KR100535952B1 - Proton-conducting polymer, polymer membrane comprising the polymer, method for maufacturing the same, and fuel cell using the same - Google Patents

Abstract

Proton conductive polymers are disclosed.

The polymer according to the present invention is characterized by having a repeating unit of the following Formula 1.

(One)

The proton conductive polymer membrane according to the present invention is easier to manufacture than the conventional fluorine-based membrane and is very cheap to manufacture, so it is commercially available for a fuel cell for automobiles, and the moisture content is high, so there is no excessive moisture at high current density. The efficiency of the catalyst can be improved, and the fuel cell can be stably operated even at a high temperature of 100 ° C. or higher, thereby preventing poisoning of the catalyst and extending the life of the fuel cell.

Description

Proton-conducting polymer, polymer membrane comprising the polymer, method for maufacturing the same, and fuel cell using the same}

The present invention relates to a proton conductive polymer, and more particularly, to a proton conductive polymer having no water flooding phenomenon, excellent high temperature characteristics, and low manufacturing cost, a method of manufacturing the same, a polymer membrane using the polymer, and a fuel using the same. It relates to a battery.

In recent years, along with environmental problems, exhaustion of energy sources, and the practical use of fuel cell vehicles, development of high-performance fuel cells with high energy efficiency and operation at room temperature and reliability are urgently required. Accordingly, there is also a demand for the development of polymer membranes that can increase the efficiency of fuel cells.

The fuel cell is a new power generation system that converts the energy generated by the electrochemical reaction between fuel gas and oxidant gas directly into electrical energy. It is a molten carbonate electrolyte fuel cell operating at high temperature (500 to 700 ℃), and it operates near 200 ℃. Phosphate electrolyte fuel cells, alkaline electrolyte fuel cells operating at room temperature to about 100 ° C. or less, and polymer electrolyte fuel cells.

On the other hand, the polymer electrolyte fuel cell is a direct methanol fuel cell using a hydrogen ion exchange membrane fuel cell (Proton Exchange Membrane Fuel Cell (PEMFC)) and liquid methanol directly supplied to the anode as a fuel ( Direct Methanol Fuel Cell (DMFC). The polymer electrolyte fuel cell is a future clean energy source that can replace fossil energy, and has high power density and energy conversion efficiency. In addition, since it can operate at room temperature and can be miniaturized and sealed, it can be widely used in fields such as pollution-free automobiles, household power generation systems, mobile communication equipment, medical equipment, military equipment, and space business equipment.

PEMFC is a power generation system for producing direct current electricity from the electrochemical reaction of hydrogen and oxygen, the basic structure of such a cell is shown in FIG.

Referring to FIG. 1, a fuel cell has a structure in which a hydrogen ion exchange membrane 11 is interposed between an anode and a cathode.

The hydrogen ion exchange membrane 11 has a thickness of 50 to 200 μm and is made of a solid polymer electrolyte, and the anode and the cathode are respectively supported by the support layers 14 and 15 for supplying the reactor, and the oxidation / reduction reaction of the reactor. It consists of a gas diffusion electrode (hereinafter referred to collectively referred to as a gas diffusion electrode ") of the catalyst layers 12, 13, which occur. Reference numeral 16 in Fig. 1 has a groove for gas injection. A carbon sheet, which also functions as a current collector.

In the PEMFC having the structure as described above, an oxidation reaction occurs at the anode while hydrogen, which is a reactive gas, is converted into hydrogen ions and electrons. At this time, the hydrogen ions are transferred to the cathode via the hydrogen ion exchange membrane (11). On the other hand, in the cathode, a reduction reaction occurs and oxygen molecules receive electrons and are converted into oxygen ions, and oxygen ions react with hydrogen ions from the anode to be converted into water molecules. As shown in FIG. 1, catalyst layers 12 and 13 are formed on support layers 14 and 15, respectively, in the gas diffusion electrode of PEMFC. At this time, the support layers (14) and (15) are made of carbon cloth or carbon paper, and are surface-treated to facilitate the passage of water and the water generated as a result of the reaction between the reactant and the hydrogen ion exchange membrane (11). In the PEMFC, hydrogen, which is a reactive gas, may be obtained by reforming natural gas or methanol. In this reforming reaction, carbon monoxide is generated, and poisoning of the platinum catalyst of the anode causes a problem of significantly deteriorating cell performance. Therefore, in order to increase the poisoning resistance to the carbon monoxide, it is necessary to allow the cell reaction to occur at a high temperature of 100 ° C or higher.

