KR20230034881A - Radical scavenger, method for manufacturing the same, and membrane-electrode assembly comprising the same - Google Patents

Abstract

The present invention relates to a radical scavenger including particles capable of trapping peroxides or radicals and a fluorine-based polymer introduced to at least a part of the outer surface and inside of the particles, a method for manufacturing the same, and a membrane-electrode assembly including the same. The present invention can improve dispersibility by preventing the aggregation of the radical scavenger itself.

Description

Radical scavenger, method for manufacturing the same, and membrane-electrode assembly including the same

The present invention relates to a radical scavenger, a method for manufacturing the same, and a membrane-electrode assembly including the same, and more specifically, to prevent elution of the radical scavenger and aggregation between particles during a fuel cell driving process to increase dispersibility It relates to a radical scavenger capable of maintaining the performance of a fuel cell for a long period of time and improving its lifespan, a manufacturing method thereof, and a membrane-electrode assembly including the same.

A fuel cell is a battery equipped with a power generation system that directly converts chemical reaction energy such as oxidation/reduction reaction of hydrogen and oxygen contained in hydrocarbon-based fuel materials such as methanol, ethanol, and natural gas into electrical energy. Due to its efficiency and eco-friendly characteristics with low pollutant emissions, it is attracting attention as a next-generation clean energy source that can replace fossil energy.

Such a fuel cell has the advantage of being able to produce a wide range of outputs in a stack configuration by stacking unit cells, and it is attracting attention as a small and mobile portable power source because it shows an energy density 4 to 10 times higher than that of a small lithium battery. there is.

A stack that actually generates electricity in a fuel cell is a stack of several to dozens of unit cells composed of a membrane-electrode assembly (MEA) and a separator (also called a bipolar plate). The membrane-electrode assembly generally has a structure in which an anode (or fuel electrode) and a cathode (cathode, or air electrode) are formed on both sides of the electrolyte membrane.

Fuel cells can be classified into alkaline electrolyte fuel cells and polymer electrolyte membrane fuel cells (PEMFC) depending on the state and type of electrolyte. Among them, polymer electrolyte fuel cells have a low operating temperature of less than 100 ℃ Due to its advantages such as fast start-up, response characteristics and excellent durability, it is in the limelight as a portable, vehicle and home power supply.

Representative examples of polymer electrolyte fuel cells include a Proton Exchange Membrane Fuel Cell (PEMFC) that uses hydrogen gas as fuel, and a Direct Methanol Fuel Cell (DMFC) that uses liquid methanol as fuel. etc. can be mentioned.

Summarizing the reaction occurring in the polymer electrolyte fuel cell, first, when a fuel such as hydrogen gas is supplied to the anode, hydrogen ions (H ⁺ ) and electrons (e ^- ) are generated by the oxidation reaction of hydrogen at the anode. . The generated hydrogen ions are transferred to the cathode through the ion exchange membrane, and the generated electrons are transferred to the cathode through the external circuit. At the cathode, oxygen is supplied, and oxygen is combined with hydrogen ions and electrons to produce water by a reduction reaction of oxygen.

On the other hand, in order to realize the commercialization of polymer electrolyte fuel cells, there are still many technical barriers to be solved, and essential improvement factors are realization of high performance, long lifespan, and low price. The component that has the most influence on this is the membrane-electrode assembly, and among them, the ion exchange membrane is one of the key elements that have the greatest influence on the performance and price of the MEA.

Requirements for the ion exchange membrane required for the operation of the polymer electrolyte fuel cell include high hydrogen ion conductivity, chemical stability, low fuel permeability, high mechanical strength, low moisture content, and excellent dimensional stability. Conventional ion exchange membranes tend to be difficult to normally exhibit high performance under specific temperature and relative humidity conditions, particularly under high temperature/low humidity conditions. Due to this, the polymer electrolyte fuel cell to which the conventional ion exchange membrane is applied is limited in its use range.

Fluorine-based ion exchange membranes such as Nafion, which are currently known to exhibit the best performance, have limitations due to complexity of manufacturing process, difficulty in manufacturing technology, and high price. There are still many technical barriers to be overcome due to problems such as low hydrogen ion conductivity under low humidity conditions, non-uniform interfacial properties, and relatively poor durability.

In addition, such an ion exchange membrane requires high ion conductivity and excellent durability at the same time. In particular, when the fuel cell is operated for a long period of time, deterioration of the fuel cell occurs due to decrease in the thickness of the electrolyte membrane and formation of pin-holes due to the weak chemical durability of the ion exchange membrane.

Radicals generated when the fuel cell is operated are known to be the main cause of deterioration of the polymer electrolyte membrane. For example, during the reduction reaction of oxygen at the reducing electrode, hydrogen peroxide (H ₂ O ₂ ) is generated, and from this hydrogen peroxide, a hydrogen peroxide radical (HO ₂ ) and / or a hydroxyl radical ( OH ) can be created. In addition, when oxygen molecules in the air supplied to the cathode pass through the polymer electrolyte membrane and reach the anode, hydrogen peroxide is also generated at the anode, resulting in hydrogen peroxide radicals and/or hydroxyl radicals. These radicals cause deterioration of ionomer (for example, a polymer having a sulfonic acid group) included in the polymer electrolyte membrane, thereby lowering the ionic conductivity of the electrolyte membrane.

In order to prevent deterioration of a polymer electrolyte membrane (more specifically, an ionomer) due to radicals, introduction of a radical scavenger capable of removing the radicals has been proposed.

However, there is a problem in that the radical scavenger dispersed in the electrolyte membrane in the form of particles migrates during operation of the fuel cell. That is, since the amount of radical scavengers capable of removing radicals is reduced, as the driving time of the fuel cell increases, radical removal is not properly performed, resulting in rapid performance degradation of the fuel cell.

In addition, metal ions generated through ionization of radical scavengers are eluted by water. Since this metal ion has a very high reduction potential, it oxidizes the components of the electrode (eg, platinum and/or carbon), causing degradation of the performance of the fuel cell.

Therefore, there is an urgent need to develop a radical scavenger for preventing elution of such radical scavengers and preventing elution of metal ions generated through ionization thereof.

An object of the present invention is to prevent elution of radical scavengers during fuel cell operation and prevent aggregation between radical scavenger particles to increase dispersibility, thereby maintaining the performance of fuel cells for a long time and improving their lifespan It is to provide a radical scavenger.

Another object of the present invention is to provide a method for preparing the radical scavenger.

Another object of the present invention is to provide a membrane-electrode assembly including the radical scavenger.

One embodiment of the present invention provides a radical scavenger including particles capable of trapping peroxides or radicals and a fluorine-based polymer introduced into at least a part of the outer surface and the inside of the particles.

The particles may include at least one selected from the group consisting of transition metals, noble metals, ions thereof, salts thereof, oxides thereof, nitrides thereof, and complexes thereof.

The fluorine-based polymer may be poly(perfluorosulfonic acid), a copolymer of sulfonic acid group-containing tetrafluoroethylene and fluorovinyl ether, or a mixture thereof.

The particles may be porous particles including a plurality of pores, and the pores of the particles may be impregnated with the fluorine-based polymer.

A coating layer may be included on the outer surface of the particle, and the coating layer may include the fluorine-based polymer.

The coating layer may be formed in an area of 30% to 70% of the total external surface area of the particle.

The particles may have an average particle diameter of 50 nm to 1 μm.

The thickness of the coating layer may be 5% to 30% of the average particle diameter range of the particles.

A relative degree of crystallinity (RDOC) of the coating layer may be 10.0% to 16.0%.

The content of the particles may be 30 to 80% by weight based on the total weight of the radical scavenger.

In another embodiment of the present invention, preparing particles capable of trapping peroxides or radicals, introducing a fluorine-based polymer to at least a part of the outer surface and inside of the particles, and heat-treating the particles into which the fluorine-based polymer is introduced It provides a method for producing a radical scavenger comprising the step of doing.

The particles may be porous particles formed by a one-pot hydrothermal synthesis method, a sol-gel method, or a cavity formation method by redox.

The fluorine-based polymer may be poly(perfluorosulfonic acid), a copolymer of sulfonic acid group-containing tetrafluoroethylene and fluorovinyl ether, or a mixture thereof.

