Proton exchange membrane for fuel cell with PEDOT introduced into hydrocarbon-based polymer and method for preparing the same

Abstract

One embodiment of the present invention provides a cation exchange membrane for a fuel cell in which PEDOT is introduced into a hydrocarbon-based polymer and a method for manufacturing the same.

Description

Technology Field

[0001] The present invention relates to a cation exchange membrane for a fuel cell, and more specifically, to a cation exchange membrane for a fuel cell in which PEDOT is introduced into a hydrocarbon-based polymer and a method for manufacturing the same. Background Technology

[0002] Fuel cells are one of the future alternative energy sources and are a type of power generation device that directly converts chemical energy within fuel into electrical energy. Depending on the operating temperature and the type of electrolyte, they can be classified into Proton Exchange Membrane Fuel Cells (PEMFC), Alkali Fuel Cells (AFC), Phosphoric Acid Fuel Cells (PAFC), Molten Carbonate Fuel Cells (MCFC), and Solid Oxide Fuel Cells (SOFC).

[0003] Among these, polymer electrolyte fuel cells have a lower operating temperature, higher energy conversion efficiency, and higher current and power densities compared to other fuel cells, while also exhibiting fast response characteristics to load changes. In particular, since polymer membranes are used as electrolytes, the structure is simple and corrosion does not need to be considered, allowing for diverse possibilities in material selection. Consequently, they can be applied to a wide range of industrial fields in the future, such as power sources for zero-emission vehicles, household power, portable power, and military power.

[0004] The cation exchange membrane used in fuel cells serves to separate the anode and cathode and facilitates the movement of protons supplied through the fuel; it is a factor that significantly influences the performance of ion conductivity, which can affect the overall efficiency of the cell.

[0005] Polymer electrolyte fuel cells typically use DuPont's Nafion membrane, a tetrafluoroethylene copolymer containing perfluorosulfonic acid in its side chain, as the electrolyte. While perfluorinated polymers like Nafion have the advantages of high ionic conductivity and excellent mechanical and chemical stability, the cost of Nafion polymer electrolytes is too high due to the complex synthesis process, so a reduction in the cost of the membrane is required for the commercialization of polymer electrolyte fuel cells.

[0006] Furthermore, since the fuel utilization rate decreases and driving performance deteriorates rapidly due to the permeability characteristics of Nafion itself for fuel gases and liquids (methanol), attempts to improve fuel cell performance and simultaneously reduce Nafion usage by decreasing the film thickness to increase conductivity are unrealistic; conversely, there is a problem in that increasing the thickness of the Nafion film lowers conductivity, thereby degrading the output characteristics of the fuel cell.

[0007] Furthermore, Nafion polymer electrolytes exhibit poor dimensional stability depending on the degree of hydration, which not only presents disadvantages in the manufacturing process but also causes performance degradation due to the deterioration of interfacial contact with the numerically stable electrode catalyst layer during prolonged operation. Prior art literature

[0008] Republic of Korea Registered Patent 10-0544890 The problem to be solved

[0009] The technical problem that the present invention aims to solve is to provide a cation exchange membrane by using hydrocarbon polymers to overcome the disadvantages of perfluorinated polymers and mixing them with PEDOT.

[0010] In the case of various hydrocarbon cation exchange membranes synthesized by the above blending process, such as sulfonated poly arylene ether ketone (SPAEK), sulfonated poly ether ether ketone (SPEEK), sulfonated poly arylene ether sulfone (SPAES), sulfonated polybenzimidazol (SPBI), and sulfonated poly fluorene biphenyl indole (SPFBI), doping does not occur due to steric hindrance and electrostatic interactions between the hydrocarbon polymer main chain, sulfonic acid groups, and PEDOT, and proton dissociation is facilitated to improve ion conductivity, and mechanical stability can be improved with low water content and swelling rate due to the hydrophobic PEDOT.

[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 to which the present invention belongs from the description below. means of solving the problem

[0014] To achieve the above technical objectives, one embodiment of the present invention provides a method for manufacturing a cation exchange membrane for a fuel cell.

[0016] In an embodiment of the present invention, the manufacturing method comprises the step (S100) of providing a first hydrocarbon-based polymer having a sulfonic acid group;

[0017] A step (S200) of mixing the first hydrocarbon-based polymer with EDOT (3,4-ethylenedioxythiophene) to form a mixture;

[0018] A step of manufacturing a cation exchange membrane by adding an oxidizing agent to the above mixture (S300); and

[0019] There may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized by including a step (S400) of activating the sulfonic acid group of the cation exchange membrane.

