Alkaline water electrolyzer

Abstract

An alkaline water electrolyzer comprises: an anode side frame defining an anode chamber; a cathode side frame defining a cathode chamber; an ion-permeable diaphragm disposed between the anode side frame and the cathode side frame, dividing the anode chamber and the cathode chamber; a gasket clamped by the anode side frame and the cathode side frame, retaining the peripheral edge of the diaphragm; an anode disposed within the anode chamber without being retained by the gasket; a cathode disposed within the cathode chamber without being retained by the gasket; and a first elastic body disposed within the anode chamber and having conductivity, wherein the anode is a flexible first porous plate, and is disposed between the diaphragm and the first elastic body, and is pressed toward the cathode by the first elastic body.

Description

Technical Field

[0001] The present invention relates to an electrolytic cell for electrolysis of alkaline water. Background Art

[0002] As a method for producing hydrogen and oxygen, alkaline water electrolysis is known. In the alkaline water electrolysis, water is electrolyzed by using an alkaline aqueous solution (alkaline water) in which an alkali metal hydroxide (such as NaOH, KOH, etc.) is dissolved as an electrolyte, thereby generating hydrogen from the cathode and oxygen from the anode. As an electrolytic cell for alkaline water electrolysis, the following electrolytic cell is known, which has an anode chamber and a cathode chamber divided by an ion-permeable diaphragm, an anode is respectively arranged in the anode chamber and a cathode is respectively arranged in the cathode chamber. In addition, in order to reduce energy loss, an electrolytic cell having a zero-gap structure (zero-gap electrolytic cell) in which the anode and the cathode are respectively maintained in direct contact with the diaphragm has been proposed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-262387

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-104090

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2013-108150

[0008] Patent Document 4: International Publication No. 2018 / 139616

[0009] Patent Document 5: Japanese Patent Application Laid-Open No. 2015-117407

[0010] Patent Document 6: International Publication No. 2013 / 191140

[0011] Patent Document 7: Japanese Patent No. 4453973

[0012] Patent Document 8: Japanese Patent No. 6093351

[0013] Patent Document 9: Japanese Patent Application Laid-Open No. 2015-117417

[0014] Patent Document 10: International Publication No. 2019 / 111832 Summary of the Invention

[0015] Problems to be solved by the invention

[0016] Figure 1FIG1 is a partial cross-sectional view schematically illustrating a conventional zero-gap alkaline water electrolysis cell 900 according to one embodiment. The zero-gap electrolytic cell 900 comprises: electrode chamber units 910, 910, ..., which have a conductive partition wall 911 and a flange portion 912 separating the anode chamber A and the cathode chamber C; an ion-permeable diaphragm 920, which is arranged between adjacent electrode chamber units 910, 910; gaskets 930, 930, which are arranged between the diaphragm 920 and the flange portion 912 of the electrode chamber unit 910 and clamp the peripheral portion of the diaphragm 920; a rigid anode 940, which is retained by conductive ribs 913, 913, ... set upright from the partition wall 911 of one electrode chamber unit; and a soft cathode 970, which is retained by a collector 950 and a conductive elastomer 960 arranged in contact with the collector 950, and the collector 950 is retained by conductive ribs 914, 914, ... set upright from the partition wall 911 of another electrode chamber unit. The periphery of cathode 970 and the periphery of conductive elastomer 960 are fixed to the periphery of current collector 950. In zero-gap electrolytic cell 900, conductive elastomer 960 presses flexible cathode 970 toward diaphragm 920 and anode 940, thereby sandwiching diaphragm 920 between adjacent cathodes 970 and anodes 940. As a result, diaphragm 920 and anode 940, as well as diaphragm 920 and cathode 970, are in direct contact (i.e., zero gap), thereby reducing the solution resistance between anode 940 and cathode 970 and reducing energy loss.

[0017] In the previous zero-gap alkaline water electrolyzer 900, the conductive elastomer 960 presses the soft cathode 970 toward the diaphragm 920 and the rigid anode 940, and the rigid anode 940 is welded to the conductive rib 913, and the conductive rib 913 is welded to the partition wall 911. This structure is reasonable in the alkaline water electrolysis process in which the pressure on the cathode chamber side of the hydrogen production is maintained higher than the pressure on the anode chamber side of the oxygen production. That is, the diaphragm 920 as the ion permeability of the alkaline water electrolyzer is usually replaced by a cheap porous membrane instead of the expensive ion exchange membrane used in the electrolyzer of the alkali metal salt. Unlike the ion exchange membrane, the diaphragm 920 as a porous membrane also has a certain degree of permeability for gas. Therefore, from the perspective of improving the purity of the hydrogen recovered from the cathode chamber, it is advantageous to maintain the pressure in the cathode chamber of the hydrogen production higher than the pressure in the anode chamber of the oxygen production to carry out electrolysis. When the pressure in the cathode chamber is higher than the pressure in the anode chamber, the diaphragm 920 is pressed toward the anode 940 due to the pressure difference (pressure differential) between the two chambers. As in the above-mentioned alkaline water electrolyzer 900, in a structure in which the conductive elastomer 960 presses the soft cathode 970 toward the rigid anode 940, the direction in which the conductive elastomer 960 presses the cathode 970 is the same as the direction in which the pressure difference between the two chambers presses the diaphragm 920. Therefore, even if the reaction force of the conductive elastomer 960 is low, the zero gap state can be stably maintained. This is also beneficial in terms of extending the renewal interval of the elastomer 960 and reducing the wear of the diaphragm 920 caused by pressure fluctuations during operation.

[0018] However, oxygen is generated in the anode 940 of the alkaline water electrolysis cell, so bound electrons flow out of the anode 940, and the anode 940 is placed under oxidizing conditions. The anode 940 generally includes a conductive substrate and a catalyst supported on the surface of the substrate. In the anode 940 placed under oxidizing conditions as described above, the catalyst and the conductive substrate are easily ionized or oxidized, so the catalyst is easily detached from the electrode surface. As a result, the anode 940 tends to reach the end of its service life earlier than the cathode 970. The anode 940 that has reached the end of its service life needs to be replaced with a new one. In order to replace the anode 940 in the electrolysis cell 900, it is necessary to (1) mechanically separate the anode 940 from the conductive rib 913 (for example, by melting, etc.), (2) adjust the height of the end of the conductive rib 913 (for example, by grinding, etc.), and (3) weld the new anode 940 to the conductive rib 913. This replacement operation requires dedicated equipment, making it difficult to replace the anode 940 at the site where the electrolysis cell is installed and operated. Therefore, when the life of the anode 940 expires, the electrode chamber unit 910 is sent to a factory that can replace the anode 940. After the anode 940 is replaced at the factory, the electrode chamber unit 910 that has completed the anode 940 replacement operation is returned from the factory to the electrolytic cell installation and operation site, either in this state or with the elastic body 960 and cathode 970 further installed. Thus, in conventional zero-gap alkaline water electrolyzers, the anode replacement operation requires a high cost.

