A structured separator, its preparation method and use

Abstract

This invention belongs to the field of water electrolysis technology, specifically relating to a structured membrane, its preparation method, and its applications. The membrane includes: a membrane body, and a structural reinforcement layer bonded to the membrane body; the membrane body is either an alkaline water electrolysis composite membrane or an ion-solubilized membrane; when the membrane body is an alkaline water electrolysis composite membrane, it has a support layer with support lines; the structural reinforcement layer has structural reinforcement filaments, with the angle between the structural reinforcement filaments and the support lines greater than 0 degrees and less than 90 degrees; when the membrane body is an ion-solubilized membrane, the angle between the structural reinforcement filaments and the vertical direction is greater than 0 degrees and less than 45 degrees. This application involves the orderly deposition of structural reinforcement filaments on the membrane surface. The addition of these filaments has three advantages: it can improve the catalytic activity of the membrane, significantly increase the tensile strength of the membrane along the direction of the structural reinforcement filaments, and to a certain extent, regulate bubble behavior and reduce bubble accumulation.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis technology, specifically relating to a structured diaphragm, its preparation method, and its applications. Background Technology

[0002] With the goal of "carbon peaking and carbon neutrality," the development of clean energy has become a hot topic, and hydrogen energy, with its high calorific value and energy density, cleanliness, and pollution-free characteristics, has gradually become a research focus. Hydrogen production through water electrolysis has successfully stood out from numerous hydrogen production methods due to its advantages such as high safety, environmental friendliness, and high purity of produced hydrogen. Currently, the mainstream water electrolysis hydrogen production technologies include alkaline water electrolysis (ALK), proton exchange membrane water electrolysis (PEM), solid oxide electrolysis (SOEC), and anion exchange membrane water electrolysis (AEM). Among these, alkaline water electrolysis is currently the most mature and industrialized green hydrogen production technology. However, alkaline water electrolysis also faces some challenges in practical applications, including the performance of the diaphragm. The diaphragm is a key component of the alkaline electrolyzer, and its main function is to conduct OH-. - And to avoid mixing of the two polar products.

[0003] Alkaline electrolysis membranes have evolved through three generations: asbestos membranes, polyphenylene sulfide (PPS) membranes, and composite membranes. Asbestos membranes, the traditional type used in alkaline electrolyzers, offer advantages such as corrosion resistance, high temperature resistance, and good hydrophilicity, but suffer from poor gas barrier properties. PPS membranes possess excellent heat resistance, high mechanical strength, and superior electrical properties, but their poor hydrophilicity and large thickness typically result in high electrical resistance and poor gas permeability, leading to high energy consumption and easy hydrogen-oxygen cross-contamination.

[0004] The third-generation alkaline water electrolysis composite membrane is constructed by filling the gaps in a polyphenylene sulfide (PPS) support network with a casting agent, forming a sandwich-like structure. The casting agent is a mixed solution of zirconia inorganic nanoparticles and polymers, including but not limited to polysulfone (PSU), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK), dissolved in an organic solvent. The support network is a mesh structure formed by crisscrossing support lines. The addition of zirconia inorganic nanoparticles improves hydrophilicity. However, the third-generation composite membrane suffers from poor stability and low mechanical strength, both of which negatively impact the reaction process. Furthermore, during device assembly, the membrane is placed vertically, parallel to the direction of gravity. It is difficult for bubbles to detach from the membrane surface by gravity alone, leading to bubble accumulation and even gas crosstalk, resulting in slower current increase and higher ohmic resistance during the reaction.

[0005] Therefore, it is necessary to improve the existing composite membrane preparation technology to reduce the membrane resistance and improve the structural stability of the membrane, reduce the accumulation of bubbles on the membrane surface, and improve the efficiency of alkaline water electrolysis for hydrogen production. Summary of the Invention

[0006] A first aspect of the present invention provides a structured diaphragm, the diaphragm comprising: a diaphragm body, and a structural reinforcement layer bonded to the diaphragm body;

[0007] The membrane body is an alkaline water electrolysis composite membrane or an ion solvation membrane;

[0008] When the membrane body is an alkaline electrolysis composite membrane, the alkaline electrolysis composite membrane has a support layer, the support layer is located between two layers of casting agent, the support layer has support lines, the structural reinforcement layer has structural reinforcement filaments, and the included angle between the structural reinforcement filaments and the support lines is greater than 0 degrees and less than 90 degrees.

