Integrated membrane electrode assembly and preparation method thereof

Abstract

The invention discloses an integrated membrane electrode assembly and a preparation method, the integrated membrane electrode assembly comprises a porous catalyst layer, a diaphragm hole layer and a diaphragm skin layer which are connected in sequence, and a support grid is arranged in the diaphragm hole layer; the average thickness of the porous catalyst layer is 50-150 [mu] m, the average pore size of the porous catalyst layer is 1-2 [mu] m, the porosity is 35-50%, and the porous catalyst layer is an adhesive film material containing transition metal powder; the diaphragm hole layer and the diaphragm skin layer are both made of a nano-ceramic-containing adhesive film material; wherein the adhesive film material is a high-molecular polymer containing a film-forming additive. The integrated membrane electrode assembly is prepared through one-time forming of the membrane electrode structure, the integrity of the membrane pore channel structure is guaranteed, meanwhile, the prepared catalyst layer has a porous structure, the preparation efficiency of the alkaline water electrolysis membrane electrode assembly is improved, and the electrolysis performance of the alkaline water electrolysis membrane electrode assembly applied to the water electrolysis process is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of alkaline water electrolysis, and particularly relates to an integrated membrane electrode assembly and a preparation method thereof. Background Technique

[0002] The alkaline water electrolysis hydrogen production technology generates oxygen and hydrogen by electrolyzing KOH solution. In order to avoid the intermixing of oxygen and hydrogen during the water electrolysis process, improve the hydrogen purity and the safety of electrolysis, a diaphragm is placed in the alkaline water electrolyzer. An ideal diaphragm material should have good ionic conductivity, low resistivity, high gas barrier property, thin thickness, high mechanical strength, and long-term durability in high-temperature and high-concentration alkaline electrolytes.

[0003] The research and development of diaphragm materials has gone through iterative processes such as asbestos diaphragms, polyphenylene sulfide (PPS) diaphragms, and composite diaphragms. Asbestos diaphragms are traditional diaphragms for alkaline electrolyzers, with advantages such as high strength, corrosion resistance, high temperature resistance, and good hydrophilicity, but they have been phased out due to toxicity. PPS diaphragms have excellent heat resistance and high mechanical strength, but their ionic conductivity is relatively low. Composite diaphragms have been widely promoted due to their high strength, corrosion resistance, high ionic conductivity, and high gas production purity. Moreover, composite diaphragms are easy to be compounded with catalysts to form membrane electrode assemblies for alkaline water electrolysis.

[0004] For example, Patent CN118390110A discloses a diaphragm and a preparation method for an alkaline hydrolysis tank. The diaphragm is a porous metal oxide structure with a porosity of 30-38% and an average pore diameter of 1-5 μm. The diaphragm thickness is 300-350 μm, and the metal oxide structure contains at least one of zirconia and titanium dioxide. In the preparation method, an inorganic skeleton is first formed and sintered from a mixture containing inorganic raw materials, and an organic filler penetrates into the inorganic skeleton, and then through phase transformation, the diaphragm for the alkaline hydrolysis tank is obtained. The diaphragm for the alkaline hydrolysis tank provided by this solution has high wet tensile strength, uses an organic filler to condition the pore structure, has excellent gas barrier property, and has high erosion resistance.

[0005] The current process of forming a membrane electrode assembly by compounding with a catalyst usually involves first preparing a composite separator or directly performing hot pressing, spraying, ion sputtering, or electrodeposition of the catalyst on a commercial composite separator. For example, Patent CN116240569A provides a composite separator electrode for alkaline water electrolysis, its preparation method, and application. The composite separator electrode includes a catalyst layer A, a skin layer, a finger-shaped porous layer, a three-dimensional porous layer, and a catalyst layer B connected in sequence; among them, the three-dimensional porous layer contains a support. This solution first obtains a separator for alkaline water electrolysis with an ultra-high bubble point through a special heterogeneous structure design of the skin layer, finger-shaped porous layer, and three-dimensional porous layer. Moreover, this separator has an extremely low surface resistance, hydrophilicity, and ultra-fast wettability. Then, the water electrolysis catalyst is directly coupled with the separator to prepare a separator electrode for the alkaline water electrolysis process, which can effectively reduce the interfacial resistance generated by the separation of the catalyst layer and the separator in the traditional alkaline water electrolysis process, thereby effectively improving the current density during the water electrolysis process.

[0006] As in the above prior art, when coupling the water electrolysis catalyst with the separator, hot pressing or spraying processes are usually used. Among them, when preparing by the hot pressing process, high pressure may cause the separator to perforate, and may also damage the pore structure of the separator and the catalytic layer structure; when preparing by the spraying process, the bonding strength between the catalyst layer and the separator is insufficient, and under the conditions of electrolyte scouring, bubble impact, and frequent start-stop during the water electrolysis process, coating peeling is likely to occur, and the dense catalytic layer formed by traditional spraying also hinders the gas-liquid mass transfer during water electrolysis.

[0007] Therefore, it is an urgent problem for those skilled in the art to develop a convenient, low-cost, and high-efficiency preparation method to prepare a composite separator electrode assembly with a high bubble point, high catalytic activity, and high electrochemical performance. Summary of the Invention

[0008] Aiming at the defects existing in the above prior art, the present invention provides an integrated membrane electrode assembly and a preparation method. The integrated membrane electrode assembly includes a porous catalytic layer, a separator pore layer, and a separator skin layer connected in sequence. A support grid is arranged in the separator pore layer; the average thickness of the porous catalytic layer is 50 - 150 μm, the average pore diameter of the porous catalytic layer is 1 - 2 μm, the porosity is 35 - 50%, and the porous catalytic layer is a bonding film material containing transition metal elements; both the separator pore layer and the separator skin layer are bonding film materials containing nano-ceramics; among them, the bonding film material is a polymer containing a film-forming additive.

[0009] The present invention adopts an integrated preparation process for the membrane electrode assembly. The preparation method is simple and efficient. Through a one-time forming of the membrane electrode structure, an integrated membrane electrode assembly is prepared, which not only ensures the integrity of the separator pore structure but also makes the prepared catalytic layer have a porous structure, improving the preparation efficiency of the alkaline water electrolysis membrane electrode assembly and the electrolysis performance during the water electrolysis process.

[0010] In a first aspect, the present invention provides an integrated membrane electrode assembly, specifically including: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence, with a support grid disposed in the diaphragm pore layer;

[0011] The average thickness of the porous catalytic layer is 50 - 150 μm, the average pore diameter of the porous catalytic layer is 1 - 2 μm, the porosity is 35 - 50%, and the porous catalytic layer is a binder film material containing transition metal powder;

[0012] Both the diaphragm pore layer and the diaphragm skin layer are binder film materials containing nano-ceramics;

[0013] Among them, the binder film material is a polymer containing a film-forming additive.

