Highly dispersible radical scavenger with low elution and reversible regenerability, and electrode composition comprising same

Abstract

The present invention relates to a highly dispersible organic-inorganic hybrid nanoparticle radical scavenger having excellent low elution characteristics and reversible regenerability and to an electrode composition comprising same, the highly dispersible organic-inorganic hybrid nanoparticle radical scavenger comprising nanoparticles in which an oxide of cerium (Ce) and silicon (Si) and an oxide of at least one metal (M) selected from transition metals and lanthanides are combined, wherein the nanoparticles have at least one functional group selected from an alkylsulfonic acid group and a fluoroalkylsulfonic acid group.

Description

A highly dispersible radical scavenger having low dissolution and reversible regeneration capabilities and an electrode composition 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 said radical scavenger, and a highly durable electrode. The present invention is characterized by further improving the electrochemical performance of an electrode by introducing a heterogeneous organic molecular structure, which has a chemical structure different from that of the electrode ionomer, into metal oxide nanoparticles and utilizing them as radical scavengers.

[0002] Electrodes, 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 and hydrogen permeated through a reinforced composite membrane due to corrosion of metal components constituting the fuel cell system, thereby producing reactive oxygen species (ROS). To suppress the generation of such radicals, a method of introducing radical scavengers into the ionomer for the electrode has been proposed.

[0003] There are cases where cerium-based metal salt compounds such as Ce(NO3)3 and Ce(OH)4 are introduced into ionomers 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 chains and cerium ions, and there are problems such as Ce 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 electrodes, mechanical properties deteriorate due to low compatibility, which may lead to cracking or fracture, and gas barrier properties may also be reduced. Consequently, to improve the dispersion stability of metal oxide nanoparticles, additional surfactants or dispersants must be added, 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 designed to ensure uniform dispersibility within binder ionomers used for electrode fabrication by minimizing spontaneous aggregation without using additives such as surfactants or dispersants. Furthermore, research is being conducted on the fabrication of high-performance electrodes and MEAs utilizing radical scavenger nanoparticles that possess continuous radical decomposition capabilities and can resolve the issue of metal ion leaching during electrochemical cell operation.

[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 electrode composition containing a highly dispersible radical scavenger, an ionomer for electrodes, an electrode using the same, and a membrane electrode assembly.

[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 alkylsulfonic acid groups and fluoroalkylsulfonic acid 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 -(CH2)mSO3H, -(CF2)nSO3H, and -(CH2)m-(CF2)n-SO3H, and m and n are each independently integers from 1 to 20).

[0014] The above R may be one or more selected from -(CH2)3-SO3H, -(CH2)5-SO3H, -(CF2)3-SO3H, -(CH2)2-(CF2)5-SO3H, and -(CH2)3-(CF2)-SO3H, 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 organic-inorganic hybrid radical scavenger according to the example may be capable of nano-sized redispersion 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 silane compound containing a thiol group (-SH) 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 a 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 the radical scavenger.

[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] According to the example, it is preferable that the perfluorinated sulfonic acid ionomer includes a radical scavenger having an alkylsulfonic acid group.

[0028] According to the example, it is preferable that the hydrocarbon-based sulfonic acid ionomer includes a radical scavenger having a fluoroalkylsulfonic acid group.

[0029] Another aspect of the present invention provides an electrode composition comprising an organic-inorganic hybrid nanoparticle radical scavenger. The electrode composition may be prepared using an ionomer dispersion containing organic-inorganic hybrid nanoparticles.

[0030] The above electrode composition 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 electrode composition containing the above radical scavenger may be used to form a membrane electrode assembly (MEA) or a zero-gap electrode and may be included in an electrochemical cell.

[0031] 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.

[0032] In addition, the organic-inorganic hybrid radical scavenger nanoparticles of 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, so they can be effectively applied to an electrode manufacturing process having uniform activity.

[0033] Since it contains ion-conductive functional groups (e.g., sulfonic acid groups, -SO3-), it can offset or improve the reduction in ion conductivity that occurs incidentally when using a binder with a reduced content of ion-conductive functional groups to enhance gas permeability, thereby improving electrochemical performance in the medium current density region (ohmic resistance region). Furthermore, by introducing heterogeneous organic molecular structures different from the ionomer chemical structure into nanoparticles, the interfaces formed due to differences in heterogeneity can be utilized as porous structures for rapid gas permeability, thereby improving electrochemical performance in the high current density region (mass transfer resistance region). This can contribute to the fabrication of electrodes with improved electrochemical cell performance.