[0021] In an embodiment of the present invention, the step of providing a first hydrocarbon polymer having the sulfonic acid group,

[0022] Step (S10) of providing a second hydrocarbon-based polymer; and

[0023] There may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized by including the step (S20) of synthesizing a first hydrocarbon polymer having sulfonic acid groups by reacting the second hydrocarbon polymer with DSPA (dual sulfonated 3,3-diphenylpropylamine) under a catalyst.

[0024] In an embodiment of the present invention, there may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the second hydrocarbon-based polymer is polymerized using a monomer selected from the group consisting of BPVA (4,4-bis(4-hydroxyphenyl)valeric acid), DFBP (4,4-diflourobenzophenol), and bisphenol A, or a mixture thereof.

[0025] In an embodiment of the present invention, there may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the second hydrocarbon polymer is selected from the group consisting of PEEK (Poly ether ether ketone), PAES (Poly arylene ether sulfone), PBI (Polybenzimidazol), PFBI (Poly fluorine biphenyl indole), and PAEK (Poly arylene ether ketone).

[0026] In an embodiment of the present invention, there may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the catalyst comprises one or more selected from the group consisting of TBTU (O-(benzotriazole-1-yl)-N,N,N,N-tetramethyluroniumtetrafluoroborate) and DIPEA (N,N-Diisopropylethylamine).

[0027] In an embodiment of the present invention, in the step of synthesizing a first hydrocarbon polymer having a sulfonic acid group by reacting the second hydrocarbon polymer with DSPA (dual sulfonated 3,3-diphenylpropylamine) under a catalyst,

[0028] The above reaction is an amidation reaction, and

[0029] There may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the first hydrocarbon polymer having the above-mentioned sulfonic acid group is a double-sulfonated hydrocarbon polymer.

[0030] In an embodiment of the present invention, there may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the oxidizing agent is SPS (Sodium persulfate).

[0032] To achieve the above technical problem, another embodiment of the present invention provides a cation exchange membrane for a fuel cell.

[0033] In an embodiment of the present invention, the cation exchange membrane for a fuel cell comprises a first hydrocarbon-based polymer and PEDOT (poly(3,4-ethylenedioxythiophene)), wherein

[0034] The structure of the first hydrocarbon polymer above is such that the main chain is formed in the form of a carbon ring, and

[0035] The above-mentioned first hydrocarbon polymer includes a sulfonic acid group as a functional group, and

[0036] There may be a cation exchange membrane for a fuel cell characterized by the above-mentioned first hydrocarbon-based polymer and the above-mentioned PEDOT being mixed in a structure that causes steric hindrance and electrostatic interaction with each other.

[0037] In an embodiment of the present invention, there may be a cation exchange membrane for a fuel cell characterized in that the first hydrocarbon polymer is selected from the group consisting of SPEEK (Sulfonated poly ether ether ketone), SPAES (Surfonated poly arylene ether sulfone), SPBI (Surfonated polybenzimidazol), SPFBI (Sulfonated poly fluorine biphenyl indole), and SPAEK (Surfonated poly arylene ether ketone).

[0038] In an embodiment of the present invention, the cation exchange membrane for a fuel cell may be characterized by having a structure of the following chemical formula 1.

[0039] [Chemical Formula 1]

[0041]

[0042] In the above chemical formula 1,

[0043] 0 < n < 1, 0 < m < 1, and (m + n) = 1.

[0045] In an embodiment of the present invention, there may be a cation exchange membrane for a fuel cell characterized by the PEDOT being mixed in a molar ratio of 0.4 to 2 with respect to 1 mole of the first hydrocarbon-based polymer.

[0047] To achieve the above technical problem, another embodiment of the present invention provides a fuel cell.

[0048] In an embodiment of the present invention, the apparatus comprises an oxidation electrode, a reduction electrode, and a polymer electrolyte membrane located between the oxidation electrode and the reduction electrode, wherein

[0049] There may be a fuel cell characterized in that the above polymer electrolyte membrane is a cation exchange membrane for a fuel cell according to claim 1. Effects of the invention

[0051] According to an embodiment of the present invention, the cation exchange membrane for fuel cells synthesized in the present invention is manufactured based on a hydrocarbon polymer, which can replace the high cost of existing perfluorinated polymers, and the low ionic conductivity of hydrocarbon polymers and the water content and swelling rate that determine mechanical properties compared to perfluorinated polymers can be overcome and improved through the introduction of PEDOT.

