Diaphragm for alkaline water electrolysis, method for producing same, and alkaline water electrolysis cell

Abstract

Disclosed is a diaphragm for alkaline water electrolysis, which separates an anode chamber and a cathode chamber of an alkaline water electrolysis cell. This diaphragm for alkaline water electrolysis is provided with a polymer porous film which integrally has a sealing region that is sandwiched by cell constituent members in the alkaline water electrolysis cell, an edge region that is disposed on the outer peripheral side of the sealing region, and a separator region that is disposed on the inner peripheral side of the sealing region. The sealing region has a shape surrounding the separator region, and has a bulk part for preventing permeation of an electrolyte solution through the pores of the polymer porous film.

Description

Diaphragm for alkaline water electrolysis, method for manufacturing the same, and alkaline water electrolytic cell

[0001] The present disclosure relates to a diaphragm for alkaline water electrolysis and an alkaline water electrolytic cell including the same.

[0002] In recent years, hydrogen has been used in combustion and reactions to ２ Because it does not produce hydrogen, it has attracted attention as an environmentally friendly, clean energy source. Alkaline water electrolysis is a well-known method for producing hydrogen. Alkaline water electrolysis generates hydrogen and oxygen by electrolyzing water using an alkaline aqueous solution as the electrolyte.

[0003] A known electrolytic cell used in alkaline water electrolysis has a structure in which a porous diaphragm is placed between an anode chamber and a cathode chamber. The diaphragm is sandwiched between a frame that forms the anode chamber and a frame that forms the cathode chamber, and is sandwiched on both sides by these frames, with a gasket sealing the gap between the diaphragm and the frame. The diaphragm is larger than the gasket and protrudes beyond the gasket to the outside of the cell. As a result, the gasket alone is not sufficient to prevent leakage of the electrolyte, and there has been an issue of electrolyte leaking out of the cell through the pores in the diaphragm.

[0004] In view of this, in the alkaline water electrolytic cell of Patent Document 1, the frame-shaped gasket has a slit that accommodates the peripheral edge of the porous diaphragm, and the gasket covers the entire peripheral edge of the diaphragm so that the porous diaphragm is not exposed to the outside of the cell, thereby preventing leakage of the electrolytic solution to the outside of the cell.

[0005] Patent No. 6559383

[0006] In an electrolytic cell, it is desirable that the diaphragm be tensioned without any slack, because looseness in the diaphragm reduces the efficiency of contact with the electrodes and the like, thereby reducing the efficiency of the electric field. In the process of assembling an electrolytic cell, in order to sandwich the diaphragm between gaskets while reliably applying tension to the diaphragm, it is convenient to have a structure in which the diaphragm protrudes outside the cell, as in the past. With such a structure, the tension of the diaphragm can be easily adjusted, for example, by pulling the diaphragm from outside the gasket at an appropriate time during the process of assembling the electrolytic cell.

[0007] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a technology for suppressing leakage of an electrolytic solution to the outside of an alkaline water electrolysis cell through a diaphragm in an alkaline water electrolysis cell having a structure in which a porous diaphragm for alkaline water electrolysis protrudes to the outside of the cell.

[0008] In order to solve the above problems, a diaphragm for alkaline water electrolysis according to one aspect of the present disclosure is a diaphragm for alkaline water electrolysis separating an anode chamber and a cathode chamber of an alkaline water electrolytic cell, comprising a porous polymer membrane integrally having: a seal region to be sandwiched between cell-constituting members of the alkaline water electrolytic cell, an edge region arranged on the outer periphery of the seal region, and a separator region arranged on the inner periphery of the seal region, wherein the seal region has a shape surrounding the separator region and has a bulk portion that prevents permeation of an electrolyte through pores in the porous polymer membrane.

[0009] An alkaline water electrolytic cell according to one aspect of the present disclosure comprises: an anode chamber frame defining an anode chamber; a cathode chamber frame defining a cathode chamber; an anode housed in the anode chamber; a cathode housed in the cathode chamber; and the diaphragm for alkaline water electrolysis disposed between the anode chamber frame and the cathode chamber frame to separate the anode chamber from the cathode chamber.