[0034] In particular, when an organic-inorganic hybrid radical scavenger manufactured according to the present invention is applied to an electrode for application in an electrochemical cell, metal ions having radical scavenging functions 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.

[0035] Figure 1 is a schematic diagram showing the chemical structure of organic-inorganic hybrid nanoparticles prepared according to an embodiment of the present invention.

[0036] Figure 2 is a graph showing the results of the oxidation stability evaluation of electrode ionomers prepared according to comparative examples and examples.

[0037] Figure 3 is a graph showing the IV performance measurement results of MEA manufactured according to the comparative example and the example.

[0038] 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.

[0039] The organic-inorganic hybrid nanoparticle type radical scavenger according to the embodiment is designed to minimize spontaneous aggregation of nanoparticles when introduced into an aqueous alcohol solution containing an ionomer or an ionomer / electrode catalyst dispersed therein, without using additives such as surfactants or dispersants, and by including an organic molecular structure (e.g., R = -(CH2)3-SO3H) containing an ion-conducting functional group (e.g., -SO3H) that has chemical structural similarity to the fluorine-based / hydrocarbon-based ionomer used as a binder for electrode manufacturing. This ensures uniform dispersion within the ionomer after electrode molding. Furthermore, the radical scavenger nanoparticles are designed to offset or improve the reduction in ion conductivity that occurs incidentally when an ionomer with a reduced ion-conducting functional group content is used as a binder to improve gas permeability, thereby enhancing electrochemical performance in the medium current density region (ohmic resistance region).

[0040] In addition, the organic-inorganic hybrid nanoparticle type radical scavenger according to the embodiment can improve electrochemical performance in the high current density region (mass transfer resistance region) by introducing a heterogeneous organic molecular structure (e.g., R = -(CH2)3-SO3H) different from the ionomer chemical structure, thereby utilizing the interface formed due to the difference in heterogeneity as a porous structure for rapid gas permeation. For example, if the chemical structure of the ionomer used as an electrode binder is fluorine-based, the R group can introduce a hydrocarbon-based organic molecular structure, and if the chemical structure of the ionomer is hydrocarbon-based, the R group can introduce a fluorine-based organic molecular structure.

[0041] In addition, the organic-inorganic hybrid type nanoparticles according to the embodiment have a reactive scavenger function under acidic conditions against metal ions (e.g., cerium ions, Ce 3 + The phenomenon of easy leaching from the ionomer in the electrolyte membrane introduced by ) (“Cerium migration”) is shielded through an 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 electrode.

[0042] In addition, the organic-inorganic hybrid type lycal 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 the hybrid nanoparticles and applied to the electrode, and continuous radical decomposition capability can be secured when operating an electrochemical cell including the electrode.

[0043] 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 alkylsulfonic acid groups and fluoroalkylsulfonic acid groups.

[0044] 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 one or more functional groups selected from alkylsulfonic acid groups and fluoroalkylsulfonic acid groups.

[0045] The above organic-inorganic hybrid nanoparticles may be represented by the following [Chemical Formula 1].

[0046] [Chemical Formula 1]

[0047] CeOx-MOy-SiOz-R

[0048] (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)mSO3H, -(CF2)nSO3H, and -(CH2)m-(CF2)n-SO3H, and m and n are each independently integers from 1 to 20).

[0049] The above R may be one or more selected from, for example, -(CH2)3-SO3H, -(CH2)5-SO3H, -(CF2)3-SO3H, -(CH2)2-(CF2)5-SO3H, and -(CH2)3-(CF2)-SO3H, but is not limited thereto.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The organic-inorganic hybrid radical scavenger according to the example may be capable of nano-sized redispersion in an organic solvent or ionomer.

[0054] Another aspect of the present invention provides a method for producing a radical scavenger comprising: i) preparing a solution comprising a silane compound containing a thiol group (-SH) 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.

[0055] 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.

[0056] 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.

[0057] Examples of silane compounds containing a thiol group include one or more selected from 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 2-mercaptoethyltrimethoxysilane, mercaptomethyltriethoxysilane, and 4-mercaptobutyltrimethoxysilane, but are not limited thereto.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] Therefore, when an electrode composition 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.

