Antioxidants for fuel cells having high antioxidant capacity, electrolyte membranes and membrane-electrode assemblies comprising the same

Abstract

Disclosed are an antioxidant for a fuel cell having high antioxidant capacity, and an electrolyte membrane and a membrane-electrode assembly including the same, and more particularly, an antioxidant for a fuel cell having high dispersity and / or distribution and excellent antioxidant capacity, and a membrane-electrode assembly including the same. The antioxidant includes a metal oxide and a sulfur-containing organic compound adsorbed on the metal oxide, for example, an organic compound including a sulfinic acid anion group (R-SO2 ‑ ).

Description

TECHNICAL FIELD

[0001] The present application relates to an antioxidant for a fuel cell having high dispersity and / or distribution and excellent antioxidant ability, and an electrolyte membrane and a membrane-electrode assembly including the same. BACKGROUND

[0002] A proton exchange membrane fuel cell (PEMFC or polymer electrolyte membrane fuel cell) is a power generation device using hydrogen fuel, having the advantages of high energy efficiency, simple system configuration, and environmental friendliness. The proton exchange membrane fuel cell has recently received attention as an energy conversion device for environmentally friendly vehicles.

[0003] A reaction that generates electricity in a fuel cell occurs in a membrane-electrode assembly (MEA) composed of an electrolyte membrane based on a perfluorosulfonic acid (PFSA) ionomer and a negative electrode and a positive electrode. Hydrogen supplied to the negative electrode (oxidation electrode of the fuel cell) is separated into protons and electrons, the protons move to the positive electrode (which is a reduction electrode) through the membrane, and the electrons move to the positive electrode through an external circuit. In the positive electrode, oxygen molecules, protons, and electrons react together to generate electricity and heat, while water (H2O) is produced as a reaction byproduct at the same time.

[0004] As a reaction gas of the fuel cell, hydrogen gas and oxygen gas cross the electrolyte membrane, thereby promoting the generation of hydrogen peroxide (HOOH). Hydrogen peroxide generates highly reactive oxygen-containing radicals such as hydroxyl radicals (·OH) and peroxyl radicals (·OOH). These radicals attack the electrode and the ionomer binder in the perfluorinated sulfonic acid-based electrolyte membrane, resulting in chemical degradation of the membrane-electrode assembly, ultimately reducing the durability of the fuel cell.

[0005] As a technique to reduce chemical degradation, a method of adding various types of antioxidants has been proposed. Antioxidants are classified into primary antioxidants having a radical scavenger (or quencher) function and secondary antioxidants having a hydrogen peroxide decomposer function. These can be used alone or in combination.

[0006] Typical examples of the primary antioxidant can include cerium-based antioxidants such as cerium oxide (or cerium dioxide) and cerium (III) nitrate hexahydrate, and manganese-based antioxidants, while typical examples of the secondary antioxidant can include manganese-based antioxidants such as manganese oxide and the like, and transition metal catalysts such as platinum (Pt) and the like.

[0007] The ceria-based antioxidant used as a primary antioxidant is introduced in the form of nanoparticles or powder having a crystallite size of several nanometers or several tens of nanometers. Since the ceria-based antioxidant is generally prepared and then stored in the form of agglomerates, it must be dispersed before being added to the electrolyte membrane. Therefore, in order to increase the degree of dispersion and / or distribution, the surface of the antioxidant can be stabilized using a surfactant, but the active surface area of the antioxidant can be reduced, which can reduce the durability of the fuel cell. Thus, it is still necessary to develop an antioxidant having distribution stability and antioxidant ability through a large active site. SUMMARY

[0008] In preferred aspects, an antioxidant having distribution stability and further improved antioxidant ability, and an electrolyte membrane and electrolyte membrane-electrode assembly including the same are provided.

[0009] The objects of the present application are not limited to the above-mentioned objects, and will be clearly understood by the following description, and can be achieved by the means described in the claims and combinations thereof.

[0010] In one aspect, an antioxidant for a fuel cell is provided, which includes a metal oxide and an organic compound containing a sulfinate anion group (R-SO2 - ) and adsorbed on the metal oxide.

[0011] The metal oxide can be represented by the following Chemical Formula 1.

