Propargyl group-grafted poly(arylpiperidinium) copolymer ionomer, crosslinked anion exchange membrane and method for producing the same

Abstract

The present invention relates to a poly(arylpiperidinium) copolymer ionomer that does not contain an aryl ether bond in the polymer backbone but has propargyl groups grafted thereto and piperidinium groups introduced therein, an anion exchange membrane crosslinked therefrom, and a method for manufacturing the same. The propargyl group-grafted poly(arylpiperidinium) copolymer ionomer exhibits excellent chemical and thermal stability, ionic conductivity, mechanical properties, dimensional stability, and durability. Furthermore, the crosslinked anion exchange membrane manufactured therefrom exhibits significantly improved catalyst layer peel strength and promotes interaction between the ionomer and the membrane, stabilizing the catalyst layer and thereby dramatically improving fuel cell durability.

Description

[Technical Field]

[0001] The present invention relates to a poly(arylpiperidinium) copolymer ionomer grafted with propargyl groups, a crosslinked anion exchange membrane, and a method for producing the same. More specifically, the present invention relates to a technology for synthesizing a poly(arylpiperidinium) copolymer ionomer that does not have an aryl ether bond in the polymer backbone but has propargyl groups grafted thereto and piperidinium groups introduced therein, producing a crosslinked anion exchange membrane from the same, and applying the membrane to alkaline fuel cells, water electrolysis devices, etc. [Background technology]

[0002] Fuel cells (anion exchange membrane fuel cells, AEMFCs) and water electrolysis (anion exchange membrane water electrolysis, AEMWEs) that utilize anion exchange membranes are promising energy conversion materials that can replace expensive proton exchange membrane fuel cells (PEMFCs). Anion exchange membrane fuel cells or water electrolysis technology has made remarkable progress in recent years thanks to the development of non-platinum catalyst anion exchange membranes and ionomers with high activity, durability, and conductivity.

[0003] The advanced anion exchange membrane exhibits remarkable chemical stability (<10% degradation) in harsh alkaline environments (80°C, 1M NaOH or KOH solution, over 1,000 hours) with a conductivity of 150 mS cm at 80°C. -1 Recently, AEMFCs have achieved an anion conductivity of 2 Wcm, a level similar to that of commercial PEMFCs. -2 However, the majority of AEMFCs still have durability issues during long-term operation. -2 Below, no AEMFC has been reported that can operate stably at 80°C for more than 500 hours.

[0004] The poor durability of AEMFCs is due to unstable contact between the catalyst layer and the membrane. The interfacial stability between the catalyst layer and the membrane, where the electrochemical reaction occurs, is one of the factors that determine the performance and lifespan of AEMFCs and AEMWEs. Rapid moisture adsorption and desorption in the catalyst layer, especially under high current density conditions, can disrupt the interfacial stability between the catalyst layer and the membrane, leading to the aggregation and desorption of catalyst particles from the catalyst layer. Furthermore, excessive swelling of the ionomer can impede the transport of hydrogen gas (the fuel). An ideal catalyst layer should be porous and have a stable three-phase interfacial structure, with uniformly distributed catalyst, and a durable chemical structure between the membrane and the ionomer. This is due to the excellent adhesive properties of the ionomer, which can reduce the interfacial resistance between the catalyst layer and the anion exchange membrane and improve the stability of the catalyst layer. Therefore, developing technologies to stabilize the catalyst layer is crucial for achieving durable AEMFCs and AEMWEs.

[0005] On the other hand, a poly(arylpiperidinium) anion exchange membrane with a crosslinked structure in which no aryl ether bond is present in the polymer backbone, propargyl groups are grafted, and piperidinium groups are introduced has not yet been synthesized, and no specific technology for applying this to alkaline fuel cells or water electrolysis fields has been known.

[0006] Therefore, the inventors have conducted extensive research to expand the application fields of aromatic polymer ion exchange membranes, which have excellent thermal and chemical stability and mechanical properties. As a result, in order to improve the durability, which is a weak point of conventional AEMFCs, they attempted to dramatically improve the durability of AEMFCs by stabilizing the catalyst layer not only in the catalyst layer itself but also by promoting the interfacial interaction between the catalyst layer and AEM.

[0007] That is, the inventors synthesized a poly(arylpiperidinium) copolymer ionomer that does not have an aryl ether bond in the polymer backbone, but has a propargyl group grafted thereon and a piperidinium group introduced therein, and discovered that by using this to manufacture an anion exchange membrane with a crosslinked structure, it can be applied to alkaline fuel cells, water electrolysis devices, supercapacitors, carbon dioxide reduction devices, oxidation-reduction flow batteries, etc., and thus completed the present invention. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 10-2021-0071810 [Patent Document 2] International Publication No. 2019 / 068051 [Patent Document 3] Chinese Patent Application Publication No. 109384908 [Patent Document 4] US Patent Application Publication No. 2019 / 0036143 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised in view of the above-mentioned problems, and a first object of the present invention is to provide a propargyl group-grafted poly(arylpiperidinium) copolymer ionomer having high chemical and thermal stability, ionic conductivity, mechanical properties, dimensional stability, and durability, and a method for producing the same.