[0066] The ionomers that can be used to manufacture the above electrode composition 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] It is undesirable for the above nanoparticles to be added to the ionomer in an amount exceeding 20 weight%, as this is highly likely to cause a deterioration in mechanical properties. When an ionomer with flexible properties is mixed with an excess amount of nanoparticles, it becomes brittle and easily breaks or loses flexibility, making it difficult to use as an electrode binder.

[0073] The above ionomer may be one or more selected from perfluorinated sulfonic acid ionomers, partially fluorinated sulfonic acid ionomers, or hydrocarbon sulfonic acid ionomers, but is not limited thereto.

[0074] According to the example, it is preferable that the perfluorinated sulfonic acid ionomer includes a radical scavenger having an alkylsulfonic acid group.

[0075] According to the example, it is preferable that the hydrocarbon-based sulfonic acid ionomer includes a radical scavenger having a fluoroalkylsulfonic acid group.

[0076] Another aspect of the present invention provides an electrode composition comprising a radical scavenger. The electrode composition may be prepared using an ionomer dispersion comprising an organic-inorganic hybrid nanoparticle radical scavenger.

[0077] The electrode of the electrochemical cell can be formed by applying a slurry mixed with a catalyst and an ionomer binder to one or both sides of an ion exchange membrane. Here, the catalyst may be one in which a metal is adsorbed onto the surface of a carbon-based support, for example, Pt / C may be used. Specifically, an electrode composition containing a radical scavenger according to the embodiment can be mixed into the catalyst slurry using a binder, and the electrode can be formed by applying this to one or both sides of an ion exchange membrane. In addition, the electrode composition can be utilized to form a cathode and / or anode in a membrane electrode assembly without any particular restrictions.

[0078] In addition, the electrode composition containing radical scavengers can be used to form zero-gap electrodes in the form of metal mesh or porous foam, in addition to the above-mentioned membrane electrode assembly (EMA), and has high potential for utilization as there are no restrictions on the type of electrode to which it is applied.

[0079] The electrode formed using the above electrode composition 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 and can be applied to various electrochemical cells.

[0080] 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.

[0081] Example 1 (Z-SRS1-containing fluorine-based ionomer)

[0082] A. Preparation of Organic-Inorganic Hybrid Nanoparticles (SRS)

[0083] 0.95 g of 3-mercaptopropyltrimethoxysilane 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 by stirring in an oil bath at 60°C for 12 hours, after which Ce(NO₃)₃·6H₂O was added to the solution and stirred until a homogeneous phase was formed, and the reaction was carried out by stirring in an oil bath at 60°C for 12 hours.

[0084] 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-SRS1) powder.

[0085] B. Preparation of Ionomer Dispersion for Electrodes

[0086] An electrode ionomer dispersion was prepared by adding 0.06 g of Z-NRS1 powder prepared in the above example 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 repeating the process of mixing using a stirrer and ultrasonizing using sonication for 6 hours.

[0087] C. Preparation of test membrane coupons

[0088] To evaluate the basic properties of the ionomer for electrodes, residual bubbles in the dispersion were removed by sonication and ultrasonically treated, and then cast onto a hydrophilized glass plate at room temperature and solidified by drying in a convection oven set to 50 degrees for 3 hours, after which a membrane coupon was manufactured by raising the temperature to 215 degrees and subjecting it to a heat treatment process for 30 minutes.

[0089] D. Preparation of Membrane Electrode Assembly (MEA)

[0090] 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, the electrode ionomer dispersion containing the organic-inorganic hybrid nanoparticles prepared above was added to the catalyst slurry and mixed for an additional 30 minutes. A commercial perfluorosulfonic acid ionomer electrolyte membrane (thickness 25 μm, Chemours, USA) was prepared in a size of 7 cm x 7 cm to have 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.

[0091] Example 2 (Z-SRS2-containing fluorine-based ionomer)

[0092] Organic-inorganic hybrid nanoparticles (Z-SRS2), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.90 g of 3-mercaptopropyltrimethoxysilane and 0.10 g of zirconium (IV) propoxide were used.

[0093] Example 3 (Z-SRS3-containing fluorinated ionomer)

[0094] Organic-inorganic hybrid nanoparticles (Z-SRS3), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.85 g of 3-mercaptopropyltrimethoxysilane and 0.15 g of zirconium (IV) propoxide were used.

