Membrane for alkaline electrolyser and method of manufacturing thereof

Abstract

A separator for an alkaline electrolyzer that separates an alkaline electrolyzer containing an electrolyte into a cathode chamber and an anode chamber is proposed, the separator including: a base material layer having a plurality of micropores; two polymer layers formed with pores that are respectively attached to opposite two surfaces of the base material layer; and two inorganic material coating layers formed with pores that are respectively coated onto surfaces of the two polymer layers distal from the base material layer, wherein the plurality of micropores of the base material layer are formed not perpendicular to the two surfaces of the base material layer to allow the electrolyte to pass through the plurality of micropores and block hydrogen generated in the cathode chamber from being transferred to the anode chamber through the plurality of micropores during operation of the alkaline electrolyzer. A method of manufacturing a separator for an alkaline electrolyzer is also proposed. With the separator and the method, improved gas barrier performance, improved safety and reliability inside the alkaline electrolyzer, and reduced thickness of the separator are achieved.

Description

Technical Field

[0001] This invention relates to the field of renewable energy production. Specifically, it relates to a diaphragm for alkaline electrolyzers and a method for manufacturing the same. Background Technology

[0002] Alkaline electrolyzers are widely used for the production of renewable energy, specifically hydrogen and oxygen. An alkaline electrolyzer incorporates a diaphragm to divide its interior into a cathode chamber and an anode chamber. Essentially, the diaphragm must allow the electrolyte to pass through between the cathode and anode chambers while blocking hydrogen generated in the cathode chamber and oxygen generated in the anode chamber from passing through it; in other words, it must possess gas-barrier properties.

[0003] Figure 1 The diagram shows a cross-sectional view of a diaphragm for an alkaline electrolyzer according to the prior art. The diaphragm 1 generally comprises a polyphenylene sulfide (PPS) material layer 2 and two zirconium dioxide (ZrO2) coatings 3 and 4 coated on both sides of the PPS material layer 2. The PPS material layer 2 and the zirconium dioxide coatings 3 and 4 naturally possess multiple micropores due to their respective manufacturing processes, and the diaphragm 1 has a certain degree of hydrophilicity, allowing the electrolyte to pass through the diaphragm between the cathode and anode chambers when the diaphragm 1 is placed in the alkaline electrolyzer, while to some extent preventing hydrogen generated in the cathode chamber and oxygen generated in the anode chamber from passing through the diaphragm.

[0004] However, the aforementioned diaphragm 1 has insufficient gas barrier performance, allowing hydrogen gas to easily pass through the diaphragm 1 from the cathode chamber to the anode chamber. This is especially true when there are fluctuations in the hydrogen and oxygen generation process, such as a sudden increase in hydrogen yield. Due to the pressure difference between the electrolyte in the cathode and anode chambers, hydrogen gas can more easily pass through the diaphragm 1 to the anode chamber. To improve gas barrier performance, the aforementioned diaphragm 1 typically has a large thickness; however, this results in a large ohmic resistance in the diaphragm 1, leading to a higher voltage and greater energy consumption for the alkaline electrolyzer.

[0005] In view of the above problems, there is a need for an improved diaphragm for alkaline electrolyzers and a method for manufacturing the same. Summary of the Invention

[0006] This invention provides a diaphragm for an alkaline electrolyzer, which divides the alkaline electrolyzer containing electrolyte into a cathode chamber and an anode chamber, and the diaphragm comprises:

[0007] A substrate layer with multiple micropores;

[0008] Two porous polymer layers are formed on opposite surfaces of the substrate layer, respectively; and

[0009] Two porous inorganic material coatings are formed by coating two polymer layers onto the surfaces of the polymer layers that are away from the substrate layer.

[0010] The substrate layer has multiple micropores formed on two surfaces that are not perpendicular to the substrate layer, so that the electrolyte can pass through the multiple micropores during the operation of the alkaline electrolyzer and prevent the hydrogen generated in the cathode chamber from passing through the multiple micropores to the anode chamber.

