CN117438594A - Multi-step electrode slurry preparation method for improving additive and ionomer dispersibility in electrode and electrode for polymer electrolyte fuel cell - Google Patents

Multi-step electrode slurry preparation method for improving additive and ionomer dispersibility in electrode and electrode for polymer electrolyte fuel cell Download PDF

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CN117438594A
CN117438594A CN202310246362.8A CN202310246362A CN117438594A CN 117438594 A CN117438594 A CN 117438594A CN 202310246362 A CN202310246362 A CN 202310246362A CN 117438594 A CN117438594 A CN 117438594A
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electrode
dispersion
antioxidant
slurry
ionomer
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李正揆
柳丞镐
杨素英
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Fuxi Miti Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8663—Selection of inactive substances as ingredients for catalytic active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1046—Mixtures of at least one polymer and at least one additive
    • H01M8/1051—Non-ion-conducting additives, e.g. stabilisers, SiO2 or ZrO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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Abstract

Relates to a multi-step electrode slurry preparation method for improving the dispersibility of additives and ionomers in electrodes and electrodes for polymer electrolyte fuel cells. The method comprises the following steps: a first step of mixing an antioxidant and a dispersion solvent; a second step of performing a first dispersion for finely dividing and uniformly dispersing the nano-sized antioxidant particles on the mixture; a third step of mixing the first-dispersed mixture with a fluorine-based ionomer solution; a fourth step of performing a second dispersion such that the antioxidant is present adjacent to the ionomer through interaction of the antioxidant particles with the ionomer; a fifth step of mixing the catalyst mixed with water and the second-dispersed mixture to prepare a slurry; a sixth step of coating the slurry; seventh, the coated slurry is heated and dried to prepare an electrode, the second step improves the deterioration resistance efficiency, the active area of the antioxidant is increased by the physical force through the first dispersion process, and the fourth step improves the degree of freedom of the ionomer polymer on the mixture.

Description

Multi-step electrode slurry preparation method for improving additive and ionomer dispersibility in electrode and electrode for polymer electrolyte fuel cell
Technical Field
The present invention relates to a method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode, and an electrode for a polymer electrolyte fuel cell. More particularly, it relates to a method of preparing an electrode, in which a pretreatment step of an antioxidant and an ionomer is added to increase the dispersibility of the antioxidant in the electrode and exist adjacent to the ionomer in order to increase the anti-deterioration effect of the nanoparticle antioxidant in the electrode.
Background
In general, a Fuel Cell (Fuel Cell) is a power generation technology that generates electric energy by an electrochemical reaction between hydrogen and oxygen, and continuously generates electricity by supplying hydrogen and oxygen to a positive electrode (anode) and a negative electrode (cathode), respectively.
A fuel cell includes a Membrane Electrode Assembly (MEA) having a positive electrode catalyst layer and a negative electrode catalyst layer on both sides of an electrolyte membrane.
Such a catalyst layer may be formed by, after a process of mixing and dispersing a catalyst slurry containing a catalyst and conductive adhesive particles, coating the catalyst slurry on a substrate and transferring to an electrolyte membrane in a dried state.
In order to achieve excellent performance of the membrane electrode assembly, it is important that the catalyst slurry is mixed and dispersed. When the coating step is performed after the dispersion process, the distribution of the catalyst and the pore structure are determined by acting together with the step of transferring the catalyst layer to the electrolyte membrane after that, and thus the path of water generated from the hydrogen ions, electrons, and the anode layer is determined.
Such a path affects the performance of the fuel cell.
In contrast, in the case where the mixing and dispersion state of the catalyst slurry is uneven and the catalyst and the conductive adhesive particles are agglomerated, it is difficult to improve the performance of the fuel cell, and therefore, it is important to solve such a problem in the production process of the membrane electrode assembly and to produce the catalyst slurry maintaining an appropriate mixing and dispersion state.
In order for each additive to function properly in the electrode for a fuel cell, the additive must be present at a target location in the electrode.
In the case where an antioxidant, a reverse voltage inhibitor, and an additive for electrode pore formation and quality improvement are mixed with a structural substance of an electrode at the same time, since each component is not at a desired optimum position but is present at random positions, or each component is not uniformly dispersed, it becomes a resistance factor for degrading performance in a membrane electrode assembly.
Therefore, there is an increasing need for a method of preparing an electrode paste that can solve such a problem.
