KR20090055737A - Method for producing partially crosslinked hydrogen ion conductive polymer electrolyte membrane, membrane-electrode assembly using partially crosslinked polymer electrolyte membrane prepared therefrom, and fuel cell employing the same - Google Patents

Abstract

A hydrocarbon-based proton conducting copolymer is provided to ensure excellent processability and high content of a hydrophilic group, and to be stable in water and acid while having high ion conductivity. A hydrocarbon-based proton conducting copolymer has a repeating unit represented by chemical formula 1, wherein an inherent viscosity measured on NMP(N-methyl-alpha-pyrrolidinone) of 25 °C is 2.0-3.0 dl/g. In chemical formula 1, A and A' are any one selected from -S-, -CO-, - P(O)Ph-, and -SO2-; B is any one selected from -S-, -C(CH3)2-, -C(CF3)2-, and -SO2-; and a/(a+b) is 0.001-1.0.

Description

Method for producing partially cross-linked hydrogen ion conductive polymer electrolyte membrane, membrane-electrode assembly using partially cross-linked polymer electrolyte membrane prepared therefrom, and fuel cell employing the same CROSSLINKED TYPE POLYMER MEMBRANES MANUFACTURED THEREBY AND FUEL CELL HAVING THEM}

The present invention relates to a method for producing a partially cross-linked hydrogen ion conductive polymer electrolyte membrane, a membrane-electrode assembly using the partially cross-linked polymer electrolyte membrane prepared therefrom, and a fuel cell employing the same, and more particularly, a raw material for a partial crosslinking reaction. By providing a novel hydrocarbon-based ion-conducting copolymer and partially crosslinking a bifunctional aromatic vinyl compound to the polymer electrolyte membrane prepared from the copolymer, a membrane-electrode having excellent performance with improved dimensional stability and mechanical properties of the membrane It relates to a bonded body and a fuel cell employing the same.

Fuel cell is a power generation device that directly converts chemical energy into high-efficiency and high-density electrical energy through oxidation and reduction reactions. It is the latest technology in various fields such as electrolyte membrane, catalyst, electrode, separator, stack, balance of plant (BOP), etc. This is the next generation of high density clean energy conversion system. A fuel cell mainly uses hydrogen as a fuel and generates electric power by an ion concentration gradient difference of hydrogen and electrons generated by oxidation of fuel material and oxygen. The overall reaction of a fuel cell corresponds to a kind of oxidation-reduction reaction, which generates water as the only reaction by-product, and thus is attracting attention as an eco-friendly technology with little emission of pollutants.

Fuel cells may be molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), phosphoric acid fuel cells (PAFCs), or alkaline, depending on the type of electrolyte and operating temperature. It is classified into an alkaline fuel cell (AFC) and a polymer electrolyte fuel cell (PEFC).

In particular, a polymer electrolyte fuel cell refers to a fuel cell using an ion conductive polymer membrane as an electrolyte, and a direct ion methanol (PEMFC) proton exchange membrane fuel cell (PEMFC) and methanol as a fuel. DMFC (direct methanol fuel cell) is a typical example. Since the polymer electrolyte fuel cell uses a hydrogen ion conductive polymer membrane (PEM) as the electrolyte, there is no electrolyte loss, and it is not influenced by the pressure change of the reactor, and the same principle of operation is the phosphate fuel cell. While the volume is considerably smaller than that, in terms of performance and efficiency, it is highly dependent on the basic characteristics of the membrane-electrode assembly and the polymer electrolyte membrane employed therein.

The polymer electrolyte fuel cell has a basic composition of a polymer electrolyte membrane, a fuel electrode, and an air electrode. Hydrogen introduced into the anode is oxidized by a catalyst and separated into hydrogen ions (H ⁺ ) and electrons (e ⁻ ), and are moved to the cathode through the electrolyte and the external circuit, respectively. Oxygen introduced into the cathode reduces the hydrogen ions transferred through the electrolyte membrane to generate water and heat, and electrical energy is generated by electrons moved through the external circuit in the process. At this time, the oxidation-reduction reaction and the total reaction generated at each electrode are as follows.

Equation 1:

A fuel electrode _{(Anode): H 2 → 2H} + + 2e -

Equation 2:

Cathode _{(Cathode): 1 / 2O 2} + 2H + + 2e - → H 2 O + heat

Equation 3:

Total reaction: H ₂ + 1 / 2O ₂ → H ₂ O + heat

The role of the polymer electrolyte membrane can be broadly divided into two roles, one of which is a carrier for transporting hydrogen ions from an anode to a cathode, and the other of a separator that effectively separates fuel and reactant gases. Role. Accordingly, the polymer electrolyte membrane is preferably a thin film having a thickness of 50 to 175 μm, which exhibits high density and low porosity. The polymer electrolyte membrane has a high mechanical stability and excellent compatibility with electrodes, thus making it difficult to manufacture a membrane-electrode assembly. There should be no. Furthermore, it should maintain stable performance without remarkable power change even in high temperature low-humidity operation, non-humidification operation, and long-term repetitive operation of over 80 ℃, and excellent thermal, physical and chemical resistance even in high temperature and strong acidic operation environment.