[0014] Further, the average thickness of the porous catalytic layer is 70 - 120 μm.

[0015] Further, the transition metal powder is nickel-aluminum alloy powder.

[0016] Further, the metal elements of the transition metal powder include at least one of nickel, cobalt, iron, manganese, and molybdenum;

[0017] Further, the ceramic includes at least one of zirconia, titania, and silica.

[0018] Further, the film-forming additive includes at least one of polyvinylpyrrolidone, polyethylene glycol, chitosan, and polyethyleneimine; the polymer includes at least one of polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, and polytetrafluoroethylene.

[0019] Further, the support grid is one of polyphenylene sulfide and polypropylene, the mesh number of the support grid is 30 - 200, the thickness of the support grid is not greater than the average thickness of the finger-like pore layer, and the thickness of the support grid is 110 - 260 μm.

[0020] Further, the diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence, the sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0021] The average pore diameter of the sponge pore layer is 3 - 8 μm, the porosity is 50 - 60%, and the average thickness of the sponge pore layer is 10 - 40 μm;

[0022] The porosity of the finger-like pore layer is 50 - 80%, and the average thickness of the finger-like pore layer is 110 - 360 μm.

[0023] Further, the average thickness of the diaphragm skin layer is 3 - 10 μm.

[0024] Second aspect, the present invention also provides a method for preparing the above integrated membrane electrode assembly, specifically including the following steps:

[0025] S1: Mix a polymer, a film-forming additive, and an organic solvent to prepare a binder slurry. The polymer is at least one of polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, and polytetrafluoroethylene. The film-forming additive is at least one of polyvinylpyrrolidone, polyethylene glycol, chitosan, and polyethyleneimine. The organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. The mass ratio of the polymer, the film-forming additive, and the organic solvent is 1:(0.05 - 0.5):(2.5 - 6);

[0026] S2: Add a catalyst to the binder slurry to prepare a catalyst slurry, and add a nano ceramic agent to the binder slurry to prepare a separator slurry;

[0027] S3: Knife-coat the catalyst slurry onto a substrate. After the catalyst slurry is dried, an initial catalytic layer is obtained, where the temperature of the substrate tabletop is set at 50 - 80°C;

[0028] S4: Adjust the temperature of the substrate tabletop to 30 - 60°C, cover the initial catalytic layer with a support grid, knife-coat the separator slurry, and after pre-evaporation for 2 - 8 min, form an initial separator layer;

[0029] S5: Immerse the substrate covered with the initial separator layer in deionized water for phase inversion to form a porous catalytic layer, a separator pore layer, and a separator skin layer, thereby preparing an integrated membrane electrode assembly.

[0030] Further, in step S1, after mixing the polymer, the film-forming additive, and the organic solvent, it further includes:

[0031] Stir in an environment of 25 - 80°C with a stirrer at a rotation speed of 250 - 2000 rpm for at least 24 h.

[0032] Further, in step S2, the catalyst is a transition metal powder particle, the maximum particle size of the catalyst is not greater than 100 μm, and the mass ratio of the polymer to the catalyst in the catalyst slurry is 1:(20 - 50);

[0033] The nano ceramic agent is a nano ceramic powder particle, the average particle size of the nano ceramic agent is 20 - 100 nm, and the mass ratio of the polymer to the nano ceramic agent in the separator slurry is 1:(3.5 - 8).

[0034] Further, in step S2, the average particle size of the catalyst is 10 - 30 μm, and the mass ratio of the polymer to the catalyst in the catalyst slurry is 1:(20 - 35);

[0035] Further, in step S2, after adding a catalyst to the binder slurry, the following steps are also included:

[0036] Stirring with a stirrer at a rotation speed of 250 - 2000 rpm for not less than 12 h in an environment of 25 - 80°C;

[0037] In step S2, after adding a nano-ceramic agent to the binder slurry, the following steps are also included:

[0038] Stirring with a stirrer at a rotation speed of 250 - 2000 rpm for not less than 24 h in an environment of 30 - 50°C, and then defoaming in a defoamer for 5 - 30 min.

[0039] Further, in step S3, the height of the doctor blade during scraping is 50 - 150 μm; in step S4, the height of the doctor blade during scraping is not less than the sum of the thicknesses of the initial catalytic layer and the support grid, and the height of the doctor blade during scraping is 180 - 1000 μm.

[0040] Further, in step S3, the height of the doctor blade during scraping is 70 - 120 μm.

[0041] Further, in step S4, the thickness of the support grid is 110 - 260 μm, and the mesh number is 30 - 200.

[0042] Further, in step S5, the time for phase inversion by immersion in deionized water is not less than 24 h, and multiple water replacements are carried out during phase inversion, with the time interval between each water replacement not exceeding 8 h.

[0043] An integrated membrane electrode assembly and a preparation method provided by the present invention at least include the following

[0044] Beneficial effects:

[0045] (1) The present invention adopts an integrated preparation process for the membrane electrode assembly. The preparation method is simple and efficient. Through one-time molding of the membrane electrode structure, an integrated membrane electrode assembly is prepared, which not only ensures the integrity of the diaphragm pore structure but also enables the prepared catalytic layer to have a porous structure, improving the preparation efficiency of the alkaline water electrolysis membrane electrode assembly and the electrolysis performance during the water electrolysis process.

[0046] (2) The integrated membrane electrode assembly provided by the present invention has a porous catalytic layer with better performance. This porous catalytic layer has more reaction sites, and gas is more easily discharged, effectively reducing the hindrance of bubbles to the catalytic process.

[0047] (3) The preparation process of the integrated membrane electrode assembly provided by the present invention involves dissolution and re-solidification during the formation of the porous catalytic layer. That is, after the diaphragm slurry is scrape-coated on the initial catalytic layer, during the pre-evaporation process, the already dried initial catalytic layer gradually dissolves and returns to the wet coagulation state. Then, it is placed in water for phase inversion to form a porous catalytic layer. At this time, the porous catalytic layer is more tightly combined with the diaphragm pore layer, is not easily detached, and is integrally formed with the diaphragm pore layer and the diaphragm skin layer. Description of the Drawings

[0048] Figure 1 It is a schematic structural diagram of an integrated membrane electrode assembly provided by the present invention;

[0049] Figure 2 It is a cross-sectional scanning electron micrograph of an integrated membrane electrode assembly of a certain embodiment provided by the present invention.

