阅读说明：本技术 制造燃料电池电解质隔膜的方法和由此制造的电解质隔膜 (Method of manufacturing fuel cell electrolyte membrane and electrolyte membrane manufactured thereby ) 是由 朴仁釉 高载准 洪普基 于 2019-10-21 设计创作，主要内容包括：公开制造包括抗氧化剂的电解质隔膜的方法。方法能够包括形成包括去离子水、第一离聚物分散溶液和抗氧化剂的第一分散液,并且形成包括第一分散液和第二离聚物分散溶液的第二分散液。(Disclosed is a method of manufacturing an electrolyte separator including an antioxidant. The method can include forming a first dispersion including deionized water, a first ionomer dispersion solution, and an antioxidant, and forming a second dispersion including the first dispersion and a second ionomer dispersion solution.)

1. A method of manufacturing an electrolyte membrane for a fuel cell, the method comprising the steps of:

forming a first dispersion comprising a first ionomer dispersion solution and an antioxidant; and is

Forming a second dispersion comprising the first dispersion and a second ionomer dispersion solution.

2. The method of claim 1, wherein the first dispersion comprises deionized water.

3. The method of claim 2, wherein said forming said first dispersion comprises first dispersing said deionized water, said first ionomer dispersion solution, and said antioxidant.

4. The method of claim 3, wherein the forming the first dispersion comprises at least one of a stirring process and an ultrasonic treatment process using a magnetic bar.

5. The method of claim 4, wherein the first dispersing is performed for about 1 to 60 minutes.

6. The method of claim 1, wherein the forming the second dispersion comprises a second dispersion.

7. The method of claim 6, wherein the second dispersing is performed for about 1 to 10 minutes.

8. The method of claim 6, wherein the second dispersing is performed by stirring after the first dispersion is added to the second ionomer dispersion solution.

9. The method of claim 1, wherein a time for the second dispersion is less than a time for the first dispersion.

10. The method of claim 1 wherein the composition of the first ionomer dispersion solution is the same as the composition of the second ionomer dispersion solution.

11. The method of claim 10, wherein the weight of the second ionomer dispersion solution in the second dispersion is greater than the weight of the first ionomer dispersion solution.

12. The method of claim 10 wherein the mixing ratio of components in the composition of the first ionomer dispersion solution is the same as the mixing ratio of components in the composition of the second ionomer dispersion solution.

13. The method of claim 1, wherein the weight ratio of the first ionomer dispersion solution and the second ionomer dispersion solution in the second dispersion is about 1:5 to 1: 5000.

14. The method of claim 1, wherein the antioxidant comprises a cerium nitrate (Ce (NO) hexahydrate salt selected from₃)₃·6H₂O), cerium oxide (CeO)₂) And Samarium Doped Ceria (SDC).

15. The method of claim 1 wherein at least one of the first ionomer dispersion solution and the second ionomer dispersion solution comprises a solvent component comprising deionized water, n-propanol, or a combination thereof.

16. The method of claim 1 wherein at least one of the first ionomer dispersion solution and the second ionomer dispersion solution comprises a perfluorinated sulfonic acid ionomer.

17. The method of claim 1, wherein at least one of the first ionomer dispersion solution and the second ionomer dispersion solution has an Equivalent Weight (EW) of about 700 to 1200.

18. The method of claim 1, further comprising, after the forming the second dispersion:

manufacturing an electrolyte separator by coating a release film with the second dispersion liquid; and is

Heat-treating the electrolyte separator.

19. An electrolyte membrane for a fuel cell, which is manufactured by the method according to claim 1.

Technical Field

The present invention relates to a method of manufacturing an electrolyte membrane for a fuel cell and an electrolyte membrane manufactured thereby.

Background

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) are generally configured to include a membrane-electrode assembly (MEA) including electrodes including an anode and a cathode and an ionomer-based electrolyte membrane to thereby generate electricity.

In particular, in order to increase chemical durability, an antioxidant in the form of a salt or an oxide has been added to an ionomer dispersion in a predetermined amount, thereby forming a polymer electrolyte membrane. To effectively prevent oxidation, an antioxidant containing cerium (Ce) may be included in the electrolyte separator. Such antioxidants may be added directly to the ionomer solution, or may be added to a solvent such as water, and then mixed.