[0010] A method for producing a diaphragm for alkaline water electrolysis according to one aspect of the present disclosure is a method for producing a diaphragm for alkaline water electrolysis separating an anode chamber and a cathode chamber of an alkaline water electrolytic cell, the method comprising: preparing a porous polymer membrane integrally having a seal region to be sandwiched between cell-constituting members of the alkaline water electrolytic cell, an edge region located on the outer periphery of the seal region, and a separator region located on the inner periphery of the seal region; and forming, in the seal region of the porous polymer membrane by applying pressure or heat, a bulk portion which surrounds the separator region and prevents permeation of an electrolyte through pores in the porous polymer membrane.

[0011] The present disclosure provides a technique for suppressing leakage of electrolyte to the outside of an alkaline water electrolysis cell through a diaphragm in an alkaline water electrolysis cell having a structure in which a porous diaphragm for alkaline water electrolysis protrudes to the outside of the cell.

[0012] Fig. 1 is a cross-sectional view showing the overall configuration of an alkaline water electrolytic cell according to an embodiment of the present disclosure. Fig. 2 is a partially enlarged cross-sectional view of an alkaline water electrolytic cell illustrating in detail the support structure of a diaphragm for alkaline water electrolysis in a cell body. Fig. 3 is a development view of a diaphragm for alkaline water electrolysis. Fig. 4 is a cross-sectional view taken along line IV-IV of the diaphragm for alkaline water electrolysis shown in Fig. 3. Fig. 5 is a modified version of the cross-sectional view of the diaphragm for alkaline water electrolysis shown in Fig. 3, taken along line IV-IV.

[0013] Next, embodiments of the present disclosure will be described with reference to the drawings. First, a schematic configuration of an alkaline water electrolytic cell (hereinafter simply referred to as "electrolytic cell 1") to which a diaphragm for alkaline water electrolysis according to the present disclosure (hereinafter simply referred to as "diaphragm 4") is applied will be described. Note that, hereinafter, unless otherwise specified, "-" indicating a numerical range means "not less than or equal to." In other words, the numerical range "α-β" means "not less than or equal to α and not more than β," and includes both α and β.

[0014] [Schematic Configuration of Electrolytic Cell 1] FIG. 1 is a cross-sectional view showing a schematic configuration of an electrolytic cell 1 according to an embodiment of the present disclosure. The electrolytic cell 1 shown in FIG. 1 includes a cell body 2. The interior of the cell body 2 is separated into an anode chamber 48 and a cathode chamber 49 by a diaphragm 4. The anode chamber 48 and the cathode chamber 49 each have an electrolytic solution supply port and an outlet port for the alkaline solution and gas (hydrogen or oxygen) after electrolysis. An anode assembly 3 is disposed on the anode chamber 48 side of the diaphragm 4 in the electrolytic cell 1. The anode assembly 3 includes a mesh-shaped anode 31 facing the diaphragm 4, an anode conductor plate 32 provided integrally with the anode 31 around the anode 31, and a connection terminal 33 disposed on the anode conductor plate 32. A cathode assembly 7 is disposed on the cathode chamber 49 side of the diaphragm 4 in the electrolytic cell 1. The cathode assembly 7 includes a mesh-like cathode 71 facing the diaphragm 4, a cathode conductor plate 72 arranged away from the cathode 71 on the side opposite the diaphragm 4, a connection terminal 73 provided on the cathode conductor plate 72, and a conductive elastic body 74 provided between the cathode 71 and the cathode conductor plate 72. The elastic body 74 presses the cathode 71 against the diaphragm 4, and the anode 31 and the diaphragm 4, and the diaphragm 4 and the cathode 71 are in close contact with each other.

[0015] The anode 31 is a known electrode that has been used as an anode for alkaline water electrolysis. Known examples of such anodes 31 include those that include a conductive substrate and a catalytic layer coating the surface of the substrate. Examples of the substrate for the anode 31 include nickel, a nickel-based alloy, stainless steel, iron, and nickel-coated iron. Examples of the catalytic layer for the anode 31 include nickel-containing materials such as nickel oxide, metallic nickel, nickel hydroxide, and nickel-cobalt oxide. The cathode 71 is a known electrode that has been used as a cathode for alkaline water electrolysis. Known examples of such cathodes 71 include those that include a conductive substrate and a catalytic layer coating the surface of the substrate. Examples of the conductive substrate for the cathode 71 include nickel, a nickel-based alloy, stainless steel, iron, and nickel-coated iron. Examples of the catalytic layer for the cathode 71 include precious metal oxides, nickel, cobalt, molybdenum, manganese, and oxides thereof.