[0050] Description of the reference numerals: 1 - porous catalytic layer, 2 - diaphragm pore layer, 21 - sponge pore layer, 22 - finger-shaped pore layer, 23 - support grid, 3 - diaphragm skin layer. Detailed Description of the Embodiment

[0051] In order to better understand the above technical solution, the following will describe the above technical solution in detail in conjunction with the drawings in the specification and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0052] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Multiple" generally includes at least two.

[0053] It should also be noted that the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a commodity or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such commodity or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.

[0054] The current process of forming a membrane electrode assembly by compounding with a catalyst usually involves first preparing a composite separator, or directly performing hot pressing, spraying, ion sputtering, or electrodeposition of the catalyst on a commercial composite separator. The above preparation processes are complex (among them, hot pressing and spraying also require the use of additional special equipment), and the catalytic coatings prepared by processes such as hot pressing and spraying have insufficient bonding strength with the composite separator substrate, which easily leads to the destruction of the composite separator structure. At the same time, the catalytic coatings formed by the above preparation processes generally present a dense morphology, which hinders the gas-liquid mass transfer during water electrolysis.

[0055] To overcome the above problems existing in the prior art, when forming the membrane electrode assembly, a suitable catalyst slurry and separator slurry are prepared, and based on the phase inversion method, the integrated membrane electrode assembly is prepared by a one-step method to form a separator pore layer and a porous catalytic layer with a complete pore structure, which not only improves the preparation efficiency and operability, but also prepares a membrane electrode assembly with excellent electrolysis performance.

[0056] In the first aspect, as Figure 1 shown, the present invention provides an integrated membrane electrode assembly, which specifically includes: a porous catalytic layer 1, a separator pore layer 2, and a separator skin layer 3 connected in sequence, and a support grid 23 is arranged in the separator pore layer 2;

[0057] The average thickness of the porous catalytic layer 1 is 50 - 150 μm, the average pore diameter of the porous catalytic layer 1 is 1 - 2 μm, the porosity is 35 - 50%, and the porous catalytic layer 1 is a binder film material containing transition metal powder;

[0058] Both the separator pore layer 2 and the separator skin layer 3 are binder film materials containing nano-ceramics;

[0059] Among them, the binder film material is a polymer containing a film-forming additive.

[0060] The porosity is the percentage of the volume of pores in the coating to the total volume of the entire coating.

[0061] In the integrated membrane electrode assembly provided by the present invention, the porous catalytic layer is coupled with the separator pore layer and the separator skin layer in sequence. The porous structure of the porous catalytic layer has more reaction sites, and the gas is more easily discharged, which can effectively reduce the hindrance of bubbles to the catalytic process. The porous catalytic layer with a thickness of 50 - 150 μm, a pore diameter of 1 - 2 μm, and a porosity of 35 - 50% can not only ensure the mechanical properties and durability of the membrane electrode assembly, but also reduce the surface resistance of the entire membrane electrode assembly, improve the current density during the water electrolysis process. At the same time, the porous catalytic layer also has good hydrophilicity.

[0062] In addition, the support grid in the membrane electrode assembly is used to enhance the strength of the membrane electrode assembly. The diaphragm pore layer and diaphragm skin layer formed by the binder film material containing nano-ceramics can achieve good gas barrier properties while not hindering ion transport. The porous catalytic layer formed by the binder film material containing transition metal powder can effectively promote hydrogen production and oxygen production during the electrolysis of water.

[0063] Preferably, the average thickness of the porous catalytic layer 1 is 70 - 120 μm.

[0064] Furthermore, the transition metal powder is nickel-aluminum alloy powder;

[0065] Furthermore, the metal elements of the transition metal powder include at least one of nickel, cobalt, iron, manganese, and molybdenum;

[0066] Furthermore, the ceramic includes at least one of zirconium dioxide, titanium dioxide, and silicon dioxide. That is, the nano-ceramic includes at least one of nano-zirconium dioxide powder, nano-titanium dioxide powder, and nano-silicon dioxide powder.

[0067] Furthermore, the support grid 23 is one of polyphenylene sulfide and polypropylene. The mesh number of the support grid 23 is 30 - 200. The thickness of the support grid is not greater than the average thickness of the finger-shaped pore layer, and the thickness of the support grid is 110 - 260 μm.

[0068] Furthermore, the film-forming additive includes at least one of polyvinylpyrrolidone, polyethylene glycol, chitosan, and polyethyleneimine; the high molecular polymer includes at least one of polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, and polytetrafluoroethylene.

[0069] Furthermore, the diaphragm pore layer 2 includes a sponge pore layer 21 and a finger-shaped pore layer 22 connected in sequence. The sponge pore layer 21 is connected to the porous catalytic layer 1, and the finger-shaped pore layer 22 is connected to the diaphragm skin layer 3;

[0070] The average pore diameter of the sponge pore layer 21 is 3 - 8 μm, the porosity is 50 - 60%, and the thickness of the sponge pore layer is 10 - 40 μm;

[0071] The porosity of the finger-shaped pore layer 22 is 50 - 80%, and the thickness of the finger-shaped pore layer 22 is 110 - 360 μm.

[0072] Furthermore, the thickness of the diaphragm skin layer 3 is 3 - 10 μm.

[0073] In a second aspect, the present invention also provides a method for preparing the above integrated membrane electrode assembly, which specifically includes the following steps:

[0074] S1: Mix a high molecular polymer, a film-forming additive, and an organic solvent to prepare a binder slurry. The high molecular polymer is at least one of polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, and polytetrafluoroethylene. The film-forming additive is at least one of polyvinylpyrrolidone, polyethylene glycol, chitosan, and polyethyleneimine. The organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. The mass ratio of the high molecular polymer, the film-forming additive, and the organic solvent is 1:(0.05 - 0.5):(2.5 - 6);

[0075] S2: Add a catalyst to the binder slurry to prepare a catalyst slurry, and add a nano-ceramic agent to the binder slurry to prepare a separator slurry;

[0076] S3: Knife-coat the catalyst slurry onto a substrate. After the catalyst slurry dries, an initial catalytic layer is obtained, where the temperature of the substrate tabletop is set at 50 - 80°C;

[0077] S4: Adjust the temperature of the substrate tabletop to 30 - 60°C, cover a support grid on the initial catalytic layer, knife-coat the separator slurry, and after pre-evaporating for 2 - 8 min, form an initial separator layer;

[0078] S5: Immerse the initial separator layer in deionized water for phase inversion to form a porous catalytic layer, a separator pore layer, and a separator skin layer, and prepare an integrated membrane electrode assembly.

