Electrolyte membrane for high-temperature polymer electrolyte membrane fuel cell comprising polymer electrolyte having novel structure

Abstract

The present invention relates to an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell comprising a polymer electrolyte having a novel structure. Specifically, the present invention discloses an electrolyte membrane comprising a polymer electrolyte having a novel structure, and a high-temperature polymer electrolyte membrane fuel cell comprising the electrolyte membrane.

Description

Technical Field

[0001] The present disclosure relates to an electrolyte membrane including a polymer electrolyte having a new structure and a high-temperature polymer electrolyte membrane fuel cell including the same. Background Art

[0002] According to the operating temperature, polymer electrolyte membrane fuel cells can be classified into low-temperature polymer electrolyte membrane fuel cells operating at 60°C to 80°C and high-temperature polymer electrolyte membrane fuel cells operating at 120°C to 200°C.

[0003] Low-temperature polymer electrolyte membrane fuel cells have expensive electrolyte membranes and require a carbon monoxide emission reduction device configured to prevent catalyst poisoning and a water controller configured to precisely maintain the water content of the electrolyte membrane.

[0004] Since high-temperature polymer electrolyte membrane fuel cells operate at high temperatures, they operate in a dry environment without water. Therefore, high-temperature polymer electrolyte membrane fuel cells can solve the problems of water flooding in the electrodes and complex humidification systems.

[0005] High-temperature polymer electrolyte membrane fuel cells mainly use polymers based on phosphoric acid-doped polybenzimidazole (PBI) as electrolyte membranes. Polymers based on polybenzimidazole have a high glass transition temperature and excellent thermal stability and physicochemical stability. However, polymers based on polybenzimidazole have limitations in that they are difficult to process due to their low solubility and their mechanical properties deteriorate significantly when the phosphoric acid content increases. In addition, phosphate groups are released at high temperatures, causing problems of electrode poisoning and system corrosion.

[0006] The information disclosed in the background of the present invention is only for enhancing the understanding of the general background of the present invention and may not be regarded as an admission or an implication in any form that the information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0007] Aspects of the present disclosure aim to provide an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell having excellent thermal stability and chemical stability.

[0008] Aspects of the present disclosure aim to provide an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell that is easy to process due to its high solubility.

[0009] Aspects of the present disclosure aim to provide an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell that facilitates mass production.

[0010] Aspects of the present disclosure aim to provide an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell with reduced release of proton-conducting groups.

[0011] The objectives of the present disclosure are not limited to the foregoing. Through the following description, the objectives of the present disclosure will be clearly understood and achieved by the means described in the present invention.

[0012] Aspects of the present disclosure aim to provide an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell, the electrolyte membrane including a polymer electrolyte having proton conductivity, wherein the polymer electrolyte may include a main chain and side chains, the main chain including at least one of fluorene or biphenyl, and the side chains including a nitrogen-containing functional group and a proton-conducting functional group connected to the nitrogen-containing functional group. Preferably, the main chain may include fluorene and biphenyl.

[0013] The main chain may not include any bonds other than carbon-carbon bonds.

[0014] The proton-conducting functional group may include dihydrogen phosphate anion (H2PO4 - ).

[0015] The nitrogen-containing functional group may include a quaternary ammonium cation.

[0016] The nitrogen-containing functional group and the proton-conducting functional group may be connected by electrostatic attraction.

[0017] The polymer electrolyte may be represented by Chemical Formula 1 below.

[0018] [Chemical Formula 1]

[0019]

[0020] In Chemical Formula 1, R1, R2, R3, and R4 each include hydrogen, an alkyl group having 1 to 3 carbon atoms, or -(CH2) x -R5·H2PO4 - (where x is a number from 1 to 6); at least one selected from R1, R2, R3, and R4 includes -(CH2) x -R5·H2PO4- (where x is a number from 1 to 6), R5 includes -NR6R7R8 + , R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms, or two of R6, R7, and R8 are connected to each other to form a ring having 2 to 6 carbon atoms and the remaining one includes an alkyl group having 1 to 3 carbon atoms; and m and n satisfy 0 < m < 100 and m + n = 100.