)과 플레미온(Flemion

) 등의 불소계 이온 교환막이 채용되어 사용되어 왔으나, 제조비용이 높고, 독성의 중간 생성물이 발생되며, 연료 및 메탄올 투과도가 높을 뿐 아니라, 함수율 감소로 인한 고온에서의 이온 전도도 감소 등의 문제점이 지적되고 있다. 따라서, 상기 불소계의 고분자 전해질 막을 대체하고, 고분자 전해질형 연료전지에 원만히 적용하기 위하여, 최근의 연구방향은 폴리술폰(polysulfone)계, 폴리에테르술폰[poly(ether sulfone)]계, 폴리에테르케톤[poly(ether ketone)]계, 폴리이미드(polyimide)계 등과 같은 비불소계 내열성 고분자에 술폰기를 도입시킨 이오노머(ionomer) 형태의 고분자 전해질 막 연구에 집중되고 있다. 즉, 상기 비불소계 고분자 전해질 막으로서 술폰화된 폴리술폰, 폴리에테르술폰, 폴리아릴렌에테르술폰, 폴리에테르에테르케톤 및 폴리프탈라지논에테르설폰케톤 등의 제조방법을 제시하고, 이들의 이온 전도도 향상 및 연료전지 전해질 막으로의 적용성에 관하여 다수에 의해 보고되고 있다[J. Membr. Sci., 197 (2002) 231; J. Membr. Sci., 185 (2001) 73; J. Electrochem. Soc., 151(21) (2004) A2150; Micromol. Symp., 175 (2001) 387; J. Membr. Sci., 281 (2006) 121, 미합중국 특허등록 제2005-26144호, 제2006-134493호 및 미합중국 특허공개 제5,438,082호 및 제 6,245,881호]. Currently, most fuel cells have developed and commercialized Nafion in the United States and Japan.

) And Flemion

Although fluorine-based ion exchange membranes have been employed, they have high manufacturing costs, toxic intermediate products, high fuel and methanol permeability, and low ion conductivity at high temperatures due to reduced water content. It is becoming. Therefore, in order to replace the fluorine-based polymer electrolyte membrane and to apply it to a polymer electrolyte fuel cell smoothly, recent research directions include polysulfone, polyether sulfone, and polyether ketone. It is focused on the research of ionomer-type polymer electrolyte membranes in which sulfone groups are introduced into non-fluorinated heat-resistant polymers such as poly (ether ketone)] and polyimide. That is, as the non-fluorine-based polymer electrolyte membrane, a sulfonated polysulfone, polyethersulfone, polyarylene ether sulfone, polyether ether ketone, polyphthalazinone ether sulfone ketone, and the like are proposed. And applicability to fuel cell electrolyte membranes have been reported by a number [ J. Membr. Sci ., 197 (2002) 231; J. Membr. Sci ., 185 (2001) 73; J. Electrochem. Soc ., 151 (21) (2004) A2150; Micromol. Symp ., 175 (2001) 387; J. Membr. Sci ., 281 (2006) 121, US Patent Registration Nos. 2005-26144, 2006-134493 and US Patent Publication Nos. 5,438,082 and 6,245,881].

However, in the non-fluorine-based polymer electrolyte membrane, dehydration reaction proceeds easily around the sulfone groups introduced into the aromatic compound in the polymer in an acid or heat environment, resulting in a decrease in ion conductivity at 80 ° C. or higher as the water content decreases.

In order to solve these problems, a method of improving the physico-chemical properties of a polymer electrolyte membrane through a crosslinking reaction using multi-functional chemicals having two or more functional groups has been proposed [ J. Membr. Sci ., 283, 1-2 (2006) 373; J. Org. Chem ., 56 (1991) 5540, U.S. Patent Nos. 2006-281824, 2005/0019638, 4,594,459, 4,992,151, Japanese Patent 2002-348389 and European Patent 1,160,903], Publication No. 2005-72183 has also suggested various types of multifunctional candidates.

However, the conventional method introduced to improve the properties of the polymer electrolyte membrane results in a decrease in the concentration of the hydrophilic ion exchange groups distributed in the polymer electrolyte membrane, thereby lowering the ionic conductivity while increasing the concentration of the hydrophilic functional group to improve the ionic conductivity. In this case, the mechanical properties of the electrolyte membrane are greatly reduced. In addition, since a series of manufacturing processes proceed in several steps and complex detailed processes, it is difficult to secure economic feasibility until commercialization.

Accordingly, the present inventors have endeavored to obtain a polymer electrolyte membrane having a significantly improved mechanical properties while maintaining a high level of ionic conductivity. As a result, the hydrocarbon-based ion-conducting polymer having physically-chemical stability and excellent processability despite the relatively high hydrophilic group content Partially cross-linked hydrogen ion conductive polymer that provides a copolymer and has a high ionic conductivity and improved mechanical properties by a simple manufacturing process of directly crosslinking a 2-functional aromatic vinyl compound on a polymer electrolyte membrane prepared from the copolymer. Providing an electrolyte membrane, confirming the performance of the polymer electrolyte membrane excellent enough to replace the conventional commercially available polymer electrolyte membrane, to prepare a membrane-electrode assembly using the partially cross-linked hydrogen ion conductive polymer electrolyte membrane, and further, Direct membrane-electrode assembly By employing all the fuel cell or a proton exchange membrane fuel cell, a full efficiency and reliability is maintained even at high temperatures and acidic environment of the fuel cell, thereby completing the present invention.

An object of the present invention is to provide a hydrocarbon-based hydrogen ion conductive copolymer having a high content of hydrophilic groups, having high ionic conductivity, stable to water and acid, and having excellent processability.

Another object of the present invention is to provide a method for producing a partially cross-linked hydrogen ion conductive polymer electrolyte membrane, which is a cross-linking reaction of a polymer electrolyte membrane prepared using the hydrocarbon-based hydrogen ion conductive copolymer and a 2-functional aromatic vinyl compound. will be.

It is still another object of the present invention to provide a membrane-electrode assembly composed of a partially cross-linked hydrogen ion conductive polymer electrolyte membrane prepared by the above method, and a polymer electrolyte fuel cell employing the same in a methanol fuel cell or a hydrogen ion exchange membrane fuel cell. Is to provide.

In order to achieve the above object, the present invention provides a hydrocarbon-based hydrogen ion conductive copolymer having a repeating unit represented by the following formula (1), the intrinsic viscosity measured on NMP at 25 ℃ 2.0 to 3.0 dl / g. .