[0012] [Chemical Formula 1]

[0013] MO 2-δ

[0014] M can include one or more selected from the group consisting of transition metals and rare earth metals, and δ is an oxygen vacancy value that makes the metal oxide electrically neutral.

[0015] M can suitably include one or more selected from the group consisting of zirconium (Zr), cerium (Ce), samarium (Sm), gadolinium (Gd), and terbium (Tb).

[0016] The metal oxide can be supported on a support, and the support can include one or more selected from the group consisting of titanium dioxide (TiO2), silicon dioxide (silica, SiO2), ceria, ceria-zirconia, gadolinium-doped ceria, titanium oxide-supported ceria, and silicon dioxide-supported ceria.

[0017] The metal oxide can have a crystallite size of about 1 nm to 100 nm, about 5 nm to 80 nm, or about 10 nm to 50 nm.

[0018] The average particle size of the agglomerates of the metal oxide can be about 900 nm or less, about 500 nm or less, or about 100 nm or less.

[0019] The organic compound containing a sulfur element can suitably include formamidin sulfonic acid.

[0020] The mass ratio of the metal oxide and the organic compound containing a sulfur element can be about 10:0.1 to 10 or 10:0.5 to 4.

[0021] In another aspect, a method of manufacturing an antioxidant for a fuel cell is provided. The method can include preparing a mixture including a metal oxide and an organic compound containing sulfur such as a sulfinate anion group (R-SO2 - ), pulverizing the raw material, and heat-treating the pulverized material.

[0022] The raw material can be pulverized by dry milling.

[0023] The raw material can be pulverized at about 50 rpm to 1,000 rpm or about 100 rpm to 500 rpm.

[0024] The pulverized material can be heat-treated at a temperature of about 40°C to 250°C or a temperature of about 50°C to 150°C.

[0025] The pulverized material can be heat-treated for about 20 minutes to 15 hours or about 2 hours to 6 hours.

[0026] In an aspect, an electrolyte membrane including the antioxidant described herein is provided. The electrolyte membrane can suitably include about 0.05 wt% to 4 wt% or about 0.2 wt% to 1 wt% of the antioxidant, based on the total weight of the electrolyte membrane.

[0027] In another aspect, a membrane-electrode assembly including an electrolyte membrane, a positive electrode disposed on one side of the electrolyte membrane, and a negative electrode disposed on the other side of the electrolyte membrane, at least one of the electrolyte membrane, the positive electrode, and the negative electrode including the antioxidant described herein is provided.

[0028] According to various exemplary embodiments of the present application, the distribution stability of the antioxidant and the antioxidant ability can be improved.

[0029] According to various exemplary embodiments of the present application, the chemical durability of the electrolyte membrane and the membrane-electrode assembly can be improved, and the durability of a fuel cell including the electrolyte membrane and the membrane-electrode assembly can be extended.

[0030] Effects of the present application are not limited to the aforementioned and should be understood to include all effects that can be reasonably expected from the following description.

[0031] Other aspects of the present application are disclosed below. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 An exemplary antioxidant according to an exemplary embodiment of the present application is shown.

[0033] Figure 2 is a reference diagram for explaining chemical adsorption of an organic compound containing a sulfur element in an antioxidant according to the present application onto a surface of a metal oxide.

[0034] Figure 3 An exemplary membrane-electrode assembly according to an exemplary embodiment of the present application is shown.

[0035] Figure 4 An exemplary manufacturing method of an exemplary antioxidant for a fuel cell according to an exemplary embodiment of the present application is shown.

[0036] Figure 5A , 5B and 5C are photographs of Example 1, Example 2, and Comparative Example 2, respectively.

[0037] Figure 6 Measurement results of a fluoride release rate (FER) of each electrolyte membrane are shown to evaluate the antioxidant ability of the electrolyte membranes of Examples 1 and 2 and Comparative Examples 1 to 3. DETAILED DESCRIPTION

[0038] The above and other objects, features and advantages of the present application will be more clearly understood from the following preferred embodiments taken in conjunction with the accompanying drawings. However, the present application is not limited to the embodiments disclosed herein and can be modified in various forms. The embodiments are provided to explain the present application thoroughly and to deliver the spirit of the present application to those skilled in the art.