[0016] When alkaline water is electrolyzed in the electrolytic cell 1 configured as described above, the anode chamber 48 and the cathode chamber 49 are filled with an electrolyte, and a voltage is applied between the anode 31 and the cathode 71. As the electrolyte, for example, an alkaline solution such as potassium hydroxide or sodium hydroxide is used. The concentration of the alkaline solution is not particularly limited, but is preferably about 25-35% by mass. The temperature of the electrolyte is also not particularly limited, but is preferably about 80-100°C. In the cathode chamber 49, electrons are supplied, causing electrolysis of the water in the electrolyte, generating hydrogen gas and hydroxide ions. The hydroxide ions in the cathode chamber 49 permeate the diaphragm 4 and move to the anode chamber 48. In the anode chamber 48, oxygen gas and water are generated from the hydroxide ions.

[0017] [Support Structure of Diaphragm 4] Here, a detailed description will be given of the diaphragm 4 and the support structure of the diaphragm 4. Fig. 2 is an enlarged partial cross-sectional view of the electrolytic cell 1 for explaining in detail the support structure of the diaphragm 4 on the cell body 2.

[0018] 1 and 2 , the cell body 2 of the electrolytic cell 1 is formed by combining an anode chamber frame 21 that defines the anode chamber 48 and a cathode chamber frame 22 that defines the cathode chamber 49. The anode chamber frame 21 and the cathode chamber frame 22 have frame surfaces 21a and 22a that face each other with a diaphragm 4 or the like interposed therebetween. The frame surface 21a of the anode chamber frame 21 and the frame surface 22a of the cathode chamber frame 22 have substantially the same shape, and for example, the frame surfaces 21a and 22a are rectangular or circular strips.

[0019] The anode assembly 3, the diaphragm 4, and the cathode assembly 7 are sandwiched between the frame surface 21a of the anode chamber frame 21 and the frame surface 22a of the cathode chamber frame 22. More specifically, the gasket 24, the anode conductor plate 32 of the anode assembly 3, the diaphragm 4, the spacer 23, the gasket 25, the cathode conductor plate 72 of the cathode assembly 7, and the gasket 26 are arranged in this order between the frame surface 21a of the anode chamber frame 21 and the frame surface 22a of the cathode chamber frame 22.

[0020] The gasket 24 is a sealing material that provides a liquid-tight seal between the anode chamber frame 21 and the anode conductor plate 32. The gasket 25 is a sealing material that provides a liquid-tight seal between the spacer 23 and the cathode conductor plate 72. The gasket 26 is a sealing material that provides a liquid-tight seal between the cathode conductor plate 72 and the cathode chamber frame 22. The gaskets 24, 25, and 26 can be made of a vulcanized or peroxide-crosslinked ethylene-propylene-diene rubber (EPDM) or ethylene-propylene rubber (EPM).

[0021] The spacer 23 separates the diaphragm 4 from the cathode 71. The spacer 23 also cooperates with the anode conductor plate 32 to sandwich the diaphragm 4 in the membrane thickness direction. The spacer 23 can be considered an extension of the cathode chamber frame 22. The diaphragm 4 is pressed in the membrane thickness direction from both sides by the anode conductor plate 32 and the spacer 23. The diaphragm 4 is larger than the spacer 23 and protrudes outside the cell.