[0079] In the preparation process of the integrated membrane electrode assembly provided by the present invention, both the separator slurry and the catalyst slurry are prepared based on the same binder slurry, so as to facilitate the one-step forming of the membrane electrode assembly during the phase inversion process.

[0080] The organic solvents selected for the binder slurry are all high-boiling polar solvents, which can effectively dissolve the binder and are also a prerequisite for realizing the dissolution and re-solidification process in the preparation of the porous catalytic layer.

[0081] During the dissolution and re-solidification process of the preparation of the porous catalytic layer, setting a reasonable temperature of the substrate tabletop can not only ensure that the initial catalytic layer has a basically formed structure, but also realize the mixing and blending with the initial separator layer during the knife-coating of the separator slurry and pre-evaporation, and finally form a porous catalytic layer and a separator pore layer with a tight combination.

[0082] Further, in step S1, after mixing the high molecular polymer, the film-forming additive, and the organic solvent, it further includes:

[0083] Stir with a stirrer at a rotation speed of 250 - 2000 rpm for not less than 24 h in an environment of 25 - 80°C.

[0084] Further, in step S2, the catalyst is transitional metal powder particles, the maximum particle size of the catalyst is not greater than 100 μm, and the mass ratio of the polymer in the catalyst slurry to the catalyst is 1:(20 - 50);

[0085] Further, in step S2, the average particle size of the catalyst is 10 - 30 μm, and the mass ratio of the polymer in the catalyst slurry to the catalyst is 1:(20 - 35);

[0086] The nano-ceramic agent is nano-ceramic powder particles, the average particle size of the nano-ceramic agent is 20 - 100 nm, and the mass ratio of the binder in the separator slurry to the nano-ceramic agent is 1:(3.5 - 8).

[0087] Setting the particle size of the catalyst and the mass ratio of the polymer in the catalyst slurry within a reasonable range can form a catalyst slurry with better fluidity, ensure the formation of a porous catalytic layer that is continuous and meets the requirements for porosity and catalytic performance, and the overall structure of the porous catalyst is more stable. At the same time, each pore inside the porous catalytic layer has pore uniformity, pore shape regularity, and pore wall integrity.

[0088] Further, in step S2, after adding the catalyst to the binder slurry, it further includes:

[0089] Stirring with a stirrer at a rotation speed of 250 - 2000 rpm for not less than 12 h in an environment of 25 - 80 °C;

[0090] In step S2, after adding the nano-ceramic agent to the binder slurry, it further includes:

[0091] Stirring with a stirrer at a rotation speed of 250 - 2000 rpm for not less than 24 h in an environment of 30 - 50 °C, and then defoaming in a defoamer for 5 - 30 min.

[0092] Further, the substrate is one of a glass plate, a quartz plate, and a stainless steel plate.

[0093] Further, in step S3, the height of the doctor blade during scraping is 50 - 150 μm; in step S4, the height of the doctor blade during scraping is not less than the sum of the thicknesses of the initial catalytic layer and the support grid, and the height of the doctor blade during scraping is 180 - 1000 μm.

[0094] Further, in step S3, the height of the doctor blade during scraping is 70 - 120 μm.

[0095] The setting of the height of the doctor blade during scraping in step S3 is related to the thickness of the porous catalytic layer. Setting the height of the doctor blade to be almost the same as the average thickness of the porous catalytic layer can enable the catalyst slurry to form a porous catalytic layer that meets the thickness requirements during the evolution process from the initial catalytic layer to the porous catalytic layer.

[0096] In step S4, the setting of the doctor blade height during knife coating is related to the thickness and components of the porous catalytic layer, the diaphragm pore layer, and the diaphragm skin layer. Due to the small particle size of the nano-ceramic agent in the diaphragm slurry and the shrinkage phenomenon during the phase inversion process in step S5, generally, the doctor blade height during knife coating needs to be greater than the sum of the thicknesses of the porous catalytic layer, the diaphragm pore layer, and the diaphragm skin layer.

[0097] Furthermore, in step S4, the thickness of the support grid is 110 - 260 μm, and the mesh number is 30 - 200.

[0098] Furthermore, in step S5, the time for phase inversion by immersing in deionized water is not less than 24 h, and multiple water changes are carried out during phase inversion, with the time interval between each water change not exceeding 8 h.

[0099] Example 1:

[0100] In Example 1, the specific steps for preparing the integrated membrane electrode assembly are as follows:

[0101] S1: Add polysulfone and polyvinylpyrrolidone to N-methylpyrrolidone, mix, and place in a constant temperature water bath environment at 40 °C. Use an electric stirrer to stir at a speed of 400 rpm for 24 h until the polysulfone is completely dissolved to prepare an adhesive slurry; among them, the mass ratio of polysulfone, polyvinylpyrrolidone, and N-methylpyrrolidone is 1:0.13:4.

[0102] S2: Take a part of the adhesive slurry, add nickel-aluminum alloy powder to the adhesive slurry, and use an electric stirrer to stir at a speed of 1000 rpm for 12 h in a constant temperature water bath environment at 25 °C to prepare a catalyst slurry; among them, the average particle size of the nickel-aluminum alloy powder is about 20 μm, the molar ratio of nickel to aluminum in the nickel-aluminum alloy powder is 1:1, and the mass ratio of polysulfone to nickel-aluminum alloy powder in the catalyst slurry is 1:30.

[0103] Take a part of the adhesive slurry, add nano-zirconia powder to the adhesive slurry, and use an electric stirrer to stir at a speed of 600 rpm for 24 h in a constant temperature water bath environment at 40 °C. After stirring, put it into a vacuum degassing machine for degassing for 10 min to prepare a diaphragm slurry; among them, the average particle size of the nano-zirconia powder is 20 nm, and the mass ratio of polysulfone to zirconia powder in the diaphragm slurry is 1:5.66.

[0104] S3: Set the temperature of the glass plate tabletop to 60 °C, knife coat the catalyst slurry onto the glass plate, set the doctor blade height to 100 μm, and the knife coating speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalytic layer is obtained.

[0105] S4: Adjust the temperature of the glass plate tabletop to 40°C. Place polyphenylene sulfide with a thickness of 260 μm and a mesh number of 40 as a support grid on the initial catalytic layer, and then scrape the diaphragm slurry onto the surface of the support grid. Set the height of the scraper to 750 μm and the scraping speed to 25 mm / s. At this time, the diaphragm slurry completely covers the support grid. After pre-evaporation for 5 min, an initial diaphragm layer is formed.