[0019] In this way, the rigid anode is generally fixed to the conductive rib by welding, etc., so labor and cost are required in the replacement of the anode. From the viewpoint of easy disassembly of the anode, although it is also possible to set an electrolytic cell without conductive ribs, the conductive ribs not only play the role of electrically connecting the electrode to the partition wall, but also play other important roles in ensuring space for the circulation of the electrode liquid and gas in the electrode chamber. In particular, in a zero-gap electrolytic cell, the gas generated at the electrode cannot escape to the diaphragm side of the electrode, so it will escape to the partition wall side of the electrode. By arranging a space with a certain size that can be provided for the gas generated at the electrode to escape behind the electrode (and a conductive elastomer, if any) (i.e., the partition wall side), the time that the gas generated at the electrode stays near the electrode can be shortened, so the gas resistance can be reduced and the electrolysis voltage can be reduced. Therefore, it is also important to set conductive ribs in the anode chamber from the viewpoint of reducing energy loss.

[0020] An object of the present invention is to provide a zero-gap alkaline water electrolysis cell in which the anode can be easily replaced, particularly in a case where conductive ribs are provided in the anode chamber.

[0021] Solutions for solving problems

[0022] The present invention includes the following technical solutions [1] to [9].

[0023] [1] An alkaline water electrolyzer comprising:

[0024] an anode side frame defining an anode chamber;

[0025] a cathode side frame defining a cathode chamber;

[0026] an ion-permeable diaphragm disposed between the anode-side frame and the cathode-side frame to divide the anode chamber and the cathode chamber;

[0027] a gasket sandwiched between the anode-side frame and the cathode-side frame, the gasket holding the peripheral edge of the diaphragm;

[0028] an anode disposed inside the anode chamber without being held by the gasket;

[0029] a cathode disposed inside the cathode chamber without being held by the gasket; and

[0030] a first elastic body, which is disposed inside the anode chamber and has electrical conductivity;

[0031] The anode is a flexible first porous plate,

[0032] The anode is disposed between the separator and the first elastic body, and is pressed toward the cathode by the first elastic body.

[0033] [2] The alkaline water electrolyzer according to [1], wherein:

[0034] The anode chamber comprises:

[0035] at least one first conductive rib provided to protrude from the inner wall of the anode side frame; and

[0036] a conductive first current collector held by the first conductive rib,

[0037] The first elastic body is supported by the first current collector.

[0038] [3] The alkaline water electrolyzer according to [1] or [2], wherein:

[0039] The alkaline water electrolyzer further comprises a first rigid current collector, which is arranged in contact with the anode and has conductivity.

[0040] The first rigid current collector is arranged between the anode and the first elastic body.

[0041] The anode is supported by the first rigid current collector.

[0042] [4] The alkaline water electrolyzer according to any one of [1] to [3], wherein

[0043] The cathode is a rigid porous plate.

[0044] [5] The alkaline water electrolyzer according to [4], wherein:

[0045] The cathode chamber includes at least one second conductive rib protruding from the inner wall of the cathode side frame.

[0046] The cathode is held by the second conductive rib.

[0047] [6] The alkaline water electrolyzer according to any one of [1] to [3], wherein

[0048] The alkaline water electrolyzer further comprises a second elastic body, which is disposed inside the cathode chamber and has electrical conductivity.

[0049] The cathode is a flexible second porous plate,

[0050] The cathode is disposed between the separator and the second elastic body, and is pressed toward the anode by the second elastic body.

[0051] [7] The alkaline water electrolyzer according to [6], wherein:

[0052] The cathode chamber comprises:

[0053] at least one second conductive rib protruding from the inner wall of the cathode side frame; and

[0054] a conductive second current collector held by the second conductive rib,

[0055] The second elastic body is supported by the second current collector.

[0056] [8] The alkaline water electrolyzer according to [6] or [7], wherein:

[0057] The alkaline water electrolyzer further comprises a second rigid current collector, which is arranged in contact with the cathode and has conductivity.

[0058] The second rigid current collector is arranged between the cathode and the second elastic body.

[0059] The cathode is supported by the second rigid current collector.

[0060] [9] A method for replacing an electrode in an alkaline water electrolysis cell, the method being a method for replacing the anode in the alkaline water electrolysis cell according to any one of [1] to [8], the method comprising:

[0061] separating the anode side frame from the gasket;

[0062] separating the separator from the anode;

[0063] removing the anode from the anode chamber; and

[0064] The alkaline water electrolyzer was assembled using a new anode in place of the anode.

[0065] Effects of the Invention

[0066] In the alkaline water electrolyzer of the present invention, a flexible anode is pressed toward the cathode by a conductive elastomer, thereby achieving a zero-gap structure. Therefore, the alkaline water electrolyzer of the present invention allows for easy replacement of the anode, particularly when conductive ribs are provided within the anode chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 1 is a cross-sectional view schematically illustrating a conventional zero-gap electrolytic cell 900 according to one embodiment.

[0068] Figure 2 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 100 according to one embodiment of the present invention.

[0069] Figure 3 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 200 according to another embodiment of the present invention.

[0070] Figure 4 FIG. 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 300 according to another embodiment of the present invention.

[0071] Figure 5 FIG. 4 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 400 according to another embodiment of the present invention.

[0072] Figure 6 FIG. 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 500 according to another embodiment of the present invention. DETAILED DESCRIPTION

[0073] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to these embodiments. In addition, the drawings may not necessarily reflect accurate dimensions. In addition, in the drawings, some of the figure marks are sometimes omitted. In this specification, regarding the numerical values A and B, unless otherwise specified, expressions such as "A to B" mean "greater than or equal to A and less than or equal to B". In the case where only the numerical value B is accompanied by a unit in the expression, the unit is also applied to the numerical value A. In addition, regarding the words "or" and "or", unless otherwise specified, they mean logical OR. In addition, regarding elements E1 and E2, expressions such as "E1 and / or E2" mean "E1 or E2, or a combination thereof", and regarding elements E1, ..., E N (N is an integer greater than 3), "E1, ..., E N-1 , and / or E N "This expression means "E1, ..., E N-1 , or E N , or a combination thereof".