[0010] The second object of the present invention is to prepare an anion exchange membrane having a crosslinked structure from the novel propargyl group-grafted poly(arylpiperidinium) copolymer ionomer, thereby significantly improving the dimensional stability of the membrane and promoting the interaction between the catalyst layer and the anion exchange membrane, thereby stabilizing the catalyst layer and dramatically improving durability, thereby applying the membrane to alkaline fuel cells, water electrolysis devices, supercapacitors, carbon dioxide reduction devices, oxidation-reduction flow batteries, etc. [Means for solving the problem]

[0011] To achieve the above object, the present invention provides a propargyl group-grafted poly(arylpiperidinium) copolymer ionomer having a repeating unit represented by the following <Chemical Formula 1>:

[0012] <Chemical formula 1> [ka]

[0013] (In the above Chemical Formula 1, Aryl is two or more different compounds selected from compounds represented by the following structural formulas:

[0014] [ka]

[0015] The present invention also provides (I) a polymerizable composition comprising, as a monomer, (a) two or more different compounds selected from compounds represented by the following structural formulas: [ka] and (b) dissolving 1-methyl-4-piperidone in an organic solvent to form a solution; (II) gradually adding a strong acid catalyst to the solution, stirring and reacting to obtain a viscous solution; (III) precipitating, washing and drying the viscous solution to obtain a solid polymer; (IV) adding and reacting potassium carbonate, propargyl bromide, and an excess amount of halomethane to a polymer solution prepared by dissolving the solid polymer in an organic solvent to form a quaternary piperidinium salt grafted with a propargyl group; and (V) precipitating, washing, and drying the mixed solution.

[0016] The present invention also provides an anion exchange membrane crosslinked using the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer.

[0017] The present invention also provides a method for producing a crosslinked anion exchange membrane, comprising: (i) dissolving the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer in an organic solvent to form a polymer solution; (ii) casting the polymer solution onto a glass plate and heating it to remove the organic solvent to obtain a dried membrane; (iii) heat-treating the dried membrane to obtain a membrane in which a crosslinking reaction has been induced; and (iv) treating the obtained membrane with 1M NaHCO3 or 1M NaOH, followed by washing with ultrapure water several times and drying.

[0018] The present invention also provides an alkaline fuel cell comprising the crosslinked anion exchange membrane.

[0019] The present invention also provides a water electrolysis device comprising the crosslinked anion exchange membrane.

[0020] The present invention also provides a supercapacitor comprising the crosslinked anion exchange membrane.

[0021] The present invention also provides a carbon dioxide reduction device comprising the crosslinked anion exchange membrane.

[0022] The present invention also provides an oxidation-reduction flow battery comprising the crosslinked anion exchange membrane. [Effects of the Invention]

[0023] The propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to the present invention has excellent chemical and thermal stability, ionic conductivity, mechanical properties, dimensional stability and durability.

[0024] Furthermore, the crosslinked anion exchange membrane manufactured from the novel propargyl group-grafted poly(arylpiperidinium) copolymer ionomer significantly improves the peel strength of the catalyst layer and promotes the interaction between the ionomer and the membrane, thereby stabilizing the catalyst layer and dramatically improving the durability of fuel cells. [Brief explanation of the drawings]

