Dynamic self-repairing type composite electrolyzed water diaphragm as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of hydrogen production through water electrolysis, and particularly discloses a dynamic self-repairing type composite water electrolysis diaphragm as well as a preparation method and application thereof. According to the diaphragm, PES-PBA is taken as a matrix, 4-carboxyphenylboronic acid is covalently grafted to a PES molecular chain through acylating chlorination reaction, and a dynamic B-O bonding interface is formed by the PES molecular chain and titanium dioxide with the surface modified by catechol groups; a titanium carbide nanosheet reinforced phase and a fractal hierarchical porous structure are combined, and a main channel and branch micropores which are vertically arranged are constructed by utilizing an ice template method. And a pH response type coupling agent and a self-repairing microcapsule are introduced, so that dynamic regulation and control of interface hydrophilicity and hydrophobicity and in-situ damage repairing are realized. According to the diaphragm, the ionic conduction efficiency, the gas barrier property and the environmental adaptability of the diaphragm are remarkably improved through bionic fractal pore channel design, dynamic bonding interface regulation and control and intelligent self-repairing function integration, and the diaphragm is suitable for an intermittent efficient hydrogen production system driven by renewable energy sources.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by electrolysis of water, and specifically relates to a dynamic self-repairing composite water electrolysis membrane and its preparation method and application, and especially relates to a self-repairing polyethersulfone (PES) / titanium oxide (TiO2) composite water electrolysis membrane based on a dynamic covalent bond interface and a bionic multi-level pore structure and its preparation method and application. Background Art

[0002] The alkaline water electrolysis diaphragm is a key component in the alkaline water electrolysis hydrogen production process. It separates the cathode and anode in the electrolyzer, preventing short circuits and avoiding mixing of gas products at the two electrodes. It also has high ionic conductivity, which is beneficial to promote the transfer of hydroxide ions from the cathode to the anode.

[0003] At present, alkaline water electrolysis membranes (such as Although the mechanical strength and hydrophilicity of the silane coupling agent series are improved by combining inorganic ceramic materials with polymers, the following problems still exist: 1) Insufficient interfacial bonding stability: Traditional silane coupling agents (such as KH-550) rely on physical adsorption or hydrogen bonding. Under long-term alkaline solution immersion (80°C / 6M KOH) and thermal cycling conditions, the inorganic particles and the polymer matrix are prone to interfacial delamination (shedding rate >15%), resulting in increased surface resistance (increase >30%) and uncontrolled hydrogen permeability (>0.05mL / min·cm 2 ). 2) Single pore structure: Homogeneous micropores (pore diameter 50-200nm) are difficult to balance the conflicting demands of low surface resistance (large pores are needed to reduce mass transfer resistance) and high gas resistance (small pores are needed to inhibit gas cross-permeation). The bubble point pressure of existing diaphragms is only 2.5-3.0bar, which cannot meet the design requirements of high-pressure differential electrolyzers. 3) Poor environmental adaptability: The frequent start-stop operations in the intermittent hydrogen production system cause the diaphragm to withstand periodic pH fluctuations (8-14) and temperature shocks (30-90℃). Traditional materials are prone to microcracks due to their lack of self-healing ability (crack growth rate>10μm / h), and their service life is less than 2000 hours. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present invention proposes a dynamic self-healing composite water electrolysis membrane, its preparation method, and its application. By integrating biomimetic fractal pore design, dynamic bonding interface control, and intelligent self-healing capabilities, this membrane significantly improves its ion conduction efficiency, gas barrier properties, and environmental adaptability, making it suitable for intermittent, efficient hydrogen production systems driven by renewable energy.