[0106] S5: Immerse the glass plate covered with the initial diaphragm layer completely in deionized water for 24 h of phase inversion. Replace the deionized water every 8 h during the phase inversion process. After the phase inversion is completed, the initial diaphragm layer solidifies into a film, and a porous catalytic layer is loaded on the side attached to the glass plate to prepare an integrated membrane electrode assembly.

[0107] When storing the membrane electrode assembly, first, immerse the membrane electrode assembly in an aqueous solution containing 30 wt.% KOH and 10 wt.% sodium potassium tartrate. The temperature of the aqueous solution is 80°C, and the immersion time is 24 h; then, take out the membrane electrode assembly and store it in deionized water.

[0108] When preparing to use the membrane electrode assembly, the integrated membrane electrode assembly prepared in S5 or stored in deionized water can be first placed in an 80°C oven and dried for 30 min.

[0109] As Figure 2 shown, the integrated membrane electrode assembly prepared in this embodiment includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence. A support grid is arranged in the diaphragm pore layer;

[0110] The average thickness of the porous catalytic layer is about 100 μm, the average pore diameter of the porous catalytic layer is about 1.2 μm, and the porosity is about 45%;

[0111] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0112] The average pore diameter of the sponge pore layer is about 5 μm, the porosity is about 55%, and the average thickness of the sponge pore layer is about 20 μm;

[0113] The porosity of the finger-like pore layer is about 60%, and the average thickness of the finger-like pore layer is about 350 μm;

[0114] The average thickness of the diaphragm skin layer is about 8 μm.

[0115] [[ID=3D]] Example 2:

[0116] On the basis of Example 1, Example 2 adjusts the following parameters.

[0117] Compared with the preparation process of Example 1, in step S2 of this example:

[0118] S2: Take a part of the binder slurry, add nickel-aluminum alloy powder to the binder slurry, and in a constant temperature water bath environment at 25 °C, use an electric stirrer to stir at a speed of 1000 rpm for 12 h to prepare a catalyst slurry; wherein, the average particle size of the nickel-aluminum alloy powder is about 20 μm, the molar ratio of nickel to aluminum in the nickel-aluminum alloy powder is 1:1, and the mass ratio of polysulfone to nickel-aluminum alloy powder in the catalyst slurry is 1:20.

[0119] The integrated membrane electrode assembly prepared in this example includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence, and a support grid is arranged in the diaphragm pore layer;

[0120] The average thickness of the porous catalytic layer is about 100 μm, the average pore size of the porous catalytic layer is about 1.9 μm, and the porosity is about 48%;

[0121] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence, the sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0122] The average pore size of the sponge pore layer is about 3.6 μm, the porosity is about 60%, and the average thickness of the sponge pore layer is about 28 μm;

[0123] The porosity of the finger-like pore layer is about 72%, and the average thickness of the finger-like pore layer is about 343 μm;

[0124] The average thickness of the diaphragm skin layer is about �.5 μm.

[0125] Example 3:

[0126] On the basis of Example 1, Example 3 adjusts the following parameters.

[0127] Compared with the preparation process of Example 1, in step S2 of this example:

[0128] S2: Take a part of the binder slurry, add nickel-aluminum alloy powder to the binder slurry, and in a constant temperature water bath environment at 25 °C, use an electric stirrer to stir at a speed of 1000 rpm for 12 h to prepare a catalyst slurry; wherein, the average particle size of the nickel-aluminum alloy powder is 30 μm, the molar ratio of nickel to aluminum in the nickel-aluminum alloy powder is 1:1, and the mass ratio of polysulfone to nickel-aluminum alloy powder in the catalyst slurry is 1:30.

[0129] The integrated membrane electrode assembly prepared in this example includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence, and a support grid is arranged in the diaphragm pore layer;

[0130] The average thickness of the porous catalyst layer is about 100 μm, the average pore diameter of the porous catalyst layer is about 1.8 μm, and the porosity is about 50%;

[0131] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalyst layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0132] The average pore diameter of the sponge pore layer is about 3.5 μm, the porosity is about 53%, and the average thickness of the sponge pore layer is about 35 μm;

[0133] [[ID= 9]]The porosity of the finger-like pore layer is about 76%, and the average thickness of the finger-like pore layer is about 337 μm;

[0134] The average thickness of the diaphragm skin layer is about 7 μm.

[0135] Example 4:

[0136] On the basis of Example 1, Example 4 adjusts the following parameters.

[0137] Compared with the preparation process of Example 1, in step S3 of this example:

[0138] S3: Set the temperature of the glass plate tabletop to 60 °C, scrape the catalyst slurry onto the glass plate, set the height of the scraper to 50 μm, and the scraping speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalyst layer is obtained.

[0139] The integrated membrane electrode assembly prepared in this example includes: a porous catalyst layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence. A support grid is arranged in the diaphragm pore layer;

[0140] The average thickness of the porous catalyst layer is about 50 μm, the average pore diameter of the porous catalyst layer is about 1.6 μm, and the porosity is about 42%;

[0141] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalyst layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0142] The average pore diameter of the sponge pore layer is about 4.2 μm, the porosity is about 57%, and the average thickness of the sponge pore layer is about 39 μm;

[0143] The porosity of the finger-like pore layer is about 65%, and the average thickness of the finger-like pore layer is about 351 μm;

[0144] The average thickness of the diaphragm skin layer is about 5 μm.

[0145] Example 5:

[0146] Based on Example 1, Example 5 adjusts the following parameters.

[0147] Compared with the preparation process of Example 1, in steps S3 and S4 of this example:

[0148] S3: Set the temperature of the glass plate tabletop to 60 °C, scrape the catalyst slurry onto the glass plate, set the height of the scraper to 50 μm, and the scraping speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalytic layer is obtained.

[0149] S4: Adjust the temperature of the glass plate tabletop to 40 °C, place a polyphenylene sulfide with a thickness of 110 μm and a mesh number of 150 as a support grid on the initial catalytic layer, and then scrape the diaphragm slurry onto the surface of the support grid. Set the height of the scraper to 400 μm and the scraping speed to 25 mm / s. At this time, the diaphragm slurry completely covers the support grid. After pre-evaporation for 5 minutes, an initial diaphragm layer is formed.

[0150] The integrated membrane electrode assembly prepared in this example includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence. A support grid is arranged in the diaphragm pore layer;

[0151] The average thickness of the porous catalytic layer is about 50 μm, the average pore diameter of the porous catalytic layer is about 1.6 μm, and the porosity is about 45%;

[0152] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0153] The average pore diameter of the sponge pore layer is about 3.1 μm, the porosity is about 53%, and the average thickness of the sponge pore layer is about 18 μm;

[0154] The porosity of the finger-like pore layer is about 57%, and the average thickness of the finger-like pore layer is about 138 μm;

[0155] The average thickness of the diaphragm skin layer is about 3 μm.

