High-durability catalyst layer as well as preparation method and application thereof

Abstract

The invention discloses a high-durability catalyst layer and a preparation method and application thereof, and the preparation method comprises the following steps: mixing an ionic polymer, water and an organic alcohol solvent to obtain an ionomer dispersion liquid; the ionomer dispersion liquid is subjected to gelation, and ionomer gel is obtained; mixing the ionomer gel with an inorganic functional material with the free radical quenching capability to obtain an inorganic functional material-ionomer blend with the free radical quenching capability; the preparation method comprises the following steps: mixing an inorganic functional material-ionomer blend with free radical quenching capacity, a catalyst and a solvent to obtain catalyst slurry; and coating the surface of the ion exchange membrane with the catalyst slurry, and drying to form the high-durability catalyst layer. Through ionomer pre-gelatinization and CeO2 particle blending, the synergistic technical breakthrough of CeO2 loading capacity improvement, CeO2 sedimentation inhibition and core performance loss is realized, the microstructure of the catalyst layer is not damaged, and the original aggregate form and electrochemical reaction three-phase interface stability are completely reserved.

Description

Technical Field

[0001] This application relates to the field of ion exchange membrane electrochemical device technology, and in particular to a highly durable catalyst layer, its preparation method, and its application. Background Technology

[0002] Ion exchange membrane electrochemical devices (including proton exchange membrane fuel cells, anion exchange membrane fuel cells, water electrolyzers, metal-air batteries, and acid / alkaline batteries) Electrolytic cells, etc., all use oxygen electrodes constructed from ionomers as their core. When this side operates under high potential and strong oxidation conditions, ORR, OER or their reverse reaction are continuously generated. Free radicals such as ·OH / ·OOH are easily attacked by the polymer skeleton, causing ion group shedding and carbon chain breakage. This leads to thinning of the catalyst layer, collapse of the pore structure and interface peeling, which has become a common bottleneck restricting the lifespan of various devices and systems.

[0003] To improve the chemical durability of membrane electrodes, introducing free radical quenchers into the membrane and catalyst layer has become a common choice in the industry. Traditional free radical quenchers are mainly inorganic metal oxide particles, with representative substances including cerium dioxide (CeO2) and manganese dioxide (MnO2). Among these, CeO2 is particularly effective due to its high cerium content. 3 With Ce 4 The reversible redox cycle of MnO2 has excellent and continuous free radical scavenging activity, and also has the advantages of low raw material cost and stable catalytic performance, making it the most widely used variety. Other inorganic oxides such as MnO2 achieve free radical capture through the redox reaction of their own multivalent ions, and also show good application potential.

[0004] However, the limitations of such traditional free radical quenchers in practical applications are becoming increasingly apparent: for pure CeO2, MnO2, and other oxides, the core problem is the easy agglomeration of particles and the presence of active ions (CeO2, MnO2, etc.). 3 / Ce 4 Mn 2 / Mn 3 / Mn 4 It is easily soluble and significantly hinders the ion conductivity of the system. From a microstructural perspective, the particle size of its aggregates is much larger than the size of the ion cluster channels in the proton exchange membrane, directly disrupting the migration pathway of hydrated protons. This leads to a sharp increase in ion conductivity resistance with increasing addition amount. At the same time, the uneven distribution of particles in the ionomer film easily forms local high-concentration regions. The ion conductivity of these regions decreases significantly, thus forming a performance "dead zone" and severely degrading the overall electrochemical performance of the membrane electrode.

[0005] Researchers have addressed this issue by modifying nanoparticles (e.g., doping, loading, surface coating) and developing organic-inorganic composite systems (e.g., Ce-based complexes). Modified materials have indeed shown significant improvements in dispersibility and uniformity compared to pure oxides, enabling them to more effectively exert free radical quenching effects. The complexes can also form good interfacial bonds with ionomers, reducing blockage of ion conduction channels and having a relatively small impact on membrane conductivity. However, the problems with the above solutions are: (1) poor thermal stability, with some complexes easily decomposing or being lost at battery operating temperatures, resulting in a significant decrease in quenching effect over long-term use; and (2) high preparation costs, especially the complex synthesis process of polymer grafted complexes. From an economic perspective, the mass production cost of these improved materials is far higher than that of commercially available oxide nanoparticles, limiting their promotion and popularization in the market. Most of these materials remain in the laboratory research and development stage.

[0006] Therefore, developing a catalytic layer that can improve thermal stability and reduce costs for use in membrane electrodes is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, this application provides a method for preparing a high-durability catalyst layer. By constructing a rigid three-dimensional network from gelled ionomers and intercalating it with free radical quenching inorganic oxide nanoparticles, the uniform dispersion of inorganic nanoparticles in the catalyst slurry preparation process is effectively achieved, overcoming the concentration limitations of traditional oxide nanoparticles as free radical quenchers.

[0008] This application provides a method for preparing a high-durability catalyst layer, including: An ionomer dispersion was obtained by mixing an ionomer, water, and an organic alcohol solvent. The ionomer dispersion was gelled to obtain an ionomer gel. Ionomer gels are mixed with inorganic functional materials with free radical quenching capabilities to obtain inorganic functional materials-ionomer blends with free radical quenching capabilities. An inorganic functional material-ionomer blend with free radical quenching ability, a catalyst, and a solvent are mixed to obtain a catalyst slurry. The catalyst slurry is coated onto the surface of the ion exchange membrane and dried to form a highly durable catalytic layer.

[0009] In some specific implementations, the ionic polymer includes one or more of the following: perfluorosulfonic acid type ionic polymer, highly oxygen-permeable sulfonic acid type ionic polymer, non-fluorosulfonic acid type ionic polymer, perfluorocarboxylic acid type ionic polymer, non-fluorocarboxylic acid type ionic polymer, phosphoric acid type ionic polymer, or quaternary ammonium type ionic polymer. The organic alcohol solvent includes one or more of methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, propylene glycol, diethylene glycol monomethyl ether, or fluoroalcohols. The mixing methods of the ionic polymer, water and organic alcohol solvent include one or more of the following: magnetic stirring, paddle stirring, drum mixing, oscillating mixing, shear dispersion, sand milling dispersion, grinding dispersion, ultrasonic dispersion, cell disruption, high pressure homogenization, microjet dispersion, microwave-assisted dispersion or supercritical fluid dispersion. The ionomer dispersion contains 1 wt% to 60 wt% of ionomer and has a water to organic alcohol mass ratio of (0.01-100):1.

[0010] In some specific implementations, the non-fluorosulfonic acid ionic polymer includes one or more of sulfonated aromatic hydrocarbons, sulfonated polyimides, sulfonated polyphenylene sulfonate, sulfonated polystyrene, or sulfonated polyolefins. The quaternary ammonium ionomer includes one or more of quaternary ammonium polyarylepiperidine, quaternary ammonium polyphenylene ether, quaternary ammonium polystyrene, or quaternary ammonium imidazoline.

[0011] In some specific implementations, the gelation method includes one or more of the following: high temperature induction, microwave-thermal induction, pH induction, solvent replacement, or hydroxylation molecule induction. The storage modulus G′ of the ionomer gel is 10. 1 Pa to 10 3 Pa, the yield stress satisfies τ_y = (3–10)×G′.

