Highly dispersible radical scavenger having low leachability and reversible regenerability, and electrolyte membrane including same

Abstract

The present invention relates to a highly dispersible organic-inorganic hybrid nanoparticle radical scavenger having low leachability and reversible regenerability, and a highly durable electrolyte membrane including same. The highly dispersible organic-inorganic hybrid nanoparticle radical scavenger includes nanoparticles in which oxides of cerium (Ce) and silicon (Si) and oxides of at least one metal (M) selected from transition metals and lanthanides are bonded, wherein the nanoparticles have at least one functional group selected from an alkyl group and a fluoroalkyl group.

Description

A highly dispersible radical scavenger having low dissolution and reversible regeneration capabilities and an electrolyte membrane containing the same

[0001] The present invention relates to a highly dispersed organic-inorganic hybrid nanoparticle radical scavenger having low dissolution and reversible regenerative properties, a method for manufacturing the same, an ionomer comprising the radical scavenger, and a highly durable electrolyte membrane. The present invention is characterized by further improving the electrochemical performance of an electrolyte membrane by introducing an organic molecular structure similar in chemical structure to the ionomer of the electrolyte membrane into metal oxide nanoparticles and utilizing them as radical scavengers.

[0002] Electrolyte membranes, which are key materials determining the performance of membrane electrode assemblies (MEAs) in electrochemical cells such as fuel cells and water electrolysis, are manufactured using perfluorinated sulfonic acid ionomers (PFSA). However, there is a problem in that the ionomer undergoes chemical degradation due to radicals generated during cell operation, which leads to a rapid decline in the performance and durability of the electrochemical cell. For example, radicals can be generated when hydrogen peroxide reacts with polyvalent metal ions due to corrosion of metal components constituting the fuel cell system and hydrogen permeated through the reinforced composite membrane to produce reactive oxygen species (ROS). To suppress the generation of such radicals, a method of introducing radical scavengers into the electrolyte membrane is being used.

[0003] There are cases where cerium-based metal salt compounds such as Ce(NO3)3 and Ce(OH)4 are introduced into reinforced composite membranes for hydrogen electric vehicles as ionic radical scavengers, but there are limitations in applying them to large-volume dispersions due to the formation of insoluble salts, and hydrogen ions may be reduced due to the formation of ionic complexes between sulfate groups at the end of the PFSA ionomer side chain and cerium ions, and there are problems with cerium ion migration and elution caused by electrical attraction between electrode voltages generated during fuel cell operation.

[0004] Meanwhile, metal oxide nanoparticles are known to be effective in improving the oxidation and chemical stability of materials by removing various active radicals. Examples of such metal oxide nanoparticles include cerium oxide, zirconium oxide, manganese oxide, aluminum oxide, vanadium oxide, and cerium-zirconium oxide nanoparticles.

[0005] However, when metal oxide nanoparticles are introduced into an ionomer dispersion, there is a limitation in that precipitation or self-aggregation between particles occurs due to high density, which prevents long-term dispersion stability from being secured. In particular, when metal oxide nanoparticles are introduced into PFSA ionomer-based reinforced composite membranes, mechanical properties deteriorate due to low compatibility, which may lead to cracking or fracture and reduce gas barrier properties. Consequently, additional surfactants or dispersants must be added to improve the dispersion stability of metal oxide nanoparticles, which complicates the manufacturing process and increases costs, making it undesirable in terms of manufacturing process efficiency.

[0006] Therefore, there is a need to develop radical scavenger nanoparticles that minimize spontaneous aggregation without using additives such as surfactants or dispersants, and possess uniform dispersibility within the ionomer after electrolyte membrane formation. Furthermore, research is being conducted on the fabrication of high-performance electrolyte membranes and MEAs utilizing radical scavenger nanoparticles that can solve the problem of metal ion leaching during electrochemical cell operation and possess continuous radical decomposition capabilities.

[0007] The problem that the present invention aims to solve is to provide a highly dispersed organic-inorganic hybrid nanoparticle radical scavenger having low dissolution and reversible regeneration capabilities, and a method for manufacturing the same.

[0008] Another objective of the present invention is to improve the performance of electrochemical cells, such as fuel cells, water electrolysis, brine electrolysis, and ammonia electrolysis, by developing an ionomer containing a highly dispersible radical scavenger, a highly durable electrolyte membrane, and a membrane electrode assembly (MEA) produced thereby.

[0009] One aspect of the present invention provides a radical scavenger comprising an organic-inorganic hybrid nanoparticle combined with an oxide of cerium (Ce) and silicon (Si) and an oxide of one or more metals (M) selected from transition metals and lanthanides, wherein the nanoparticle has one or more functional groups selected from alkyl groups and fluoroalkyl groups.

[0010] According to the example, the organic-inorganic hybrid nanoparticle may be represented by the following [Chemical Formula 1].

[0011] [Chemical Formula 1]

[0012] CeOx-MOy-SiOz-R

[0013] (In the above formula, M is one or more metals selected from transition metals and lanthanides, x, y, and z are each independently integers from 1 to 4, R is selected from one or more of -(CH2)m-, -(CF2)n-, and -(CH2)m-(CF2)n-, and m and n are each independently integers from 1 to 20).

[0014] The above R may be one or more selected from, for example, -(CH2)2-(CF2)5-CF3, -(CH2)2-(CF2)7-CF3, and -(CH2)2-(CF2)9-CF3, but is not limited thereto.

[0015] The above M may be one or more of Zr, Ti, Sm, Eu, Nd, Pr, and La, but is not limited thereto.

[0016] The molar ratio of the above cerium (Ce) and metal (M) is preferably in the range of 2:1 to 2:0.25, but is not limited thereto.