[0095] Example 4 (Z-SRS4-containing fluorinated ionomer)

[0096] Organic-inorganic hybrid nanoparticles (Z-SRS4), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.80 g of 3-mercaptopropyltrimethoxysilane and 0.20 g of zirconium (IV) propoxide were used.

[0097] Example 5 (Z-SRS5-containing fluorinated ionomer)

[0098] Organic-inorganic hybrid nanoparticles (Z-SRS5), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 2-mercaptoethyltrimethoxysilane and 0.05 g of zirconium (IV) propoxide were used.

[0099] Example 6 (Z-SRS6 containing fluorine-based ionomer)

[0100] Organic-inorganic hybrid nanoparticles (Z-SRS6), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of mercaptomethyltriethoxysilane and 0.05 g of zirconium (IV) propoxide were used.

[0101] Example 7 (Z-SRS7-containing fluorinated ionomer)

[0102] Organic-inorganic hybrid nanoparticles (Z-SRS7), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 4-mercaptobutyltrimethoxysilane and 0.05 g of zirconium (IV) propoxide were used.

[0103] Example 8 (T-SRS1-containing fluorine-based ionomer)

[0104] Organic-inorganic hybrid nanoparticles (A-SRS1), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 3-mercaptopropyltrimethoxysilane and 0.05 g of titanium isopropoxide were used.

[0105] Example 9 (T-SRS2-containing fluorinated ionomer)

[0106] Organic-inorganic hybrid nanoparticles (A-SRS2), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.90 g of 3-mercaptopropyltrimethoxysilane and 0.10 g of titanium isopropoxide were used.

[0107] Example 10 (T-SRS3-containing fluorinated ionomer)

[0108] Organic-inorganic hybrid nanoparticles (A-SRS3), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.85 g of 3-mercaptopropyltrimethoxysilane and 0.15 g of titanium isopropoxide were used.

[0109] Example 11 (T-SRS4-containing fluorinated ionomer)

[0110] Organic-inorganic hybrid nanoparticles (A-SRS4), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.80 g of 3-mercaptopropyltrimethoxysilane and 0.20 g of titanium isopropoxide were used.

[0111] Example 12 (S-SRS1 containing fluorine-based ionomer)

[0112] Organic-inorganic hybrid nanoparticles (S-SRS1), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.95 g of 3-mercaptopropyltrimethoxysilane and 0.05 g of samarium nitrate hexahydrate were used.

[0113] Example 13 (S-SRS2-containing fluorine-based ionomer)

[0114] Organic-inorganic hybrid nanoparticles (S-SRS2), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.90 g of 3-mercaptopropyltrimethoxysilane and 0.10 g of samarium nitrate hexahydrate were used.

[0115] Example 14 (S-SRS3-containing fluorinated ionomer)

[0116] Organic-inorganic hybrid nanoparticles (S-SRS3), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.85 g of 3-mercaptopropyltrimethoxysilane and 0.15 g of samarium nitrate hexahydrate were used.

[0117] Example 15 (S-SRS4-containing fluorinated ionomer)

[0118] Organic-inorganic hybrid nanoparticles (S-SRS4), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 1, except that 0.80 g of 3-mercaptopropyltrimethoxysilane and 0.20 g of samarium nitrate hexahydrate were used.

[0119] Example 16 (Z-SRS8 containing hydrocarbon ionomer)

[0120] Organic-inorganic hybrid nanoparticles (Z-SRS8), electrode ionomer dispersion, membrane coupons, and MEA were prepared in the same manner as in Example 1, except that 0.95 g of 3-mercaptopropyltrimethoxysilane and 0.05 g of zirconium (IV) propoxide were used, and a hydrocarbon sulfonic acid ionomer (sulfonated poly(arylene ether sulfone) random copolymers, degree of sulfonation 32%) was used.

[0121] Example 17 (T-SRS5-containing hydrocarbon ionomer)

[0122] Organic-inorganic hybrid nanoparticles (T-SRS5), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 16, except that 0.95 g of 3-mercaptopropyltrimethoxysilane and 0.05 g of titanium isopropoxide were used.

[0123] Example 18 (S-SRS5 containing hydrocarbon ionomer)

[0124] Organic-inorganic hybrid nanoparticles (S-SRS5), an ionomer dispersion for electrodes, a membrane coupon, and an MEA were prepared in the same manner as in Example 16, except that 0.95 g of 3-mercaptopropyltrimethoxysilane and 0.05 g of samarium nitrate hexahydrate were used.