[0012] In some specific implementations, the inorganic functional material with free radical quenching ability includes one or more of Ce-based materials, Mn-based materials, Ti-based materials, Cr-based materials, Al-based materials, Co-based materials, Zr-based materials, or rare earth composite materials; The solution system of the inorganic functional material with free radical quenching ability has a pH ≤ 3, a solid content of 5 wt% to 50 wt%, a particle size D50 ≤ 20 nm, and the surfactant used in the system contains one or more of acetate, nitrate or citric acid. The solution system of the inorganic functional material with free radical quenching ability has a mass percentage content of 0.1 wt% to 50 wt% of the inorganic functional material with free radical quenching ability. The inorganic functional material-ionomer blend with free radical quenching ability has a mass fraction of 0.01 wt% to 30 wt%.

[0013] In some specific implementations, the inorganic functional materials with free radical quenching capabilities include CeO2, MnO2, TiO2, TiO2, Al2O3, Cr2O3, Co3O4, ZrO2, CeO2 / Al2O3, CeO2 / TiO2, CeO2 / ZrO2, Ce-Mn, Mn-Zr, Ce-Zr, Ce-Ti, Mn-Co, Ti-Zr, Ce-Mn-Zr, etc. Ce-Ti-Zr, Ce-Fe-Mn, Mn-Co-Zr, Ce-La-Zr, La-Mn-Co, Ce-Cr-Zr, Sm-Ce-Mn, Ce-La-O, La-C One or more of o-O, La-Mn-O, La-Cr-O, Nd-Mn-O, Sm-Ce-O, La-Mn-Co-O, Nd-Ce-Zr-O or Sm-La-Mn-O.

[0014] In some specific implementations, the catalyst slurry further includes one or more of a thickener, a pore-forming agent, a surfactant, a second ionomer, or conductive carbon; The thickener includes one or more of methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, or polyacrylate; The pore-forming agent includes one or more of the following: organic thermal decomposition pore-forming agents, inorganic carbonate pore-forming agents, or water-soluble small molecule pore-forming agents. The surfactant includes one or more of nonionic surfactants, anionic surfactants, or amphoteric surfactants. The second ionomer includes one or more of the following: perfluorosulfonic acid ionomers, partially fluorinated ionomers, or non-fluorinated proton-conducting ionomer solutions; The conductive carbon includes one or more of conductive carbon black, carbon nanotubes, graphene, carbon nanofibers, or porous carbon materials. The solid content of the catalyst slurry is 1% to 30%; The mass ratio of the inorganic functional material-ionomer blend with free radical quenching ability, the catalyst and the solvent is (0.1~30):(1~30):(70~99).

[0015] In some specific implementations, the mixing methods of the inorganic functional material-ionomer blend with free radical quenching ability, the catalyst and the solvent include one or more of the following: magnetic stirring, paddle stirring, drum mixing, oscillating mixing, shear dispersion, sand milling dispersion, grinding dispersion, ultrasonic dispersion, cell disruption, high pressure homogenization, microjet dispersion, microwave-assisted dispersion, and supercritical fluid dispersion. The methods for forming a highly durable catalyst layer include CCM and / or GDE; The ion exchange membrane includes one or more of the following: perfluorosulfonic acid membrane, high-temperature PBI membrane, sulfonated hydrocarbon membrane, carboxylic acid membrane, or phosphoric acid membrane; The coating includes one or more of spraying, scraping, roller coating or slot extrusion direct coating; The drying process includes one or more of the following: hot air, infrared, vacuum, microwave, UV-LED, spray drying, supercritical CO2, freeze drying, hot roller contact drying, microwave-hot air composite, or plasma-hot air coupling.

[0016] This application also provides a high-durability catalyst layer, which is prepared according to the preparation method described above.

[0017] This application also provides a membrane electrode, comprising a cathode gas diffusion layer, a cathode catalyst layer, an ion exchange membrane, an anode catalyst layer, and an anode gas diffusion layer arranged sequentially. The cathode catalyst layer is a high-durability catalyst layer prepared by the preparation method described above or the high-durability catalyst layer described above.

[0018] This application achieves a synergistic technological breakthrough by using a pre-gelling process of ionomers and blending with CeO2 particles, resulting in "increased CeO2 loading + suppressed CeO2 sedimentation + no damage to core performance." The technical effects are significant. The preparation method allows for the uniform dispersion of the free radical quenching additive CeO2 and effectively inhibits sedimentation. Due to its particle size compatibility with the catalyst layer, it does not damage the microstructure of the catalyst layer, fully preserving the original aggregate morphology and the stability of the three-phase interface in the electrochemical reaction. Furthermore, it increases the CeO2 loading in the membrane electrode by nearly 10 times compared to traditional processes, enabling in-situ and efficient quenching of hydroxyl radicals generated in the electrochemical reaction, reducing the impact of free radicals on the ion conductor and proton exchanger of the catalyst layer. The attack damage caused by membrane replacement significantly improves the chemical durability of the membrane electrode. At the same time, relying on the uniform distribution characteristics of CeO2 particles, the oxygen mass transfer resistance is not worsened by the introduction of additives, and the core performance indicators such as device power density are comparable to those of the blank control group, achieving a "non-destructive quenching" effect. In addition, the catalyst slurry using this process has excellent storage and use stability due to the gel network, providing reliable technical support for large-scale mass production. It also has a wide viscosity adjustment window and is compatible with various catalyst layer coating processes such as high-viscosity screen printing, medium-high viscosity slot coating, and low-viscosity spraying, fully demonstrating strong process adaptability and compatibility, and has broad prospects for industrial application. Attached Figure Description

[0019] Figure 1 Polarization curves of the high-durability catalyst layers provided in Examples 1-3, and the catalyst layers provided in Comparative Examples 1-3 and Comparative Example 5; Figure 2 The diagram shows the fluoride ion concentration in the tailwater of the high-durability catalyst layer provided in Example 3 and the catalyst layers provided in Comparative Examples 1 and 3. Figure 3 The rheological properties correlation curves of the high-durability catalyst layer provided in Example 3 and the catalyst layer provided in Comparative Example 3 are shown. Detailed Implementation

[0020] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0021] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0022] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions may be performed simultaneously.

[0023] The use of any and all instances or exemplary language such as “e.g.” or “include” in this document is intended merely to better illustrate the application and does not constitute a limitation on the scope of the application. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0024] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0025] With the rapid expansion of production capacity in fields such as proton exchange membrane fuel cells (PEMFC) and acid / alkaline water electrolysis for hydrogen production (PEM-WE, AEM-WE), the market has an urgent need for continuous, low-cost, and high-yield manufacturing of membrane electrodes. The severe agglomeration and sedimentation phenomena that occur in the traditional process of directly blending inorganic oxide-type free radical quencher nanoparticle dispersions into low-viscosity ionomer solutions are a significant technical challenge in the preparation of high-durability membrane electrode catalyst layers. This application addresses this pain point by innovatively employing a "pre-gelled ionomer" technology to form a continuous and stable three-dimensional porous framework. Nanoparticles enter these pores and are "anchored" to the network framework, preventing them from moving freely or agglomerating into large aggregates. This directly blocks the chain of action of "particle agglomeration → gravity dominance → particle sedimentation," effectively achieving uniform dispersion of nanoparticles during catalyst slurry preparation. This breaks through the concentration limit of traditional free radical quenchers and significantly improves the chemical durability of the catalyst layer. Simultaneously, the gel itself has a high system viscosity, which enhances the dispersion stability of particles in the network and prevents particles from directional migration and sedimentation due to gravity. This effectively improves the storage stability of the catalyst slurry, ensuring uniformity of catalyst layer coating, consistent loading, and high product yield during large-scale mass production. Furthermore, through precise control of the degree of gelation, precise matching between slurry viscosity and coating window can be effectively achieved, providing a universal platform for various mass production processes such as roll-to-roll slot coating, spraying, and screen printing.