[0017] According to the example, the size of the organic-inorganic hybrid nanoparticle may be in the range of 1.0 to 40 nm, preferably in the range of 1 to 20 nm, and more preferably in the range of 1 to 10 nm.

[0018] The radical scavenger according to the example may be capable of being redispersed to a nano size in an organic solvent or ionomer.

[0019] Another aspect of the present invention provides a method for producing a radical scavenger comprising: i) preparing a solution comprising a fluorosilane compound containing an alkyl group or an alkoxy group and an oxide precursor of a metal selected from one or more of transition metals or lanthanides; ii) adding a cerium oxide precursor to the solution to produce organic-inorganic hybrid nanoparticles through a hydro-condensation reaction; and iii) adding a basic solution to the solution to precipitate and separate the nanoparticles.

[0020] In addition, the method for manufacturing an organic-inorganic hybrid radical scavenger according to the embodiment may further include the step of drying the nanoparticles separated in step iii) to produce nanoparticles in a fine powder state.

[0021] In the above method for manufacturing a radical scavenger, the transition metal or lanthanide may be one or more of Zr, Ti, Sm, Eu, Nd, Pr, and La, but is not limited thereto.

[0022] The mixing ratio of the oxide precursor of a metal selected from one or more of the above transition metals and lanthanides to the cerium oxide precursor is preferably in the range of 2:1 to 2:0.25 in molar ratio, but is not limited thereto.

[0023] The above basic solution may be one or more selected from, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and aqueous ammonia solution, but is not limited thereto.

[0024] Another aspect of the present invention provides an ionomer or an ionomer dispersion comprising a radical scavenger comprising the organic-inorganic hybrid nanoparticles.

[0025] The above ionomer may be one or more selected from perfluorinated sulfonic acid ionomers or hydrocarbon sulfonic acid ionomers, but is not limited thereto.

[0026] Among the above ionomers, the radical scavenger may be included in a range of 0.001 to 20 weight% based on the ionomer solid content, but is not limited thereto.

[0027] Another aspect of the present invention provides an electrolyte membrane comprising the radical scavenger. The electrolyte membrane may be prepared using an ionomer dispersion comprising the organic-inorganic hybrid nanoparticles.

[0028] According to the embodiments, the electrolyte membrane may be a freestanding membrane (pure membrane) or a reinforced composite membrane, but is not limited thereto.

[0029] The above electrolyte membrane may be applied, for example, to hydrogen electric vehicle fuel cells, power generation fuel cells, PEM water electrolysis, ALK water electrolysis, AEM water electrolysis, and ammonia electrolysis cells, but is not limited thereto. The electrolyte membrane containing the above organic-inorganic hybrid radical scavenger may be included in a membrane electrode assembly (MEA) and applied to an electrochemical cell.

[0030] The organic-inorganic hybrid radical scavenger nanoparticles according to the present invention are evenly dispersed in an ionomer without aggregation, even without a separate surfactant or dispersant, and can maintain a dispersed state for a long period of time, such as several months or more.

[0031] The organic-inorganic hybrid radical scavenger nanoparticles prepared according to the present invention have excellent dispersibility, to the extent that they can be redispersed in nanoparticle size in an aqueous alcohol solution in which an ionomer is dispersed. Therefore, since non-aggregation dispersion is possible even when a porous support containing pores of tens to hundreds of nanometers in size is introduced to supplement mechanical strength, they can be effectively applied to the manufacturing process of reinforced composite membranes having a defect-free structure.

[0032] In particular, when an organic-inorganic hybrid radical scavenger prepared according to the present invention is applied to an electrolyte membrane, metal ions having a radical scavenger function under acidic conditions (e.g., cerium ions, Ce 3 + By reducing the leaching of ), it is possible to secure continuous radical decomposition ability when operating an electrochemical cell, thereby improving long-term operating characteristics.

[0033] Figure 1 is a schematic diagram showing the chemical structure of organic-inorganic hybrid nanoparticles prepared according to an embodiment of the present invention.

[0034] Figure 2 is a graph showing the results of the oxidation stability evaluation of electrolyte membrane samples prepared according to comparative examples and examples.

[0035] Figure 3 is a graph showing the OCV durability test results of an MEA with an electrolyte membrane prepared according to a comparative example and an example.

[0036] The present invention will be described in more detail below with reference to the examples and drawings. However, the following examples are provided as examples to aid in understanding the invention and the scope of the invention is not limited thereto. The present invention may be subject to various modifications and may be implemented in various different forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the invention.

[0037] The organic-inorganic hybrid type radical scavenger nanoparticles according to the example are designed to minimize spontaneous aggregation of nanoparticles when introduced into an aqueous alcohol solution in which an ionomer is dispersed, without using additives such as surfactants or dispersants, and by including an organic molecular structure containing -CF2 / -CH2 groups (e.g., R=-(CH2)2-(CF2)5-CF3) that has chemical structural similarity to the fluorine-based / hydrocarbon-based ionomer used for manufacturing electrolyte membranes. This ensures uniform dispersion within the ionomer after forming the electrolyte membrane.

[0038] In addition, the organic-inorganic hybrid type nanoparticles according to the embodiment have a radical scavenger function under acidic conditions, with metal ions (e.g., cerium ions, Ce) 3 + The phenomenon of easy leaching from the ionomer in the electrolyte membrane (Cerium migration) introduced by ) is shielded through the organic molecular structure (R) connected by covalent bonds, thereby reducing metal ion leaching during the operation of the electrochemical cell and improving the chemical durability of the electrolyte membrane.