[0025] [Figure 1] 1H NMR spectra of the propargyl-grafted poly(arylpiperidinium) copolymer ionomer Trip-PFBP-Pr-m series and PDTP-Pr-m series (m is 10, 30, 50) obtained in Synthesis Examples 1 to 6 of the present invention. [Figure 2] 1 is a graph showing (A) the functional coefficient and (B) the expansion coefficient of the anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series (m is 10, 30, 50) crosslinked after heat treatment of Production Examples 1 to 6 of the present invention at 170°C for 0 minutes, 120 minutes, and 240 minutes, respectively. [Figure 3] 1 is a graph showing the crosslinking degree of the x-PDTP-Pr-50 anion exchange membrane obtained in Preparation Example 3 of the present invention after different heat treatment times. (A) is the FT-IR spectrum of the x-PDTP-Pr-50 anion exchange membrane after different heat treatment times. (B) is the propargyl group remaining in the x-PDTP-Pr-50 anion exchange membrane after different heat treatment times (calculated by integrating the propargyl group in the FT-IR spectrum). [Figure 4]1 shows images of the contact angles measured between the anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series (m is 10, 30, 50) crosslinked after heat treatment of Preparation Examples 1 to 6 of the present invention at 170°C for 120 minutes and the PDTP and Trip-PFBP prepared in Comparative Examples 1 and 2. [Figure 5] FIG. 1 shows thermogravimetric analysis (TGA) graphs (m is 10, 30, 50) of the Trip-PFBP-Pr-m series and PDTP-Pr-m series (before heat treatment) obtained from Synthesis Examples 1 to 6 of the present invention, and the anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series crosslinked after heat treatment of Production Examples 1 to 6 at 170°C for 120 minutes. [Figure 6] 1 is a graph (at 30°C) showing the CO3 2- conductivities of the crosslinked anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series (m is 10, 30, 50) of Production Examples 1 to 6 of the present invention after heat treatment at 170°C for 0 minutes, 120 minutes, and 240 minutes, respectively. [Figure 7] 1 is a graph showing the peel strength of catalyst-coated membranes depending on different copolymer ionomers and types of anion exchange membranes. [Figure 8A] Electrochemical stability data of the catalyst layer analyzed using a rotating disk electrode (RDE) test [transmission electron microscope images, average nanoparticle size, linear scan voltammograms (LSV) measurements of the oxygen reduction reaction (ORR) of catalysts with different ionomers, respectively]. (A) Trip-PFBP. [Figure 8B] Electrochemical stability data of the catalyst layer analyzed using a rotating disk electrode (RDE) test [transmission electron microscope images, average nanoparticle size, and linear scan voltammograms (LSV) measurements of the oxygen reduction reaction (ORR) of catalysts with different ionomers, respectively]. (B) x-Trip-PFBP-10. [Figure 8C]Electrochemical stability data of the catalyst layer analyzed using a rotating disk electrode (RDE) test [transmission electron microscope image, average nanoparticle size, linear scan voltammograms (LSV) measurement of the oxygen reduction reaction (ORR) of catalysts with different ionomers, respectively (C) x-Trip-PFBP-30]. [Figure 8D] Electrochemical stability data of the catalyst layer analyzed using a rotating disk electrode (RDE) test [transmission electron microscope images, average nanoparticle size, and linear scan voltammograms (LSV) measurements of the oxygen reduction reaction (ORR) of catalysts with different ionomers (D)x-Trip-PFBP-50)]. [Figure 9] 1 is a graph showing fuel cell performance depending on the crosslinking degree of a copolymer ionomer and an anion exchange membrane. [Figure 10] 1 is a graph measuring the in-situ durability of a fuel cell based on x-PDTP-Pr-10 anion exchange membrane with asymmetric copolymer ionomer. [Figure 11] 1 is a graph showing the water electrolysis performance (linear scan voltammograms, LSV) and resistance (potentiostatic electrochemical impedance spectroscopy, PEIS) depending on the degree of crosslinking of a copolymer ionomer, temperature, and alkali composition. [Figure 12] 1 is a graph showing the results of an in-situ durability test of the negative electrolysis-based x-PDTP-Pr-10 anion exchange membrane measured under conditions of 60° C., 1 M KOH solution, and different current densities (0.5 A cm −2 , 1.0 cm −2 , 1.5 A cm −2 ). DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer, crosslinked anion exchange membrane, and method for manufacturing the same according to the present invention will be described in detail.

[0027] The present invention provides a propargyl-grafted poly(arylpiperidinium) copolymer ionomer having a repeating unit represented by the following <Chemical Formula 1>:

[0028] <Chemical formula 1> [ka]

[0029] (In the above Chemical Formula 1, Aryl is two or more different compounds selected from compounds represented by the following structural formulas:

[0030] [ka]

[0031] As can be seen from Chemical Formula 1 above, the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to the present invention does not essentially have an aryl ether group in the polymer backbone, and because the propargyl group is grafted and the piperidinium group is included, it has excellent film-forming performance and chemical and thermal stability.

[0032] In addition, the ionic conductivity, mechanical properties, dimensional stability, and durability are also significantly improved. In particular, when used as an anion exchange membrane, the crosslinking structure formed by the propargyl group after heat treatment improves hydrophobicity, reducing the water content and expansion rate.

[0033] The present invention also provides (I) a polymerizable composition comprising, as a monomer, (a) two or more different compounds selected from compounds represented by the following structural formulas: [ka] and (b) dissolving 1-methyl-4-piperidone in an organic solvent to form a solution; (II) gradually adding a strong acid catalyst to the solution, stirring and reacting to obtain a viscous solution; (III) precipitating, washing and drying the viscous solution to obtain a solid polymer; (IV) adding and reacting potassium carbonate, propargyl bromide, and an excess amount of halomethane to a polymer solution prepared by dissolving the solid polymer in an organic solvent to form a quaternary piperidinium salt grafted with a propargyl group; and (V) precipitating, washing, and drying the mixed solution.

[0034] Here, the organic solvent in step (I) may be at least one halogen-based solvent selected from the group consisting of dichloromethane, chloroform, dichloroethane, dibromomethane, and tetrachloroethane, and preferably dichloromethane.