Cerium ions mixed in the form of a salt by conventional methods can very easily move to different locations in an electrolyte membrane in a fuel cell operating environment, or migrate to an electrode (anode or cathode). Therefore, the concentration of cerium added to the electrolyte separator may vary. Therefore, the development of an electrolyte separator including an antioxidant in the form of an oxide has been actively conducted recently. For example, polymer electrolyte separators have been manufactured by dispersing an antioxidant in an ionomer solution, and then performing casting or bar coating. However, since the pH of the ionomer solution is in the acidic range of about 3 to 4, the added antioxidant may react with the ionomer solution in an acidic atmosphere during the dispersion of the antioxidant, and thus may be dissolved (or released). Therefore, the antioxidant exists in a form that can be easily moved, and can be dissolved during the operation of the fuel cell, which is undesirable.

Disclosure of Invention

In a preferred aspect, a method of manufacturing an electrolyte separator is provided, in which dissolution of an antioxidant can be suppressed during dispersion of the antioxidant in an acidic ionomer solution or during stirring, thereby increasing acid resistance of the electrolyte separator.

Also provided is a method of manufacturing an electrolyte separator, in which an antioxidant dispersion liquid having high dispersibility can be formed, thereby suppressing the dissolution of the antioxidant and uniformly distributing the antioxidant without agglomerating particles in the electrolyte separator.

Also provided is a method of manufacturing an electrolyte separator, in which the time required to form an ionomer dispersion including an antioxidant can be effectively reduced, thereby shortening the process time for manufacturing the electrolyte separator and improving the process efficiency.

The invention is not limited by the foregoing, and other specific details of the invention are set forth in the detailed description and drawings.

In one aspect, there is provided a method of manufacturing an electrolyte membrane for a fuel cell, which may include: forming a first dispersion that is an aqueous composition comprising a first ionomer dispersion solution and an antioxidant; and forming a second dispersion comprising the first dispersion and a second ionomer dispersion solution. The first dispersion may additionally comprise deionized water, or may be a water composition or an aqueous composition.

Preferably, forming the first dispersion may include first dispersed deionized water, a first ionomer dispersion solution, and an antioxidant. For example, forming the first dispersion may include at least one of a stirring process and an ultrasonic treatment process using a magnetic bar. Deionized water is preferably used to provide the aqueous composition. In certain preferred embodiments, at least a portion of the total water present in the first dispersion is deionized water, e.g., wherein at least about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95% of the water present in the first dispersion is deionized water.

The first dispersion may suitably be carried out for about 1 minute to 60 minutes.

Preferably, forming the second dispersion may include second dispersing. The second dispersion may suitably be carried out for about 1 minute to 10 minutes. For example, the second dispersion may be performed by stirring after the first dispersion is added to the second ionomer dispersion solution.

Preferably, the time for performing the second dispersion may be less than the time for the first dispersion.

The composition of the first ionomer dispersion solution may be the same as or different from the composition of the second ionomer dispersion solution. Preferably, the composition of the first ionomer dispersion solution is the same as the composition of the second ionomer dispersion solution. For example, the statement that the composition of the first ionomer dispersion solution is the same as the composition of the second ionomer dispersion solution means that the type or composition of the components in the first ionomer dispersion solution is the type or composition of the components in the composition of the second ionomer dispersion solution, which may not limit the content (e.g., mixing ratio) of the respective components. Preferably, the weight of the second ionomer dispersion solution in the second dispersion may be greater than the weight of the first ionomer dispersion solution.

Preferably, the mixing ratio of the components in the composition of the first ionomer dispersion solution may be the same as the mixing ratio of the components in the composition of the second ionomer dispersion solution.

The weight ratio of the first ionomer dispersion solution and the second ionomer dispersion solution in the second dispersion may suitably be in the range of about 1:5 to 1: 5000.

The antioxidant may suitably comprise a cerium nitrate (Ce (NO) salt selected from hexahydrate₃)₃·6H₂O), cerium oxide (CeO)₂) And Samarium Doped Ceria (SDC). However, the present invention is not limited thereto, and any antioxidant may be used as long as it is in the form of an oxidation-preventing oxide.

At least one of the first ionomer dispersion solution and the second ionomer dispersion solution may suitably include a solvent component, which may include deionized water, n-propanol, or a combination thereof.

At least one of the first ionomer dispersion solution and the second ionomer dispersion solution may suitably comprise a perfluorinated sulfonic acid ionomer.