[0039] In addition, the organic-inorganic hybrid type radical scavenger nanoparticles according to the example exhibit oxidation-reduction cycling characteristics between multivalent ions (M 3+ ↔ M 4+ A transition metal or lanthanide (M) having ) can be incorporated into hybrid nanoparticles and applied to an electrolyte membrane, and continuous radical decomposition capability can be secured when operating an electrochemical cell containing the electrolyte membrane.

[0040] The radical scavenger according to the embodiment is a radical scavenger comprising an organic-inorganic hybrid nanoparticle combined with an oxide of cerium (Ce) and silicon (Si) and an oxide of one or more metals (M) selected from transition metals and lanthanides, wherein the nanoparticle is characterized by having one or more functional groups selected from alkyl groups and fluoroalkyl groups.

[0041] FIG. 1 is a schematic diagram showing the chemical structure of organic-inorganic hybrid nanoparticles prepared according to an embodiment of the present invention. In FIG. 1, the metal (M) may be a transition metal and a lanthanide metal, and may be one or more selected from, for example, Zr, Ti, Sm, Eu, Nd, Pr, and La, and R is a functional group selected from one or more alkyl groups and fluoroalkyl groups.

[0042] The above organic-inorganic hybrid nanoparticles may include nanoparticles represented by the following [Chemical Formula 1].

[0043] [Chemical Formula 1]

[0044] CeOx-MOy-SiOz-R

[0045] (In the above formula, M is one or more metals selected from transition metals and lanthanides, x, y, and z are each independently integers from 1 to 4, R is selected from -(CH2)m-, -(CF2)n-, and -(CH2)m-(CF2)n-, and m and n are each independently integers from 1 to 20)

[0046] The above R may be one or more selected from, for example, -(CH2)2-(CF2)5-CF3, -(CH2)2-(CF2)7-CF3, and -(CH2)2-(CF2)9-CF3, but is not limited thereto.

[0047] The above M is a transition metal and a lanthanide, and may be selected from one or more of, for example, Zr, Ti, Sm, Eu, Nd, Pr, and La, but is not limited thereto.

[0048] The molar ratio of the above cerium (Ce) and metal (M) is preferably in the range of 2:1 to 2:0.25, but is not limited thereto.

[0049] A method for manufacturing a radical scavenger according to an example may include: i) a step of preparing a solution comprising a fluorosilane compound containing an alkyl group or an alkoxy group and an oxide precursor of a metal selected from one or more of transition metals or lanthanides; ii) a step of preparing organic-inorganic hybrid nanoparticles through a hydro-condensation reaction by adding a cerium oxide precursor to the solution; and iii) a step of precipitating and separating nanoparticles by adding a basic solution to the solution, and may further include a step of preparing nanoparticles in a fine powder state by drying the nanoparticles separated in step iii).

[0050] In the above method for manufacturing nanoparticles, it may be suitable to mix the oxide precursor of a metal selected from one or more transition metals and lanthanides with the cerium oxide precursor in a molar ratio ranging from 2:1 to 2:0.25. This is because if the molar ratio of the transition metal or lanthanide (M) is below the above range, a problem may arise in which the regenerability as a radical scavenger is reduced, and if M exceeds the above range, the content of cerium ions is insufficient, which may result in a decrease in performance as a radical scavenger.

[0051] Examples of fluorosilane compounds containing an alkyl or alkoxy group include 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, trichloro(1H,1H,2H,2H-perfluorooctyl)silane, trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane, triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane, trimethoxy(3,3,3-trifluoropropyl)silane, dimethoxy-methyl(3,3,3-trifluoropropyl)silane, trimethylpentafluoroethylsilane, (heptafluoropropyl)trimethylsilane, and trimethyl(trifluoromethyl)silane. One or more selected from 1H,1H,2H,2H-perfluorododecyltrichlorosilanes may be included, but are not limited thereto.

[0052] Examples of cerium precursors include one or more selected from cerium nitrate, cerium chloride, cerium ammonium nitrate, cerium sulfate, cerium acetate hydrate, cerium acetylacetonate hydrate, cerium bromide, cerium carbonate hydrate, cerium chloride heptahydrate, cerium 2-ethylhexanoate, cerium fluoride, cerium hydroxide, cerium iodide, cerium nitrate hexahydrate, cerium oxalate hydrate, and cerium sulfate hydrate, but are not limited thereto.

[0053] Examples of oxide precursors of one or more metals selected from transition metals or lanthanides include zirconium nitrate, zirconium acetate, zirconium chloride, zirconium propoxide, zirconium butoxide, zirconium hydroxide, titanium isopropoxide, titanium butoxide, titanium ethoxide, titanium methoxide, titanium chloride, titanium oxalate, titanium acetylacetonate, titanium sulfate, samarium nitrate, samarium nitrate hexahydrate, samarium acetate, samarium chloride, samarium propoxide, samarium butoxide, samarium hydroxide, europium nitrate, europium chloride, europium hydroxide, neodymium nitrate, neodymium chloride, neodymium hydroxide, praseodymium nitrate, praseodymium chloride, praseodymium oxalate, lanthanum nitrate, and lanthanum. One or more selected from chloride and lanthanum oxalate may be included, but are not limited thereto.

[0054] The basic solution added for nanoparticle precipitation in the above method for manufacturing the radical scavenger may be one or more selected from, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and aqueous ammonia solution, but any basic aqueous solution capable of pH adjustment will suffice and is not particularly limited thereto.

[0055] When an excess amount of sodium hydroxide or ammonia solution is added to a dispersion of organic-inorganic hybrid nanoparticles, the dispersion stability of the nanoparticles decreases rapidly due to a rapid change in the pH of the solution, and precipitates are formed.

