Functional diaphragm for high-pressure alkaline electrolyzer and preparation method thereof

Abstract

This invention discloses a functional diaphragm for high-pressure alkaline electrolyzers and its preparation method, belonging to the field of electrolytic hydrogen production technology. Starting from the core requirements of industrial alkaline electrolyzer diaphragms, this invention focuses on the key defects of existing diaphragms, such as poor gas barrier properties and low bubble point pressure, as well as the safety hazards caused by excessive hydrogen concentration in oxygen under high pressure and low load conditions. It provides a functional diaphragm for high-pressure alkaline electrolyzers, comprising sequentially connected anode isolation layers, multi-stage anode hydrogen elimination layers, a diaphragm substrate, and a cathode isolation layer. The multi-stage anode hydrogen elimination layers consist of at least two hydrogen elimination coating layers, and the content of hydrogen elimination catalyst in each layer decreases progressively from the diaphragm substrate towards the anode isolation layer. The preparation process of this functional diaphragm for high-pressure alkaline electrolyzers is simple, with excellent and stable hydrogen elimination performance, and it can ultimately achieve the goal of large-scale preparation of high-pressure electrolyzer diaphragms.

Description

Technical Field

[0001] This invention relates to the field of electrolytic hydrogen production technology, and in particular to a functional diaphragm for high-pressure alkaline electrolyzers and its preparation method. Background Technology

[0002] Hydrogen, with its high energy density, CO2-free combustion, and ease of storage and transportation, is increasingly valued by countries worldwide and is becoming an important supplement to future energy systems. Currently, mainstream hydrogen production methods both domestically and internationally include electrolysis, industrial by-product hydrogen production, and coal gasification. Among these, electrolysis has become the mainstream technology due to its advantages, such as using only water as raw material, effectively utilizing surplus wind and electricity, and requiring minimal equipment footprint. After years of development, electrolysis technology has evolved into various processes, with alkaline water electrolysis being particularly mature, cost-effective, and capable of large-scale production, gradually gaining industrial acceptance. Promoting the coupled development of green hydrogen and the coal chemical industry is a unique path for the efficient utilization of renewable energy, the green and low-carbon upgrading of traditional industries, and the achievement of high-level pollution and carbon reduction synergy. However, coal gasification plants are operating at increasingly higher pressures, while current green hydrogen (mainly from electrolysis) equipment typically operates at only 1.6 MPa, creating a significant pressure difference. Furthermore, the operating pressures of downstream purification and synthesis units are also much higher than the 1.6 MPa of electrolysis. This necessitates the addition of a compression stage when integrating green hydrogen and green oxygen into the grid, increasing not only equipment investment and energy consumption but also significantly raising project investment, operating costs, and safety risks due to the use of hydrogen / oxygen compressors. Therefore, increasing the pressure of electrolytic hydrogen production systems and developing high-pressure electrolytic hydrogen production equipment suitable for chemical hydrogen applications has become a key breakthrough direction for green and low-carbon technology innovation.

[0003] Compared to adding back-end pressurization equipment, improving electrolyzer performance by developing high-performance alkaline electrolyzer diaphragms is more feasible and economical. This improvement is particularly evident in reducing the hydrogen concentration in oxygen under high-pressure operating conditions and lowering overall operating costs. Currently, alkaline water electrolyzer diaphragms commonly use polyphenylene sulfide (PPS) fabric. The porous diaphragm separation structure in alkaline water electrolyzers leads to significant safety hazards due to the transmission of hydrogen and oxygen through the pores. Operation under high pressure and low load is particularly difficult. The core issue is that under high pressure, the hydrogen partial pressure increases, making it easier for hydrogen to permeate through the diaphragm to reach the oxygen side. Under low load, the oxygen production on the oxygen side decreases, ultimately leading to an increase in the hydrogen concentration in oxygen, posing a significant safety hazard to the electrolytic hydrogen production equipment and system. While composite diaphragms can reduce hydrogen in oxygen through higher bubble point pressure and lower pore size, the zirconium dioxide coating cannot eliminate hydrogen in oxygen; it can only suppress hydrogen in oxygen through physical barrier effects, limiting its application at higher pressures (≥3.2 MPa).