[0125] Comparative Example 1 (RS-free fluorine-based ionomer)

[0126] An ionomer dispersion, a membrane coupon, 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.

[0127] Comparative Example 2 (M-free RS-containing fluorine-based ionomer)

[0128] An ionomer dispersion, membrane coupon, and 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.

[0129] Comparative Example 3 (ROS-free hydrocarbon ionomer)

[0130] An ionomer dispersion, membrane coupon, and MEA were prepared in the same manner as in Example 16, except that no radical scavenger was added to the hydrocarbon-based sulfonic acid ionomer.

[0131] Comparative Example 4 (M-free RS-containing hydrocarbon ionomer)

[0132] An ionomer dispersion, membrane coupon, and MEA were prepared in the same manner as in Example 16, 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.

[0133] Test Example 1 (Dispersibility - Average Dispersion Particle Size)

[0134] A. Test Method

[0135] To evaluate the dispersibility of an ionomer dispersion containing organic-inorganic hybrid 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.

[0136] B. Test Results

[0137] 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]. Compared to Comparative Example 1 and Comparative Example 2, the average particle size of the nanoparticles in the ionomer dispersion according to the examples was found to be smaller. Specifically, the size of the nanoparticles according to the examples was found to be within a range of several nanometers, approximately 8.87 nm to 9.92 nm, in the fluorine-based ionomer, and within a range of approximately 10.80 nm to 11.82 nm in the hydrocarbon-based ionomer.

[0138] From these results, it can be confirmed that the nanoparticles according to the example have excellent dispersibility regardless of the type of ionomer (fluorine-based or hydrocarbon-based), and can be sufficiently redispersed into nanoparticle size within the ionomer dispersion, and accordingly, can be effectively applied to an electrode manufacturing process having uniform activity.

[0139] Average dispersed particle size of ionomer dispersion for electrodes [nm] Comparative Example 1 10.12 Comparative Example 2 10.10 Example 19.81 Example 28.99 Example 39.10 Example 48.87 Example 59.65 Example 69.55 Example 79.92 Example 88.91 Example 99.77 Example 108.90 Example 119.34 Example 129.12 Example 138.92 Example 149.22 Example 159.01 Comparative Example 3 12.05 Comparative Example 4 12.00 Example 16 10.80 Example 17 11.15 Example 18 11.82

[0140] Test Example 2 (Hydrogen ion conductivity of electrode ionomer)

[0141] A. Test Method

[0142] The impedance (bulk resistance) was measured using the AC four-point probe method under water conditions with a membrane coupon sample size of 1 cm x 5 cm and a measurement temperature of 65℃ (fuel cell operating temperature), within a frequency range of 1 Hz to 20 kHz, at which the Z" value on the Cole-Cole plot converges to 0, and then converted to hydrogen ion conductivity. (Hydrogen ion conductivity [S / cm], σ = L / (R x S) [L: distance between electrodes (cm), R: membrane resistance (Ω), S: membrane area (cm²) 2 )])

[0143] B. Test Results

[0144] The hydrogen ion conductivity of the membrane coupon samples prepared in the Examples and Comparative Examples was measured and is shown in [Table 3]. The samples incorporating the nanoparticles according to the Examples exhibited superior hydrogen ion conductivity when compared to the samples of Comparative Examples 1 and 2. This appears to be due to the influence of the sulfonic acid group (-SO3H), a hydrogen ion-conducting functional group present in the nanoparticles (SRS) according to the Examples, resulting in the introduction and expression of additional sulfonic acid groups in addition to the sulfonic acid groups originally possessed by the ionomer. Therefore, it can be seen that when the organic-inorganic hybrid radical scavenger nanoparticles according to the Examples are applied to an ionomer for electrodes, the problem of IV performance degradation caused by reduced hydrogen ion conductivity (loss in the medium current density region versus ohmic resistance region) does not occur.