[0011] The present invention also proposes a method for manufacturing a diaphragm for an alkaline electrolyzer, the diaphragm dividing the alkaline electrolyzer containing electrolyte into a cathode chamber and an anode chamber, and the method comprising:

[0012] A substrate layer with multiple micropores is provided, wherein the multiple micropores are formed on two opposite surfaces that are not perpendicular to the substrate layer, so as to allow the electrolyte to pass through the multiple micropores and block the hydrogen generated in the cathode chamber from passing through the multiple micropores to the anode chamber during the operation of the alkaline electrolyzer;

[0013] Two porous polymer layers are respectively attached to opposite surfaces of the substrate layer; and

[0014] Two porous inorganic material coatings are applied to the surfaces of two polymer layers away from the substrate layer to obtain a diaphragm. Attached Figure Description

[0015] Figure 1 A cross-sectional view of a diaphragm for an alkaline electrolyzer according to the prior art is shown;

[0016] Figure 2 A cross-sectional view of a diaphragm for an alkaline electrolyzer according to the present invention is shown;

[0017] Figures 3A to 3D The manufacturing process of the diaphragm for an alkaline electrolyzer according to the present invention is shown;

[0018] Figure 4 Show along Figure 3B A cross-sectional view of a portion of the diaphragm for an alkaline electrolyzer according to the invention, taken by line AA; and

[0019] Figure 5 This illustrates how the pressure difference between the electrolyte in the cathode chamber and the electrolyte in the anode chamber of an alkaline electrolyzer increases when... Figure 4 A cross-sectional view of a portion of the diaphragm. Detailed Implementation

[0020] The diaphragm for an alkaline electrolyzer and its manufacturing method according to the present invention will now be described in conjunction with the accompanying drawings.

[0021] Figure 2A cross-sectional view of the diaphragm for an alkaline electrolyzer according to the invention is shown. It should be noted that, apart from the diaphragm 10 according to the invention, the other components of the alkaline electrolyzer are known in the art and therefore are not shown in the figure. In simple terms, the alkaline electrolyzer includes a tank containing an electrolyte, the diaphragm dividing the tank into a cathode chamber and an anode chamber, with a cathode for generating hydrogen gas located adjacent to the diaphragm in the cathode chamber, and an anode for generating oxygen gas located adjacent to the diaphragm in the anode chamber.

[0022] like Figure 2 As shown, the diaphragm 10 according to the present invention divides an alkaline electrolytic cell containing electrolyte into a cathode chamber and an anode chamber, and the diaphragm 10 comprises:

[0023] A substrate layer 100 having multiple micropores;

[0024] Two porous polymer layers 200 are formed on opposite surfaces of the substrate layer 100, respectively; and

[0025] Two porous inorganic material coatings 300 are formed on the surfaces of the two polymer layers 200 that are away from the substrate layer 100.

[0026] The substrate layer 100 has multiple micropores formed on two surfaces that are not perpendicular to the substrate layer 100, so that during the operation of the alkaline electrolytic cell, the electrolyte can pass through the multiple micropores of the substrate layer 100 and prevent the hydrogen generated in the cathode chamber of the alkaline electrolytic cell from passing through the multiple micropores of the substrate layer 100 to the anode chamber of the alkaline electrolytic cell.

[0027] The following will combine Figures 3A to 3D The manufacturing process of the diaphragm 10 for an alkaline electrolyzer according to the present invention is described.

[0028] First, provide such Figure 3A The substrate membrane 110 shown is the precursor material for forming the substrate layer 100. It should be noted that since the diaphragm 10 will be placed in an alkaline electrolytic cell containing electrolyte, the diaphragm 10 needs to be resistant to strong alkalis and tear-resistant to prevent corrosion and tearing during operation in the alkaline electrolytic cell. Therefore, the substrate layer 100, as an important component of the diaphragm 10, should be resistant to strong alkalis and tear-resistant; that is, the substrate membrane 110, as the precursor material of the substrate layer 100, should be resistant to strong alkalis and tear-resistant.