[0056] Meanwhile, the method may further include a step of drying the organic-inorganic hybrid nanoparticles separated by the above precipitate to produce nanoparticles in a powder state, and if necessary, a purification process may be performed before drying. A purification process can be repeated until the aqueous solution becomes neutral, in which the nanoparticle precipitate is centrifuged, filtered, dispersed in water by adding distilled water, centrifuged again, filtered, and dispersed in distilled water. When the neutralized precipitate is dried at room temperature, organic-inorganic hybrid nanoparticles formed by the combination of oxides of cerium (Ce) and silicon (Si) and oxides of one or more metals (M) selected from transition metals and lanthanides can be obtained in a fine powder state having an average size in the range of 1.0 to 20 μm. The nanoparticles in the powder state have high utility because they are easy to redisperse into nanoparticle sizes in organic solvents or ionomers.

[0057] The above organic-inorganic hybrid nanoparticles may be capable of being redispersed to a nano size in an organic solvent or ionomer. The size of the above organic-inorganic hybrid nanoparticles may be in the range of 1.0 to 40 nm, preferably in the range of 1 to 20 nm, and more preferably in the range of 1 to 10 nm. Examples of organic solvents in which the nanoparticles can be dispersed include alcohols, dimethyl sulfoxide, methylpyrrolidone, dimethyl acetamide, etc., but are not particularly limited.

[0058] As such, the present invention is characterized in that fine powder in the range of 1.0 to 20 μm, obtained after separation and drying in the process of manufacturing a radical scavenger, can be redispersed into nano-sized organic-inorganic hybrid nanoparticles in the range of 1 to 40 nm by dispersing it in an organic solvent or ionomer.

[0059] Therefore, when an electrolyte membrane (ion exchange membrane) is prepared using an ionomer or an ionomer dispersion containing organic-inorganic hybrid nanoparticles prepared according to the present invention, the nanoparticles can be evenly dispersed within the ionomer without aggregation even without a separate surfactant or dispersant, and there is an advantage of maintaining the dispersed state for a long time.

[0060] The ionomers that can be used to manufacture the above electrolyte membrane may be one or more selected from perfluorinated sulfonic acid ionomers, partially fluorinated sulfonic acid ionomers, or hydrocarbon sulfonic acid ionomers, but are not limited thereto.

[0061] Specifically, types of perfluorinated sulfonic acid ionomers include poly(perfluorosulfonic acid), copolymers of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid groups, and mixtures thereof. Commercially available products include commercial Nafion, Flemion, Asiplex, 3M ionomer, Dow ionomer, Solvay ionomer, Sumitomo ionomer, and mixtures thereof, but are not particularly limited thereto.

[0062] In addition, examples of partially fluorinated sulfonic acid ionomers include sulfonated poly(arylene ethersulfone-co-vinylidene fluoride), sulfonated trifluorostyrene-graft-poly(tetrafluoroethylene) (PTFE-g-TFS), styrene-graft-sulfonated polyvinylidene fluoride (PVDF-g-PSSA), copolymers containing dicarboxybiphenyl as a monomer, and mixtures thereof, but are not particularly limited thereto.

[0063] Meanwhile, examples of hydrocarbon-based ionomers include, but are not limited to, homopolymers, alternating copolymers, irregular copolymers, block copolymers, multiblock copolymers, graft copolymers, and mixtures thereof comprising one or more hydrocarbons selected from sulfonated imide, sulfonated aryl ethersulfone, sulfonated ether ether ketone, sulfonated benzimidazole, sulfonated arylene ether ketone, sulfonated ether ketone, sulfonated styrene, sulfonated imidazole, sulfonated ether ketone ketone, aryl ether benzimidazole, and combinations thereof.

[0064] One or more solvents selected from alcohol, water, dimethyl sulfoxide, methylpyrrolidone, and dimethyl acetamide may be used as solvents for organic solvents or ionomer dispersions capable of redispersing the above organic-inorganic hybrid nanoparticles. Examples of the above types of alcohols include methanol, ethanol, 1-propanol, isopropyl alcohol, butanol, isobutanol, 2-butanol, tert-butanol, n-pentanol, isopentyl alcohol, 2-methyl-1-butanol, neopentyl alcohol, diethyl carbinol, methyl propyl carbinol, methyl isopropyl carbinol, dimethyl ethyl carbinol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 4-methyl-1-pentanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, 2,2-dimethyl-1-butanol, One or more of 2,3-dimethyl-1-butanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, and 4-heptanol and mixtures thereof may be selected, but are not limited thereto.

[0065] According to the example, when an electrolyte membrane is prepared using an ionomer or an ionomer dispersion, the organic-inorganic hybrid nanoparticle radical scavenger may be included in a range of 0.001 to 20 weight% based on the ionomer solid content, but is not limited thereto.

[0066] It is undesirable for the above nanoparticles to be added to the ionomer in an amount exceeding 20 weight percent, as this is highly likely to cause a degradation in mechanical properties. If an excess amount of nanoparticles is added to an ionomer having flexible properties, it may become brittle and easily break or lose flexibility, making it impossible to manufacture into a separation membrane, and there is a high possibility that the ion exchange capacity will be reduced.

[0067] In addition, the electrolyte membrane manufactured using the above ionomer may be a freestanding membrane (pure membrane) or a reinforced composite membrane including a support, and there are no particular limitations.

[0068] Examples of supports constituting reinforced composite membranes include polyterefluoroethylene, polyvinyl difluoroethylene, polyethylene, polypropylene, polyethylene terephthalate, polyimide, and polyamide. Reinforced composite membranes in which an ionomer is impregnated into such porous supports are widely used because they exhibit high process efficiency, low hydrogen permeability, and improved mechanical strength and hydrogen ion conductivity.