[0035] The strong acid catalyst in step (II) may be trifluoroacetic acid, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoro-1-propanesulfonic acid, perfluoropropionic acid, heptafluorobutyric acid, or a mixture thereof.

[0036] The organic solvent in step (IV) may be N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, or dimethylformamide.

[0037] In step (IV), the polymer is reacted with a halomethane to form a quaternary piperidinium salt. The halomethane may be fluoromethane, chloromethane, bromomethane, or iodomethane, and preferably iodomethane is used.

[0038] The present invention also provides an anion exchange membrane crosslinked from the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer.

[0039] The anion exchange membrane according to the present invention not only exhibits significantly improved mechanical durability but also increased alkaline stability. In particular, when applied to alkaline fuel cells or water electrolysis devices, it promotes interaction between the catalyst layer and the anion exchange membrane, thereby exhibiting low contact resistance and stabilizing the catalyst layer. Therefore, the crosslinked anion exchange membrane based on the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to the present invention has excellent electrochemical stability and thus excellent performance and durability in alkaline fuel cells or water electrolysis devices.

[0040] The present invention also provides a method for producing a crosslinked anion exchange membrane, comprising: (i) dissolving the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer in an organic solvent to form a polymer solution; (ii) casting the polymer solution onto a glass plate and heating it to remove the organic solvent to obtain a dried membrane; (iii) heat-treating the dried membrane to obtain a membrane in which a crosslinking reaction has been induced; and (iv) treating the obtained membrane with 1M NaHCO3 or 1M NaOH, followed by washing with ultrapure water several times and drying.

[0041] Here, the organic solvent in step (i) may be N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, or dimethylformamide.

[0042] The concentration of the polymer solution is preferably 2 to 30% by weight, and more preferably 3.0 to 5.0% by weight. If the concentration of the polymer solution is less than 2% by weight, the film-forming ability may decrease, while if it exceeds 30% by weight, the viscosity may become too high, and the physical properties of the film may decrease after film formation.

[0043] In step (ii), the organic solvent is gradually removed in an oven at 80 to 90°C for 24 hours to obtain a dried membrane. Next, in step (iii), the dried membrane is heat-treated in a dark, vacuum environment at 160 to 180°C for 120 to 240 minutes to produce an anion exchange membrane in which the crosslinking reaction is completed after the initiation of the trimerization reaction and the coupling reaction.

[0044] The synthesis process of the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to the present invention can be represented by the reaction pathway shown in Scheme 1 below.

[0045] [ka]

[0046] Scheme 1. Synthesis route of propargyl-grafted poly(arylpiperidinium) copolymer ionomer (in the above reaction scheme, Aryl is as defined in Chemical Formula 1 above).

[0047] The present invention also provides an alkaline fuel cell comprising the crosslinked anion exchange membrane.

[0048] The present invention also provides a water electrolysis device comprising the crosslinked anion exchange membrane.

[0049] The present invention also provides a supercapacitor comprising the crosslinked anion exchange membrane.

[0050] The present invention also provides a carbon dioxide reduction device comprising the crosslinked anion exchange membrane.

[0051] The present invention also provides an oxidation-reduction flow battery comprising the crosslinked anion exchange membrane.

[0052] Examples and comparative examples according to the present invention will be specifically described below with reference to the accompanying drawings. [Example]

[0053] [Synthesis Examples 1 to 3] Preparation of propargyl group-grafted poly(arylpiperidinium) copolymer ionomer Monomers diphenylethane (1.0252 g, 5.625 mmol), terphenyl (3.885 g, 16.875 mmol), and 1-methyl-4-piperidone (2.8005 g, 24.750 mmol) were added to a 100 mL reactor, and dichloromethane (DCM, 18 mL) was added and stirred to dissolve the monomers. After cooling the solution to 1 °C, a mixture of trifluoroacetic acid (TFA, 2.7 mL) and trifluoromethanesulfonic acid (TFSA, 18 mL) was slowly added to the solution and stirred for 12 hours to obtain a viscous solution. The viscous solution was poured into 500 mL of distilled water for precipitation, washed several times with deionized water, and dried in an oven at 70 °C for 24 hours to produce solid poly(diphenyl-co-terphenyl N-methylpiperidine) polymer (PDTM) (yield: 95.3%).

[0054] Next, the prepared PDTM (7.247 g) was dissolved in dimethyl sulfoxide (100 mL) to obtain a clear polymer solution. Potassium carbonate (5.4 g) and propargyl bromide (0.5579 g) were then added to the polymer solution and stirred continuously at room temperature for 24 hours. Iodomethane (CHI, 4.6 g) was then added to the polymer solution, and the mixture was allowed to react at room temperature in a dark room for 24 hours to form a quaternary piperidinium salt. The mixture was then precipitated in 500 mL of ethyl acetate, filtered, washed several times with deionized water, and dried in a vacuum oven at 45°C for 24 hours to prepare a solid propargyl-grafted poly(arylpiperidinium) copolymer ionomer, designated PDTP-Pr-10 (graft ratio 10%, Synthesis Example 1).