[0145] Ionomer Hydrogen Ion Conductivity for Electrodes (S / cm @ 65℃) Comparative Example 10.142 Comparative Example 20.149 Example 10.162 Example 20.168 Example 30.165 Example 40.162 Example 50.167 Example 60.171 Example 70.170 Example 80.172 Example 90.169 Example 100.169 Example 110.161 Example 120.165 Example 130.170 Example 140.169 Example 150.171 Comparative Example 30.160 Comparative Example 40.167 Example 160.181 Example 170.179 180.180

[0146] Test Example 3 (Hydrogen gas permeability of electrode ionomer)

[0147] A. Test Method

[0148] A square membrane coupon sample measuring 2 cm × 2 cm (active area 1 cm × 1 cm) was injected with a gas pressure of 1 atm using the time-lag method to measure the change in gas pressure permeating / diffusing through the membrane per hour. Oxygen gas permeability was measured based on the time-lag method at △P = 1 atm and a measurement temperature of 65℃ (fuel cell operating temperature).

[0149] B. Test Results

[0150] The hydrogen gas permeability of membrane coupon samples prepared in the Examples and Comparative Examples was measured and is shown in [Table 3]. The samples with nanoparticles introduced according to the Examples showed improved hydrogen gas permeability when compared to the samples of Comparative Examples 1 and 2. This appears to be the effect of maximizing gas permeability through the interface formed due to differences in heterogeneity by introducing organic chains that have chemical structural heterogeneity with the ionomer according to the type of ionomer applied (fluorine-based or hydrocarbon-based). Therefore, it can be seen that applying the nanoparticle dispersion according to the Examples as an ionomer for electrodes can contribute to the improvement of IV performance by improving gas permeability (minimizing losses in the high current density region versus mass transfer resistance region).

[0151] Oxygen Gas Permeability of Ionomer Electrode [Barrer @ 65℃] Comparative Example 15.02 Comparative Example 25.08 Example 15.40 Example 25.50 Example 35.66 Example 45.45 Example 55.44 Example 65.56 Example 75.63 Example 85.52 Example 95.51 Example 105.56 Example 115.49 Example 125.51 Example 135.55 Example 145.48 Example 155.66 Comparative Example 30.36 Comparative Example 40.37 Example 160.69 Example 170.66 Example 180.70

[0152] Test Example 4 (Oxidation stability of electrode ionomer)

[0153] A. Oxidation Stability of Electrode Iomers

[0154] A Fenton reagent was prepared by reacting 0.1 wt.% ferrous ammonium sulfate with 30 wt.% hydrogen peroxide, and a square membrane coupon 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 electrode ionomer as follows.

[0155] 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).

[0156] When applying hydrocarbon-based ionomers, the oxidation stability of the electrode ionomer was evaluated by calculating the weight loss rate through weight measurements before and after the Fenton test.

[0157] B. Test Results

[0158] Figure 2 shows the results of evaluating the oxidation stability of membrane coupon samples according to Examples 1 to 15 (E1 to E15) and Comparative Examples (C1 to C2).

[0159] Compared to Comparative Example 1 (C1), the concentration of fluoride ions released from the membrane coupon samples of Comparative Example 2 (C2) and Examples (E1–E15) was found to be lower. In particular, the membrane coupon samples into which nanoparticles according to the Examples were introduced showed significantly lower fluoride ion concentrations. This is because regeneration (Ce) was achieved by introducing transition metal / lanthanide-based metal oxides into the preparation of organic-inorganic hybrid nanoparticles. 3 + / Ce 4 + redox cycling is seen as a maximized effect.

[0160] In addition, to evaluate the oxidation stability of membrane coupon samples to which hydrocarbon-based ionomers were applied according to Examples 16 to 18 and Comparative Examples 3 to 4, the weight loss rate was measured and is shown in [Table 4]. The membrane coupon sample of Comparative Example 3 exhibited the highest weight loss rate, and it was confirmed that it was partially lost when the Fenton test was completed. Compared to Comparative Example 3, the samples of Comparative Example 4 and Examples 16 to 18 showed lower weight loss rates after the Fenton test. In particular, the membrane coupon samples to which nanoparticles according to the examples were introduced showed significantly lower weight loss rates. This is because regeneration (Ce) is achieved by introducing transition metal / lanthanide-based metal oxides into the preparation of organic-inorganic hybrid nanoparticles. 3 + / Ce 4 + It demonstrates that the oxidation stability of electrode ionomers is improved through the maximized effect of redox cycling.