[0074] Figure 2 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 100 (hereinafter sometimes referred to as “electrolysis cell 100”) according to one embodiment. Figure 2 As shown, the electrolytic cell 100 includes: a conductive anode-side frame 51 defining an anode chamber A; a conductive cathode-side frame 52 defining a cathode chamber C; an ion-permeable diaphragm 10 disposed between the anode-side frame 51 and the cathode-side frame 52 to separate the anode chamber A from the cathode chamber C; gaskets 30, 30 (hereinafter sometimes simply referred to as "gasket 30") sandwiched between the anode-side frame 51 and the cathode-side frame 52 to hold the peripheral edge of the diaphragm 10; an anode 40 disposed within the anode chamber A without being held by the gasket 30; and a cathode 21 disposed within the cathode chamber C without being held by the gasket 30. In the electrolytic cell 100, the anode 40 is a flexible porous plate (a first porous plate), and the cathode 21 is a rigid porous plate (a second porous plate). The electrolytic cell 100 further includes: at least one conductive rib (first conductive rib) 61, 61, ... (hereinafter sometimes referred to as "conductive rib 61") provided so as to protrude from the inner wall of the anode-side frame 51; a current collector (first current collector) 71 held by the conductive rib 61; and an elastic body (first elastic body) 81 held by the current collector 71 and having conductivity, with the anode 40 being pressed toward the cathode 21 by the elastic body 81. The electrolytic cell 100 further includes at least one conductive rib (second conductive rib) 62, 62, ... (hereinafter sometimes referred to as "conductive rib 62") provided so as to protrude from the inner wall of the cathode-side frame 52, and the cathode 21 is held by the conductive rib 62.

[0075] As the anode side frame 51 and the cathode side frame 52, any known frame used in alkaline water electrolyzers can be used without particular limitation, as long as they can respectively define the anode chamber A and the cathode chamber C. The anode side frame 51 includes a conductive partition wall 51a and a flange portion 51b that is watertightly bonded to the entire periphery of the partition wall 51a. Similarly, the cathode side frame 52 also includes a conductive partition wall 52a and a flange portion 52b that is watertightly bonded to the entire periphery of the partition wall 52a. The partition walls 51a and 52a separate adjacent electrolysis cells and electrically connect adjacent electrolysis cells in series. The flange portion 51b, together with the partition wall 51a, the diaphragm 10, and the gasket 30, defines the anode chamber A. The flange portion 52b, together with the partition wall 52a, the diaphragm 10, and the gasket 30, defines the cathode chamber C. The flange portions 51b and 52b have a shape corresponding to the gasket 30. That is, when the gasket 30 is clamped by the anode side frame 51 and the cathode side frame 52, the flange portion 51b of the anode side frame 51 and the flange portion 52b of the cathode side frame 52 are in contact with the gaskets 30, 30 without a gap. Figure 2 Although not shown, flange portion 51b includes an anolyte supply path for supplying anolyte to anode chamber A and an anolyte recovery path for recovering anolyte and gas generated at the anode from anolyte A. Furthermore, flange portion 52b includes a catholyte supply path for supplying catholyte to cathode chamber C and a catholyte recovery path for recovering catholyte and gas generated at the cathode from cathode chamber C. The materials for partition walls 51a and 52a can be any alkali-resistant, rigid, conductive material without particular limitation. Examples of such materials include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and nickel-plated metals thereof. As the material of the flange portions 51b and 52b, a rigid material having alkali resistance can be used without particular limitation, and examples of such materials include single metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metal materials on which nickel plating is applied; and non-metallic materials such as reinforced plastics. The partition wall 51a of the anode side frame 51 and the flange portion 51b can be joined by welding, bonding, etc., or they can be formed integrally from the same material. Similarly, the partition wall 52a of the cathode side frame 52 and the flange portion 52b can be joined by welding, bonding, etc., or they can be formed integrally from the same material. In addition, Figure 2 Only a single electrolytic unit (electrolytic cell 100) is shown in FIG. 1 , but the flange portion 51b of the anode side frame 51 may also extend toward the opposite side of the partition wall 51a ( Figure 2The flange portion 52b of the cathode side frame 52 extends to the opposite side of the partition wall 52a ( Figure 2 It extends to the left side of the paper in FIG. 5 and defines, together with the partition wall 52 a , the anode chambers of adjacent electrolytic units.

[0076] As the diaphragm 10, the known ion permeable diaphragm used in the zero-gap electrolyzer for alkaline water electrolysis can be used without particular limitation. It is desirable that the gas permeability of the diaphragm 10 is low, the electrical conductivity is small, and the strength is high. As examples of the diaphragm 10, porous diaphragms such as a porous membrane consisting of asbestos and / or modified asbestos, a porous diaphragm using a polysulfone polymer, a cloth using polyphenylene sulfide fiber, a fluorine-based porous membrane, a porous membrane using a mixed material comprising an inorganic material and an organic material can be cited. In addition, in addition to these porous diaphragms, ion exchange membranes such as a fluorine-based ion exchange membrane can also be used as the diaphragm 10.

[0077] As the gasket 30, any gasket having electrical insulation properties that can be used in an electrolytic cell for alkaline water electrolysis can be used without particular limitation. Figure 2 : The cross section of the gasket 30 is shown in FIG. The gasket 30 has a flat shape and clamps the peripheral edge of the diaphragm 10. On the other hand, the gasket 30 is clamped between the flange 51b of the anode side frame 51 and the flange 52b of the cathode side frame 52. The gasket 30 is preferably formed by an elastomer with alkali resistance. Examples of materials for the gasket 30 include natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), silicone rubber (SR), ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), fluororubber (FR), isobutylene-isoprene rubber (IIR), polyurethane rubber (UR), chlorosulfonated polyethylene rubber (CSM) and other elastomers. In addition, when using a gasket material that does not have alkali resistance, a layer of a material with alkali resistance can be provided on the surface of the gasket material by covering it.

[0078] As the first conductive ribs 61 and the second conductive ribs 62, any known conductive ribs used in alkaline water electrolysis cells can be used without particular limitation. In the electrolytic cell 100, the first conductive ribs 61 are disposed upright from the partition wall 51a of the anode side frame 51, and the second conductive ribs 62 are disposed upright from the partition wall 52a of the cathode side frame 52. As long as the first conductive ribs 61 can secure and retain the first current collector 71 relative to the anode side frame 51, the shape, number, and arrangement of the first conductive ribs 61 are not particularly limited. Furthermore, as long as the second conductive ribs 62 can secure and retain the cathode 21 relative to the cathode side frame 52, the shape, number, and arrangement of the second conductive ribs 62 are also not particularly limited. As the material of the first conductive rib 61 and the second conductive rib 62, a rigid conductive material with alkali resistance can be used without particular restriction. Examples of such materials include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals that have been nickel-plated.

