Sulfonic acid group-containing polymer having novel structure, cation exchange membrane, manufacturing method thereof, and water electrolysis systems using same

Abstract

The present invention relates to: a sulfonic acid group-containing polymer having a novel structure; a cation exchange membrane; a manufacturing method thereof; and water electrolysis systems using same. More specifically, the present invention relates to: a polymer having a branched structure; and a cation exchange membrane and water electrolysis systems in which the polymer is used to promote a microphase-separated structure, wherein rather than developing a cation exchange material through conventional condensation polymerization in the presence of a basic catalyst, structural design is carried out using an electrophilic substitution reaction under strongly acidic conditions such that the main chain of the polymer does not contain any chemically weak bonds (e.g., ether bond), and various ion exchange functional groups can only be introduced at the side chain ends of the polymer.

Description

Polymer having a sulfonic acid group of a novel structure and cation exchange membrane, method for manufacturing the same and water electrolysis system using the same

[0001] The present invention relates to a polymer having a sulfonic acid group of a novel structure, a cation exchange membrane, a method for manufacturing the same, and a water electrolysis system using the same.

[0002]

[0003] Currently, 99% of global hydrogen production is derived from fossil fuels, resulting in the emission of carbon dioxide. Consequently, a transition to carbon-free green hydrogen production technologies is essential to achieve carbon neutrality. The water electrolysis method is the most ideal model, as it mass-produces hydrogen from water and utilizes renewable electricity from sources such as solar and wind power, making the entire production process environmentally friendly.

[0004] Water electrolysis using a polymer electrolyte membrane, one of the hydrogen production methods, is a device that electrochemically decomposes water to produce hydrogen and oxygen. It is a technology attracting attention because, compared to other hydrogen production methods, it has the advantages of simple operating conditions, a small volume, and the ability to obtain high-purity hydrogen. It can also be used in hydrogen fuel cells. Hydrogen fuel cells are a method of producing electricity by electrochemically reacting hydrogen and oxygen as the reverse reaction of water electrolysis; they are considered an alternative energy technology because they are more environmentally friendly and have higher fuel efficiency compared to internal combustion engines.

[0005] Proton Exchange Membranes (PEMs), which are core materials used in various energy conversion and storage devices including water electrolysis and fuel cell systems, serve as electrolytes and separators that selectively transport only hydrogen ions. Therefore, due to the characteristics of water electrolysis systems operated under water-based / pressurized conditions, the PEMs utilized in these systems require characteristics such as 1) high ion conductivity, 2) outstanding physicochemical stability, 3) ease to scalable mass production, and 4) low cost for production.

[0006] Currently, the most widely used PEMs are Kemmers’ perfluorinated electrolyte Nafion® and Gore’s perfluorinated porous packed membrane Gore-Select®. Both are utilized in most commercial or commissioning fuel cells, oxidation / reduction flow cells, and electrochemical hydrogen compressor systems due to their high ionic conductivity and chemical stability. However, all existing perfluorinated PEMs have disadvantages such as 1) decomposition by oxygen radicals, 2) environmental pollution caused by hydrofluoric acid and contaminants during incineration, and 3) high unit costs due to complex manufacturing processes. Furthermore, when applied as electrolyte membranes for water electrolysis, there are concerns that 1) operating conditions may be restricted due to high gas permeability characteristics, and 2) physicochemical properties may deteriorate due to low glass transition temperatures. Accordingly, there is a need to develop hydrocarbon-based polymer electrolyte membranes that have excellent ionic conductivity and physicochemical properties and are easy to utilize as membrane electrode assemblies for water electrolysis.

[0007] There is a need to develop a non-perfluorocarbon branched polymer electrolyte membrane that has excellent ionic conductivity and mechanical strength and is easy to utilize as a membrane electrode assembly for polymer electrolyte membrane water electrolysis.

[0008] Therefore, in order to develop an electrolyte membrane applicable in a water electrolysis system that satisfies all the required characteristics for the preparation of additives for hydrogen ion exchange membranes described above, it is required to 1) have an easy introduction of ion exchange functional groups, 2) have branched side chains based on carbon-carbon bonds with excellent chemical stability, 3) have lower crystallinity and increased solubility due to increased free volume between polymer chains caused by carbazole, 4) have low gas permeability for system stability, and 5) have excellent physical stability that can withstand high temperature and high pressure.