[0039] Throughout the drawings, like reference numerals will be used to designate like or similar elements. For the clarity of the present application, the sizes of structures are exaggerated relative to each other. It should be understood that, although the terms such as "first", "second", and the like can 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, a "first" element discussed below can be termed a "second" element without departing from the scope of the present application. Similarly, a "second" element can also be termed a "first" element. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0040] It should also be understood that, when used in this specification, the terms "comprises", "comprising", "includes", "including", "has", "having" and the like are intended to indicate the presence of stated features, integers, steps, operations, elements, components or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components or combinations thereof. Also, it should be understood that, when an element such as a layer, film, region, or plate is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element such as a layer, film, region, or plate is referred to as being "under" another element, it can be directly under the other element, or intervening elements can also be present. Furthermore, unless otherwise specified, like numbers refer to like elements throughout the specification.

[0041] Unless otherwise indicated, all numbers expressing quantities of components, reaction conditions, polymer compositions, and amounts of materials herein are to be understood as approximations based on the desired property sought to be obtained by those of ordinary skill in the art using the normal techniques for making these measurements, and thus can vary by a small amount from the indicated values. These variations are to be understood to be within the scope of the term "about" as described herein.

[0042] As used herein, the term "about", unless otherwise specified, is understood to be within the normal tolerances of the art, e.g., within 2 standard deviations of the mean. "About" can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context clearly indicates otherwise, none of the numbers provided herein are modified by the term "about".

[0043] Further, when disclosing numerical ranges in this specification, these ranges are continuous and include all values from the lower value and to the upper value, unless otherwise indicated. Furthermore, when such a range includes both integers and fractional values, unless otherwise indicated, the range is intended to include the integer values from the lower value and to the upper value, as well as the fractional values. For example, a range of "5-10" should be interpreted to include any sub-range, e.g., 6-10, 7-10, 6-9, 7-9, etc., as well as the individual values 5, 6, 7, 8, 9, and 10, and should also be interpreted to include any value within the stated range, e.g., 5.5, 6.5, 7.5, 5.5-8.5, 6.5-9, etc. Additionally, a range of, e.g., "10-30%" would be interpreted to include sub-ranges such as 10-15%, 12-18%, 20-30%, etc., as well as all integers within the stated range, e.g., 10, 11, 12, 13, etc., up to 30, and should also be interpreted to include any value within the stated range, e.g., 10.5%, 15.5%, 25.5%, etc.

[0044] In one aspect, an antioxidant capable of improving chemical durability of a fuel cell or an electrode or electrolyte membrane included therein is provided.

[0045] Figure 1 An exemplary antioxidant for a fuel cell according to an exemplary embodiment of the present application is shown. Referring to the figure, the antioxidant 1 includes a metal oxide 10 having an antioxidant ability and an organic compound 20 containing a sulfur element adsorbed on the metal oxide 10.

[0046] The metal oxide 10 can be represented by the following Chemical Formula 1.

[0047] [Chemical Formula 1]

[0048] MO 2-δ

[0049] M can include one or more selected from the group consisting of transition metals and rare earth metals, and δ is an oxygen vacancy value that makes the metal oxide electrically neutral.

[0050] Preferably, M can suitably include one or more selected from the group consisting of zirconium (Zr), cerium (Ce), samarium (Sm), gadolinium (Gd), and terbium (Tb).

[0051] The metal oxide 10 can be supported on a support (not shown).

[0052] The support can include one or more selected from the group consisting of titanium dioxide (TiO2), silicon dioxide (silica, SiO2), cerium oxide, cerium zirconium oxide, gadolinium-doped cerium oxide, titanium oxide-supported cerium oxide, and silicon dioxide-supported cerium oxide. However, the present application is not limited thereto, and any support can be used without limitation as long as it has an antioxidant ability and can be used for a fuel cell.

[0053] The metal oxide 10 can have a crystallite size of about 1 nm to 100 nm, about 5 nm to 80 nm, or preferably about 10 nm to 50 nm. When the crystallite size of the metal oxide 10 is less than about 1 nm, the solubility of the antioxidant can greatly increase, and thus the long-term stability can decrease. On the other hand, when the crystallite size thereof is greater than about 100 nm, the antioxidant ability can decrease. As used herein, the crystallite size can be measured by X-ray diffraction (XRD) technique.