[0009] When the membrane body is an ion-solventized membrane, the angle between the structural reinforcing filament and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees.

[0010] The vertical direction refers to the direction parallel to gravity when the ion-solventized membrane is installed in the electrolytic cell.

[0011] Preferably, the angle between the structural reinforcing wire and the support wire is 45 degrees.

[0012] Preferably, the angle between the structural reinforcing wire and the vertical direction is 0 degrees.

[0013] Preferably, the alkaline water electrolysis composite membrane body has a three-layer structure, and the support layer is the middle layer.

[0014] Preferably, the support layer is a grid structure formed by the crisscrossing support lines.

[0015] Preferably, the structured membrane surface has structural reinforcing filaments, which can perform electrocatalysis during the reaction process.

[0016] Preferably, the structural reinforcing filament comprises several parallel-arranged metal fibers, alloy fibers, or inorganic oxide fibers. Metal fibers include, but are not limited to, nickel metal fibers and copper metal fibers; alloy fibers include, but are not limited to, stainless steel fibers; and inorganic oxide fibers include, but are not limited to, zirconium oxide and titanium oxide fibers. The catalytic activity gradually increases as the structural reinforcing filament progresses from inorganic oxide fibers such as zirconium oxide to stainless steel fibers, and then to catalysts sprayed onto the fiber surface or grown in situ.

[0017] The second aspect of this application provides a method for preparing the structured composite membrane described in the first aspect, the method comprising the following steps:

[0018] Step A: Dissolve the polymer material in an organic solvent and mix thoroughly to obtain a mixed solution with a mass fraction of less than 40%.

[0019] Step B: Arrange several structural reinforcing wires in an orderly manner on a flat plate, apply the mixed solution from Step A to the surface of the structural reinforcing wires, let it stand, and then attach the diaphragm body to the flat plate on which the structural reinforcing wires are laid. When attaching, adjust the angle between the structural reinforcing wires and the support line of the diaphragm body to be greater than 0 degrees and less than 90 degrees, or adjust the angle between the structural reinforcing wires and the vertical direction to be greater than or equal to 0 degrees and less than or equal to 45 degrees.

[0020] Step C: The above-mentioned diaphragm body and the polytetrafluoroethylene plate with several structural reinforcing filaments are hot-pressed together, and the several structural reinforcing filaments are bonded to the diaphragm body to obtain the structured diaphragm.

[0021] Preferably, the polymer material and organic solvent used in step A are the same as or similar to the casting agent components contained in the membrane body itself.

[0022] The polymer material is one or more of polysulfone (PSU), polyethersulfone, polyphenylene sulfide, polyetheretherketone, and polyetherketoneketone.

[0023] The organic solvent is one or more of N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, and N,N-dimethylformamide.

[0024] Preferably, the polymer material selected in this invention is polysulfone (PSU), and the organic solvent is N-methylpyrrolidone (NMP).

[0025] The third aspect of this application provides the use of the structured diaphragm described in the first aspect for improving the tensile strength of the diaphragm at various angles, particularly along the direction of the structural reinforcing filaments.

[0026] Preferably, the diaphragm is an alkaline water electrolysis composite diaphragm, and the angles include 0°, 45°, and 90°. These angles are based on the support lines in the alkaline water electrolysis composite diaphragm. The support line refers to any one of the support lines in the alkaline water electrolysis composite diaphragm. Generally, the support lines in the alkaline water electrolysis composite diaphragm are horizontal or vertical support lines.

[0027] The fourth aspect of this application provides the use of the structured membrane described in the first aspect for improving the hydrophilicity and conductivity of the membrane and increasing the catalytic activity per unit area of ​​the membrane.