[0004] Therefore, there is an urgent need to develop a functional diaphragm for high-pressure alkaline electrolyzers that has the advantages of high oxygen-hydrogen suppression capability, low power consumption, good stability and easy industrial preparation, thereby further promoting the development of high-pressure hydrogen production technology. Summary of the Invention

[0005] The purpose of this invention is to provide a functional diaphragm for high-pressure alkaline electrolyzers and a method for preparing the same, so as to at least partially solve the above-mentioned problems of the prior art.

[0006] To achieve the above objectives, the present invention provides a functional diaphragm for a high-pressure alkaline electrolyzer, comprising an anode isolation layer, a multi-stage anode hydrogen elimination layer, a diaphragm substrate, and a cathode isolation layer that are sequentially connected. The multi-stage anode hydrogen removal layer consists of at least two hydrogen removal coating layers, and the content of hydrogen removal catalyst in each hydrogen removal coating layer decreases layer by layer along the direction from the membrane substrate to the anode isolation layer.

[0007] Optionally, the anode isolation layer and the cathode isolation layer independently include an oxide and an adhesive; The mass ratio of the oxide to the adhesive is 3~10:1; The oxide includes at least one of titanium oxide, cerium oxide, and zirconium oxide; The adhesive includes polysulfone adhesives; The thickness of the anode isolation layer is 50~150μm; The thickness of the cathode isolation layer is 50~150μm.

[0008] In this invention, by adding an oxide isolation layer, the hydrogen-eliminating coating can be prevented from being subjected to cavitation impact and electrochemical oxidation deactivation. The uniform gradient distribution of hydrogen-eliminating metal elements and coating materials can improve hydrogen elimination efficiency. The hydrogen-eliminating components located in the membrane channels and the hydrogen-eliminating coating on the membrane surface can play a synergistic role in hydrogen elimination, while also dispersing hot spots of the hydrogen elimination reaction, thereby improving coating stability and membrane durability.

[0009] Optionally, the multi-stage anode hydrogen removal layer is composed of 2 to 5 hydrogen removal coating layers; The hydrogen-removing coating includes a hydrogen-removing catalyst, an oxide, and a binder; The mass ratio of the hydrogen elimination catalyst to the oxide is 1:1~10; The mass ratio of the hydrogen-eliminating catalyst to the binder is 1~10:3; The hydrogen removal catalyst includes at least one of Pt, Pt / C, Pd, Pd / C, and Ag; The oxide includes at least one of titanium oxide, cerium oxide, and zirconium oxide; The adhesive includes polysulfone adhesives.

[0010] Optionally, the diaphragm substrate includes at least one of PPS cloth, PPS filament woven substrate, and PPS mesh film; The thickness of the diaphragm substrate is 150~850μm.

[0011] Optionally, the overall thickness of the functional diaphragm used in the high-pressure alkaline electrolytic cell is 550~980μm, and the sheet resistivity is 0.2~0.35Ω / cm. 2 The bubble point pressure is 0.2~3 Bar, and the average pore diameter is 0.03~0.3 μm.

[0012] In this invention, an anode isolation layer, a multi-stage anode hydrogen elimination layer, and a cathode isolation layer are added to a traditional PPS cloth. The anode isolation layer efficiently transfers hydroxide ions without affecting electrolysis performance; furthermore, it prevents electron conduction, isolating the hydrogen elimination layer from the high-potential working environment and preventing the hydrogen elimination catalyst from electrochemical oxidation and deactivation, thus ensuring the membrane's hydrogen elimination stability. The multi-stage anode hydrogen elimination layer is uniform and dense, effectively catalyzing the decomposition of hydrogen permeating from the membrane, and its gradient distribution of catalytic active sites effectively reduces the hot spot effect of hydroxide oxidation. Compared to a direct connection between the hydrogen elimination layer and the anode electrode, the anode isolation layer, located in the middle, ensures a tighter connection between the two, making the catalytic layer less susceptible to detachment due to bubble impact, thus improving the membrane's structural stability and durability.