[0079] As the current collector (first current collector) 71, any known current collector used in alkaline water electrolysis cells can be used without particular limitation. For example, a porous metal mesh, perforated metal, or mesh made of a rigid, alkaline-resistant conductive material can be preferably used. Examples of materials for the current collector 71 include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals plated with nickel. The current collector 71 can be secured to the conductive ribs 61 using known methods such as welding and pinning.

[0080] As the elastic body (first elastic body) 81, any known conductive elastic body used in alkaline water electrolyzers can be used without particular limitation. For example, an elastic pad, coil spring, or leaf spring formed from a collection of metal wires made of an alkali-resistant conductive material can be preferably used. Examples of materials for the current collector 81 include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and nickel-plated metals. To secure the elastic body 81 to the current collector 71, known methods such as welding and pinning can be used without particular limitation.

[0081] The anode 40 is an anode for generating oxygen. The anode 40 generally comprises a conductive substrate and a catalyst layer covering the surface of the substrate. The catalyst layer is preferably porous. As the conductive substrate of the anode 40, for example, nickel, iron, vanadium, molybdenum, copper, silver, manganese, platinum group elements, graphite, or chromium or a combination thereof can be used. In the anode 40, a conductive substrate composed of nickel can be preferably used. The catalyst layer contains nickel as an element. The catalyst layer preferably contains nickel oxide, metallic nickel, or nickel hydroxide or a combination thereof, and may also contain an alloy of nickel and one or more other metals. The catalyst layer is particularly preferably composed of metallic nickel. In addition, the catalyst layer may also contain chromium, molybdenum, cobalt, tantalum, zirconium, aluminum, zinc, platinum group elements, or rare earth elements or a combination thereof. Rhodium, palladium, iridium, or ruthenium or a combination thereof may also be further loaded on the surface of the catalyst layer as an additional catalyst.

[0082] The anode 40 is a flexible porous plate (first porous plate). As the anode 40 having a flexible porous plate, a porous plate having a flexible conductive substrate (e.g., a metal mesh woven (or braided) from metal wires, a thin perforated metal, etc.) and the above-mentioned catalyst layer can be used. The area of one hole of the anode 40 having a flexible porous plate is preferably 0.05 to 2.0 mm. 2 , more preferably 0.1 to 0.5 mm 2 . The porosity of the anode 40, which is a flexible porous plate, is preferably 20% or more relative to the area of the current-carrying surface, and more preferably 20 to 50%. The bending flexibility of the anode 40, which is a flexible porous plate, is preferably 0.05 mm / g or more, and more preferably 0.1 to 0.8 mm / g. In addition, in this specification, bending flexibility refers to a value obtained by dividing the deflection amplitude (mm) of a square sample of 10 mm in length and 10 mm in width, when a certain load is applied downward to the other side opposite to the fixed side, by the load (g). That is, bending flexibility is a parameter that represents a property opposite to bending rigidity. Bending flexibility can be adjusted according to the material and thickness of the porous plate, and for a metal mesh, it can also be adjusted according to the weaving method (or braiding method) of the metal wire constituting the metal mesh.

[0083] The peripheral edge of the anode 40 is held by the current collector 71, the elastic body 81, and / or the flange 51b of the anode side frame 51. When the peripheral edge of the anode 40 is held by the current collector 71, the elastic body 81, and / or the flange 51b of the anode side frame 51, a known method such as welding, pinning, bolting, or folding into the current collector 71 (i.e., hooking the valley formed by bending the peripheral edge of the anode 40 on the peripheral edge of the current collector 71) can be adopted without particular limitation.

[0084] The cathode 21 is a cathode for generating hydrogen. The cathode 21 typically comprises a conductive substrate and a catalyst layer covering the surface of the substrate. Examples of the conductive substrate of the cathode 21 include nickel, a nickel alloy, stainless steel, mild steel, a nickel alloy, or a substrate obtained by plating the surface of stainless steel or mild steel with nickel. The catalyst layer of the cathode 21 may preferably be a noble metal oxide, nickel, cobalt, molybdenum, or manganese, or oxides thereof, or a coating composed of a noble metal oxide.

[0085] The cathode 21 is a rigid porous plate. A porous plate comprising a rigid conductive substrate (e.g., expanded metal) and the catalyst layer can be used as the rigid porous plate. The cathode 21 can be secured to the conductive ribs 62 using any known method, such as welding, pinning, or bolting, without particular limitation.

[0086] In the electrolytic cell 100, the anode 40 is disposed between the diaphragm 10 and the first elastic body 81 and is pressed toward the cathode 21 by the first elastic body 81, thereby achieving a zero-gap structure. In the electrolytic cell 100, the process of replacing an anode 40 that has reached the end of its life with a new anode 40 includes: (1) separating the anode side frame 51 from the gasket 30; (2) separating the diaphragm 10 from the anode 40; (3) removing the anode 40 from the anode chamber A; and (4) assembling the electrolytic cell 100 using the new anode 40 in place of the removed anode 40. In the electrolytic cell 100, the removal of the anode 40 in (3) and the assembly of the new anode 40 in (4) are easy. In addition, in the assembled electrolytic cell 100, the position of the anode 40 is automatically adjusted by the first elastic body 81. Therefore, when assembling a new anode 40, there is no need for complicated operations (such as aligning the height of the end of the conductive rib 913 by grinding, etc.) as in the conventional zero-gap type alkaline water electrolytic cell (see Figure 1 Therefore, the electrolytic cell 100 can easily replace the anode 40 .