[0055] In addition, poly(arylpiperidinium) copolymer ionomers grafted with propargyl groups were prepared by the same method as in Synthesis Example 1, but the graft ratios were adjusted to 30% and 50% by titrating the propargyl bromide content at 30% and 50% during the reaction. These were named PDTP-Pr-30 (Synthesis Example 2) and PDTP-Pr-50 (Synthesis Example 3), respectively (Example 2).

[0056] [Synthesis Examples 4 to 6] Preparation of poly(arylpiperidinium) copolymer ionomers grafted with propargyl groups Poly(arylpiperidinium) copolymer ionomers grafted with lopargyl groups were produced by the same method as in Synthesis Examples 1 to 3, except that triptycene, biphenyl, and 9,9'-dimethylfluorene were used instead of diphenylethane and terphenyl in Synthesis Examples 1 to 3 as monomers. These were named Trip-PFBP-Pr-10 (grafting rate 10%, Synthesis Example 4), Trip-PFBP-Pr-30 (grafting rate 30%, Synthesis Example 5), and Trip-PFBP-Pr-50 (grafting rate 50%, Synthesis Example 6), respectively.

[0057] [Production Examples 1 to 6] Production of anion exchange membranes crosslinked from propargyl group-grafted poly(arylpiperidinium) copolymer ionomers The propargyl-grafted poly(arylpiperidinium) copolymer ionomers obtained in Synthesis Examples 1 to 6 were dissolved in dimethyl sulfoxide to form a 5 wt% polymer solution. The polymer solution was then filtered through a PTFE filter (pore size 1 μm), cast onto a glass plate, and dried in a vacuum oven at 80°C for 24 hours. The resulting transparent film was then peeled off. The dried film was then heat-treated in a dark, vacuum environment at 170°C for 120 to 240 minutes to obtain crosslinked films. These films were named x-PDTP-Pr-10 (Preparation Example 1), x-PDTP-Pr-30 (Preparation Example 2), x-PDTP-Pr-50 (Preparation Example 3), x-Trip-PFBP-Pr-10 (Preparation Example 4), x-Trip-PFBP-Pr-30 (Preparation Example 5), and x-Trip-PFBP-Pr-50 (Preparation Example 6), respectively.

[0058] The obtained I-form membrane was immersed in a 1M NaOH aqueous solution at 60°C for 24 hours to convert the counter ions to OH.- The resulting mixture was washed several times with ultrapure water and dried to produce the desired crosslinked anion exchange membrane.

[0059] [Production Example 7] Production of a membrane electrode assembly (MEA) having a cross-linked structure. A catalyst containing Trip-PFBP-Pr-m, a poly(arylpiperidinium) copolymer ionomer grafted with propargyl groups, was sprayed onto a PDTP-Pr-x anion exchange membrane (m and x are the grafting rate and crosslinking degree, respectively, 10%, 30%, or 50%) to form a catalyst-coated membrane (CCM). The membrane electrode assembly was heat-treated at 170°C for 120 to 240 minutes in a dark, vacuum environment to initiate the trimerization and coupling reactions, followed by the crosslinking reaction. The resulting I-form membrane electrode assembly was immersed in a 1M KOH aqueous solution at 60°C for 24 hours to convert the counter ions to OH. - The resulting mixture was washed several times with ultrapure water and dried to produce a membrane electrode assembly (MEA) having a cross-linked structure.

[0060] Comparative Example 1: Preparation of propargyl group-free poly(arylpiperidinium) copolymer ionomer and anion exchange membrane A poly(diphenyl-co-terphenyldimethylpiperidinium) copolymer ionomer was synthesized by the same method as in Synthesis Example 1, except that propargyl bromide was not used as a reactant. An anion exchange membrane was then produced from the ionomer by the same method as in Synthesis Example 1, and the membrane was named PDTP.

[0061] [Comparative Example 2] Preparation of poly(arylpiperidinium) copolymer ionomer containing no propargyl groups A triptycene poly(fluorene-co-biphenyldimethylpiperidinium) copolymer ionomer was synthesized by the same method as in Synthesis Example 4, except that propargyl bromide was not used as a reactant. An anion exchange membrane was then prepared from the ionomer by the same method as in Synthesis Example 4, and the resulting membrane was named Trip-PFBP.

[0062] [Test example] Test data such as mechanical properties, water content, expansion rate, and fuel cell performance of the anion exchange membranes manufactured from the manufacturing examples and comparative examples of the present invention were measured and evaluated according to the method described in Korean Patent Publication No. 10-2021-0071810, a prior application filed by the inventors of the present invention.

[0063] First, FIG. 1 shows the poly(arylpiperidinium) copolymer ionomers Trip-PFBP-Pr-m series and PDTP-Pr-m series (m is 10, 30, 50) to which propargyl groups have been grafted, obtained in Synthesis Examples 1 to 6 of the present invention. 1 The 1 H NMR spectrum was shown.