[0021] In Chemical Formula 1, at least two selected from R1, R2, R3, and R4 may include -(CH2) x -NH3+ ·H2PO4 - (where x is a number from 1 to 6).

[0022] The polymer electrolyte can be represented by the following Chemical Formula 2.

[0023] [Chemical Formula 2]

[0024]

[0025] In Chemical Formula 2, R5 includes -NR6R7R8 + , R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms, or two of them are connected to each other to form a ring having 2 to 6 carbon atoms and the remaining one includes an alkyl group having 1 to 3 carbon atoms; and m1 and n1 satisfy 0 < m1 < 100 and m1 + n1 = 100.

[0026] The polymer electrolyte can be represented by the following Chemical Formula 3.

[0027] [Chemical Formula 3]

[0028]

[0029] In Chemical Formula 3, R5 includes -NR6R7R8 + , R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms, or two of them are connected to each other to form a ring having 2 to 6 carbon atoms and the remaining one includes an alkyl group having 1 to 3 carbon atoms; and m2 and n2 satisfy 0 < m2 < 100 and m2 + n2 = 100.

[0030] When the polymer electrolyte is subjected to thermogravimetric analysis (TGA) at 200 °C, the polymer electrolyte can have a remaining amount of 90 wt% or more.

[0031] The electrolyte membrane can have a proton conductivity of 200 mS / cm or more at 180 °C.

[0032] Another aspect of the present disclosure provides a high-temperature polymer electrolyte membrane fuel cell, which includes the above electrolyte membrane, an anode disposed on one surface of the electrolyte membrane, and a cathode disposed on the other surface of the electrolyte membrane.

[0033] The high-temperature polymer electrolyte membrane fuel cell can operate at 120 °C to 200 °C.

[0034] The high-temperature polymer electrolyte membrane fuel cell can operate at a relative humidity of 50% or less. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above features and other features of the present disclosure will now be described in detail with reference to certain exemplary embodiments of the present disclosure shown in the accompanying drawings. The drawings are described herein by way of illustration only, and thus do not limit the present disclosure, and wherein:

[0036] Figure 1 Shows a high-temperature polymer electrolyte membrane fuel cell according to an exemplary embodiment of the present disclosure;

[0037] Figure 2 Shows the H of the starting material represented by Chemical Formula 4-1 1 results of NMR;

[0038] Figure 3 Shows the H of the intermediate material represented by Chemical Formula 4-2 1 results of NMR;

[0039] Figure 4 Shows the visual observation results of an electrolyte membrane including a polymer electrolyte represented by Chemical Formula 4-3;

[0040] Figure 5 Shows the H of the starting material represented by Chemical Formula 5-1 1 results of NMR;

[0041] Figure 6 Shows the H of the intermediate material represented by Chemical Formula 5-2 1 results of NMR;

[0042] Figure 7 Shows the visual observation results of an electrolyte membrane including a polymer electrolyte represented by Chemical Formula 5-3;

[0043] Figure 8 Shows the results of thermogravimetric analysis of the polymer electrolytes according to Examples 1 and 2;

[0044] Figure 9 Shows the strain-stress curve of the sample according to Example 1;

[0045] Figure 10 Shows the strain-stress curve of the sample according to Example 2; and

[0046] Figure 11 Shows the measurement results of the proton conductivity of the electrolyte membranes according to Examples 1 and 2.

[0047] It is understood that the drawings are not necessarily drawn to scale and present a somewhat simplified representation of the various features illustrating the basic principles of the present disclosure. The specific design features of the invention disclosed herein (including, for example, specific dimensions, orientations, positions, and shapes) will be determined in part by the particular intended application and use environment.

[0048] In the accompanying drawings, reference numerals in some of the drawings throughout the drawings refer to the same or equivalent components of the present invention. Detailed Description of the Invention

[0049] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the present invention will be described in conjunction with the exemplary embodiments of the present disclosure, it should be understood that this specification is not intended to limit the present invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only the exemplary embodiments of the present disclosure, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the present invention as defined in the appended claims.