[0053] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0055] Figure 1 illustrates the manufacturing process of a cation exchange membrane for a fuel cell. Figure 2 illustrates the process of synthesizing the first hydrocarbon polymer. Figure 3 shows the chemical structure of DSPAEK:PEDOT blended with hydrophobic PEDOT to improve the proton conductivity, water content, and swelling rate of the proton exchange membrane. Figure 4 shows the chemical structure of the hydrocarbon polymer PAEK through amination synthesis. Figure 5 shows the chemical structure of sulfonated DSPAEK for use as a fuel cell and proton exchange membrane. Figure 6 illustrates the doping process due to the attractive force between PEDOT and a flexible structure such as Nafion, and the proton dissociation process without doping due to steric hindrance in the case of the hydrocarbon polymer. Figure 7 is a graph showing the improved proton conductivity measurements of membranes prepared by blending various hydrocarbon polymers with PEDOT. Figure 8 is intended to show the difference when PEDOT is blended with a Nafion membrane, which has a flexible main chain unlike hydrocarbon polymers. Nafion: This is a graph showing the measured proton conductivity of the PEDOT membrane. Fig. 9 is a graph showing the measured water content and swelling rate of the membrane blended with hydrophobic PEDOT and the pure membrane, respectively. Specific details for implementing the invention

[0056] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0057] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0058] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0059] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0061] A method for manufacturing a cation exchange membrane for a fuel cell according to one embodiment of the present invention will be described.

[0062] Polymer electrolyte membrane fuel cells (PEMFCs) have been the subject of extensive research due to their advantages of high current density and eco-friendliness. Among the components of a fuel cell, the cation exchange membrane is a polymer electrolyte membrane responsible for the transfer of protons and is a key component that determines the performance of the fuel cell. Perfluorocarbon-based ion exchange membranes, such as Nafion, have been primarily used for this component, but they have limitations in achieving full commercialization, including high costs due to complex synthesis processes and high fuel permeability.

[0064] Figure 1 illustrates the manufacturing process of a cation exchange membrane for a fuel cell.

[0065] Figure 2 illustrates the process of synthesizing the first hydrocarbon-based polymer.

[0067] A method for manufacturing a cation exchange membrane for a fuel cell according to one example of the above embodiment may include the following steps. The following steps are described with reference to FIG. 1.

[0068] Step of providing a first hydrocarbon polymer having sulfonic acid groups (S100), step of mixing the first hydrocarbon polymer with EDOT (3,4-ethylenedioxythiophene) to form a mixture (S200), step of adding an oxidizing agent to the mixture to manufacture a cation exchange membrane (S300), step of activating the sulfonic acid groups of the cation exchange membrane (S400).

[0070] A sulfonic acid group is an atomic group formed by the removal of a hydroxyl group from a sulfuric acid molecule; it is a monovalent atomic group consisting of one hydrogen atom, one sulfur atom, and three oxygen atoms. Its chemical formula is SO3H. Furthermore, a sulfonation reaction refers to a reaction in which the above-mentioned sulfonic acid group (SO3H) is introduced into an organic compound molecule to produce a compound of the RSO3H type. The above R can be an alkyl or aryl group, and such sulfonation reactions are important for the manufacture of dyes or surfactants. For example, there is the reaction in which benzenesulfonic acid is produced from benzene and fuming sulfuric acid.

[0071] EDOT (3,4-ethylenedioxythiophene) is an organic sulfur compound having the chemical formula C2H4O2C4H2S. The EDOT molecule consists of thiophenes substituted with ethylene glycolyl units at the 3rd and 4th positions and is characterized by being colorless and viscous. Additionally, EDOT is a precursor of PEDOT (poly(3,4-ethylenedioxythiophene)), a polymer used in electrochromic displays, photovoltaic cells, electroluminescent displays, printed wiring, and sensors.

[0073] Figure 3 shows the chemical structure of DSPAEK:PEDOT blended with hydrophobic PEDOT to improve the proton conductivity, water content, and swelling rate of the proton exchange membrane.

[0075] A mixture having a chemical structure as shown in FIG. 3 can be formed through the step (S200) of mixing the first hydrocarbon polymer with EDOT (3,4-ethylenedioxythiophene) to form a mixture.

[0077] In a method for manufacturing a cation exchange membrane for a fuel cell according to one example of the above embodiment, the step of providing a first hydrocarbon-based polymer having a sulfonic acid group is described.