[0064] As shown in Figure 1, the characteristic peak of methylene hydrogen from the propargyl group appeared around 4.5 ppm, indicating that the grafting reaction was successful. The grafting rate was calculated as the integral ratio between the methylene hydrogen atom around 4.5 ppm and the aromatic hydrogen atom around 7.0-7.8 ppm.

[0065] FIG. 2 also shows (A) the water content and (B) the expansion rate of the anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series (m is 10, 30, 50) crosslinked after heat treatment of Preparation Examples 1 to 6 of the present invention at 170°C for 0, 120, and 240 minutes, respectively. It can be seen that the water content and expansion rate decrease rapidly depending on the composition of the crosslinked structure and the crosslinking time.

[0066] In addition, FT-IR analysis was performed to confirm the progress of the crosslinking reaction in the crosslinked anion exchange membrane series obtained in Preparation Examples 1 to 6 of the present invention. Figure 3 shows graphs analyzing the degree of crosslinking of the x-PDTP-Pr-50 anion exchange membrane obtained in Preparation Example 3 of the present invention at different heat treatment times [(A) FT-IR spectra of the x-PDTP-Pr-50 anion exchange membranes obtained at different heat treatment times, (B) propargyl groups remaining in the x-PDTP-Pr-50 anion exchange membranes obtained at different heat treatment times (calculated by integrating the propargyl groups in the FT-IR spectra)].

[0067] As can be seen in Figure 3(A), 2120 cm -1 The absorption peak around 1000 is due to the stretching vibration of alkyne, and the intensity of the absorption peak decreases with increasing heat treatment time, which means that the propargyl group is consumed during the heat treatment process.

[0068] 3(B) shows that when the heat treatment time is less than 80 minutes, most of the propargyl groups remain unreacted, but when the heat treatment time exceeds 120 minutes, about 70% of the propargyl groups react. This means that the crosslinking reaction has proceeded successfully. Therefore, the critical heat treatment time is 120 minutes or more, and in the present invention, heat treatment is preferably performed for 120 to 240 minutes.

[0069] FIG. 4 shows images of the contact angles of the crosslinked anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series (m is 10, 30, and 50) prepared in Preparation Examples 1 to 6 of the present invention after heat treatment at 170°C for 120 minutes, as well as the PDTP and Trip-PFBP prepared in Comparative Examples 1 and 2. It can be seen that the water contact angle increases as the degree of crosslinking increases, indicating increased hydrophobicity.

[0070] 5 shows thermogravimetric analysis (TGA) graphs (m is 10, 30, 50) of the Trip-PFBP-Pr-m series and PDTP-Pr-m series obtained from Synthesis Examples 1 to 6 of the present invention (before heat treatment) and the anion exchange membranes x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series crosslinked after heat treatment of Production Examples 1 to 6 at 170°C for 120 minutes [(A) Trip-PFBP-Pr-10 and x-Trip-PFBP-Pr-10, (B) Trip- (C) Trip-PFBP-Pr-50 and x-Trip-PFBP-Pr-50; (D) PDTP-Pr-10 and x-PDTP-Pr-10; (E) PDTP-Pr-30 and x-PDTP-Pr-30; (F) PDTP-Pr-50 and x-PDTP-Pr-50]. It can be seen that the crosslinked anion exchange membranes obtained after heat treatment have superior thermal stability compared to the copolymer ionomers before heat treatment.

[0071] 6 shows the CO3 of the anion exchange membranes of the x-Trip-PFBP-Pr-m series and x-PDTP-Pr-m series (m is 10, 30, 50) crosslinked after heat treatment of Production Examples 1 to 6 of the present invention at 170°C for 0, 120, and 240 minutes, respectively. 2- The graph shows the conductivity (at 30°C) of the polymer, and the conductivity tends to decrease as the crosslinking time increases. In particular, it was found that the conductivity decreased rapidly after 240 minutes of crosslinking time by heat treatment. Therefore, it was confirmed that a crosslinking time of 120 to 240 minutes is preferable to ensure good conductivity.

[0072] FIG. 7 is a graph showing the peel strength of catalyst coating membranes for different types of copolymer ionomers and anion exchange membranes.

[0073] A control membrane electrode assembly (MEA) was fabricated using Trip-PFBP and PDTP obtained from Comparative Examples 1 and 2, and the 180° peel strength of the membrane electrode assembly was recorded using a universal testing machine (UTM).

[0074] As can be seen in Figure 7, the x-Trip-PFBP-Pr-x ionomer-based membrane electrode assembly achieved a much higher peel strength than the PDTP, Trip-PFBP (membrane, ionomer)-based membrane electrode assembly. In particular, the PDTP, x-Trip-PFBP-Pr-50-based membrane electrode assembly achieved a peel strength of 1.15 N mm, which is approximately twice that of the PDTP, Trip-PFBP-based membrane electrode assembly. -1 The high peel strength of the membrane electrode assembly suggests that the interaction between the catalyst layers is stronger. In other words, it was confirmed that the presence of a cross-linked structure can effectively improve the stability of the catalyst layer of the membrane electrode assembly.