[0050] From the following exemplary embodiments in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will be more clearly understood. However, the present disclosure is not limited to the embodiments disclosed herein and may be modified into different forms. These embodiments are provided to fully explain the present disclosure and to convey the spirit of the present disclosure to those skilled in the art.

[0051] Throughout the drawings, the same reference numerals will indicate the same or similar elements. For the sake of clarity of the present disclosure, the dimensions of the structures are depicted as larger than their actual dimensions. It will be understood that although terms such as "first", "second", etc. may be used herein to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present disclosure, the "first" element discussed below may be referred to as the "second" element. Similarly, the "second" element may also be referred to as the "first" element. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form.

[0052] It will be further understood that when the terms "comprises", "comprising", "has", etc. are used in this specification, the presence of the specified features, wholes, steps, operations, elements, components, or combinations thereof is indicated, but the presence or addition of one or more other features, wholes, steps, operations, elements, components, or combinations thereof is not excluded. Also, it will be understood that when an element such as a layer, film, region, or sheet is referred to as being "on" another element, it can be directly on the other element, or intervening elements may be present therebetween. Similarly, when an element such as a layer, film, region, or sheet is referred to as being "under" another element, it can be directly under the other element, or intervening elements may be present therebetween.

[0053] Unless otherwise specified, all numerical values, values and / or representations used herein to denote amounts of components, reaction conditions, polymer compositions, and mixtures shall be considered approximate values, including the various uncertainties affecting measurements, which inherently occur in obtaining such values, etc., and shall thus be understood to be modified by the term "about" in all cases. In addition, when a numerical range is disclosed in this specification, the range is continuous and includes all values from the minimum value to the maximum value of the said range, unless otherwise stated. Further, when such a range relates to integer values, all integers from the minimum value to the maximum value are included, unless otherwise specified.

[0054] Figure 1 A high-temperature polymer electrolyte membrane fuel cell according to an exemplary embodiment of the present disclosure is shown.

[0055] The high-temperature polymer electrolyte membrane fuel cell may be a polymer electrolyte membrane fuel cell operating at a high temperature of about 120 °C to 200 °C. Alternatively, the high-temperature polymer electrolyte membrane fuel cell may be a polymer electrolyte membrane fuel cell operating at a relative humidity of about 50% or less.

[0056] The high-temperature polymer electrolyte membrane fuel cell has the same structure or principle as the existing low-temperature polymer electrolyte membrane fuel cell, but has advantages such as no water overflow at the anode and no need for a humidification system, etc.

[0057] The high-temperature polymer electrolyte membrane fuel cell may include an electrolyte membrane 10, an anode 20 disposed on one surface of the electrolyte membrane 10, and a cathode 30 disposed on the other surface of the electrolyte membrane 10.

[0058] The electrolyte membrane 10, anode 20, and cathode 30 are not limited in terms of shape, thickness, area, etc., and any type commonly used in the technical field to which the present disclosure pertains may be applied.

[0059] The electrolyte membrane 10 may include a polymer electrolyte having proton conductivity. Here, the proton conductivity may represent the ability to conduct or exchange protons (H + ) to move between the anode 20 and the cathode 30.

[0060] The polymer electrolyte may include a main chain and side chains connected to the main chain. The main chain may include at least one of fluorene or biphenyl. Preferably, the main chain may include fluorene and biphenyl. The side chains may include nitrogen-containing functional groups and proton-conducting functional groups connected to the nitrogen-containing functional groups.

[0061] The nitrogen-containing functional group may include a quaternary ammonium cation. For example, the quaternary ammonium cation may be arranged such that when any one of the hydrogens in the ammonium cation (NH4 + ) is a connection site, all the remaining hydrogens are replaced by methyl groups (-CH3).

[0062] The side chain may further include a linking group that connects the nitrogen-containing functional group to the main chain. The linking group is not particularly limited and may include, for example, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

[0063] The proton-conducting functional group may include dihydrogen phosphate anion (H2PO4 - ).

[0064] The polymer electrolyte may include a compound represented by the following Chemical Formula 1.