[0028] Preferably, the diaphragm is an alkaline water electrolysis composite diaphragm.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The fourth aspect of this application provides the use of the structured membrane of the first aspect for improving the conductivity and hydrophilicity of the membrane and increasing the catalytic activity per unit area of ​​the membrane.

[0031] The fifth aspect of this application provides for the use of the structured diaphragm of the first aspect for regulating bubble behavior and reducing bubble accumulation.

[0032] The sixth aspect of this application provides an electrolytic cell, wherein a structured diaphragm is disposed within the electrolytic cell.

[0033] The diaphragm includes: a diaphragm body, and a structural reinforcement layer bonded to the diaphragm body;

[0034] The membrane body is an alkaline water electrolysis composite membrane or an ion solvation membrane;

[0035] Wherein, when the membrane body is an alkaline water electrolysis composite membrane:

[0036] The alkaline water electrolysis composite membrane body has a support layer, the support layer has support lines, the structural reinforcement layer has structural reinforcement wires, the angle between the structural reinforcement wires and the support lines is greater than 0 degrees and less than 90 degrees, and the angle between the structural reinforcement wires and the vertical direction is greater than 0 degrees and less than 45 degrees.

[0037] When the membrane body is an ion-solvated membrane:

[0038] The angle between the structural reinforcing wire and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees.

[0039] The vertical direction refers to the direction parallel to gravity when the diaphragm is installed inside the electrolytic cell.

[0040] Preferably, the angle between the reinforcing wire and the vertical direction is 0°.

[0041] The beneficial effects of this application are as follows:

[0042] This application utilizes a catalyst coating method similar to that used in membrane electrode assemblies (MEAs) to coat both sides of the membrane (CCM) to orderly lay structural reinforcing wires on the surface of the membrane body, such that the angle between the structural reinforcing wires of the structural reinforcing layer and the support lines in the membrane body is greater than 0 degrees and less than 90 degrees; and / or the angle between the structural reinforcing wires and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees.

[0043] The addition of structural reinforcing wires has the following advantages: it can significantly improve the tensile strength of the membrane along the direction of the reinforcing wires; it can improve the hydrophilicity and conductivity of the membrane; in addition, catalysts can be grown or sprayed on the structural reinforcing wires in situ, which can increase the active area and further improve the activity of water electrolysis; when installed in the electrolyzer, adjusting the angle between the structural reinforcing wires and the vertical direction to be greater than or equal to 0 degrees and less than or equal to 45 degrees can also regulate bubble behavior, reduce bubble accumulation, and thus increase the current speed of alkaline water electrolysis. Attached Figure Description

[0044] Figure 1 A schematic diagram of an alkaline water electrolysis composite diaphragm with structural reinforcing wires laid out.

[0045] Figure 2 The process flow diagrams are for Examples 1-6.

[0046] Figure 3 This is a photograph of the structured composite diaphragm obtained in Example 1.

[0047] Figure 4 The LSV curves of the structured membranes obtained in the examples and comparative examples are shown in the full water electrolysis device.

[0048] Figure 5 The stress-strain curves of the structured diaphragm obtained in the examples and comparative examples are shown along the direction of the structural reinforcing filament (45°).

[0049] Figure 6 This refers to the micro-motion path of the bubble along the direction of the structural reinforcing filament when it is parallel to the directions of gravity and buoyancy. Detailed Implementation

[0050] The present invention will be described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in the manual, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials used in the following embodiments and comparative examples are all commercially available.

[0051] The alkaline electrolysis composite diaphragm used below was purchased from Agfa, product model ZIRFON UTP 500. Polysulfone (PSU) was purchased from Solvay Chemicals, Inc. The organic solvent N-methylpyrrolidone (NMP) was purchased from Maclean Biotech, Inc.

[0052] This alkaline water electrolysis composite membrane is equivalent to the membrane body of this application. The alkaline water electrolysis composite membrane has a sandwich structure, with a middle support layer having support lines. The support layer is a grid structure formed by the support lines crisscrossing at 90-degree angles.