Formula 1

(In the above, A and A 'are overlapping or cross-selected in the group consisting of -S-, -SO _2- , -C = O- and -P (O) (C ₆ H ₅ )-, for B- , -S-, -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -and -SO _2- , any one selected from the group consisting of a / (a + b) is 0.001 to 1.0, c is the degree of polymer polymerization which increases proportionally as the molecular weight of the copolymer increases.)

The sulfonation degree of the sulfonated polyarylene ether sulfone copolymer of the present invention is 55 to 70%.

In addition, the present invention is to prepare a solution by dissolving the hydrocarbon-based hydrogen ion conductive copolymer in an organic solvent, cast on a glass or Teflon plate, and then dried to produce a film thickness of 30 to 50 ㎛ Provided is a method for producing a polymer electrolyte membrane.

Furthermore, the present invention is a hydrogen ion conductive polymer electrolyte membrane prepared from the above production method, the reaction solution containing any one selected from the group of 2-functional aromatic vinyl compound represented by the following formula (2) at 80 to 120 ℃ 1 Soaking for 12 to 12 hours, the bi-functional aromatic vinyl compound is partially crosslinked to the hydrogen-ion conductive polymer electrolyte membrane, and after the immersion, partially crosslinked consisting of acid treatment with 0.5M sulfuric acid aqueous solution Provided is a method for producing a hydrogen ion conductive polymer electrolyte membrane.

The 2-functional aromatic vinyl compound is any one selected from the group of 2-functional aromatic vinyl compounds represented by the following Formula 2, and the reaction solution is 1 to 50% by weight of the 2-functional aromatic vinyl compound Is prepared by dissolving in an organic solvent.

Formula 2

At this time, the organic solvent is any one selected from the group consisting of methanol, ethanol, isopropanol and butanol when the 2-functional aromatic vinyl compound is a liquid phase, and when the 2-functional aromatic vinyl compound is a solid phase, Any one selected from the group o-xylene, m-xylene and p-xylene is used.

The present invention is prepared by the method of preparing the partially cross-linked hydrogen ion conductive polymer electrolyte membrane, wherein the reaction solution containing the 2-functional aromatic vinyl compound is 0.01 to 25% by weight per unit mass of the hydrogen ion conductive polymer electrolyte membrane. And a thickness increase of 10 to 80% per unit thickness is generated to provide a partially crosslinked hydrogen ion conductive polymer electrolyte membrane having a thickness of 40 to 60 μm of the final partially crosslinked hydrogen ion conductive polymer electrolyte membrane.

Furthermore, there is provided a membrane-electrode assembly composed of the partially cross-linked hydrogen ion conductive polymer electrolyte membrane and a polymer electrolyte fuel cell employing the same in a methanol fuel cell or a polymer electrolyte fuel cell.

The present invention provides a sulfonated polyarylene ether sulfone copolymer having a sulfonation degree of 55 to 70% as a hydrocarbon-based hydrogen ion conductive copolymer, so that the hydrophilic group is contained in a high concentration and is not dissolved in boiling water and acid, Excellent workability, it is possible to produce a hydrogen-ion conductive polymer electrolyte membrane that does not deform even when producing a thin film of up to 20 ㎛ thickness.

Accordingly, the present invention by directly reacting a bi-functional aromatic vinyl compound to the hydrogen ion conductive polymer electrolyte membrane, to prepare a partially cross-linked hydrogen ion conductive polymer electrolyte membrane in a simple manufacturing process, thereby improving the dimensional stability and mechanical properties of the membrane Excellent performance membrane-electrode assemblies can be prepared.

Furthermore, the present invention employs a membrane-electrode assembly directly in a methanol fuel cell or a hydrogen ion exchange membrane fuel cell, thereby improving the overall efficiency of the fuel cell and allowing long-term operation because it is stable even at a high temperature of 80 ° C. or higher in an acidic environment. A polymer electrolyte fuel cell can be provided.

Hereinafter, the present invention will be described in detail.

The present invention provides a hydrocarbon-based hydrogen ion conductive copolymer having a repeating unit represented by the following Chemical Formula 1, having an intrinsic viscosity of 2.0 to 3.0 dl / g measured on NMP at 25 ° C.

Formula 1

(In the above, A and A 'is any one selected from the following functional groups, can be duplicated or cross-selected,

B is any one selected from the following functional groups,

a / (a + b) is 0.001 to 1.0, and c is a degree of polymer polymerization which increases proportionally as the molecular weight of the copolymer increases.)

The hydrocarbon-based hydrogen ion conductive copolymer of the present invention is a sulfonated polyarylene ether sulfone copolymer having a sulfonation degree of 55 to 70%, and is used as a starting material of a partially crosslinked polymer electrolyte membrane.

That is, the intrinsic viscosity of the copolymer represented by the formula (1) used as a raw material for preparing the partially crosslinked polymer electrolyte membrane of the present invention is 25 ℃ in order to meet the requirement that it should not be dissolved in water or a fuel cell working solvent such as methanol. The range of 0.8 or more and 3.0 dl / g on NMP is preferable, More preferably, it is 2.0-3.0 dl / g.

At this time, if the viscosity of the copolymer used as a raw material for preparing the partially crosslinked polymer electrolyte membrane is less than 0.8 dl / g, fine cracks are generated while the physical strength of the prepared membrane is lowered, making it difficult to apply the polymer electrolyte membrane for fuel cells. In the case of more than 3.0 dl / g, the solubility of the copolymer per solvent volume of the solvent decreases, so that solution preparation, uniform dispersion, and solvent release to the surface of the membrane are not smooth, thereby forming a non-uniform and porous film.

In addition, when the viscosity of the copolymer is less than 2.0 dl / g, the maximum amount of sulfone groups introduced into the copolymer is limited, and more specifically, the degree of sulfonation of the copolymer having an intrinsic viscosity of 2.0 dl / g or less Is known to dissolve in boiling water or acid when at least 50%. On the other hand, the sulfonated polyarylene ether sulfone copolymer of the present invention is confirmed the degree of sulfonation of the copolymer through ¹ H NMR (nuclear magnetic resonance) analysis, the sulfonation degree of the copolymer is 55 to At 70%, there is no mass loss or morphological change in boiling water or acid [not shown]. In addition, it is excellent in workability and mechanical properties, it is possible to produce a hydrogen ion conductive polymer electrolyte membrane that does not deform even at a thin film thickness of up to 20 ㎛.