The Equivalent Weight (EW) of at least one of the first ionomer dispersion solution and the second ionomer dispersion solution may suitably be in the range of about 700 to about 1200.

The method of the present invention may additionally comprise, after forming the second dispersion: manufacturing an electrolyte separator by coating a release film with the second dispersion liquid; and heat-treating the electrolyte separator.

Also provided is an electrolyte membrane for a fuel cell, which is manufactured by the method described herein.

Other aspects of the invention are disclosed below.

According to various exemplary embodiments of the present invention, a method of manufacturing an electrolyte membrane for a fuel cell may include a double dispersion process using an ionomer dispersion solution in a stepwise manner, thereby increasing acid resistance of an antioxidant included in the electrolyte membrane and finally improving durability of the fuel cell.

In addition, the electrolyte membrane manufactured by such a double dispersion process may be configured such that the antioxidant included in the electrolyte membrane may be uniformly and homogeneously distributed without agglomerated particles. Therefore, the performance of the fuel cell including the electrolyte membrane can be additionally improved.

In addition, the stirring time for dispersing the antioxidant during the process of manufacturing the electrolyte separator can be minimized, thereby reducing the total process time for manufacturing the electrolyte separator having improved performance and increased productivity.

The effects of the present invention are not limited to the foregoing, and should be understood to include all effects reasonably expected from the following description.

Drawings

Fig. 1 illustrates an exemplary process of manufacturing an electrolyte membrane for a fuel cell according to an exemplary embodiment of the present invention;

FIG. 2 illustrates the formation of an exemplary first dispersion in an exemplary embodiment of the invention;

FIG. 3 illustrates the formation of an exemplary second dispersion in an exemplary embodiment of the invention;

fig. 4 illustrates an exemplary process of manufacturing an exemplary electrolyte membrane for an exemplary fuel cell according to an exemplary embodiment of the present invention;

FIG. 5 shows an exemplary electrolyte separator applied on a release film in an exemplary embodiment of the invention;

FIG. 6 is a graph showing the comparison results of the particle agglomeration sizes of the dispersions in examples 1 and 2 of the present invention and comparative examples 1 and 2; and

fig. 7 is a graph showing the results of the acid resistance test of examples 1 and 2 of the present invention and comparative examples 1 and 2.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention and how they may be carried into effect will become apparent by reference to the following detailed description of exemplary embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various forms. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art to which the invention pertains, and the present invention will only be defined by the scope of the appended claims. Throughout the drawings, the same reference numerals will be used to refer to the same or like elements.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in the sense commonly understood by one of ordinary skill in the art to which this invention belongs. Furthermore, unless explicitly defined otherwise, commonly used predefined terms are not to be interpreted ideally or excessively formally.

Furthermore, the terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In this specification, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "having," and the like, when used in this specification, specify the presence of stated elements, features, numbers, steps, and/or operations, but do not preclude the presence or addition of one or more other elements, features, numbers, steps, and/or operations. Here, the term "and/or" includes each of the mentioned items as well as all combinations of one or more thereof.

Further, 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. In contrast, 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.

Unless otherwise indicated, all numbers, values, and/or representations indicating amounts of components, reaction conditions, polymer compositions, and mixtures used herein are to be considered approximate, including various uncertainties and the like affecting measurements that occur substantially at the time these values are obtained, and thus are to be understood as modified in all instances by the term "about. Further, when a range of values is disclosed in this specification, the range is continuous and includes all values from the minimum value to the maximum value of the range unless otherwise indicated. Further, when such ranges fall within integer values, all integers including the minimum to maximum values are included unless otherwise indicated.

Further, unless specifically stated or otherwise apparent from the context, the term "about" as used herein is understood to be within the normal tolerance of the art, e.g., within 2 standard deviations of the mean. "about" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. All numerical values provided herein are modified by the term "about," unless the context clearly dictates otherwise.

Hereinafter, a detailed description of the present invention will be given with reference to the accompanying drawings.

Fig. 1 is a flowchart illustrating an exemplary process of manufacturing an exemplary electrolyte membrane for an exemplary fuel cell according to an exemplary embodiment of the present invention.

As shown in fig. 1, a method of manufacturing an exemplary electrolyte separator including an exemplary antioxidant may include forming a first dispersion including water or a water composition (such as deionized water as described above), a first ionomer dispersion solution, and an antioxidant, for example, by mixing and dispersing the water or the water composition (such as deionized water as described above), the first ionomer dispersion solution, and the antioxidant (S10), and forming a second dispersion including the first dispersion and the second ionomer dispersion solution, for example, by adding and dispersing the first dispersion to the second ionomer dispersion solution (S20).