[0054] The average particle size of the agglomerates of the metal oxide 10 can be about 900 nm or less, about 500 nm or less, or preferably about 100 nm or less. When the average particle size of the agglomerates of the metal oxide 10 is greater than about 900 nm, the dispersibility and / or the distribution in the electrolyte membrane can be greatly reduced. The lower limit of the average particle size of the agglomerates of the metal oxide 10 is not particularly limited, and, for example, can be 10 nm or 1 nm.

[0055] The method of manufacturing the antioxidant can include pulverizing the metal oxide 10 and the organic compound 20 containing sulfur such as a sulfmic acid anion group (R-SO2 - ) of the organic compound 20. The average particle size of the pulverized metal oxide 10 is preferably within the above numerical range.

[0056] The organic compound 20 containing sulfur can be adsorbed on the surface of the metal oxide 10, and thereby improve the distribution stability of the metal oxide 10. Also, a compound having an intrinsic antioxidant ability can be used, thereby further improving the antioxidant ability of the antioxidant 1.

[0057] The organic compound 20 can suitably include formamidine sulfmic acid or sulfurous acid dihydrate, as shown in the following Structural Formula 1.

[0058] [Structural Formula 1]

[0059]

[0060] The organic compound 20 is adsorbed on the surface of the metal oxide 10. The sulfmic acid (R-SO2H) of the organic compound 20 represented by Structural Formula 1 can be oxidized to provide a compound having a sulfmic acid anion group (R-SO2 - ) represented by the following Structural Formula 2. The organic compound 20 is adsorbed on the metal oxide 10 through the sulfmic acid anion group.

[0061] [Structural Formula 2]

[0062]

[0063] As used herein, the organic compound containing sulfur such as sulfmic acid (R-SO2H) can be in an electrically neutral state as shown in Structural Formula 1, or in an ionic state as shown in Structural Formula 2. This depends on whether it is adsorbed on the metal oxide 10 or not, and the non-adsorbed state refers to the former and the adsorbed state refers to the latter. The meaning should be fully understood based on the context of the corresponding part.

[0064] Figure 2 A graph showing the chemical adsorption of the sulfur-containing organic compound 20 on the surface of the metal oxide 10 is shown. In the graph, the horizontal axis represents the time, and the vertical axis represents the concentration of the sulfur-containing organic compound 20. Figure 2In this case, the metal oxide 10 can be cerium oxide, for example, tetravalent cerium cations (Ce 4+ ) on the surface of the metal oxide 10 can be reduced to trivalent cerium cations (Ce 3+ ), thereby causing oxygen vacancies.

[0065] By adsorbing the sulfur-containing organic compound 20 on the surface of the metal oxide 10, protective stabilization of the surface of the metal oxide 10 can be induced, thereby ensuring distribution stability of the antioxidant.

[0066] In addition, the sulfur-containing organic compound 20 can include thiourea (H2NCSNH2) as a type of functional group connected to a sulfinate anion group. Thiourea alone can have antioxidant ability to stabilize hydroxyl radicals. Thus, the sulfur-containing organic compound 20 can be adsorbed on the metal oxide 10, thereby further improving the antioxidant ability of the antioxidant.

[0067] The mass ratio of the metal oxide 10 to the sulfur-containing organic compound 20 can be about 10:0.1 to 5, or preferably about 10:0.5 to 4. When the mass ratio of the above two components falls within the above numerical range, both the antioxidant ability and the distribution stability can be improved. When the mass ratio is less than about 10:1, the amount of the sulfur-containing organic compound adsorbed on the surface of the metal oxide is too small, and thus the effect of increasing the antioxidant ability can be insufficient. On the other hand, when the mass ratio is greater than about 10:4, the amount of the sulfur-containing organic compound adsorbed on the surface of the metal oxide is too large, and thus the distribution stability can be decreased due to coalescence of the excess antioxidant.

[0068] Figure 3 An example membrane-electrode assembly 60 according to an example embodiment of the present application is shown. For example, the membrane-electrode assembly 60 can include an electrolyte membrane 30, a positive electrode 40 disposed on one side of the electrolyte membrane 30, and a negative electrode 50 disposed on the other side of the electrolyte membrane 30.