       On the other hand, PEMFC uses a proton conductive polymer membrane as a hydrogen ion exchange membrane interposed between the anode and the cathode. The polymer used as the polymer membrane has high ionic conductivity, electrochemical safety, mechanical properties as a conductive membrane, and operating temperature. The requirements must be met, such as thermal stability, manufacturability as a thin film to reduce resistance, and low expansion effect when containing liquid. Currently, fluorine-based membranes having a fluorinated alkylene in the main chain and a sulfonic acid group at the terminal of the fluorinated vinyl ether side chain are generally used (for example, manufactured by Nafion and Dupont). However, the fluorine-based membrane has a high manufacturing cost due to the complicated fluorine substitution process, which is difficult to apply to a fuel cell for automobiles, and the moisture content of the fluorine-based membrane is not good. In this case, the water evaporates, the ion conductivity rapidly decreases, the operation of the battery is stopped, and even when operated at a temperature of 100 ° C. or lower, water flooding occurs on the cathode at high current density. There is a problem in that the effective area of is rapidly reduced and the efficiency of the battery is lowered.

Therefore, the first technical problem to be achieved by the present invention is to provide a proton conductive polymer that can be operated at high temperature because the manufacturing cost is low because the sulfonation is easy, and the moisture content of the water is high to reduce the catalyst poisoning phenomenon will be.

The second technical problem to be achieved by the present invention is to provide a proton conductive polymer membrane comprising the proton conductive polymer.

The third technical problem to be achieved by the present invention is to provide a method for producing the proton conductive polymer membrane.

A fourth technical object of the present invention is to provide a fuel cell including the proton conductive polymer membrane.

In order to achieve the first technical problem the present invention

It provides a proton conductive polymer having a repeating unit of the formula (1).

Wherein R ₁ and R ₂ are methyl or trifluoro methyl;

n is an integer from 100 to 100,000)

According to one embodiment of the present invention, the number average molecular weight of the polymer may be 5,000 to 1,000,000.

In addition, the equivalent weight of the polymer is preferably 250 to 2500.

       The present invention to achieve the second technical problem

It provides a proton conductive polymer membrane, characterized in that it is prepared using a polymer having a repeating unit of the formula (1).

According to one embodiment of the present invention, the proton conductive polymer membrane may include 1 to 10 wt% of SiO ₂ based on the total composition.

According to one embodiment of the present invention, the number average molecular weight of the polymer may be 5,000 to 1,000,000.

In addition, the equivalent weight of the polymer is preferably 250 to 2500.

The present invention to achieve the third technical problem,

(a) dissolving decafluorobiphenyl and diphenol derivatives in an organic solvent, adding potassium carbonate (K ₂ CO ₃ ), and then stirring and heating;

(b) cooling the solution and pouring it into an aqueous acetic acid solution to precipitate the polymer;

(c) dissolving the polymer obtained above in an aprotic organic solvent and then sulfonating with addition of a strong acid-giving agent; And

(d) 1 to 10% by weight of a SiO ₂ solution is added dropwise to the solution of the polymer dissolved in acetone, and then uniformly dispersed and the solvent is evaporated to form a membrane.

According to a preferred embodiment of the present invention, the aprotic organic solvent may be chloroform or 1,1,2,2-tetrachloroethane.

In addition, the strong acid-giving agent may be chlorosulfonic acid (chlorosulfonic acid), acetyl sulfonate (acetyl sulfonate) or fuming sulfuric acid (fuming H ₂ SO ₄ ).

According to another embodiment of the present invention, the sulfonation step may adjust the degree of sulfonation (Degree of sulfonation) by controlling the reaction time and the amount of the strong acid-giving agent.

The reaction time of the sulfonation step is preferably 1 hour to 4 hours.