[0078] Refer to Figure 2 to explain the following steps.

[0080] A step of having a first hydrocarbon polymer having the above-mentioned sulfonic acid group,

[0081] There may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized by including the step of providing a second hydrocarbon polymer (S10), and the step of synthesizing a first hydrocarbon polymer having a sulfonic acid group by reacting the second hydrocarbon polymer with DSPA (dual sulfonated 3,3-diphenylpropylamine) under a catalyst (S20).

[0083] In a method for manufacturing a cation exchange membrane for a fuel cell according to one example of the above embodiment, the second hydrocarbon-based polymer may be polymerized using a monomer selected from the group consisting of BPVA (4,4-bis(4-hydroxyphenyl)valeric acid), DFBP (4,4-diflourobenzophenol), and bisphenol A, or a mixture thereof.

[0085] The above bisphenol A is a compound primarily used in the manufacture of various plastics. It is a colorless solid that dissolves in most common organic solvents but does not dissolve well in water. BPA is produced on a large scale through the condensation reaction of phenol and acetone, and has a global production scale expected to reach 10 million tons in 2022.

[0086] The largest single application of BPA is as a co-monomer in polycarbonate production, accounting for 65–70% of all BPA production. The manufacture of epoxy resins and vinyl ester resins accounts for 25 to 30% of BPA usage. The remaining 5% is used as a main component in various high-performance plastics and as an additive in PVC, polyurethane, thermal paper, and various other materials.

[0087] In the present invention, the above BPA, BPVA, and DFBP can be used as monomers for the synthesis of hydrocarbon-based polymers such as PEEK (Poly ether ether ketone), PAES (Poly arylene ether sulfone), PBI (Polybenzimidazol), PFBI (Poly fluorine biphenyl indole), and PAEK (Poly arylene ether ketone).

[0089] Figure 4 shows the chemical structure of the hydrocarbon polymer PAEK through amination synthesis.

[0090] Figure 5 shows the chemical structure of sulfonated DSPAEK for use as a fuel cell and proton exchange membrane.

[0092] As an example of the above embodiment, there may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the second hydrocarbon polymer is selected from the group consisting of PEEK (Poly ether ether ketone), PAES (Poly arylene ether sulfone), PBI (Polybenzimidazol), PFBI (Poly fluorine biphenyl indole), and PAEK (Poly arylene ether ketone).

[0093] Referring to Fig. 4, the structure of the above PAEK can be confirmed, and

[0094] Referring to FIG. 5, in the step (S20) of synthesizing a first hydrocarbon polymer having sulfonic acid groups by reacting the second hydrocarbon polymer with DSPA (dual sulfonated 3,3-diphenylpropylamine) under a catalyst, the structure of DSPAEK synthesized when PAEK is used as the second hydrocarbon polymer can be confirmed.

[0096] As an example of the above embodiment, there may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the catalyst comprises one or more selected from the group consisting of TBTU (O-(benzotriazole-1-yl)-N,N,N,N-tetramethyluroniumtetrafluoroborate)) and DIPEA (N,N-Diisopropylethylamine).

[0098] As an example of the above embodiment, in the step of synthesizing a first hydrocarbon polymer having a sulfonic acid group by reacting the second hydrocarbon polymer with DSPA (dual sulfonated 3,3-diphenylpropylamine) under a catalyst,

[0099] The above reaction is an amidation reaction, and

[0100] There may be a method for manufacturing a cation exchange membrane for a fuel cell, characterized in that the first hydrocarbon polymer having the above-mentioned sulfonic acid group is a double-sulfonated hydrocarbon polymer.

[0102] The amidation reaction is a reaction that introduces an amide group into an organic compound molecule, wherein the amide is a compound in which a hydrogen atom of ammonia or an amine is substituted with an acid group (acyl group) or a metal atom. Those substituted with acyl groups, with the exception of formamide, are mostly colorless crystals used as raw materials for organic synthesis, while those substituted with metals are white solids that decompose and produce ammonia when water is added. The amide can be produced through a condensation reaction between an amine and a carboxylic acid.

[0104] As an example of the above embodiment, there may be a method for manufacturing a cation exchange membrane for a fuel cell characterized in that the oxidizing agent is SPS (Sodium persulfate).