[0005] The inventive concept of the present invention is as follows: The present invention adopts dynamic covalent bond interface engineering: through the reversible BO bond of phenylboronic acid (PBA) and catechol (PDA), an adaptive interface is constructed to replace the traditional physical adsorption method. The bond strength can be increased by 2.3 times (from 0.8MPa to 2.7MPa), and the interface integrity retention rate after alkaline etching is greater than 95%. Bionic multi-level channel structure design: using ice template method combined with gradient heat treatment technology, fractal channels arranged perpendicular to the membrane surface are constructed (including main channels with a pore size of 200-500nm and branch micropores with a pore size of 50-100nm). The fractal dimension is optimized to 1.6-1.8, which can achieve low surface resistance (≤0.20Ω·cm 2 ) and high bubble point pressure (≥3.51bar). Integration of intelligent self-repairing functions: Introducing pH-responsive polymer microcapsules (such as polymer-coated silane coupling agent microcapsules) to trigger the rupture of microcapsules in the damaged area and release the repair agent silane coupling agent, which can achieve a repair efficiency of ≥92% within 24 hours, significantly extending the service life of the diaphragm. Therefore, the present invention provides a composite water electrolysis diaphragm with dynamic interface stability, bionic multi-stage mass transfer channels and in-situ self-repairing functions and a preparation method thereof, which solves the performance degradation problem of traditional diaphragms caused by interface aging, single pore structure and poor environmental adaptability, and can meet the core requirements of large-scale production of green hydrogen for high-efficiency and long-life diaphragms.

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing a composite water electrolysis membrane, comprising the following steps:

[0007] Polyethersulfone, a compound containing phenylboronic acid groups and a catalyst are added to an acyl chloride reagent to carry out an acyl chloride reaction to obtain phenylboronic acid-modified polyethersulfone, which is recorded as PES-PBA;

[0008] Nano-titanium dioxide was dispersed in an alcohol solution, and a buffer solution containing dopamine hydrochloride was added to form a catechol-modified layer on the surface of the nano-titanium dioxide, which was named TiO2@PDA.

[0009] Dissolving the PES-PBA in an organic solvent, adding the TiO2@PDA, titanium carbide nanosheets and pH-responsive microcapsules, and dispersing to obtain a slurry;

[0010] The slurry is applied to both sides of the support mesh, an ice template method is used to form ice crystal channels arranged perpendicular to the membrane surface, and a gradient heat treatment is performed to obtain a membrane-forming diaphragm;

[0011] The film-forming membrane is immersed in an alkaline solvent to trigger BO dynamic bonding between phenylboronic acid and catechol, and the alkaline solvent is removed to obtain the composite water electrolysis membrane.

[0012] In some embodiments of the present invention, the compound containing a boronic acid group is selected from at least one of 4-hydroxyphenylboronic acid (4-CPBA) and 3-hydroxyphenylboronic acid (3-CPBA), preferably 4-hydroxyphenylboronic acid.

[0013] In some embodiments of the present invention, the acyl chlorination reagent comprises thionyl chloride (SOCl2).

[0014] In some embodiments of the present invention, the molar ratio of the compound containing a boronic acid group to the acyl chloride reagent is 1:(1.2-1.8).

[0015] In some embodiments of the present invention, the catalyst comprises 4-dimethylaminopyridine (DMAP).

[0016] In some embodiments of the present invention, the amount of the catalyst is 1-2 wt% of the total mass of the reaction system.

[0017] In some embodiments of the present invention, the reaction conditions of the acyl chlorination reaction are: reaction at a temperature of 70-90° C. for 5-7 hours.

[0018] In some embodiments of the present invention, the molar ratio of the polyethersulfone to the compound containing phenylboronic acid groups is 1:(1.0-1.5), so as to ensure that 1.0-1.5 phenylboronic acid groups are grafted onto each PES chain segment.

[0019] In some embodiments of the present invention, the alcohol solution is selected from at least one of an ethanol solution, an ethylene glycol solution, and an isopropanol solution.

[0020] In some embodiments of the present invention, the buffer comprises Tris buffer.

[0021] In some embodiments of the present invention, the pH value of the buffer solution is 8-9, and the concentration of dopamine hydrochloride in the buffer solution is 1-3 mg / mL.

[0022] In some embodiments of the present invention, the particle size of the nano-titanium dioxide is 20-100 nm, for example, the particle size is 20 nm, 30 nm, 100 nm, etc.

[0023] In some embodiments of the present invention, the mass volume ratio of the nano-titanium dioxide to the buffer solution is 1:(40-60) mL.