Prior art literature
Patent literature
Patent document 1:1. korean patent No. 10-1071766 (preparation method and apparatus of catalyst slurry for Fuel cell)
Patent document 2:2. korean patent No. 10-1786674 (mixing/dispersing device of catalyst slurry for fuel cell).
Disclosure of Invention
Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multi-step electrode slurry preparation method and an electrode for a polymer electrolyte fuel cell, which improve dispersibility of additives and ionomers in the electrode.
Specifically, the present invention proposes a method for preparing an electrode, which improves the dispersibility of an antioxidant in an electrode and enables the antioxidant to exist at a position adjacent to an ionomer by adding a pretreatment step of the antioxidant and the ionomer, so as to improve the anti-degradation effect of a nanoparticle antioxidant in the electrode, thereby solving the existing problems.
The electrode for a fuel cell prepared by the method of the present invention can improve the anti-degradation effect while minimizing the content of the antioxidant, and can improve the high current performance of the membrane electrode assembly.
Also, when the process is applied by applying the nano-scale oxide and the metal material other than the nano-particle antioxidant according to the present invention, water generated in the high current region can be easily discharged by securing the air holes in the electrode.
According to the present invention, the antioxidant in the electrode is added for the purpose of preventing the deterioration of the ionomer caused by the radical, and therefore, it is intended to dispose the antioxidant in the vicinity of the ionomer.
And, even though the nanoparticle antioxidant is a nanoscale particle, due to the characteristics of the nanomaterial, it exists in the form of agglomerations of several micrometers or more, and thus it is intended to break up the agglomerated particles into small particles and increase the active area of the antioxidant by applying a strong physical force through a pre-dispersion process.
And, -SO intended to mix the antioxidant first with the ionomer and with the Side chain (Side chain) of the PFSA fluorine-based ionomer 3 The functional groups combine to inhibit reagglomeration of the antioxidant in the slurry.
Further, when weak physical dispersion is performed after mixing of the ionomer, the degree of freedom of the ionomer polymer increases, and electrostatic repulsive force due to charges of functional groups of side chains increases, so that it is intended to improve the performance of the membrane electrode assembly by improving the dispersibility of the catalyst and the ionomer in the slurry.
However, the technical problems to be solved by the present invention are not limited to the above technical problems, and other technical problems not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the following description.
In order to solve the above problems, a multi-step electrode paste preparation method for improving dispersibility of an additive and an ionomer in an electrode according to an example of the present invention includes: a first step of mixing an antioxidant and a dispersion solvent; a second step of performing a first dispersion for finely dividing and uniformly dispersing the nano-sized antioxidant particles on the above mixture; a third step of mixing the first-dispersed mixture with a fluorine-based ionomer solution; a fourth step of performing a second dispersion so that the antioxidant is present in the vicinity of the ionomer by interaction of the antioxidant particles with the ionomer; a fifth step of preparing a slurry by mixing the catalyst mixed with water and the above-mentioned second-dispersed mixture; a sixth step of coating the slurry; and a seventh step of preparing an electrode by heating the coated slurry and drying, wherein the second step may be performed to improve the deterioration resistance efficiency, and the fourth step may be performed to improve the degree of freedom of the ionomer polymer on the mixture by increasing the active area of the antioxidant by the physical force through the first dispersion step.
In the second step, the first dispersion may be performed by at least one of an ultrasonic generator, the ultrasonic probe, a homogenizer (homogenizer), an agitator (Stirrer), and a Magnetic Stirrer (Magnetic Stirrer).
In the fourth step, the second dispersion may be performed by at least one of an ultrasonic generator, the ultrasonic probe, the homogenizer, the stirrer, a magnetic stirrer, and a planetary mixer (planetary mixer).
The stirring speed and the ultrasonic intensity associated with the second dispersion may be lower than those associated with the first dispersion, and the dispersion time associated with the second dispersion may be shorter than those associated with the first dispersion.
And, first, mixing the antioxidant particles and the ionomer in the fourth step, and then preparing a slurry in the fifth step, thereby allowing the slurry to be formed in-SO of the side chain of the PFSA fluorine-based ionomer 3 The functional groups combine while inhibiting reagglomeration of the antioxidant in the slurry.