[0026] This application provides a method for preparing a high-durability catalyst layer, including: An ionomer dispersion was obtained by mixing an ionomer, water, and an organic alcohol solvent. The ionomer dispersion was gelled to obtain an ionomer gel. Ionomer gels are mixed with inorganic functional materials with free radical quenching capabilities to obtain inorganic functional materials-ionomer blends with free radical quenching capabilities. An inorganic functional material-ionomer blend with free radical quenching ability, a catalyst, and a solvent are mixed to obtain a catalyst slurry. The catalyst slurry is coated onto the surface of the ion exchange membrane and dried to form a highly durable catalytic layer.

[0027] Structural Innovation: Breaking through the traditional "low viscosity blending" mindset, this innovative approach constructs a rigid three-dimensional network from gelled ionomers and intercalates it with free radical quenching inorganic oxide nanoparticles. This effectively achieves uniform dispersion of inorganic nanoparticles during catalyst slurry preparation, overcoming the concentration limitations of traditional oxide nanoparticles as free radical quenchers.

[0028] Process innovation: The high-viscosity catalyst slurry formed by gelled ionomers can significantly enhance the storage stability of each component of the slurry, including inorganic free radical quenchers, so as to ensure the uniformity of coating, loading consistency and product yield of this type of high-durability catalyst layer during large-scale mass production.

[0029] Innovative Applications: By adjusting the rheological properties of the slurry through crosslinking degree, this patented technology exhibits excellent adaptability and can be matched with various mass production processes such as roll-to-roll slot coating, spraying, and screen printing, thus expanding the application scope of the high-durability catalyst layer preparation technology in this application.

[0030] Durability Innovation: The high-content CeO2 fuel cell cathode catalyst layer prepared using patented technology reduces the amount of fluoride ions released by more than 70% compared to catalyst layers prepared using traditional additive processes.

[0031] This application first mixes an ionomer, water, and an organic alcohol solvent to obtain an ionomer dispersion. In some specific implementations, the ionomer includes one or more of the following: perfluorosulfonic acid ionomers, highly oxygen-permeable sulfonic acid ionomers, non-fluorosulfonic acid ionomers, perfluorocarboxylic acid ionomers, non-fluorocarboxylic acid ionomers, phosphoric acid ionomers, or quaternary ammonium ionomers. The organic alcohol solvents include, but are not limited to, one or more of methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, propylene glycol, diethylene glycol monomethyl ether, or fluoroalcohols. This application does not have any special requirements for the selection of organic alcohol solvents. The mixing methods of the ionic polymer, water and organic alcohol solvent include, but are not limited to, one or more of the following: magnetic stirring, paddle stirring, drum mixing, oscillating mixing, shear dispersion, sand milling dispersion, grinding dispersion, ultrasonic dispersion, cell disruption, high pressure homogenization, microjet dispersion, microwave-assisted dispersion or supercritical fluid dispersion. This application does not have any special requirements for the selection of the mixing method. The ionomer dispersion contains 1 wt% to 60 wt% of ionomer, preferably 2 wt% to 40 wt%, more preferably 5 wt% to 30 wt%, and even more preferably 4 wt% to 25 wt%, and the mass ratio of water to organic alcohol is (0.01-100):1, preferably (0.1-10):1.

[0032] In some specific implementations, the non-fluorosulfonic acid ionic polymer includes, but is not limited to, one or more of sulfonated aromatic hydrocarbons, sulfonated polyimides, sulfonated polyphenylene benzoylmiazole, sulfonated polystyrene, or sulfonated polyolefins. This application does not have any special requirements for the selection of non-fluorosulfonic acid ionic polymers. The quaternary ammonium ionomers include, but are not limited to, one or more of quaternary ammonium polyarylepiperidine, quaternary ammonium polyphenylene ether, quaternary ammonium polystyrene, or quaternary ammonium imidazoline. This application does not have any special requirements for the selection of quaternary ammonium ionomers.

[0033] This application then gels the ionomer dispersion to obtain an ionomer gel. In some specific implementations, the gelation method includes one or more of high-temperature induction, microwave-thermal induction, pH induction, solvent replacement, or hydroxylation molecule induction; the storage modulus G′ of the ionomer gel is 10. 1 Pa to 10 3 Pa, the yield stress satisfies τ_y = (3–10)×G′.

[0034] This application then mixes the ionomer gel with an inorganic functional material possessing free radical quenching ability to obtain an inorganic functional material-ionomer blend possessing free radical quenching ability. In some specific implementations, the inorganic functional material possessing free radical quenching ability includes one or more of Ce-based materials, Mn-based materials, Ti-based materials, Cr-based materials, Al-based materials, Co-based materials, Zr-based materials, or rare earth composite materials; The solution system of the inorganic functional material with free radical quenching ability has a pH ≤ 3, a solid content of 5 wt% to 50 wt%, a particle size D50 ≤ 20 nm, and the surfactant used in the system contains one or more of acetate, nitrate or citric acid. The solution system of the inorganic functional material with free radical quenching ability contains an inorganic functional material with free radical quenching ability at a mass percentage of 0.1 wt% to 50 wt%. During mixing, the gel storage modulus is kept to decrease by ≤50% to ensure uniform dispersion while avoiding damage to the three-dimensional network structure of the ionomer gel. The mass fraction of the inorganic functional material with free radical quenching ability in the inorganic functional material-ionomer blend is 0.01 wt% to 30 wt%.

[0035] In some specific implementations, the inorganic functional materials with free radical quenching capabilities include, but are not limited to, CeO2, MnO2, TiO2, TiO2, Al2O3, Cr2O3, Co3O4, Simple metal oxides, CeO2 / Al2O3, CeO2 / TiO2, CeO2 / ZrO2 and other oxide composite supports, Ce-Mn, Mn-Zr, Ce-Zr, Ce-Ti, Mn-Co, Ti-Zr and other binary composite oxides, Ce-Mn-Zr, Ce-Ti-Zr, Ce-Fe-Mn, Mn-Co-Zr, Ce-La-Zr, La-Mn-Co, Ce-Cr-Zr, etc. This application does not have any special requirements for the selection of inorganic functional materials with free radical quenching capabilities, such as multi-element composite oxides containing three or more metal elements such as Sm-Ce-Mn, binary and multi-element rare earth composite oxides such as Ce-La-O, La-Co-O, La-Mn-O, La-Cr-O, Nd-Mn-O, Sm-Ce-O, La-Mn-Co-O, Nd-Ce-Zr-O or Sm-La-Mn-O.

[0036] This application then mixes an inorganic functional material-ionomer blend with free radical quenching ability, a catalyst, and a solvent to obtain a catalyst slurry. In some specific implementations, the catalyst slurry further includes one or more of a thickener, a pore-forming agent, a surfactant, a second ionomer, or conductive carbon. The thickener includes, but is not limited to, one or more of methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, or polyacrylate. This application does not have any special requirements for the selection of thickener. The pore-forming agent includes, but is not limited to, one or more of organic thermal decomposable pore-forming agents, inorganic carbonate pore-forming agents, or water-soluble small molecule pore-forming agents. This application does not have any special requirements for the selection of pore-forming agents. The organic thermal decomposable pore-forming agents include ammonium carbonate and ammonium bicarbonate. The inorganic carbonate pore-forming agents include calcium carbonate and magnesium carbonate. The water-soluble small molecule pore-forming agents include polyethylene glycol and glucose.