In the step of introducing the fluorine-based polymer, the dispersion or melt of the fluorine-based polymer is mixed with the particles and then sprayed, and the mixing is performed using a homogeneous mixer, a high-pressure disperser, a ball mill, a powder mixer, ultrasonic mixing, and resonance It may be performed using at least one selected from the group consisting of acoustic mixing.

The heat treatment may be performed at 120 °C to 220 °C. In addition, the heat treatment may be performed for 1 minute to 5 hours.

A step of immersing the particles into which the fluorine-based polymer is introduced after the heat treatment may be further included in an acidic aqueous solution.

The particles may include at least one selected from the group consisting of transition metals, noble metals, ions thereof, salts thereof, oxides thereof, nitrides thereof, and complexes thereof.

The content of the particles may be 30 to 80% by weight based on the total weight of the radical scavenger.

Another embodiment of the present invention is a group consisting of an ion exchange membrane, a catalyst electrode disposed on both sides of the ion exchange membrane, and within the catalyst electrode, within the ion exchange membrane, between the ion exchange membrane and the catalyst electrode, and combinations thereof. A membrane-electrode assembly including the radical scavenger at a selected location is provided.

The membrane-electrode assembly may further include an interfacial adhesion layer positioned between the ion exchange membrane and the catalyst electrode, and the interfacial adhesion layer may include an ionomer and the radical scavenger.

The interfacial bonding layer may include 0.1 wt% to 70 wt% of the radical scavenger based on the total weight of the interfacial bonding layer.

The interfacial adhesive layer may have a thickness of 5 nm to 5 μm.

The loading amount of the interfacial adhesive layer may be 0.01 mg/cm ² to 2.0 mg/cm ² .

Another embodiment of the present invention provides a fuel cell including the membrane-electrode assembly.

According to the present invention, by introducing a fluorine-based polymer to the outer surface or inside of the radical scavenger, the mobility of the radical scavenger itself can be reduced to suppress elution, as well as the aggregation of the radical scavenger itself. can be prevented to improve dispersibility.

Therefore, the performance of the fuel cell can be maintained for a long period of time without chemical deterioration of the electrolyte membrane and/or the electrode due to radicals generated during operation of the fuel cell, specifically, hydroxyl radicals, and its lifespan can be remarkably improved.

1 is a schematic diagram schematically showing a radical scavenger according to an embodiment of the present invention.
2 is a schematic diagram schematically showing a radical scavenger according to an embodiment of the present invention.
3 is a schematic cross-sectional view of a membrane-electrode assembly according to an embodiment of the present invention.
4 is a schematic diagram showing the overall configuration of a fuel cell according to an embodiment of the present invention.
5 is an XRD pattern measured to confirm the crystallinity of the radical scavenger prepared in Preparation Example of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In the drawings, the thickness is enlarged in order to clearly express various layers and regions, and the same reference numerals are attached to similar parts throughout the specification. When a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly on" another part, it means that there is no other part in between.

Hereinafter, a radical scavenger according to an embodiment will be described.

The present invention prevents elution of radical scavengers during fuel cell operation and prevents aggregation between radical scavenger particles to increase dispersibility, thereby maintaining performance of fuel cells for a long period of time and improving their lifespan. It's about the Cabiner.

1 and 2 are schematic diagrams showing a schematic configuration of a radical scavenger according to an embodiment.

Specifically, the radical scavenger according to an embodiment includes particles capable of trapping peroxides or radicals, and a fluorine-based polymer introduced to at least a part of the outer surface and the inside of the particles.

Since the oxygen reduction reaction at the cathode electrode of the polymer electrolyte fuel cell proceeds via hydrogen peroxide (H ₂ O ₂ ), a hydroxyl radical (.OH) may be generated from hydrogen peroxide or the generated hydrogen peroxide at the cathode electrode. In addition, in the anode electrode of the polymer electrolyte fuel cell, as oxygen molecules pass through the ion exchange membrane, the hydrogen peroxide or hydroxyl radical may also be generated at the anode electrode. The generated hydrogen peroxide or hydroxyl radical causes deterioration of a polymer including a sulfonic acid group included in the ion exchange membrane or the catalyst electrode.

A radical scavenger capable of trapping or decomposing peroxides or radicals is applied in order to prevent deterioration of a polymer electrolyte membrane caused by peroxides or radicals commonly generated during the operation of a fuel cell. However, as the driving process of the fuel cell continues, the amount of radical scavenger that can remove radicals decreases due to the elution of radical scavengers. There was a problem that caused the degradation.

On the other hand, the radical scavenger according to the present invention reduces the mobility of the radical scavenger itself by introducing a fluorine-based polymer to at least a part of the outer surface or inside of the peroxide or radical-capturing particles, thereby driving a fuel cell. In the process, the elution of the radical scavenger is prevented and the aggregation between the radical scavenger particles is prevented to increase the dispersibility, thereby maintaining the performance of the fuel cell for a long period of time and improving its lifespan.

The particles are particles capable of removing peroxides or radicals that cause deterioration of the electrolyte membrane and thereby lower the ion conductivity, and include transition metals, noble metals, ions thereof, salts thereof, oxides thereof, nitrides thereof, and It may contain at least one selected from the group consisting of complexes.

The transition metal is cerium (Ce), manganese (Mn), tungsten (W), cobalt (Co), vanadium (V), nickel (Ni), chromium (Cr), zirconium (Zr), yttrium (Y), iridium (Ir), iron (Fe), titanium (Ti), molybdenum (Mo), lanthanum (La), or neodymium (Nd), but is not limited thereto.

The noble metal may be silver (Au), platinum (Pt), ruthenium (Ru), palladium (Pd), or rhodium (Rh), but is not limited thereto.

The ions of the transition metal or noble metal include cerium (Ce) ions, manganese (Mn) ions, tungsten (W) ions, cobalt (Co) ions, vanadium (V) ions, nickel (Ni) ions, and chromium (Cr) ions. , zirconium (Zr) ion, yttrium (Y) ion, iridium (Ir) ion, iron (Fe) ion, titanium (Ti) ion, molybdenum (Mo) ion, lanthanum (La) ion, or neodymium (Nd) ion For example, cerium may be a trivalent ion (Ce ³⁺ ) or a tetravalent ion (Ce ⁴⁺ ) of cerium.

The transition metal or precious metal salt may be a carbonate, acetate, chloride, fluoride, sulfate, phosphate, nitrate, tungstate, hydroxide, ammonium acetate, ammonium sulfate, or acetylacetonate salt, and specifically cerium as an example. Examples thereof include cerium carbonate, cerium acetate, cerium chloride, cerium acetate, cerium sulfate, cerium diammonium acetate, cerium quaternary ammonium sulfate, and the like, and cerium acetylacetonate and the like as organometallic complex salts.

The fluorine-based polymer may include poly(perfluorosulfonic acid), a copolymer of tetrafluoroethylene containing a sulfonic acid group and fluorovinyl ether, or a mixture thereof.

The fluorine-based polymer is introduced to the outer surface or inside of the particle capable of trapping the peroxide or radical, or introduced to both the outer surface and the inside to reduce and stabilize the mobility of the particle itself, driving a fuel cell In the process, elution of the particles may be prevented.

In one embodiment, the particle may be a porous particle including a plurality of pores, and the fluorine-based polymer may be impregnated into the pores of the particle.

The porous particles are, for example, by using a precursor of a transition metal or noble metal, which is a particle capable of trapping peroxides or radicals, by a one-pot hydrothermal synthesis method, a sol-gel method, or a redox method. However, it is not limited to the method as long as porosity can be imparted to the particles using the precursor.

The porous particle needs to have an appropriate pore size so that the fluorine-based polymer is appropriately impregnated into the pores of the porous particle and does not interfere with trapping or decomposing peroxides or radicals. For example, the average pore size of the porous particle is 1 nm to 20 nm.

In one embodiment, the average particle diameter of the particles may be, for example, 50 nm to 1 μm, specifically 60 nm to 100 nm. If the average particle diameter of the particles is less than 50 nm, there is a risk of elution during the fuel cell driving process, and if the average particle diameter exceeds 1 μm, the dispersibility of the radical scavenger in the particles is reduced, thereby increasing the efficiency of trapping peroxides or radicals There is a risk of decrease.