[0069] The electrolyte membrane containing a radical scavenger according to the embodiment has improved durability and may be applied, for example, to hydrogen electric vehicle fuel cells, power generation fuel cells, PEM water electrolysis, ALK water electrolysis, AEM water electrolysis, and ammonia electrolysis cells, but is not limited thereto.

[0070] The electrolyte membrane containing the above radical scavenger can be incorporated into a membrane electrode assembly (MEA) and applied to an electrochemical cell, thus offering high potential for utilization.

[0071] The present invention is described illustratively below with reference to the embodiments and drawings, but the scope of the invention should not be interpreted as being limited thereto.

[0072] Example 1 (Z-NRS1-containing fluorine-based ionomer)

[0073] A. Preparation of Organic-Inorganic Hybrid Nanoparticles (NRS)

[0074] 0.95 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.05 g of zirconium(IV) propoxide were added to 15 g of propyl alcohol (NPA, n-propyl alcohol) and stirred until a homogeneous phase was formed. The homogeneous solution was reacted in a 60°C oil bath with stirring for 12 hours, after which 0.5 g of Ce(NO₃)₃·6H₂O was added to the solution and stirred until a homogeneous phase was formed, and the reaction was carried out in a 60°C oil bath with stirring for 12 hours.

[0075] 21 g of 1.25 M NaOH was rapidly added to the above reaction solution and stirred for 4 hours to precipitate. The precipitated solution was divided into two 45 mL conical tubes, each weighing 12.5 g, and washed with DI-water up to 45 mL. The conical tubes were placed in a centrifuge and centrifuged at 4000 rpm for 5 minutes. After centrifugation, the DI-water was removed from the conical tubes, and DI-water was added again. The phase-separated particles were mixed using a spatula, and the above process was repeated until a pH of 7 was achieved. The separated particles were dried at room temperature for 15 to 17 hours to obtain organic-inorganic hybrid nanoparticle (Z-NRS1) powder as a radical scavenger.

[0076] B. Preparation of Ionomer Dispersion

[0077] 0.06 g of Z-NRS1 powder prepared in the above example was added to 10 g of a dispersion (solid content 20 wt.%, Chemours, USA) in which a perfluorinated sulfonic acid ionomer was dispersed in a mixed solvent of alcohol and water, and then the process of mixing using a stirrer and sonicating using sonication was repeated for 6 hours to disperse the mixture.

[0078] C. Preparation of Electrolyte Membrane

[0079] The residual bubbles in the above perfluorinated sulfonic acid ionomer dispersion were removed by sonication and ultrasonically treated, and the mixture was cast onto a hydrophilized glass plate at room temperature, dried in a convection oven set to 50 degrees for 3 hours to solidify, and then subjected to a heat treatment process at 210 degrees for 50 minutes to prepare an electrolyte membrane.

[0080] D. Preparation of Membrane Electrode Assembly (MEA)

[0081] A 60 wt.% Pt / C catalyst (VINATech, Korea) was mixed with ultrapure water and isopropyl alcohol (IPA, Sigma-Aldrich, USA) using an ultrasonic cleaner (JAC-3010, Godogiyeon, Korea). Then, a 5 wt.% dispersion of perfluorosulfonic acid ionomer electrode binder (solid content 5 wt.%, Chemours, USA) was added to the catalyst slurry and mixed for an additional 30 minutes. An electrolyte membrane containing the organic-inorganic hybrid nanoparticles prepared above was prepared with a size of 7 cm x 7 cm, having an active area of ​​25 cm². 2 A membrane-electrode assembly (MEA) was prepared by applying a catalyst slurry to both sides of the corresponding area using a spray method. The amount of Pt applied was 0.4 mg / cm² per electrode. 2 It was manufactured to be this way.

[0082] Example 2 (Z-NRS2-containing fluorine-based ionomer)

[0083] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.90 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.10 g of zirconium(IV) propoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS2).

[0084] Example 3 (Z-NRS3-containing fluorine-based ionomer)

[0085] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.85 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.15 g of zirconium(IV) propoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS3).

[0086] Example 4 (Z-NRS4-containing fluorine-based ionomer)

[0087] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and 0.05 g of zirconium(IV) propoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS4).

[0088] Example 5 (Z-NRS5-containing fluorinated ionomer)

[0089] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 1H,1H,2H,2H-perfluorododecyltrichlorosilane and 0.05 g of zirconium(IV) propoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS5).

[0090] Example 6 (Z-NRS6 containing fluorine-based ionomer)

[0091] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 1H,1H,2H,2H-perfluorooctyltrichlorosilane and 0.05 g of zirconium(IV) propoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS6).

[0092] Example 7 (T-NRS1-containing fluorine-based ionomer)

[0093] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that organic-inorganic hybrid radical scavenger nanoparticles (A-NRS1) were prepared using 0.95 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.05 g of titanium isopropoxide.

[0094] Example 8 (T-NRS2-containing fluorine-based ionomer)

[0095] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.10 g of titanium isopropoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (T-NRS2).

[0096] Example 9 (T-NRS3-containing fluorinated ionomer)

[0097] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that organic-inorganic hybrid radical scavenger nanoparticles (T-NRS3) were prepared using 0.95 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.15 g of titanium isopropoxide.

[0098] Example 10 (S-NRS1-containing fluorine-based ionomer)

[0099] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that organic-inorganic hybrid radical scavenger nanoparticles (S-NRS1) were prepared using 0.95 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.05 g of samarium nitrate hexahydrate.

[0100] Example 11 (S-NRS2-containing fluorine-based ionomer)

[0101] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that organic-inorganic hybrid radical scavenger nanoparticles (S-NRS2) were prepared using 0.90 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.10 g of samarium nitrate hexahydrate.