[0106] Sodium persulfate (SPS) is an inorganic compound with the chemical formula Na2S2O8, and is the sodium salt of peroxydisulfate (H2S2O8), an oxidizing agent. SPS is a white solid that is soluble in water and is characterized by low hygroscopicity and a long shelf life. Sodium persulfate (SPS) is frequently used in the chemical industry as a specialized oxidizing agent and is classically used in Elbs persulfate oxidation reactions, Boyland-Sims oxidation reactions, and radical reactions.

[0108] A cation exchange membrane for a fuel cell according to one embodiment of the present invention will be described.

[0109] As an example of the above embodiment, the first hydrocarbon-based polymer and PEDOT (poly(3,4-ethylenedioxythiophene)) are included,

[0110] The structure of the first hydrocarbon polymer above is such that the main chain is formed in the form of a carbon ring, and

[0111] The above-mentioned first hydrocarbon polymer includes a sulfonic acid group as a functional group, and

[0112] There may be a cation exchange membrane for a fuel cell characterized by the above-mentioned first hydrocarbon-based polymer and the above-mentioned PEDOT being mixed in a structure that causes steric hindrance and electrostatic interaction with each other.

[0114] Figure 6 illustrates the doping process resulting from the attractive force between a flexible structure such as Nafion and PEDOT, and the proton dissociation process without doping due to steric hindrance in the case of hydrocarbon polymers, respectively.

[0116] The above embodiment and stereoscopic effect will be explained with reference to FIG. 6.

[0117] A steric effect refers to the effect that the size of a substituent located near the reaction center has on the reactivity of a substance. It is one of the important substituent effects, along with electronic effects such as polar effects (organic effects) and resonance effects (mesomerial effects). When this effect acts to hinder the progress of a reaction, it is called steric hindrance, and when it acts to promote the progress of a reaction, it is called steric acceleration.

[0118] For example, if large substituents are densely clustered around the carbon atom being attacked by the ionoid reagent, they hinder the reagent's approach. Because of this, the S of the bimolecular mechanism N Type II reactions are difficult to occur due to steric hindrance of substituents. However, S of the unimolecular mechanism N In a Type 1 reaction, the rate-determining step is the formation of the carbonium ion, and the reaction is accelerated because the spacing between substituents widens and the exchange repulsion is alleviated.

[0119] In the case of one example of the present embodiment,

[0120] The characteristic corresponding to steric hindrance among the aforementioned steric effects is utilized. The hydrocarbon polymer has a chemical structure in which the main chain consists of rings; due to steric hindrance with PEDOT, protons are not doped, and the electrostatic attraction with PEDOT influences proton dissociation, resulting in the effect of having higher ionic conductivity.

[0122] This is a result that contrasts with the previously used Nafion.

[0123] In the case of Nafion, due to its flexible main chain chemical structure, the distance between Nafion and PEDOT is relatively close compared to the aforementioned hydrocarbon polymers, resulting in doping through deprotonation. Consequently, when PEDOT is introduced into Nafion, it exhibits lower ionic conductivity than before the introduction of PEDOT.

[0124] Looking at Fig. 6(a), it can be seen that Nafion's flexible main chain structure allows it to maintain a relatively close distance to PEDOT, and deprotonation and doping can be visually confirmed.

[0125] Looking at Fig. 6(b), it can be observed that, unlike in the case of Nafion, DSPAEK and PEDOT can maintain a relatively long distance due to the influence of steric hindrance. This is because a cyclic hydrocarbon exists between the carbon main chain and the sulfonate group.

[0127] As an example of the above embodiment, there may be a cation exchange membrane for a fuel cell characterized in that the first hydrocarbon polymer is selected from the group consisting of SPEEK (Sulfonated poly ether ether ketone), SPAES (Surfonated poly arylene ether sulfone), SPBI (Surfonated polybenzimidazol), SPFBI (Sulfonated poly fluorine biphenyl indole), and SPAEK (Surfonated poly arylene ether ketone).

[0129] As an example of the above embodiment, there may be a cation exchange membrane for a fuel cell characterized by having a structure of the following chemical formula 1.

[0131] [Chemical Formula 1]

[0132]

[0133] In the above chemical formula 1,

[0134] 0 < n < 1, 0 < m < 1, and is composed as (m + n) = 1.

[0135] As an example of the above embodiment, there may be a cation exchange membrane for a fuel cell characterized by the PEDOT being mixed in a molar ratio of 0.4 to 2 with respect to 1 mole of the first hydrocarbon-based polymer.