[0024] In some embodiments of the present invention, in the TiO2@PDA, the catechol group density is ≥ 0.8 groups / nm 2 .

[0025] In some embodiments of the present invention, the organic solvent is selected from at least one of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO).

[0026] In some embodiments of the present invention, the pH-responsive microcapsules are polymer-coated silane coupling agent microcapsules, wherein the polymer is selected from at least one of urea-formaldehyde resin, polyurethane, and polyurea; preferably, urea-formaldehyde resin-coated KH-560 microcapsules, having a particle size of 2-5 μm and a shell thickness of 100-200 nm. Appropriately increasing the shell thickness facilitates delayed release. The pH-responsive microcapsules can be triggered to release by mechanical stress or pH changes.

[0027] In some embodiments of the present invention, the amount of the pH-responsive microcapsules added is 1-5 wt % of the total mass of the slurry.

[0028] In some embodiments of the present invention, the support mesh is a sulfonated polyphenylene sulfide (S-PPS) support mesh.

[0029] In some embodiments of the present invention, in the slurry, the mass ratio of PES-PBA, TiO2@PDA, and titanium carbide nanosheets is (8-12):(2-4):1.

[0030] In some embodiments of the present invention, the coating thickness of the slurry is 35-85 μm per side.

[0031] In some embodiments of the present invention, the process conditions of the ice template method are: vacuum freeze drying at a temperature of -30°C to -20°C for 12-36 hours, and the ice crystal growth direction is perpendicular to the membrane surface to form vertically arranged ice crystal channels.

[0032] In some embodiments of the present invention, the ice crystal channel includes a main channel and branch micropores, the pore size of the main channel is 200-500 nm, and the pore size of the branch micropores is 50-100 nm; the fractal dimension of the ice crystal channel is 1.6-1.8.

[0033] In some embodiments of the present invention, the gradient heat treatment process conditions include: annealing at 110-130°C for 0.5-1.5 hours, followed by hot pressing at 180-220°C and a pressure of 4-6 MPa for 5-15 minutes. This gradient heat treatment forms a dense gas barrier layer on the surface of the membrane, with a thickness of 5-10 μm.

[0034] In some embodiments of the present invention, the alkaline solution is an ethanol solution containing 1-3 mol / L NaOH or a NaOH solution containing 1-3 wt % glutaraldehyde.

[0035] In some embodiments of the present invention, the immersion time is 3-5 hours, triggering the formation of a dynamic BO bonding interface between the phenylboronic acid groups in PES-PBA and the catechol groups in TiO2@PDA. The density of the membrane after bonding is 0.8-1.2 bonds / nm. 2 .

[0036] In some embodiments of the present invention, the alkaline solvent is removed by placing the membrane in deionized water for 20-28 hours to completely remove the residual alkaline solvent.

[0037] In some embodiments of the present invention, after forming the composite water electrolysis membrane, the steps of repeating the above-mentioned ice template method to form a film-forming membrane and triggering BO dynamic bonding are further included to further improve the membrane performance.

[0038] The second aspect of the present invention provides a composite water electrolysis membrane, which is prepared by the above-mentioned composite water electrolysis membrane preparation method, wherein the surface resistance of the composite water electrolysis membrane is ≤0.20Ω·cm 2 , and after circulating 5000 times in 80℃ alkaline solution, the bubble point pressure is ≥3.51bar.

[0039] In some embodiments of the present invention, the composite water electrolysis membrane comprises a support mesh and functional layers attached to both sides of the support mesh, and the total thickness of the composite water electrolysis membrane is 150-250 μm.

[0040] The third aspect of the present invention provides the application of the composite water electrolysis membrane in the technical field of alkaline water electrolysis hydrogen production.

[0041] Compared with the prior art, the above technical solution of the present invention has at least the following technical effects or advantages:

[0042] (1) The present invention constructs an adaptive interface through the reversible BO bond of phenylboronic acid (PBA) and catechol (PDA), and adopts dynamic covalent bond interface engineering to replace the traditional physical adsorption method, so that the bond strength is greatly improved, and the interface can maintain good integrity after alkaline etching.