[0156] Example 6:

[0157] Based on Example 1, Example 6 adjusts the following parameters.

[0158] Compared with the preparation process of Example 1, in steps S3 and S4 of this example:

[0159] S3: Set the temperature of the glass plate tabletop to 50 °C, scrape the catalyst slurry onto the glass plate, set the height of the scraper to 50 μm, and the scraping speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalytic layer is obtained.

[0160] S4: Maintain the temperature of the glass plate table at 50 °C. Place polyphenylene sulfide with a thickness of 110 μm and a mesh count of 150 on the initial catalytic layer as a support grid. Then scrape the diaphragm slurry onto the surface of the support grid. Set the height of the scraper to 400 μm and the scraping speed to 25 mm / s. At this time, the diaphragm slurry completely covers the support grid. After pre-evaporating for 5 min, an initial diaphragm layer is formed.

[0161] In the integrated membrane electrode assembly prepared in this embodiment, it includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence. A support grid is arranged in the diaphragm pore layer;

[0162] The average thickness of the porous catalytic layer is about 100 μm, the average pore diameter of the porous catalytic layer is about 1.4 μm, and the porosity is about 40%;

[0163] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0164] The average pore diameter of the sponge pore layer is about 4.2 μm, the porosity is about 52%, and the average thickness of the sponge pore layer is about 39 μm;

[0165] The porosity of the finger-like pore layer is about 52%, and the average thickness of the finger-like pore layer is about 331 μm;

[0166] The average thickness of the diaphragm skin layer is about 5 μm.

[0167] Comparative Example 1:

[0168] On the basis of Example 1, Comparative Example 1 adjusts the following parameters.

[0169] Compared with the preparation process of Example 1, in steps S3, S4, and S5 of this comparative example:

[0170] S3: Set the temperature of the glass plate table to 60 °C. Scrape the catalyst slurry onto the glass plate. Set the height of the scraper to 100 μm and the scraping speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalytic layer is obtained. Immerse the glass plate covering the initial catalytic layer completely in deionized water for 24 h of phase inversion. Replace the deionized water every 8 h during the phase inversion process. After the phase inversion is completed, the initial catalytic layer solidifies into a film. Place the film in an 80 °C oven and dry it for 30 min to obtain the catalytic layer.

[0171] S4: Set the temperature of the glass plate tabletop to 40 °C. Place polyphenylene sulfide with a thickness of 260 μm and a mesh number of 40 as the support grid on the initial catalyst layer, and then scrape the diaphragm slurry onto the surface of the support grid. Set the height of the scraper to 750 μm and the scraping speed to 25 mm / s. At this time, the diaphragm slurry completely covers the support grid. After pre-evaporation for 5 min, an initial diaphragm layer is formed. Immerse the glass plate covered with the initial diaphragm layer completely in deionized water for 24 h of phase inversion, and replace the deionized water every 8 h during the phase inversion process. After the phase inversion is completed, the initial diaphragm layer solidifies into a film to obtain the diaphragm layer.

[0172] S5: Bond the catalyst layer and the diaphragm layer and put them into a flat hot press. Place 0.1-μm-thick polytetrafluoroethylene films on both the contact surface between the catalyst layer and the hot press and the contact surface between the diaphragm layer and the hot press. Hot press at 120 °C and a pressure of 5 MPa for 5 min. After peeling off the polytetrafluoroethylene films, a hot-pressed membrane electrode assembly is obtained.

[0173] The membrane electrode assembly prepared in this comparative example includes: a catalyst layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence. A support grid is arranged in the diaphragm pore layer;

[0174] The thickness of the catalyst layer is about 100 μm;

[0175] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalyst layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0176] The average pore diameter of the sponge pore layer is about 3.6 μm, the porosity is about 55%, and the average thickness of the sponge pore layer is about 45 μm;

[0177] The porosity of the finger-like pore layer is about 60%, and the average thickness of the finger-like pore layer is about 413 μm;

[0178] The average thickness of the diaphragm skin layer is about 6 μm.

[0179] Comparative Example 2:

[0180] On the basis of Example 1, Comparative Example 2 adjusts the following parameters.

[0181] Compared with the preparation process of Example 1, in steps S1 and S2 of this comparative example:

[0182] S1: Add perfluorosulfonic acid (Nafion) to isopropanol, mix, and place it in a constant temperature water bath environment at 40 °C. Use an electric stirrer to stir at a speed of 400 rpm for 24 h to completely dissolve the perfluorosulfonic acid, and prepare the adhesive slurry a; wherein, the mass ratio of perfluorosulfonic acid to isopropanol is 1:4;

[0183] Polysulfone and polyvinylpyrrolidone were added to N-methylpyrrolidone, mixed, and placed in a constant temperature water bath environment at 40°C. An electric stirrer was used to stir at 400 rpm for 24 h to completely dissolve the polysulfone, and the adhesive slurry b was prepared; among them, the mass ratio of polysulfone, polyvinylpyrrolidone, and N-methylpyrrolidone was 1:0.13:4.

[0184] S2: Take a part of the adhesive slurry a, add nickel-aluminum alloy powder to the adhesive slurry a, and in a constant temperature water bath environment at 25°C, use an electric stirrer to stir at a speed of 1000 rpm for 12 h to prepare a catalyst slurry; among them, the average particle size of the nickel-aluminum alloy powder is 20 μm, the molar ratio of nickel to aluminum in the nickel-aluminum alloy powder is 1:1, and the mass ratio of polysulfone to nickel-aluminum alloy powder in the catalyst slurry is 1:30.

[0185] Take a part of the adhesive slurry b, add zirconia powder to the adhesive slurry b, and in a constant temperature water bath environment at 40°C, use an electric stirrer to stir at a speed of 600 rpm for 24 h. After stirring, put it into a vacuum degassing machine for degassing for 10 min to prepare a separator slurry; among them, the average particle size of the zirconia powder is 20 nm, and the mass ratio of polysulfone to zirconia powder in the separator slurry is 1:5.66.