[0009]

[0010] The present invention has been devised to solve the above-mentioned problems, and the objective of the present invention is to provide a polymer with a branched structure that is easy to modify at the end of the side chain, having a fluorine-free, fully hydrocarbon-based main chain and side chains, by utilizing an electrophilic substitution reaction under strong acid conditions rather than the development of electrolyte materials through condensation polymerization under conventional basic catalysts.

[0011] In addition, the present invention provides a hydrocarbon-based cation exchange membrane using the above-mentioned polymer, which ensures excellent hydrogen ion conductivity and physicochemical stability, and a water electrolysis system using the same.

[0012] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0013]

[0014] To achieve the above objective, the present invention provides a polymer represented by the following [Chemical Formula 1].

[0015] [Chemical Formula 1]

[0016]

[0017] In the above chemical formula 1,

[0018] The range of n is 0 to 1, and

[0019] m and z comprise hydrogen or an alkyl group having 1 to 10 carbon atoms, and

[0020] R1 and R2 are hydrogen, , or is,

[0021] X is , , or is,

[0022] Is or It is characterized by being.

[0023] The weight average molecular weight (Mw) of the above polymer may be 10,000 to 1,000,000 g / mol.

[0024] In addition, the present invention provides a cation exchange membrane comprising the above-mentioned polymer.

[0025] In addition, the present invention provides a method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by comprising: a first step of mixing and reacting diphenylcarbazole and 1,1,1-trifluoroacetone; a second step of mixing and reacting the polymer synthesized in the first step with sodium 3-bromopropane-1-sulfonate; a third step of dissolving the polymer synthesized in the second step in dimethylsulfoxide (DMSO), then casting and drying in a drying oven to produce a membrane; and a fourth step of immersing the membrane produced in the third step in an aqueous sulfuric acid solution to substitute the functional group terminals of the membrane produced with sulfonic acid groups.

[0026] In the first step above, 1 to 2 moles of 1,1,1-trifluoroacetone may be mixed with 1 mole of diphenylcarbazole.

[0027] The first step above may use trifluoromethanesulfonic acid (TFSA) as a catalyst and dichloromethane (DCM) as a reaction solvent.

[0028] The first step above may involve mixing the diphenylcarbazole and 1,1,1-trifluoroacetone, maintaining the mixture at 1 to 10°C for 5 to 20 minutes, and then reacting it at room temperature for 1 to 5 hours.

[0029] The second step above uses sodium hydroxide (NaOH) as a catalyst and may use dimethyl sulfoxide (DMSO) as a reaction solvent.

[0030] The second step above may involve mixing 2 to 5 moles of sodium 3-bromopropane-1-sulfonate with respect to 1 mole of the polymer synthesized in the first step.

[0031] The second step above may involve mixing the polymer synthesized in the first step with sodium 3-bromopropane-1-sulfonate and reacting at 40 to 60°C for 15 to 25 hours.

[0032] The third step above can be performed by dissolving the polymer synthesized in the second step in dimethylsulfoxide (DMSO), and then, after casting, drying it in a drying oven at 65 to 85 ℃ for 5 to 10 hours to produce a membrane.

[0033] The above fourth step may involve placing the membrane prepared in the above third step into an aqueous sulfuric acid solution and immersing it at 50 to 70°C for 10 to 15 hours.

[0034] In addition, the present invention provides a water electrolysis system comprising the above-mentioned cation exchange membrane.

[0035]

[0036] By means of solving the above problem, the present invention utilizes electrophilic substitution reactions under strong acid conditions, rather than conventional development of electrolyte materials through condensation polymerization under basic catalysts, to design a structure in which chemically weak bonds are not present in the polymer main chain, and can provide a polymer with a branched structure in which various ion exchange functional groups can be introduced only at the ends of the polymer side chains.

[0037] In addition, the present invention can simultaneously improve ion conduction behavior and physicochemical stability due to a distinct hydrophilic / hydrophobic phase separation effect by synthesizing a branched polymer precursor capable of having hydrophilic functional groups to promote a hydrophilic / hydrophobic microphase separation structure.