In one embodiment, a coating layer may be included on the outer surface of the particle, and the coating layer may include the fluorine-based polymer.

Since the coating layer containing the fluorine-based polymer is formed on the surface of the particles capable of trapping peroxides or radicals, the mobility of the particles is reduced and stabilized, thereby preventing the particles from eluting during operation of the fuel cell.

The coating layer may be formed to completely cover the particles, or may be formed to include a plurality of pores to cover the particles in a mesh shape.

1 and 2 are diagrams schematically showing a radical scavenger including coating layers of different shapes, respectively.

Referring to FIG. 1 , in the radical scavenger according to an embodiment, a mesh-shaped coating layer may be formed to include a plurality of pores on the surface of the peroxide or radical-capturing particles. Through a plurality of pores formed in the coating layer, for example, hydroxyl radicals ( OH ) generated during fuel cell operation pass through the plurality of pores of the coating layer and react with the peroxide or particles capable of trapping the radicals. , By discharging the reaction product through the pores, the decomposition of the hydroxyl radical can proceed smoothly. As described above, when a mesh-shaped coating layer is formed to include a plurality of pores on the surface of the particle capable of trapping the peroxide or radical of the radical scavenger, the coating layer is 30% to 70% of the total external surface area of the particle % area.

In one embodiment, the size of the pores included in the coating layer is, for example, 1 angstrom (Å) to 20 angstrom (Å) for smooth movement of radicals to be captured by the radical scavenger and reaction products of the radicals , and more specifically, it may be 3 Angstroms (Å) to 5 Angstroms (Å).

Referring to FIG. 2 , the radical scavenger according to an embodiment may be formed as a coating layer completely covering the surface of the peroxide or radical-capturing particle, for example, a core-shell type. As the coating layer is formed in the core-shell form as described above, the content of the fluorine-based polymer in the coating layer is relatively increased, and as a result, the mobility of the radical scavenger is significantly reduced and stabilized, thereby reducing the particle size during the operation of the fuel cell. There is an effect that can further prevent elution.

In one embodiment, the thickness of the coating layer may be, for example, 5% to 30%, specifically 10% to 20% of the average particle diameter range of the peroxide or radical-capturing particles.

When the thickness of the coating layer is less than 5% of the average particle diameter range of the particles, the content of the fluorine-based polymer contained in the coating layer is relatively reduced and the mobility of the particles is increased. As a result, there is a possibility that the particles are eluted during the fuel cell driving process. , If the thickness of the coating layer exceeds 30% of the average particle diameter range of the particles, the ability to capture peroxide or radicals by the particles may be reduced, so it is appropriately adjusted within the above range.

In one embodiment, the relative degree of crystallinity (RDOC) of the coating layer may be 10.0% to 16.0%, for example, 12.0% to 15.0%, preferably 13.0% to 14.5% or 13.5% to 14.3%. may be %. The radical scavenger according to an embodiment may be one in which a rigid coating layer having crystallinity is formed by applying a fluorine-based polymer to the surface of the particles capable of trapping the peroxide or radicals and heat-treating the same. Details of the heat treatment will be described later together with the method of manufacturing the radical scavenger. As the relative crystallinity of the coating layer is 10.0% to 16.0%, there is an effect of significantly reducing the stability and mobility of the radical scavenger according to one embodiment, and the relative crystallinity of the coating layer exceeds 16.0%. In this case, the ionic conductivity of the membrane-electrode assembly including the radical scavenger may decrease. The relative crystallinity of the radical scavenger coating layer according to the embodiment can be obtained from the area of the crystalline phase relative to the sum of the area of the crystalline phase and the area of the amorphous phase through, for example, X-ray diffraction (XRD) analysis results. .

In one embodiment, the particles capable of trapping the peroxide or radicals may be included in an amount of 30% to 80% by weight, specifically 40% to 70% by weight, based on the total weight of the radical scavenger. .

If the content of the particles is less than 30% by weight based on the total weight of the radical scavenger, the ability to capture or decompose peroxides or radicals of the radical scavenger may decrease, and 80% based on the total weight of the radical scavenger When the weight % is exceeded, the content of the fluorine-based polymer in the radical scavenger is relatively reduced and the mobility of the particles is increased, so that the particles may be eluted during the fuel cell driving process, so it is appropriately adjusted within the above range.

Another embodiment of the present invention is to prepare particles capable of trapping peroxides or radicals, introducing a fluorine-based polymer to at least a part of the outer surface and inside of the particles, and heat-treating the particles into which the fluorine-based polymer is introduced It provides a method for producing a radical scavenger comprising the step of doing.

The particles may include at least one selected from the group consisting of transition metals, noble metals, ions thereof, salts thereof, oxides thereof, nitrides thereof, and complexes thereof. Since it is the same as the above, repetitive explanation is omitted.

In one embodiment, the particle may be a porous particle including a plurality of pores, and the porous particle may be a one-pot using a precursor of a transition metal or noble metal, which is a particle capable of trapping a peroxide or a radical. Porosity may be imparted to the particles using a hydrothermal synthesis method, a sol-gel method, or a method of forming cavities in particles by ion switching in the oxidation-reduction reaction of the transition metal or noble metal.

The average pore size of the particles may be 1 nm to 20 nm so that the fluorine-based polymer is appropriately impregnated into the pores of the porous particles and does not interfere with trapping or decomposing peroxides or radicals.

Next, a fluorine-based polymer is introduced to at least a part of the outer surface and the inside of the particle capable of trapping the peroxide or the radical.

In one embodiment, the step of introducing the fluorine-based polymer may include mixing a dispersion of the fluorine-based polymer or a melt of the fluorine-based polymer with the particles, and then spraying the particles.

The fluorine-based polymer may include poly(perfluorosulfonic acid), a copolymer of tetrafluoroethylene containing a sulfonic acid group and fluorovinyl ether, or a mixture thereof. For example, the fluorine-based polymer is -SO ₂ X functional group (X is selected from X' or OM, X' is selected from the group consisting of F, Cl, Br and I, M is H or an alkali metal) and may include repeating units derived from tetrafluoroethylene (TFE) and linear sulfonyl fluoride vinyl ether (SFVE) F ₂ C=CF-O-CF ₂ -CF ₂ -SO ₂ F. Also, for example, the fluorine-based polymer may include a side chain represented by Formula 1 below:

[Formula 1]

In Formula 1, m and n are each independently an integer of 0 or 1 or more, A is a cation exchange group, for example, a sulfonic acid group (SO ₃ ^- H ⁺ ), and * represents a portion connected to the main chain.

Commercially available products as the fluorine-based polymer include DuPont's Nafion, 3M's ionomer (Dyneon, etc.), Solvay's Aquivion, and the like.

Examples of solvents for preparing a fluorine-based polymer dispersion by adding the fluorine-based polymer to a solvent include water, ethanol, methanol, acetone, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tris-hydrochloric acid buffer solutions and these Any one selected from the group consisting of mixtures may be used, but the type may not be limited as long as it can properly disperse the fluorine-based polymer.

Mixing of the dispersion of the fluorine-based polymer or the melt of the fluorine-based polymer with the particles is, for example, a homogeneous mixer, a high-pressure disperser, a ball mill, a powder mixer, ultrasonic mixing, and resonant acoustic mixing. Performed using at least one selected from the group consisting of It can be.

For example, mixing of the dispersion of the fluorine-based polymer or the melt of the fluorine-based polymer and the particles may be performed through a resonant acoustic mixer, wherein the resonant acoustic mixer has a power of 5 to 50% and 1 to 5 cycles ( For example, a process of operating for 10 minutes and stopping for 5 minutes is regarded as one cycle). If the driving power of the resonant acoustic mixer is less than 5% power, uniform mixing may not be achieved, and if it exceeds 50% power, agglomeration of fluorine-based polymers and / or particles may occur due to internal frictional heat or the like. .

The mixing may be performed at 0 °C to 80 °C for 0.5 hour to 50 hours, and more specifically at 20 °C to 40 °C for 8 hours to 16 hours. When the mixing is performed at less than 0° C. for less than 0.5 hours, the fluorine-based polymer and the particles may be non-uniformly mixed or the fluorine-based polymer may not be sufficiently introduced into the particles. A large amount of fluorine-based polymer may be introduced.