[0029] Optionally, the substrate membrane 110 can be a polytetrafluoroethylene (PTFE) membrane, which not only has satisfactory resistance to strong alkalis and tear resistance, but is also easy to perforate and has a certain degree of flexibility. The advantages of the substrate membrane 110 used to form the substrate layer 100, i.e., the substrate layer 100 having flexibility, and consequently the entire diaphragm 10 having flexibility, will be described in detail later. It should be noted that although polytetrafluoroethylene is the preferred material for forming the substrate membrane 110, the invention is not limited thereto, and other suitable materials with strong alkali resistance and tear resistance can also be used to form the substrate membrane 110. Furthermore, the substrate membrane 110 is not limited to being formed from a single material, but can also be formed from a suitable mixture of two or more materials.

[0030] Then, as Figure 3B As shown, a plurality of micropores 120 are formed in the substrate film 110, wherein the plurality of micropores 120 are formed on two opposite surfaces that are not perpendicular to the substrate film 110 (e.g., from...). Figure 4 As can be seen, this allows the electrolyte to pass through these micropores during the operation of the alkaline electrolyzer and prevents the hydrogen generated in the cathode chamber of the alkaline electrolyzer from passing through these micropores and transferring to the anode chamber of the alkaline electrolyzer.

[0031] To allow electrolyte to pass through while blocking hydrogen gas, each of the plurality of micropores 120 can be fabricated with a pore size ranging from 0.1 μm to 1 μm. Multiple micropores with pore sizes within this range allow electrolyte to pass through while partially blocking hydrogen gas. It should be noted that... Figure 3B The number and distribution of the micropores 120 are merely illustrative and the invention is not limited thereto. The number and distribution of the micropores 120 can be determined accordingly based on the arrangement of the diaphragm 10 within the alkaline electrolyzer and the specific requirements for allowing electrolyte passage. For example, multiple micropores 120 may be uniformly distributed in the substrate membrane 110, but they may also be non-uniformly distributed; for example, the density of micropores may differ in different regions of the substrate membrane 110.

[0032] The applicant discovered that if the multiple micropores 120 are made perpendicular to the two surfaces of the substrate film 110, even if the multiple micropores 120 have a pore size within the aforementioned range, under certain operating conditions of the alkaline electrolyzer, hydrogen may still transfer from the cathode chamber of the alkaline electrolyzer through the multiple micropores 120 to the anode chamber. For example, when there are fluctuations in the hydrogen and oxygen generation process, such as a sudden increase in the hydrogen yield, the presence of a pressure difference between the electrolyte in the cathode chamber and the electrolyte in the anode chamber may cause hydrogen to transfer through the multiple micropores to the anode chamber under pressure.

[0033] Therefore, in this invention, the plurality of micropores 120 are formed on two surfaces that are not perpendicular to the substrate film 110. The cross-section of the plurality of micropores 120 is... Figure 4 As shown in the figure, Figure 4Show along Figure 3B The image shows a cross-sectional view of a portion of the diaphragm 10 for an alkaline electrolyzer according to the invention, taken by line AA. Figure 4 A portion of the substrate membrane 110 is shown in a vertical position. The membrane 10 has two opposite surfaces through which a plurality of micropores 120 pass: a cathode-side surface 111 adjacent to the cathode and an anode-side surface 112 adjacent to the anode, such that each of the plurality of micropores 120 has a cathode-side opening 121 adjacent to the cathode chamber on the cathode-side surface 111 and an anode-side opening 122 adjacent to the anode chamber on the anode-side surface 112. Figure 4 Arrow R is also shown, indicating the direction of movement of hydrogen gas in the form of bubbles generated in the cathode chamber during the operation of the alkaline electrolyzer. With the diaphragm 10 vertically positioned in the alkaline electrolyzer, the direction pointed to by arrow R is vertically upward, meaning that the bubbles generated in the cathode chamber will move vertically upward in the electrolyte within the alkaline electrolyzer along the direction pointed to by arrow R.

[0034] The multiple micropores 120 referred to in this article, formed on two surfaces not perpendicular to the substrate film 110, can be specifically understood as follows: during the operation of the alkaline electrolyzer, the hydrogen gas generated in the cathode chamber moves in the direction of movement (i.e., along) Figure 4 (In the direction of arrow R in the figure), the cathode-side opening 121 of each of the plurality of micropores 120 adjacent to the cathode chamber is higher than the anode-side opening 122 of the adjacent anode chamber. That is, the plurality of micropores 120 are inclined, such that when hydrogen gas moves in the vertically upward direction indicated by arrow R, the inclined plurality of micropores 120 shown in the figure can better prevent hydrogen gas from transferring from the cathode chamber through the plurality of micropores 120 to the anode chamber compared to a plurality of micropores formed perpendicular to the two surfaces of the substrate film 100.