Method for producing a hydrocarbon-based hydrogen ion conductive copolymer having a repeating unit represented by the formula (1) is the same as in Scheme 1.

(In the above, A, A ', B, a, b and c in the monomer are as defined above and Z is a halogen group element of F or Cl or -NO ₂ as leaving group in the copolymerization reaction.)

Furthermore, a method of producing a hydrogen-ion conductive polymer electrolyte membrane in which the hydrocarbon-based hydrogen ion conductive copolymer is dissolved in an organic solvent to prepare a solution, cast on a glass or teflon plate, and then dried to prepare a thickness of 30 to 50 μm. To provide.

In addition, the present invention 1) to prepare a hydrogen ion conductive polymer electrolyte membrane prepared using a hydrocarbon-based hydrogen ion conductive copolymer represented by Formula 1,

2) preparing a reaction solution containing any one selected from the group of 2-functional aromatic vinyl compounds represented by the following Formula 2,

3) the hydrogen ion conductive polymer electrolyte membrane is immersed in the reaction solution at 80 to 120 ° C. for 1 minute to 12 hours to partially crosslink the bifunctional aromatic vinyl compound to the hydrogen ion conductive polymer electrolyte membrane. ,

4) After the immersion, it provides a method for producing a partially cross-linked hydrogen ion conductive polymer electrolyte membrane consisting of acid treatment with 0.5M sulfuric acid aqueous solution.

Formula 2

In the above production method, the electrolyte membrane used as a raw material for preparing the partially crosslinked polymer electrolyte membrane in step 1) can be freely prepared in a sulfonated polyarylene ether sulfone copolymer with a film thickness of 10 to 200 μm, In consideration of the increase in thickness of the generated electrolyte membrane, it is preferable to adjust the thickness of the crosslinked final electrolyte membrane to be in the range of 40 to 60 μm.

At this time, when the thickness of the partially cross-linked final electrolyte membrane is less than 40 μm, permeation of fuel and reaction gas occurs through the membrane to decrease the efficiency of the fuel cell, and when it exceeds 60 μm, the transfer path of hydrogen ions is excessively increased to increase the unit. The resistance of the battery increases.

The reaction solution of step 2) is prepared by dissolving 1 to 50% by weight of a 2-functional aromatic vinyl compound in an organic solvent, wherein the organic solvent used is a liquid phase in which the 2-functional aromatic vinyl compound is in a liquid phase. ) Is selected from the group of alcohols such as methanol, ethanol, isopropanol, butanol and the like and from the o-xylene, m-xylene and p-xylene groups in the solid phase.

In addition, when the content of the 2-functional aromatic vinyl compound is less than 1% by weight, the partial crosslinking effect is remarkably lowered, and when the content of the bifunctional aromatic vinyl compound is greater than 50% by weight, the cross-linking reaction results in homo-polymerization between the vinyl monomers. The reaction solution is hardened.

In step 3), the hydrogen ion conductive polymer electrolyte membrane is immersed in the reaction solution at 80 to 120 ° C. for 1 minute to 12 hours, so that the 2-functional aromatic vinyl compound is partially crosslinked to the hydrogen ion conductive polymer electrolyte membrane. This is to make sure.

At this time, the crosslinking allows any one of the 2-functional aromatic vinyl compound selected from the group of Formula 2 to be introduced at 0.01 to 25% by weight per unit mass of the raw material electrolyte membrane prepared in step 1). More preferably, the maximum crosslinking weight is limited to within 10% by weight for application to a polymer electrolyte membrane for a polymer electrolyte fuel cell. At this time, within 10% by weight of the cross-linking weight increases the mechanical properties of the electrolyte membrane proportionally, and the permeation of the fuel and the reaction gas is reduced, but if it exceeds 10% by weight, the resistance of the electrolyte membrane is greatly increased Significant decreases in ionic conductivity and unit cell performance are observed, and the hardness of the membrane is excessively increased, which leads to difficulty in manufacturing the membrane-electrode assembly.

In addition, a partially crosslinked high molecular electrolyte membrane is prepared in which the thickness of the polymer electrolyte membrane is increased by 10 to 80% per unit thickness. More preferably, the thickness of the final partially cross-linked hydrogen ion conductive polymer electrolyte membrane is made from 40 to 60 μm.

When the crosslinking reaction is completed, the electrolyte membrane is separated from the reaction solvent, the remaining reactant is extracted and washed several times with the organic solvent used in the reaction, dried in a vacuum dryer at 50 ℃ until no further weight loss, The weight and thickness of the electrolyte membrane before and after the crosslinking reaction were measured.

In the step 4), the partially cross-linked hydrogen ion conductive polymer electrolyte membrane is subjected to final acid treatment at 100 ° C. in 0.5M sulfuric acid solution for 2 hours or more, thereby obtaining high hydrogen ion conductivity.

)막에 대비하여, 대등하거나 보다 높은 이온 전도도를 보인다. 2 is a result of measuring the ionic conductivity of the Nafion membrane compatible with the partially cross-linked polymer electrolyte membrane and the non-crosslinked polymer electrolyte membrane for the raw material of the present invention, the polymer electrolyte membrane of the present invention is a commercial Nafion 112

In contrast to membranes, they exhibit comparable or higher ionic conductivity.

)막에 대하여, 동일한 조건에서의 인장강도를 측정한 결과, 본 발명에 의한, 부분 가교된 수소이온 전도성 고분자 전해질 막의 경우, 상용 나피온 막보다 현저히 우수한 기계적 물성을 보인다. 3 is Nafion-112 compatible with the partially crosslinked polymer electrolyte membrane of the present invention and the polymer electrolyte membrane for non-crosslinked raw materials (Nafion-112).