[0087] In the above description of the present invention, an alkaline water electrolysis cell 100 is used as an example in which the cathode 21 of the rigid porous plate is held by the conductive ribs 62. However, the present invention is not limited to this embodiment. For example, an alkaline water electrolysis cell may also be used in which the cathode of the rigid porous plate is pressed toward the anode by a conductive second elastic body. Figure 3 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 200 (hereinafter sometimes referred to as “electrolysis cell 200”) according to another embodiment of the present invention. Figure 3 Sometimes, Figure 2 Elements that are identical to those represented in Figure 2 The same reference numerals as in the figure are used and their descriptions are omitted. Figure 3As shown, the electrolytic cell 200 includes: a conductive anode-side frame 51 defining an anode chamber A; a conductive cathode-side frame 52 defining a cathode chamber C; an ion-permeable diaphragm 10 disposed between the anode-side frame 51 and the cathode-side frame 52 to separate the anode chamber A from the cathode chamber C; gaskets 30, 30 sandwiched between the anode-side frame 51 and the cathode-side frame 52 to retain the peripheral edge of the diaphragm 10; an anode 40 disposed within the anode chamber A without being retained by the gasket 30; and a cathode 20 disposed within the cathode chamber C without being retained by the gasket 30. In the electrolytic cell 200, the anode 40 is a flexible first porous plate, and the cathode 20 is a flexible second porous plate. The electrolytic cell 200 further includes: at least one conductive rib (first conductive rib) 61 provided so as to protrude from the inner wall of the anode-side frame 51; a current collector (first current collector) 71 held by the conductive rib 61; and an elastic body (first elastic body) 81 held by the current collector 71 and having conductivity, with the anode 40 being pressed toward the cathode 20 by the elastic body 81. The electrolytic cell 200 further includes: a conductive rib (second conductive rib) 62 provided so as to protrude from the inner wall of the cathode-side frame 52; a current collector (second current collector) 72 held by the conductive rib 62; and an elastic body (second elastic body) 82 held by the current collector 72 and having conductivity, with the cathode 20 being pressed toward the anode 40 by the elastic body 82.

[0088] In the electrolytic cell 200, as the second conductive rib 62, the same conductive rib as that in the electrolytic cell 100 ( Figure 2 ) are similar to the second conductive ribs 62 described above. In the electrolytic cell 200, the second conductive ribs 62 are provided upright from the partition wall 52a of the cathode-side frame. The shape, number, and arrangement of the second conductive ribs 62 are not particularly limited as long as the second conductive ribs 62 can secure and retain the second current collector 72 relative to the cathode-side frame 52.

[0089] In the electrolytic cell 200, the peripheral edge of the anode 40 is held by the current collector 71, the elastic body 81, and / or the flange 51b of the anode side frame 51. When holding the peripheral edge of the anode 40 to the current collector 71, the elastic body 81, and / or the flange 51b of the anode side frame 51, any known method such as welding, pinning, bolting, or folding into the current collector 71 (i.e., hooking the valley formed by bending the peripheral edge of the anode 40 onto the peripheral edge of the current collector 71) can be employed without particular limitation.

[0090] The cathode 20 is a flexible porous plate (second porous plate) and is different from the cathode 21 (see Figure 2As the cathode 20 having a flexible porous plate, a porous plate having a flexible conductive substrate (for example, a metal mesh woven (or braided) by metal wires, a thin perforated metal, etc.) and the above-mentioned catalyst layer can be used. The area of one hole of the cathode 20 having a flexible porous plate is preferably 0.05 to 2.0 mm 2 , more preferably 0.1 to 0.5 mm 2 The cathode 20, which is a flexible porous plate, preferably has an opening ratio of 20% or more, more preferably 20 to 50%, relative to the area of the current-carrying surface. The cathode 20, which is a flexible porous plate, preferably has a bending flexibility of 0.05 mm / g or more, more preferably 0.1 to 0.8 mm / g.

[0091] In the electrolytic cell 200, the peripheral edge of the cathode 20 is held by the current collector 72, the elastic body 82, and / or the flange 52b of the cathode side frame 52. When holding the peripheral edge of the cathode 20 to the current collector 72, the elastic body 82, and / or the flange 52b of the cathode side frame 52, any known method such as welding, pinning, bolting, or folding into the current collector 72 (i.e., hooking the valley formed by bending the peripheral edge of the cathode 20 to the peripheral edge of the current collector 72) can be employed without particular limitation.

[0092] As the current collector (second current collector) 72, any known current collector used in alkaline water electrolysis cells can be used without particular limitation. For example, a porous metal mesh or perforated metal made of a rigid, alkaline-resistant conductive material can be preferably used. Examples of materials for the current collector 72 include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and nickel-plated metals thereof. The current collector 72 can be secured to the conductive ribs 62 using known methods such as welding and pinning.

[0093] As the elastic body (second elastic body) 82, any known conductive elastic body used in alkaline water electrolyzers can be used without particular limitation. For example, an elastic pad, coil spring, or leaf spring formed from a collection of metal wires made of an alkali-resistant conductive material can be preferably used. Examples of materials for the elastic body 82 include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals plated with nickel. To secure the elastic body 82 to the current collector 72, known methods such as welding, pinning, and bolting can be used without particular limitation.

[0094] In the electrolytic cell 200, the anode 40 is disposed between the diaphragm 10 and the first elastic body 81 and is pressed toward the cathode 20 by the first elastic body 81. Furthermore, the cathode 20 is disposed between the diaphragm 10 and the second elastic body 82 and is pressed toward the anode 40 by the second elastic body 82, thereby achieving a zero-gap structure. In the electrolytic cell 200, the process of replacing an anode 40 that has reached the end of its life with a new anode 40 includes: (1) separating the anode side frame 51 from the gasket 30; (2) separating the diaphragm 10 from the anode 40; (3) removing the anode 40 from the anode chamber A; and (4) assembling the electrolytic cell 200 using the new anode 40 in place of the removed anode 40. In the electrolytic cell 200, the removal of the anode 40 in (3) and the assembly of the new anode 40 in (4) are easy. Furthermore, in the assembled electrolytic cell 200, the positions of the anode 40 and the cathode 20 are automatically adjusted by the first elastic body 81 and the second elastic body 82. Therefore, when assembling a new anode 40, there is no need for complicated operations (such as aligning the height of the ends of the conductive ribs 913 by grinding, etc.) as in the conventional zero-gap type alkaline water electrolytic cell. Figure 1 Therefore, the anode 40 can be easily replaced in the electrolytic cell 200 as well.