[0022] FIG. 3 is a development view of the diaphragm 4, and FIGS. 4 and 5 are cross-sectional views of the diaphragm 4 shown in FIG. 3 taken along line IV-IV. Note that FIGS. 4 and 5 show the diaphragm 4 in a state before it is clamped between the anode chamber frame 21 and the cathode chamber frame 22. As shown in FIG. 3 , the diaphragm 4 comprises a porous polymer membrane 40 integrally having a seal region 41 sandwiched between cell components of the electrolytic cell 1 (specifically, the anode conductor plate 32 and the spacer 23), a marginal region 44 disposed on the outer periphery of the seal region 41, and a separator region 43 disposed on the inner periphery of the seal region 41. The marginal region 44 is a strip-shaped region along the outer edge of the diaphragm 4 and is the portion of the diaphragm 4 exposed to the outside of the cell. The inner peripheral edge of the marginal region 44 corresponds to the outer peripheral edge of the seal region 41. The seal region 41 has substantially the same shape as the frame surface 21 a of the anode chamber frame 21 and the frame surface 22 a of the cathode chamber frame 22. The inner peripheral edge of the seal region 41 corresponds to the outer peripheral edge of the separator region 43. The separator region 43 is a portion of the diaphragm 4 exposed to the inside of the cell and functions as a partition wall separating the anode chamber 48 and the cathode chamber 49. Although the diaphragm 4 shown in Fig. 3 is rectangular, the diaphragm 4 is not limited to a rectangular shape and may have any shape that corresponds to the shapes of the anode chamber frame 21 and the cathode chamber frame 22. For example, if the anode chamber frame 21 and the cathode chamber frame 22 are annular, the diaphragm 4 may be circular.

[0023] As shown in Figures 3 and 4, the diaphragm 4 comprises a porous polymer membrane 40 made of an organic polymer resin and having a large number of pores throughout the entire membrane (excluding a bulk portion 42 described below). Alternatively, as shown in Figures 3 and 5, the diaphragm 4 comprises a porous polymer membrane 40 made of an organic polymer resin and having a large number of pores throughout the entire membrane (excluding a bulk portion 42 described below), and a sheet-like porous support 50 that supports the porous polymer membrane 40. The support 50 may be disposed inside the porous polymer membrane 40, or on either side of the porous polymer membrane 40.

[0024] The organic polymer resin constituting the polymer porous membrane 40 is at least one selected from the group consisting of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, polycarbonate, polytetrafluoroethylene, polypropylene, polyphenylene sulfide, polyketone, polyetheretherketone, polyimide, and polyetherimide. Inorganic particles may be added to the polymer porous membrane 40. The inclusion of inorganic molecules in the diaphragm 4 hydrophilizes the diaphragm 4, thereby suppressing adhesion of oxygen gas and hydrogen gas bubbles to the diaphragm surface. Examples of inorganic particles include metal hydroxides or metal oxides of magnesium, zirconium, titanium, zinc, aluminum, tantalum, etc.; sulfates of calcium, barium, lead, strontium, etc.; nitrides of titanium, zirconium, hafnium, etc.; and carbides of titanium, zirconium, hafnium, etc. The support 50 is a nonwoven fabric, a woven fabric, or a composite fabric of a nonwoven fabric and a woven fabric. The support 50 is formed of at least one type of fiber selected from the group consisting of polyphenylene sulfide, polypropylene, polysulfone, polyethersulfone, polyphenylsulfone, fluorine-based resin, polyketone, polyimide, and polyetherimide.

[0025] In the electrolytic cell 1, the sealing region 41 of the diaphragm 4 is compressed in the thickness direction by being pressed from both sides by the frame-constituting members of the electrolytic cell 1, but not to the extent that the pores of the porous structure are completely crushed. Therefore, the porous structure of the sealing region 41 allows some penetration of the electrolyte into the pores and voids. Therefore, as shown in FIGS. 3 to 5 , the sealing region 41 has a bulk portion 42 located approximately midway between the outer and inner peripheral edges of the sealing region 41 to suppress penetration of the electrolyte into the edge region 44. The bulk portion 42 has a shape that surrounds the separator region 43. Since the outer peripheral shape of the separator region 43 corresponds to the shapes of the frame surfaces 21 a, 22 a of the anode chamber frame 21 and the cathode chamber frame 22, it can also be said that the bulk portion 42 has a shape that corresponds to the frame surfaces 21 a, 22 a of the anode chamber frame 21 and the cathode chamber frame 22. For example, if the frame surfaces 21 a, 22 a are rectangular, the bulk portion 42 is rectangular (frame-shaped). For example, if the frame surfaces 21 a, 22 a are circular, the bulk portion 42 is circular. The diaphragm 4 according to this embodiment has a single bulk portion 42, but may have multiple bulk portions 42, such as double or more.