The tensile strength of the membrane was measured under the same conditions. As a result, the partially cross-linked hydrogen ion conductive polymer electrolyte membrane according to the present invention showed significantly superior mechanical properties than commercial Nafion membranes.

)막에 대하여 대등하거나 우수한 이온 전도도 및 기계적 안정성을 확인할 수 있으며, 특히, 가교되지 않는 원료용 고분자 전해질 막에 2 관능성의 방향족 비닐계 화합물이 부분적으로 가교되어 제조된 부분 가교된 수소이온 전도성 고분자 전해질 막은 막의 치수 안정성(dimensional stability) 및 기계적 특성(mechanical property)이 우수하다.Therefore, the partially crosslinked polymer electrolyte membrane of the present invention and the non-crosslinked polymer electrolyte membrane for raw materials are commonly used Nafion-112.

Particularly crosslinked hydrogen ion conductive polymer electrolyte prepared by partial crosslinking of bifunctional aromatic vinyl compounds in the polymer electrolyte membrane for raw materials that are not crosslinked can be confirmed to have a similar or superior ionic conductivity and mechanical stability to the membrane. Membranes have good dimensional stability and mechanical properties.

The present invention provides a membrane-electrode assembly composed of the partially cross-linked hydrogen ion conductive polymer electrolyte membrane and a fuel cell employing the membrane-electrode assembly in a direct methanol fuel cell (DMFC).

In particular, when the membrane-electrode assembly is employed in a direct methanol fuel cell (DMFC), water uptake and methanol crossover may be lowered to improve overall efficiency of the direct methanol fuel cell. have.

In addition, when the membrane-electrode assembly is employed in a proton exchange membrane fuel cell (PEMFC), thermal stability and oxidation stability are improved, resulting in high temperature of 80 ° C. or higher and strong acidity. Since it is stable in the environment, the fuel cell can be operated for a long time.

)막에 대한 단위 전지 성능 평가 결과로서, 본 발명의 부분 가교된 고분자 전해질 막의 경우, 전류밀도가 높고, 낮은 전지 전압강하 특성을 나타낸다. 4 is Nafion-112 compatible with the partially cross-linked polymer electrolyte membrane of the present invention and the non-crosslinked raw material polymer electrolyte membrane (Nafion-112).

As a result of evaluation of unit cell performance for the membrane, the partially crosslinked polymer electrolyte membrane of the present invention exhibits high current density and low battery voltage drop characteristics.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Example 1> Preparation of sulfonated arylether sulfone polymer electrolyte membrane having sulfonation degree of 60%

Step 1: preparation of sulfonated arylether sulfone copolymer having a sulfonation degree of 60%

A 300 ml branched round bottom flask was fitted with a gas inlet, thermometer, Dean-Stark trap, cooler and stirrer, and after removing sufficient gaseous impurities in a nitrogen atmosphere, BP (4,4'-biphenol) 9.9239 g (53.3 mmol), 5.4200 g (21.3 mmol) difluorodiphenyl sulfone (DFDPS; 4,4'-difluorodiphenyl sulfone), sulfonated difluorodiphenyl sulfone (SDFDPS; 3,3'-disulfonated-4,4'- 14.6561 g (32.0 mmol) of difluorodiphenyl sulfone), 8.9126 g (64.5 mmol) of K ₂ CO ₃ , 120 ml of dimethylacetamide (DMAc; N, N-dimethylacetamide) and 60 ml of toluene were added together and stirred at 80 ° C. for 2 hours. To completely dissolve the monomer. The temperature of the reaction solution was maintained at 140 ° C. and maintained for 4 hours. Then, all of the water and toluene generated during the reaction were removed using a Dean-Stark trap, followed by reaction at 160 ° C. for 3 hours. After the reaction was completed, the reaction solution was diluted with 20 ml of DMAc, filtered, and precipitated in tertiary distilled water to obtain a copolymer precipitate in the form of swollen fiber (swollen fiber). The copolymer separated from distilled water was washed and filtered several times, followed by drying under reduced pressure, thereby obtaining a sulfonated arylether sulfone copolymer (SPAES-60) having a sulfonation degree of 61.2% and an intrinsic viscosity of 2.89 dl / g. The sulfonation degree was determined by ¹ H NMR analysis, the intrinsic viscosity is the value measured through a capillary viscometer on 25 ℃, NMP. A schematic representation of the preparation method is shown in Scheme 2 below, ¹ H NMR analysis was performed to confirm the chemical structure and sulfonation degree of the prepared SPAES-60 copolymer, and the results are shown in FIG. 1 .

(In the above, k is a proportional constant greater than 0.)

Step 2: Preparation of Polymer Electrolyte Membrane Using Sulfonated Aryl Ether Sulfone Copolymer with Sulfonation Degree of 60%

0.80 g of the salt-form SPAES-60 copolymer synthesized through Scheme 2 was dissolved in 8 ml of purified NMP solvent and filtered through a 0.45 μm pore Teflon filter to give 10-weight / volume. A copolymer solution for preparing a membrane of% (w / v%) was prepared. The prepared solution is poured into a clean glass or Teflon plate without surface scratches, dried slowly over 12 hours using a halogen lamp in an inert gas atmosphere at 60 ° C, and then dried in a reduced pressure dryer at 120 ° C for at least 12 hours. By completely removing the solvent used in the preparation, a polymer electrolyte membrane made of SPAES-60 copolymer (salt-form) for raw materials of the partial crosslinking reaction was prepared.