[0095] In the above description of the present invention, the alkaline water electrolysis cells 100 and 200 are exemplified as being configured such that the anode 40 is in direct contact with the first elastic body 81, and the first elastic body 81 directly presses the anode 40 toward the cathode 20, 21. However, the present invention is not limited to this configuration. For example, an alkaline water electrolysis cell may also be configured such that a conductive rigid current collector is further provided between the anode and the first elastic body. Figure 4 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 300 (hereinafter sometimes referred to as “electrolysis cell 300”) according to another embodiment. Figure 4 Sometimes, Figures 2 and 3 The element annotation represented in Figures 2 and 3 The same reference numerals as in the figure are used and their descriptions are omitted. Figure 4As shown, the electrolytic cell 300 includes: a conductive anode-side frame 51 defining an anode chamber A; a conductive cathode-side frame 52 defining a cathode chamber C; an ion-permeable diaphragm 10 disposed between the anode-side frame 51 and the cathode-side frame 52 to separate the anode chamber A from the cathode chamber C; gaskets 30, 30 sandwiched between the anode-side frame 51 and the cathode-side frame 52 to retain the peripheral edge of the diaphragm 10; an anode 40 disposed within the anode chamber A without being retained by the gasket 30; and a cathode 20 disposed within the cathode chamber C without being retained by the gasket 30. In the electrolytic cell 300, the anode 40 is a flexible first porous plate, and the cathode 20 is a flexible second porous plate. The electrolytic cell 300 further includes: at least one conductive rib (first conductive rib) 61 provided so as to protrude from the inner wall of the anode-side frame 51; a current collector (first current collector) 71 held by the conductive rib 61; an elastic body (first elastic body) 81 held by the current collector 71 and having conductivity; and a rigid current collector 91 disposed between the elastic body 81 and the anode 40 and having conductivity, with the anode 40 being pressed toward the cathode 20 by the elastic body 81 via the rigid current collector 91. That is, in the electrolytic cell 300, the rigid current collector 91 is disposed so as to sandwich the anode 40 between the rigid current collector 91 and the separator 10, and the anode 40 is supported by the rigid current collector 91. The electrolytic cell 300 also includes: at least one conductive rib (second conductive rib) 62, which is arranged to protrude from the inner wall of the cathode side frame 52; a collector (second collector) 72, which is retained by the conductive rib 62; and an elastomer (second elastomer) 82, which is retained by the collector 72 and has conductivity, and the cathode 20 is pressed toward the anode 40 by the elastomer 82.

[0096] As the rigid current collector 91, a rigid current collector having conductivity can be used. For example, a porous metal mesh, perforated metal, etc. made of a rigid conductive material having alkali resistance can be preferably used. Examples of materials for the rigid current collector 91 include elemental metals such as nickel and iron; stainless steels such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals plated with nickel. The rigid current collector 91 may or may not be retained on the elastomer 81. When retaining the rigid current collector 91 on the elastomer 81, known means such as welding, pin fixing, and bolt fixing can be used without particular limitation.

[0097] In the electrolytic cell 300, the peripheral portion of the anode 40 is held by the rigid current collector 91, the current collector 71, the elastic body 81, and / or the flange portion 51b of the anode side frame 51, preferably by the rigid current collector 91. When the peripheral portion of the anode 40 is held by the rigid current collector 91, the current collector 71, the elastic body 81, and / or the flange portion 51b of the anode side frame 51, a known method such as welding, pinning, bolting, or folding into the rigid current collector 91 or the current collector 71 (i.e., hooking the valley formed by bending the peripheral portion of the anode 40 on the peripheral portion of the rigid current collector 91 or the peripheral portion of the current collector 71) can be adopted without particular limitation.

[0098] In the electrolytic cell 300, the peripheral edge of the cathode 20 is held by the current collector 72, the elastic body 82, and / or the flange 52b of the cathode side frame 52. When holding the peripheral edge of the cathode 20 to the current collector 72, the elastic body 82, and / or the flange 52b of the cathode side frame 52, any known method such as welding, pinning, bolting, or folding into the current collector 72 (i.e., hooking the valley formed by bending the peripheral edge of the cathode 20 to the peripheral edge of the current collector 72) can be employed without particular limitation.

[0099] In the electrolytic cell 300, the diaphragm 10, the anode 40, the rigid current collector 91 and the first elastomer 81 are arranged in this order (i.e., the anode 40 is arranged between the diaphragm 10 and the first elastomer 81 and the rigid current collector 91 is arranged between the anode 40 and the first elastomer 81), the anode 40 is pressed toward the cathode 20 (i.e., toward the diaphragm 10) by the first elastomer 81 through the rigid current collector 91, and the diaphragm 10, the cathode 20 and the second elastomer 82 are arranged in this order (i.e., the cathode 20 is arranged between the diaphragm 10 and the second elastomer 82), and the cathode 20 is pressed toward the anode 40 (i.e., toward the diaphragm 10) by the second elastomer 82, thereby realizing a zero gap structure. In the electrolytic cell 300, the process of replacing an anode 40 that has reached the end of its life with a new anode 40 includes: (1) separating the anode side frame 51 from the gasket 30; (2) separating the diaphragm 10 from the anode 40; (3) removing the anode 40 from the anode chamber A; and (4) assembling the electrolytic cell 300 using the new anode 40 in place of the removed anode 40. In the electrolytic cell 300, the removal of the anode 40 in (3) and the assembly of the new anode 40 in (4) are easy. In particular, when the peripheral edge of the anode 40 is retained by the rigid current collector 91, the removal of the anode 40 can be accomplished by simply disconnecting the anode 40 from the rigid current collector 91, and the assembly of the anode 40 can be accomplished by simply fixing the anode 40 to the rigid current collector 91. Furthermore, in the assembled electrolytic cell 300, the positions of the anode 40 and the cathode 20 are automatically adjusted by the first elastic body 81 and the second elastic body 82. Therefore, when assembling a new anode 40, there is no need for complicated operations (such as aligning the height of the ends of the conductive ribs 913 by grinding, etc., as in the conventional zero-gap type alkaline water electrolytic cell) Figure 1 ). ). Therefore, the anode 40 can also be easily replaced in the electrolytic cell 300. Furthermore, the electrolytic cell 300 includes a rigid current collector 91 between the anode 40 and the first elastic body 81. This allows the pressure exerted by the anode 40 and cathode 20 against the diaphragm 10 to be more uniform across the entire surface of both electrodes, thereby making the current density more uniform. Furthermore, the electrolytic cell 300 includes a rigid current collector 91 between the anode 40 and the first elastic body 81. This reduces deformation and wear of the diaphragm 10 caused by pressure fluctuations within the electrode chamber.