[0013] Secondly, the present invention provides a method for preparing a functional diaphragm for a high-voltage alkaline electrolyzer, wherein the functional diaphragm for the high-voltage alkaline electrolyzer is as described above, and the preparation method includes the following steps: Pretreatment of the diaphragm substrate: Immerse the diaphragm substrate in an alcohol-water solution, wash with pure water and dry before use; Preparation of multi-stage anode hydrogen removal layer: Hydrogen removal catalyst, binder and organic solvent are mixed and stirred for the first time. Oxide is added and prepared in batches according to the mass ratio of hydrogen removal catalyst and oxide. The second stirring and degassing treatment are carried out in sequence to obtain the multi-stage anode hydrogen removal layer. Preparation of the anode isolation layer: The adhesive and organic solvent are mixed, stirred for the first time, and then the oxide is added. The mixture is then stirred for the second time and degassing is performed to obtain the anode isolation layer. The preparation of the cathode isolation layer is the same as that of the anode isolation layer. Preparation of a functional diaphragm for a high-pressure alkaline electrolyzer: Coating is performed in the following order: anode isolation layer, multi-stage anode hydrogen elimination layer, diaphragm substrate, and cathode isolation layer. The multi-stage anode hydrogen elimination layer consists of at least two hydrogen elimination coating layers, and the content of hydrogen elimination catalyst in each hydrogen elimination coating layer decreases progressively from the diaphragm substrate towards the anode isolation layer. After scraping, drying, and water bath phase conversion, the functional diaphragm for the high-pressure alkaline electrolyzer is obtained.

[0014] Optionally, in the pretreatment step of the membrane substrate, the alcohol in the alcohol-water solution includes ethanol or isopropanol; The temperature of the alcohol-water solution is 35~45℃; The mass ratio of alcohol to water in the alcohol-water solution is 1:3~5; The immersion time is 1.5 to 2.5 hours; The drying temperature is 80~110℃.

[0015] In this application, the membrane substrate is immersed in an ethanol-water solution to remove surface-adsorbed impurities.

[0016] Optionally, in the preparation step of the multi-stage anode hydrogen removal layer, the organic solvent is an N,N-dimethylformamide solution; the first stirring speed is 250-350 r / min; the first stirring time is 2.5-3.5 h; the mass ratio of the hydrogen removal catalyst to the oxide is 1:1-10; the second stirring speed is 800-1200 r / min; the second stirring time is 20-25 h; and the degassing treatment is carried out using a vacuum stirring degassing machine, with the parameters set as follows: vacuum degree 0.1 mbar, air pump flow rate 5 m³ / s. 3 / h, the degassing treatment time is 0.8~1.2h.

[0017] Optionally, in the preparation step of the anode isolation layer, the organic solvent is an N,N-dimethylformamide solution; the first stirring speed is 250-350 r / min, and the first stirring time is 2.5-3.5 h; the second stirring speed is 800-1200 r / min, and the second stirring time is 20-25 h; the degassing treatment is carried out using a vacuum stirring degassing machine, and the parameters of the vacuum stirring degassing machine are set as follows: vacuum degree of 0.1 mbar, air pump flow rate of 5 m³ / s. 3 / h, the degassing treatment time is 0.8~1.2h.

[0018] Optionally, in the preparation step of the functional diaphragm for the high-pressure alkaline electrolytic cell, the drying temperature is 80~90℃, the drying time is 25~35min, the water bath phase transition temperature is 10~20℃, and the water bath phase transition time is 25~35min.

[0019] The membrane preparation method used in this invention has advantages such as simple preparation process, good batch consistency of membrane preparation, and ability to meet the needs of large-scale preparation of large-size membranes.

[0020] Compared with the prior art, the present invention has at least the following advantages: The functional diaphragm for high-pressure alkaline electrolyzers provided by this invention comprises, in sequence, an anode isolation layer, a multi-stage anode hydrogen removal layer, a diaphragm substrate, and a cathode isolation layer, forming a gradient-distributed integrated hydrogen removal diaphragm (the gradient is reflected in the different amounts of catalyst added in different anode hydrogen removal layers). This functional diaphragm, through its unique composite functional coating design, enables the efficient catalytic oxidation of trace amounts of hydrogen permeating the diaphragm within the membrane layer, thereby effectively blocking hydrogen-oxygen cross-membrane migration. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the functional diaphragm for a high-pressure alkaline electrolytic cell provided by the present invention.

[0022] Figure label: 1. Anode isolation layer; 2. Multi-stage anode hydrogen removal layer; 3. Diaphragm substrate; 4. Cathode isolation layer.

[0023] Figure 2 A physical image of the functional diaphragm for high-pressure alkaline electrolytic cells provided by the present invention.

[0024] Figure 3 The graph shows the hydrogen data in oxygen measured by the diaphragm in the embodiments and comparative examples of the present invention.

