diffused methanol could be measured using gas chromatography (GC, Shimadtzu, GC-14B, Tokyo, Japan).

As shown in Table 5, in the case of the sulfonated polymer composite membrane prepared by adding the surfactant and the inorganic filler, 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 5.59X10 ⁵ Example 2 3.17 X 10 ⁵ Example 3 3.59X10 ⁵ Example 4 2.34 X 10 ⁵ Example 5 2.01 X 10 ⁵ Example 6 1.80X10 ⁵ Example 7 1.04X10 ⁵ Example 8 3.14 X 10 ⁵ Example 9 3.12 X 10 ⁵ Example 10 3.15 X 10 ⁵ Example 11 3.13 X 10 ⁵ Example 12 3.14 X 10 ⁵ Example 13 4.87X10 ⁵ Example 14 2.15 X 10 ⁵ Example 15 1.29X10 ⁵ Comparative Example 1 4.93X10 ⁴ Comparative Example 2 2.13X10 ⁴ Comparative Example 3 1.56 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. Therefore, 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, it was found that the selectivity of the sulfonated polymer composite membrane prepared by adding the surfactant and the inorganic filler was improved up to 10 times or more.

[Table 7] Sign Language Stability

division Hydration Stability (day) Example 1 > 366 Example 2 > 366 Example 3 > 366 Example 4 > 366 Example 5 > 366 Example 6 > 366 Example 7 > 366 Example 8 > 366 Example 9 > 366 Example 10 > 366 Example 11 > 366 Example 12 > 366 Example 13 > 366 Example 14 > 382 Example 15 > 394 Comparative Example 1 2.9 Comparative Example 2 10.3 Comparative Example 3 16.2

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 carbonic acid group, and a phosphate group, the decomposition | disassembly of a polymer in the hydration state of acidic condition 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 polymer membrane containing no surfactant and the inorganic filler, the problem of low hydration stability, which is a fundamental problem in the fuel cell application of most sulfonated polymer membranes, is observed, but the surfactant and the inorganic filler In the case of the sulfonated polymer composite membrane containing, it was found that the problem of hydration stability of the sulfonated polymer membrane can be fundamentally solved.

[Table 8] Free radical stability

division Free radical stability (time) Example 1 40.9 Example 2 38.3 Example 3 41.3 Example 4 41.8 Example 5 42.3 Example 6 42.8 Example 7 44.7 Example 8 58.4 Example 9 54.7 Example 10 63.7 Example 11 60.9 Example 12 68.6 Example 13 42.3 Example 14 37.5 Example 15 39.4 Comparative Example 1 28.0 Comparative Example 2 23.8 Comparative Example 3 29.4

Free radical stability is another property that must be met in the case of a humidified electrolyte in which hydrogen ions are transferred through water. In other words, it is an index indicating the resistance to H ₂ O ₂ generated when driving a fuel cell, and the measurement of free radical stability is usually a Fenton solution (0.1 wt% ferrous ammonium salt + 3 wt% H ₂ O ₂ solution). After aging the polymer electrolyte at, the free radical stability was evaluated by measuring the time that the polymer electrolyte broke or melted for the first time.

As shown in Table 8, in the case of sulfonated polymer membranes containing no surfactant and inorganic filler, the problem of low free radical stability of most sulfonated polymer membranes was observed, but sulfonated polymer containing surfactant and inorganic filler In the case of the composite membrane, it was found that the free radical problem of the sulfonated polymer membrane can be largely solved.

As described above, the polyelectrolyte composite membrane of the present invention assists in dispersing inorganic materials, and includes a Pluronic or Tetronic polymer surfactant having a hydrophilic and hydrophobic group forming a crosslink, IPN, and a graft structure. Induces uniform dispersion of the inorganic filler in the surfactant, the surfactant can form a unique microstructure, such as crosslinking, IPN, graft structure, depending on the polymer matrix. In addition, depending on the action of the inorganic filler introduced with the surfactant, the moisture content around the hydrophilic group in the polymer membrane and the dimensional stability is increased. In particular, when the polymer electrolyte composite membrane according to the present invention is used in a direct methanol fuel cell, it may contribute to the reduction of methanol crossover which is directly related to the reduction of fuel cell performance through catalyst poisoning. Unlike the decrease in moisture content, it contributes to the increase in the bound water content having a strong interaction with the reactive groups in the polymer membrane (inorganic oxide), or to the hydrogen ion conductivity due to the increase in the HPA content having hydrogen ion conductivity. In addition, the polymer composite membrane of the present invention shows excellent hydration stability and free radical stability depending on the inorganic filler introduced.

Claims (10)

(A) surfactants that help disperse inorganic materials and form crosslinking, IPN, graft structures, including polyethylene oxide (PEO), polypropylene oxide (PPO) or copolymer polymers and oligomers thereof; And (b) inorganic oxides, heteropolyacids (HPA) or mixed inorganic fillers thereof Hydrogen conductive polymer composite membrane comprising a. The method of claim 1, The surfactant is a hydrogen ion conductive polymer composite membrane, characterized in that the terpolymer of PEO and PPO simultaneously containing polyethylene oxide (PEO) as a hydrophilic group, polypropylene oxide (PPO) as a hydrophobic group. The method of claim 1, The inorganic oxides are titanium oxide (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), manganese oxide (MnO ₂ ), tetraethoxysilane (TEOS), montmorillo A hydrogen ion conductive polymer composite membrane, characterized in that it is selected from the group consisting of montmorillonite and mordenite. The method of claim 1, The heteropolyacid (HPA) is a hydrogen ion conductive polymer composite membrane, characterized in that selected from the group consisting of zirconium phosphoric acid, phospho tungstic acid, silico tungstic acid, phospho molybdate acid and silico molybdate acid. The method of claim 1, The content of the surfactant is a hydrogen ion conductive polymer composite membrane, characterized in that 0.01 to 40 parts by weight based on 100 parts by weight of the polymer film. The method of claim 1, The addition amount of the inorganic filler is a hydrogen ion conductive polymer composite membrane, characterized in that 0.01 to 40 parts by weight based on 100 parts by weight of the polymer membrane. The method of claim 1, The hydrogen ion conductive polymer composite membrane is a hydrogen ion conductive polymer composite membrane, characterized in that the fuel cell polymer electrolyte membrane. The method of claim 1, The polymer film material of the polymer composite membrane is a perfluorinated polymer, polyimide, polysulfone, polyarylene ether sulfone, polyarylene ether ketone, polybenzimidazole, polybenzoxazole, polybenzisazole, polypyrrolone, polyether Hydrogen-conductive polymer composite membrane, characterized in that selected from the group consisting of ether ketone and polyphosphazene. (A) surfactants that help disperse inorganic materials and form crosslinking, IPN, graft structures, including polyethylene oxide (PEO), polypropylene oxide (PPO) or copolymer polymers and oligomers thereof; And (b) inorganic oxides, heteropolyacids or mixed inorganic fillers thereof Membrane electrode assembly (MEA) comprising a hydrogen ion conductive polymer composite membrane comprising a. A fuel cell comprising the hydrogen ion conductive polymer composite membrane according to any one of claims 1 to 8.

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