[0100] In the above description of the present invention, an alkaline water electrolysis cell 300 is used as an example in which the conductive elastic body 81 presses the anode 40 toward the cathode 20 via the rigid current collector 91. However, the present invention is not limited to this embodiment. For example, an alkaline water electrolysis cell may also be used in which the conductive elastic body presses the cathode toward the anode via the rigid current collector. Figure 5 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 400 (hereinafter sometimes referred to as “electrolysis cell 400”) according to another embodiment. Figure 5 Sometimes, Figures 2 to 4 The element annotation represented in Figures 2 to 4 The same reference numerals as in the figure are used and their descriptions are omitted. Figure 5 As shown, the electrolytic cell 400 includes: a conductive anode-side frame 51 defining an anode chamber A; a conductive cathode-side frame 52 defining a cathode chamber C; an ion-permeable diaphragm 10 disposed between the anode-side frame 51 and the cathode-side frame 52, dividing the anode chamber A from the cathode chamber C; gaskets 30, 30, sandwiched between the anode-side frame 51 and the cathode-side frame 52, retaining the periphery of the diaphragm 10; an anode 40 disposed within the anode chamber A without being retained by the gasket 30; and a cathode 20 disposed within the cathode chamber C without being retained by the gasket 30. In the electrolytic cell 400, the anode 40 is a flexible first porous plate. In the electrolytic cell 400, the cathode 20 can be a rigid porous plate or a flexible porous plate (a second porous plate), but is preferably a flexible porous plate. The electrolytic cell 400 includes: at least one conductive rib (first conductive rib) 61 protruding from the inner wall of the anode-side frame 51; a current collector (first current collector) 71 held by the conductive rib 61; and an elastic body (first elastic body) 81 held by the current collector 71 and having conductivity, with the anode 40 being pressed toward the cathode 20 by the elastic body 81. The electrolytic cell 400 further includes: at least one conductive rib (second conductive rib) 62 protruding from the inner wall of the cathode-side frame 52; a current collector (second current collector) 72 held by the conductive rib 62; an elastic body (second elastic body) 82 held by the current collector 72 and having conductivity; and a rigid current collector 91 disposed between the elastic body 82 and the cathode 20 and having conductivity, with the cathode 20 being pressed toward the anode 40 by the elastic body 82 via the rigid current collector 91. That is, in the electrolytic cell 400 , the rigid current collector 91 is arranged so that the cathode 20 is sandwiched between the rigid current collector 91 and the separator 10 , and the cathode 20 is supported by the rigid current collector 91 .

[0101] In the electrolytic cell 400, the peripheral edge of the anode 40 is held by the current collector 71, the elastic body 81, and / or the flange 51b of the anode side frame 51. When holding the peripheral edge of the anode 40 to the current collector 71, the elastic body 81, and / or the flange 51b of the anode side frame 51, any known method such as welding, pinning, bolting, or folding into the current collector 71 (i.e., hooking the valley formed by bending the peripheral edge of the anode 40 onto the peripheral edge of the current collector 71) can be employed without particular limitation.

[0102] In the electrolytic cell 400, the peripheral portion of the cathode 20 is held by the rigid current collector 91, the current collector 72, the elastic body 82 and / or the flange portion 52b of the cathode side frame 52, preferably held by the rigid current collector 91. When the peripheral portion of the cathode 20 is held by the rigid current collector 91, the current collector 72, the elastic body 82 and / or the flange portion 52b of the cathode side frame 52, a known method such as welding, pinning, bolting, or folding into the rigid current collector 91 or the current collector 72 (i.e., hanging the valley formed by bending the peripheral portion of the cathode 20 on the peripheral portion of the rigid current collector 91 or the peripheral portion of the current collector 72) can be adopted without particular limitation.

[0103] In the electrolytic cell 400, the diaphragm 10, the anode 40 and the first elastomer 81 are arranged in this order (i.e., the anode 40 is arranged between the diaphragm 10 and the first elastomer 81), and the anode 40 is pressed toward the cathode 20 (i.e., toward the diaphragm 10) by the first elastomer 81, and the diaphragm 10, the cathode 20, the rigid current collector 91 and the second elastomer 82 are arranged in this order (i.e., the cathode 20 is arranged between the diaphragm 10 and the second elastomer 82 and the rigid current collector 91 is arranged between the cathode 20 and the second elastomer 82), and the cathode 20 is pressed toward the anode 40 (i.e., toward the diaphragm 10) by the second elastomer 82 via the rigid current collector 91, thereby realizing a zero gap structure. In the electrolytic cell 400, the operation of replacing the anode 40 whose life has expired with a new anode 40 includes: (1) separating the anode side frame 51 from the gasket 30; (2) separating the diaphragm 10 from the anode 40; (3) removing the anode 40 from the anode chamber A; and (4) assembling the electrolytic cell 400 using a new anode 40 instead of the removed anode 40. In the electrolytic cell 400, the removal of the anode 40 in (3) and the assembly of the new anode 40 in (4) are easy. In addition, in the assembled electrolytic cell 400, the positions of the anode 40 and the cathode 20 are automatically adjusted by the first elastic body 81 and the second elastic body 82. Therefore, when assembling the new anode 40, there is no need for complicated operations (such as the operation of aligning the height of the end of the conductive rib 913 by grinding, etc. (see FIG. 1 )) as in the conventional zero-gap type alkaline water electrolytic cell. Figure 1 ). ). Therefore, the anode 40 can also be easily replaced in the electrolytic cell 400. Furthermore, the electrolytic cell 400 includes a rigid current collector 91 between the cathode 20 and the second elastic body 82. This allows the pressure exerted by the anode 40 and cathode 20 against the diaphragm 10 to be more uniform across the entire surface of both electrodes, thereby making the current density more uniform. Furthermore, the electrolytic cell 400 includes a rigid current collector 91 between the cathode 20 and the second elastic body 82. This reduces deformation and wear of the diaphragm 10 caused by pressure fluctuations within the electrode chamber.

[0104] In the above description of the present invention, the alkaline water electrolysis cells 100 to 400 are exemplified as having conductive ribs 61 in the anode chamber and conductive ribs 62 in the cathode chamber. However, the present invention is not limited to this embodiment. For example, the alkaline water electrolysis cell may have conductive ribs in only one of the anode chamber and the cathode chamber, or may have no conductive ribs in either the anode chamber or the cathode chamber. Figure 6 1 is a cross-sectional view schematically illustrating an alkaline water electrolysis cell 500 (hereinafter sometimes referred to as “electrolysis cell 500”) according to another embodiment. Figure 6 Sometimes, Figures 2 to 5 The element annotation represented in Figures 2 to 5 The same reference numerals as in the figure are used and their descriptions are omitted. Figure 6 As shown, the electrolytic cell 500 includes: a conductive anode-side frame 51 defining an anode chamber A; a conductive cathode-side frame 52 defining a cathode chamber C; an ion-permeable diaphragm 10 disposed between the anode-side frame 51 and the cathode-side frame 52, dividing the anode chamber A from the cathode chamber C; gaskets 30, 30, sandwiched between the anode-side frame 51 and the cathode-side frame 52, retaining the periphery of the diaphragm 10; an anode 40 disposed within the anode chamber A without being retained by the gasket 30; and a cathode 20 disposed within the cathode chamber C without being retained by the gasket 30. In the electrolytic cell 500, the anode 40 is a flexible first porous plate. The cathode 20 may be a flexible second porous plate or a rigid porous plate, preferably a rigid porous plate. The electrolytic cell 500 includes a conductive elastic body (first elastic body) 81 disposed between the conductive partition wall 51a of the anode side frame 51 and the anode 40, so as to be in direct contact with the partition wall 51a and the anode 40. The anode 40 is pressed toward the cathode 20 by the elastic body 81. The electrolytic cell 500 also includes a conductive elastic body (second elastic body) 82 disposed between the conductive partition wall 52a of the cathode side frame 52 and the cathode 20, so as to be in direct contact with the partition wall 52a and the cathode 20. The cathode 20 is pressed toward the anode 40 by the elastic body 82.