[0102] Example 12 (S-NRS3-containing fluorinated ionomer)

[0103] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that organic-inorganic hybrid radical scavenger nanoparticles (S-NRS3) were prepared using 0.85 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 0.15 g of samarium nitrate hexahydrate.

[0104] Example 13 (Z-NRS7 containing hydrocarbon ionomer)

[0105] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of trimethoxy(3,3,3-trifluoropropyl)silane and 0.05 g of zirconium(IV) propoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS7) and a hydrocarbon sulfonic acid ionomer (sulfonated poly(arylene ether sulfone) random copolymers, degree of sulfonation 32%) was used as the ionomer.

[0106] Example 14 (T-NRS4-containing hydrocarbon ionomer)

[0107] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 13, except that 0.95 g of trimethoxy(3,3,3-trifluoropropyl)silane and 0.05 g of titanium isopropoxide were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (T-NRS4).

[0108] Example 15 (S-NRS4-containing hydrocarbon ionomer)

[0109] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 13, except that 0.95 g of trimethoxy(3,3,3-trifluoropropyl)silane and 0.05 g of samarium nitrate hexahydrate were used to prepare organic-inorganic hybrid radical scavenger nanoparticles (S-NRS4).

[0110] Comparative Example 1 (RS-free fluorine-based ionomer)

[0111] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that a radical scavenger was not added to the perfluorinated sulfonic acid ionomer.

[0112] Comparative Example 2 (M-free RS-containing fluorine-based ionomer)

[0113] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 1, except that organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS1') excluding transition metal / lanthanide metal (M) oxides were added to a perfluorinated sulfonic acid ionomer.

[0114] Comparative Example 3 (ROS-free hydrocarbon ionomer)

[0115] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 13, except that no radical scavenger was added to the hydrocarbon-based sulfonic acid ionomer.

[0116] Comparative Example 4 (M-free RS-containing hydrocarbon ionomer)

[0117] An ionomer dispersion, an electrolyte membrane, and an MEA were prepared in the same manner as in Example 13, except that organic-inorganic hybrid radical scavenger nanoparticles (Z-NRS1') excluding transition metal / lanthanide metal (M) oxides were added to a hydrocarbon-based sulfonic acid ionomer.

[0118] Test Example 1 (Average dispersion particle size)

[0119] A. Test Method

[0120] To analyze the dispersibility of an ionomer dispersion containing radical scavenger nanoparticles, the average dispersed particle size within the dispersion was analyzed by measuring the intensity of scattered light generated when a laser was irradiated onto the dispersion under room temperature conditions, based on the Dynamic Light Scattering (DLS) method.

[0121] B. Test Results

[0122] The results of measuring the average dispersion particle size of the ionomer dispersions prepared in the examples and comparative examples are shown in [Table 1]. The average particle size of the nanoparticles in the ionomer dispersion according to the example was found to be smaller compared to Comparative Example 1 and Comparative Example 2.

[0123] Specifically, it can be seen that the size of the nanoparticles according to the example was in the range of 2.78 nm to 3.45 nm for the fluorine-based ionomer and in the range of 6.72 nm to 6.80 nm for the hydrocarbon-based ionomer.

[0124] From these results, it was confirmed that, according to the examples, introducing an organic chain having chemical structural similarity to the ionomer into radical scavenger nanoparticles, depending on the type of ionomer applied (fluorine-based or hydrocarbon-based), maximizes compatibility with the ionomer and improves dispersibility.

[0125] Ionomer Dispersion Average Dispersed Particle Size [nm] Comparative Example 13.80 Comparative Example 23.70 Example 13.21 Example 23.12 Example 33.20 Example 43.45 Example 53.33 Example 63.40 Example 73.01 Example 82.95 Example 92.78 Example 103.20 Example 112.91 Example 122.82 Comparative Example 37.00 Comparative Example 46.80 Example 136.75 Example 146.66 Example 156.72

[0126] Test Example 2 (Hydrogen ion conductivity of electrolyte membrane)

[0127] A. Test Method

[0128] After measuring the impedance (bulk resistance) at the point where the value of Z" on the Cole-Cole plot converges to 0 in the frequency range of 1 Hz to 20 kHz using the AC four-point probe method under water conditions with an electrolyte membrane sample size of 1 cm x 5 cm and a measurement temperature of 65℃ (fuel cell operating temperature), the result was converted into hydrogen ion conductivity using the following equation.

[0129] Hydrogen ion conductivity [S / cm], σ = L / (R x S)

[0130] [L: Distance between electrodes (cm), R: Film resistance (Ω), S: Film area (cm²) 2 )]

[0131] B. Test Results

[0132] The hydrogen ion conductivity of the electrolyte membranes according to the examples and comparative examples was measured and is shown in [Table 2]. The electrolyte membrane samples according to the examples showed excellent hydrogen ion conductivity when compared to the samples of Comparative Example 1 and Comparative Example 2.

[0133] This indicates that if an organic molecular structure with chemical structural similarity to the applied ionomer (fluorine-based or hydrocarbon-based) is introduced into radical scavenger nanoparticles, compatibility with the ionomer is maximized, preventing degradation of the electrolyte membrane's properties.