[0137] At this time, as the molar ratio of the first hydrocarbon-based polymer and the PEDOT changes, properties such as water content and swelling rate of the cation exchange membrane for the fuel cell change, and as the proportion of hydrophobic PEDOT increases, both the water content and swelling rate tend to decrease. This is because the proportion of hydrophobic PEDOT increases and the interaction between the hydrophilic sulfonic acid group and PEDOT increases.

[0139] Moisture content refers to the proportion of the weight of water to the total weight. In other words, it is calculated as a percentage by dividing the difference between the weight before and after drying by the weight before drying, when a sample, such as fiber, has reached moisture equilibrium from a low moisture content under standard conditions.

[0140] Swelling rate refers to a value expressed as a percentage of the original dimensions indicating the degree to which a sample, such as a fiber, expands as the moisture content increases. In other words, it means a numerical representation of the degree to which a sample expands as the proportion of the weight of water in the total weight increases.

[0142] As shown in one example of the above embodiment, when the water content and swelling rate of the proton exchange membrane are lowered, excellent effects can be obtained in terms of ion conductivity and mechanical stability.

[0144] A fuel cell according to one embodiment of the present invention will be described.

[0146] As an example of the above embodiment,

[0147] The apparatus comprises an oxidation electrode, a reduction electrode, and a polymer electrolyte membrane located between the oxidation electrode and the reduction electrode, wherein

[0148] There may be a fuel cell characterized in that the above-described polymer electrolyte membrane is a cation exchange membrane for a fuel cell.

[0150] The description of the above-mentioned cation exchange membrane for fuel cells is omitted as it has been specifically detailed above.

[0151] Due to the excellent properties of the cation exchange membrane for the fuel cell described above, a fuel cell comprising the cation exchange membrane also retains excellent performance, such as improved ion conductivity and mechanical stability.

[0153] Preparation Example 1. DSPAEK:PEDOT(1.0:0.5)

[0154] A cation exchange membrane for fuel cells was prepared with a molar ratio of DSPAEK and PEDOT of 1.0:0.5.

[0155] The manufacturing process of DSPAEK:PEDOT(1.0:0.5) is described with reference to FIGS. 1 and FIGS. 2.

[0156] Step of providing PAEK (S10);

[0157] A step (S20) of synthesizing the above PAEK into DSPAEK through an amidation reaction with DSPA, TBTU, and DIPEA;

[0158] A step (S200) of mixing the above DSPAEK with EDOT to form a mixture by mixing DSPAEK and PEDOT such that the molar ratio is 1.0:0.5;

[0159] A step of preparing a cation exchange membrane by adding an oxidizing agent sodium persulfate to the above mixture (S300); and

[0160] DSPAEK:PEDOT (1.0:0.5) was prepared by activating the sulfonic acid groups of the above cation exchange membrane using 2M HCl (S400).

[0162] Preparation Example 2. DSPAEK:PEDOT(1.0:1.0)

[0163] A cation exchange membrane for fuel cells was prepared with a molar ratio of DSPAEK and PEDOT of 1.0:1.0.

[0164] The manufacturing process of DSPAEK:PEDOT(1.0:1.0) is described with reference to FIGS. 1 and FIGS. 2.

[0165] Step of providing PAEK (S10);

[0166] A step (S20) of synthesizing the above PAEK into DSPAEK through an amidation reaction with DSPA, TBTU, and DIPEA;

[0167] A step (S200) of mixing the above DSPAEK with EDOT to form a mixture such that the molar ratio of DSPAEK to PEDOT is 1.0:1.0;

[0168] A step of preparing a cation exchange membrane by adding an oxidizing agent sodium persulfate to the above mixture (S300); and

[0169] DSPAEK:PEDOT(1.0:1.0) was prepared by activating the sulfonic acid groups of the above cation exchange membrane using 2M HCl (S400).

[0171] Preparation Example 3. DSPAEK:PEDOT(1.0:1.5)

[0172] A cation exchange membrane for fuel cells was prepared with a molar ratio of DSPAEK and PEDOT of 1.0:1.5.

[0173] The manufacturing process of DSPAEK:PEDOT(1.0:1.5) is described with reference to FIGS. 1 and FIGS. 2.

[0174] Step of providing PAEK (S10);

[0175] A step (S20) of synthesizing the above PAEK into DSPAEK through an amidation reaction with DSPA, TBTU, and DIPEA;

[0176] A step (S200) of mixing the above DSPAEK with EDOT to form a mixture such that the molar ratio of DSPAEK to PEDOT is 1.0:1.5;

[0177] A step of preparing a cation exchange membrane by adding an oxidizing agent sodium persulfate to the above mixture (S300); and

[0178] DSPAEK:PEDOT (1.0:1.5) was prepared by activating the sulfonic acid groups of the above cation exchange membrane using 2M HCl (S400).