[0025] Figure 4 The following are polarization curves of the diaphragm test in the embodiments and comparative examples of the present invention (Note: the test conditions were a hydrogen production rate of 1 Nm³ in the electrolyzer). 3 / h, diaphragm diameter 260mm, number of chambers 8, current density 6000A / m 2 The reaction temperature is 80℃, the alkali solution circulation flow rate is 80L / h, and the anode and cathode are commercial Raney nickel electrodes; the support mesh is a plate mesh structure. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate to understand the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0028] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0029] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0030] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] The schematic diagrams and physical images of the functional diaphragms for high-voltage alkaline electrolyzers prepared in the following examples are shown below. Figure 1 and Figure 2 As shown. Example 1

[0033] A method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell, comprising the following steps: (1) Substrate pretreatment: Immerse 850mm thick PPS filament braided substrate (30×30cm) in 1L of 40℃ water and ethanol (4:1) solution for 2h, wash and dry for later use.

[0034] (2) Preparation of multi-stage anode hydrogen removal layer slurry: 1g of Pt black with a diameter of 25nm was added to 200ml of N,N-dimethylformamide (DMF) solution containing polysulfone binder (polysulfone to Pt black ratio = 1:3). The mixture was stirred at 300r / min for 3h. Then, zirconium oxide with a particle size of 50nm was added. The ratio of oxide to hydrogen removal catalyst was (4:1, 3:1, 1:1). The mixture was prepared in three batches according to the different proportions of hydrogen removal catalyst. The mixture was stirred at 1000r / min for 24h. Then, the mixed solution was transferred to a vacuum stirrer for degassing treatment for 1h to obtain the multi-stage anode hydrogen removal layer slurry. (3) Preparation of anode isolation layer slurry: Similar to the multi-stage anode hydrogen removal isolation layer, but without adding catalyst; 200 ml of DMF solution containing polysulfone binder is stirred at 300 r / min for 1 h, and then zirconia with a particle size of 50 nm is added and stirred at 1000 r / min for 24 h. Then the mixed solution is transferred to a vacuum stirrer for degassing treatment for 1 h to obtain anode isolation layer slurry; (4) Preparation of cathode isolation layer slurry: The preparation steps are the same as those of anode isolation layer slurry, and the thickness of the isolation layer for both cathode and anode is 100 μm; (5) Preparation of gradient distribution integrated hydrogen removal membrane: The membrane was coated sequentially as follows: anode isolation layer, multi-stage anode hydrogen removal layer, membrane and cathode isolation layer. The multi-stage anode hydrogen removal layer was prepared by coating slurry with different catalyst proportions, and divided into 3 layers with the proportion at the membrane contact point from high to low. The slurry film was prepared by a scraping process. The height of the scraper was adjusted, the scraper was slid at a uniform speed, and then the slurry was poured and scraped at a uniform speed. The thickness of the slurry film was adjusted by the height of the scraper. The scraped slurry film was placed in an oven for drying. The temperature of the oven was 85℃ and the drying time was 30min. Phase transformation: The pretreated slurry membrane was placed in a water bath at 15°C for phase transformation. After 30 minutes of phase transformation, a gradient-distributed integrated hydrogen removal membrane was obtained. Example 2

[0035] A method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell, comprising the following steps: (1) Substrate pretreatment: Immerse a 350 mm thick PPS mesh film (30×30 cm) in 1 L of 40 °C water and ethanol (4:1) solution for 2 h, wash and dry for later use.