In addition, the molar ratio of the proton conductive polymer and the strong acid group imparting agent in the sulfonation step is preferably 1:10 to 1:30.

The present invention provides a fuel cell, characterized in that produced by employing the proton conductive polymer membrane in order to achieve the fourth technical problem.

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

The base polymer used in the proton conductive polymer membrane according to the present invention has a sulfonic acid group in a poly (fluorinated aromatic ether) polymer chain prepared by nucleophilic substitution reaction of an aryl halide and a diphenol derivative. It is attached structure. In the base polymer, the polymer backbone is thermally and chemically stable and maintains mechanical strength, and sulfonic acid groups serve to move protons. That is, protons are conducted by sulfonic acid groups and their conductivity is further increased by water. The n value of the base polymer repeating unit is preferably 100 to 10,000, and the number average molecular weight is preferably 5,000 to 1,000,000. When the number average molecular weight is less than 5,000, the physical properties of the base polymer are poor. Since it is difficult to dissolve, casting of a polymer film is difficult and undesirable.

In the present specification, the equivalent weight is a numerical value representing the degree of sulfonation in the polymer, and means the average molecular weight of the polymer in which one equivalent of the sulfone group is substituted. Therefore, the smaller this value, the more sulfonated. The equivalent weight can be calculated by dividing the dry weight of the polymer by the concentration of sulfone groups (g / eq), and the concentration of the sulfone groups is obtained by immersing the polymer in 0.1 N sodium hydroxide solution for 12 hours. After using phenolphthalein as indicator, it can be obtained by titration with 0.1 N hydrochloric acid. The equivalent weight is preferably 250 to 2500, and more preferably 400 to 1200. If the equivalent weight is less than 250, it is difficult to form a polymer membrane, and if the equivalent weight is more than 2500, it is difficult to secure ion conductivity. I can't.

Proton conductive polymer membrane according to the present invention prepared by casting the proton conductive polymer is very easy to sulfonate the base polymer, the production cost is low, mass production is possible, by setting the sulfonation degree optimally, The advantage is that the physical properties and the ion conductivity can be optimally adjusted. In addition, the properties of the base polymer constituting the polymer film is easy to control the physical properties by blending with other polymers or by adding other organic and inorganic additives, it is also an advantage that the application range is wide. Examples of the polymer that can be blended with the polymer according to the present invention include polyurethane, polyetherimide, polyetherketone, polyether-ketone, polyurea, polypropylene, polystyrene, polysulfone, polyethersulfone, polyether Ethersulfone, polyphenylenesulfone, polyaramid, polybenzimidazole, poly (bisbenzoxazole-1,4-phenylene), poly (bisbenzo (bis-thiazole) -1,4-phenylene) , Polyphenylene oxide, polyphenylene sulfide, polyparaphenylene, polytrifluorostyrene sulfonic acid, polyvinylphosphonic acid or polystyrene sulfonic acid.

Proton conductive polymer membrane according to the present invention may be a dispersion of 1 to 10% by weight of SiO ₂ uniformly based on the total composition in the base polymer, SiO ₂ is a hydrophilic inorganic material excellent in compatibility with the organic polymer, the base The high reactivity with the hydrophilic channel in the polymer can increase the moisture content of the water. In more detail, SiO ₂ forms SiOH by defects in the hydrophilic portion of the base polymer, which can maintain a moisture content even at a high temperature of 100 ° C. or higher due to the strong hydrogen bonding with water. Poisoning of the electrode catalyst can be reduced. On the other hand, when the content of SiO ₂ is less than 1% by weight, the addition effect thereof is insufficient, and when it exceeds 10% by weight, the brittleness of the polymer film becomes poor, which is not preferable.

Method for producing a proton conductive polymer according to an embodiment of the present invention is as follows.

First, decafluorobiphenyl and a diphenol derivative are polymerized by an addition-elimination reaction as in Scheme 1 below to obtain a poly (fluorinated aromatic ether).

 The diphenol derivative is 4,4- (hexafluoroisopropylidene) diphenol or 4,4-isopropylidene diphenol, and the potassium carbonate is used in excess and acts as a base. First, the benzene ring may be activated due to the fluorine atom bonded to the decafluoro biphenyl, and the addition reaction may occur. In the next step, the removal reaction of the fluorine atom occurs.