[0069] The positive electrode 40 is configured to react with oxygen in the air, and the negative electrode 50 is configured to react with hydrogen. Preferably, at the negative electrode 50, hydrogen is split into protons and electrons by a hydrogen oxidation reaction (HOR). The protons move through the electrolyte membrane 30 in contact with the negative electrode 50 to the positive electrode 40. The electrons move through an external circuit (not shown) to the positive electrode 40.

[0070] The positive electrode 40 and the negative electrode 50 can include carbon-supported Pt catalysts, and can also include ionomer binders for proton conduction in these electrodes.

[0071] The electrolyte membrane 30 can include an ionomer having proton conductivity. Any ionomer can be used, as long as it is capable of transporting protons. Examples thereof can include perfluorosulfonic acid (PFSA) ionomers.

[0072] At least one of the electrolyte membrane 30, the positive electrode 40, or the negative electrode 50 can include the above-described antioxidant, and preferably the electrolyte membrane 30 includes the antioxidant.

[0073] Figure 4 An example method of an example antioxidant for a fuel cell using the device according to the example embodiment of the present application is shown. The method can include preparing a raw material including a metal oxide and a sulfur-containing organic compound (S10), pulverizing the raw material (S20), and heat-treating the pulverized raw material (S30).

[0074] The metal oxide and the sulfur-containing organic compound are as described above, and thus a detailed description thereof is omitted.

[0075] The raw material can be pulverized by dry milling. For example, the bead milling is performed at about 50 rpm to 1,000 rpm, or about 100 rpm to 500 rpm. When the rate of the bead milling is less than about 50 rpm, the pulverization effect is very low, and thus the effect of uniformly adsorbing the sulfur-containing organic compound on the surface of the metal oxide is too low. On the other hand, when the bead milling rate is greater than about 1,000 rpm, the effect of adsorbing the sulfur-containing organic compound on the surface of the metal oxide can be reduced due to excessive self-heating caused by friction between the antioxidant particles.

[0076] Thereafter, in order to more stably fix the sulfur-containing organic compound on the surface of the metal oxide, the metal oxide antioxidant on which the sulfur-containing organic compound is adsorbed, obtained by the pulverization, can be heat-treated at a temperature of 40°C to 250°C, or about 50°C to 150°C. When the heat treatment temperature is less than about 40°C, the heat treatment effect can be insufficient, making it difficult to stably fix the adsorbed sulfur-containing organic compound on the surface of the metal oxide. On the other hand, when the heat treatment temperature is greater than about 250°C, the adsorbed sulfur-containing organic compound can be thermally degraded, making it difficult to stably fix it on the surface of the metal oxide.

[0077] Moreover, in order to more stably fix the sulfur-containing organic compound on the surface of the metal oxide, the metal oxide antioxidant on which the sulfur-containing organic compound is adsorbed, obtained by the pulverization, can be heat-treated for about 20 minutes to 15 hours, or about 2 hours to 6 hours. When the heat treatment time is less than about 20 minutes, the heat treatment effect can be insufficient, making it difficult to stably fix the adsorbed sulfur-containing organic compound on the surface of the metal oxide. On the other hand, if the heat treatment time is greater than about 15 hours, the adsorbed sulfur-containing organic compound can be thermally degraded, making it difficult to stably fix it on the surface of the metal oxide, and further the productivity can be reduced due to the long processing time.

[0078] The antioxidant thus obtained can be used to manufacture the electrolyte membrane 30. The method thereof is not particularly limited, and the antioxidant can be applied in various forms, such as a solid powder or a suspension. For example, the antioxidant can be added to a dispersion of an ionomer and uniformly dispersed therein, and the resulting solution can be coated on a substrate and dried, thereby manufacturing the electrolyte membrane.

[0079] To maximize the improvement in chemical durability of the electrolyte membrane by adding the antioxidant of the present application thereto, the amount of the antioxidant added to the dried solid electrolyte membrane must be about 0.05 to 4 wt%, or about 0.2 to 1 wt% based on the total weight of the electrolyte membrane. When the amount of the antioxidant is less than about 0.05 wt%, the effect of improving the chemical durability of the electrolyte membrane can be insufficient. On the other hand, when the amount thereof is greater than about 4 wt%, the proton conductivity of the electrolyte membrane can be greatly reduced, and effective adhesion can become difficult when a membrane-electrode assembly is manufactured by assembling an electrode to the electrolyte membrane.