[0036] (2) Preparation of multi-stage anode hydrogen removal layer slurry: 1g of Pt / C (Pt percentage content is 40wt%) is added to 200ml of N,N-dimethylformamide (DMF) solution containing polysulfone binder (polysulfone to Pt / C ratio = 1:3), and stirred at 300r / min for 3h. Then, zirconium oxide with a particle size of 100nm is added. The ratio of oxide to hydrogen removal catalyst is (2:1, 1:1). The preparation is carried out in two batches according to the different proportions of hydrogen removal catalyst. The mixture is stirred at 1000r / min for 24h. Then, the mixed solution is transferred to a vacuum stirrer for degassing treatment for 1h to obtain the multi-stage anode hydrogen removal layer slurry. (3) Preparation of anode isolation layer slurry: Similar to the multi-stage anode hydrogen removal isolation layer, but without adding catalyst; 200 ml of DMF solution containing polysulfone binder is stirred at 300 r / min for 1 h, and then zirconium oxide with a particle size of 100 nm is added and stirred at 1000 r / min for 24 h. Then the mixed solution is transferred to a vacuum stirrer for degassing treatment for 1 h to obtain anode isolation layer slurry; (4) Preparation of cathode isolation layer slurry: The preparation steps are the same as those of anode isolation layer slurry, and the thickness of the isolation layer for both cathode and anode is 100 μm; (5) Preparation of gradient distribution integrated hydrogen removal membrane: The membrane was coated sequentially as follows: anode isolation layer, multi-stage anode hydrogen removal layer, membrane and cathode isolation layer. The multi-stage anode hydrogen removal layer was prepared by coating slurry with different catalyst proportions, and divided into two layers with the proportion at the membrane contact point decreasing from high to low. The slurry film was prepared by a scraping process. The height of the scraper was adjusted, the scraper was slid at a uniform speed, and then the slurry was poured and scraped at a uniform speed. The thickness of the slurry film was adjusted by the height of the scraper. The scraped slurry film was placed in an oven for drying. The temperature of the oven was 85℃ and the drying time was 30min. Phase transformation: The pretreated slurry membrane was placed in a water bath at 15°C for phase transformation. After 30 minutes of phase transformation, a gradient-distributed integrated hydrogen removal membrane was obtained. Example 3

[0037] A method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell, comprising the following steps: (1) Substrate pretreatment: Immerse a 650mm thick PPS cloth (30×30cm) in a 1L solution of water and ethanol (4:1) at 40℃ for 2h, wash and dry for later use.

[0038] (2) Preparation of multi-stage anode hydrogen removal layer slurry: 1g of Pd black with a diameter of 50nm was added to 200ml of N,N-dimethylformamide (DMF) solution containing polysulfone binder (polysulfone to Pd black ratio = 1:3). The mixture was stirred at 300r / min for 3h. Then, titanium oxide with a particle size of 100nm was added. The ratio of oxide to hydrogen removal catalyst was (5:1, 4:1, 3:1, 1:1). The mixture was prepared in four batches according to the different proportions of hydrogen removal catalyst. The mixture was stirred at 1000r / min for 24h. Then, the mixed solution was transferred to a vacuum stirrer for degassing treatment for 1h to obtain the multi-stage anode hydrogen removal layer slurry. (3) Preparation of anode isolation layer slurry: Similar to the multi-stage anode hydrogen removal isolation layer, but without adding catalyst; 200 ml of DMF solution containing polysulfone binder is stirred at 300 r / min for 1 h, and then titanium oxide with a particle size of 100 nm is added and stirred at 1000 r / min for 24 h. Then the mixed solution is transferred to a vacuum stirrer for degassing treatment for 1 h to obtain anode isolation layer slurry; (4) Preparation of cathode isolation layer slurry: The preparation steps are the same as those of anode isolation layer slurry, and the thickness of the isolation layer for both cathode and anode is 50 μm; (5) Preparation of gradient distribution integrated hydrogen removal membrane: The membrane was coated sequentially as follows: anode isolation layer, multi-stage anode hydrogen removal layer, membrane and cathode isolation layer. The multi-stage anode hydrogen removal layer was prepared by coating slurry with different catalyst proportions, and divided into 4 layers with the proportion at the membrane contact point from high to low. The slurry film was prepared by a scraping process. The height of the scraper was adjusted, the scraper was slid at a uniform speed, and then the slurry was poured and scraped at a uniform speed. The thickness of the slurry film was adjusted by the height of the scraper. The scraped slurry film was placed in an oven for drying. The temperature of the oven was 85℃ and the drying time was 30min. Phase transformation: The pretreated slurry membrane was placed in a water bath at 15°C for phase transformation. After 30 minutes of phase transformation, a gradient-distributed integrated hydrogen removal membrane was obtained. Comparative Example 1

[0039] Compared to Example 1, the only difference is the omission of the multi-stage anode hydrogen removal layer: (1) Matrix pretreatment: Immerse a PPS membrane (30×30cm) with a thickness of 850mm in 1L of water and ethanol (4:1) solution at 40℃ for 2h, wash and dry for later use.