[0053] Example 1

[0054] A method for preparing a structured composite membrane:

[0055] (1) Preparation of polysulfone solution:

[0056] A certain mass of polysulfone (PSU) was dissolved in an N-methylpyrrolidone (NMP) solution, and stirred until all the PSU was dissolved. A polysulfone solution containing 10 wt% was obtained.

[0057] (2) Surface modification of alkaline electrolysis composite membrane:

[0058] Take stainless steel fibers with a diameter of 20 μm and arrange them evenly on a flat plate. Take the polysulfone solution prepared in step (1) and brush it evenly onto the surface of the structural reinforcing wire, then let it stand. Attach the alkaline electrolytic composite diaphragm to the side of the flat plate where the stainless steel fibers are laid, and adjust the stainless steel fibers to be at a 45° angle to the support lines inside the alkaline electrolytic composite diaphragm.

[0059] (3) Post-processing:

[0060] The above-mentioned alkaline electrolysis composite diaphragm and the plate with stainless steel fibers were placed together in a laminating machine and pressed at a pressure of 10 MPa for 1 minute. Then, the alkaline electrolysis composite diaphragm with stainless steel fibers bonded to it was separated from the PTFE plate. The resulting alkaline electrolysis composite diaphragm with stainless steel fibers bonded to it is the structured composite membrane.

[0061] Figure 3 The actual photograph of the structured composite membrane obtained in Example 1 shows that the structural reinforcing filaments are arranged in an orderly manner.

[0062] (4) Alkaline water electrolysis performance test:

[0063] The structured diaphragm prepared above was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0064] Example 2

[0065] (1) Preparation of polysulfone solution:

[0066] A certain mass of polysulfone (PSU) was dissolved in an N-methylpyrrolidone (NMP) solution, and stirred until all the PSU was dissolved. A polysulfone solution containing 5 wt% was obtained.

[0067] (2) Surface modification of alkaline electrolysis composite membrane:

[0068] Take 20 μm diameter stainless steel fibers and arrange them evenly on a plate. Take 0.2 mL of the polysulfone solution prepared in step (1) and brush it evenly onto the surface of the structural reinforcing filaments, then let it stand. Attach the alkaline electrolytic composite membrane to the side of the plate where the stainless steel fibers are laid, and adjust the stainless steel fibers to be at a 45° angle to the support lines within the alkaline electrolytic composite membrane.

[0069] (3) Post-processing:

[0070] At room temperature, the above-mentioned alkaline electrolysis composite diaphragm and a flat plate with stainless steel fibers were placed together in a film press and heated to 90°C, maintaining a pressure of 10 MPa for 1 minute. Then, the alkaline electrolysis composite diaphragm with stainless steel fibers bonded to it was separated from the flat plate. The resulting alkaline electrolysis composite diaphragm with stainless steel fibers bonded to it is the structured composite membrane.

[0071] (4) Alkaline water electrolysis performance test:

[0072] The structured diaphragm prepared above was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0073] Example 3

[0074] (1) Preparation of polysulfone solution:

[0075] A certain mass of polysulfone (PSU) was weighed and dissolved in an N-methylpyrrolidone (NMP) solution, and stirred until all the PSU was dissolved. A polysulfone solution containing 20 wt% was obtained.

[0076] (2) Surface modification of alkaline electrolysis composite membrane:

[0077] Take 20 μm diameter stainless steel fibers and arrange them evenly on a plate. Take 0.2 mL of the polysulfone solution prepared in step (1) and brush it evenly onto the surface of the structural reinforcing filaments, then let it stand. Attach the alkaline electrolytic composite membrane to the side of the plate where the stainless steel fibers are laid, and adjust the stainless steel fibers to be at a 45° angle to the support lines within the alkaline electrolytic composite membrane.

[0078] (3) Post-processing:

[0079] At room temperature, the alkaline electrolytic composite membrane and a flat plate coated with stainless steel fibers are placed together in a laminating machine and heated to 90°C, maintaining a pressure of 10 MPa for 1 minute. Then, the alkaline electrolytic composite membrane with stainless steel fibers bonded to it is separated from the flat plate. The resulting alkaline electrolytic composite membrane with stainless steel fibers bonded to it is the structured composite membrane.