Next, a strong acid group imparting agent was added to the matrix polymer as in Scheme 2 to obtain a sulfonated polymer.

Since the poly (fluorinated aromatic ether) is hydrophobic, an aprotic solvent, chloroform or 1,1,2,2-tetrachloroethane, is used as a solvent to dissolve it. The strong acid group imparting agent binds to the aromatic compound of the polymer main chain and imparts an acid group, and consequently, imparts ionic conductivity to the final polymer membrane. As the strong acid-giving agent, chlorosulfonic acid, acetyl sulfonate, fuming H ₂ SO ₄ , etc. may be used, and the sulfonation reaction may be performed using SO ₃ H is substituted by a nucleophilic substitution reaction. The site of the nucleophilic substitution reaction is affected by the kind of substituents attached to the phenyl ring. When the substituents are phenyl ether and methyl groups, they are electron donating groups, which activate the ortho and para positions of the phenyl ring, whereas in the case of trifluoromethyl, they are electron withdrawing groups. Activate meta position of. Thus, sulfonation is made easier when 4,4-isopropylidene diphenol is used than when 4,4- (hexafluoroisopropylidene) diphenol is used as the diphenol derivative.

In the case of Nafion, the sulfonation process is very complicated and the manufacturing cost is high, whereas in the present invention, the sulfonation step is very simple, so the manufacturing cost is reduced and mass production is easy.

In the sulfonation step, the degree of sulfonation may be changed by reaction time, concentration of a strong acid imparting agent, concentration of a reaction polymer, reaction temperature or solvent, and the like in the present invention. The sulfonation degree was adjusted by changing the concentration. As the degree of sulfonation increases, the ion-exchange capacity (IEC) increases because the moisture content of the polymer increases, but it is not preferable because the polymer chain is excessively moistened due to the risk of collapse of the polymer chain. The ion exchange capacity is proportional to the inverse of the aforementioned equivalent weight.

It is preferable that the reaction time of the sulfonation step is 1 hour to 4 hours. If the sulfonation is less than 1 hour, since the sulfonation is not sufficient, the ion conductivity is insufficient and the process efficiency is lowered when it exceeds 4 hours. On the other hand, the molar ratio of the polymer and fuming sulfuric acid is preferably from 1:10 to 1:30. When the molecular weight is less than 1:10, since the sulfonation degree is not sufficient, the ionic conductivity is not high. It is not preferable because there is a risk of becoming poor.

The proton conductive polymer membrane according to the present invention is prepared by dissolving the polymer obtained above or the polymer blend containing the polymer in a solvent, mixing with a SiO ₂ solution, and then forming a membrane having a desired thickness using a solution casting method or a heat compression method. The thickness of the polymer film is preferably in the range of 5 to 200 µm.

The fuel cell according to the present invention can be manufactured by a conventional manufacturing method of forming a single cell by placing the proton conductive polymer membrane prepared above between the cathode and the anode.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited thereto.

Example 1

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

17.05 g of decafloobiphenyl, 17.16 g of 4,4- (hexafluoroisopropylidene) diphenol and 350 mL of anhydrous N, N-dimethylacetamide (manufactured by Aldrich) were added to a three-necked round bottom flask equipped with nitrogen. Stirring gave a clear solution. Next, potassium carbonate (manufactured by Junsei Chemical Co., Ltd.) was added in excess, and then the temperature of the mixed solution was raised to 120 ° C. and reacted for 2 hours. After the reaction, the solution was put in 1% acetic acid aqueous solution to obtain a white precipitate. The precipitate obtained above was washed several times with distilled water and then dried in a vacuum oven for 24 hours to obtain a white polymer powder. 2.0 g of the polymer powder obtained above was placed in a flask containing 198 mL of chloroform, and then the solution was stirred to obtain a clear solution. 98% fuming sulfuric acid was slowly added dropwise to the solution at a ratio of 1:10 (polymer: fuel sulfuric acid) by molar ratio, followed by stirring for 2 hours. The solution was slowly added to excess distilled water to give a white precipitate which was then evaporated chloroform and washed several times with distilled water until the pH reached 7, followed by drying in a vacuum oven for 24 hours to give a sulfonated poly (fluorinated aromatic ether: SDF-F). The following NMR data is for poly (fluorinated aromatic ether) before sulfonation, but only the data before sulfonation are attached since the peak becomes very complex and the peak assignment becomes difficult after sulfonation. However, when sulfonation is performed, it shifts toward the downfield from the peak before sulfonation.