[0075] Figure 8 also shows electrochemical stability data for the catalyst layers analyzed using a rotating disk electrode (RDE) test [transmission electron microscope images, average nanoparticle size, and linear scan voltammogram (LSV) measurements of the oxygen reduction reaction (ORR) for catalysts with different ionomers: (Figure 8A) Trip-PFBP, (Figure 8B) x-Trip-PFBP-10, (Figure 8C) x-Trip-PFBP-30, and (Figure 8D) x-Trip-PFBP-50].

[0076] After the durability test, the half-wave potential of the Trip-PFBP, Pt / C catalyst decreased from 0.683 V to 0.843 V. This was attributed to the loss of ionomer and the agglomeration of catalyst particles. To verify this, the catalyst micromorphology was observed using high-resolution transmission electron microscopy. After the durability test, the Pt particles aggregated to larger sizes. Specifically, the average particle size of the Trip-PFBP, Pt / C catalyst increased from 3.7 nm to 4.4 nm after the short durability test, suggesting poor stability. In contrast, the x-Trip-PFBP-Pr-m ionomer-based catalyst exhibited much more stable ORR LSV performance. The half-wave potential degradation was less than 11 mV. Meanwhile, Pt particle agglomeration was also significantly suppressed. Specifically, the average particle sizes of the x-Trip-PFBP-Pr-10, 30, and 50 ionomer-based catalysts increased from 3.36 to 3.62 nm (Figure 8B), from 3.17 to 3.41 nm (Figure 8C), and from 3.37 to 3.46 nm, respectively, which were much smaller than those of the PFBP-based catalyst (from 3.7 to 4.4 nm). This indicates that the crosslinked structure can fix the catalyst particles and stabilize the energy element.

[0077] FIG. 9 shows the fuel cell performance depending on the crosslinking degree of the copolymer ionomer and the anion exchange membrane.

[0078] The x-Trip-PFBP-Pr-10 and x-Trip-PFBP-Pr-30 ionomer-based fuel cells achieved 1.0 W cm without pressure doubling. -2 A maximum power density (PPD) of 0.502 W cm was achieved, which is higher than that of the x-Trip-PFBP-Pr-50 ionomer-based fuel cell (PPD 0.502 W cm). -2 ) is twice that of x-Trip-PFBP-Pr-10 and x-Trip-PFBP-Pr-30. This improvement in maximum power density is due to the high ionic conductivity of x-Trip-PFBP-Pr-10 and x-Trip-PFBP-Pr-30. In addition, x-PDTP-Pr-10 AEM-based fuel cells exhibit superior PPD performance compared to x-PDTP-Pr-30 and x-PDTP-Pr-50 due to their high water unit (WU) and conductivity.

[0079] FIG. 10 also shows a graph of the in-situ durability measurements of a fuel cell based on the x-PDTP-Pr-10 anion exchange membrane with asymmetric copolymer ionomer.

[0080] A 1,000-hour long-term stability test showed that the HFR of the fuel cell could be recovered after the refilling process. This suggests that the ohmic loss is caused by reasons other than chemical degradation of the membrane and ionomer (e.g., carbonation problems or uneven water distribution). These results suggest that improving the interaction between the AEM and the catalyst layer is an effective way to extend the life of anion exchange membrane fuel cells.

[0081] Figure 11 also shows the water electrolysis performance (linear scan voltammograms, LSV) and resistance (potentiostatic electrochemical impedance spectroscopy, PEIS) as a function of the crosslinking degree, temperature, and alkali composition of the copolymer ionomer.

[0082] The x-Trip-PFBP-Pr-10 ionomer-based AEMWE exhibited a thermal conductivity of 22.58 M ω cm -2 Low R ohm and 12.28 mΩ cm -2 R charge 14.34A cm in 1M KOH solution -2 The highest current density (11.9 A cm) was achieved using x-Trip-PFBP-Pr-30 ionomer at 2.0 V. -2 The decrease in the current (@2.0 V) is believed to be due to the low water absorption capacity of the positive electrode ionomer when a dry cathode is used. In this case, an asymmetric ionomer was used for the water electrolysis performance and durability tests. The positive electrode ionomers used were x-Trip-PFBP-Pr-10 and x-Trip-PFBP-Pr-30, respectively. By using the asymmetric ionomer, a current of 15.17 A cm was achieved at 80 °C. -2 The current density increased with increasing R ohm and Rcharge The AEMWE driven by concentrated alkaline solution exhibited enhanced conductivity (0.01M KOH 66mΩ cm -2 Vs. 1M KOH 23mΩ cm -2 R charge ) and electrochemical activity (0.01M KOH 79mΩ cm -2 Vs. 1M KOH 10mΩ cm -2 R charge ) shows a higher current density. Nevertheless, the AEMWE performance operated in 0.1 M KOH solution is still far superior.