[0065] [Chemical Formula 1]

[0066]

[0067] In Chemical Formula 1, R1, R2, R3, and R4 each include hydrogen, an alkyl group having 1 to 3 carbon atoms, or -(CH2) x -R5·H2PO4 - (where x is a number from 1 to 6), and at least one of them may include -(CH2) x -R5·H2PO4 - (where x is a number from 1 to 6). Here, “·” may represent an electrostatic attraction between R5 and the dihydrogen phosphate anion (H2PO4 - ).

[0068] R5 includes -NR6R7R8 + , where R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms, or two of R6, R7, and R8 may be connected to each other to form a ring having 2 to 6 carbon atoms and the remaining one may include an alkyl group having 1 to 3 carbon atoms.

[0069] For example, R5 may include Here, may indicate the connection site.

[0070] Moreover, in Chemical Formula 1, m and n may satisfy 0 < m < 100 and m + n = 100.

[0071] In a preferred example of the polymer electrolyte, at least two selected from R1, R2, R3, and R4 include -(CH2) x -R5·H2PO4 - (where x is a number from 1 to 6).

[0072] Any embodiment of the polymer electrolyte may include a compound represented by the following Chemical Formula 2.

[0073] [Chemical Formula 2]

[0074]

[0075] In Chemical Formula 2, R5 includes -NR6R7R8 + , where R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms, or two of them may be connected to each other to form a ring having 2 to 6 carbon atoms and the remaining one may include an alkyl group having 1 to 3 carbon atoms, and m1 and n1 satisfy 0 < m1 < 100 and m1 + n1 = 100. In Chemical Formula 2, "------" may represent the electrostatic attraction between R5 and the dihydrogen phosphate anion (H2PO4 - ).

[0076] Another exemplary embodiment of the polymer electrolyte may include a compound represented by the following Chemical Formula 3.

[0077] [Chemical Formula 3]

[0078]

[0079] In Chemical Formula 3, R5 includes -NR6R7R8 + , where R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms, or two of them may be connected to each other to form a ring having 2 to 6 carbon atoms and the remaining one may include an alkyl group having 1 to 3 carbon atoms, and m2 and n2 satisfy 0 < m2 < 100 and m2 + n2 = 100. In Chemical Formula 3, "------" may represent the electrostatic attraction between R5 and the dihydrogen phosphate anion (H2PO4 - ).

[0080] The polymer electrolyte is characterized in that the main chain does not contain any bonds other than carbon-carbon bonds. Specifically, the main chain can be synthesized by a polycondensation reaction of a strong acid and can consist only of carbon-carbon bonds. If the main chain contains an aryl ether bond (Csp2-O) or a benzylic C-H bond having a low binding energy, it can decompose in a high-temperature environment. Since the polymer electrolyte according to the exemplary embodiment of the present disclosure does not include the above bonds, it has excellent thermal stability and chemical stability.

[0081] In addition, the polymer electrolyte is a composite of a fluorene-based kinked main chain and a branched-chain structure and has a large free volume (the space between atoms), so it has high solubility in aprotic solvents. Existing phosphoric acid-doped polybenzimidazole-based polymers have problems of low solubility and difficulty in processing. The polymer electrolyte according to the exemplary embodiment of the present disclosure has high solubility and excellent processability.

[0082] In addition, the polymer electrolyte can be synthesized by polycondensing monomers at room temperature for about 3 hours in the presence of an acid catalyst, which is conducive to mass production.

[0083] In addition, the polymer electrolyte may include an ion pair structure in which a proton-conducting functional group is connected to a nitrogen-containing functional group. The interaction of this ion pair structure can maintain a higher attractive force than the existing phosphoric acid-doped polybenzimidazole-based polymer, thus solving the problem of phosphoric acid release at high temperatures.

[0084] Each of the anode 20 and the cathode 30 may include a catalyst and an ionomer.

[0085] The catalyst may include any material commonly used in the technical field to which the present disclosure pertains. For example, the catalyst may include a noble metal catalyst such as platinum (Pt), a non-noble metal catalyst, or an alloy catalyst thereof.