[0043] (2) The present invention adopts the ice template method combined with gradient heat treatment technology to design a bionic multi-level pore structure and construct vertically arranged fractal pores (including main channels with pore diameters of 200-500nm and branch micropores with pore diameters of 50-100nm). The fractal dimension is optimized to 1.6-1.8, achieving low surface resistance (≤0.20Ω·cm 2 ) and high bubble point pressure (≥3.51bar).

[0044] (3) The present invention introduces pH-responsive polymer microcapsules (such as polymer-coated silane coupling agent microcapsules) to trigger the rupture of microcapsules in the damaged area and release the repair agent in the core. By integrating intelligent self-repair functions, the present invention achieves a repair efficiency of ≥92% within 24 hours, significantly extending the service life of the diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a cross-sectional SEM image of the composite water electrolysis membrane prepared in Example 1 of the present invention;

[0046] Figure 2 The area resistance diagram of the composite water electrolysis membrane prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0047] Figure 3 Bubble point pressure diagram of the composite water electrolysis membrane prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0048] Figure 4 Graph showing the hydrogen permeability of the composite water electrolysis membranes prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0049] The present invention is described in detail below with reference to the examples to facilitate understanding of the present invention by those skilled in the art. It is necessary to point out that the examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned invention should still fall within the scope of protection of the present invention. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all process steps or preparation methods known to those skilled in the art.

[0050] Some of the raw materials used in the embodiments and comparative examples of the present invention are as follows:

[0051] Sulfonated polyphenylene sulfide (S-PPS) support mesh: Toray of Japan's Toray series, thickness 80 μm;

[0052] Titanium carbide nanosheets (Ti3C2T3): MXene-1001 from ACS Material LLC, USA, thickness <5nm.

[0053] Example 1

[0054] A method for preparing a dynamic self-repairing polyethersulfone / titanium oxide composite water electrolysis membrane comprises the following steps:

[0055] (1) Basic functional improvements:

[0056] 10 g of PES, 1.2 mol of 4-carboxyphenylboronic acid, and DMAP (1.5 wt% of the total mass of the reaction system) were added to thionyl chloride (the molar ratio of thionyl chloride to 4-carboxyphenylboronic acid was 1:1.5), and the reaction was carried out at 80° C. for 6 hours to obtain phenylboronic acid-modified polyethersulfone, which was designated as PES-PBA.

[0057] 1 g of 20 nm TiO2 was dispersed in ethanol solution, 50 mL of Tris buffer (pH = 8.5) containing dopamine (2 mg / mL) was added, and the mixture was stirred at room temperature for 24 hours to form a catechol modification layer on the surface of the nano-titanium dioxide, which was recorded as TiO2@PDA.

[0058] (2) Dynamic interface slurry preparation:

[0059] 10 g of PES-PBA, 3 g of TiO2@PDA, and 1 g of titanium carbide nanosheets were added to 100 g of NMP and ultrasonically dispersed for 2 h. Then, urea-formaldehyde resin-coated KH-560 microcapsules (particle size 2 μm, shell thickness 100 nm, added in an amount of 3 wt% of the total mass of the slurry) were added and stirred to obtain a slurry.

[0060] (3) Bionic multi-level pore structure forming:

[0061] The slurry is coated on both sides of an 80μm S-PPS support mesh with a coating thickness of 35-85μm on each side; an ice template method is used, the mesh is pre-frozen at -20°C and vacuum-dried for 24 hours to form ice crystal channels arranged perpendicular to the membrane surface; a gradient heat treatment is performed, first annealing at 120°C for 1 hour, and then hot pressing is performed at 200°C and a pressure of 5MPa for 10 minutes to form a dense gas barrier layer with a thickness of 5-10μm on the surface to obtain a film-forming diaphragm.