[0037] The surfactants include, but are not limited to, one or more of nonionic surfactants, anionic surfactants, or amphoteric surfactants. This application does not have any special requirements for the selection of surfactants. The second ionomer includes one or more of the following: perfluorosulfonic acid ionomers, partially fluorinated ionomers, or non-fluorinated proton-conducting ionomer solutions; The conductive carbon includes one or more of conductive carbon black, carbon nanotubes, graphene, carbon nanofibers or porous carbon materials. This application does not have any special requirements for the selection of conductive carbon. The solid content of the catalyst slurry is 1% to 30%, preferably 3% to 20%; The mass ratio of the inorganic functional material-ionomer blend with free radical quenching ability, the catalyst and the solvent is (0.1~30):(1~30):(70~99).

[0038] In some specific implementations, the mixing methods of the inorganic functional material-ionomer blend with free radical quenching ability, the catalyst and the solvent include one or more of the following: magnetic stirring, paddle stirring, drum mixing, oscillating mixing, shear dispersion, sand milling dispersion, grinding dispersion, ultrasonic dispersion, cell disruption, high pressure homogenization, microjet dispersion, microwave-assisted dispersion, and supercritical fluid dispersion.

[0039] After the catalyst is thoroughly mixed with deionized water, it is then thoroughly mixed, dispersed, and degassed with the CeO2-ionomer blend solid, low-boiling-point organic alcohol, and other necessary additive components (thickener, pore-forming agent, surfactant, second ionomer, conductive carbon, etc.) to prepare the target catalyst slurry.

[0040] This application does not impose any limiting provisions on the preparation steps of the catalyst slurry, which may be as follows: Single-step method: Mixing and dispersing all components in one step; Multi-step method: step-by-step premixing, sequential feeding, staged heating / cooling, staged dispersion, staged degassing, etc.; Online continuous method: Real-time metering, mixing and dispersion of each component are achieved in pipelines using flow equipment; Offline batch method: The preparation is carried out on equipment such as reaction kettle, planetary dispersion, grinding dispersion, high-speed dispersion, three-roll mill, etc. Segmented energy method: disperse in segments according to the order of low-energy premixing, high-energy homogenization, and low-energy degassing, or vice versa, or alternately change the dispersion rate, dispersion time, dispersion temperature, etc. Vacuum / Pressure Method: Mixing, dispersing, or degassing under negative or positive pressure conditions; Any combination of two or more of the above methods, or any combination with other mixing, dispersing, degassing, or conveying means known in the art, falls within the scope of protection of this application.

[0041] This application then coats the catalyst slurry onto the surface of an ion exchange membrane, dries it, and forms a highly durable catalytic layer. In some specific implementations, the method for forming the highly durable catalytic layer includes CCM and / or GDE; The coating method can be: CCM route, in which the catalyst slurry is directly coated onto the surface of the ion exchange membrane, and after drying, a membrane with a catalyst coating on one side is obtained; further, a catalyst coating can be prepared on the uncoated surface of the membrane to form a CCM structure; The GDE route involves coating the catalyst slurry onto the surface of the microporous layer of the gas diffusion layer, and after drying, obtaining a GDE structure with a catalyst coating on one side. The ion exchange membrane should be selected according to the working medium, temperature and ion conduction type of the application scenario (such as fuel cell, water electrolyzer, CO2RR electrolyzer, metal-air battery or flow battery), and accordingly, such as perfluorosulfonic acid membrane, high temperature PBI membrane, sulfonated hydrocarbon membrane, carboxylic acid / phosphate membrane or any ion exchange membrane that meets the requirements of ion conduction and mechanical strength.

[0042] This application does not specifically limit the coating method. Depending on the solid content and rheological properties of the slurry, various coating preparation methods such as spraying, scraping, roller coating, and slot extrusion direct coating can be used. Preferably, based on the high-volume roll-to-roll catalyst layer manufacturing process, a slot extrusion coating method can be used.

[0043] This application does not specifically limit the drying method. Depending on the coating scheme and slurry characteristics, the drying step is selected from one or more combinations of hot air, infrared, vacuum, microwave, UV-LED, spray drying, supercritical CO2, freeze drying, hot roller contact drying, microwave-hot air composite, and plasma-hot air coupling. After the drying process, the residual solvent in the catalyst layer is <2 wt%, and the coating surface is free of cracks and warping.

[0044] The ion exchange membrane includes one or more of the following: perfluorosulfonic acid membrane, high-temperature PBI membrane, sulfonated hydrocarbon membrane, carboxylic acid membrane, or phosphoric acid membrane; The coating includes one or more of spraying, scraping, roller coating or slot extrusion direct coating; The drying process includes one or more of the following: hot air, infrared, vacuum, microwave, UV-LED, spray drying, supercritical CO2, freeze drying, hot roller contact drying, microwave-hot air composite, or plasma-hot air coupling.

[0045] This application also provides a high-durability catalyst layer, which is prepared according to the preparation method described above.

[0046] In some specific implementations, the thickness of the high-durability catalyst layer is from 1 μm to 100 μm.

[0047] This application also provides a membrane electrode, comprising a cathode gas diffusion layer, a cathode catalyst layer, an ion exchange membrane, an anode catalyst layer, and an anode gas diffusion layer arranged sequentially. The cathode catalyst layer is a high-durability catalyst layer prepared by the preparation method described above or the high-durability catalyst layer described above.

[0048] The gas diffusion layer should be designed according to the application scenario requirements (such as fuel cells, water electrolysis cells, etc.). For electrolytic cells, metal-air batteries, or flow batteries, appropriate materials such as carbon paper, carbon cloth, metal fiber felt, or ceramic composite felt can be selected.

[0049] The obtained catalyst layer, ion exchange membrane, gas diffusion layer or corresponding composite component are sequentially assembled with the sealing frame, and then hot-pressed or cold-pressed to obtain the membrane electrode assembly; the frame provides sealing and mechanical support, and the integration process meets the requirement that the sealing leakage rate is <10%. -6 sccm cm -2 .

[0050] The present application is further illustrated below with reference to embodiments. The scope of protection of the present application is not limited to the following embodiments.

[0051] Example 1

[0052] This embodiment provides a high-durability catalyst layer. The catalyst contained in the high-durability catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: Ionomer solid, deionized water, and n-propanol were mixed in a mass ratio of 1:3:10 and stirred overnight to form an ionomer dispersion. The dispersion was then added to a reflux reflux apparatus and heated to 80 °C to allow the polymer chains to fully extend and establish hydrogen bonds for pre-crosslinking, resulting in an ionomer gel with a storage modulus of 90 Pa (25 °C, 1 Hz) and a dynamic yield stress of 602 Pa (1 Hz oscillating stress scan, G' = G” crossover point).

[0053] A 20% commercially available CeO2 aqueous solution was mixed with an ionomer gel, and the CeO2 was uniformly dispersed into the ionomer system by planetary stirring to obtain a blend system with a storage modulus of 77 Pa (25 °C, 1 Hz). The mass fraction of CeO2 in the mixture was 5 wt% relative to the total solids. The commercially available CeO2 aqueous solution used acetate as a stabilizer, and the pH was <3. Small-angle X-ray scattering (SAXS) analysis showed that the average particle size of the CeO2 particles in this mixture was 17.6 nm.