[0035] like Figure 4 As shown, each of the plurality of micropores 120 is formed with an inclination angle θ relative to the normal directions perpendicular to the two surfaces of the substrate film 110, i.e., relative to the normal directions of the two surfaces of the substrate layer 100. Preferably, the inclination angle θ is in the range of 15° to 60°. The applicant has found that the plurality of micropores 120 having an inclination angle within this range both allows the electrolyte to pass through and effectively prevents hydrogen gas from the cathode chamber from transferring through the plurality of micropores 120 to the anode chamber.

[0036] The multiple micropores 120 of the substrate film 110 can be formed by conventional pore-forming methods, such as mechanical drilling or laser drilling. Multiple micropores 120 can be formed simultaneously in a single process, meaning each micropore can be formed with the same tilt angle θ, thus simplifying the formation process of the multiple micropores 120. However, the invention is not limited to this; different micropores among the multiple micropores 120 can be formed with different tilt angles. For example, at different locations on the membrane 10, such as different heights, the requirements for allowing electrolyte to pass through while simultaneously preventing hydrogen from transferring from the cathode chamber to the anode chamber through the multiple micropores 120 may differ, thus the tilt angles of the micropores at different locations, such as different heights, can also be different.

[0037] The applicant discovered that, depending on the different diffusion coefficients and molecular diameters of hydrogen and oxygen, given a fixed pore size (e.g., 0.1 μm to 1 μm) of the multiple micropores 120 in the substrate film 110, there is a risk of hydrogen transferring from the cathode chamber to the anode chamber through the multiple micropores 120, while there is almost no risk of oxygen transferring from the anode chamber to the cathode chamber through the multiple micropores 120. Therefore, as Figure 4 As shown, the multiple micropores 120 are designed to be inclined, so that even if the cathode-side opening 121 of each of the multiple micropores 120 adjacent to the cathode chamber is higher than the anode-side opening 122 of the adjacent anode chamber, it not only prevents hydrogen from transferring from the cathode chamber through the multiple micropores 120 to the anode chamber, but also does not increase the risk of oxygen transferring from the anode chamber through the multiple micropores 120 to the cathode chamber. In other words, the inclined design of the multiple micropores 120, combined with a specific range of pore sizes of the multiple micropores 120, achieves the optimal effect of allowing electrolyte to pass through the multiple micropores 120 while blocking hydrogen and oxygen from passing through the multiple micropores 120.

[0038] In obtaining Figure 3B After forming the substrate film 110 with a plurality of micropores 120 as shown, preferably the two opposite surfaces of the substrate film 110 are sulfonated to obtain the desired result. Figure 3C The substrate layer 100 shown has multiple micropores 120. That is, the substrate layer 100 can be obtained by sulfonating the two opposite surfaces of a substrate film 110 with multiple micropores, made of a material with strong alkali resistance and tear resistance. Sulfonation facilitates the adhesion of the two polymer layers 200, described later, to the two opposite surfaces of the substrate layer 100, and increases the hydrophilicity of the substrate layer 100, thereby promoting the passage of the electrolyte through the multiple micropores 120 of the substrate layer 100.

[0039] Next, as Figure 3DAs shown, two porous polymer layers 200 are respectively attached to two opposite surfaces of a substrate layer 100, and two porous inorganic material coatings 300 are coated on the surfaces of the two polymer layers 200 away from the substrate layer 100 to form the final diaphragm 10 according to the invention.

[0040] As the portion of the separator 10 intended to contact the electrolyte, the inorganic material coating 300 increases the hydrophilicity of the separator 10, thereby facilitating the passage of the electrolyte through the multiple micropores 120 of the separator 10. The inorganic material coating 300 can be, for example, a zirconium dioxide (ZrO2) or titanium dioxide (TiO2) coating, in which multiple pores naturally appear during formation; that is, the multiple pores in these coatings are formed naturally and randomly without the need for an additional drilling process. However, the invention is not limited thereto; the inorganic material coating 300 may additionally or alternatively be formed from other inorganic materials, and the inorganic material coating 300 may also be formed from a mixture of two or more inorganic materials.