[0062] (4) Dynamic cross-linking and functional enhancement:

[0063] The membrane was immersed in 1 mol / L NaOH ethanol solution for 4 hours to trigger the BO dynamic bonding between phenylboronic acid and catechol. The density of the membrane after bonding was 1.0 bonds / nm 2 ; Then, the mixture was placed in deionized water for 24 hours to completely remove the residual solvent and obtain a composite water electrolysis membrane with a total thickness of 150-250 μm.

[0064] Figure 1 This is a cross-sectional SEM image of the composite water electrolysis membrane prepared in Example 1. Figure 1As can be seen in the figure, the membrane contains main channels and branch micropores. The pore size of the main channels is 200-500nm (SEM image statistical mean), and the pore size of the branch micropores is 50-100nm (BET measurement). Furthermore, pore distribution analysis using ImageJ software calculated the separation dimension to be 1.6-1.8.

[0065] Example 2

[0066] A method for preparing a dynamic self-repairing polyethersulfone / titanium oxide composite water electrolysis membrane comprises the following steps:

[0067] (1) Basic functional improvements:

[0068] 10 g of PES, 1.5 mol of 4-carboxyphenylboronic acid, and DMAP (1.5 wt% of the total mass of the reaction system) were added to thionyl chloride (the molar ratio of thionyl chloride to 4-carboxyphenylboronic acid was 1:1.5), and the reaction was carried out at 80° C. for 8 hours to obtain phenylboronic acid-modified polyethersulfone, which was designated as PES-PBA.

[0069] 1 g of 30 nm TiO2 was dispersed in ethanol solution, 50 mL of Tris buffer (pH = 8.5) containing dopamine (2 mg / mL) was added, and the mixture was stirred at room temperature for 36 hours to form a catechol modification layer on the surface of the nano-titanium dioxide, which was recorded as TiO2@PDA.

[0070] (2) Dynamic interface slurry preparation:

[0071] 10 g of PES-PBA, 4 g of TiO2@PDA, and 1 g of titanium carbide nanosheets were added to 100 g of NMP and ultrasonically dispersed for 3 hours. Then, urea-formaldehyde resin-coated KH-560 microcapsules (particle size 2 μm, shell thickness 100 nm, added in an amount of 3 wt% of the total mass of the slurry) were added and stirred to obtain a slurry.

[0072] (3) Bionic multi-level pore structure forming:

[0073] The slurry was coated on both sides of an 80μm S-PPS support mesh with a coating thickness of 35-85μm on each side; an ice template method was used, the mesh was pre-frozen at -30°C and vacuum dried for 36 hours to form ice crystal channels arranged perpendicular to the membrane surface; a gradient heat treatment was performed, first annealing at 120°C for 1 hour, and then hot pressing was performed at 200°C and a pressure of 5MPa for 10 minutes to form a dense gas barrier layer with a thickness of 5-10μm on the surface to obtain a film-forming diaphragm.

[0074] (4) Dynamic cross-linking and functional enhancement:

[0075] The membrane was immersed in 1.5 mol / L NaOH ethanol solution for 6 hours to trigger the BO dynamic bonding between phenylboronic acid and catechol. The density of the membrane after bonding was 1.1 bonds / nm 2 ; Then, the mixture was placed in deionized water for 24 hours to completely remove the residual solvent and obtain a composite water electrolysis membrane with a total thickness of 150-250 μm.

[0076] Example 3

[0077] A method for preparing a dynamic self-repairing polyethersulfone / titanium oxide composite water electrolysis membrane comprises the following steps:

[0078] (1) Basic functional improvements:

[0079] 15 g of PES, 1.2 mol of 4-carboxyphenylboronic acid, and DMAP (1.5 wt% of the total mass of the reaction system) were added to thionyl chloride (the molar ratio of thionyl chloride to 4-carboxyphenylboronic acid was 1:1.5), and the reaction was carried out at 80° C. for 6 hours to obtain phenylboronic acid-modified polyethersulfone, which was designated as PES-PBA.

[0080] 1 g of 20 nm TiO2 was dispersed in ethanol solution, 50 mL of Tris buffer (pH = 8.5) containing dopamine (2 mg / mL) was added, and the mixture was stirred at room temperature for 24 hours to form a catechol modification layer on the surface of the nano-titanium dioxide, which was recorded as TiO2@PDA.