[0080] (4) Alkaline water electrolysis performance test:

[0081] The structured diaphragm prepared above was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0082] Example 4:

[0083] (1) Preparation of polysulfone solution:

[0084] A certain mass of polysulfone (PSU) was dissolved in an N-methylpyrrolidone (NMP) solution and stirred until all the PSU was dissolved. A polysulfone solution containing 40 wt% was obtained.

[0085] (2) Surface modification of alkaline electrolysis composite membrane:

[0086] Take 20 μm diameter stainless steel fibers and arrange them evenly on a plate. Take 0.2 mL of the polysulfone solution prepared in step (1) and brush it evenly onto the surface of the structural reinforcing filaments, then let it stand. Attach the alkaline electrolytic composite membrane to the side of the plate where the stainless steel fibers are laid, and adjust the stainless steel fibers to be at a 45° angle to the support lines within the alkaline electrolytic composite membrane.

[0087] (3) Post-processing:

[0088] At room temperature, the alkaline electrolytic composite membrane and a flat plate coated with stainless steel fibers are placed together in a laminating machine and heated to 90°C, maintaining a pressure of 10 MPa for 1 minute. Then, the alkaline electrolytic composite membrane with stainless steel fibers is separated from the flat plate. The resulting alkaline electrolytic composite membrane with stainless steel fibers is the structured composite membrane.

[0089] (4) Alkaline water electrolysis performance test:

[0090] The structured diaphragm prepared above was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0091] Example 5:

[0092] The same operating steps as in Example 1 were adopted, except that stainless steel metal fibers were laid on both sides of the composite membrane.

[0093] Example 6: Zirconia fiber.

[0094] The same operating steps as in Example 1 were adopted, except that the stainless steel fiber was replaced with zirconium oxide fiber.

[0095] Example 7 - The angle between the structural reinforcing wire and the horizontal support line is close to 0 degrees.

[0096] The same operating steps as in Example 1 are adopted, the difference being that the angle between the structural reinforcing wire and the horizontal support line is adjusted to be close to 0 degrees, while in this example it is 5 degrees.

[0097] Example 8 - The angle between the structural reinforcing wire and the horizontal support line is close to 90 degrees.

[0098] The same operating steps as in Example 1 are adopted, the difference being that when the structural reinforcing wire is bonded to the diaphragm, the angle between the structural reinforcing wire and the horizontal support line is adjusted to be close to 90 degrees, while in this example it is 85 degrees.

[0099] Example 9 - The angle between the alkaline water electrolysis performance test and the vertical direction is 45 degrees.

[0100] The same operating steps as in Example 1 were adopted, except that when conducting alkaline water electrolysis performance testing, the angle between the structural reinforcing wire and the vertical direction was adjusted to 45 degrees.

[0101] Comparative Example 1

[0102] Take an alkaline water electrolysis composite membrane of the same area as in Example 1, without any treatment. Perform the test using the same operating procedures as in Example 1.

[0103] Comparative Example 2

[0104] (1) Surface modification of alkaline water electrolysis composite membrane:

[0105] Take an alkaline electrolysis composite membrane of the same area as in Example 1, and take 0.2 mL of the same 10 wt% polysulfone solution as in Example 1. Apply the solution evenly to the alkaline electrolysis composite membrane and dry it.

[0106] (2) Post-processing:

[0107] At room temperature, the above-mentioned alkaline water electrolysis composite diaphragm is placed into a film press and heated to 90°C, maintaining a pressure of 10 MPa for 1 minute.

[0108] (3) Alkaline water electrolysis performance test:

[0109] The above-mentioned diaphragm was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0110] Comparative Example 3

[0111] (1) Ordered arrangement of metal fibers on the membrane surface:

[0112] Take stainless steel fibers with a diameter of 20μm and a length of 4.5cm and arrange them evenly on a flat plate. Place one side of the alkaline electrolysis composite membrane against the side of the flat plate with the stainless steel fibers, adjusting the stainless steel fibers to form a 45° angle with the support lines within the alkaline electrolysis composite membrane. Leave the other side of the alkaline electrolysis membrane untreated.