[0026] The bulk portion 42 of the seal region 41 has a bulk structure, while the portion excluding the bulk portion 42 has a porous structure. Here, a porous structure is a structure with a high porosity having many pores, whereas a "bulk structure" is a structure with a low porosity having almost no or no voids such as pores. The bulk structure of the present disclosure may include a non-porous structure having no voids such as pores, or a porous structure having pores but with an extremely low porosity compared to the portion of the seal region 41 excluding the bulk portion 42. In the bulk portion 42 having such a bulk structure, the permeation path of the electrolyte through the pores and voids is blocked, preventing the electrolyte from permeating from the inner periphery to the outer periphery of the bulk portion 42.

[0027] In the diaphragm 4 according to this embodiment, the large number of pores that existed in the region corresponding to the bulk portion 42 of the polymer porous membrane 40 (or the polymer porous membrane 40 supported by the support 50) are crushed or reduced in size by being crushed or melted, thereby processing the bulk portion 42 into a bulk structure. In this way, the bulk portion 42 has a lower porosity, a higher density, and a more compact structure than other portions of the sealing region 41.

[0028] The porosity of the bulk portion 42 is preferably 0 or close to 0, and is preferably 1 / 10 or less of the porosity of the portion of the sealing region 41 excluding the bulk portion 42. The bulk portion 42 having such a porosity can effectively suppress the penetration of the electrolyte. The porosity is calculated by dividing the total volume by V [m 3 ], the volume of the gap is v [m 3 ], it can be calculated as v / V.

[0029] When voids exist in the bulk portion 42, it is preferable that the voids in the bulk portion 42 are closed pores (also called independent pores). It is also preferable that the bulk portion 42 has low water permeability. For example, the water permeability of the bulk portion 42 can be evaluated by the following water permeability test. That is, a circular piece of the bulk portion 42 having a diameter of 25 mm is cut out as a test membrane, and the test membrane is divided into 2 × 10 ５ When pressurized at 100 Pa and water is forced to pass through for 30 seconds, the bulk portion 42 can be made of a material that does not allow water to pass through, i.e., a material with sufficiently low water permeability.

[0030] The bulk portion 42 is not provided over the entire area of ​​the sealing area 41. The bulk portion 42 is preferably in the form of a line or band having a width W2 that is 0.01 to 1 times the distance W1 between the inner and outer peripheral edges of the sealing area 41. The bulk portion 42 having such a width W2 can prevent tissue around the bulk portion 42 from migrating into the bulk portion 42 and becoming a medium for the electrolyte when the sealing area 41 is sandwiched and compressed between the cell components of the electrolytic cell 1 (specifically, the anode conductive plate 32 and the cathode conductive plate 72).

[0031] The bulk portion 42 preferably has an endless shape that surrounds the separator region 43. This blocks the path of electrolyte permeation from the inner periphery to the outer periphery of the bulk portion 42 around the entire periphery of the separator region 43, thereby suppressing permeation of the electrolyte into the edge region 44. However, the bulk portion 42 is not limited to an endless shape and may be provided at any location where leakage of the electrolyte is to be prevented.

[0032] [Method for manufacturing diaphragm 4] The method for manufacturing the diaphragm 4 having the above configuration includes a step of producing the polymer porous membrane 40 (or the polymer porous membrane 40 supported on the support 50) and a step of forming the bulk portion 42 in the polymer porous membrane 40.

[0033] The diaphragm 4 is a porous membrane for alkaline water electrolysis to which a bulk portion 42 has been added. Therefore, the polymer porous membrane 40 of the diaphragm 4 (or the polymer porous membrane 40 supported on the support 50) can be a polymer porous membrane manufactured by a known method for manufacturing a diaphragm for alkaline water electrolysis. The method for producing the polymer porous membrane 40 is not particularly limited, and for example, a known phase separation method may be employed. In this case, a membrane-forming stock solution is prepared by dissolving the organic polymer resin and additives in an organic solvent, and the membrane-forming stock solution is applied to a substrate to a predetermined thickness to produce a coated sheet. The coated sheet is immersed in a non-solvent to induce phase separation of the membrane-forming stock solution to generate pores, and excess water is then removed to obtain the polymer porous membrane 40. When preparing a polymer porous membrane 40 supported on a support 50, the support 50 may be used instead of the substrate in the above-described process for producing the polymer porous membrane 40.