[0040] (2) Preparation of anodic isolation layer slurry: 200 ml of DMF solution containing polysulfone binder was stirred at 300 r / min for 1 h, and then zirconia with a particle size of 50 nm was added and stirred at 1000 r / min for 24 h. The mixed solution was then transferred to a vacuum stirrer for degassing treatment for 1 h to obtain the anodic isolation layer slurry. (3) Preparation of cathode isolation layer slurry: The preparation steps are the same as those of anode isolation layer slurry, and the thickness of the isolation layer for both cathode and anode is 100 μm; (4) Preparation of composite membrane: The anodic isolation layer, the membrane and the cathode isolation layer are coated in sequence. The slurry film is prepared by scraping. The height of the scraper is adjusted and the scraper is slid at a uniform speed. The slurry is then poured and scraped at a uniform speed. The thickness of the slurry film is adjusted by the height of the scraper. The slurry film after scraping is placed in an oven for drying. The temperature of the oven is 85℃ and the drying time is 30min. Phase transformation: The pretreated slurry membrane was placed in a water bath at 15°C for phase transformation. After 30 minutes of phase transformation, a composite membrane was obtained. Comparative Example 2

[0041] Compared to Example 1, the only difference is the omission of the anode and cathode isolation layers: A method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell, comprising the following steps: (1) Matrix pretreatment: Immerse a PPS membrane (30×30cm) with a thickness of 850mm in 1L of water and ethanol (4:1) solution at 40℃ for 2h, wash and dry for later use.

[0042] (2) Preparation of multi-stage anode hydrogen removal layer slurry: 1g of Pt black with a diameter of 25nm was added to 200ml of N,N-dimethylformamide (DMF) solution containing polysulfone binder (polysulfone to Pt black ratio = 1:3). The mixture was stirred at 300r / min for 3h. Then, zirconium oxide with a particle size of 50nm was added. The ratio of oxide to hydrogen removal catalyst was (4:1, 3:1, 1:1). The mixture was prepared in three batches according to the different proportions of hydrogen removal catalyst. The mixture was stirred at 1000r / min for 24h. Then, the mixed solution was transferred to a vacuum stirrer for degassing treatment for 1h to obtain the multi-stage anode hydrogen removal layer slurry. (3) Preparation of composite membrane: The multi-stage anode hydrogen elimination layer and the membrane were coated sequentially. The multi-stage anode hydrogen elimination layer was prepared by coating slurry with different catalyst ratios, and the membrane was divided into 3 layers with the ratio at the membrane contact point from high to low. The slurry film was prepared by a scraping process. The height of the scraper was adjusted, the scraper was slid at a uniform speed, and then the slurry was poured and scraped at a uniform speed. The thickness of the slurry film was adjusted by the height of the scraper. The scraped slurry film was placed in an oven for drying. The temperature of the oven was 85℃ and the drying time was 30min. Phase transformation: The pretreated slurry membrane was placed in a water bath at 15°C for phase transformation. After 30 minutes of phase transformation, a composite membrane was obtained. Comparative Example 3

[0043] Compared with Example 1, the only difference is that the Pt black in the multi-stage anodic hydrogen removal layer is replaced with Ni black. Comparative Example 4

[0044] Compared to Example 1, the only difference is that the zirconium oxide in the isolation layer is replaced with nickel oxide of the same size. Experimental Example

[0045] The composite membranes prepared in Examples 1-3 and Comparative Examples 1-4 were tested.

[0046] The test conditions were as follows: the cathode was a Raney nickel cathode electrode, the anode was a Raney nickel anode electrode, the electrode diameter was 140 mm, the hydrogen tank outlet temperature was 80℃, there were 8 small chambers, the alkali solution was 30 wt / % KOH, the structure was a flat plate support using a diamond-shaped support mesh, and the alkali solution flow rate was 0.08 m³ / min. 3 / h, mixed circulation, test pressure 0~3.2mPa. The diaphragm used was a conventional commercial PPS diaphragm (850μm) and composite diaphragms prepared in Examples 1-3 and Comparative Examples 1-4. Tested at 6000A / m. 2 Average cell voltage and hydrogen concentration in oxygen at current density. Results are shown in Table 1. Figure 3 and Figure 4 As shown.