[0041] If the two inorganic material coatings 300 are directly applied to opposite surfaces of the substrate layer 100, the multiple micropores 120 of the substrate layer 100 may be blocked by the inorganic material coatings 300, thereby preventing the electrolyte from passing through the multiple micropores 120 of the substrate layer 100 between the cathode and anode chambers of the alkaline electrolytic cell. To avoid this problem, two porous polymer layers 200 are also formed between the substrate layer 100 and the two inorganic material coatings 300. The two polymer layers 200 can be formed, for example, by one of the materials such as polyphenylene sulfide (PPS) and polypropylene (PP), or by a mixture of two or more polymers, and multiple pores will naturally appear during the formation of the two polymer layers 200. That is, the multiple pores in the two polymer layers 200 are formed naturally and randomly without the need for an additional drilling process. When two polymer layers 200 are attached to opposite surfaces of the substrate layer 100 and an inorganic material coating 300 is applied to the surfaces of the two polymer layers 200 away from the substrate layer 100, the multiple micropores 120 of the substrate layer 100 are not significantly blocked, so that the resulting diaphragm 10 allows the electrolyte to pass through the multiple micropores 120 while blocking hydrogen from transferring from the cathode chamber to the anode chamber through the multiple micropores.

[0042] Figure 1The diaphragm 1 of the prior art for alkaline electrolyzers, as shown, is typically thicker, for example, 500 μm or even greater, to improve gas barrier performance. Therefore, the diaphragm 1 has a high ohmic resistance, resulting in the alkaline electrolyzer requiring a higher voltage and consuming more energy. In contrast, due to the presence of the aforementioned plurality of micropores 120, the diaphragm 10 according to the invention can achieve better gas barrier performance than the prior art with a relatively smaller thickness. Specifically, in the diaphragm 10 according to the invention, the substrate layer 100 may have a thickness in the range of 50 μm to 100 μm, the two polymer layers 200 may each have a thickness of about 100 μm, the two inorganic material coatings 300 may each have a thickness in the range of 50 μm to 100 μm, and the entire diaphragm 10 may have a thickness in the range of 250 μm to 400 μm. Because the diaphragm 10 according to the invention has a relatively smaller thickness, it has a lower ohmic resistance, thereby requiring a lower voltage and consuming less energy to operate the alkaline electrolyzer.

[0043] It should be noted that Figure 4 The portion of the diaphragm 10 shown corresponds to the state when the diaphragm 10 does not undergo significant deformation. That is, it corresponds to the state where the diaphragm 10 is placed in an alkaline electrolytic cell, but there is no pressure difference or the pressure difference is small enough that the diaphragm 10 does not undergo significant deformation between the electrolyte in the cathode chamber and the electrolyte in the anode chamber. However, during the operation of the alkaline electrolytic cell, the generation rates of hydrogen in the cathode chamber and oxygen in the anode chamber are not always constant. Instead, there may be a sudden increase in the generation rate of hydrogen in the cathode chamber or a sudden increase in the generation rate of oxygen in the anode chamber. In this case, a pressure difference will occur between the electrolyte in the cathode chamber and the electrolyte in the anode chamber.

[0044] Figure 5 This illustrates how the pressure difference between the electrolyte in the cathode chamber and the electrolyte in the anode chamber of an alkaline electrolyzer increases when... Figure 4 A cross-sectional view of a portion of the diaphragm. (Compared to...) Figure 4 similar, Figure 5 Arrow R is also shown, indicating the direction of movement of hydrogen gas in the form of bubbles generated in the cathode chamber during the operation of the alkaline electrolyzer. The substrate membrane 110 of the diaphragm 10 according to the invention described above can be flexible, therefore, in... Figure 5 In this situation, the flexible diaphragm 10 deforms under the increased pressure difference, i.e., it is compressed, thereby compressing the multiple micropores 120, leading to... Figure 4Compared to reducing the pore size, this further prevents hydrogen gas from transferring from the cathode chamber to the anode chamber through multiple micropores 120 as it moves vertically upwards along the direction indicated by arrow R. It also prevents oxygen from transferring from the anode chamber to the cathode chamber through the micropores 120, but does not affect the passage of electrolyte through the micropores 120. In other words, with the diaphragm 10 being flexible, when the hydrogen generation rate in the cathode chamber or the oxygen generation rate in the anode chamber fluctuates, the diaphragm 10 can quickly and automatically respond, exhibiting a "self-sealing" characteristic. Therefore, under such fluctuating conditions, the gas barrier performance of the diaphragm 10 according to the present invention is improved, which further enhances the safety and reliability of the alkaline electrolyzer.