[0186] The membrane electrode assembly prepared in this comparative example includes: a catalytic layer, a separator pore layer, and a separator skin layer connected in sequence, and a support grid is arranged in the separator pore layer;

[0187] The thickness of the catalytic layer is about 100 μm;

[0188] The separator pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the separator skin layer;

[0189] The average pore diameter of the sponge pore layer is about 3.9 μm, the porosity is about 56%, and the average thickness of the sponge pore layer is about 20 μm;

[0190] The porosity of the finger-like pore layer is about 60%, and the average thickness of the finger-like pore layer is about 345 μm;

[0191] The average thickness of the separator skin layer is about 5 μm.

[0192] Comparative Example 3:

[0193] On the basis of Example 1, Comparative Example 3 adjusted the following parameters.

[0194] Compared with the preparation process of Example 1, in step S2 of this comparative example:

[0195] S2: Take a part of the adhesive slurry, add nickel-aluminum alloy powder to the adhesive slurry, and use an electric stirrer to stir at a speed of 1000 rpm for 12 h in a constant temperature water bath environment at 25°C to prepare a catalyst slurry; among them, the average particle size of the nickel-aluminum alloy powder is 20 μm, the molar ratio of nickel to aluminum in the nickel-aluminum alloy powder is 1:1, and the mass ratio of polysulfone to nickel-aluminum alloy powder in the catalyst slurry is 1:60.

[0196] The integrated membrane electrode assembly prepared in this comparative example includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence, and a support grid is arranged in the diaphragm pore layer;

[0197] The average thickness of the porous catalytic layer is about 100 μm, the average pore size of the porous catalytic layer is about 0.8 μm, and the porosity is about 28%;

[0198] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0199] The average pore size of the sponge pore layer is about 5.1 μm, the porosity is about 56%, and the average thickness of the sponge pore layer is about 27 μm;

[0200] The porosity of the finger-like pore layer is about 48%, and the average thickness of the finger-like pore layer is about 341 μm;

[0201] The average thickness of the diaphragm skin layer is about 3 μm.

[0202] Comparative Example 4:

[0203] On the basis of Example 1, Comparative Example 4 adjusts the following parameters.

[0204] Compared with the preparation process of Example 1, in step S3 of this comparative example:

[0205] S3: Set the temperature of the glass plate tabletop to 90°C, scrape the catalyst slurry onto the glass plate, set the height of the scraper to 100 μm, and the scraping speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalytic layer is obtained.

[0206] The integrated membrane electrode assembly prepared in this comparative example includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm skin layer connected in sequence, and a support grid is arranged in the diaphragm pore layer;

[0207] The average thickness of the porous catalytic layer is about 100 μm, the average pore size of the porous catalytic layer is about 0.7 μm, and the porosity is about 75%;

[0208] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm skin layer;

[0209] The average pore diameter of the sponge pore layer is about 4.2 μm, the porosity is about 41%, and the average thickness of the sponge pore layer is about 18 μm;

[0210] The porosity of the finger-like pore layer is about 46%, and the average thickness of the finger-like pore layer is about 346 μm;

[0211] The average thickness of the diaphragm cortex is about 4 μm.

[0212] Comparative Example 5:

[0213] On the basis of Example 1, Comparative Example 5 adjusts the following parameters.

[0214] Compared with the preparation process of Example 1, in step S3 of this comparative example:

[0215] S3: Set the temperature of the glass plate tabletop to 60 °C, scrape the catalyst slurry onto the glass plate, set the height of the scraper to 200 μm, and the scraping speed to 25 mm / s. After the catalyst slurry is completely dried, an initial catalytic layer is obtained.

[0216] The integrated membrane electrode assembly prepared in this example includes: a porous catalytic layer, a diaphragm pore layer, and a diaphragm cortex connected in sequence. A support grid is arranged in the diaphragm pore layer;

[0217] The average thickness of the porous catalytic layer is about 200 μm, the average pore diameter of the porous catalytic layer is about 5 μm, and the porosity is about 21%;

[0218] The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm cortex;

[0219] The average pore diameter of the sponge pore layer is about 4.7 μm, the porosity is about 42%, and the average thickness of the sponge pore layer is about 31 μm;

[0220] The porosity of the finger-like pore layer is about 50%, and the average thickness of the finger-like pore layer is about 338 μm;

[0221] The average thickness of the diaphragm cortex is about 5 μm.

[0222] Performance Test:

[0223] Electrolytic water voltage test: Cut the membrane electrode assemblies of Examples 1-6 and Comparative Examples 1-5 into samples with a size of 4×4 cm, and assemble the samples into an electrolytic water test cell. During the test, use a 30 wt.% KOH solution, the solution temperature is 80 °C, and start the electrolysis process with a current of 0.5 A / cm

[0219] ,

[0217] , ,

[0218] , ,

[0221] ,

[0222] ,

[0220] , , Performance Test: , ,

[0223] , , , 2 , and record the electrolytic water voltage after running for 24 h.

[0224] Water absorption time test of the catalytic layer: The membrane electrode assemblies of Examples 1-6 and Comparative Examples 1-5 were cut into samples of 2×2 cm in size. Using a micro automatic liquid discharging device, 10 μL of liquid droplets were dropped onto the surface of the porous catalytic layer (or catalytic layer) of the sample, and a high-speed camera was used to record the time from the liquid droplet dropping onto the porous catalytic layer (or catalytic layer) to the liquid droplet being completely absorbed by the surface of the porous catalytic layer (or catalytic layer) of the membrane electrode assembly.

[0225] Table 1 Performance test data table of Examples 1-6 and Comparative Examples 1-5

[0226] Sample Electrolysis Voltage (V) Water Absorption Time (s) Example 1 1.65 5.35 Example 2 1.72 7.41 Example 3 1.7 7.07 Example 4 1.73 7.36 Example 5 1.66 5.31 Example 6 1.69 5.87 Comparative Example 1 1.77 10.78 Comparative Example 2 1.76 22.37 Comparative Example 3 1.81 9.64 Comparative Example 4 1.82 10.72 Comparative Example 5 1.79 9.61

[0227] In Comparative Example 1, the catalytic layer and the separator layer were respectively prepared by phase inversion, and then the membrane electrode assembly was assembled by laminating and hot pressing. The catalyst slurry in Comparative Example 1 could not achieve the evolution from the initial catalytic layer to the porous catalytic layer, and finally only a dense catalytic layer could be formed.

[0228] In Comparative Example 2, the binder slurries used for preparing the catalyst slurry and the separator slurry were different. Among them, the boiling point of the organic solvent isopropyl alcohol in the binder slurry a used for the catalyst slurry was relatively low, and phase inversion could not occur after dissolving the binder Nafion, and the evolution from the initial catalytic layer to the porous catalytic layer could not be achieved either. Finally, only a dense catalytic layer could be formed.