Weight average molecular weight: 4.33 x 10 ⁵ , Number average molecular weight: 1.83 x 10 ⁴

¹ H-NMR (CD ₃ COCD ₃ ): δ 7.337 to 7.367 (d, 4H, Ar- H ), 7.483 to 7.510 (d, 4H, Ar- H )

¹⁹ F-NMR (CD ₃ COCD ₃ ): δ-150.618 to -150.569, -135.157 to -135.080, -60.30

Example 2

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

Sulfonated poly (fluorinated aromatic ether: SDF-F) was prepared in the same manner as in Example 1, except that the molar ratio of the polymer and fuming sulfuric acid was 1:20.

Example 3

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

Sulfonated poly (fluorinated aromatic ether: SDF-F) was prepared in the same manner as in Example 1, except that the molar ratio of the polymer and fuming sulfuric acid was 1:30.

Example 4

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

A sulfonated poly (fluorinated aromatic ether: SDF-F) was prepared in the same manner as in Example 2, except that the reaction time of the polymer and fuming sulfuric acid was 1 hour.

Example 5

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

A sulfonated poly (fluorinated aromatic ether: SDF-F) was prepared in the same manner as in Example 2, except that the reaction time of the polymer and the fuming sulfuric acid was 1 hour 30 minutes.

Example 6

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

A sulfonated poly (fluorinated aromatic ether: SDF-F) was prepared in the same manner as in Example 2, except that the reaction time of the polymer and fuming sulfuric acid was 3 hours.

Example 7

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

A sulfonated poly (fluorinated aromatic ether: SDF-F) was prepared in the same manner as in Example 2, except that the reaction time of the polymer and fuming sulfuric acid was 4 hours.

Example 8

Preparation of Poly (Fluorinated Aromatic Ether) Having Sulphonic Acid Groups

Poly (fluorinated aromatic ether) sulfonated in the same manner as in Example 2, except that 2.0 g of 4,4-isopropylidene diphenol was used instead of 4,4- (hexafluoroisopropylidene) diphenol: SDF-H) was obtained, followed by NMR data for poly (fluorinated aromatic ether) prior to sulfonation.

Weight average molecular weight: 1.25 x 10 ⁵ , Number average molecular weight: 1.82 x 10 ⁴

¹ H-NMR (CDCl ₂ CDCl ₂ ): δ 1.572 (s, 6H, C H ₃ ), 6.850-6.878 (d, 4H, Ar- H ), 7.103-7.131 (d, 4H, Ar- H )

¹⁹ F-NMR (CDCl ₂ CDCl ₂ ): δ -150.988 to -150.939, -135.634 to -135.547

Example 9

Preparation of Proton Conductive Polymer Membrane

A transparent solution obtained by dissolving 1.0 g of the white powder obtained in Example 2 in acetone was film cast and then dried in a vacuum oven at 70 ° C. to prepare a proton conductive polymer membrane.

Examples 10-16

Preparation of Proton Conductive Polymer Membrane

First, 2 ml of TEOS (tetraethyl orthosilicate) solution, 4.7 ml of distilled water and 100 ml of 0.1 M HCl were added to a Erlenmeyer flask and stirred at room temperature for 3 hours to prepare a SiO ₂ solution. Meanwhile, 1 g of the sulfonated base polymer prepared in Examples 1 to 7 was dried in a vacuum oven for 24 hours, and then dissolved in 20 g of acetone. The mixed solution was prepared by dropwise adding the SiO ₂ solution in an amount corresponding to 4% by mass to the prepared polymer solution. The solution thus prepared was placed in a Teflon dish and dried at room temperature for 24 hours to prepare a proton conductive polymer membrane mixed with 4 wt% of SiO ₂ .