[0105] In electrolytic cell 500, the periphery of anode 40 is held by elastic body 81 and / or anode side frame 51. When holding the periphery of anode 40 by elastic body 81 and / or anode side frame 51, known methods such as welding, pinning, and bolting can be employed without particular limitation.

[0106] In the electrolytic cell 500, the periphery of the cathode 20 is held by the elastic body 82 and / or the cathode side frame 52. The periphery of the cathode 20 is held by the elastic body 82 and / or the cathode side frame 52 by any known method such as welding, pinning, or bolting without particular limitation.

[0107] In the electrolytic cell 500, the anode 40 is disposed between the diaphragm 10 and the first elastic body 81 and is pressed toward the cathode 20 by the first elastic body 81. Furthermore, the cathode 20 is disposed between the diaphragm 10 and the second elastic body 82 and is pressed toward the anode 40 by the second elastic body 82, thereby achieving a zero-gap structure. In the electrolytic cell 500, the process of replacing an anode 40 that has reached the end of its life with a new anode 40 includes: (1) separating the anode side frame 51 from the gasket 30; (2) separating the diaphragm 10 from the anode 40; (3) removing the anode 40 from the anode chamber A; and (4) assembling the electrolytic cell 500 using the new anode 40 in place of the removed anode 40. In the electrolytic cell 500, the removal of the anode 40 in (3) and the assembly of the new anode 40 in (4) are easy. Furthermore, in the assembled electrolytic cell 500, the positions of the anode 40 and the cathode 20 are automatically adjusted by the first elastic body 81 and the second elastic body 82. Therefore, when assembling a new anode 40, there is no need for complicated operations (such as aligning the height of the ends of the conductive ribs 913 by grinding, etc., as in the conventional zero-gap type alkaline water electrolytic cell) Figure 1 ). ). Therefore, the anode 40 can be easily replaced in the electrolytic cell 500. Furthermore, in the electrolytic cell 500, the anode chamber A and the cathode chamber C do not have conductive ribs, thereby reducing the thickness of each electrolytic unit. This allows the electrolytic cell to be miniaturized and increase the gas production per unit area. Furthermore, the lack of conductive ribs in one or both of the anode chamber and the cathode chamber reduces the materials used to construct the electrolytic cell and the number of steps required to manufacture the cell.

[0108] Description of Reference Numerals

[0109] 10. (ion-permeable) diaphragm; 20, 21. cathode; 30. gasket; 40. anode; 51. anode side frame; 52. cathode side frame; 51a, 52a. (conductive) partition wall; 51b, 52b. flange; 61, 62. conductive rib; 71, 72. current collector; 81, 82. conductive elastic body; 91. rigid current collector; 900. conventional zero-gap alkaline water Electrolytic cell; 910, electrode chamber unit; 911, conductive partition wall; 912, flange portion; 913, 914, conductive ribs; 920, ion-permeable diaphragm; 930, gasket; 940, anode; 950, current collector; 960, conductive elastomer; 970, cathode; 100, 200, 300, 400, 500, 900, alkaline water electrolyzer; A, anode chamber; C, cathode chamber.

Claims

1. An alkaline water electrolyzer, wherein: The alkaline water electrolyzer comprises: an anode side frame defining an anode chamber; a cathode side frame defining a cathode chamber; an ion-permeable diaphragm disposed between the anode-side frame and the cathode-side frame to divide the anode chamber and the cathode chamber; a gasket sandwiched between the anode-side frame and the cathode-side frame, the gasket holding the peripheral edge of the diaphragm; an anode disposed inside the anode chamber without being held by the gasket; a cathode disposed inside the cathode chamber without being held by the gasket; as well as a first elastic body, which is disposed inside the anode chamber and has electrical conductivity, The anode is a flexible first porous plate, The anode is disposed between the separator and the first elastic body, and the anode is pressed toward the cathode by the first elastic body. The alkaline water electrolyzer further includes a first rigid current collector, which is arranged in contact with the anode and has conductivity. The first rigid current collector is arranged between the anode and the first elastic body, and the anode is supported by the first rigid current collector. The alkaline water electrolyzer further includes a second elastic body, which is disposed inside the cathode chamber and has conductivity. The cathode is a flexible second porous plate, disposed between the diaphragm and the second elastic body, and is pressed toward the anode by the second elastic body. The alkaline water electrolyzer is operated so that the pressure on the cathode chamber side where hydrogen is generated is higher than the pressure on the anode chamber side where oxygen is generated.

2. The alkaline water electrolyzer according to claim 1, wherein The anode chamber comprises: at least one first conductive rib protruding from the inner wall of the anode-side frame; and a conductive first current collector held by the first conductive rib, The first elastic body is supported by the first current collector.

3. The alkaline water electrolyzer according to claim 1 or 2, wherein: The cathode chamber comprises: at least one second conductive rib protruding from the inner wall of the cathode side frame; and a conductive second current collector held by the second conductive rib, The second elastic body is supported by the second current collector.

4. The alkaline water electrolyzer according to claim 1 or 2, wherein: The alkaline water electrolyzer further comprises a second rigid current collector, which is arranged in contact with the cathode and has conductivity. The second rigid current collector is arranged between the cathode and the second elastic body. The cathode is supported by the second rigid current collector.

5. A method for replacing an electrode of an alkaline water electrolyzer, which is a method for replacing the anode in the alkaline water electrolyzer according to any one of claims 1 to 4, wherein: The electrode replacement method of the alkaline water electrolyzer comprises: separating the anode side frame from the gasket; separating the separator from the anode; removing the anode from the anode chamber; and The alkaline water electrolyzer was assembled using a new anode in place of the anode.

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