[0180] Comparative Preparation Example 1. SPAES:PEDOT

[0181] A cation exchange membrane for fuel cells was prepared by mixing SPAES and PEDOT.

[0182] The manufacturing process of SPAES:PEDOT is described with reference to Figures 1 and 2.

[0183] Step of providing PAES (S10);

[0184] A step (S20) of synthesizing the above PAES into SPAES through an amidation reaction;

[0185] A step of mixing the above SPAES with EDOT to form a mixture (S200);

[0186] A step of preparing a cation exchange membrane by adding an oxidizing agent to the above mixture (S300); and

[0187] SPAES:PEDOT was prepared by going through the step (S400) of activating the sulfonic acid groups of the above cation exchange membrane using 2M HCl.

[0188] Comparative Preparation Example 2. SPFBI:PEDOT

[0189] A cation exchange membrane for fuel cells was prepared by mixing SPFBI and PEDOT.

[0190] The manufacturing process of SPFBI:PEDOT is described with reference to Figures 1 and 2.

[0191] Step of providing PFBI (S10);

[0192] A step (S20) of synthesizing the above PFBI into SPFBI through an amidation reaction;

[0193] A step of forming a mixture by mixing the above SPFBI with EDOT (S200);

[0194] A step of preparing a cation exchange membrane by adding an oxidizing agent to the above mixture (S300); and

[0195] SPFBI:PEDOT was prepared by going through the step (S400) of activating the sulfonic acid groups of the above cation exchange membrane using 2M HCl.

[0196] Comparative Preparation Example 3. SPEEK:PEDOT

[0197] A cation exchange membrane for fuel cells was prepared by mixing SPEEK and PEDOT.

[0198] The manufacturing process of SPEEK:PEDOT is described with reference to FIGS. 1 and FIGS. 2.

[0199] Step of providing PEEK (S10);

[0200] A step (S20) of synthesizing the above PEEK into SPEEK through an amidation reaction;

[0201] A step (S200) of mixing the above SPEEK with EDOT to form a mixture;

[0202] A step of preparing a cation exchange membrane by adding an oxidizing agent to the above mixture (S300); and

[0203] SPEEK:PEDOT was prepared by going through the step (S400) of activating the sulfonic acid groups of the above cation exchange membrane using 2M HCl.

[0204] Experimental Example 1. Ionic Conductivity Analysis

[0205] The change in ionic conductivity due to the introduction of PEDOT in the above Preparation Example 1, Comparative Preparation Examples 1 to 3, and commercial Nafion polymers was measured and analyzed.

[0207] Figure 7 is a graph showing the improved proton conductivity measurements of a membrane prepared by blending various hydrocarbon polymers with PEDOT.

[0208] Figure 8 is a graph showing the proton conductivity measurements of a Nafion:PEDOT membrane to show the difference when blending a Nafion membrane, which has a flexible main chain unlike hydrocarbon polymers, with PEDOT.

[0210] Referring to Figures 6, 7, and 8, it can be seen that in the case of hydrocarbon-based polymers including DSPAEK, the ionic conductivity increased in all temperature ranges due to the introduction of PEDOT, whereas in the case of the perfluorinated polymer Nafion, the ionic conductivity actually decreased in all temperature ranges due to the introduction of PEDOT.

[0211] Referring to Fig. 6(b), hydrocarbon polymers have a chemical structure in which the main chain consists of rings, so they are not doped with protons due to the steric effect with PEDOT. Additionally, the electrostatic attraction with PEDOT influences the dissociation of protons, resulting in higher ionic conductivity.

[0212] Referring to Fig. 6(a), it can be seen that, unlike the hydrocarbon polymer, the commercial Nafion polymer has a flexible chemical structure for its main chain. Due to this flexible chemical structure of the main chain, the distance between the commercial Nafion polymer and PEDOT is relatively closer compared to the hydrocarbon polymer, so deprotonation occurs and doping takes place. Due to this difference, unlike the hydrocarbon polymer, the ionic conductivity of Nafion, a perfluorinated polymer, actually decreases across the entire temperature range due to the introduction of PEDOT.