Example 17

Preparation of Proton Conductive Polymer Membrane

A proton conductive polymer membrane was prepared in the same manner as in Example 10, except that 1 g of the sulfonated base polymer prepared in Example 8 was dissolved in a chloroform: ethanol (3: 7) mixed solvent.

Comparative Example 1

Nafion 117 (manufactured by DuPont) was added to a 30 vol.% H ₂ O ₂ solution and heated to remove organic substances from the surface. Then, it was added to 0.5 M sulfuric acid and heated for 1 hour to replace Na ⁺ with H ⁺ and washed with water. A proton conductive polymer membrane was prepared.

Examples 18-19 and Comparative Example 2

Manufacture of Fuel Cells

Between the electrodes doped with carbon catalyst 20% of platinum (manufactured by Bon Enterprises Inc.), the proton conductive polymer membranes prepared in Examples 9, 11 and Comparative Example 1 were placed, and hot pressing was performed at 100 ° C and 15 atm. A membrane electrode assembly (MEA) was prepared by bonding using.

Test Example 1

Measurement of Hygroscopicity and Ionic Conductivity of Proton Conductive Polymer Membranes

The proton conductive polymers prepared in Examples 9 to 17 and Comparative Example 1 were immersed in water, and then the hygroscopicity was measured by checking the weight change, and the ion conductivity was measured by impedance analyzer (impedance analyzer: Zahner elektrik: IM6). After obtaining the bulk resistance by the Nyquist plot by was measured using the following equation 1, the results are shown in Table 1 below.

                (a: thickness of film d: radius of electrode

σ: ion conductivity, R _b : bulk resistance)

Hygroscopicity (%) Ion Conductivity (Scm ^-1 ) Example 9 89.16 1.05 x 10 ^-3 Example 10 193.18 2.12 x 10 ^-3 Example 11 201.33 3.94 x 10 ^-3 Example 12 210.29 4.03 x 10 ^-3 Example 13 30.08 1.22 x 10 ^-4 Example 14 56.34 6.92 x 10 ^-4 Example 15 94.23 1.13 x 10 ^-3 Example 16 98.69 1.17 x 10 ^-3 Example 17 834.68 1.33 x 10 ^-2 Comparative Example 1 28.51 2.95 x 10 ^-2

As can be seen in Table 1, the proton-conducting polymer according to the present invention has a slightly lower or similar ionic conductivity than the conventional fluorine-based proton-conducting polymer, but has excellent hygroscopicity. Therefore, even at high current densities, there is no overwater phenomenon, thereby improving efficiency and power density of the battery, and in particular, since it can be operated at a high temperature, it is possible to extend the life of the battery by preventing poisoning of the catalyst.

Test Example 2

Observation by EPMA

Electron probe microanalyzer (EPMA, JXA-8600 manufactured by JEOL, Inc.)-Si mapping to confirm the distribution of the elements of the proton conductive polymer membranes prepared in Examples 9 and 11 and shown in FIG. As shown in Fig. 2 (b), it can be seen that in accordance with the present invention the film is SiO ₂ SiO ₂ is incorporated proton conductive polymer are uniformly distributed, the polymer according to the present invention is excellent in compatibility of SiO ₂ You can see that.

Test Example 3

Thermal Stability Measurement of Proton Conductive Polymer Membranes

The temperature at which the structures of the proton conductive polymer membranes prepared in Examples 9 and 11 were decomposed while raising the temperature using a Dupont thermogravimetric analyzer (TGA) 2050 was confirmed as a decrease in mass, and the results are shown in FIGS. 3 and 4. 3 is a result of the proton conductive polymer membrane prepared in Example 9, it can be seen that the -SO ₃ H group is decomposed at 324.5 ℃ and the polymer main chain is decomposed at 573.2 ℃ is stable even at high temperatures. In addition, referring to FIG. 4, which is a result of the proton conductive polymer membrane prepared in Example 11, the temperature at which the -SO ₃ H group is decomposed is 343.7 ° C., and the temperature at which the polymer main chain is decomposed is 641 ° C., which further increases thermal stability. It can be seen that. It is thought that this is because when SiO ₂ is mixed, the SiO ₂ is bonded to the hydrophilic portion of the proton conductive polymer to form SiOH, which causes strong hydrogen bonding with water, thereby increasing thermal stability.