[0034] The bulk portion 42 can be formed in the polymer porous membrane 40 by applying pressure or heat. A press or the like can be used as a pressure application method. In this case, by applying pressure to the polymer porous membrane 40 using a mold for the bulk portion 42, the pressurized portions of the polymer porous membrane 40 are compressed in the thickness direction, causing the structure to become bulky, thereby forming the bulk portion 42. Furthermore, impulse welding, ultrasonic welding, high-frequency welding, laser welding, hot plate welding, heat pressing, or the like can be used as a heating method. In this case, by heating the polymer porous membrane 40 in accordance with the shape of the reinforcing portion 45, the resin in the heated portions melts and welds, causing the structure to become bulky, thereby forming the bulk portion 42.

[0035] [Summary] The diaphragm 4 for alkaline water electrolysis according to a first aspect of the present disclosure is a diaphragm 4 for alkaline water electrolysis separating an anode chamber 48 and a cathode chamber 49 of an alkaline water electrolytic cell 1, and comprises a porous polymer membrane 40 integrally having a sealing region 41 to be sandwiched between cell-constituting members of the alkaline water electrolytic cell 1, a border region 44 arranged on the outer periphery of the sealing region 41, and a separator region 43 arranged on the inner periphery of the sealing region 41, wherein the sealing region 41 has a shape surrounding the separator region 43 and has a bulk portion 42 that prevents permeation of the electrolyte through pores in the porous polymer membrane 40. The bulk portion 42 has a bulk structure. This bulk structure may be a non-porous structure with no pores, or a porous structure with an extremely low porosity compared to the portion of the sealing region 41 excluding the bulk portion 42.

[0036] With the diaphragm 4 configured as described above, the bulk portion 42 blocks the permeation path of the electrolyte solution that passes through the pores of the porous polymer membrane 40, thereby suppressing the movement of the electrolyte solution toward the edge region 44 that is exposed to the outside of the electrolytic cell 1, i.e., suppressing leakage of the electrolyte solution to the outside of the cell. In this way, the present disclosure can provide a technique for suppressing leakage of the electrolyte solution to the outside of the cell through the diaphragm 4.

[0037] A diaphragm 4 for alkaline water electrolysis according to a second aspect of the present disclosure is the diaphragm 4 for alkaline water electrolysis according to the first aspect, wherein the bulk portion 42 of the seal region 41 has an endless shape surrounding the separator region 43.

[0038] With the diaphragm 4 having the above-described configuration, the bulk portion 42 blocks the permeation path of the electrolyte solution that passes through the pores around the entire periphery of the separator region 43, thereby more effectively suppressing leakage of the electrolyte solution to the outside of the tank through the diaphragm 4.

[0039] A diaphragm 4 for alkaline water electrolysis according to a third aspect of the present disclosure is the diaphragm 4 for alkaline water electrolysis according to the first or second aspect, wherein the bulk portion 42 of the sealing region 41 is in a line or band shape with a width W2 that is 0.01 to 1 times the distance W1 between the inner and outer peripheral edges of the sealing region 41.

[0040] With the diaphragm 4 configured as described above, it is possible to achieve both: the diaphragm 4 is supported in a state of being pressed against the frame-constituting members by the sealing region 41 excluding the bulk portion 42; and the seepage of the electrolyte is suppressed by the bulk portion 42. Furthermore, when the sealing region 41 of the diaphragm 4 is pressed from both sides by the frame-constituting members, the independence of the bulk portion 42 from the other portions of the sealing region 41 is maintained, preventing the establishment of a permeation path for the electrolyte that does not pass through the bulk portion 42.