[0113] (2) Post-processing:

[0114] At room temperature, the alkaline electrolysis composite membrane and a flat plate with stainless steel fibers were placed together in a laminating machine and heated to 90°C, maintaining a pressure of 10 MPa for 1 minute. Then, the alkaline electrolysis composite membrane with stainless steel fibers was separated from the flat plate. The resulting alkaline electrolysis composite membrane with stainless steel fibers is the structured composite membrane of Comparative Example 3.

[0115] (3) Alkaline water electrolysis performance test:

[0116] The structured diaphragm prepared above was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0117] Comparative Example 4 - without the addition of polysulfone.

[0118] (1) Preparation of polysulfone solution:

[0119] A certain mass of N-methylpyrrolidone (NMP) solution was taken to obtain a polysulfone solution containing 0 wt%.

[0120] (2) Surface modification of alkaline electrolysis composite membrane:

[0121] Take 20 μm diameter stainless steel fibers and arrange them evenly on a plate. Take 0.2 mL of the polysulfone solution prepared in step (1) and brush it evenly onto the surface of the structural reinforcing filaments, then let it stand. Attach the alkaline electrolytic composite membrane to the side of the plate where the stainless steel fibers are laid, and adjust the stainless steel fibers to be at a 45° angle to the support lines within the alkaline electrolytic composite membrane.

[0122] (3) Post-processing:

[0123] At room temperature, the alkaline electrolytic composite membrane and a flat plate with stainless steel fibers were placed together in a laminating machine and heated to 90°C, maintaining a pressure of 10 MPa for 1 minute. Then, the alkaline electrolytic composite membrane with stainless steel fibers was separated from the flat plate. The resulting alkaline electrolytic composite membrane with stainless steel fibers is the structured composite membrane of Comparative Example 4.

[0124] (4) Alkaline water electrolysis performance test:

[0125] The structured diaphragm prepared above was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, the angle between the structural reinforcing wire and the vertical direction needs to be adjusted to 0 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0126] Experimental and test results:

[0127] Alkaline water electrolysis performance test: The structured diaphragm prepared in the embodiments and comparative examples of the present invention was assembled with nickel foam for testing. Note that when assembling the electrolytic cell, it is necessary to adjust the angle between the structural reinforcing wire and the vertical direction to be greater than or equal to 0 degrees and less than or equal to 45 degrees. The vertical direction is the direction parallel to gravity and buoyancy when the diaphragm is installed in the electrolytic cell.

[0128] The test conditions were: temperature 80℃, and electrolyte using a 30wt% KOH solution. In actual water electrolysis tests, at the same voltage, a higher current density indicated better performance. The results are shown in Table 1 and... Figure 4 .

[0129] Table 1 and Figure 4 visible:

[0130] 1. All examples used patterned alkaline water electrolysis composite membranes with orderly arranged metal or inorganic fibers. The current densities of Examples 1-6 were significantly higher than those of the untreated membrane in Comparative Example 1. This indicates that the addition of metal or inorganic fibers effectively improved the performance of alkaline water electrolysis.

[0131] 2. The current density in Examples 1-6 was significantly higher than that in Comparative Example 2. This indicates that the method of simply brushing on the polysulfone solution without adding metal or inorganic fibers significantly increases the surface resistivity, leading to a decrease in performance.

[0132] 3. The current density in Examples 1-5 is significantly higher than that in Comparative Example 3. This indicates that without adding any polysulfone solution, hot pressing alone cannot tightly bond the metal fibers to the diaphragm, thus failing to achieve a zero-gap structure.

[0133] 4. The current densities in Examples 1-5 were significantly higher than those in Comparative Example 4. The solution in Comparative Example 3 did not contain polysulfone. This indicates that simply brushing on N-methylpyrrolidone (NMP) is insufficient to tightly bond the metal fibers to the membrane using only the polysulfone dissolved on the membrane surface itself, thus failing to achieve a zero-gap structure.