After the dispersion of the fluorine-based polymer or the melt of the fluorine-based polymer is mixed with the particles and then sprayed, particles into which the fluorine-based polymer is introduced may have a spherical shape and a uniform distribution. As a non-limiting example, the spray spraying may be performed by spraying the dispersion of the fluorine-based polymer or the mixture of the melt of the fluorine-based polymer and the particles at high pressure through a nozzle under appropriate spray conditions, and the average inlet temperature of the nozzle And spray conditions such as average outlet temperature, average flow rate of the mixed solution, type and diameter of the nozzle, spray pressure, etc. may be adjusted in consideration of the solid content of the mixed solution and "drying" efficiency.

When the dispersion of the fluorine-based polymer or the melt of the fluorine-based polymer and the particles are mixed, the content of the particles may be 30% to 80% by weight based on the total weight of the radical scavenger, and more specifically, 40 to 70% by weight % can be included. If the content of the particles is less than 30% by weight based on the total weight of the radical scavenger, the ability to capture or decompose peroxides or radicals of the radical scavenger may decrease, and 80% based on the total weight of the radical scavenger When the weight % is exceeded, the content of the fluorine-based polymer in the radical scavenger is relatively reduced and the mobility of the particles is increased, so that the particles may be eluted during the fuel cell driving process, so it is appropriately adjusted within the above range.

Next, heat treatment is performed to prevent the fluorine-based polymer from being dispersed in the particle into which the fluorine-based polymer is introduced on the outer surface or inside.

In one embodiment, as the heat treatment method, a method using hot air, a method using an oven, a method using IR, and the like may be used.

In one embodiment, the heat treatment may be performed at, for example, 120 °C to 220 °C, and may be appropriately adjusted within the above temperature range in consideration of the melting or denaturation temperature of the fluorine-based polymer used. For example, when the heat treatment temperature is less than 120 ° C., the fluorine-based polymer introduced into the outer surface or inside of the particle may not be effectively introduced, or may be lost from the particle after introduction, and the heat treatment temperature exceeds 220 ° C. In this case, there is a concern that the fluorine-based polymer introduced into the particles may be melted or denatured.

In addition, in one embodiment, the heat treatment time can be appropriately selected and adjusted by a person skilled in the art in consideration of the type of fluorine-based polymer used, heat treatment temperature, heat treatment method, and the like. For example, the heat treatment may be performed for 1 minute to 5 hours.

Specifically, in the case of Nafion, heat treatment may be performed at 120 ° C for 5 hours or at 220 ° C for 1 minute, in the case of 3M ionomer, heat treatment may be performed at 160 to 190 ° C for 10 minutes to 1 hour, and in the case of Solvay's Aquivion, 180 to 210° C. for 5 minutes to 1 hour.

If necessary, after the heat treatment step, the particle into which the fluorine-based polymer is introduced may be immersed in an acidic aqueous solution to replace the terminal of the sulfonyl group included in the fluorine-based polymer with an acidic functional group.

The acidic aqueous solution may be an aqueous solution of an acidic solution such as sulfuric acid, hydrochloric acid, or nitric acid, and preferably, a 0.2 to 0.5 M sulfuric acid aqueous solution may be used. The process may proceed by immersing the fluorine-based polymer in an acidic aqueous solution at about 60 °C to 100 °C for about 5 minutes to 30 minutes.

Through the method for preparing the radical scavenger, a fluorine-based polymer is introduced to at least a part of the outer surface and the inside of the peroxide or radical-capturing particles, thereby forming an ion exchange membrane in a fuel cell, a catalyst electrode, or the ion exchange membrane and a catalyst electrode. It may be formed so as not to be eluted from the interfacial adhesive layer between them.

A membrane-electrode assembly according to another embodiment of the present invention includes an ion exchange membrane, a catalyst electrode disposed on both sides of the ion exchange membrane, and within the catalyst electrode, within the ion exchange membrane, between the ion exchange membrane and the catalyst electrode, and between the catalyst electrode and the catalyst electrode. It includes the radical scavenger at any one position selected from the group consisting of combinations.

3 is a schematic cross-sectional view of the membrane-electrode assembly.

Referring to FIG. 3 , the membrane-electrode assembly 100 includes the ion exchange membrane 50 and electrodes 20 and 20' disposed on both sides of the ion exchange membrane 50, respectively. The electrodes 20 and 20' include electrode substrates 40 and 40' and catalyst electrodes 30 and 30' formed on surfaces of the electrode substrates 40 and 40', and the electrode substrates 40 and 40' ) And a microporous layer (not shown) containing conductive fine particles such as carbon powder and carbon black to facilitate material diffusion in the electrode substrates 40 and 40' between the catalytic electrodes 30 and 30'. ) may be further included.

In the membrane-electrode assembly 100, an oxidation reaction in which hydrogen ions and electrons are generated from fuel disposed on one surface of the ion exchange membrane 50 and transferred to the catalyst electrode 30 through the electrode substrate 40 The electrode 20 that causes the anode electrode is called an anode electrode, and is disposed on the other side of the ion exchange membrane 50 to pass through hydrogen ions supplied through the ion exchange membrane 50 and the electrode substrate 40' to the catalyst electrode 30 ') The electrode 20 'which causes a reduction reaction to generate water from the oxidizing agent transferred to the electrode 20' is called a cathode electrode.

Meanwhile, the membrane-electrode assembly 100 may further include interfacial bonding layers 10 and 10' positioned between the ion exchange membrane 50 and the catalyst electrodes 30 and 30'.

The interfacial adhesion layers 10 and 10' allow the membrane-electrode assembly 100 to have low hydrogen permeability without reducing the hydrogen ion conductivity, and the catalyst electrodes 30 and 30' and the ion exchange membrane 50 The durability of the membrane-electrode assembly 100 may be improved by improving interfacial bonding between the membrane electrodes, and the performance and durability of the membrane-electrode assembly 100 under high temperature/low humidity conditions may be improved.

In FIG. 3, the interfacial adhesion layers 10 and 10' are shown as disposed on both sides of the ion exchange membrane 50, but the present invention is not limited thereto, and the interfacial adhesion layers 10 and 10' are disposed on both sides of the ion exchange membrane 50. It may be located on only one surface of the exchange membrane 50.

The interfacial adhesive layers 10 and 10' include an ionomer and the radical scavenger.

The ionomer included in the interfacial adhesion layers 10 and 10' improves the interfacial bonding between the catalyst electrodes 30 and 30' and the ion exchange membrane 50, thereby improving durability of the membrane-electrode assembly 100. can make it

The ionomer included in the interfacial adhesive layers 10 and 10' may have an equivalent weight (EW) of 1100 g/eq or less, specifically 500 g/eq to 1100 g/eq. The equivalent weight of the ionomer is the molecular mass of the ionomer per ion exchange group included in the ionomer.

The interfacial adhesive layers 10 and 10' can have a positive effect on water management of the membrane-electrode assembly 100 under low humidity conditions by adjusting the equivalent weight of the ionomer, and when using the ionomer having the equivalent weight. , the performance of the membrane-electrode assembly 100 can be improved without deteriorating the conductivity of hydrogen ions. On the other hand, when the equivalent weight of the ionomer is less than 500 g / eq, the dissolution of the ionomer or the permeability of hydrogen fuel may increase, and when it exceeds 1100 g / eq, the hydrogen ion conductivity may be lowered under high temperature and low humidity conditions.

The ionomer included in the interfacial adhesive layers 10 and 10' may be any one selected from the group consisting of fluorine-based ionomers, hydrocarbon-based ionomers, and mixtures thereof.

The fluorine-based ionomer has a cation exchange group capable of transferring cations such as protons or anion exchange groups capable of transferring anions such as hydroxy ions, carbonates or bicarbonates, and includes fluorine-containing polymers in the main chain; or partially fluorinated polymers such as polystyrene-graft-ethylenetetrafluoroethylene copolymers or polystyrene-graft-polytetrafluoroethylene copolymers, and specific examples include poly(perfluorosulfonic acid), It may be poly(perfluorocarboxylic acid), a copolymer of tetrafluoroethylene containing a sulfonic acid group and fluorovinyl ether, a fluorinated polymer including a defluorinated sulfurized polyether ketone, or a mixture thereof. The cation exchange group may be any one selected from the group consisting of a sulfonic acid group, a carboxyl group, a boronic acid group, a phosphoric acid group, an imide group, a sulfonimide group, a sulfonamide group, and combinations thereof, and may generally be a sulfonic acid group or a carboxyl group. there is. In addition, the above fluorine-based ionomers may be used alone or in combination of two or more.