In particular, in the method of manufacturing an electrolyte membrane for a fuel cell according to an exemplary embodiment of the present invention, in order to increase the dispersibility of the antioxidant and suppress the dissolution thereof in an acidic solution or increase the acid resistance, a double dispersion process (S10 and S20) using an ionomer dispersion solution in a stepwise manner may be included. By the double dispersion process, the antioxidant can be uniformly and homogeneously distributed without agglomeration of particles in the final electrolyte separator. In addition, the stirring time for dispersing the antioxidant through the double dispersion process can be minimized, and thus the total processing time required to manufacture the electrolyte separator can be reduced, thereby improving productivity.

Subsequently, separate dispersion processes (S10 and S20) are illustrated in fig. 2 and 3. Fig. 2 shows the formation of a first dispersion liquid (S10 of fig. 1) in an exemplary embodiment of the present invention, and fig. 3 shows the formation of a second dispersion liquid (S20 of fig. 1) in an exemplary embodiment of the present invention.

As shown in fig. 2, the formation of the first dispersion (S10) may be performed in the following manner: wherein, for example, a water composition (such as deionized water 10), a first ionomer dispersion solution 11, and an antioxidant 15 may be mixed, and the resulting mixed solution may be dispersed, thereby obtaining a first dispersion 100.

In particular, in order to uniformly disperse the antioxidant 15, the stirring process may be performed for a sufficient period of time, whereby the antioxidant 15 may be dispersed in the first ionomer dispersion solution 11. For example, the formation of the first dispersion 100 may be performed for 1 minute to 60 minutes. Thereby, the first dispersion 100 in which the antioxidant 15 can be uniformly dispersed (i.e., the dispersibility is improved) can be formed. Thus, the dispersion process may include, for example, at least one of a stirring process using a magnetic rod and an ultrasonic treatment process.

In the formation of the first dispersion (S10), the antioxidant 15 may preferably contain cerium (Ce). The antioxidant 15 may include a compound selected from, for example, cerium nitrate hexahydrate (Ce (NO)₃)₃·6H₂O), cerium oxide (CeO)₂) And Samarium Doped Ceria (SDC). However, the present invention is not limited thereto, and any antioxidant may be used as long as it is in the form of an oxidation-preventing oxide.

In the formation of the first dispersion (S10), the first ionomer dispersion solution 11 may include a solvent component including, for example, deionized water, n-propanol, or a combination thereof. Further, the first ionomer dispersion solution 11 may include, for example, perfluorinated sulfonic acid ionomer. Specifically, the antioxidant 15 in the form of an oxide may be added to the perfluorinated sulfonic acid ionomer dispersion solution as the first ionomer dispersion solution 11, and then stirring may be performed using a magnetic bar so as to achieve uniform distribution (S10).

In the formation of the first dispersion (S10), the Equivalent Weight (EW) of the first ionomer dispersion solution 11 may be in the range of about 700 to about 1200.

Subsequently, as shown in fig. 3, the formation of the second dispersion (S20) may be performed in the following manner: wherein, for example, the first dispersion 100 may be added to the second ionomer dispersion solution 20 and then dispersed, thereby obtaining the second dispersion 200.

In particular, the formation of the second dispersion (S20) may be performed, for example, for about 1 minute to 10 minutes. Further, the time for dispersion during the formation (S20) of the second dispersion liquid 200 may be shorter than the time for dispersion during the formation (S10) of the first dispersion liquid 100, but the present invention is not limited thereto.

The dispersion time during the formation (S20) of the second dispersion liquid 200 is a time period required to disperse the first dispersion liquid 100 that has been added to the second ionomer dispersion solution 20. Further, the time for dispersion during the formation of the first dispersion 100 (S10) may be a time period required to disperse the deionized water 10, the first ionomer dispersion solution 11, and the antioxidant 15.

The dispersion during the formation of the second dispersion liquid 200 (S20) may be performed by stirring after the first dispersion liquid 100 is added to the second ionomer dispersion solution 20. In particular, the dispersion process may include stirring using a magnetic bar.