Further, after mixing the ionomer, the second dispersion may be performed to a degree lower than that of the first dispersion, thereby improving the degree of freedom of the ionomer polymer, increasing electrostatic repulsive force due to charges of functional groups of side chains, improving dispersibility of the catalyst and the ionomer in the slurry, and improving performance of the electrode-based membrane electrode assembly.
And, in the first step, the antioxidant may include cerium oxide (CeO) 2 ) Cerium zirconium oxide (CeZrO) 4 ) Tin dioxide (SnO) 2 ) Titanium dioxide (TiO) 2 ) Manganese dioxide (MnO) 2 ) Manganese carbonate (MnCO) 3 ) The dispersion solvent may include at least one of water, methanol (Ethanol), ethanol (Ethanol), n-propanol (n-propanol), isopropanol (i-propanol), butanol (Butanol), and Ethylene glycol (Ethylene glycol).
In the first step, at least one of a reverse voltage inhibitor and an additive for electrode pore formation and quality improvement may be mixed in addition to the antioxidant.
In order to improve the dispersion of the antioxidant, the particles of the dried antioxidant powder having a predetermined size or larger may be crushed by a mortar and pestle and/or a grinder before the first step, and the particles having a predetermined size or larger may be filtered by a screen (Sieve) to homogenize the size of the antioxidant powder.
In the fifth step, the catalyst mixed with water may be used in order to prevent the catalyst from being ignited when the catalyst contacts the dispersion solvent.
In the fifth step, the slurry may be prepared by at least one of an ultrasonic generator, the ultrasonic probe, a homogenizer, a stirrer, and a magnetic stirrer.
In the sixth step, the slurry may be applied by at least one of a spray Coater (spray), a Bar Coater (Bar Coater), and a Slot Die Coater (Slot Die Coater).
In another aspect, an electrode for a fuel cell prepared by the above-described preparation method may be provided.
In order for each additive to function normally in an electrode for a fuel cell, the additive must be present at a target position in the electrode, but conventionally, when an antioxidant, a reverse voltage inhibitor, and an additive for electrode pore formation and quality improvement are mixed with a structural substance of the electrode at the same time, each component is not present at a desired optimum position but at a random position, or each component is not uniformly dispersed, and therefore, there is a problem that the additive becomes a resistance factor that reduces performance in a membrane electrode assembly.
Accordingly, the present invention can solve the above-mentioned problems by providing a human user with an electrode for a polymer electrolyte fuel cell and a method for producing the electrode.
That is, the present invention can provide a method for preparing an electrode to a user by increasing the dispersibility of an antioxidant in an electrode and allowing the antioxidant to exist at a position adjacent to an ionomer through a pretreatment step of the antioxidant and the ionomer, so as to improve the anti-deterioration effect of a nanoparticle antioxidant in the electrode, thereby solving the existing problems.
The electrode for a fuel cell prepared in this way can improve the anti-deterioration effect while minimizing the content of the antioxidant, and has the effect of improving the high-current performance of the membrane electrode assembly.
Further, when this step is applied by applying a nano-scale oxide and a metal material other than the nano-particle antioxidant, there is an effect that water generated in the high-current region is easily discharged by securing pores in the electrode.
And, even though the nano-particle antioxidant is nano-sized particles, due to the characteristics of nano-materials, it exists in the form of agglomerations of several micrometers or more, and when strong physical force is applied through a pre-dispersion process, the agglomerated particles may be broken into small particles and increase the active area of the antioxidant.
And, when the antioxidant is first mixed with the ionomer, -SO, which may be pendant from the PFSA fluorine-based ionomer 3 The functional groups combine while inhibiting reagglomeration of the antioxidant in the slurry.
In addition, when the weak ultrasonic dispersion is performed after the mixing of the ionomer, the degree of freedom of the ionomer polymer increases, and electrostatic repulsive force due to the charge of the functional group of the side chain increases, so that the performance of the membrane electrode assembly can be improved by improving the dispersibility of the catalyst and the ionomer in the slurry.
On the other hand, the effects that can be obtained from the present invention are not limited to the above-described effects, and other effects not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the following description.
Drawings
Fig. 1 is a flow chart illustrating a multi-step electrode slurry preparation method of the present invention for improving the dispersibility of additives and ionomers in an electrode.
Fig. 2 and 3 are diagrams for explaining steps further performed on the basis of the method of fig. 1.
Fig. 4 shows a schematic diagram of the change in the position of a substance in an electrode according to the electrode slurry preparation method of the present invention.