In addition, the hydrocarbon-based ionomer has a cation exchange group capable of transferring a cation such as a proton, or an anion exchange group capable of transferring an anion such as a hydroxy ion, carbonate or bicarbonate, and imidazole, benzimidazole, Polyamide, polyamideimide, polyimide, polyacetal, polyethylene, polypropylene, acrylic resin, polyester, polysulfone, polyether, polyetherimide, polyester, polyethersulfone, polyetherimide, polycarbonate, polystyrene, It may include a hydrocarbon-based polymer such as polyphenylene sulfide, polyether ether ketone, polyether ketone, polyaryl ether sulfone, polyphosphazene, or polyphenylquinoxaline, and specific examples include sulfonated polyimide. , S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimidazole (SPBI), Sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated polyquinoxaline, alcohol sulfonated polyketone, sulfonated polyphenylene oxide, sulfonated polyether sulfone, sulfonated polyether ketone, sulfonated poly phenylene sulfone (sulfonated polyphenylene sulfone), sulfonated polyphenylene sulfide (sulfonated polyphenylene sulfide), sulfonated polyphenylene sulfide sulfone, sulfonated polyphenylene sulfide sulfone nitrile, sulfonated polyarylene ether, sulfonated polyaryl Hydrocarbons including sulfonated polyarylene ether nitrile, sulfonated polyarylene ether ether nitrile, polyarylene ether sulfone ketone, and mixtures thereof Polymers may be used, but are not limited thereto. In addition, the hydrocarbon-based ionomers may be used alone or in combination of two or more.

Meanwhile, the membrane-electrode assembly 100 is formed within the catalytic electrodes 30 and 30', within the ion exchange membrane 50, between the ion exchange membrane 50 and the catalytic electrodes 30 and 30', and in combinations thereof. It includes the radical scavenger at any one position selected from the group consisting of Specifically, between the ion exchange membrane 50 and the catalyst electrodes 30 and 30 'may mean including the radical scavenger inside the interfacial adhesion layer 10 and 10', or the ion exchange membrane ( 50), the surface of the catalytic electrodes 30 and 30', or the surface of the interfacial adhesive layer 10 and 10'.

In particular, when the radical scavenger is included in the interfacial adhesive layers 10 and 10', the radical scavenger does not exist in a dispersed form inside the ion exchange membrane 50, but the ion exchange membrane 50 and the interfacial adhesion layers 10 and 10' inserted between the catalytic electrodes 30 and 30', thereby minimizing the ion conductivity loss of the ion exchange membrane 50 itself, thereby reducing the chemical properties of the ion exchange membrane 50. durability can be improved. That is, the radicals generated from the catalytic electrodes 30 and 30' diffuse toward the ion exchange membrane 50, but the radical scavengers concentrated in the interfacial adhesion layers 10 and 10' before the ion exchange membrane 50 As a result, deterioration of the ion exchange membrane 50 can be prevented in advance.

In addition, since the deterioration of the ion exchange membrane 50 proceeds from the interface between the ion exchange membrane 50 and the catalyst electrodes 30 and 30', the radical scavenger is applied to the interface adhesive layer 10 and 10'. By concentrating, more excellent chemical durability can be obtained compared to dispersing the radical scavenger in the ion exchange membrane 50 .

However, when the interfacial adhesive layer (10, 10') includes the radical scavenger, elution of the radical scavenger during operation of the fuel cell may be more problematic, but the radical scavenger is the peroxide or By forming a porous carbon coating layer on the surface of core particles capable of decomposing radicals to stabilize the core particles capable of decomposing the peroxide or radicals, elution of the core particles capable of decomposing the peroxide or radicals can be prevented.

The interfacial adhesive layer (10, 10') may include the radical scavenger in an amount of 0.1 wt% to 70 wt%, and in an amount of 5 wt% to 15 wt%, based on the total weight of the interfacial adhesive layer (10, 10'). can include When the content of the radical scavenger is less than 0.1% by weight, the effect of improving chemical durability may be insignificant, and when the content of the radical scavenger exceeds 70% by weight, ion transfer resistance within the membrane-electrode assembly 100 may be greatly increased.

In addition, the interfacial adhesive layer (10, 10 ') may have a thickness of 10 nm to 10 µm and 0.5 µm to 2 µm, and a loading amount of the interfacial adhesive layer (10, 10') may be 0.01 mg/cm ² to 2.0 mg/cm ² . When the thickness of the interfacial adhesive layers 10 and 10' is less than 10 nm or the loading amount is less than 0.01 mg/cm ² , the effect of improving chemical durability may be insignificant, and the ion exchange membrane 50 and the catalyst electrodes 30 and 30' Interfacial bonding between membrane electrodes may not be improved, and ion transfer resistance in the membrane-electrode assembly 100 may be greatly increased when the thickness exceeds 10 μm or the loading amount exceeds 2.0 mg/cm ² .

Meanwhile, the ion exchange membrane 50 includes an ion conductor. The ion conductor may be a cation conductor having a cation exchange group capable of transferring cations such as protons, or an anion conductor having an anion exchange group capable of transferring anions such as hydroxy ions, carbonates or bicarbonates.

The cation exchange group may be any one selected from the group consisting of a sulfonic acid group, a carboxyl group, a boronic acid group, a phosphoric acid group, an imide group, a sulfonimide group, a sulfonamide group, and combinations thereof, and may generally be a sulfonic acid group or a carboxyl group. there is.

The cation conductor may include a fluorine-based polymer including the cation exchange group and including fluorine in a main chain; Benzimidazole, polyamide, polyamideimide, polyimide, polyacetal, polyethylene, polypropylene, acrylic resin, polyester, polysulfone, polyether, polyetherimide, polyester, polyethersulfone, polyetherimide, poly hydrocarbon-based polymers such as carbonate, polystyrene, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyaryl ether sulfone, polyphosphazene or polyphenylquinoxaline; partially fluorinated polymers such as polystyrene-graft-ethylenetetrafluoroethylene copolymers or polystyrene-graft-polytetrafluoroethylene copolymers; A sulfone imide etc. are mentioned.

More specifically, when the cation conductor is a hydrogen ion cation conductor, the polymers may include a cation exchange group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in their side chains. Specific examples include poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, defluorinated sulfurized polyether ketone, or mixtures thereof. Fluorine-based polymer containing; Sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimide sulfonated polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated poly sulfonated polyquinoxaline, sulfonated polyketone, sulfonated polyphenylene oxide, sulfonated polyether sulfone, sulfonated polyether ketone polyether ketone), sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, sulfonated polyphenylene sulfonated polyphenylene sulfide sulfone nitrile, sulfonated polyarylene ether, sulfonated polyarylene ether nitrile, sulfonated polyarylene ether ether nitrile ( sulfonated polyarylene ether ether nitrile), polyarylene ether sulfone ketone (sulfonated polyarylene ether sulfone ketone), and their Hydrocarbon-based polymers including mixtures may be used, but are not limited thereto.

On the other hand, among the cationic conductors, hydrocarbon-based ion conductors having excellent ion conduction function and being advantageous in price can be preferably used.

The anion conductor is a polymer capable of transporting anions such as hydroxy ion, carbonate or bicarbonate, and the anion conductor is commercially available in the form of a hydroxide or halide (usually chloride), and the anion conductor is an industrial constant (water purification), metal separation or catalytic processes.

Generally, metal hydroxide-doped polymers may be used as the anion conductor, and specifically, metal hydroxide-doped poly(ethersulfone), polystyrene, vinyl-based polymers, poly(vinyl chloride), and poly(vinylidene fluoride) , poly(tetrafluoroethylene), poly(benzimidazole), or poly(ethylene glycol) may be used.

On the other hand, the ion exchange membrane 50 may be in the form of a reinforced membrane in which the ion conductor fills the pores of a fluorine-based porous support such as e-PTFE or a porous nanoweb support prepared by electrospinning.