[0134] Electrolyte membrane hydrogen ion conductivity [S / cm@65 o C] Comparative Example 10.145 Comparative Example 20.148 Example 10.149 Example 20.148 Example 30.155 Example 40.151 Example 50.149 Example 60.150 Example 70.153 Example 80.155 Example 90.148 Example 100.153 Example 110.152 Example 120.149 Comparative Example 30.162 Comparative Example 40.165 Example 130.168 Example 140.172 Example 150.170

[0135] Test Example 3 (Hydrogen gas permeability of electrolyte membrane)

[0136] A. Test Method

[0137] A square electrolyte membrane sample measuring 2 cm × 2 cm (active area 1 cm × 1 cm) was subjected to a time-lag method in which a gas pressure of 1 atm was injected to measure the change in gas pressure permeating / diffusing through the membrane per hour. The hydrogen gas permeability of the electrolyte membrane was measured based on the time-lag method at △P = 1 atm and a measurement temperature of 65℃ (fuel cell operating temperature).

[0138] B. Test Results

[0139] The hydrogen gas permeability of the electrolyte membranes according to the examples and comparative examples was measured and is shown in [Table 3]. When compared to the samples of Comparative Example 1 and Comparative Example 2, the electrolyte membrane samples according to the examples showed almost no change in hydrogen gas permeability. This indicates that if an organic chain having chemical structural similarity to the ionomer is introduced into the radical scavenger nanoparticles according to the type of ionomer applied (fluorine-based or hydrocarbon-based), compatibility with the ionomer is maximized, and no degradation of the physical properties of the electrolyte membrane occurs.

[0140] Electrolyte Membrane Hydrogen Gas Permeability [Barrer @ 65℃] Comparative Example 1 21.1 Comparative Example 2 20.5 Example 1 19.9 Example 2 20.4 Example 3 20.1 Example 4 19.8 Example 5 19.7 Example 6 20.3 Example 7 19.5 Example 8 20.0 Example 9 20.5 Example 10 19.7 Example 11 19.9 Example 12 20.5 Comparative Example 36.5 Comparative Example 46.3 Example 136.2 Example 146.1 Example 156.1

[0141] Test Example 4 (Oxidation Stability of Electrolyte Membrane)

[0142] A. Oxidative stability of electrolyte membranes

[0143] A Fenton reagent was prepared by reacting 0.1 wt.% ferrous ammonium sulfate with 30 wt.% hydrogen peroxide, and a square electrolyte membrane sample measuring 2 cm × 2 cm was immersed in the Fenton reagent at a temperature of 80°C for 2 hours to test the oxidation stability of the electrolyte membrane as follows.

[0144] When applying a fluorine-based ionomer, the concentration of fluoride ions released from the sample after the Fenton test was analyzed using a pH / ion-selective electrode meter (Orion Star A214, ThermoFisher Scientific, USA) equipped with an ion-selective electrode (model 9609BNWP).

[0145] The oxidation stability of the electrolyte membrane was evaluated by calculating the weight loss rate through weight measurements before and after the Fenton test when a hydrocarbon-based ionomer was applied.

[0146] B, test results

[0147] Figure 2 shows the results of evaluating the oxidation stability of electrolyte membranes treated with fluorine-based ionomers according to Examples 1 to 12 (E1 to E12) and Comparative Examples (C1 to C2). Compared to the electrolyte membrane of Comparative Example 1 (C1), the concentration of fluoride ions released from the electrolyte membranes of Comparative Example 2 (C2), in which radical scavengers were introduced, and the Examples (E1 to E13) was found to be lower. Furthermore, the electrolyte membrane according to the Examples showed a significantly lower fluoride ion concentration when compared to the electrolyte membranes of Comparative Examples 1 and 2. This indicates that when transition metal / lanthanide-based metal oxides are introduced in the preparation of organic-inorganic hybrid nanoparticles according to the Examples, regeneration (Ce 3 + / Ce 4 + It shows that redox cycling is maximized.

[0148] Meanwhile, to evaluate the oxidation stability of the electrolyte membranes to which hydrocarbon-based ionomers were applied according to Examples 13 to 15 and Comparative Examples 3 to 4, the weight loss rate was measured and is shown in [Table 4].

[0149] According to these results, the electrolyte membrane of Comparative Example 3, which did not contain radical scavengers, showed the highest weight loss rate and was confirmed to be partially lost when the Fenton test was completed. Compared to Comparative Example 3, the electrolyte membrane of Comparative Example 4, which introduced radical scavengers, showed a lower weight loss rate after the Fenton test than Comparative Example 3.

[0150] In addition, the electrolyte membrane containing organic-inorganic hybrid radical scavenger nanoparticles according to the example showed a significantly lower weight loss rate compared to the electrolyte membranes of Comparative Examples 3 and 4.

[0151] This is because, according to the example, when a transition metal / lanthanide-based metal oxide is introduced into the preparation of organic-inorganic hybrid nanoparticles, regeneration (Ce 3 + / Ce 4 + It shows that the oxidation stability of the electrolyte membrane is improved as redox cycling is maximized.

[0152] Electrolyte membrane weight loss rate [%] Comparative Example 3 38.2 Comparative Example 4 25.5 Example 13 18.2 Example 14 19.1 Example 15 19.8

[0153] Test Example 5 (IV performance of MEA)

[0154] A. Measurement of MEA IV Performance

[0155] Active area 25 cm 2 The IV performance of a membrane electrode assembly (MEA) with an electrolyte membrane sample applied was measured under conditions of an operating temperature of 65℃, RH = 100 / 100 %, and P = 1.0 bar.

[0156] B. Test Results

[0157] The results of measuring the IV performance of the MEAs with the electrolyte membranes of the Examples and Comparative Examples are shown in [Table 5]. The MEA samples in which organic-inorganic hybrid radical scavenger nanoparticles according to the Examples were introduced showed improved IV performance when compared to the samples of Comparative Examples 1 and 2. This indicates that when organic chains having chemical structural similarity to fluorine-based ionomers are introduced into radical scavenger nanoparticles, compatibility with the ionomer is maximized, and no degradation of the physical properties of the electrolyte membrane occurs.