<Comparative Examples 1 to 3> Preparation of sulfonated arylether sulfone polymer electrolyte membrane

In step 1 of Example 1, the ratio of BP / (DFDPS + SDFDPS) of the monomers is fixed to 1/1, and the mixing ratio of SDFDPS is adjusted to 10, 30, 50 mol% with respect to the DFDPS. Sulfonated polyaryl ether sulfone polymer (SPAES-10, 30, 50) except that the preparation and use of the same method as in Example 1, the sulfonation degree-10%, 30%, 50% A polymer electrolyte membrane made of an aryl ether sulfone polymer was prepared. In this case, the mixing ratio of the sulfonated polyarylethersulfone polymer and the properties of the hydrogen ion conductive polymer electrolyte membrane prepared therefrom are shown in Table 1 below.

< Example  2-7 parts Crosslinked Hydrogen ion  Preparation of Conductive Polymer Electrolyte Membrane

15 ml of divinylbenzene (DVB; 1,4-divinylbenzene) and 15 ml of ethanol were added to a 50 ml reaction ampoule, and after purging with argon gas for 5 minutes, the film thickness prepared in Example 1 was 41.2 μm. After immersing the polymer electrolyte membrane consisting of SPAES-60 (salt-form, 38 mg) of the copolymer was further purged for 5 minutes. Thereafter, the reaction ampoule was placed in a thermostat fixed at 80 ° C. and maintained for 30 minutes, after which the crosslinked electrolyte membrane was separated from the reaction solution, extracted and washed several times with ethanol, and when there was no further weight loss on the drying pressure reducing plate. To dry. The cross-linked electrolyte membrane in the sodium salt form was acid treated at 100 ° C. in 0.5 M sulfuric acid solution for 2 hours or more to prepare a partially cross-linked hydrogen ion conductive polymer electrolyte membrane having high hydrogen ion conductivity and improved mechanical strength. .

The polymer electrolyte membrane composed of the SPAES-60 copolymer prepared in Example 1 was carried out under the conditions shown in Table 2 to prepare a partially cross-linked hydrogen ion conductive polymer electrolyte membrane, and the characteristics of the membrane were described.

< Example  8>

Except for using diisopropenylbenzene (DIPB; 1,4-diisopropenyl benzene) instead of divinylbenzene involved in the crosslinking reaction in Example 2, except that the organic solvent is used as p-xylene, A partially cross-linked hydrogen ion conductive polymer electrolyte membrane was prepared in the same manner as in Example 2.

Experimental Example 1 Ion Conductivity Measurement

)막간의 성능을 비교하기 위하여, 가교되지 않는 원료용 고분자 전해질 막, 부분 가교된 전해질 막 및 상용된 나피온(Nafion-112

)에 대하여, 25∼80℃의 온도 범위에서 동일한 과정을 거쳐 이온 전도도를 측정하였다. Nafion compatible with the partially cross-linked hydrogen ion conductive polymer electrolyte membrane prepared in Examples 2 to 7 (Nafion-112

To compare the performance between the membranes, a polymer electrolyte membrane for a raw material that is not crosslinked, a partially crosslinked electrolyte membrane, and a commercially available Nafion-112

), The ion conductivity was measured in the same range in the temperature range of 25 ~ 80 ℃.

) 두께의 ±5% 이내로 조절하여 제조하였다. In this case, a polymer electrolyte membrane composed of sulfonated arylether sulfone (SPAES-60) having a sulfonation degree of 60% prepared in Example 1 and a partially crosslinked hydrogen ion conductive polymer electrolyte membrane prepared in Example 4 were used. By adjusting the thickness of the membranes and the crosslinking reaction conditions, the thickness of the final electrolyte membrane was changed to Nafion 112.

) Was prepared to adjust within ± 5% of the thickness.

Ion conductivity was measured using a Solartron analyzer (Solatron 1260 Impedance / Gain-Phase analyzer) and the impedance spectrum was recorded up to 10MHz ~ 10Hz, the ion conductivity was calculated by the following equation (1).

Ion conductivity (S / cm); ∂ = 1 / R × L / A

(In the above, δ, S is the distance between the measuring electrodes (1 cm), R is the measuring resistance (ohm), L is the length (cm) between the measuring electrodes, A is the cross-sectional area (cm ² ) of the prepared electrolyte membrane. .)

)막에 대한 이온전도도의 결과로서, 가교되지 않는 원료용 고분자 전해질 막(실시예 1)과 부분 가교된 수소이온 전도성 고분자 전해질 막(실시예 4)은 동일 측정 조건에서, 동등한 두께의 상용 나피온(Nafion 112

)막에 대비하여, 대등하거나 보다 높은 이온 전도도 특성을 나타내었다. 2 is a cross-linked polymer electrolyte membrane of the present invention and a non-crosslinked polymer electrolyte membrane for raw materials, and Nafion is commonly used (Nafion-112

As a result of the ion conductivity of the membrane, the non-crosslinked polymer electrolyte membrane for raw material (Example 1) and the partially cross-linked hydrogen ion conductive polymer electrolyte membrane (Example 4) were commercially available Nafion of equal thickness under the same measurement conditions. (Nafion 112

Compared to the membrane, it showed comparable or higher ionic conductivity properties.

Experimental Example 2 Methanol Permeability Measurement

Methanol permeability was measured by placing the electrolyte membrane in the interconnection path of two vessels containing a constant concentration of methanol and water at right angles to the fluid flow, and then measuring the concentration of methanol permeated through the membrane at a measurement temperature of 30 ° C. It was measured at regular intervals throughout, and from this the permeation coefficient of methanol was calculated according to the following equation (2).

Methanol permeability (methanol crossover, cm ² / s); P = a, VB, L / A, CA

(In the above, a is the slope in the time-concentration graph, VB is the volume of methanol permeated (cm ³ ), L is the thickness of the electrolyte membrane (cm), A is the area of the electrolyte membrane (cm ² ), CA Is the concentration of methanol used.)

) 막에 대하여, 동등 막 두께에서 메탄올 투과도가 최대 30% 이하로 감소하였다.As a result, the methanol permeability of the partially cross-linked hydrogen ion conductive polymer electrolyte membrane of the present invention was measured. As a result, Nafion 112 is compatible with the acid-treated polymer electrolyte membrane (SPAES-60).