[0038] In addition, by using the polymer according to the present invention, the hydrophilic / hydrophobic phase separation effect can be maximized due to the dense hydrophilic functional groups, and at the same time, a cation exchange membrane capable of controlling the ion conduction channel structure according to the application can be provided.

[0039] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0040]

[0041] Figure 1 shows the structure of a polymer having a novel sulfonic acid group structure prepared according to the present invention.

[0042] Figure 2 shows a schematic diagram of the synthesis of a polymer (PCA3SA-100) synthesized in one embodiment of the present invention.

[0043] FIG. 3 is of PCAC3-100 and PCA3SA-100 synthesized in an embodiment of the present invention. 1 This shows the results of the H NMR analysis.

[0044] Figure 4 shows the FT-IR spectra of PCAC3-100 and PCA3SA-100 synthesized in one embodiment of the present invention.

[0045] Figure 5 shows the TGA analysis results of PCAC3-100 and PCA3SA-100 synthesized in one embodiment of the present invention.

[0046] Figure 6 shows a PCA3SA-100 cation exchange membrane manufactured in one embodiment of the present invention.

[0047] Figure 7 shows the strain-stress curve of a PCA3SA-100 cation exchange membrane prepared in one embodiment of the present invention.

[0048] Figure 8 shows the hydrogen ion conductivity of the PCA3SA-100 cation exchange membrane according to temperature change.

[0049]

[0050] The terms used in this invention have been selected based on currently widely used general terms, taking into account their functions within the invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention.

[0051] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0052] When a part of a specification is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0053] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0054]

[0055] The present invention will be described in detail below.

[0056]

[0057] The present invention provides a polymer represented by the following [Chemical Formula 1].

[0058] [Chemical Formula 1]

[0059]

[0060] In the above chemical formula 1,

[0061] The range of n is 0 to 1, and

[0062] m and z comprise hydrogen or an alkyl group having 1 to 10 carbon atoms, and

[0063] R1 and R2 are hydrogen, , or is,

[0064] X is , , or is,

[0065] Is or It is characterized by being.

[0066] The weight average molecular weight (Mw) of the above polymer may be 10,000 to 1,000,000 g / mol.

[0067] The above polymer has excellent chemical stability as its polymer backchain consists solely of carbon-carbon bonds. aryl ether bonds (C) in polymers used in proton exchange membranes (PEMs). sp2 If bonds with low bond energy (benzylic CH bonds) or bonds with low bond energy (-O) are present, the polymer may decompose under various operating conditions in which cation exchange membranes are utilized. The polymer according to the present invention is synthesized as a polymer based on carbon-carbon bonds that do not contain weak bonds capable of decomposition, and thus possesses excellent chemical stability.

[0068] The above polymer is configured with a flexible and long alkyl structure in the branch portion of the branched polymer to promote a hydrophilic and hydrophobic microphase separation structure, and has a modifiable site at the branch end, which further promotes the hydrophilic and hydrophobic microphase separation and can form a wide ion conduction channel.

[0069] The above polymer may have lower crystallinity and higher solubility due to the increased free volume between polymer chains caused by the bent structure of the main chain composed of carbazole.

[0070] In addition, the present invention provides a cation exchange membrane comprising the above-mentioned polymer.

[0071] The above cation exchange membrane is a carbon bond-based polymer electrolyte membrane, and compared to commercially available perfluorinated polymer electrolyte membranes, it exhibits low gas permeability, which can increase stability.

[0072] In addition, the present invention provides a method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by comprising: a first step of mixing and reacting diphenylcarbazole and 1,1,1-trifluoroacetone; a second step of mixing and reacting the polymer synthesized in the first step with sodium 3-bromopropane-1-sulfonate; a third step of dissolving the polymer synthesized in the second step in dimethylsulfoxide (DMSO), then casting and drying in a drying oven to produce a membrane; and a fourth step of immersing the membrane produced in the third step in an aqueous sulfuric acid solution to substitute the functional group terminals of the membrane produced with sulfonic acid groups.

[0073] Figure 2 shows a schematic diagram of the synthesis of a polymer and a cation exchange membrane according to an embodiment of the present invention.

[0074] In the first step above, 1 to 2 moles of 1,1,1-trifluoroacetone may be mixed with 1 mole of diphenylcarbazole. Preferably, 1 to 1.5 moles of 1,1,1-trifluoroacetone may be mixed with 1 mole of diphenylcarbazole, but are not limited thereto.