[0083] In addition, Fig. 12 shows the results of the experiments using 1M KOH solution at 60°C and different current densities (0.5 A cm -2 , 1.0cm -2 , 1.5A cm -2 ) shows the in-situ durability test results of the negative electrolysis-based x-PDTP-Pr-10 anion exchange membrane measured under the conditions of

[0084] As can be seen in Figure 12, 0.5A cm -2 The AEMWE operated at 1000 Hz exhibited a low initial voltage of 1.63 V and a low initial voltage of 88 μV h -1 The voltage drop rate was 1.0 A cm. -2 The initial voltage of the AEMWE increases to 1.70 V and 98 μV h -1 The voltage drop rate was as low as 100 kJ / s, which indicates excellent stability.

[0085] 1.5A cm -2 This is a very severe condition for the long-term operation of an AEMWE, as it generates a large amount of oxygen bubbles in a short time and destroys the catalyst layer. However, the AEMWE using the catalyst layer obtained from Preparation Example 7 of the present invention achieved a current of 1.5 A cm. -2The AEMWE was able to operate for 1,000 hours at room temperature. More importantly, the AEMWE operated under these harsh conditions also exhibited excellent faradaic efficiency of over 95% during the test, demonstrating the gas robustness of the membrane electrode assembly. These results suggest that stabilizing the catalyst layer by thermal bridging is a promising method to enhance the performance and stability of AEMWEs.

Claims

1. A propargyl group-grafted poly(arylpiperidinium) copolymer ionomer having a repeating unit represented by the following <Chemical Formula 1>. <Chemical formula 1> 【Chemistry 1】 (In the above Chemical Formula 1, Aryl is two or more different compounds selected from compounds represented by the following structural formulas: 【Chemistry 2】

2. (I) as a monomer, (a) two or more different compounds selected from compounds represented by the following structural formulas: 【Transformation 3】 and (b) dissolving 1-methyl-4-piperidone in an organic solvent to form a solution; (II) slowly adding a strong acid catalyst to the solution, stirring and reacting to obtain a viscous solution; (III) precipitating, washing and drying the viscous solution to obtain a solid polymer; (IV) adding and reacting potassium carbonate, propargyl bromide, and an excess amount of halomethane to a polymer solution prepared by dissolving the solid polymer in an organic solvent to form a quaternary piperidinium salt grafted with a propargyl group; and (V) precipitating, washing, and drying the mixed solution.

3. 3. The method for producing a propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to claim 2, wherein the organic solvent in step (I) is a halogen-based solvent selected from the group consisting of dichloromethane, chloroform, dichloroethane, dibromomethane, and tetrachloroethane.

4. 3. The method for producing a propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to claim 2, wherein the strong acid catalyst in step (II) is trifluoroacetic acid, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoro-1-propanesulfonic acid, perfluoropropionic acid, heptafluorobutyric acid, or a mixture thereof.

5. 3. The method for preparing a propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to claim 2, wherein the organic solvent in step (IV) is N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, or dimethylformamide.

6. 3. The method for preparing a propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to claim 2, wherein the halomethane in step (IV) is fluoromethane, chloromethane, bromomethane, or iodomethane.

7. An anion exchange membrane crosslinked from the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to claim 1.

8. (i) dissolving the propargyl group-grafted poly(arylpiperidinium) copolymer ionomer according to claim 1 in an organic solvent to form a polymer solution; (ii) casting the polymer solution onto a glass plate and heating it to remove the organic solvent to obtain a dried film; (iii) heat-treating the dried film to obtain a cross-linked film; and (iv) The obtained membrane was washed with 1M NaHCO 3 or a method for producing an anion exchange membrane, comprising the steps of treating the anion exchange membrane with 1 M NaOH, washing the anion exchange membrane with ultrapure water several times, and drying the treated anion exchange membrane.

9. 9. The method for producing an anion exchange membrane according to claim 8, wherein the concentration of the polymer solution is 2 to 30% by weight.

10. 10. The method for manufacturing an anion exchange membrane according to claim 8, wherein the heat treatment in step (iii) is performed on the dried membrane in a dark and vacuum environment at 160 to 180°C for 120 to 240 minutes, thereby initiating a trimerization reaction and a coupling reaction and then completing a crosslinking reaction.

11. An alkaline fuel cell comprising the anion exchange membrane of claim 7.

12. A water electrolysis device comprising the anion exchange membrane according to claim 7.

13. A supercapacitor comprising the anion exchange membrane of claim 7.

14. A carbon dioxide reduction device comprising the anion exchange membrane according to claim 7.

15. An oxidation-reduction flow battery comprising the anion exchange membrane of claim 7.

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