[0161] Ionomer weight loss rate for electrodes [%] Comparative Example 3 38.8 Comparative Example 4 26.2 Example 16 15.9 Example 17 16.1 Example 18 17.8

[0162] Test Example 5 (IV performance of electrode ionomer)

[0163] A. Measurement of MEA IV Performance

[0164] Active area 25 cm 2 The IV performance of an MEA with an electrode ionomer applied was measured under conditions of an operating temperature of 65℃, RH = 100 / 100 %, and P = 1.0 bar.

[0165] B. Test Results

[0166] Figure 3 shows the results of measuring the IV performance of MEAs with electrode ionomers according to the examples and comparative examples. The MEAs with nanoparticles introduced according to Examples 1, 8, and 12 (E1, E8, E12) showed superior IV performance compared to Comparative Example 1 (C1) and Comparative Example 2 (C2), regardless of the type of transition metal / lanthanide metal. This appears to be a combined effect resulting from improved hydrogen ion conductivity (minimization of loss in the medium current density-ohmic resistance region) and improved gas permeability (minimization of loss in the high current density-mass transfer resistance region) through the introduction of organic-inorganic hybrid nanoparticles (SRS) containing sulfonic acid groups (-SO3H), which are hydrogen ion conductive functional groups, as well as uniform dispersion.

[0167] Test Example 6: Durability and Ce leaching stability of electrode ionomer

[0168] A. Test Method

[0169] A-1. Durability of Ionomers for Electrodes

[0170] Accelerated electrode layer degradation was induced by repeatedly performing a process of stepwise decreasing the OCV from 0.35 V at a rate of 25 mA / sec for 50 hours under conditions of an operating temperature of 70℃, RH = 100 / 100%, and SR: H2 / O2:1.5 / 2.0. IV performance was measured before and after degradation under conditions of an operating temperature of 65℃, RH = 100 / 100%, P = 1.0 bar, and SR: H2 / O2:1.5 / 2.0, and the performance retention rate relative to initial performance was calculated. (Performance retention rate [%] = (Performance after endurance / Initial performance) X 100)

[0171] A-2. Ce dissolution stability

[0172] The Ce content was measured using X-ray fluorescence spectrometry (XRF) before and after accelerated endurance to observe the change in Ce content after endurance relative to the initial Ce introduction amount of the radical scavenger, and the Ce dissolution stability in the radical scavenger was evaluated through the analysis of Ce loss amount.

[0173] B. Test Results

[0174] The durability test results of MEAs with electrode ionomers according to the Examples and Comparative Examples are shown in [Table 5]. Comparative Example 1 showed the lowest performance retention rate of 85% due to post-endurance performance being lower than the initial performance after the endurance test ended, while Comparative Example 2 showed a performance retention rate of 88%, which is approximately 3% higher than Comparative Example 1. In the Examples, a high performance retention rate of 93.1% to 95.0% was confirmed regardless of the type of transition metal / lanthanide metal. This is attributed to uniform activity secured through even distribution within the electrode due to high dispersibility, and the Ce on the nanoparticle surface through metal ion bonding by introducing transition metal / lanthanide metal oxides into the preparation of organic-inorganic hybrid nanoparticles. 3 + Minimization of content loss and long-term reversible regenerative functionality (Ce 3 + / Ce 4 + It appears to be an effect that maximizes redox cycling.

[0175] Classification Initial current density [A / cm² 2 @0.6 V] Current density after endurance [A / cm² 2 @0.6 V]Performance Retention Rate[%]Ce Elution Stability (Ce Loss Rate) [%] Comparative Example 11.6941.44385.3- Comparative Example 21.8041.58988.116.9 Example 11.9661.83093.110.5 Example 82.0041.90495.010.1 Example 121.9851.86493.910.3

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 alkylsulfonic acid groups and fluoroalkylsulfonic acid groups.

2. In Paragraph 1, Radical scavenger comprising 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 -(CH2)mSO3H, -(CF2)nSO3H, and -(CH2)m-(CF2)n-SO3H, and m and n are each independently integers from 1 to 20).

3. In Paragraph 2, The above R is a radical scavenger comprising one or more selected from -(CH2)3-SO3H, -(CH2)5-SO3H, -(CF2)3-SO3H, -(CH2)2-(CF2)5-SO3H, and -(CH2)3-(CF2)-SO3H.

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 2, 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 silane compound containing a thiol group (-SH) and an oxide precursor of one or more metals selected from 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. An electrode composition comprising a radical scavenger according to claim 1.

14. In Paragraph 13, The above electrode composition is an electrode composition 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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