[0086] The ionomer may include any material commonly used in the technical field to which the present disclosure pertains. For example, the ionomer may include a phosphoric acid-doped polybenzimidazole-based polymer or the same polymer electrolyte as the above electrolyte membrane 10.

[0087] A better understanding of the present disclosure can be obtained through the following examples. These examples are only illustrative of the present disclosure and are not to be construed as limiting the scope of the present disclosure.

[0088] Example 1

[0089] The starting material represented by the following Chemical Formula 4-1 was synthesized in the following manner. Prepare 9,9-dimethylfluorene (1 g, 5.15 mmol), biphenyl (7.14 g, 46.33 mmol), and 7-bromo-1,1,1-trifluoroheptan-2-one (13.99 g, 56.62 mmol) as monomers. Prepare trifluoromethanesulfonic acid (TFSA) (77.25 g, 514.75 mmol) as a catalyst. Based on 100 parts by weight of the monomers, prepare 23 parts by weight of dichloromethane (DCM) as a reaction solvent, and add 100 parts by weight of the monomers and the catalyst to the reaction solvent to prepare a reactant. The reactant was maintained at about 5 °C for about 30 minutes, and then reacted at room temperature (about 20 °C to 25 °C) for about 3 hours and 30 minutes to synthesize the starting material. The reaction product was precipitated in 1,300 ml of methanol, washed several times with methanol, and dried in a vacuum oven at about 40 °C to obtain the starting material.

[0090] [Chemical Formula 4-1]

[0091]

[0092] Using the above starting material, the intermediate material represented by Chemical Formula 4-2 was synthesized in the following manner.

[0093] Dissolve 100 parts by weight of the starting material (3 g, 7.75 mmol) in 10 parts by weight of dimethylacetamide (DMAc), and then add trimethylamine (2.14 ml, 27.11 mmol) to prepare the reactant. React the reactant at room temperature (about 20 °C to 25 °C) for about 24 hours to synthesize the intermediate material. Precipitate the reaction result in 500 ml of tetrahydrofuran (THF), wash it several times with acetone, and dry it in a vacuum oven at about 60 °C to obtain the intermediate material.

[0094] [Chemical formula 4-2]

[0095]

[0096] Figure 2 Shows the H 1 NMR results of the starting material represented by Chemical formula 4-1. Figure 3 Shows the H 1 NMR results of the intermediate material represented by Chemical formula 4-2.

[0097] Refer to Figure 2 , a phenyl peak of the polymer main chain is observed at 7.0 ppm to 8.0 ppm, and an alkyl peak of the side chain is observed at 1.0 ppm to 3.5 ppm.

[0098] Refer to Figure 3 , the conversion rate is determined to be 100% by the integration ratio (2:9) of the CH2(11’) peak near the modifiable position at the side chain end and the peak (12) caused by the newly introduced functional group.

[0099] Using the above intermediate material, an electrolyte membrane including a polymer electrolyte represented by the following Chemical formula 4-3 is prepared in the following manner.

[0100] Dissolve 0.4 g of the intermediate material in dimethyl sulfoxide (DMSO), cast it on a glass plate of 8 cm x 8 cm, and dry it in a drying oven at about 60 °C for about 8 hours to prepare a membrane. Place the membrane in a phosphoric acid solution with a concentration of about 85 wt% and let it stand in an oven at about 60 °C for about 75 hours. Remove the phosphoric acid on the membrane surface with a polytetrafluoroethylene membrane to obtain an electrolyte membrane with a thickness of about 40 μm.

[0101] [Chemical formula 4-3]

[0102]

[0103] Figure 4 Shows the visual observation results of the electrolyte membrane including the polymer electrolyte represented by Chemical formula 4-3.