Test Example 4

Fuel cell test

Cell tests were carried out on the fuel cells prepared in Examples 18, 19 and Comparative Example 2, and oxygen gas was injected to the anode side, and hydrogen gas was injected to the cathode side, and the injection speed was 300 cc / min. At this time, the respective gases are passed through the humidifier so that the fuel is not dried and the temperature of the cathode, anode, and cell can be individually controlled using a thyristor power regulator (TPR). In order to obtain data about current and voltage, an opposite current is applied to obtain a constant resistance in OCV (Open Circuit Voltage), and each value of current density vs. power density, current density vs. voltage, current vs. power density is measured. It measured, and the result is shown to FIGS.

FIG. 5 shows a current density-power density curve when the fuel cell prepared in Example 18 and Comparative Example 2 is operated at 80 ° C., and its operating temperature is cathode / cell / anode for both line heater and humidifier = 85 ° C. FIG. / 80 ° C / 90 ° C and the pressure was 1 atmosphere. Referring to the drawings, the fuel cell according to the present invention has a similar or slightly lower power density than the case of the comparative example at a low current density, but the fuel cell according to the present invention is higher than the case of the comparative example at a high current density region of 1000 mA / cm ² or more. It shows the power density and the performance is excellent.

FIG. 6 shows a current density-voltage curve when operating the fuel cell prepared in Example 19 and Comparative Example 2 at 80 ° C, and the operating temperature is cathode / cell / anode of line heater and humidifier = 85 ° C. / 80 ° C / 90 ° C and the pressure was 1 atmosphere. In the high current density region of 1000 mA / cm ² or more, it can be seen that the fuel cell according to the present invention exhibits a higher voltage than the comparative example and has excellent performance. This is because the proton-conducting polymer according to the present invention has good hygroscopicity, so that no excessive moisture occurs even at high current density.

7 shows an initial current-power density curve when the fuel cell manufactured by Example 19 and Comparative Example 2 of the present invention is operated at a temperature of 110 ° C., and the operating temperature is a cathode of both the line heater and the humidifier. / Cell / anode = 108 占 폚 / 110 占 폚 / 108 占 폚 and pressure was 2 atm. In the case of Comparative Example 2, the data on the power density is not shown at 1.5A or more because the voltage is very low as 0.4V or less above the current, but the measurement error is large, and thus the measurement of the value is difficult. 8 shows a current-power density curve after operating the fuel cell manufactured in Example 19 and Comparative Example 2 at 110 ° C. for 16 hours. In FIG. 8, in the case of Comparative Example 2, the data for the power density is not shown at a current of 1.0 A or more, because the measurement was difficult because the voltage showed a very low value below the reference value. Referring to FIGS. 7 and 8, when operating at 110 ° C., the performance of the fuel cell according to the present invention was initially about the same as that of the fuel cell manufactured by Comparative Example 2, but after 16 hours, It can be seen that the power density and performance of the fuel cell according to the present invention are much better than those of the comparative example. In particular, in the case of Comparative Example 2 in FIG. 8, the power density does not exceed 0.40W, while in Example 19, the power density may be 0.70W or more at high current, which is excellent in the hygroscopicity of the polymer membrane according to the present invention. Because.

9 shows a current density-voltage curve when the fuel cell using the polymer membranes prepared by Example 19 and Comparative Example 2 at 120 ° C., in which case the operating temperature is the cathode / cell / Anode = 113 ° C./120° C./1130° C., and the pressure was 2.5 atmospheres. In the case of Comparative Example 2, the voltage suddenly decreases, so that the battery does not operate at 500 mA / cm ² or more. However, according to the present invention, excellent performance is maintained up to a high current density region of 1000 mA / cm ² or more even at an operating temperature of 120 ° C. Therefore, the high temperature performance is very excellent, the poisoning phenomenon of the catalyst can be suppressed, and the battery life can be extended.