[0158] Electrolyte membrane current density [A / cm² 2 @0.6 V] Comparative Example 11.100 Comparative Example 21.110 Example 11.200 Example 21.134 Example 31.196 Example 41.167 Example 51.142 Example 61.155 Example 71.187 Example 81.200 Example 91.135 Example 101.184 Example 111.172 Example 121.140

[0159] Test Example 6 (OCV durability test and Ce leaching stability of MEA)

[0160] A. Test Method

[0161] A-1. OCV Durability Test of MEA

[0162] Chemical durability was evaluated by conducting an OCV hold test under conditions of an operating temperature of 90℃, RH = 30 / 30%, and P = 1.5 bar, and measuring the endurance time when the reduction rate of OCV after endurance compared to the initial state of the MEA with the electrolyte membrane sample exceeded 20%.

[0163] A-2. Ce dissolution stability

[0164] Ce content was measured using X-ray fluorescence spectrometry (XRF) before and after the OCV endurance test, and the change in Ce content after OCV endurance was observed relative to the initial amount of Ce introduced into the radical scavenger. The Ce dissolution stability within the radical scavenger was evaluated through an analysis of Ce loss.

[0165] B. Test Results

[0166] The results of the OCV durability test of MEAs with electrolyte membranes applied according to the Examples and Comparative Examples are shown in Fig. 3 and Table 5. As a result of the OCV durability test of MEAs with electrolyte membrane samples, Comparative Example 1 showed a rapid decrease in OCV over time, and the durability evaluation ended at 112 hours, while Comparative Example 2 (C2) ended the durability evaluation at 190 hours, approximately 80 hours later than Comparative Example 1 (C1). Meanwhile, the electrolyte membrane of Example 1 (E1) exhibited the longest durability time at 302 hours. This suggests that introducing organic chains with chemical structural similarity to fluorine-based ionomers into radical scavenger nanoparticles improves compatibility with the ionomer, and introducing transition metal / lanthanide-based metal oxides in the preparation of organic-inorganic hybrid nanoparticles allows for the Ce on the nanoparticle surface through metal ion bonding. 3 + Minimization of content loss and long-term reversible regenerative functionality (Ce 3 + / Ce 4 + redox cycling is seen as a maximized effect.

[0167] MEAOCV End-of-life [h] Ce leaching stability (Ce loss rate) [%] Comparative Example 11 12 - Comparative Example 21 90 15.5 Example 13 0 21 1.3

Claims

1. A radical scavenger comprising organic-inorganic hybrid nanoparticles combined with oxides of cerium (Ce) and silicon (Si) and oxides of one or more metals (M) selected from transition metals and lanthanides, wherein the nanoparticles have one or more functional groups selected from alkyl groups and fluoroalkyl groups.

2. In Paragraph 1, Radical scavenger comprising organic-inorganic hybrid nanoparticles represented by the following [Chemical Formula 1]: [Chemical Formula 1] CeOx-MOy-SiOz-R (In the above formula, M is one or more metals selected from transition metals and lanthanides, x, y, and z are each independently integers from 1 to 4, R is selected from one or more of -(CH2)m-, -(CF2)n-, and -(CH2)m-(CF2)n-, and m and n are each independently integers from 1 to 20).

3. In Paragraph 2, The above R is a radical scavenger selected from one or more of -(CH2)2-(CF2)5-CF3, -(CH2)2-(CF2)7-CF3, and -(CH2)2-(CF2)9-CF3.

4. In Paragraph 2, The above M is a radical scavenger selected from one or more of Zr, Ti, Sm, Eu, Nd, Pr, and La.

5. In Paragraph 1, Radical scavenger in which the molar ratio of cerium (Ce) and metal (M) is in the range of 2:1 to 2:0.

25.

6. In Paragraph 1, Radical scavengers whose size of the above organic-inorganic hybrid nanoparticles is in the range of 1.0 to 40 nm.

7. In Paragraph 1, The above organic-inorganic hybrid nanoparticles are radical scavengers capable of nano-sized redispersion in an organic solvent or ionomer. 8.i) A step of preparing a solution comprising a fluorosilane compound containing an alkyl group or an alkoxy group and an oxide precursor of a metal selected from one or more transition metals or lanthanides: ii) a step of preparing organic-inorganic hybrid nanoparticles through a hydro-condensation reaction by adding a cerium oxide precursor to the above solution; and iii) A method for manufacturing a radical scavenger comprising the step of adding a basic solution to the above solution to precipitate and separate nanoparticles.

9. In Paragraph 8, A method for manufacturing a radical scavenger, further comprising the step of drying the nanoparticles separated in step iii) above to produce nanoparticles in a fine powder state.

10. In Paragraph 8, A method for manufacturing a radical scavenger in which the above transition metal or lanthanide is selected from one or more of Zr, Ti, Sm, Eu, Nd, Pr, and La.

11. In Paragraph 8, A method for manufacturing a radical scavenger, wherein the molar ratio of an oxide precursor of a metal selected from one or more of the above transition metals and lanthanides to the above cerium oxide precursor is in the range of 2:1 to 2:0.

25.

12. In Paragraph 8, A method for preparing a radical scavenger in which the above basic solution is one or more selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and aqueous ammonia solution.

13. Electrolyte membrane comprising a radical scavenger according to paragraph 1.

14. In Paragraph 13, The above electrolyte membrane is an electrolyte membrane containing a radical scavenger that is applied to hydrogen electric vehicle fuel cells, power generation fuel cells, PEM water electrolysis, ALK water electrolysis, AEM water electrolysis, and ammonia electrolysis cells.

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