[0081] (2) Dynamic interface slurry preparation:

[0082] 10 g of PES-PBA, 3 g of TiO2@PDA, and 1 g of titanium carbide nanosheets were added to 100 g of NMP and ultrasonically dispersed for 2 h. Then, urea-formaldehyde resin-coated KH-560 microcapsules (particle size 5 μm, shell thickness 200 nm, added in an amount of 5 wt% of the total mass of the slurry) were added and stirred to obtain a slurry.

[0083] (3) Bionic multi-level pore structure forming:

[0084] The slurry was coated on both sides of the 80μm S-PPS support mesh with a coating thickness of 35-85μm on each side; the ice template method was used, pre-frozen at -25°C, and vacuum dried for 30 hours to form ice crystal channels arranged perpendicular to the membrane surface; a gradient heat treatment was performed, first annealing at 120°C for 1 hour, and then hot pressing was performed at 220°C and 5MPa pressure for 10 minutes to form a dense gas barrier layer with a thickness of 5-10μm on the surface to obtain a film-forming diaphragm.

[0085] (4) Dynamic cross-linking and functional enhancement:

[0086] The membrane was immersed in a NaOH solution containing 2 wt% glutaraldehyde for 4 hours to trigger the BO dynamic bonding of phenylboronic acid and catechol and the comprehensive double crosslinking of aldehyde groups. The density of the membrane after bonding was 1.0 bonds / nm 2 ; Then, the mixture was placed in deionized water for 24 hours to completely remove the residual solvent and obtain a composite water electrolysis membrane with a total thickness of 150-250 μm.

[0087] Example 4

[0088] A method for preparing a dynamic self-repairing polyethersulfone / titanium oxide composite water electrolysis membrane comprises the following steps:

[0089] (1) Basic functional improvements:

[0090] 10 g of PES, 1.2 mol of 4-carboxyphenylboronic acid, and DMAP (1.5 wt% of the total mass of the reaction system) were added to thionyl chloride (the molar ratio of thionyl chloride to 4-carboxyphenylboronic acid was 1:1.5), and the reaction was carried out at 80° C. for 6 hours to obtain phenylboronic acid-modified polyethersulfone, which was designated as PES-PBA.

[0091] 1 g of 20 nm TiO2 was dispersed in ethanol solution, 50 mL of Tris buffer (pH = 8.5) containing dopamine (2 mg / mL) was added, and the mixture was stirred at room temperature for 24 hours to form a catechol modification layer on the surface of the nano-titanium dioxide, which was recorded as TiO2@PDA.

[0092] (2) Dynamic interface slurry preparation:

[0093] 10 g PES-PBA, 3 g TiO2@PDA, and 2 g (or 0.5 g) titanium carbide nanosheets were added to 100 g NMP and ultrasonically dispersed for 2 h. Then, urea-formaldehyde resin-coated KH-560 microcapsules (particle size 2 μm, shell thickness 100 nm, added in an amount of 3 wt% of the total mass of the slurry) were added and stirred to obtain slurry 1 (2 g titanium carbide nanosheets) and slurry 2 (0.5 g titanium carbide nanosheets), respectively.

[0094] (3) Bionic multi-level pore structure forming:

[0095] The slurry 1 was coated on both sides of the 80μm S-PPS support mesh, pre-frozen at -20°C using the ice template method, and vacuum-dried for 24 hours to form vertically arranged ice crystal channels; a gradient heat treatment was performed, first annealing at 120°C for 1 hour, and then hot pressing was performed at 200°C and a pressure of 5MPa for 10 minutes to form a dense gas barrier layer with a thickness of 5-10μm on the surface, thereby improving the electron shielding capability and obtaining the first film-forming diaphragm.

[0096] (4) Dynamic cross-linking and functional enhancement:

[0097] The first film-forming membrane was immersed in a 1 mol / L NaOH ethanol solution for 4 hours to trigger the BO dynamic bonding between phenylboronic acid and catechol; then, the membrane was allowed to stand in deionized water for 24 hours to completely remove the residual solvent, thereby obtaining the first composite water electrolysis membrane.