[0041] An alkaline water electrolytic cell 1 according to a fourth item of the present disclosure comprises: an anode chamber frame 21 that defines an anode chamber 48; a cathode chamber frame 22 that defines a cathode chamber 49; an anode 31 housed in the anode chamber 48; a cathode 71 housed in the cathode chamber 49; and the diaphragm 4 for alkaline water electrolysis according to any one of the first to third items, which is disposed between the anode chamber frame 21 and the cathode chamber frame 22 to separate the anode chamber 48 from the cathode chamber 49.

[0042] According to the electrolytic cell 1 having the above-described configuration, the permeation path of the electrolyte solution through the pores of the polymer porous membrane 40 is blocked by the bulk portion 42, and the movement of the electrolyte solution to the edge region 44 exposed to the outside of the electrolytic cell 1, i.e., leakage of the electrolyte solution to the outside of the cell, is suppressed.

[0043] A fifth aspect of the present disclosure relates to a method for producing a diaphragm 4 for alkaline water electrolysis that separates an anode chamber 48 and a cathode chamber 49 of an alkaline water electrolytic cell 1, the method comprising the steps of: producing a porous polymer membrane 40 that integrally includes a sealing region 41 to be sandwiched between cell-constituting members of the alkaline water electrolytic cell 1, a border region 44 located on the outer periphery of the sealing region 41, and a separator region 43 located on the inner periphery of the sealing region 41; and forming, by applying pressure or heat, a bulk portion 42 in the sealing region 41 of the porous polymer membrane 40. The bulk portion 42 has a shape that surrounds the separator region 43 and prevents permeation of the electrolyte through pores in the porous polymer membrane 40.

[0044] According to the above-described method for manufacturing the diaphragm 4, the diaphragm 4 having the bulk portion 42 that prevents the electrolyte from permeating through the pores of the porous polymer membrane 40 can be easily manufactured.

[0045] The present disclosure has been presented for purposes of illustration and description and is not intended to be limited to the form disclosed herein. For example, in the foregoing Detailed Description, various features of the present disclosure are grouped together in a single embodiment for the purpose of streamlining the disclosure. However, some of the features may also be combined. Furthermore, the features included in the present disclosure may be combined into alternative embodiments, configurations, or aspects other than those discussed above.

[0046] 1: alkaline water electrolysis cell 4: alkaline water electrolysis diaphragm 21: anode chamber frame 22: cathode chamber frame 31: anode 40: polymer porous membrane 41: seal region 42: bulk portion 43: separator region 44: edge region 48: anode chamber 49: cathode chamber 71: cathode

Claims

1. A diaphragm for alkaline water electrolysis separating an anode chamber and a cathode chamber of an alkaline water electrolytic cell, comprising a porous polymer membrane integrally having: a seal area to be sandwiched between cell-constituting members of the alkaline water electrolytic cell; an edge area located on the outer periphery of the seal area; and a separator area located on the inner periphery of the seal area, wherein the seal area has a shape that surrounds the separator area and has a bulk part that prevents permeation of the electrolyte through pores in the porous polymer membrane.

2. The diaphragm for alkaline water electrolysis according to claim 1, wherein the bulk portion of the seal region has an endless shape surrounding the separator region.

3. The diaphragm for alkaline water electrolysis according to claim 1 or 2, wherein the bulk portion of the seal region is in the shape of a line or a band having a width that is 0.01 to 1 times the distance between the inner circumferential edge and the outer circumferential edge of the seal region.

4. An alkaline water electrolytic cell comprising: an anode chamber frame defining an anode chamber; a cathode chamber frame defining a cathode chamber; an anode housed in the anode chamber; a cathode housed in the cathode chamber; and the diaphragm for alkaline water electrolysis according to claim 1, disposed between the anode chamber frame and the cathode chamber frame to separate the anode chamber from the cathode chamber.

5. A method for producing a diaphragm for alkaline water electrolysis separating an anode chamber and a cathode chamber of an alkaline water electrolytic cell, comprising: a step of producing a porous polymer membrane integrally having a seal area to be sandwiched between cell-constituting members in the alkaline water electrolytic cell, an edge area located on the outer periphery of the seal area, and a separator area located on the inner periphery of the seal area; and a step of forming, in the seal area of ​​the porous polymer membrane, by applying pressure or heat, a bulk part which surrounds the separator area and prevents permeation of an electrolyte through pores in the porous polymer membrane.

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