[0104] Example 2

[0105] Prepare 9,9-bis(6-bromohexyl)-9H-fluorene (3 g, 6.09 mmol), biphenyl (0.94 g, 6.09 mmol), and 1,1,1-trifluoroacetone (1.50 g, 13.41 mmol) as monomers. Prepare trifluoromethanesulfonic acid (TFSA) (18.29 g, 13.41 mmol) as a catalyst. Based on 100 parts by weight of the monomers, prepare 20 parts by weight of dichloromethane (DCM) as a reaction solvent, and add 100 parts by weight of the monomers and the catalyst to the reaction solvent to prepare a reactant. Keep the reactant at about 5 °C for about 1 hour and 30 minutes, and then react at room temperature (about 20 °C to 25 °C) for about 30 minutes to synthesize the starting material. Precipitate the reaction product in 700 ml of methanol, wash it several times with methanol, and dry it in a vacuum oven at about 40 °C to obtain the starting material.

[0106] [Chemical formula 5-1]

[0107]

[0108] Using the above starting material, synthesize an intermediate material represented by the following Chemical formula 5-2 in the following manner.

[0109] Dissolve 100 parts by weight of the starting material (3 g, 6.74 mmol) in 10 parts by weight of dimethylacetamide (DMAc), and then add trimethylamine (1.85 ml, 23.58 mmol) to prepare a reactant. React the reactant at room temperature (about 20 °C to 25 °C) for about 24 hours to synthesize the intermediate material. Precipitate the reaction product in 500 ml of tetrahydrofuran (THF), wash it several times with acetone, and dry it in a vacuum oven at about 60 °C to obtain the intermediate material.

[0110] [Chemical formula 5-2]

[0111]

[0112] Figure 5 The H 1 NMR results of the starting material represented by Chemical formula 5-1 are shown. Figure 6 The H 1 NMR results of the intermediate material represented by Chemical formula 5-2 are shown.

[0113] Reference Figure 5 , a phenyl peak of the polymer main chain is observed at 7.0 ppm to 8.0 ppm, and an alkyl peak of the side chain is observed at 1.0 ppm to 3.5 ppm.

[0114] Refer to Figure 6, the conversion rate was determined to be 100% by the integration ratio (2:9) of the CH2(12’) peak near the modifiable position at the side chain end and the peak (13) caused by the newly introduced functional group.

[0115] Using the above intermediate material, an electrolyte membrane including a polymer electrolyte represented by the following Chemical Formula 5-3 was prepared in the following manner.

[0116] 0.4 g of the intermediate material was dissolved in dimethyl sulfoxide (DMSO), cast on an 8 cm x 8 cm glass plate, and dried in an oven at about 60 °C for about 8 hours to prepare a membrane. The membrane was placed in a phosphoric acid solution having a concentration of about 85 wt% and left standing in an oven at about 60 °C for about 75 hours. The phosphoric acid on the membrane surface was removed with a polytetrafluoroethylene membrane, thereby obtaining an electrolyte membrane having a thickness of about 40 μm.

[0117] [Chemical Formula 5-3]

[0118]

[0119] Figure 7 Visual observation results of the electrolyte membrane including the polymer electrolyte represented by Chemical Formula 5-3 are shown.

[0120] Thermogravimetric analysis (TGA) was performed on the polymer electrolytes according to Examples 1 and 2. Specifically, thermogravimetric analysis was performed on the intermediate materials obtained in Examples 1 and 2. Since the only difference between the intermediate material and the polymer electrolyte is the presence or absence of a proton-conducting functional group, the results of the intermediate material are substantially the same as those of the polymer electrolyte.

[0121] Each sample was heated from room temperature to about 120 °C at a rate of about 20 °C / min and held for about 10 minutes to remove residual water. After that, the sample was cooled to about 60 °C at a rate of about 20 °C / min, then heated to about 800 °C at a rate of about 10 °C / min in a nitrogen atmosphere, and the weight change of the sample was measured. The results are as Figure 8 shown.

[0122] Figure 8 The results of the thermogravimetric analysis of the polymer electrolytes according to Examples 1 and 2 are shown. Referring to this, in Example 1, the remaining amount was about 95% at about 208.5 °C, and the remaining amount was about 90% at about 246.4 °C. In Example 2, the remaining amount at 239.3 °C was about 95%, and the remaining amount at about 258.9 °C was about 90%. Based on the results of the thermogravimetric analysis in Examples 1 and 2, the remaining amount was 90 wt% or more at 200 °C, showing excellent thermal stability. Here, the "remaining amount" can indicate the ratio of the initial mass of the sample to the mass at the corresponding temperature.