The ion exchange membrane 50 may have an ion exchange capacity (IEC) of 0.8 to 4.0 meq/g or 1.0 to 3.5 meq/g. When the ion exchange capacity of the ion exchange membrane 50 is less than 1.0 meq/g, the movement of hydrogen ions can be reduced under low humidification conditions, and when it exceeds 3.5 meq/g, the transfer resistance at the interface increases as the humidification rate increases. can increase

In addition, the ion exchange membrane 50 may have a thickness of 3 to 25 μm or 5 to 20 μm. When the thickness of the ion exchange membrane 50 is less than 3 μm, the permeability of the hydrogen fuel is rapidly increased under high temperature and low humidity conditions, and thus the chemical stability of the ion exchange membrane may be deteriorated. When the thickness exceeds 25 μm, hydrogen ions under low humidity conditions The movement of is decreased, and the resistance of the ion exchange membrane is increased, so that the ion conductivity may be reduced.

As the core particles of the catalytic electrodes 30 and 30', any material that can be used as a catalyst for hydrogen oxidation and oxygen reduction reactions may be used, and a platinum-based metal may be preferably used.

The platinum-based metal is platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), a platinum-M alloy (wherein M is palladium (Pd), ruthenium (Ru), iridium ( Ir), Osmium (Os), Gallium (Ga), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper ( Any one selected from the group consisting of Cu), silver (Ag), gold (Au), zinc (Zn), tin (Sn), molybdenum (Mo), tungsten (W), lanthanum (La) and rhodium (Rh) or above), may include one selected from the group consisting of non-platinum alloys and combinations thereof, and more preferably, a combination of two or more metals selected from the platinum-based catalyst metal group may be used, but limited thereto It is not, and any platinum-based catalytic metal usable in the art may be used without limitation.

Specifically, the platinum alloy is Pt-Pd, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ru, Pt-Ru-W, Pt-Ru-Mo, Pt-Ru-Rh-Ni, Pt-Ru-Sn-W, Pt-Co, Pt-Co-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-Co-S, Pt-Co-P, Pt-Fe, Pt-Fe- Ir, Pt-Fe-S, Pt-Fe-P, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Ni, Pt-Ni-Ir, Pt-Cr, Pt-Cr- It may be used alone or in combination of two or more selected from the group consisting of Ir and combinations thereof.

In addition, the non-platinum alloy is Ir-Fe, Ir-Ru, Ir-Os, Co-Fe, Co-Ru, Co-Os, Rh-Fe, Rh-Ru, Rh-Os, Ir-Ru-Fe, Ir - It may be used alone or in combination of two or more selected from the group consisting of Ru-Os, Rh-Ru-Fe, Rh-Ru-Os, and combinations thereof.

In addition, the core particle may be a metal itself (black), or may be used by supporting a catalyst metal on a carrier.

The carrier may be selected from carbon-based carriers, porous inorganic oxides such as zirconia, alumina, titania, silica, and ceria, and zeolites. The carbon-based carrier is graphite, super P, carbon fiber, carbon sheet, carbon black, Ketjen Black, Denka black, acetylene Acetylene black, carbon nano tube (CNT), carbon sphere, carbon ribbon, fullerene, activated carbon, carbon nano fiber, carbon nano wire, carbon nano ball , carbon nanohorn, carbon nanocage, carbon nanoring, ordered nano-/meso-porous carbon, carbon airgel, mesoporous carbon, graphene, stabilized carbon, activated carbon, and It may be selected from one or more combinations thereof, but is not limited thereto, and carriers usable in the art may be used without limitation.

The core particles may be located on the surface of the carrier, or may penetrate into the carrier while filling internal pores of the carrier.

In the case of using the noble metal supported on the carrier as a catalyst, a commercially available catalyst may be used, or it may be prepared and used by supporting a noble metal on the carrier. Since the process of supporting the noble metal on the support is widely known in the art, detailed descriptions thereof are omitted in this specification, but can be easily understood by those skilled in the art.

The core particles may be contained in an amount of 20% to 80% by weight based on the total weight of the catalytic electrodes 30 and 30'. %, the active area may be reduced due to the aggregation of the core particles, and thus the catalytic activity may be lowered.

In addition, the catalytic electrodes 30 and 30' may include a binder to improve adhesion of the catalytic electrodes 30 and 30' and transfer hydrogen ions. It is preferable to use an ionomer having ion conductivity as the binder, and since the description of the ionomer is the same as that of the interfacial adhesive layers 10 and 10', a repetitive description will be omitted.

However, the ionomer may be used in the form of a single substance or a mixture, and may also be selectively used together with a non-conductive compound for the purpose of further improving adhesion to the ion exchange membrane 50. It is preferable to adjust the amount used to suit the purpose of use.

Examples of the non-conductive compound include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), and ethylene/tetrafluoroethylene. Roethylene (ethylene/tetrafluoroethylene (ETFE)), ethylene chlorotrifluoro-ethylene copolymer (ECTFE), polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), dodecane At least one selected from the group consisting of sylbenzenesulfonic acid and sorbitol may be used.

The binder may be included in an amount of 20% to 80% by weight based on the total weight of the catalyst electrodes 30 and 30'. If the content of the binder is less than 20% by weight, generated ions may not be well transmitted, and if it exceeds 80% by weight, it is difficult to supply hydrogen or oxygen (air) due to lack of pores and an active area that can react. this may decrease

In addition, the membrane-electrode assembly 100 may further include electrode substrates 40 and 40' outside the catalyst electrodes 30 and 30'.

A porous conductive substrate may be used as the electrode substrate 40 or 40' so that hydrogen or oxygen can be smoothly supplied. Representative examples thereof include carbon paper, carbon cloth, carbon felt, or metal cloth (a porous film composed of fibrous metal cloth or a metal film formed on the surface of a cloth formed of polymer fibers). refers to) can be used, but is not limited thereto. In addition, it is preferable to use a water-repellent material treated with a fluorine-based resin as the electrode substrates 40 and 40' because it can prevent the reactant diffusion efficiency from being lowered due to water generated during operation of the fuel cell. Examples of the fluorine-based resin include polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkylvinyl ether, polyperfluorosulfonylfluoride alkoxyvinyl ether, fluorinated ethylene propylene ( Fluorinated ethylene propylene), polychlorotrifluoroethylene, or copolymers thereof may be used.

In addition, a microporous layer for enhancing the diffusion effect of the reactants in the electrode substrates 40 and 40' may be further included. This microporous layer is generally made of conductive powder having a small particle size, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotube, carbon nanowire, or carbon nanohorn. -horn) or a carbon nano ring.

The microporous layer is prepared by coating the electrode substrates 40 and 40' with a composition including a conductive powder, a binder resin, and a solvent. Examples of the binder resin include polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkylvinyl ether, polyperfluorosulfonylfluoride, alkoxyvinyl ether, polyvinyl alcohol, and cellulose acetate. or copolymers thereof and the like may be preferably used. Alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, and butyl alcohol, water, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, tetrahydrofuran, and the like may be preferably used as the solvent. The coating process may be a screen printing method, a spray coating method, or a coating method using a doctor blade depending on the viscosity of the composition, but is not limited thereto.

The membrane-electrode assembly 100 including the radical scavenger may be manufactured by adding the radical scavenger when manufacturing each component of the membrane-electrode assembly 100 according to the location where the radical scavenger is included. can

For example, when the radical scavenger is included in the ion exchange membrane 50, the radical scavenger is added to the composition for forming an ion exchange membrane including the ion conductor, and then the radical scavenger is included. A single membrane may be prepared by applying and drying the composition for forming an ion exchange membrane, or the ion exchange membrane 50 in the form of a reinforced membrane may be prepared by impregnating a porous support with the composition for forming an ion exchange membrane including the radical scavenger. there is.

Similarly, when the radical scavenger is included in the catalytic electrodes 30 and 30', the catalytic electrode including the radical scavenger is formed after adding the radical scavenger to the composition for forming the catalytic electrode. The catalytic electrodes 30 and 30' including the radical scavenger may be prepared by applying and drying the composition.