[0080] Examples

[0081] A better understanding of the present application can be obtained through the following examples, which are set forth to illustrate, but are not to be construed as limiting the present application.

[0082] Antioxidant Preparation Example 1

[0083] As the metal oxide, cerium oxide (CAS Registry Number: 1306-38-3) was used. The crystallite size of the cerium oxide was measured to be about 25 nm by X-ray diffraction.

[0084] As the sulfur-containing organic compound, formamidine sulfmic acid (CAS Registry Number: 1758-73-2, Sigma Aldrich) was used.

[0085] The cerium oxide and the formamidine sulfmic acid were mixed and subjected to bead milling at about 300 rpm, whereby the formamidine sulfmic acid was adsorbed on the surface of the cerium oxide. The mass ratio of the cerium oxide to the formamidine sulfmic acid was adjusted to 10: 1.

[0086] The average particle diameter of the antioxidant agglomerate after pulverization was about 80 nm.

[0087] Finally, heat treatment was performed at a temperature of about 80°C for 3 hours, thereby completing the stable adsorption between the cerium oxide and the formamidine sulfmic acid, and finally obtaining the antioxidant.

[0088] Antioxidant Preparation Example 2

[0089] The antioxidant was prepared in the same manner as in Preparation Example 1, except that the mass ratio of the cerium oxide to the formamidine sulfmic acid was adjusted to 10:2.

[0090] Examples 1 and 2

[0091] The antioxidant of Preparation Examples 1 and 2 was added to and dispersed in a perfluorosulfonic acid-based ionomer dispersion (Nafion® D2021, DuPont, USA) respectively, and then the resulting ionomer dispersion was applied to a substrate such as a film and dried, thereby producing electrolyte membranes of Example 1 and 2. Here, the amount of antioxidant added to the dried solid electrolyte membrane was fixed at 0.8 wt%.

[0092] Comparative Example 1 A perfluorinated sulfonic acid-based ionomer dispersion (Nafion® D2021, DuPont, USA) to which no antioxidant was added was applied to a substrate such as a film and dried, thereby producing an electrolyte membrane. The production method and conditions of the electrolyte membrane were the same as those of Example 1 and 2, and the amount of antioxidant added to the dried solid electrolyte membrane was fixed at 0 wt%.

[0093]

[0094] Comparative Example 2 An antioxidant containing cerium oxide alone at a cerium oxide:formamidine sulfonic acid mass ratio of 10:0, i.e., an antioxidant not containing formamidine sulfonic acid as a sulfur-containing organic compound, was added to and dispersed in a perfluorinated sulfonic acid-based ionomer dispersion (Nafion® D2021, DuPont, USA). The production method and conditions of the electrolyte membrane were the same as those of Example 1 and 2, and the amount of antioxidant added to the dried solid electrolyte membrane was fixed at 0.8 wt%.

[0095]

[0096] An antioxidant containing formamidine sulfonic acid alone at a cerium oxide:formamidine sulfonic acid mass ratio of 0:10, i.e., an antioxidant not containing cerium oxide, was added to and dispersed in a perfluorinated sulfonic acid-based ionomer dispersion (Nafion® D2021, DuPont, USA). The production method and conditions of the electrolyte membrane were the same as those of Example 1 and 2, and the amount of antioxidant added to the dried solid electrolyte membrane was fixed at 0.8 wt%. Comparative Example 3 The composition of the antioxidant of each of the examples and comparative examples and the content of the antioxidant in the electrolyte membrane are summarized in Table 1 below.

[0097] Table 1

[0098]

[0099]

[0100]

[0101] ​​​​Test Example 1 - Appearance Evaluation of Antioxidants

[0102] Figure 5A , 5B Photographs 5C and 5C show antioxidants with cerium oxide:mistine sulfinic acid mass ratios of 10:1 (Example 1), 10:2 (Example 2), and 10:0 (Comparative Example 2), respectively. The antioxidant of Comparative Example 2, which did not adsorb mistine sulfinic acid, showed a pale yellow surface. However, as shown in Examples 1 and 2, the surface color of the antioxidant changed from yellow to light brown as the amount of mistine sulfinic acid on the surface increased.