[0047] Table 1 Test Results Grouping Thickness (μm) <![CDATA[Grammage (g / m 2 )]]> <![CDATA[Sheet Resistance (Ω / cm 2 )]]> Bubble pressure (Bar) Average pore diameter (μm) <![CDATA[Average cell voltage / V @ 6000 A / m 2 > <![CDATA[Hydrogen concentration in oxygen on the anode side (%) @ 6000 A / m 2 @ 3.2 MPa]]> Commercial PPS separator 850 430 0.25 0.2 5 1.88 1.68 Example 1 979 472 0.21 2.2 0.1 1.78 1.24 Example 2 580 365 0.13 2.1 0.12 1.72 1.36 Example 3 753 385 0.18 2.5 0.11 1.75 1.29 Comparative Example 1 960 453 0.21 2.2 0.1 1.78 1.53 Comparative Example 2 850 440 0.24 0.2 5 1.86 1.38 Comparative Example 3 972 475 0.22 2.2 0.1 1.79 1.54 Comparative Example 4 981 473 0.28 2.2 0.1 1.95 1.29 As shown in Table 1, in this invention, an anode isolation layer, a multi-stage anode hydrogen elimination layer, and a cathode isolation layer are added to the PPS cloth, PPS filament woven substrate, or PPS mesh membrane. The anode / cathode isolation layer, on the one hand, improves the hydrophilicity of the membrane, efficiently transfers hydroxide ions, enhances electrolysis performance, reduces the chamber voltage (reducing energy consumption), and significantly reduces the membrane pore size, improving the membrane's physical barrier against gas transport. On the other hand, the anode isolation layer cannot conduct electrons, isolating the hydrogen elimination layer from the high-potential working environment and ensuring the stability of the membrane's hydrogen elimination performance. The multi-stage anode hydrogen elimination layer is uniform and dense, effectively catalyzing the decomposition of hydrogen permeating from the membrane. Furthermore, the gradient distribution of catalytic active sites effectively reduces the hotspot effect of hydrogen catalytic oxidation, preventing localized overheating damage to the membrane. Compared to a direct connection between the hydrogen elimination layer and the anode electrode, the anode isolation layer, located in the middle, ensures a tighter connection between the two, making the catalytic layer less susceptible to bubble impact and detachment, thus improving the structural stability and durability of the membrane. Therefore, compared to the traditional PPS cloth diaphragm, Example 1 showed a significantly increased bubble point pressure, and significantly reduced diaphragm pore size, chamber voltage, and hydrogen concentration in oxygen at the same current density. In Comparative Example 1, without the addition of a multi-stage anode hydrogen removal layer, the hydrogen concentration in oxygen was higher than in Example 1 due to the physical barrier effect of the isolation coating alone. In Comparative Example 2, without the addition of an isolation coating, the hydrogen removal coating alone eliminated hydrogen in oxygen through catalytic oxidation, resulting in a higher hydrogen concentration in oxygen than in Example 1. In Comparative Example 3, replacing the platinum-based catalyst with a nickel-based material, the prepared hydrogen removal coating showed no significant catalytic oxidation ability to eliminate hydrogen in oxygen, resulting in a higher hydrogen concentration in oxygen than in Example 1. In Comparative Example 4, replacing the zirconium oxide coating with a nickel-based material, the prepared isolation coating exhibited higher sheet resistance and an increased electrolysis chamber voltage, exceeding that of Example 1.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A functional diaphragm for a high-voltage alkaline electrolytic cell, characterized in that, It includes an anode isolation layer, a multi-stage anode hydrogen elimination layer, a membrane substrate, and a cathode isolation layer that are connected in sequence. The multi-stage anode hydrogen removal layer consists of at least two hydrogen removal coating layers, and the content of hydrogen removal catalyst in each hydrogen removal coating layer decreases layer by layer along the direction from the membrane substrate to the anode isolation layer.

2. The functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 1, characterized in that, The anode isolation layer and the cathode isolation layer each independently comprise an oxide and an adhesive; The mass ratio of the oxide to the adhesive is 3~10:1; The oxide includes at least one of titanium oxide, cerium oxide, and zirconium oxide; The adhesive includes polysulfone adhesives; The thickness of the anode isolation layer is 50~150μm; The thickness of the cathode isolation layer is 50~150μm.