[0123] Film specimens were prepared from the starting and intermediate materials of Example 1, and thereafter the mechanical properties of each specimen were measured. After attaching a 250 N load cell to the LLOYD UTM LS1 device, each specimen cut according to ASTM D 638 Type V was fixed thereto. The elongation rate was set at 5 mm / min. Three samples were measured for each specimen, and the strain-stress curve, Young's modulus, and the average and standard deviation values of elongation were determined.

[0124] Figure 9 The strain-stress curves of the specimens according to Example 1 are shown. The mechanical properties of each specimen are shown in Table 1 below.

[0125] [Table 1]

[0126]

[0127] Film specimens were prepared from the starting and intermediate materials of Example 2, and thereafter the mechanical properties of each specimen were measured. After attaching a 250 N load cell to the LLOYD UTM LS1 device, each specimen cut according to ASTM D 638 Type V was fixed thereto. The elongation rate was set at 5 mm / min. Three samples were measured for each specimen, and the strain-stress curve, Young's modulus, and the average and standard deviation values of elongation were determined.

[0128] Figure 10 The strain-stress curves of the specimens according to Example 2 are shown. The mechanical properties of each specimen are shown in Table 2 below.

[0129] [Table 2]

[0130]

[0131] Based on the above results, the intermediate material modified with quaternary ammonium cations shows high tensile strength and elongation.

[0132] The proton conductivities of the electrolyte membranes according to Examples 1 and 2 were measured. Each electrolyte membrane was made into a specimen of 0.5 cm x 3 cm and fixed to a 4-probe cell, and then its resistance was measured using electrochemical spectroscopy (SP-240, Bio Logic Science Instrument, France). Under the condition of 100% relative humidity with the cell placed in secondary distilled water, the resistance values depending on the temperature change from about 30 °C to 90 °C were measured and the proton conductivity was calculated using the following equation.

[0133] Proton conductivity (σ) [mS / cm] = d / R·S

[0134] Here, d is the distance between the electrodes, R is the resistance value, and S is the value obtained by multiplying the thickness of the sample by the width.

[0135] When the cell containing distilled water reached each temperature up to 180 °C, the resistance value was measured, and the resistance value was measured and recorded six times at each temperature.

[0136] Figure 11 The measurement results of the proton conductivity of the electrolyte membranes according to Examples 1 and 2 are shown. Referring thereto, Examples 1 and 2 showed a proton conductivity of 200 mS / cm or more at 180 °C.

[0137] A high-temperature polymer electrolyte membrane fuel cell was prepared by attaching electrodes including a platinum catalyst to both surfaces of the electrolyte membrane according to Example 1. The high-temperature polymer electrolyte membrane fuel cell was operated at 160 °C and 180 °C and its performance was measured. The results are shown in Table 3 below.

[0138] [Table 3]

[0139]

[0140] A high-temperature polymer electrolyte membrane fuel cell was prepared by attaching electrodes including a platinum catalyst to both surfaces of the electrolyte membrane according to Example 2. The high-temperature polymer electrolyte membrane fuel cell was operated at 160 °C and 180 °C and its performance was measured. The results are shown in Table 4 below.

[0141] [Table 4]

[0142]

[0143] According to the present disclosure, an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell having excellent thermal stability and chemical stability can be obtained.

[0144] According to the present disclosure, an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell that is easy to process due to its high solubility can be obtained.

[0145] According to the present disclosure, an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell that facilitates mass production can be obtained.

[0146] According to the present disclosure, an electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell having a reduced release of proton-conducting groups can be obtained.

[0147] The effects of the present disclosure are not limited to the above effects. It should be understood that the effects of the present disclosure include all effects that can be inferred from the description of the present disclosure.

[0148] The foregoing description of the test examples and specific exemplary embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. Exemplary embodiments were chosen and described in order to illustrate certain principles of the disclosure and its practical application so that others skilled in the art can make and utilize the various exemplary embodiments of the present invention and its various alternatives and modifications. The scope of the disclosure is intended to be defined by the appended claims and their equivalents.