[0103] Test Example 2 - Distribution Stability Evaluation

[0104] The surface charge of the antioxidant of Example 1, comprising cerium oxide and methanesulfinic acid in a mass ratio of 10:1, was measured. The zeta potential of cerium oxide alone was -3 mV, and the zeta potential of the antioxidant of Example 1, in which methanesulfinic acid was adsorbed onto the cerium oxide surface, was -23.7 mV, indicating a significant increase in value. Therefore, the distribution stability of the antioxidant obtained by adsorbing methanesulfinic acid onto cerium oxide is greatly improved.

[0105] Test Example 3 - Antioxidant Capacity Evaluation

[0106] To evaluate the antioxidant capacity of the electrolyte membranes in Comparative Examples 1 to 3 and Examples 1 and 2, Fenton tests were performed on each electrolyte membrane, and their fluoride release rates were measured. The results are as follows: Figure 6 As shown in the image.

[0107] like Figure 6 As shown, compared to Comparative Examples 1 to 3, the electrolyte membranes of Examples 1 and 2 exhibited lower fluoride release rates, thus improving the chemical durability of the electrolyte membranes. Specifically, compared to Comparative Examples 2 and 3, where cerium oxide or methanesulfinic acid was used alone as an antioxidant, in Examples 1 and 2, where cerium oxide and methanesulfinic acid were used together in a manner where methanesulfinic acid was adsorbed onto the surface of cerium oxide, the fluoride release rate of the electrolyte membrane was significantly reduced due to the synergistic antioxidant effect, and the chemical durability of the electrolyte membrane was improved.

[0108] Although various exemplary embodiments of the invention have been described with reference to the accompanying drawings, those skilled in the art should understand that the invention can be implemented in other preferred forms without altering its technical spirit or essential characteristics. Therefore, the above embodiments should be understood in various ways as non-limiting and illustrative.

Claims

1. An antioxidant for use in fuel cells, comprising: Metal oxides; and Contains the sulfinic acid anion group R-SO2 - And the organic compounds adsorbed on the metal oxide, The metal oxide mentioned above is represented by the following chemical formula 1: [Chemical Formula 1] FOR 2-δ Where M includes one or more selected from the group consisting of zirconium, cerium, samarium, gadolinium, and terbium, and δ is the oxygen vacancy value that makes the metal oxide electrically neutral. The organic compound mentioned therein includes formamidinium sulfinic acid.

2. The antioxidant according to claim 1, wherein, The metal oxide is loaded onto a carrier, and The carrier includes one or more of the following: titanium dioxide, silicon dioxide, cerium oxide, cerium zirconium oxide, gadolinium-doped cerium oxide, cerium oxide supported on titanium oxide, and cerium oxide supported on silicon dioxide.

3. The antioxidant according to claim 1, wherein, The metal oxide has a crystallite size of 1 nm to 100 nm.

4. The antioxidant according to claim 1, wherein, The agglomerates of the metal oxide have an average particle size of 1 nm to 900 nm.

5. The antioxidant according to claim 1, wherein, The mass ratio of the metal oxide to the organic compound is from 10:0.1 to 10.

6. A method for manufacturing the antioxidant of claim 1, comprising: Prepare a mixture comprising metal oxides and sulfur-containing organic compounds; Crush the mixture; and The mixture was heat-treated and pulverized.

7. The method according to claim 6, wherein, The mixture is pulverized by dry grinding.

8. The method according to claim 6, wherein, The mixture was pulverized at 50 rpm to 1,000 rpm.

9. The method according to claim 6, wherein, The mixture is heat-treated and pulverized at a temperature of 40°C to 250°C.

10. The method according to claim 6, wherein, The pulverized mixture is heat-treated for 20 minutes to 15 hours.

11. An electrolyte membrane comprising the antioxidant of claim 1.

12. The electrolyte membrane according to claim 11, wherein, The electrolyte membrane contains the antioxidant in an amount of 0.05 wt% to 4 wt% of the total weight of the electrolyte membrane.

13. A membrane-electrode assembly, comprising: Electrolyte membrane; The positive electrode is disposed on one side of the electrolyte membrane; and The negative electrode is located on the other side of the electrolyte membrane. The electrolyte membrane, the positive electrode, or the negative electrode comprises at least one of the antioxidants according to claim 1.

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