[0075] The first step above may use trifluoromethanesulfonic acid (TFSA) as a catalyst and dichloromethane (DCM) as a reaction solvent.

[0076] The first step above may involve mixing the diphenylcarbazole and 1,1,1-trifluoroacetone and maintaining the mixture at 1 to 10°C for 5 to 20 minutes, followed by a reaction at room temperature for 1 to 5 hours. Preferably, the mixture may be maintained at 3 to 7°C for 8 to 12 minutes, followed by a reaction at room temperature for 2 to 4 hours, but is not limited thereto.

[0077] After the first step above, the method may further include the step of precipitating the polymer solution produced in the first step in methanol, washing it several times with methanol, and then drying it in a vacuum oven at 35 to 45°C. Preferably, it may be dried in a vacuum oven at 40°C, but is not limited thereto.

[0078] The second step above uses sodium hydroxide (NaOH) as a catalyst and may use dimethyl sulfoxide (DMSO) as a reaction solvent.

[0079] In the second step, 2 to 5 moles of sodium 3-bromopropane-1-sulfonate may be mixed with 1 mole of the polymer synthesized in the first step. Preferably, 2 to 4 moles of sodium 3-bromopropane-1-sulfonate may be mixed with 1 mole of the polymer synthesized in the first step, but are not limited thereto.

[0080] The second step above may involve mixing the polymer synthesized in the first step with sodium 3-bromopropane-1-sulfonate and reacting at 40 to 60°C for 15 to 25 hours. Preferably, the reaction may be carried out at 45 to 55°C for 15 to 20 hours, but is not limited thereto.

[0081] After the second step above, the method may further include a step of precipitating the polymer solution produced in the second step in acetone, washing it several times with methanol, and then drying it in a vacuum oven at 35 to 45°C. Preferably, it may be dried in a vacuum oven at 40°C, but is not limited thereto.

[0082] In the third step above, the polymer synthesized in the second step can be dissolved in dimethylsulfoxide (DMSO), and then, after casting, dried in a drying oven at 65 to 85 ℃ for 5 to 10 hours to produce a membrane. Preferably, the membrane can be produced by drying at 70 to 80 ℃ for 7 to 9 hours, but is not limited thereto.

[0083] In the fourth step above, the membrane prepared in the third step may be placed in an aqueous sulfuric acid solution and immersed at 50 to 70°C for 10 to 15 hours. Preferably, it may be immersed at 55 to 60°C for 11 to 13 hours, but is not limited thereto.

[0084] After the above fourth step, the method may further include a step of washing the manufactured membrane with distilled water and drying it at room temperature.

[0085] In addition, the present invention provides a water electrolysis system comprising the above-mentioned cation exchange membrane.

[0086]

[0087] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0088]

[0089] <Example 1> Preparation of a cation exchange membrane having a sulfonic acid group (-SO3H)

[0090] 1. Diphenylcarbazole-based polymer (PCAC3-100) synthesis

[0091] PCA4C3-100 was synthesized by reacting diphenylcarbazole (2.06 g, 6.45 mmol) and 1,1,1-trifluoroacetone (0.87 g, 7.74 mmol) as monomers, trifluoromethanesulfonic acid (TFSA) (9.68 g, 64.49 mmol) as a catalyst, and 40 wt% dichloromethane (DCM) relative to the monomer weight as the reaction solvent, maintaining the temperature at 5°C for 10 m and then at RT for 3 h. After the reaction, the resulting polymer solution was precipitated in methanol (1300 ml), washed several times with methanol, and then dried in a vacuum oven at 40°C.

[0092] 2. Diphenylcarbazole-based graft polymer with sodium sulphate group (PCA3SA-100(Na + form)) synthesis

[0093] PCA3SA-100 was synthesized by reacting previously synthesized PCAC3-100 (1.5 g, 3.63 mmol) and sodium 3-bromopropane-1-sulfonate (2.45 g, 10.88 mmol) as reactants, and sodium hydroxide (0.36 g, 9.07 mmol) as a catalyst, at 50 °C for 18 hours. 4.5 wt% dimethylsulfoxide (DMSO) was used as the reaction solvent. After the reaction, the resulting polymer solution was precipitated in acetone (1000 ml), washed several times with distilled water, and then dried in a vacuum oven at 40 °C.