In the formation of the second dispersion (S20), the second ionomer dispersion solution 20 may include a solvent component including, for example, deionized water, n-propanol, or a combination thereof. The second ionomer dispersion solution 20 may also include perfluorinated sulfonic acid ionomer. The EW of the second ionomer dispersion solution 20 may be in the range of about 700 to about 1200.

In the method of manufacturing an electrolyte membrane for a fuel cell according to an exemplary embodiment of the present invention, the composition included in the first ionomer dispersion solution (11 of fig. 2) during the formation (S10) of the first dispersion may be the same as the composition included in the second ionomer dispersion solution (20 of fig. 3) during the formation (S20) of the second dispersion. Here, in the second dispersion, the weight of the second ionomer dispersion solution 20 may be greater than the weight of the first ionomer dispersion solution 11.

Further, the mixing ratio of the components in the composition of the first ionomer dispersion solution 11 may be the same as the mixing ratio of the components in the composition of the second ionomer dispersion solution 20. For example, the first ionomer dispersion solution 11 and the second ionomer dispersion solution 20 may have the same composition (e.g., the same ionomer and the same solvent) and the same mixing ratio, but the present invention is not limited thereto.

In the method of manufacturing an electrolyte membrane for a fuel cell according to an exemplary embodiment of the present invention, the weight of the second ionomer dispersion solution 20 may be greater than the weight of the first ionomer dispersion solution 11, and particularly, for example, the weight ratio of the first ionomer dispersion solution 11 to the second ionomer dispersion solution 20 in the second dispersion may be in the range of about 1:5 to about 1: 5000. In particular, when the first ionomer dispersion solution 11 and the second ionomer dispersion solution 20 have the same composition and mixing ratio, the weight ratio of the first ionomer dispersion solution 11 during the formation of the first dispersion (S10) to the second ionomer dispersion solution 20 during the formation of the second dispersion (S20) may preferably be in the range of about 1:5 to 1:5000, or particularly in the range of about 1:10 to 1: 3000. Thereby, an electrolyte membrane for a fuel cell capable of suppressing the dissolution of the antioxidant 15 can be produced.

As shown in fig. 4 and 5, a method of manufacturing an exemplary electrolyte membrane for an exemplary fuel cell according to an exemplary embodiment of the present invention is described below. Fig. 4 is a flowchart illustrating a process of manufacturing an exemplary electrolyte separator according to an exemplary embodiment of the present invention, and fig. 5 is a conceptual diagram illustrating an electrolyte separator applied on a peeling film. For convenience of description, only the contents different from those described with respect to fig. 1 to 3 are described.

As shown in fig. 4, the method of manufacturing an exemplary electrolyte membrane for a fuel cell according to an exemplary embodiment of the present invention may further include coating a release film with the second dispersion after the formation of the second dispersion (S20) (S30). For example, the second dispersion may be cast or bar-coated, thereby obtaining a polymer electrolyte membrane in which the antioxidant is dispersed in the ionomer solution by stirring for a sufficient period of time so as to achieve uniform dispersion.

Further, the method of manufacturing the electrolyte separator may further include heat-treating the electrolyte separator (S40). Here, the heat treatment may be performed in an oven at a temperature of about 100 to 250 ℃ for about 5 minutes, but the present invention is not limited thereto.

As shown in fig. 5, after the coating process (S30 of fig. 4), the electrolyte membrane 201 applied on the peeling film 30 may be formed. As shown in fig. 5, the electrolyte separator 201 may be formed into a flat surface by passing its surface opposite to the surface in contact with the release film 30 through the applicator 33.

The electrolyte membrane 201 may be formed of the aforementioned second dispersion liquid (200 of fig. 3), and thus the electrolyte membrane 201 may include the antioxidant 15. Meanwhile, the electrolyte separator 201 may also be manufactured by additionally performing an additional process (e.g., drying). For example, the electrolyte separator 201 may be formed by additionally performing a heat treatment process (S40) after the coating process (S30).

For example, as an electrolyte separator manufactured by the method of manufacturing an electrolyte separator for a fuel cell as described above, the acid resistance and dispersibility of the contained antioxidant can be increased by a double dispersion process using an ionomer dispersion solution in a stepwise manner. Accordingly, the electrolyte membrane may exhibit additional increased durability and performance, thereby improving the driving efficiency of the fuel cell as well as the output performance thereof.

Examples of the invention

The present invention will be better understood by the following examples and comparative examples. However, the following examples are set forth to illustrate the present invention and should not be construed as limiting the scope of the present invention.