[0054] The catalyst, deionized water, CeO2-ionomer gel, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0055] The collected slurry was vacuum degassed. The slurry had a solid content of 11 wt% and a viscosity of 170 cP (25). o C, 100s -1 ).

[0056] A cathode catalyst layer was coated onto the surface of an ion exchange membrane using a slit extrusion coating method. 90 o The cathode catalyst layer is dried with hot air for at least 5 minutes at C, and the platinum loading is 0.3 mg.Pt / cm 2 The ion exchange membrane is an M765.08 manufactured by Gore, Inc., USA.

[0057] Example 2

[0058] This embodiment provides a high-durability catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; and the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: Ionomer solid, deionized water, and n-propanol were mixed in a mass ratio of 1:3:10 and stirred overnight to form an ionomer dispersion. The dispersion was then added to a reflux reflux apparatus and heated to 80 °C to allow the polymer chains to fully extend and establish hydrogen bonds for pre-crosslinking, resulting in an ionomer gel with a storage modulus of 90 Pa (25 °C, 1 Hz) and a dynamic yield stress of 602 Pa (1 Hz oscillating stress scan, G' = G” crossover point).

[0059] A 20% commercially available CeO2 aqueous solution was mixed with an ionomer gel, and the CeO2 was uniformly dispersed into the ionomer system by planetary stirring to obtain a blend system with a storage modulus of 77 Pa (25 °C, 1 Hz). The mass fraction of CeO2 in the mixture was 5 wt% relative to the total solids. The commercially available CeO2 aqueous solution used acetate as a stabilizer, and the pH was <3. Small-angle X-ray scattering (SAXS) analysis showed that the average particle size of the CeO2 particles in this mixture was 17.6 nm.

[0060] The catalyst, deionized water, CeO2-ionomer gel, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0061] The collected slurry was vacuum degassed, and then diluted with a certain amount of water-alcohol mixed solvent to a solid content of 3 wt% and a viscosity of 15 cP (25 ℃, 100 s). -1 ).

[0062] A cathode catalyst layer was coated onto the surface of an ion exchange membrane using ultrasonic spraying. The temperature of the vacuum adsorption hot plate was 120°C, and the platinum loading of the cathode catalyst layer was 0.3 mg. Pt / cm 2 .

[0063] Example 3

[0064] This embodiment provides a high-durability catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50%; the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: Ionomer solid, deionized water, and n-propanol were mixed in a mass ratio of 1:4:6 and stirred overnight to form an ionomer dispersion. The dispersion was then added to a reflux reflux apparatus and heated to 80°C. o C allows the polymer chains to fully extend and establish hydrogen bond pre-crosslinking, resulting in an ionomer gel with a storage modulus of 150 Pa (25 ℃, 1 Hz) and a dynamic yield stress of 725 Pa (1 Hz oscillating stress scan, G' = G” cross point).

[0065] A 20% commercially available CeO2 aqueous solution was mixed with an ionomer gel, and the CeO2 was uniformly dispersed into the ionomer system by planetary stirring to obtain a blend system with a storage modulus of 83 Pa (25 °C, 1 Hz). The mass fraction of CeO2 in the mixture was 30 wt% relative to the total solids. The commercially available CeO2 aqueous solution used acetate as a stabilizer, with a pH < 3. Small-angle X-ray scattering (SAXS) analysis showed that the average particle size of the CeO2 particles in this mixture was 19.2 nm.

[0066] The catalyst, deionized water, CeO2-ionomer gel, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0067] The collected slurry was vacuum degassed. The slurry had a solid content of 14 wt% and a viscosity of 363 cP (25 °C, 100 s). -1 ).

[0068] A cathode catalyst layer was coated onto the surface of an ion exchange membrane using a direct coating method with a doctor blade, and then dried with hot air at 90 °C for at least 5 minutes. The platinum loading of the cathode catalyst layer was 0.3 mg. Pt / cm 2 .

[0069] Comparative Example 1

[0070] This comparative example provides a catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; and the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: Ionomer solid, deionized water, and n-propanol were mixed in a mass ratio of 1:3:10 and stirred overnight to form an ionomer dispersion. The dispersion was then added to a reflux reflux apparatus and heated to 80 °C to allow the polymer chains to fully extend and establish hydrogen bonds for pre-crosslinking, resulting in an ionomer gel with a storage modulus of 90 Pa (25 °C, 1 Hz) and a dynamic yield stress of 602 Pa (1 Hz oscillating stress scan, G' = G” crossover point).

[0071] The catalyst, deionized water, and ionomer gel were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0072] The collected slurry was vacuum degassed. The slurry had a solid content of 11 wt% and a viscosity of 168 cP (25 °C, 100 s). -1 ).

[0073] A cathode catalyst layer was coated on the surface of an ion exchange membrane using a slit extrusion coating method, and then dried with hot air at 90 °C for at least 5 minutes. The platinum loading of the cathode catalyst layer was 0.3 mg. Pt / cm 2 .

[0074] Comparative Example 2

[0075] This comparative example provides a catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; and the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: An ionomer stock solution, deionized water, and n-propanol were thoroughly mixed at a mass ratio of 5:1:15 to form an ionomer dispersion. While the dispersion was magnetically stirred, a commercially available CeO2 aqueous solution was slowly added dropwise. The stabilizer in the commercially available CeO2 aqueous solution was acetate, and the pH was <3. During the gradual addition, obvious flocculent precipitates appeared in the solution. These flocculent precipitates were CeO2 aggregates with disrupted surface charge stability. When the mass fraction of CeO2 in the mixture was 5 wt% relative to the total solids, the particle size distribution of the CeO2 aggregates in the mixture, measured by a laser particle size analyzer, showed a D50 of 80 nm.

[0076] The catalyst, deionized water, CeO2 aggregate-ionomer mixture, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0077] The collected slurry was vacuum degassed. The slurry had a solid content of 11 wt% and a viscosity of 55 cP (25 °C, 100 s). -1 ).

[0078] A cathode catalyst layer was coated on the surface of an ion exchange membrane using a slit extrusion coating method, and then dried with hot air at 90 °C for at least 5 minutes. The platinum loading of the cathode catalyst layer was 0.3 mg. Pt / cm 2 .

[0079] Comparative Example 3

[0080] This comparative example provides a catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; and the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: An ionomer stock solution, deionized water, and n-propanol were thoroughly mixed at a mass ratio of 5:1:15 to form an ionomer dispersion. While the dispersion was magnetically stirred, a commercially available CeO2 aqueous solution was slowly added dropwise. The stabilizer in the commercially available CeO2 aqueous solution was acetate, and the pH was <3. During the gradual addition, obvious flocculent precipitate appeared in the solution. This flocculent precipitate consisted of CeO2 agglomerates with disrupted surface charge stability. When the mass fraction of CeO2 in the mixture was 3 wt% relative to the total solids, the particle size distribution of the CeO2 agglomerates in the mixture, measured by a laser particle size analyzer, showed a D50 of 39 nm.

[0081] The catalyst, deionized water, CeO2 aggregate-ionomer mixture, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0082] The collected slurry was vacuum degassed. The slurry had a solid content of 11 wt% and a viscosity of 53 cP (25 °C, 100 s). -1 ).