[0134] 5. The current density of Example 1 is significantly higher than that of Example 6, while the sheet resistance is lower. This indicates that adding metal fibers is more beneficial for reducing membrane resistance compared to inorganic fibers.

[0135] 6. In Example 4, the mixed solution contained 40 wt% polysulfone. The performance of Example 4 was also worse than that of Example 1, indicating that the addition of more polysulfone significantly increased the device resistance, thus covering the surface of the catalytic metal fiber, resulting in lower device performance than in Example 1.

[0136] 7. In Example 5, stainless steel fibers were laid on both sides of the composite diaphragm. The performance of Example 5 was also better than that of Example 1, indicating that laying metal fibers on both sides can further improve the electrolysis performance.

[0137] 8. The current density of Example 1 is significantly higher than that of Example 9, while the sheet resistance is lower. This indicates that when installed in the electrolytic cell, aligning the structural reinforcing wires parallel to the vertical direction is more conducive to the timely removal of bubbles from the membrane surface.

[0138] Table 1. Current density and device resistance during alkaline water electrolysis.

[0139]

[0140]

[0141] Mechanical performance testing:

[0142] The mechanical properties of the composite membranes prepared in the examples and comparative examples were characterized using a universal tensile testing machine. The stress-strain curves of the tested membranes were recorded, and the results are shown in Table 2 below. Figure 5 As shown in Table 2 below. Figure 5 This indicates that the addition of structural reinforcing fibers enhances the mechanical properties of the diaphragm and can significantly improve the tensile strength of the diaphragm along the direction of the structural reinforcing fibers.

[0143] Table 2 Tensile strength in different directions

[0144]

[0145]

[0146] The aforementioned angle is based on the horizontal support line in the alkaline water electrolysis composite membrane body, that is, the aforementioned angle is the angle between the structural reinforcing wire and the horizontal support line.

[0147] As can be seen from Table 2:

[0148] All examples employed patterned alkaline electrolytic membranes with ordered arrangements of metal or inorganic fibers. Examples 1-9 exhibited significantly better tensile strength at three angles than Comparative Examples 1-4. This indicates that the addition of metal fibers, alloy fibers, or inorganic fibers effectively improves the mechanical strength of the membrane. Example 1 showed significantly higher tensile strength at 45° than Examples 7 and 8, while its tensile strength at 0° and 90° was lower than that of Examples 7 and 8, demonstrating that the addition of structural reinforcing fibers significantly improves the mechanical strength along the direction of the reinforcing fibers.

[0149] In summary, this application discovers that by using a method similar to catalyst coating on both sides of the membrane (CCM) in a membrane electrode assembly (MEA), structural reinforcing filaments are orderly laid on the membrane surface, which has the following effects: it can improve the conductivity and hydrophilicity of the membrane; it can significantly improve the tensile strength of the membrane along the direction of the structural reinforcing filaments; it can allow the catalyst to be grown or sprayed on the structural reinforcing filaments in situ, thereby increasing the active area and further improving the water electrolysis activity; and it can effectively regulate the bubble behavior on the membrane surface to a certain extent, reducing bubble accumulation near the membrane and electrode.

[0150] Specifically, when assembling alkaline water electrolysis devices, the diaphragm is placed vertically, parallel to the directions of gravity and buoyancy, and the angle between the structural reinforcing wires and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees. For example... Figure 6 As shown, when the structural reinforcing wire is set at 0-45° (e.g., 0°) with the direction of gravity and buoyancy in this application, the bubbles generated on the diaphragm-electrode interface can move slightly along the structural reinforcing wire under the action of buoyancy. Therefore, it can regulate the bubble behavior to a certain extent, reduce bubble jamming and bubble accumulation, and at the same time reduce the cross-contamination of anode and cathode gases to a certain extent, thereby increasing the current speed of alkaline water electrolysis.