3. The functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 1, characterized in that, The multi-stage anode hydrogen removal layer consists of 2 to 5 hydrogen removal coating layers; The hydrogen-removing coating includes a hydrogen-removing catalyst, an oxide, and a binder; The mass ratio of the hydrogen elimination catalyst to the oxide is 1:1~10; The mass ratio of the hydrogen-eliminating catalyst to the binder is 1~10:3; The hydrogen removal catalyst includes at least one of Pt, Pt / C, Pd, Pd / C, and Ag; The oxide includes at least one of titanium oxide, cerium oxide, and zirconium oxide; The adhesive includes polysulfone adhesives.

4. The functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 1, characterized in that, The diaphragm substrate includes at least one of PPS cloth, PPS filament woven substrate, and PPS mesh film. The thickness of the diaphragm substrate is 150~850μm.

5. The functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 1, characterized in that, The functional diaphragm used in the high-pressure alkaline electrolytic cell has an overall thickness of 550~980μm and a sheet resistivity of 0.2~0.35Ω / cm. 2 The bubble point pressure is 0.2~3 Bar, and the average pore diameter is 0.03~0.3 μm.

6. A method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell, characterized in that, The functional diaphragm for the high-voltage alkaline electrolytic cell is as described in any one of claims 1 to 5, and its preparation method includes the following steps: Pretreatment of the diaphragm substrate: Immerse the diaphragm substrate in an alcohol-water solution, wash with pure water and dry before use; Preparation of multi-stage anode hydrogen removal layer: Hydrogen removal catalyst, binder and organic solvent are mixed and stirred for the first time. Oxide is added and prepared in batches according to the mass ratio of hydrogen removal catalyst and oxide. The second stirring and degassing treatment are carried out in sequence to obtain the multi-stage anode hydrogen removal layer. Preparation of the anode isolation layer: The adhesive and organic solvent are mixed, stirred for the first time, and then the oxide is added. The mixture is then stirred for the second time and degassing is performed to obtain the anode isolation layer. The preparation of the cathode isolation layer is the same as that of the anode isolation layer. Preparation of a functional diaphragm for a high-pressure alkaline electrolyzer: Coating is performed in the following order: anode isolation layer, multi-stage anode hydrogen elimination layer, diaphragm substrate, and cathode isolation layer. The multi-stage anode hydrogen elimination layer consists of at least two hydrogen elimination coating layers, and the content of hydrogen elimination catalyst in each hydrogen elimination coating layer decreases progressively from the diaphragm substrate towards the anode isolation layer. After scraping, drying, and water bath phase conversion, the functional diaphragm for the high-pressure alkaline electrolyzer is obtained.

7. The method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 6, characterized in that, In the pretreatment step of the membrane substrate, the alcohol in the alcohol-water solution includes ethanol or isopropanol; The temperature of the alcohol-water solution is 35~45℃; The mass ratio of alcohol to water in the alcohol-water solution is 1:3~5; The immersion time is 1.5 to 2.5 hours; The drying temperature is 80~110℃.

8. The method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 6, characterized in that, In the preparation step of the multi-stage anode hydrogen removal layer, the organic solvent is N,N-dimethylformamide solution; the first stirring speed is 250~350 r / min, the first stirring time is 2.5~3.5 h, the mass ratio of the hydrogen removal catalyst to the oxide is 1:1~10; the second stirring speed is 800~1200 r / min, the second stirring time is 20~25 h; the degassing treatment is carried out using a vacuum stirring degassing machine, the parameters of which are set as follows: vacuum degree 0.1 mbar, air pump flow rate 5 m³ / s. 3 / h, the degassing treatment time is 0.8~1.2h.

9. The method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 6, characterized in that, In the preparation step of the anode isolation layer, the organic solvent is N,N-dimethylformamide solution. The first stirring speed is 250~350 r / min, and the first stirring time is 2.5~3.5 h. The second stirring speed is 800~1200 r / min, and the second stirring time is 20~25 h. The degassing treatment is carried out using a vacuum stirring degassing machine, and the parameters of the vacuum stirring degassing machine are set as follows: vacuum degree of 0.1 mbar and air pump flow rate of 5 m³ / h. 3 / h, the degassing treatment time is 0.8~1.2h.

10. The method for preparing a functional diaphragm for a high-voltage alkaline electrolytic cell according to claim 6, characterized in that, In the preparation step of the functional diaphragm for high-pressure alkaline electrolytic cells, the drying temperature is 80~90℃, the drying time is 25~35min, the water bath phase transformation temperature is 10~20℃, and the water bath phase transformation time is 25~35min.

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