Fig. 5 shows a particle size analysis (Particle Size Analysis, PSA) of a Slurry (Slurry) prepared by the multi-step dispersion procedure of the present invention.
Fig. 6 shows the performance improvement of a Single Cell (Single Cell) by the multi-step dispersion process of the present invention.
Fig. 7 shows voltage changes before and after the Acceleration Stress Test (AST) performed by the Holding open circuit voltage (OCV Holding) of the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice the present invention. However, the description of the present invention is merely an embodiment for illustrating the structure and function, and thus, the scope of the claims of the present invention should not be construed as being limited to the embodiments described herein. That is, since the embodiments can be variously changed and have various forms, it is to be understood that the scope of the claims of the present invention includes equivalents in which technical ideas can be implemented. Also, the objects or effects set forth in the present invention do not mean that a specific embodiment should include all of the objects or effects or include only those effects, and thus the scope of the claims of the present invention should not be construed as being limited thereto.
The meaning of the terms described in the present invention should be understood as follows.
The terms "first," "second," and the like are used for distinguishing one structural element from another and are not intended to limit the scope of the claims. For example, a first structural element may be named a second structural element, and similarly, a second structural element may also be named a first structural element. When a certain component is referred to as being "connected" to another component, it is understood that the component may be directly connected to the other component or may be interposed therebetween. Conversely, when a reference is made to a certain structural element being "directly connected" to another structural element, it is to be understood that no other structural element is present in the middle. On the other hand, other expressions describing the relation between the structural elements, that is, "between" and "between" or "adjacent to" and "directly adjacent to" and the like, shall be interpreted in the same sense.
It will be understood that, unless the context clearly indicates otherwise, the singular forms may include the plural forms, and the terms "comprises" or "comprising" are to be construed as specifying the presence of the stated features, numbers, steps, actions, structural elements, components or combinations thereof, without precluding the presence or addition of more than one other features or numbers, steps, actions, structural elements, components or combinations thereof.
Unless defined otherwise, terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. Terms having the same definition as in a dictionary generally used should be construed as having the same meaning as in the context of the related art and should not be interpreted as having an idealized or overly formal sense unless expressly so defined herein.
Multi-step electrode slurry preparation method for improving dispersibility of additives and ionomers in electrodes
Fig. 1 is a flow chart illustrating a multi-step electrode slurry preparation method of the present invention for improving the dispersibility of additives and ionomers in an electrode.
Referring to fig. 1, first, step S10 is performed to mix an antioxidant and a dispersion solvent.
In step S10, the dispersion solvent may include at least one of cerium oxide, cerium zirconium oxide, tin dioxide, titanium dioxide, manganese carbonate, and manganese dioxide.
In step S10, the dispersion solvent may include at least one of water, methanol, ethanol, n-propanol, isopropanol, butanol, and ethylene glycol.
In step S10, at least one of a reverse voltage inhibitor and an additive for electrode pore formation and quality improvement may be mixed in addition to the antioxidant.
After that, step S20 is performed to perform a first dispersion for finely dividing and uniformly dispersing the nano-sized antioxidant particles on the mixture.
Step S20 is performed to increase the deterioration resistance efficiency and increase the active area of the antioxidant by the physical force through the first dispersion step.
In step S20, the first dispersion may be performed by at least one of an ultrasonic generator, an ultrasonic probe, a homogenizer, a stirrer, and a magnetic stirrer.
Then, step S30 is performed to mix the first-dispersed mixture with the fluorine-based ionomer solution.
And, step S4 is performed to perform a second dispersion such that the antioxidant is present in a location adjacent to the ionomer through interaction of the antioxidant particles with the ionomer.
Step S40 is performed to increase the degree of freedom of the ionomer polymer on the mixture.
In step S40, the second dispersion may be performed by at least one of an ultrasonic generator, the ultrasonic probe, the homogenizer, the stirrer, a planetary stirrer, and a magnetic stirrer.
The stirring speed and the ultrasonic intensity associated with the second dispersion may be lower than those associated with the first dispersion, and the dispersion time associated with the second dispersion may be shorter than those associated with the first dispersion.
As described above, after mixing the ionomer, the second dispersion may be performed to a degree lower than that of the first dispersion, thereby improving the degree of freedom of the ionomer polymer, increasing electrostatic repulsive force due to charges of the functional groups of the side chains, improving the dispersibility of the catalyst and the ionomer in the slurry, and thus improving the performance of the electrode-based membrane electrode assembly.