[0094]

[0095] 3. Preparation of a cation exchange membrane having a sulfonic acid group (-SO3H)

[0096] 0.3 g of the above-prepared PCA3SA-100 was dissolved in 13 wt% DMSO by weight, cast onto a borosilicate plate, and dried in a drying oven at 75 ℃ for 8 hours to prepare a membrane. Then, the membrane was placed in a 1 M aqueous sulfuric acid solution and maintained at 60 ℃ for 12 hours to substitute the terminal functional groups with sulfonic acid groups. Afterward, the membrane was washed several times with distilled water and dried at room temperature to prepare a cation exchange membrane.

[0097]

[0098] <Experimental Example 1> PCAC3-100, Post_PCA3SA-100 of 1 H NMR

[0099] To confirm the synthesis of PCAC3-100 and Post_PCA3SA-100 1 1H NMR was measured and is shown in Fig. 3. Referring to Fig. 3, PCAC3-100's 1 As a result of H NMR analysis, a phenyl peak of the polymer main chain can be observed between 7.0 and 8.0 ppm, and an NH peak can be observed at 11.5 ppm.

[0100] In the case of PCA3SA-100, it can be confirmed that the alkyl group peak of the side chain is generated between 1.5 and 5.0 ppm due to the introduction of functional groups. As a result, the NH(1) peak that appeared at 11.5 ppm in PCAC3-100 completely disappeared, and it was also confirmed that the synthesis was achieved with a 100% conversion rate through the change in the integration ratio of peaks 12 and 14 that appeared between 1.7 and 2.3 ppm.

[0101]

[0102] <Experimental Example 2> FT-IR Analysis Results of PCAC3-100 and PCA3SA-100

[0103] The FT-IR analysis results of PCAC3-100 and PCA3SA-100 are shown in Fig. 4. Referring to Fig. 4, 3400 cm⁻¹ -1 A hydrogen bonding peak due to OH can be observed in the vicinity, and at 1320 cm⁻¹ -1 Changes in the terminal functional group were confirmed by examining the nearby S=O peak.

[0104]

[0105] <Experimental Example 3> PCAC3-100, PCA3SA-100 TGA Analysis Results

[0106] The TGA of PCAC3-100 and PCA3SA-100 was measured by the following method. From room temperature to 120 ℃ min 20 ℃ -1 After raising the temperature, it was maintained for 10 minutes to remove residual moisture and stabilize. Subsequently, it was raised to 80 ℃ for 20 ℃ min -1 After cooling to 80 ℃ to 800 ℃ for 10 ℃ min -1 The weight change of the polymer sample was measured in a nitrogen atmosphere.

[0107] Referring to Figure 5 and Table 1, TGA analysis results of PCAC3-100 and PCA3SA-100 confirmed that PCA3SA-100, which contains a sulfonic acid group with a lower thermal decomposition temperature depending on the change in the terminal functional group, has relatively reduced thermal stability.

[0108] When measuring the decomposition temperatures of 5 wt.% and 10 wt.% of PCA3SA-100, it was confirmed that they were 310 ℃ and 365 ℃, respectively.

[0109] SampleT d5 (℃)T d10 (℃)PCAC3-100507540PCA3SA-100334440

[0110]

[0111] <Experimental Example 4> Evaluation of Mechanical Properties of PCA3SA-100 Electrolyte Membrane

[0112] To measure mechanical properties, a 250 N load cell was attached to a LLOYD UTM LS1 machine, and specimens cut according to ASTM D 638 type V were fitted. At an extension rate of 5 mm / min, at least 5 specimens were measured for each type of electrolyte membrane, and the average and standard deviation of the strain-stress curve, Young's modulus, and elongation were calculated.

[0113] Referring to Figure 7 and Table 2, it was confirmed that the PCA3SA-100 electrolyte membrane exhibited excellent mechanical strength, with a tensile strength and elongation of 58 MPa and 43%, respectively.