[0083] A cathode catalyst layer was coated on the surface of an ion exchange membrane using a slit extrusion coating method, and then dried with hot air at 90 °C for at least 5 minutes. The platinum loading of the cathode catalyst layer was 0.3 mg. Pt / cm 2 .

[0084] Comparative Example 4

[0085] This comparative example provides a catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: Ionomer solid, deionized water, and n-propanol were mixed in a mass ratio of 1:3:5 and stirred overnight to form an ionomer dispersion. The dispersion was then added to a reflux reflux apparatus and heated to 80 °C to allow the polymer chains to fully extend and establish hydrogen bonds for pre-crosslinking, resulting in an ionomer gel with a storage modulus of 170 Pa (25 °C, 1 Hz) and a dynamic yield stress of 764 Pa (1 Hz oscillating stress scan, G' = G” crossover point).

[0086] A 20% commercially available CeO2 aqueous solution was mixed with an ionomer gel, and the CeO2 was uniformly dispersed into the ionomer system using planetary stirring to obtain a blend system with a storage modulus of 52 Pa (25 °C, 1 Hz). The mass fraction of CeO2 in the mixture was 40 wt% relative to the total solids. The commercially available CeO2 aqueous solution used acetate as a stabilizer, and the pH was <3. The storage modulus of this CeO2-ionomer blend system decreased by 69.4% compared to the storage modulus of the unmixed ionomer gel. Small-angle X-ray scattering (SAXS) tests and data fitting showed that the average particle size of CeO2 in this blend system was 17.4 nm.

[0087] The catalyst, deionized water, CeO2-ionomer gel, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0088] The collected slurry was vacuum degassed. The slurry had a solid content of 8 wt% and a viscosity of 34 cP (25℃, 100s). -1 ).

[0089] A cathode catalyst layer was coated onto the surface of an ion exchange membrane using a slit extrusion coating method and dried with hot air at 90 °C for at least 5 minutes. After drying, the coating could be easily detached by light touch, with a clear detachment interface mainly located at the contact interface between the catalyst layer and the proton exchange membrane. The detached catalyst layer was in a complete sheet shape without obvious fragmentation, indicating that the internal adhesion of the coating was higher than the interfacial adhesion between the coating and the proton exchange membrane. Very little catalyst layer remained on the surface of the proton exchange membrane, and the interface was smooth.

[0090] Comparative Example 5

[0091] This comparative example provides a catalyst layer, which is a cathode catalyst layer for a fuel cell. The catalyst contained in this catalyst layer is a commercially available Pt / C catalyst, wherein the platinum mass fraction is 50 wt%; and the contained ionomer has an ion equivalent of 800 gmol. -1 A perfluorosulfonic acid type ionic polymer. The specific preparation method is as follows: Ionomer solid, deionized water, and n-propanol were mixed in a mass ratio of 1:3:5 and stirred overnight to form an ionomer dispersion. The dispersion was then added to a reflux reflux apparatus and heated to 80 °C to allow the polymer chains to fully extend and establish hydrogen bonds for pre-crosslinking, resulting in an ionomer gel with a storage modulus of 170 Pa (25 °C, 1 Hz) and a dynamic yield stress of 764 Pa (1 Hz oscillating stress scan, G' = G” crossover point).

[0092] A 20% commercially available CeO2 aqueous solution was mixed with an ionomer gel, and the CeO2 was uniformly dispersed into the ionomer system using planetary stirring to obtain a blend system with a storage modulus of 24 Pa (25℃, 1 Hz). The mass fraction of CeO2 in the blend system relative to the total solids was 45 wt%. The commercially available CeO2 aqueous solution used acetate as a stabilizer, and the pH was <3. The storage modulus of this CeO2-ionomer blend system decreased by 85.9% compared to the storage modulus of the unmixed ionomer gel. Small-angle X-ray scattering (SAXS) tests and data fitting showed that the average particle size of CeO2 in this blend system was 18.2 nm.

[0093] The catalyst, deionized water, CeO2-ionomer gel, and ethanol were added to a grinding jar in a certain proportion and dispersed by ball milling for 15 minutes to obtain a catalyst slurry. The ball milling speed was 1000 rpm, and the mass ratio of perfluorosulfonic acid ionomer solid to carbon was 1:1.

[0094] The collected slurry was vacuum degassed, and then diluted with a certain amount of water-alcohol mixed solvent to a solid content of 3 wt% and a viscosity of 11 cP (25 ℃, 100 s). -1 ).

[0095] A cathode catalyst layer was coated onto the surface of an ion exchange membrane using ultrasonic spraying. The temperature of the vacuum adsorption hot plate was 120°C, and the platinum loading of the cathode catalyst layer was 0.3 mg. Pt / cm 2 .

[0096] In all the above embodiments and comparative examples, the anode catalyst layer corresponding to the cathode catalyst layer uses the same process formulation and preparation method, and the platinum loading of the anode catalyst layer is 0.05 mg. Pt / cm 2 ; In Examples 1, 3, and Comparative Examples 1-4, the average thickness of the cathode catalyst layer obtained by slit coating or blade coating was 9 μm. In Examples 2 and 5, the average thickness of the cathode catalyst layer obtained by ultrasonic spraying was 16 μm. In all examples and comparative examples, the anode catalyst layer was prepared using the same process, and the thickness of the anode catalyst layer was 3 μm.

[0097] The particle size and distribution of CeO2 particles in CeO2-ionomer gel were analyzed using a Sinop Xeuss series small-angle X-ray scattering instrument. A copper target X-ray source (30W power, wavelength 1.54189 Å) was used as the background sample to subtract baseline noise. The original scattering intensity-scattering vector (Iq) data of the sample were normalized. Based on the hard spherical particle model assumption, the Iq curve was fitted and converted into a particle size-normalized probability density distribution curve. The volume average particle size and distribution width index of CeO2 particles were extracted to achieve quantitative characterization of the particle dispersion state.

[0098] The particle size and distribution of CeO2 particles in the CeO2-ionomer solution were characterized using a Malvern 3000 laser particle size analyzer. A deionized water-ethanol mixture was used as the dispersion medium, and the refractive index parameter was set (particle refractive index 2.2, and the refractive index of the dispersion medium was calibrated according to the ratio of the mixture). The sample was added to the dispersion medium in wet dispersion mode, and laser scattering signals were collected. The particle size distribution was calculated based on Mie scattering theory, and the particle size-volume fraction distribution curve was extracted. The D50 was used as the median particle size to quantitatively evaluate the dispersion state of CeO2 particles in the solution system.

[0099] The rheological properties of CeO2-ionomer gel and catalyst slurry were quantitatively analyzed using an Anton Paar MCR series rotational rheometer. A CC-27 coaxial cylindrical rotor was used, and the test temperature was 25 ℃. The storage modulus and loss modulus were tested in dynamic oscillation mode to determine the structural strength of the system. The viscosity was tested in steady-state shear mode to evaluate the storage stability and process adaptability of the slurry.

[0100] The cathode catalyst layers of the above embodiments and comparative examples were prepared with an active area of ​​25 cm². 2 Membrane electrode assembly for fuel cells was assembled and tested as a hydrogen-air single cell. The test conditions were: cell temperature 80℃, anode relative humidity 100%, cathode relative humidity 100%, anode back pressure 50 kPa, and cathode back pressure 50 kPa.