Claims

1. An electrolyte membrane for a high-temperature polymer electrolyte membrane fuel cell, the electrolyte membrane comprising: A polymer electrolyte having proton conductivity, wherein the polymer electrolyte includes a main chain and side chains, the main chain includes at least one of fluorene or biphenyl, and the side chains include a nitrogen-containing functional group and a proton-conducting functional group connected to the nitrogen-containing functional group.

2. The electrolyte membrane according to claim 1, wherein the main chain does not contain any bonds other than carbon-carbon bonds.

3. The electrolyte membrane according to claim 1, wherein the proton conductive functional group comprises a dihydrogen phosphate anion (H2PO4 - ).

4. The electrolyte membrane according to claim 1, wherein the nitrogen-containing functional group contains a quaternary ammonium cation.

5. The electrolyte membrane according to claim 1, wherein the nitrogen-containing functional group and the proton-conducting functional group are connected by electrostatic attraction.

6. The electrolyte membrane according to claim 1, wherein the polymer electrolyte is represented by the following Chemical Formula 1: [Chemical Formula 1] In Chemical Formula 1, R1, R2, R3 and R4 each include hydrogen, an alkyl group having 1 to 3 carbon atoms or -(CH2) x -R5·H2PO4 - , where x is a number from 1 to 6, At least one selected from R1, R2, R3 and R4 includes -(CH2) x -R5·H2PO4 - , where x is a number from 1 to 6, R5 includes -NR6R7R8 + , R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms; or two of R6, R7, and R8 are connected to each other to form a ring having 2 to 6 carbon atoms, and the remaining one of R6, R7, and R8 includes an alkyl group having 1 to 3 carbon atoms; and m and n satisfy 0 < m < 100 and m + n = 100.

7. The electrolyte membrane according to claim 6, wherein in Chemical Formula 1, at least two selected from R1, R2, R3 and R4 include -(CH2) x -R5·H2PO4 - , where x is a number from 1 to 6.

8. The electrolyte membrane according to claim 1, wherein the polymer electrolyte is represented by the following Chemical Formula 2: [Chemical Formula 2] In Chemical Formula 2, R5 comprises -NR6R7R8 + , R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms; or two of R6, R7, and R8 are connected to each other to form a ring having 2 to 6 carbon atoms, and the remaining one of R6, R7, and R8 includes an alkyl group having 1 to 3 carbon atoms; and m1 and n1 satisfy 0 < m1 < 100 and m1 + n1 = 100.

9. The electrolyte membrane according to claim 1, wherein the polymer electrolyte is represented by the following Chemical Formula 3: [Chemical Formula 3] In Chemical Formula 3, R5 includes -NR6R7R8 + , R6, R7, and R8 each include an alkyl group having 1 to 3 carbon atoms; or two of R6, R7, and R8 are connected to each other to form a ring having 2 to 6 carbon atoms, and the remaining one of R6, R7, and R8 includes an alkyl group having 1 to 3 carbon atoms; and m2 and n2 satisfy 0 < m2 < 100 and m2 + n2 = 100.

10. The electrolyte membrane according to claim 1, wherein when the polymer electrolyte is subjected to thermogravimetric analysis (TGA) at 200 °C, the polymer electrolyte has a remaining amount of 90 wt% or more.

11. The electrolyte membrane according to claim 1, wherein the electrolyte membrane has a proton conductivity of 200 mS / cm or more at 180 °C.

12. A high-temperature polymer electrolyte membrane fuel cell, comprising: The electrolyte membrane according to claim 1; An anode disposed on one surface of the electrolyte membrane; And A cathode disposed on the other surface of the electrolyte membrane.

13. The high-temperature polymer electrolyte membrane fuel cell according to claim 12, wherein the high-temperature polymer electrolyte membrane fuel cell operates at 120 °C to 200 °C.

14. The high temperature polymer electrolyte membrane fuel cell according to claim 12, wherein the high temperature polymer electrolyte membrane fuel cell is operated at a relative humidity of 50% or less.

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