For membranes, methanol permeability decreased up to 30% at equivalent membrane thicknesses.

Experimental Example 3 Mechanical Property Evaluation

) 막을 각각 1×10 (W×L, cm) 크기로 절단한 후, 시험 장비(인스트론-5755)를 이용하여 ASTM D412 시험법에 기준하여 비교 평가하였다. 이 때, 시료로는 상기 실시예 1에서 제조된 술폰화도가 60%인 술폰화아릴에테르술폰(SPAES-60)으로 이루어진 고분자 전해질 막 및 실시예 4에서 제조된 부분 가교된 수소이온 전도성 고분자 전해질 막을 사용하였다. In order to evaluate the mechanical properties of the prepared partially cross-linked hydrogen ion conductive polymer electrolyte membrane, the cross-linked polymer electrolyte membrane, non-crosslinked raw polymer electrolyte membrane and commercially available Nafion 112

) The membranes were cut into 1 × 10 (W × L, cm) sizes, respectively, and then evaluated using the test equipment (Instron-5755) based on the ASTM D412 test method. At this time, the sample is a polymer electrolyte membrane consisting of sulfonated arylether sulfone (SPAES-60) having a sulfonation degree of 60% prepared in Example 1 and a partially cross-linked hydrogen ion conductive polymer electrolyte membrane prepared in Example 4 Used.

)막에 대하여, 동일한 조건에서의 인장강도 특성평가를 수행한 결과, 가교되지 않은 고분자 전해질 막(실시예 1)의 기계적 강도는 나피온 막보다 낮았으나, 본 발명에 의한 부분 가교된 수소이온 전도성 고분자 전해질 막의 경우, 상용 나피온 막보다 현저히 우수한 기계적 물성을 나타내었다. 3 is a cross-linked polymer electrolyte membrane of the present invention and a non-crosslinked polymer electrolyte membrane for raw materials, and Nafion is commonly used (Nafion-112

The mechanical strength of the uncrosslinked polymer electrolyte membrane (Example 1) was lower than that of the Nafion membrane, but the partially crosslinked hydrogen ion conductivity according to the present invention was obtained. In the case of the polymer electrolyte membrane, mechanical properties were significantly better than those of the commercial Nafion membrane.

Example 9 Partially Crosslinked Polymer Electrolyte Membrane Electrode Assembly Preparation

A membrane-electrode assembly for a polymer electrolyte fuel cell was prepared using the partially cross-linked hydrogen ion conductive polymer electrolyte membrane prepared in the above embodiment. In the preparation of the membrane-electrode assembly, platinum-ruthenium (Pt-Ru, Johnson Matthey, HiSPEC 6000) alloy catalyst and platinum black (Pt, Johnson Matthey, HiSPEC 1000) catalyst were used as anode and cathode catalysts, respectively. As the gas diffusion layer, carbon paper (Toray, TGPH-060, 20% PTFE by mass) treated with Teflon was used. After preparing a catalyst ink uniformly dispersed from the catalyst and the partially cross-linked solution for preparing a hydrogen ion conductive polymer electrolyte membrane, it is evenly sprayed onto carbon paper to form a catalyst layer of an anode and an cathode and pressed at a high temperature, thereby A membrane-electrode assembly was prepared.

)막에 대하여, 작동온도 80℃의 동일 운전 조건에서 단위 전지 성능 평가(single cell performance test)를 통하여 성능을 측정한 결과로서, 본 발명의 부분 가교된 고분자 전해질 막의 경우, 전류밀도가 높고, 낮은 전지 전압강하 특성을 나타내므로, 직접 메탄올 연료전지 및 수소이온 교환막 연료전지로 직접 적용이 가능함을 확인하였다. 4 is Nafion-112 compatible with the partially crosslinked polymer electrolyte membrane of the present invention and the polymer electrolyte membrane for uncrosslinked raw materials (Nafion-112).

As a result of measuring the performance of the membrane through the unit cell performance test under the same operating conditions at an operating temperature of 80 ° C, in the case of the partially crosslinked polymer electrolyte membrane of the present invention, the current density was high and low. Since the battery voltage drop characteristics, it was confirmed that the direct methanol fuel cell and the hydrogen ion exchange membrane fuel cell can be directly applied.

)보다 우수한 특성을 나타내었다. 단위 전지 성능면에서는 가교되지 않는 원료용 고분자 전해질 막(실시예 1)의 특성이 오히려 더 우수하였으나,부분 가교화된 고분자 전해질 막(실시예 4)의 경우, 가교로 인한 기계적 물성의 향상 측면에서 장기 안정성이 한층 우수할 것으로 기대된다. 따라서, 본 발명은 부분 가교된 수소이온 전도성 고분자 전해질 막으로 이루어진 막-전극 접합체 및 상기 막-전극 접합체를 채용하는 직접 메탄올 연료전지 및 수소이온 교환막 연료전지를 제공할 수 있다.In addition, in the case of the polymer electrolyte membrane provided by the present invention, both partially crosslinked polymer electrolyte membrane and non-crosslinked polymer electrolyte membrane for raw materials are commonly used Nafion-112.

) Better than). In terms of unit cell performance, the crosslinked polymer electrolyte membrane (Example 1), which is not crosslinked, was more excellent.However, in the case of the partially crosslinked polymer electrolyte membrane (Example 4), the mechanical properties due to crosslinking were improved. Long-term stability is expected to be even better. Accordingly, the present invention can provide a membrane-electrode assembly composed of a partially cross-linked hydrogen ion conductive polymer electrolyte membrane and a direct methanol fuel cell and a hydrogen ion exchange membrane fuel cell employing the membrane-electrode assembly.

As we saw above,

First, the present invention has a mechanical property such that the hydrophilic group exhibiting hydrogen ion conductivity is contained at a high concentration, and the mechanical properties are improved, so that it does not dissolve in boiling water and acid, and does not deform even in the manufacture of thin films having a thickness of 20 μm or less. This superior, hydrocarbon-based hydrogen ion conductive copolymer having an intrinsic viscosity of 2.0 to 3.0 dl / g measured on NMP at 25 ° C. was provided.