And, step S50 is performed to prepare a slurry by mixing the catalyst mixed with water and the above-described second-dispersed mixture.
First, the antioxidant particles and the ionomer are mixed through step S40, and then a slurry is prepared in step S50, SO that-SO at the side chain with PFSA fluorine-based ionomer can be obtained 3 The functional groups combine while inhibiting reagglomeration of the antioxidant in the slurry.
In step S50, the preparation of the slurry may be performed by at least one of an ultrasonic generator, the ultrasonic probe, a homogenizer, a stirrer, and a magnetic stirrer.
Then, step S60 and step S70 are performed, and in step S60, the slurry is applied, and in step S70, the applied slurry is heated and dried, thereby preparing an electrode.
In step S60, the coating of the slurry may be performed by at least one of a spray coater, a bar coater, and a slot die coater.
On the other hand, fig. 2 and 3 are diagrams for explaining steps further performed on the basis of the method of fig. 1.
Referring to fig. 2, in order to improve the dispersion of the antioxidant, a step S5 of pulverizing the dried antioxidant powder to a predetermined size or more by a mortar and pestle and/or a grinder, and filtering the particles of the predetermined size or more by a mesh screen to homogenize the size of the antioxidant powder may be added before the step S10.
Also, referring to fig. 3, before step S50, step S100 may be additionally performed to mix water and the catalyst in order to prevent the catalyst from being ignited when it comes into contact with the dispersion solvent.
Step S100 is performed independently of each of steps S10 to S40.
The method comprises the following steps:
step S10: mixing antioxidant with dispersing solvent
-an antioxidant: ceria, zirconia cerium, tin dioxide, titania, manganese carbonate, manganese dioxide and the like
Additives which can be used in addition to antioxidants as reverse voltage inhibitors (reverse voltage inhibitors, electrode quality improvers, performance improvers, etc.)
To enhance the dispersion of the antioxidant, the dried powder may be crushed into large particles by a pestle/mortar, mill or the like, and filtered through a screen to homogenize the powder size prior to mixing with the solvent
-dispersing solvent: using water, alcohols (methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, etc.) as single solvent or mixed solvent
Step S20: first dispersion
-the purpose is: improving anti-degradation efficiency by finely dividing and uniformly dispersing nanoscale antioxidant particles
-a dispersing device: ultrasonic generator, ultrasonic probe, homogenizer, high-pressure homogenizer, high-speed stirrer, and magnetic stirrer
Step S30: mixed fluorine-based ionomer solution
Step S40: second dispersion
-the purpose is: increasing the degree of freedom of the ionomer polymer such that the antioxidant is present adjacent to the ionomer by the interaction of the antioxidant particles with the ionomer
-a dispersing device: ultrasonic generator, ultrasonic probe, homogenizer, high-pressure homogenizer, high-speed stirrer, planetary stirrer, and magnetic stirrer
The dispersion intensity of the second dispersion is lower than that of the first dispersion (stirring speed or ultrasonic intensity or dispersion time)
Additional independent step S100: mixed catalyst+Water
Because the catalyst is ignited when contacted with an alcoholic solvent, the catalyst is wetted with water to prevent this
Step S50: preparation of slurry by mixing the solution of the second dispersion into the catalyst in step S100
-slurry mixing method: ultrasonic generator, ultrasonic probe, homogenizer, high-pressure homogenizer, and high-speed stirrer
Step S60: slurry coating method for preparing electrode
-spray coater, bar coater, slot die coater
Step S70: preparation of electrodes
-preparing an electrode by drying by heating the coated slurry
Experimental results
Fig. 4 shows a schematic diagram of the change of the position of a substance in an electrode according to the electrode slurry preparation method.
Part (a) of fig. 4 shows an electrode prepared by an existing mixing process, and part (b) shows an electrode prepared by an ultrasonic pretreatment process by adding an antioxidant, ionomer solution according to the present invention.
Further, 10 represents a nanoparticle antioxidant, 20 represents a Pt/C catalyst, and 30 represents a PFSA fluorine-based ionomer.
Referring to fig. 4 (a), in the case of the conventional method, it was confirmed that the degree of dispersion of the ionomer 30, the catalyst 20, and the antioxidant 10 was very low, and the antioxidant 10 was agglomerated and present at random positions.