[0101] The above-mentioned membrane electrode was subjected to chemical durability open-circuit voltage (OCV) testing. The cell temperature was 90 °C, the anode relative humidity was 30%, the cathode relative humidity was 30%, the anode back pressure was 50 kPa, and the cathode back pressure was 50 kPa. The open-circuit voltage was maintained for continuous operation for 24 hours. The cathode-side tailwater of each cell was collected in real time, and fluoride ions in the cathode tailwater were analyzed using an ICS5000 ion chromatograph. The concentration of fluoride ions was quantitatively detected, and the degree of degradation of the ionomer was indirectly characterized by the amount of fluoride ions released, thereby evaluating the effect on improving the chemical durability of the membrane electrode.

[0102] Examples 1 to 3 focus on the core technical route of dispersing CeO2 with ionomer gel and adapting the slurry to various coating processes with a wide viscosity window. By controlling the amount of CeO2 added and the rheological properties of the slurry, the dual goals of maintaining the electrochemical performance of the membrane electrode and improving the chemical durability of the catalyst layer are achieved. The specific analysis is as follows: The core objective of Example 1 was to develop a medium-viscosity catalyst slurry suitable for slot extrusion coating, while simultaneously verifying the optimizing effect of low CeO2 addition (5 wt%) on catalyst layer performance. Compared to the blank system without CeO2 (Comparative Example 1), the pre-gelled network restricted the migration and aggregation of CeO2 particles while preserving the integrity of the three-phase interface of the catalyst layer. Therefore, its electrochemical performance was comparable to that of Comparative Example 1 (blank group), as shown in [reference needed]. Figure 1 , Figure 1 Polarization curves of the high-durability catalyst layers provided in Examples 1-3, and the catalyst layers provided in Comparative Examples 1-3 and Comparative Example 5.

[0103] Example 2 is a process extension based on Example 1. Its core objective is to verify that the viscosity of the pre-gelled slurry can be controlled through dilution, adapting it to a low-viscosity-dependent ultrasonic spraying process. The same CeO2-ionomer gel preparation process as in Example 1 is used to ensure consistent CeO2 dispersion. The original slurry is diluted with a mixed solvent to meet the low-viscosity requirements of ultrasonic spraying, while preventing CeO2 particle agglomeration due to dilution. Comparative Example 2 uses the same amount of CeO2; due to the lack of a stabilizing effect of the ionomer gel network, CeO2 particle agglomeration is significant. Since the performance of Example 2 is comparable to that of Comparative Example 1 (blank group), it further demonstrates the uniform dispersion of CeO2 within the slurry system. In comparison, Comparative Example 2 shows a significant decrease in membrane electrode performance, especially in the high-current-density mass transfer region, due to the larger particle size of CeO2 agglomerates within its catalyst layer. (See Figure 1 for details.) Figure 1 As shown in Comparative Example 3, the upper limit of CeO2 addition for non-destructive performance of membrane electrodes in traditional processes is only 3 wt%. Therefore, the solution in this application can increase the non-destructive addition amount by 10 times.

[0104] The core objective of Example 3 was to explore the maximum addition threshold of CeO2 and verify that the ionomer gel network could maintain structural stability even with an addition of 30 wt% CeO2. By increasing the storage modulus of the ionomer gel (150 Pa), the supporting capacity of the gel network could be enhanced to meet the dispersion requirements of high CeO2 content. Small-angle X-ray scattering (SAXS) tests showed that the average particle size was only 19.2 nm, slightly higher than in Example 1, but no agglomeration was observed, proving that the steric hindrance effect of the gel network could effectively suppress particle aggregation. A high-solids-content, high-viscosity slurry was prepared to suit the direct-coating process. Static storage stability tests verified that the slurry's storage modulus fluctuation was <10%, indicating a stable gel network structure and no risk of CeO2 sedimentation. Figure 1 It can be seen that the addition of 30 wt% CeO2 can still achieve the goal of non-destructive performance of membrane electrode.

[0105] Chemical durability tests were conducted on the membrane electrode samples of Example 3, Comparative Example 1 (blank baseline), and Comparative Example 3, which showed no performance degradation. The concentration of fluoride ions in the cathode tailwater was used to determine the chemical durability. Figure 2 , Figure 2 The diagram shows the fluoride ion concentration in the tailwater of the high-durability catalyst layer provided in Example 3 and the catalyst layers provided in Comparative Examples 1 and 3. The fluoride ion release in Example 3 is reduced by more than 70% compared to Comparative Example 3, which directly proves that the optimized design of this application significantly improves the chemical durability of the membrane electrode.

[0106] Rheological tests were performed on the catalyst slurries of Example 3, which used an ionomer gel preparation process, and Comparative Example 3, which used a conventional slurry preparation process. (See attached figures.) Figure 3 , Figure 3 The rheological property correlation curves of the high-durability catalyst layer provided in Example 3 and the catalyst layer provided in Comparative Example 3 are shown at 25 °C and 0.1 s. -1 Under the given conditions, the viscosity of the slurry in Example 3 was 79083 cP, indicating that its slurry structure can effectively suppress particle sedimentation and has excellent storage stability; while the viscosity of the slurry in Comparative Example 3 was only 159 cP, indicating that its static support strength was insufficient, and there was a risk of particle sedimentation during long-term storage, which did not meet the requirements for large-scale production and storage.

[0107] In Comparative Examples 4 and 5, the storage modulus of the ionomer gel was further increased to 170 Pa. However, due to the excessive addition of CeO2, the storage modulus of the CeO2-ionomer blend system decreased by 69.4% and 85.9% respectively compared to the storage modulus of the ionomer gel before mixing. Although the average particle size of CeO2 particles did not increase compared to Examples 1 to 3, it indicates that the gel system can still maintain the stability of CeO2 particles at this time.

[0108] However, in Comparative Example 4, the slit-coated coating peeled off entirely after drying. This directly indicates that the excessive CeO2 addition exceeded the adhesion compatibility threshold of the ionomer gel. Even if the ionomer gel system can temporarily inhibit CeO2 particle aggregation, excessive CeO2 will still completely destroy the interfacial interaction mechanism between the ionomer and the proton exchange membrane. The core problem is that the excessive CeO2 addition prevents the ionomer from forming a continuous adhesive network at the interface between the coating and the proton exchange membrane. Furthermore, the low polarity of CeO2 covers the hydrophilic active sites of the ionomer, causing the coating and the proton exchange membrane to lose key binding forces such as hydrogen bonds and ionic bonds, forming only a fragile physical contact. At the same time, the interfacial stress concentration and microstructural defects caused by excessive CeO2 further exacerbate the instability of the interfacial bonding, ultimately leading to the overall peeling off of the coating after drying. This proves that the CeO2 addition must be strictly controlled within the compatibility range of the ionomer gel; otherwise, the adhesion ability between the coating and the proton exchange membrane will be completely lost.

[0109] In Comparative Example 5, the dilution ultrasonic spraying method achieved the goal of preventing coating peeling. This phenomenon indicates that the spraying process can alleviate the interfacial adhesion problem caused by high CeO2 addition to a certain extent and improve the interfacial contact state. However, the significant decrease in battery performance still occurred in Comparative Example 5, where the coating did not peel off. The core reason is that ultrasonic spraying and dilution treatment cannot solve the inherent functional defects caused by high CeO2 addition. On the one hand, CeO2, as a non-proton conductor, occupies a large amount of the effective distribution space of the ionomer and covers the active sites of the sulfonic acid groups of the ionomer, causing the ionomer to be unable to build a continuous proton transport channel, resulting in a significant increase in proton transport resistance inside the electrode. On the other hand, CeO2 is not conductive, and its excessive presence will hinder the effective contact between conductive carbon carriers, disrupting the continuity of the electron transport network and leading to a decrease in the electrochemical reaction kinetic rate. This result shows that process adjustment can only optimize the interfacial bonding state between the coating and the proton exchange membrane, but cannot change the damage caused by high CeO2 addition to the ionomer function (proton conduction, bonding) and the electrode conductive network. Reasonable control of CeO2 addition is still the core to ensure the overall performance of the membrane electrode.