Second, by partially crosslinking the bifunctional aromatic vinyl compound to the polymer electrolyte membrane prepared from the hydrocarbon-based hydrogen ion conductive copolymer, while maintaining high ionic conductivity, the partially crosslinked is significantly improved methanol permeability, mechanical properties A method for producing a polymer electrolyte membrane is provided.

)막과 대등하거나 또는 그 이상의 우수한 수소이온 전도성 및 낮은 메탄올 투과도, 향상된 기계적 물성을 구현함으로써, 고분자 전해질형 연료전지에 사용되는 상용된 나피온 막을 대체할 수 있는 고분자 전해질 막을 제공하였다. Third, the partially crosslinked polymer electrolyte membrane of the present invention is commercially available Nafion 112

By providing excellent hydrogen ion conductivity, low methanol permeability, and improved mechanical properties comparable to or higher than that of the membrane, a polymer electrolyte membrane that can replace the commercially available Nafion membrane used in a polymer electrolyte fuel cell was provided.

)보다 우수한 성능 및 효율을 구현할 수 있는 막-전극 접합체 및 이를 채용한 직접 메탄올 연료전지 또는 수소이온 교환막 연료전지를 제공하며, 종래의 고분자 전해질형 연료전지의 전체 효율을 향상시킬 수 있다.Fourth, Nafion 112, which is commercially available for evaluating unit cell performance, using the partially crosslinked polymer electrolyte membrane of the present invention.

The present invention provides a membrane-electrode assembly and a direct methanol fuel cell or a hydrogen ion exchange membrane fuel cell employing the same, and can improve overall efficiency of a conventional polymer electrolyte fuel cell.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and modifications belong to the appended claims.

1 is a ¹ H NMR analysis of the sulfonated polyarylene ether sulfone (SPAES-60) polymer of the present invention,

)막에 대한 이온 전도도를 측정한 결과이고, 2 is Nafion-112 compatible with the partially crosslinked polymer electrolyte membrane of the present invention and the polymer electrolyte membrane for non-crosslinked raw materials (Nafion-112).

Is the result of measuring the ionic conductivity of the membrane,

)막에 대한 기계적 특성 평가 결과이고, 3 is Nafion-112 compatible with the partially crosslinked polymer electrolyte membrane of the present invention and the polymer electrolyte membrane for non-crosslinked raw materials (Nafion-112).

Evaluation results of mechanical properties of the film,

)막에 대한 단위 전지 성능 평가 결과를 나타낸 것이다. 4 is Nafion-112 compatible with the partially crosslinked polymer electrolyte membrane of the present invention and the polymer electrolyte membrane for uncrosslinked raw materials (Nafion-112).

The unit cell performance evaluation results for the membrane are shown.

Claims (9)

Hydrocarbon-based hydrogen ion conductive copolymer, characterized in that the intrinsic viscosity of 2.0 to 3.0 dl / g measured on NMP (N-methyl-α-pyrrolidinone) at 25 ℃ while having a repeating unit represented by the formula (1). Formula 1

(In the above, A and A 'is any one selected from the following functional groups, can be duplicated or cross-selected,

B is any one selected from the following functional groups,

a / (a + b) is 0.001 to 1.0, and c is a degree of polymer polymerization which increases proportionally as the molecular weight of the copolymer increases.) The copolymer according to claim 1, wherein the copolymer is a sulfonated polyarylene ether sulfone copolymer having a sulfonation degree of 55 to 70%. The hydrocarbon-based hydrogen ion conductive copolymer of claim 1 is dissolved in an organic solvent to prepare a solution, cast on a glass or Teflon plate, and then dried to produce a film having a thickness of 30 to 50 μm. Method for producing a polymer electrolyte membrane. A hydrogen ion conductive polymer electrolyte membrane prepared by using the hydrocarbon-based hydrogen ion conductive copolymer represented by Formula 1 prepared from the method of claim 3 is prepared, To prepare a reaction solution containing any one selected from the group of 2-functional aromatic vinyl compound represented by the formula (2), The hydrogen ion conductive polymer electrolyte membrane was immersed in the reaction solution at 80 to 120 ° C. for 1 minute to 12 hours to partially cross-link the bifunctional aromatic vinyl compound to the hydrogen ion conductive polymer electrolyte membrane. After the immersion, a method of producing a partially cross-linked hydrogen ion conductive polymer electrolyte membrane, characterized in that the acid treatment with 0.5M sulfuric acid aqueous solution. Formula 2

The method according to claim 4, wherein the reaction solution is prepared by dissolving 1 to 50% by weight of a 2-functional aromatic vinyl compound in an organic solvent. The organic solvent according to claim 5, wherein the organic solvent is any one selected from the group consisting of methanol, ethanol, isopropanol and butanol when the 2-functional aromatic vinyl compound is a liquid phase, and the 2-functional aromatic vinyl compound is If it is a solid phase, the manufacturing method, characterized in that any one selected from the group of o-xylene, m-xylene and p-xylene. The reaction solution of claim 4, wherein the reaction solution containing the 2-functional aromatic vinyl compound is introduced at 0.01 to 25% by weight per unit mass of the hydrogen ion conductive polymer electrolyte membrane, and is 1 to 100% per unit thickness. Partial crosslinked hydrogen ion conductive polymer electrolyte membrane, characterized in that the thickness of the final crosslinked hydrogen ion conductive polymer electrolyte membrane is 40 to 60 ㎛ to cause an increase in the thickness of. A membrane-electrode assembly made from the partially crosslinked hydrogen ion conductive polymer electrolyte membrane of claim 7. A fuel cell in which the membrane-electrode assembly of claim 8 is employed in a direct methanol fuel cell or a polymer electrolyte fuel cell.

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