Claims

1. A structured diaphragm, characterized in that, The diaphragm includes: a diaphragm body, and a structural reinforcement layer bonded to the diaphragm body; The membrane body is an alkaline water electrolysis composite membrane or an ion solvation membrane; When the membrane body is an alkaline water electrolysis composite membrane, the alkaline water electrolysis composite membrane body has a support layer, the support layer has support lines, the structural reinforcement layer has structural reinforcement filaments, and the included angle between the structural reinforcement filaments and the support lines is greater than 0 degrees and less than 90 degrees. When the membrane body is an ion-solventized membrane, the angle between the structural reinforcing filament and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees. The vertical direction refers to the direction parallel to gravity when the ion-solventized membrane is installed in the electrolytic cell.

2. The alkaline water electrolysis composite diaphragm according to claim 1, characterized in that, The alkaline water electrolysis composite membrane body has a three-layer structure, and the support layer is the middle layer; The support layer is a grid structure formed by the crisscrossing support lines.

3. The structured diaphragm according to claim 1, characterized in that, The structural reinforcing filament comprises several parallel-arranged metal fibers, alloy fibers, or inorganic oxide fibers. Metal fibers include, but are not limited to, nickel and copper fibers; alloy fibers include, but are not limited to, stainless steel fibers; and inorganic oxide fibers include, but are not limited to, zirconium oxide and titanium oxide fibers. The catalytic activity gradually increases as the structural reinforcing filament progresses from inorganic oxide fibers such as zirconium oxide to stainless steel fibers, and then to catalysts sprayed onto the fiber surface or grown in situ.

4. The structured diaphragm according to claim 1, characterized in that, The surface of the structural reinforcing filament has a catalytic material, which can perform electrocatalysis when electricity is applied.

5. A method for preparing a structured diaphragm according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: Step A: Dissolve the polymer material in an organic solvent and mix thoroughly to obtain a mixed solution with a polymer mass fraction of less than 40 wt%. Step B: Arrange several structural reinforcing wires in an orderly manner on a flat plate, apply the mixed solution from Step A to the surface of the structural reinforcing wires, let it stand, and then attach the diaphragm body to the flat plate on which the structural reinforcing wires are laid. When attaching, adjust the angle between the structural reinforcing wires and the support line of the diaphragm body to be greater than 0 degrees and less than 90 degrees, or adjust the angle between the structural reinforcing wires and the vertical direction to be greater than or equal to 0 degrees and less than or equal to 45 degrees. Step C: The above-mentioned diaphragm body and the plate with several structural reinforcing wires laid on it are hot-pressed together, and the several structural reinforcing wires are bonded to the diaphragm body to obtain the structured composite membrane.

6. In the preparation method according to claim 5, the polymer material and organic solvent used in step A are the same as or similar to the casting agent components contained in the membrane body itself.

7. Use of the structured diaphragm of claim 1 for improving the tensile strength of the diaphragm along the direction of the structural reinforcing filaments.

8. The use of the structured membrane according to claim 1 for improving the hydrophilicity and conductivity of the membrane and increasing the catalytic activity per unit area of ​​the membrane, characterized in that, The structural reinforcing filament has catalytic function.

9. The use of the structured diaphragm according to claim 1 for regulating bubble behavior and reducing bubble accumulation, thereby increasing the current speed of alkaline water electrolysis.

10. An electrolytic cell, characterized in that, The electrolytic cell is equipped with a structured diaphragm. The diaphragm includes: a diaphragm body, and a structural reinforcement layer bonded to the diaphragm body; The membrane body is an alkaline water electrolysis composite membrane or an ion solvation membrane; Wherein, when the membrane body is an alkaline water electrolysis composite membrane: The alkaline water electrolysis composite diaphragm body has a support layer, the support layer has support lines, the structural reinforcement layer has structural reinforcement wires, the angle between the structural reinforcement wires and the support lines is greater than 0 degrees and less than 90 degrees, and when installed in the electrolytic cell, the angle between the structural reinforcement wires and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees. When the membrane body is an ion-solvated membrane: The angle between the structural reinforcing wire and the vertical direction is greater than or equal to 0 degrees and less than or equal to 45 degrees. The vertical direction refers to the direction parallel to gravity when the diaphragm is installed inside the electrolytic cell.

Images