In contrast, referring to part (b) of fig. 4 of the present invention, it can be confirmed that the degree of freedom of the polymer of the ionomer 30 is high, and thus more flexible, the antioxidant 10 is dispersed and exists in a small size at a position adjacent to the ionomer 30.
Further, it was confirmed that the degree of dispersion of the catalyst 20 increased with the dispersion of the ionomer 30.
The particle dispersion degree of the electrode prepared by the multi-step dispersion process and the performance of the Single Cell (Single Cell) are described based on fig. 5 and 6,
fig. 5 shows particle size analysis (Particle Size Analysis, PSA) of the slurries prepared by the multi-step dispersion procedure of the present invention.
Part (b) of fig. 5 shows the dimensions and percentiles of Ref and the multi-step dispersion process.
Fig. 5 (a) shows the results of particle size analysis of the slurry in Ref and the multi-step dispersing process.
As a result, as shown in part (a) of fig. 5, it was confirmed that the particle size of the slurry was reduced (D50 and D90 were reduced).
Fig. 6 shows that the performance of the single cell is improved by the multi-step dispersion process of the present invention.
Referring to fig. 6, comparing Ref with the multi-step dispersion process, it was confirmed that the multi-step dispersion process improved the performance of the membrane electrode assembly.
That is, it is clear that a high current is generated at the same voltage.
The results of the accelerated stress test of the electrode prepared by the multi-step dispersion process are illustrated by fig. 7.
Fig. 7 shows voltage changes before and after the acceleration stress test with the open circuit voltage maintained.
Referring to fig. 7, the change in the battery electrode before and after the evaluation of the acceleration stress test is shown.
This is a method for evaluating the chemical stability and index (MEA Chemical Stability and Metrics) of a membrane electrode assembly in the proton exchange membrane fuel cell test protocol (DOE's PEM Fuel Cell Testing Protocol) of the U.S. department of energy, and is a method for evaluating the ionomer degradation of an electrolyte membrane and an electrode.
The results of fig. 7 were performed under the following conditions:
-battery temperature: 90 DEG C
-relative humidity: 30% of negative electrode and 30% of positive electrode
-evaluation conditions: maintaining open circuit voltage
Evaluation time: 500 hours
Fig. 7 shows the battery voltage change before and after 500 hours under the above conditions.
Referring to fig. 7, it was clearly confirmed that the ionomer was less degraded (-18.6% vs-6.51%) when comparing Ref to the multi-step dispersion procedure of the present invention.
Effects of the invention
In order for each additive to function normally in an electrode for a fuel cell, the additive must be present at a target position in the electrode, but conventionally, when an antioxidant, a reverse voltage inhibitor, and an additive for electrode pore formation and quality improvement are mixed with a structural substance of the electrode at the same time, since each component is not present at a desired optimum position but at a random position, or each component is not uniformly dispersed, there is a problem that the additive becomes a resistance factor that adversely reduces performance in a membrane electrode assembly.
The present invention can solve the above-mentioned problems by providing the above-mentioned electrode for a polymer electrolyte fuel cell and a method for producing the electrode to a user.
That is, the present invention can provide a method for preparing an electrode to a user by increasing the dispersibility of an antioxidant in an electrode and allowing the antioxidant to exist at a position adjacent to an ionomer through a pretreatment step of the antioxidant and the ionomer, so as to improve the anti-deterioration effect of a nanoparticle antioxidant in the electrode, thereby solving the existing problems.
The electrode for a fuel cell prepared in this way can improve the anti-deterioration effect while minimizing the content of the antioxidant, and has the effect of improving the high-current performance of the membrane electrode assembly.
Further, when this step is applied by applying a nano-scale oxide and a metal material other than the nano-particle antioxidant, there is an effect that water generated in the high-current region is easily discharged by securing pores in the electrode.
And, even though the nano-particle antioxidant is nano-sized particles, due to the characteristics of nano-materials, it exists in the form of agglomeration to several micrometers or more, and when strong physical force is applied through a pre-dispersion process, the agglomerated particles may be broken into small particles and increase the active area of the antioxidant.
And, when the antioxidant is first mixed with the ionomer, -SO, which may be pendant from the PFSA fluorine-based ionomer 3 Functional group bonding while inhibiting antioxidant in slurryIs not limited to the agglomeration.