Preparation examples

Preparation examples

a) Deionized water was mixed with a small amount of an ionomer dispersion solution (first ionomer dispersion solution), and then samarium-doped ceria (SDC) as an antioxidant was added thereto, followed by stirring and ultrasonic treatment (primary dispersion), thereby preparing a first dispersion including an antioxidant having improved dispersibility. Here, the mixing ratio of the deionized water, the ionomer dispersion solution, and the antioxidant was 1:0.04:0.015 (weight), and stirring and ultrasonic treatment were performed for 10 minutes. In the present invention, the ionomer dispersion liquid that is mixed in a small amount at the time of primary dispersion of the antioxidant is the same as the ionomer solution used for manufacturing the electrolyte separator. Here, the weight ratio of the mixed materials in the ionomer dispersion is deionized water to n-propanol to ionomer 1:0.835: 0.459.

b) Next, a second dispersion liquid (secondary dispersion) in which the antioxidant is uniformly dispersed in the perfluorosulfonic acid ionomer dispersion solution (second ionomer dispersion solution) is prepared. Here, the dispersion time was 2 minutes. The first dispersion liquid including the antioxidant prepared by the primary dispersion was mixed with a large amount of ionomer dispersion liquid and then stirred for about 2 minutes to obtain an ionomer dispersion liquid including the antioxidant, and the first dispersion liquid including the antioxidant and the ionomer dispersion liquid were mixed in a weight ratio of 1: 15. The second ionomer dispersion solution has the same composition and mixing ratio as the first ionomer dispersion solution in step a).

c) Applying the solution obtained in step b) on a release film, thereby manufacturing a polymer electrolyte separator including an antioxidant. In particular, a polymer electrolyte separator is manufactured through a rod coating process using an ionomer dispersion including an antioxidant. Furthermore, the final heat treatment was performed in an oven at a temperature of 170 ℃ for about 5 minutes.

Comparative preparation example

The polymer electrolyte separator was manufactured in the following manner: wherein a dispersion obtained by mixing an antioxidant with deionized water was added to an ionomer dispersion solution, and then dispersed by stirring without adding a small amount of the ionomer dispersion solution in the step a) (formation of the first dispersion) of the preparation example. Here, the dispersion is performed for 120 minutes.

In the antioxidant dispersion liquid of the comparative preparation example, deionized water, an ionomer dispersion solution, and an antioxidant were mixed at a weight ratio of 1:0:0.015, and stirring and ultrasonic treatment were performed for 10 minutes. The small amount of ionomer dispersion solution mixed at the time of primary dispersion of the antioxidant in the preparation example was the same solution as the large amount of ionomer dispersion solution used for manufacturing the electrolyte separator. Here, the mixing ratio of deionized water, n-propanol and ionomer was 1:0.835:0.459 (by weight).

The antioxidant dispersion liquid prepared by the primary dispersion was mixed with the ionomer dispersion solution in a weight ratio of 1:15 and then stirred for about 120 minutes, thereby preparing an ionomer dispersion solution including an antioxidant, and then a polymer electrolyte separator was manufactured from the ionomer dispersion solution through a bar coating process. Furthermore, the final heat treatment was performed in an oven at 170 ℃ for about 5 minutes.

Test examples

TABLE 1

Examples 1 and 2

The electrolyte separators of examples 1 and 2 were manufactured by a double dispersion process (including steps a) and b) in the preparation examples), and table 1 shows primary dispersion (performed or not) and secondary dispersion time (2 minutes). In example 1, SDC antioxidant (SDC-600) heat-treated at a temperature of 600 ℃ was added and used in the process of manufacturing the electrolyte separator. In example 2, SDC antioxidant (SDC-800) heat treated at a temperature of 800 ℃ was added and used.

Comparative examples 1 and 2

As shown in table 1, in comparative examples 1 and 2, a small amount of ionomer dispersion solution was not added during primary dispersion of the antioxidant, and secondary dispersion was performed for 120 minutes after the primary dispersion. In comparative example 1, SDC antioxidant (SDC-600) heat-treated at a temperature of 600 ℃ was added and used in the process of manufacturing an electrolyte separator. In comparative example 2, SDC antioxidant (SDC-800) heat treated at 800 ℃ was added and used.