[0045] It should be noted that the term "increased pressure difference" as used in this article can refer to either an increase in the pressure difference caused by the electrolyte pressure in the cathode chamber being greater than that in the anode chamber, or an increase in the pressure difference caused by the electrolyte pressure in the anode chamber being greater than that in the cathode chamber. In both cases, the flexible diaphragm 10 will deform under the influence of the increased pressure difference, thereby reducing the pore size of the multiple micropores 120 and exhibiting a "self-sealing" characteristic. Furthermore, the term "increased pressure difference" as used in this article can refer to a situation where the pressure difference between the electrolyte in the cathode chamber and the electrolyte in the anode chamber changes from zero to non-zero, or it can refer to a situation where the difference increases to a certain threshold. This is because deformation may occur under different pressure differences depending on the material properties of the diaphragm 10, such as its flexibility and deformability.

[0046] The present invention also proposes a method for manufacturing a diaphragm for an alkaline electrolyzer, wherein the diaphragm divides the alkaline electrolyzer containing electrolyte into a cathode chamber and an anode chamber. The process of this method has been described above. Figures 3A to 3D The steps of this method are summarized below:

[0047] A substrate layer 100 is provided having a plurality of micropores 120, wherein the plurality of micropores 120 are formed on two opposite surfaces not perpendicular to the substrate layer 100, so as to allow the electrolyte to pass through the plurality of micropores 120 and block hydrogen generated in the cathode chamber from passing through the plurality of micropores 120 to the anode chamber during the operation of the alkaline electrolyzer.

[0048] Two porous polymer layers 200 are respectively attached to opposite surfaces of the substrate layer 100; and

[0049] Two porous inorganic material coatings 300 are respectively applied to the surfaces of two polymer layers 200 that are away from the substrate layer 100 to obtain a diaphragm 10.

[0050] The substrate layer 100 can be manufactured by providing a substrate film 110 with multiple micropores 120 made of a material that is resistant to strong alkalis and tear-resistant, and sulfonating the two opposite surfaces of the substrate film 110 to obtain the substrate layer 100.

[0051] The method may further include: forming each of the plurality of micropores 120 with a cathode-side opening 121 adjacent to the cathode chamber and an anode-side opening 122 adjacent to the anode chamber, wherein during the operation of the alkaline electrolyzer, in the direction of movement of hydrogen generated in the cathode chamber, the cathode-side opening 121 of each of the plurality of micropores 120 is higher than the anode-side opening 122. Each of the plurality of micropores 120 is formed with an inclination angle θ in the range of 15° to 60° relative to the normal directions of the two surfaces of the substrate layer 100.

[0052] The details of the above method have been described above in the section on the diaphragm for alkaline electrolyzers according to the present invention, and therefore will not be repeated here.

[0053] In summary, by utilizing the diaphragm for alkaline electrolyzers and its manufacturing method according to the present invention, improved gas barrier performance of the diaphragm is achieved. The diaphragm can rapidly and automatically respond to fluctuations in the hydrogen generation rate in the cathode chamber and the oxygen generation rate in the anode chamber during the operation of the alkaline electrolyzer, exhibiting a "self-sealing" characteristic, thereby improving the internal safety and reliability of the alkaline electrolyzer. Furthermore, the diaphragm can have a smaller thickness, resulting in a smaller ohmic resistance, which allows the alkaline electrolyzer to operate at a lower voltage and with lower energy consumption.