[0114] SampleTensile Strength (MPa)Young's Modulus(MPa)Elongation at Break(%)PCA3SA-10058.0 ± 5.01900.1 ± 40.142.8 ± 17.0

[0115]

[0116] <Experimental Example 5> Hydrogen ion conductivity of PCA3SA-100 electrolyte membrane

[0117] 1 × 3 cm for hydrogen ion conductivity measurement 2A sample was prepared and attached to a 4-probe cell, and then measured using electrochemical spectroscopy (Bekktech, BT-522MX, USA). The measurement conditions were 100% RH conditions with the cell placed in double distilled water, and resistance values ​​were measured according to temperature changes from 25 ℃ to 80 ℃ and calculated using the following formula.

[0118] Proton conductivity ( ) [mS cm -1 ] = d / RS

[0119] (D is the distance between electrodes, R is the resistance value, and S is the thickness * width of the sample)

[0120] After measuring the temperature at 25°C in distilled water containing the cell, the temperature was raised and the resistance value was measured at each temperature from 30°C to 80°C in 10°C increments, and the resistance value was measured and recorded at each temperature.

[0121] Referring to Fig. 9 and Table 3, the PCA3SA-100 electrolyte membrane is approximately 70 mS cm at 80 °C. -1 It was confirmed that it exhibits conductivity.

[0122] Temp.(℃)PCA3SA-100(mS cm -1 )2526.963031.434037.215044.726051.977060.408070.47

[0123]

[0124] Specific embodiments of the present invention have been examined so far. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the present invention.

Claims

1. A polymer characterized by being represented by the following [Chemical Formula 1]. [Chemical Formula 1] In the above chemical formula 1, The range of n is 0 to 1, and m and z comprise hydrogen or an alkyl group having 1 to 10 carbon atoms, and R1 and R2 are hydrogen, , or is, X is , , or is, Is or It is characterized by being.

2. In Paragraph 1, A polymer characterized by having a weight average molecular weight (Mw) of 10,000 to 1,000,000 g / mol.

3. A cation exchange membrane comprising the polymer of claim 1.

4. A first step of mixing and reacting diphenylcarbazole and 1,1,1-trifluoroacetone; A second step of mixing and reacting the polymer synthesized in the first step with sodium 3-bromopropane-1-sulfonate; A third step of manufacturing a membrane by dissolving the polymer synthesized in the second step above in dimethylsulfoxide (DMSO), and then drying it in a drying oven after casting; and A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by including: a fourth step of immersing the membrane manufactured in the third step above in an aqueous sulfuric acid solution to substitute the functional group terminals of the membrane manufactured above with sulfonic acid groups.

5. In Paragraph 4, The above first step is, A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by mixing 1 to 2 moles of 1,1,1-trifluoroacetone with 1 mole of diphenylcarbazole.

6. In Paragraph 4, The above first step is, A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by using trifluoromethanesulfonic acid (TFSA) as a catalyst and dichloromethane (DCM) as a reaction solvent.

7. In Paragraph 4, The above first step is, A method for preparing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by mixing the above-mentioned diphenylcarbazole and 1,1,1-trifluoroacetone, maintaining at 1 to 10 ℃ for 5 to 20 minutes, and then reacting at room temperature for 1 to 5 hours.

8. In Paragraph 4, The above second step is, A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by using sodium hydroxide (NaOH) as a catalyst and dimethyl sulfoxide (DMSO) as a reaction solvent.

9. In Paragraph 4, The above second step is, A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by mixing 2 to 5 moles of sodium 3-bromopropane-1-sulfonate with 1 mole of the polymer synthesized in the first step above.

10. In Paragraph 4, The above second step is, A method for preparing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by mixing the polymer synthesized in the first step above with sodium 3-bromopropane-1-sulfonate and reacting at 40 to 60 ℃ for 15 to 25 hours.

11. In Paragraph 4, The above third step is, A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by dissolving the polymer synthesized in the second step above in dimethylsulfoxide (DMSO), and then, after casting, drying it in a drying oven at 65 to 85 ℃ for 5 to 10 hours to produce a membrane.

12. In Paragraph 4, The above fourth step is, A method for manufacturing a cation exchange membrane having a sulfonic acid group of a novel structure, characterized by placing the membrane manufactured in the third step above into an aqueous sulfuric acid solution and immersing it at 50 to 70 ℃ for 10 to 15 hours.

13. A water electrolysis system comprising the cation exchange membrane of paragraph 3.

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