In addition, when the radical scavenger is included between the ion exchange membrane 50 and the catalyst electrodes 30 and 30', a solution containing the radical scavenger is applied to the surface of the ion exchange membrane 50 or the catalyst electrode ( 30, 30 ') may be applied to the surface and dried to form a coating layer.

In addition, the radical scavenger may be included in the interfacial bonding layer 10 or 10'. Hereinafter, a case in which the interfacial bonding layer 10 or 10' includes the radical scavenger is taken as an example, and the membrane-electrode A method of manufacturing the assembly 100 will be described in detail.

The interfacial adhesion layer (10, 10') including the radical scavenger is prepared by mixing the radical scavenger and the ionomer to form a composition for forming an interfacial adhesion layer, and mixing the composition for forming an interfacial adhesion layer with the ion exchange membrane ( 50) or coating the surface of the catalytic electrodes 30 and 30' and then drying.

The composition for forming the interfacial adhesive layer may be prepared by adding the radical scavenger and the ionomer to a solvent and then mixing them.

The composition for forming the interfacial adhesive layer may include the ionomer at a concentration of 0.1% to 30%, and may include the ionomer at a concentration of 1% to 10%. In the context of the present invention, the concentration means a percent concentration, and the percent concentration can be obtained as a percentage of the mass of the solute relative to the mass of the solution. When the composition for forming the interfacial adhesive layer includes the ionomer in the above concentration range, hydrogen ion conductivity and interfacial junction properties may be improved without increasing the interfacial resistance of the membrane-electrode assembly. When the concentration of the ionomer is less than 0.1%, hydrogen ion transfer ability may be reduced, and when the concentration exceeds 30%, the ionomer distribution may be non-uniform.

Examples of the solvent include alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol, and glycerol, water, dimethylacetamide, dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, and the like. It may be any one selected from the group consisting of mixtures.

The interfacial adhesion layers 10 and 10' may be formed by applying the composition for forming the interfacial adhesion layer onto the ion exchange membrane 50 or the catalyst electrodes 30 and 30' and then drying the composition. As a method of applying the composition for forming the interfacial adhesive layer on the ion exchange membrane 50, slot die coating, bar coating, dip coating, comma coating, screen printing, spray coating, doctor blade coating, silk screen coating, gravure coating, A painting method or the like can be used.

The drying process may be drying at 25 ℃ to 90 ℃ for 12 hours or more. If the drying temperature is less than 25 ° C. and the drying time is less than 12 hours, it may not be possible to form a sufficiently dried interfacial adhesive layer (10, 10 ′), and when dried at a temperature exceeding 90 ° C., the interfacial adhesive layer ( 10 , 10 ′) ) may crack.

Finally, the membrane-electrode assembly 100 is manufactured using the ion exchange membrane 50 including the interfacial adhesive layers 10 and 10' or the catalyst electrodes 30 and 30'.

When the interfacial adhesion layers 10 and 10' are formed on the catalyst electrodes 30 and 30', the ion exchange membrane 50 and the catalyst electrodes 30 and 30' are thermally compressed to form the membrane-electrode assembly ( 100) can be manufactured, and when the interfacial adhesion layers 10 and 10' are formed on the ion exchange membrane 50, the ion exchange membrane 50 and the catalyst electrodes 30 and 30' are thermally compressed, The membrane-electrode assembly 100 may be manufactured by coating the ion exchange membrane 50 with the catalyst electrodes 30 and 30'.

Thermal compression of the catalytic electrodes 30 and 30' and the ion exchange membrane 50 may be performed under conditions of 80 °C to 2000 °C and 5 kgf/cm ² to 200 kgf/cm ² . When thermal compression is performed under conditions of 80 °C and less than 50 kgf/cm ² , transfer of the catalytic electrodes 30 and 30' on the release film may not be performed properly, and when the temperature exceeds 200 °C, the ion exchange membrane There is a possibility that the polymer of (50) may be denatured, and under conditions exceeding 200 kgf/cm ² , collapse of the pore structure in the catalyst electrodes 30 and 30' may cause performance degradation.

A fuel cell according to another embodiment of the present invention includes the membrane-electrode assembly.

4 is a schematic diagram showing the overall configuration of the fuel cell.

Referring to FIG. 4 , the fuel cell 200 includes a fuel supply unit 210 that supplies mixed fuel in which fuel and water are mixed, and a reforming unit that reforms the mixed fuel to generate reformed gas containing hydrogen gas ( 220), a stack 230 in which a reformed gas containing hydrogen gas supplied from the reforming unit 220 reacts electrochemically with an oxidizing agent to generate electrical energy, and the oxidizing agent is transferred between the reforming unit 220 and the stack It includes an oxidizing agent supply unit 240 supplying to 230.

The stack 230 includes a plurality of unit cells generating electrical energy by inducing an oxidation/reduction reaction between a reformed gas including hydrogen supplied from the reforming unit 220 and an oxidizing agent supplied from the oxidizing agent supplying unit 240. provide

Each unit cell means a unit cell that generates electricity, and includes the membrane-electrode assembly for oxidizing/reducing oxygen in the reformed gas containing hydrogen gas and the oxidizing agent, and the reforming gas containing hydrogen gas and the oxidizing agent. and a separator plate (also referred to as a bipolar plate, hereinafter referred to as a 'separator plate') for supplying to the membrane-electrode assembly. The separators are disposed on both sides of the membrane-electrode assembly with the membrane-electrode assembly at the center. At this time, the separators respectively located at the outermost side of the stack are also referred to as end plates.

Among the separators, the end plate includes a pipe-shaped first supply pipe 231 for injecting reformed gas including hydrogen gas supplied from the reforming unit 220 and a pipe-shaped second pipe-shaped pipe for injecting oxygen gas. A supply pipe 232 is provided, and on the other end plate, a first discharge pipe 233 for discharging reformed gas containing hydrogen gas that is finally unreacted and remaining in a plurality of unit cells to the outside, and the unit cell described above. Finally, a second discharge pipe 234 is provided for discharging the unreacted and remaining oxidizing agent to the outside.

Hereinafter, specific embodiments of the present invention are presented. However, the embodiments described below are only intended to specifically illustrate or explain the present invention, and the present invention is not limited thereto. In addition, the content not described herein can be sufficiently technically inferred by those skilled in the art, and the description thereof will be omitted.

Preparation Example 1: Preparation of porous cerium particles

After dissolving 1.0 g of Ce(NO ₃ ) ₃ 6H ₂ O in 1 mL of double distilled water (DD water), 2.0 g of adipic acid and 30 mL of ethylene glycol were added to the distilled water, Sonication was performed to form a cerium dispersion. The cerium dispersion was placed in an autoclave and heated at 180 °C for 5 hours. After the completion of the reaction, the cerium dispersion was air-cooled to room temperature, centrifuged, washed several times with double distilled water and ethanol, and vacuum dried at 40 °C to prepare porous cerium oxide (CeO ₂ ) particles.

Preparation Example 2: Preparation of radical scavenger (1)

A polymer dispersion was prepared by adding 20 g of Nafion (Nafion ^™ , DuPont) as a fluorine-based polymer to 80 mL of a mixed solvent of normal propyl alcohol (n-propanol) and water. 10 g of porous cerium oxide particles prepared in Preparation Example 1 were added to the polymer dispersion and mixed uniformly. The resonance mixer was operated at 5 to 50% power and 3 cycles (10 minutes of operation followed by 5 minutes of interruption -> 1 cycle).

Thereafter, a powder-type radical scavenger was obtained by spraying a dispersion of a mixture of a fluorine-based polymer and cerium oxide particles at a temperature of 50 to 80 °C. Next, after ball milling the radical scavenger at 200 to 500 rpm, it was put into an oven under a nitrogen atmosphere, and heat treatment was performed at 180° C. for 5 minutes.

The radical scavenger after the heat treatment was immersed in 0.3 M sulfuric acid aqueous solution for 2 hours, then immersed in 80 ℃ distilled water for 2 hours, and then dried again at 80 ℃ temperature for 8 hours to make the fluorine-based polymer porous. A radical scavenger impregnated between pores of cerium oxide was prepared.