[0054] The foregoing, with reference to the accompanying drawings, describes in detail feasible but non-limiting embodiments of the diaphragm for an alkaline electrolyzer and its manufacturing method according to the present invention. Modifications and additions to the technology and structure, as well as recombinations of features in the various embodiments, should be considered within the scope of the invention by those skilled in the art, without departing from the scope and spirit of the invention as set forth in the following claims. Therefore, such modifications and additions conceivable under the teachings of this invention should be considered part of the invention. The scope of the invention is defined by the following appended claims and includes equivalent technologies known at the time of filing and those not yet foreseen.

Claims

1. A diaphragm (10) for an alkaline electrolytic cell, the diaphragm (10) dividing the alkaline electrolytic cell containing electrolyte into a cathode chamber and an anode chamber, and the diaphragm (10) comprising: A substrate layer (100) having multiple micropores (120); Two porous polymer layers (200) are formed on opposite surfaces of the substrate layer (100), respectively; and Two porous inorganic material coatings (300) are formed on the surfaces of the two polymer layers (200) that are away from the substrate layer (100). The plurality of micropores of the substrate layer (100) are formed not perpendicular to the two surfaces of the substrate layer (100) to allow the electrolyte to pass through the plurality of micropores (120) during operation of the alkaline electrolyzer and to prevent hydrogen generated in the cathode chamber from passing through the plurality of micropores and transferring to the anode chamber.

2. The diaphragm (10) according to claim 1, wherein each of the plurality of micropores (120) has a pore size in the range of 0.1 μm to 1 μm.

3. The diaphragm (10) according to claim 1, wherein the diaphragm (10) has a thickness in the range of 250 μm to 400 μm.

4. The diaphragm (10) according to claim 1, wherein the substrate layer (100) comprises a substrate membrane (110) formed with the plurality of micropores (120) made of a material having strong alkali resistance and tear resistance, and the two opposite surfaces of the substrate membrane (110) are sulfonated.

5. The diaphragm (10) according to any one of claims 1 to 4, wherein the substrate layer (100) is flexible.

6. The diaphragm (10) according to claim 5, wherein, When the pressure difference between the electrolyte in the cathode chamber and the electrolyte in the anode chamber increases, the diaphragm (10) deforms, causing the pore size of the plurality of micropores (120) to decrease.

7. The diaphragm (10) according to any one of claims 1 to 4, wherein each of the plurality of micropores (120) has a cathode-side opening (121) adjacent to the cathode chamber and an anode-side opening (122) adjacent to the anode chamber, and during operation of the alkaline electrolyzer, in the direction of movement of hydrogen generated in the cathode chamber, the cathode-side opening (121) of each of the plurality of micropores (120) is higher than the anode-side opening (122).

8. The diaphragm (10) according to claim 7, wherein, Each of the plurality of micropores (120) is formed with an inclination angle (θ) in the range of 15° to 60° relative to the normal direction of the two surfaces of the substrate layer (100).

9. A method of manufacturing a diaphragm (10) for an alkaline electrolytic cell, said diaphragm (10) dividing said alkaline electrolytic cell containing an electrolyte into a cathode chamber and an anode chamber, and said method comprising: A substrate layer (100) is provided having a plurality of micropores (120), wherein the plurality of micropores (120) are formed on two opposite surfaces not perpendicular to the substrate layer (100) to allow electrolyte to pass through the plurality of micropores (120) during operation of the alkaline electrolyzer and to prevent hydrogen generated in the cathode chamber from passing through the plurality of micropores (120) to the anode chamber; Two porous polymer layers (200) are respectively attached to opposite surfaces of the substrate layer (100); and Two porous inorganic material coatings (300) are respectively applied to the surfaces of the two polymer layers (200) away from the substrate layer (100) to obtain the diaphragm (10).

10. The method of claim 9, further comprising: Each of the plurality of micropores (120) is formed to have a cathode-side opening (121) adjacent to the cathode chamber and an anode-side opening (122) adjacent to the anode chamber, and during the operation of the alkaline electrolyzer, in the direction of movement of hydrogen generated in the cathode chamber, the cathode-side opening (121) of each of the plurality of micropores (120) is higher than the anode-side opening (122).

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