[0214] Experimental Example 2. Analysis of Moisture Content and Swelling Rate

[0215] To compare the physical properties of the above Preparation Examples 1 to 3 and DSPAEK without added PEDOT, the water content and swelling rate of DSPAEK:PEDOT cation exchange membranes prepared by mixing PEDOT with DSPAEK in various ratios were analyzed.

[0216] Figure 9 is a graph showing the measured values ​​of water content and swelling rate of a membrane blended with hydrophobic PEDOT and a pure membrane, respectively.

[0218] Referring to Fig. 9, basically, both the water content and the swelling rate show an increasing trend as the temperature rises. Additionally, it can be observed that the water content and the swelling rate decrease as the proportion of added PEDOT increases, which is because the proportion of hydrophobic PEDOT increases and the interaction between the hydrophilic sulfonic acid groups and PEDOT increases.

[0220] In the above experimental examples, the one with the lowest water content and swelling rate is the DSPAEK:PEDOT(1.0:1.5) proton exchange membrane produced by the process of Preparation Example 3. By introducing PEDOT in this way to lower the water content and swelling rate of the proton exchange membrane, excellent effects can be obtained in terms of ion conductivity and mechanical stability.

[0222] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0223] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

Claim 1 A method for manufacturing a cation exchange membrane for a fuel cell, comprising: a step of providing a first hydrocarbon polymer having sulfonic acid groups; a step of mixing the first hydrocarbon polymer with EDOT (3,4-ethylenedioxythiophene) to form a mixture; a step of adding an oxidizing agent to the mixture to manufacture a cation exchange membrane; and a step of activating the sulfonic acid groups of the cation exchange membrane; wherein the step of providing the first hydrocarbon polymer having sulfonic acid groups comprises: a step of providing a second hydrocarbon polymer; and a step of converting the second hydrocarbon polymer into a first hydrocarbon polymer having sulfonic acid groups by amidating it with DSPA (dual sulfonated 3,3-diphenylpropylamine) under a catalyst. Claim 2 delete Claim 3 A method for manufacturing a cation exchange membrane for a fuel cell according to claim 1, characterized in that the second hydrocarbon-based polymer is polymerized using a monomer selected from the group consisting of BPVA, DFBP, and bisphenol A, or a mixture thereof. Claim 4 A method for manufacturing a cation exchange membrane for a fuel cell according to claim 1, characterized in that the second hydrocarbon polymer is selected from the group consisting of PEEK (Poly ether ether ketone), PAES (Poly arylene ether sulfone), PBI (Polybenzimidazol), PFBI (Poly fluorine biphenyl indole), and PAEK (Poly arylene ether ketone). Claim 5 A method for manufacturing a cation exchange membrane for a fuel cell according to claim 1, characterized in that the catalyst comprises one or more selected from the group consisting of TBTU and DIPEA. Claim 6 A method for manufacturing a cation exchange membrane for a fuel cell, characterized in that, in claim 1, the first hydrocarbon polymer having a sulfonic acid group is a double sulfonated hydrocarbon polymer. Claim 7 A method for manufacturing a cation exchange membrane for a fuel cell, characterized in that, in claim 1, the oxidizing agent is SPS (Sodium persulfate). Claim 8 A cation exchange membrane for a fuel cell comprising a first hydrocarbon polymer and PEDOT (poly(3,4-ethylenedioxythiophene)), wherein the first hydrocarbon polymer comprises a carbon ring main chain structure and a sulfonic acid functional group, and the first hydrocarbon polymer is synthesized through an amidation reaction under a catalyst with a second hydrocarbon polymer, DSPA (dual sulfonated 3,3-diphenylpropylamine). Claim 9 A cation exchange membrane for a fuel cell according to claim 8, characterized in that the first hydrocarbon polymer is selected from the group consisting of SPEEK, SPAES, SPBI, SPFBI, and SPAEK. Claim 10 In claim 8, the cation exchange membrane for a fuel cell is characterized by having a structure of the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, 0 < n < 1, 0 < m < 1, and (m + n) = 1. Claim 11 A cation exchange membrane for a fuel cell according to claim 8, characterized in that the PEDOT is mixed in a molar ratio of 0.4 to 2 with respect to 1 mole of the first hydrocarbon-based polymer. Claim 12 A fuel cell comprising an oxidation electrode, a reduction electrode, and a polymer electrolyte membrane located between the oxidation electrode and the reduction electrode, wherein the polymer electrolyte membrane is a cation exchange membrane for a fuel cell according to claim 1.

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