[0110] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and application concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for preparing a highly durable catalyst layer, characterized in that, include: An ionomer dispersion was obtained by mixing an ionomer, water, and an organic alcohol solvent. The ionomer dispersion was gelled to obtain an ionomer gel. Ionomer gels are mixed with inorganic functional materials with free radical quenching capabilities to obtain inorganic functional materials-ionomer blends with free radical quenching capabilities. An inorganic functional material-ionomer blend with free radical quenching ability, a catalyst, and a solvent are mixed to obtain a catalyst slurry. The catalyst slurry is coated onto the surface of the ion exchange membrane and dried to form a highly durable catalytic layer.

2. The preparation method according to claim 1, characterized in that, The ionic polymer includes one or more of the following: perfluorosulfonic acid type ionic polymer, highly oxygen-permeable sulfonic acid type ionic polymer, non-fluorosulfonic acid type ionic polymer, perfluorocarboxylic acid type ionic polymer, non-fluorocarboxylic acid type ionic polymer, phosphoric acid type ionic polymer, or quaternary ammonium type ionic polymer. The organic alcohol solvent includes one or more of methanol, ethanol, n-propanol, isopropanol, butanol, ethylene glycol, propylene glycol, diethylene glycol monomethyl ether, or fluoroalcohols. The mixing methods of the ionic polymer, water and organic alcohol solvent include one or more of the following: magnetic stirring, paddle stirring, drum mixing, oscillating mixing, shear dispersion, sand milling dispersion, grinding dispersion, ultrasonic dispersion, cell disruption, high pressure homogenization, microjet dispersion, microwave-assisted dispersion or supercritical fluid dispersion. The ionomer dispersion contains 1 wt% to 60 wt% of ionomer and has a water to organic alcohol mass ratio of (0.01-100):

1.

3. The preparation method according to claim 2, characterized in that, The non-fluorosulfonic acid ionic polymer includes one or more of sulfonated aromatic hydrocarbons, sulfonated polyimides, sulfonated polyphenylene sulfonates, sulfonated polystyrene, or sulfonated polyolefins. The quaternary ammonium ionomer includes one or more of quaternary ammonium polyarylepiperidine, quaternary ammonium polyphenylene ether, quaternary ammonium polystyrene, or quaternary ammonium imidazoline.

4. The preparation method according to claim 1, characterized in that, The gelation method includes one or more of the following: high temperature induction, microwave-thermal induction, pH induction, solvent replacement, or hydroxylation molecule induction; The storage modulus G′ of the ionomer gel is 10. 1 Pa to 10 3 Pa, the yield stress satisfies τ_y = (3–10)×G′.

5. The preparation method according to claim 1, characterized in that, The inorganic functional materials with free radical quenching ability include one or more of Ce-based materials, Mn-based materials, Ti-based materials, Cr-based materials, Al-based materials, Co-based materials, Zr-based materials, or rare earth composite materials; The solution system of the inorganic functional material with free radical quenching ability has a pH ≤ 3, a solid content of 5 wt% to 50 wt%, a particle size D50 ≤ 20 nm, and the surfactant used in the system contains one or more of acetate, nitrate or citric acid. The solution system of the inorganic functional material with free radical quenching ability has a mass percentage content of 0.1 wt% to 50 wt% of the inorganic functional material with free radical quenching ability. The inorganic functional material-ionomer blend with free radical quenching ability has a mass fraction of 0.01 wt% to 30 wt%.

6. The preparation method according to claim 1, characterized in that, The inorganic functional materials with free radical quenching capabilities include CeO2, MnO2, TiO2, TiO2, Al2O3, Cr2O3, and Co3O4. , CeO2 / Al2O3, CeO2 / TiO2, CeO2 / ZrO2, Ce-Mn, Mn-Zr, Ce-Zr, Ce-Ti, Mn-Co, Ti-Zr, Ce-Mn-Zr, Ce-Ti-Zr, Ce-Fe-Mn, Mn-Co-Zr, Ce-La-Zr, L One or more of a-Mn-Co, Ce-Cr-Zr, Sm-Ce-Mn, Ce-La-O, La-Co-O, La-Mn-O, La-Cr-O, Nd-Mn-O, Sm-Ce-O, La-Mn-Co-O, Nd-Ce-Zr-O or Sm-La-Mn-O.

7. The preparation method according to claim 1, characterized in that, The catalyst slurry also includes one or more of the following: thickener, pore-forming agent, surfactant, second ionomer, or conductive carbon; The thickener includes one or more of methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, or polyacrylate; The pore-forming agent includes one or more of the following: organic thermal decomposition pore-forming agents, inorganic carbonate pore-forming agents, or water-soluble small molecule pore-forming agents. The surfactant includes one or more of nonionic surfactants, anionic surfactants, or amphoteric surfactants. The second ionomer includes one or more of the following: perfluorosulfonic acid ionomers, partially fluorinated ionomers, or non-fluorinated proton-conducting ionomer solutions; The conductive carbon includes one or more of conductive carbon black, carbon nanotubes, graphene, carbon nanofibers, or porous carbon materials. The solid content of the catalyst slurry is 1% to 30%; The mass ratio of the inorganic functional material-ionomer blend with free radical quenching ability, the catalyst and the solvent is (0.1~30):(1~30):(70~99).

8. The preparation method according to claim 1, characterized in that, The mixing methods in the inorganic functional material-ionomer blend with free radical quenching ability, catalyst and solvent mixture include one or more of the following: magnetic stirring, paddle stirring, drum mixing, oscillating mixing, shear dispersion, sand milling dispersion, grinding dispersion, ultrasonic dispersion, cell disruption, high pressure homogenization, microjet dispersion, microwave-assisted dispersion, and supercritical fluid dispersion. The methods for forming a highly durable catalyst layer include CCM and / or GDE; The ion exchange membrane includes one or more of the following: perfluorosulfonic acid membrane, high-temperature PBI membrane, sulfonated hydrocarbon membrane, carboxylic acid membrane, or phosphoric acid membrane; The coating includes one or more of spraying, scraping, roller coating or slot extrusion direct coating; The drying process includes hot air, infrared, vacuum, microwave, UV-LED, spray drying, and supercritical drying. One or more of the following: freeze drying, hot roller contact drying, microwave-hot air composite or plasma-hot air coupling.

9. A highly durable catalyst layer, characterized in that, The high-durability catalyst layer is prepared according to the preparation method described in any one of claims 1 to 8.

10. A membrane electrode, characterized in that, It includes a cathode gas diffusion layer, a cathode catalyst layer, an ion exchange membrane, an anode catalyst layer, and an anode gas diffusion layer arranged sequentially. The cathode catalyst layer is a high-durability catalyst layer prepared by the preparation method according to any one of claims 1 to 8 or the high-durability catalyst layer according to claim 9.

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