The proton conductive polymer membrane according to the present invention is easier to manufacture than the conventional fluorine-based membrane and is very cheap to manufacture, so it is commercially available for a fuel cell for automobiles, and the moisture content is high, so there is no excessive moisture at high current density. The efficiency of the catalyst can be improved, and the fuel cell can be stably operated even at a high temperature of 100 ° C. or higher, thereby preventing poisoning of the catalyst and extending the life of the fuel cell.

1 shows the structure of a typical hydrogen ion exchange membrane fuel cell.

FIG. 2 (a) is a diagram illustrating the distribution of elements of the proton conductive polymer membrane prepared in Example 9 through EPMA-Si mapping.

FIG. 2 (b) is a diagram illustrating the distribution of elements of the proton conductive polymer membrane prepared in Example 11 through EPMA-Si mapping.

3 is a graph measuring the temperature at which the structure of the proton conductive polymer prepared in Example 9 is degraded using TGA.

Figure 4 is a graph measuring the temperature at which the structure of the proton conductive polymer prepared in Example 11 decomposes using TGA.

FIG. 5 shows current-power density curves when the fuel cell produced by Example 18 and Comparative Example 2 is operated at 80 ° C.

FIG. 6 shows current density-voltage curves when the fuel cell produced by Example 19 and Comparative Example 2 is operated at 80 ° C.

FIG. 7 shows an initial current-power density curve when the fuel cell manufactured by Example 19 and Comparative Example 2 is operated at 110 ° C.

FIG. 8 shows a current-power density curve after operating the fuel cell prepared in Example 19 and Comparative Example 2 at 110 ° C. for 16 hours.

FIG. 9 shows current density-voltage curves when the fuel cell cells prepared in Example 19 and Comparative Example 2 were operated at 120 ° C.

<Explanation of symbols for main parts of the drawings>

11 hydrogen ion exchange membrane 12 anode catalyst layer

13 ... cathode catalyst layer 14 ... anode support layer

15 ... cathode support layer 16 ... carbon plate

Claims (14)

Proton conductive polymer having a repeating unit of the following formula 1. (One) Wherein R ₁ and R ₂ are methyl or trifluoro methyl; n is an integer from 100 to 100,000) The proton conductive polymer according to claim 1, wherein the polymer has a number average molecular weight of 5,000 to 1,000,000. The proton conductive polymer according to claim 1, wherein the equivalent weight of the polymer is 250 to 2500. Proton conductive polymer membrane, characterized in that produced using the proton conductive polymer according to claim 1. 5. The proton conductive polymer membrane according to claim 4, further comprising 1 to 10% by weight of SiO ₂ based on the total composition. The proton conductive polymer membrane according to claim 4, wherein the polymer has a number average molecular weight of 5,000 to 1,000,000. 5. The proton conductive polymer membrane according to claim 4, wherein the equivalent weight of the polymer is 250 to 2500. (a) dissolving decafluorobiphenyl and diphenol derivatives in an organic solvent, adding potassium carbonate (K ₂ CO ₃ ), and then stirring and heating; (b) cooling the solution and pouring it into an aqueous acetic acid solution to precipitate the polymer; (c) dissolving the polymer obtained above in an aprotic organic solvent and then sulfonating with addition of a strong acid-giving agent; And (d) adding 1-10% by weight of a solution of SiO ₂ to a solution in which the polymer is dissolved in acetone, and then uniformly dispersing and evaporating the solvent to form a membrane. The method of claim 8, wherein the aprotic organic solvent is chloroform or 1,1,2,2-tetrachloroethane. The method of claim 8, wherein the strong acid-providing agent is chlorosulfonic acid, acetyl sulfonate, or fuming H ₂ SO ₄ . The method of claim 8, wherein the sulfonation step controls a degree of sulfonation by controlling a reaction time and an amount of a strong acid-giving agent.       The method according to claim 8, wherein the reaction time of the sulfonation step is 1 hour to 4 hours.       The method of claim 8, wherein the molar ratio of the proton-conducting polymer and the strong acid-giving agent in the sulfonation step is 1:10 to 1:30. A fuel cell manufactured by employing the proton conductive polymer membrane according to any one of claims 4 to 7.