Evaluation example 1 analysis of particle agglomeration size

Evaluation method

Particle dispersibility was measured by analyzing the particle agglomerate size of the dispersions including the antioxidant in examples and comparative examples. Specifically, the particle agglomeration size was analyzed based on the change in the particle size distribution of the antioxidants of the examples and comparative examples using a dynamic light scattering particle size analyzer (Horiba), nanoparticles SZ-100. Due to the higher dispersion of SDC antioxidant, the particle agglomerate size decreased and, in addition, a low precipitation rate of the antioxidant particles was observed upon visual inspection.

Evaluation results

Fig. 6 is a graph showing the comparison results of the particle agglomeration sizes of the dispersions of examples 1 and 2 and comparative examples 1 and 2.

Referring to fig. 6, particle agglomeration sizes of the SDC antioxidants in examples 1 and 2 are shown, in which the antioxidants were heat-treated at temperatures of 600 ℃ (SDC-600) and 800 ℃ (SDC-800), and primary antioxidant dispersion was performed with the addition of a small amount of ionomer dispersion solution.

In contrast, the particle agglomeration sizes of the SDC antioxidants in comparative examples 1 and 2 are shown, in which the antioxidants were heat-treated at temperatures of 600 ℃ (SDC-600) and 800 ℃ (SDC-800), and primary antioxidant dispersion was performed without adding a small amount of ionomer dispersion solution. In particular, when comparative example 1 and comparative example 2 were compared, the particle agglomerate size greatly increased with the increase in heat treatment temperature.

As shown in fig. 6, the particle agglomerate size in examples 1 and 2 was significantly lower than that in comparative examples 1 and 2. On the other hand, particle agglomeration was very significant in comparative examples 1 and 2. This means that the secondary dispersion time can be increased in order to sufficiently ensure the dispersibility of the antioxidant in the ionomer solution.

Evaluation example 2 acid resistance test results

Evaluation method

The use examples and comparative examples include an antioxidantSpecifically, the electrolyte membrane prepared in each of the preparation examples and the comparative preparation examples was cut to a predetermined size (5cm × 5cm), and the acid resistance test was performed in an acidic atmosphere simulating the actual operating conditions of the polymer electrolyte membrane fuel cell₂SO₄) In the solution, the temperature was maintained at 80 ℃ for about 30 minutes, and washed with deionized water, after which the content of cerium ions remaining in the electrolyte membrane was measured using an X-ray photoelectron spectrometer. As the content of cerium ions in the electrolyte separator increases, the acid resistance of the antioxidant may be higher. When the acid resistance is reduced, the SDC antioxidant can be largely dissolved in the acidic ionomer dispersion solution and thus released into the sulfuric acid solution, whereby the residual cerium ion content can be reduced.

Evaluation results

Fig. 7 is a graph showing the results of the acid resistance test of examples 1 and 2 and comparative examples 1 and 2.

Referring to fig. 7, the electrolyte separator including SDC antioxidant in examples 1 and 2 was in 0.5M sulfuric acid (H)₂SO₄) The solution was maintained for 30 minutes, in which the antioxidant was heat-treated at temperatures of 600 ℃ (SDC-600) and 800 ℃ (SDC-800), and primary antioxidant dispersion was performed with the addition of a small amount of ionomer dispersion solution, after which the remaining cerium contents were about 72.8% and 94.5% with respect to 100% of the initial cerium content.

In contrast, the electrolyte separator including the SDC antioxidant of comparative examples 1 and 2 was at 0.5M sulfuric acid (H)₂SO₄) The solution was maintained for 30 minutes, in which the antioxidant was heat-treated at temperatures of 600 ℃ (SDC-600) and 800 ℃ (SDC-800), and primary antioxidant dispersion was performed without adding a small amount of ionomer dispersion solution, after which the remaining cerium content was about 15.3% and 20.0% with respect to 100% of the initial cerium content. This means that the antioxidant is very largely dissolved (or released) in the acidic ionomer dispersion solution during the dispersion of the added antioxidant.

Therefore, as shown in the results of fig. 7, when the antioxidant is primarily dispersed using a small amount of ionomer dispersion solution, the initial dispersibility of the antioxidant dispersion can be maximized, and thus the dispersion time can be minimized when mixing with a large amount of ionomer dispersion solution. Finally, the acid resistance of the antioxidant in the final electrolyte membrane can be significantly increased.

Although various exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications are possible without departing from the scope and spirit of the present invention as disclosed in the appended claims, and that such modifications should not be construed as being apart from the technical ideas or essential features of the present invention.