[0098] (5) Secondary pre-freezing and gradient bonding

[0099] Slurry 2 was applied to the surface of the first composite water electrolysis membrane, pre-frozen at -20°C, vacuum-dried for 24 hours, and pre-frozen again to form a porous layer. The membrane was then immersed in a 0.5 mol / L NaOH ethanol solution for 4 hours to trigger the BO dynamic gradient bonding between phenylboronic acid and catechol. The membrane was then allowed to stand in deionized water for 24 hours to completely remove any residual solvent, resulting in a composite water electrolysis membrane with a total thickness of 150-250 μm.

[0100] Comparative Example 1

[0101] The difference between Comparative Example 1 and Example 1 is only that step (4) is different, and Comparative Example 1 does not perform dynamic crosslinking and functional enhancement.

[0102] Step (4) of comparative document 1 is: placing the film-forming membrane in deionized water for 24 hours to completely remove the residual solvent and prepare a composite water electrolysis membrane.

[0103] Comparative Example 2

[0104] The difference between Comparative Example 2 and Example 1 is only that step (2) is different. In Comparative Example 2, no urea-formaldehyde resin-coated KH-560 microcapsules are added to the slurry.

[0105] Step (2) of Comparative Example 2 is: adding 10 g of PES-PBA, 3 g of TiO2@PDA, and 1 g of titanium carbide nanosheets to 100 g of NMP, and ultrasonically dispersing them for 2 hours to obtain a slurry.

[0106] Comparative Example 3

[0107] The difference between Comparative Example 3 and Example 1 is only that step (3) is different. Comparative Example 3 uses the traditional solvent volatilization method instead of the ice template method of Example 1.

[0108] Step (3) of Comparative Example 3 is: coating the slurry on both sides of the 80 μm S-PPS support mesh and vacuum drying at room temperature for 36 hours; performing gradient heat treatment, first annealing at 120°C for 1 hour, and then hot pressing at 200°C and a pressure of 5 MPa for 10 minutes to obtain a film-forming diaphragm.

[0109] Performance Testing

[0110] The surface resistance (Arearesistance), hydrogen permeability (Hydrogen permeability), self-repair efficiency and bubble point pressure (Bubblepoint pressure) of the composite water electrolysis membrane prepared in Examples 1-4 and Comparative Examples 1-3 were tested. The test results are shown in Table 1 and Figure 2-4 shown.

[0111] Surface resistivity was tested using the four-probe method (ASTM F1529-1997) at 80°C and 6 mol / L KOH solution. Hydrogen permeability was tested according to GB / T 20042.3-2009 at a pressure differential of 2 bar and a test area of 1 cm. 2 Self-healing efficiency was tested according to ISO 19252:2016, using an optical microscope to measure the area ratio of a 1mm scratch before and after repair. Bubble point pressure was measured after 5,000 cycles in an 80°C alkaline solution.

[0112] Table 1:

[0113]

[0114] As shown in Table 1, the composite water electrolysis membranes prepared in Examples 1-4 all have low surface resistance (≤0.20Ω·cm 2 ) and high bubble point pressure (≥3.51bar); and has good self-repair ability. After 24 hours of repair of a 1mm scratch, the self-repair efficiency is ≥92%; and under a pressure difference of 2bar, the hydrogen permeability is ≤6.42mL / min·cm 2 .

[0115] Compared with Example 1, Comparative Examples 1-3 have significantly lower performance in all aspects of the diaphragm than in Example 1 due to the lack of BO dynamic bonding between phenylboric acid and catechol, the absence of urea-formaldehyde resin-coated KH-560 microcapsules, and the failure to form vertically arranged ice crystal channels.