[0229] In Comparative Example 3, an excessive amount of catalyst (i.e., nickel-aluminum alloy powder) was added during the preparation of the catalyst slurry, resulting in poor fluidity of the catalyst slurry. During drying and phase inversion, the particles were closely packed, forming a lower porosity and smaller pore size.

[0230] In Comparative Example 4, the temperature of the substrate tabletop was relatively high during step S3, and the drying process of the catalyst slurry was fast and uneven, which was not conducive to the scraping process. The uniformity of the coating was poor, and the average pore size of the finally formed porous catalytic layer was too low and the porosity was too high, resulting in poor structural stability.

[0231] In Comparative Example 5, a higher blade height was set in step S3, and a porous catalytic layer with a relatively large average thickness was also formed. However, the average pore size of the porous catalytic layer was too large and the porosity was too low, and the stability of the porous catalytic layer was poor.

[0232] It can be seen from the performance test data that the electrolysis voltages of the membrane electrode assemblies of Examples 1-6 are all less than 1.75 V, and the electrolysis voltages of the membrane electrode assemblies of Comparative Examples 1-5 are all greater than 1.75 V.

[0233] In addition, the water absorption time of the porous catalytic layers in Examples 1-6 is less than 7.5 s, the water absorption time of the porous catalytic layers (or catalytic layers) in Comparative Examples 1-5 is greater than 9.5 s, and the water absorption time of the catalytic layer in Comparative Example 2 even exceeds 20 s.

[0234] Thus, the water absorption performance of the porous catalytic layer of the membrane electrode assembly obtained in Examples 1-6 of the present invention is greatly improved, while the electrolysis voltage is reduced, and a composite diaphragm electrode assembly with a high bubble point, high catalytic activity, and high electrochemical performance is prepared.

[0235] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. An integrated membrane electrode assembly, characterized in that Specifically include: A porous catalytic layer, a diaphragm pore layer, and a diaphragm cortical layer connected in sequence, with a support grid arranged in the diaphragm pore layer; The average thickness of the porous catalytic layer is 50 - 150 μm, the average pore diameter of the porous catalytic layer is 1 - 2 μm, the porosity is 35 - 50%, and the porous catalytic layer is a binder film material containing transition metal powder; Both the diaphragm pore layer and the diaphragm cortical layer are binder film materials containing nano-ceramics; Among them, the binder film material is a polymer containing a film-forming additive.

2. The integrated membrane electrode assembly according to claim 1, wherein The diaphragm pore layer includes a sponge pore layer and a finger-like pore layer connected in sequence. The sponge pore layer is connected to the porous catalytic layer, and the finger-like pore layer is connected to the diaphragm cortical layer; The average pore diameter of the sponge pore layer is 3 - 8 μm, the porosity is 50 - 60%, and the average thickness of the sponge pore layer is 10 - 40 μm; The porosity of the finger-like pore layer is 50 - 80%, and the average thickness of the finger-like pore layer is 110 - 360 μm.

3. The integrated membrane electrode assembly according to claim 1, wherein The average thickness of the diaphragm cortical layer is 3 - 10 μm.

4. A method for preparing the integrated membrane electrode assembly as described in any one of claims 1-3, characterized in that, Specifically include the following steps: S1: Mix a polymer, a film-forming additive, and an organic solvent to prepare a binder slurry. The polymer is at least one of polysulfone, polyethersulfone, polyphenylsulfone, polyetheretherketone, and polytetrafluoroethylene. The film-forming additive is at least one of polyvinylpyrrolidone, polyethylene glycol, chitosan, and polyethyleneimine. The organic solvent is at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. The mass ratio of the polymer, the film-forming additive, and the organic solvent is 1:(0.05 - 0.5):(2.5 - 6); S2: Add a catalyst to the binder slurry to prepare a catalyst slurry, and add a nano-ceramic agent to the binder slurry to prepare a diaphragm slurry; S3: Knife-coat the catalyst slurry onto a substrate. After the catalyst slurry dries, an initial catalytic layer is obtained, where the temperature of the substrate table is set to 50 - 80 °C; S4: Adjust the temperature of the substrate table to 30 - 60 °C, cover the support grid on the initial catalytic layer, knife-coat the diaphragm slurry, and pre-evaporate for 2 - 8 min to form an initial diaphragm layer; S5: Immerse the substrate covered with the initial diaphragm layer in deionized water for phase inversion to form a porous catalytic layer, a diaphragm pore layer, and a diaphragm cortical layer, and prepare an integrated membrane electrode assembly.

5. The method for preparing an integrated membrane electrode assembly according to claim 4, characterized in that, In step S1, after mixing the polymer, the film-forming additive, and the organic solvent, it further includes: Stirring in an environment of 25 - 80 °C with a stirrer at a rotation speed of 250 - 2000 rpm for no less than 24 h.

6. The method for preparing an integrated membrane electrode assembly according to claim 5, characterized in that In step S2, the catalyst is transition metal powder particles, the maximum particle size of the catalyst is not greater than 100 μm, and the mass ratio of the polymer to the catalyst in the catalyst slurry is 1:(20 - 50); The nano-ceramic agent is nano-ceramic powder particles, the average particle size of the nano-ceramic agent is 20 - 100 nm, and the mass ratio of the polymer to the nano-ceramic agent in the diaphragm slurry is 1:(3.5 - 8).

7. The method for preparing an integrated membrane electrode assembly according to claim 6, characterized in that, In step S2, after adding the catalyst to the binder slurry, it further includes: Stirring in an environment of 25 - 80 °C with a stirrer at a rotation speed of 250 - 2000 rpm for no less than 12 h; In step S2, after adding the nano-ceramic agent to the binder slurry, it further includes: Stirring in an environment of 30 - 50 °C with a stirrer at a rotation speed of 250 - 2000 rpm for not less than 24 h, and then defoaming in a defoamer for 5 - 30 min.

8. The method for preparing an integrated membrane electrode assembly according to claim 4, wherein, In step S3, the height of the doctor blade during scraping is 50 - 150 μm; in step S4, the height of the doctor blade during scraping is not less than the sum of the thicknesses of the initial catalytic layer and the support grid, and the height of the doctor blade during scraping is 180 - 1000 μm.

9. The method for preparing an integrated membrane electrode assembly according to claim 8, wherein In step S4, the thickness of the support grid is 110 - 260 μm, and the mesh number is 30 - 200.

10. The method for preparing an integrated membrane electrode assembly according to claim 9, wherein, In step S5, the time for phase inversion by immersing in deionized water is not less than 24 h, and multiple water replacements are carried out during phase inversion, and the time interval for each water replacement does not exceed 8 h.

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