In addition, when weak physical dispersion is performed after mixing of the ionomer, the degree of freedom of the ionomer polymer increases, and electrostatic repulsive force due to charges of functional groups of side chains increases, so that the performance of the membrane electrode assembly can be improved by improving the dispersibility of the catalyst and the ionomer in the slurry.
On the other hand, the effects that can be obtained from the present invention are not limited to the above-described effects, and other effects not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the following description.
Also, the system and the control method thereof as described above are not limited to the structure and method of the above-described embodiments, but various modifications can be made to the above-described embodiments by selectively combining all or part of the embodiments.

Claims (9)

1. A method for preparing a multi-step electrode slurry for improving the dispersion of additives and ionomers in an electrode, comprising:
a first step of mixing an antioxidant and a dispersion solvent;
a second step of performing a first dispersion for finely dividing and uniformly dispersing the nano-sized antioxidant particles on the mixture;
a third step of mixing the first-dispersed mixture with a fluorine-based ionomer solution;
a fourth step of performing a second dispersion such that the antioxidant is present adjacent to the ionomer by interaction of the antioxidant particles with the ionomer;
a fifth step of preparing a slurry by mixing a catalyst mixed with water and the second-dispersed mixture;
a sixth step of coating the slurry; and
a seventh step of drying by heating the coated slurry, thereby preparing an electrode,
the second step is performed to improve the deterioration resistance efficiency, and the active area of the antioxidant is increased by the physical force through the first dispersion process,
the fourth step is performed to increase the degree of freedom of the ionomer polymer on the mixture,
the stirring speed and the ultrasonic intensity associated with the second dispersion are lower than those associated with the first dispersion,
the dispersion time associated with the second dispersion is shorter than the dispersion time associated with the first dispersion,
firstly, mixing the antioxidant particles and the ionomer through the fourth step, and then, preparing a slurry in the fifth step, thereby inhibiting reagglomeration of the antioxidant in the slurry while being combined with-SO 3 functional groups of side chains of PFSA fluorine-based ionomer,
after mixing the ionomer, performing the second dispersion to a degree lower than that of the first dispersion, thereby increasing the degree of freedom of the ionomer polymer, increasing electrostatic repulsive force caused by charges of functional groups of side chains, improving dispersibility of catalyst and ionomer in the slurry, thereby improving performance of the electrode-based membrane electrode assembly,
in the first step of the process, the first step is performed,
the antioxidant comprises at least one of cerium oxide, cerium zirconium oxide, tin dioxide, titanium dioxide, manganese carbonate and manganese dioxide,
the dispersion solvent comprises at least one of water, methanol, ethanol, n-propanol, isopropanol, butanol and ethylene glycol.
2. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim l,
in the second step, the first dispersion is performed by at least one of an ultrasonic generator, an ultrasonic probe, a homogenizer, and a stirrer.
3. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim 2,
in the fourth step, the second dispersion is performed by at least one of an ultrasonic generator, an ultrasonic probe, a homogenizer, a stirrer, a planetary stirrer, and a magnetic stirrer.
4. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim 3,
in the first step, at least one of a reverse voltage inhibitor and an additive for electrode pore formation and quality improvement is mixed in addition to the antioxidant.
5. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim 4,
in order to improve the dispersion of the antioxidant, the particles of the dried antioxidant powder having a predetermined size or more are crushed based on a mortar and pestle and/or a grinder before the first step, and the particles having a predetermined size or more are filtered by a mesh screen to homogenize the size of the antioxidant powder.
6. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim 5,
in the fifth step, in order to prevent the catalyst from being ignited when it comes into contact with the dispersion solvent, the catalyst mixed with water is used.
7. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim 6,
in the fifth step, the preparation of the slurry is performed by at least one of an ultrasonic generator, an ultrasonic probe, a homogenizer, a stirrer, and a magnetic stirrer.
8. The method for preparing a multi-step electrode slurry for improving the dispersibility of additives and ionomers in an electrode according to claim 7,
in the sixth step, the coating of the slurry is performed by at least one of a spray coater, a bar coater, and a slot die coater.
9. An electrode for a polyelectrolyte fuel cell produced by the production method according to any one of claims 1 to 8.
CN202310246362.8A 2022-07-20 2023-03-07 Multi-step electrode slurry preparation method for improving additive and ionomer dispersibility in electrode and electrode for polymer electrolyte fuel cell Pending CN117438594A (en)

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