[0116] For those skilled in the art to which the present invention belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present invention, without having to resort to creative work. Therefore, based on the disclosure of the present invention, simple improvements made by those skilled in the art to the present invention should be within the scope of protection of the present invention. The above embodiments are preferred embodiments of the present invention, and all processes similar to the present invention and equivalent changes made should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a composite water electrolysis membrane, characterized in that: The following steps are involved: Polyethersulfone, a compound containing phenylboronic acid groups and a catalyst are added to an acyl chloride reagent to carry out an acyl chloride reaction to obtain phenylboronic acid-modified polyethersulfone, which is recorded as PES-PBA; Nano-titanium dioxide was dispersed in an alcohol solution, and a buffer solution containing dopamine hydrochloride was added to form a catechol-modified layer on the surface of the nano-titanium dioxide, which was named TiO2@PDA. The PES-PBA is dissolved in an organic solvent, and the TiO2@PDA, titanium carbide nanosheets and pH-responsive microcapsules are added and dispersed to obtain a slurry; The slurry is applied to both sides of the support mesh, an ice template method is used to form ice crystal channels arranged perpendicular to the membrane surface, and a gradient heat treatment is performed to obtain a membrane-forming diaphragm; The film-forming membrane is immersed in an alkaline solvent to trigger BO dynamic bonding between phenylboronic acid and catechol, and the alkaline solvent is removed to obtain the composite water electrolysis membrane.

2. The method for preparing a composite water electrolysis membrane according to claim 1, wherein: The compound containing a boronic acid group is selected from at least one of 4-hydroxyphenylboronic acid and 3-hydroxyphenylboronic acid; and / or, the acyl chloride reagent comprises thionyl chloride; And / or, the catalyst comprises 4-dimethylaminopyridine.

3. The method for preparing the composite water electrolysis membrane according to claim 1 or 2, wherein: The molar ratio of the polyethersulfone to the compound containing phenylboronic acid groups is 1:(1.0-1.5).

4. The method for preparing a composite water electrolysis membrane according to claim 1, wherein: The alcohol solution is selected from at least one of ethanol solution, ethylene glycol solution, and isopropanol solution; And / or, the buffer comprises Tris buffer; And / or, the organic solvent is selected from at least one of N-methylpyrrolidone, dimethylacetamide, and dimethyl sulfoxide; And / or, the pH-responsive microcapsules are polymer-coated silane coupling agent microcapsules, and the polymer is selected from at least one of urea-formaldehyde resin, polyurethane, and polyurea; And / or, the support network is a sulfonated polyphenylene sulfide support network.

5. The method for preparing the composite water electrolysis membrane according to claim 1 or 4, characterized in that: In the slurry, the mass ratio of PES-PBA, TiO2@PDA, and titanium carbide nanosheets is (8-12): (2-4): 1; And / or, the amount of the pH-responsive microcapsules added is 1-5 wt % of the total mass of the slurry.

6. The method for preparing a composite water electrolysis membrane according to claim 1, wherein: The process conditions of the ice template method are: vacuum freeze drying at a temperature of -30°C to -20°C for 12-36 hours; And / or, the ice crystal channel includes a main channel and branch micropores, the pore size of the main channel is 200-500 nm, and the pore size of the branch micropores is 50-100 nm; the fractal dimension of the ice crystal channel is 1.6-1.

8.

7. The method for preparing a composite water electrolysis membrane according to claim 1, wherein: The gradient heat treatment process conditions are: first annealing at 110-130° C. for 0.5-1.5 hours, and then hot pressing at 180-220° C. and a pressure of 4-6 MPa for 5-15 minutes.

8. The method for preparing a composite water electrolysis membrane according to claim 1, wherein: The alkaline solution is an ethanol solution containing 1-3 mol / L NaOH or a NaOH solution containing 1-3 wt% glutaraldehyde; And / or, after the BO dynamic bonding, the density of the diaphragm is 0.8-1.2bonds / nm 2 .

9. A composite water electrolysis membrane, characterized in that: The composite water electrolysis membrane is prepared by the preparation method of any one of claims 1 to 8, wherein the surface resistance of the composite water electrolysis membrane is ≤ 0.20Ω·cm 2 , and after circulating 5000 times in 80℃ alkaline solution, the bubble point pressure is ≥3.51bar.

10. Application of the composite water electrolysis membrane according to claim 9 in the technical field of alkaline water electrolysis hydrogen production.

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