Preparation Example 3: Preparation of radical scavenger (2)

A radical scavenger was prepared in the same manner as in Preparation Example 2 except that non-porous cerium oxide particles were used and the heat treatment conditions were changed. was manufactured

The relative crystallinity of the prepared radical scavenger was measured using XRD, and the XRD analysis pattern is shown in FIG. 5 . A radical scavenger having a relative crystallinity of 10.0 to 12.0% (black graph in FIG. 5, heat treatment temperature 160° C.) and a radical scavenger having a crystallinity of 14.0 to 16.0% (red graph in FIG. 5, heat treatment temperature 220° C.) were prepared. confirmed that it was. Here, the crystallinity range includes a range of errors during manufacturing and errors during XRD analysis.

Example 1: Membrane-electrode assembly including an interfacial adhesion layer containing a radical scavenger (1)

In order to prepare a composition for forming an interfacial adhesive layer, the radical scavenger prepared in Preparation Example 2 and Nafion ^TM ionomer were mixed so that the content of cerium oxide was 4% by weight based on the total content of the composition, and isopropyl alcohol ( IPA) was dispersed. At this time, the content of solids compared to the solvent was adjusted to 10% by weight.

To prepare the ion exchange membrane, 10% by weight of sulfonated polyarylethersulfone (S-PAES) was dissolved in dimethylacetamide (DMAC). The prepared composition for forming an ion exchange membrane was coated on a glass plate using a blade coating method, and then dried in an oven at 60° C. for 24 hours to prepare an ion exchange membrane.

The prepared ion exchange membrane was dip-coated with the composition for forming interfacial adhesion, and the composition for forming interfacial adhesion was coated on the surface of the ion exchange membrane, and dried in an oven at 60° C. for 24 hours. Thereafter, the interfacial adhesive layer was annealed in an oven at 120° C. for 2 hours to prepare a membrane-electrode assembly.

Example 2: Membrane-electrode assembly including an interfacial adhesion layer containing a radical scavenger (2)

A membrane-electrode assembly was prepared in the same manner as in Example 1, except that the radical scavenger prepared in Preparation Example 3, having a crystallinity of 10.0 to 12.0% of the coating layer containing the fluorine-based polymer, was used.

Example 3: Membrane-electrode assembly including an interfacial adhesion layer containing a radical scavenger (3)

A membrane-electrode assembly was prepared in the same manner as in Example 1, except that the radical scavenger prepared in Preparation Example 3, having a crystallinity of 14.0 to 16.0% of the coating layer containing the fluorine-based polymer, was used.

Comparative Example 1: Membrane-electrode assembly including an interfacial adhesive layer containing a radical scavenger (4)

A membrane-electrode assembly was manufactured in the same manner as in Example 1, except that the porous cerium particles prepared in Preparation Example 1 were used instead of the radical scavenger prepared in Preparation Example 2 in Example 1.

[Experimental Example 1] Durability evaluation

Durability evaluation was conducted on the membrane-electrode assembly prepared in Comparative Examples and Examples. Durability evaluation was conducted in accordance with the OCV (Open-circuit voltage) durability evaluation protocol of the US Department of Energy (DOE). OCV holding test conditions according to DOE standards are as follows: 90 ° C, RH 30%, 50 kPa.

The OCV durability results are shown in Table 1 below:

OCV durability
(hour) comparative example about 1000 to 1400 hours Example 1 About 1700 to 2300 hours Example 2 about 1900 to 2500 hours Example 3 about 2000 to 2700 hours

Although the preferred embodiment of the present invention has been described in detail above, the above embodiment is presented as a specific example of the present invention, whereby the present invention is not limited, and the scope of the present invention is covered by the claims to be described later. Various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in , also belong to the scope of the present invention.

1: Particles capable of trapping peroxides or radicals
2: coating layer containing fluorine-based polymer
5: radical scavenger
100: membrane-electrode assembly
10, 10': interfacial adhesive layer
20, 20': electrode
30, 30': catalyst electrode
40, 40': electrode substrate
50: ion exchange membrane
200: fuel cell
210: fuel supply unit 220: reforming unit
230: stack 231: first supply pipe
232: second supply pipe 233: first discharge pipe
234: second discharge pipe 240: oxidant supply unit

Claims (24)

particles capable of trapping peroxides or radicals; and
Containing a fluorine-based polymer introduced to at least a part of the outer surface and the inside of the particle
Radical scavenger. In paragraph 1,
The particles include at least one selected from the group consisting of transition metals, noble metals, ions thereof, salts thereof, oxides thereof, nitrides thereof, and complexes thereof,
Radical scavenger. In paragraph 1,
The fluorine-based polymer is a poly(perfluorosulfonic acid), a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, or a fluorine-based polymer containing a mixture thereof,
Radical scavenger. In paragraph 1,
The particle is a porous particle containing a plurality of pores,
The fluorine-based polymer is impregnated into the pores of the particles,
Radical scavenger. In paragraph 1,
Including a coating layer on the outer surface of the particle,
Wherein the coating layer includes the fluorine-based polymer,
Radical scavenger. In paragraph 5,
The coating layer is formed in an area of 30% to 70% of the total external surface area of the particle,
Radical scavenger. In paragraph 1,
The average particle diameter of the particles is 50 nm to 1 μm,
Radical scavenger. In paragraph 5,
The thickness of the coating layer is 5% to 30% of the average particle diameter range of the particles,
Radical scavenger. In paragraph 5,
The relative degree of crystallinity (RDOC) of the coating layer is 10.0% to 16.0%,
Radical scavenger. In paragraph 1,
The content of the particles is 30 to 80% by weight relative to the total weight of the radical scavenger,
Radical scavenger. preparing particles capable of trapping peroxides or radicals;
introducing a fluorine-based polymer to at least a part of the outer surface and the inside of the particle; and
Including the step of heat-treating the particles into which the fluorine-based polymer is introduced,
Manufacturing method of radical scavenger. In paragraph 11,
The particle is a porous particle formed by a one-pot hydrothermal synthesis method, a sol-gel method, or a cavity formation method by redox,
Manufacturing method of radical scavenger. In paragraph 11,
The fluorine-based polymer is a poly(perfluorosulfonic acid), a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, or a fluorine-based polymer containing a mixture thereof,
Manufacturing method of radical scavenger. In paragraph 11,
In the step of introducing the fluorine-based polymer, mixing the dispersion or melt of the fluorine-based polymer with the particles, and then spraying,
The mixing is performed using at least one selected from the group consisting of a homogeneous mixer, a high-pressure disperser, a ball mill, a powder mixer, ultrasonic mixing, and resonant acoustic mixing,
Manufacturing method of radical scavenger. In paragraph 11,
The heat treatment is performed at 120 ° C to 220 ° C,
Manufacturing method of radical scavenger. In paragraph 11,
Further comprising the step of immersing the particles into which the fluorine-based polymer is introduced after the heat treatment in an acidic aqueous solution,
Manufacturing method of radical scavenger. In paragraph 11,
The particles include at least one selected from the group consisting of transition metals, noble metals, ions thereof, salts thereof, oxides thereof, nitrides thereof, and complexes thereof,
Manufacturing method of radical scavenger. In paragraph 11,
The content of the particles is 30 to 80% by weight relative to the total weight of the radical scavenger,
Manufacturing method of radical scavenger. ion exchange membrane,
Catalyst electrodes disposed on both sides of the ion exchange membrane, and
A membrane-electrode assembly comprising the radical scavenger according to claim 1 at any one position selected from the group consisting of within the catalyst electrode, within the ion exchange membrane, between the ion exchange membrane and the catalyst electrode, and combinations thereof. In paragraph 19,
The membrane-electrode assembly
Further comprising an interfacial adhesion layer positioned between the ion exchange membrane and the catalyst electrode,
The membrane-electrode assembly, wherein the interfacial adhesion layer includes an ionomer and the radical scavenger. In paragraph 20,
The membrane-electrode assembly, wherein the interfacial adhesive layer comprises 0.1 wt% to 70 wt% of the radical scavenger based on the total weight of the interfacial adhesive layer. In paragraph 20,
The thickness of the interfacial adhesive layer is 5 nm to 5 μm, the membrane-electrode assembly. In paragraph 20,
A loading amount of the interfacial adhesive layer is 0.01 mg/cm ² to 2.0 mg/cm ² The membrane-electrode assembly. A fuel cell comprising the membrane-electrode assembly according to claim 19.

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