Electrolysis cell and electrolysis device

Abstract

In an electrolysis cell according to the present disclosure, an insulating packing material has: an annular packing body; an arc-shaped packing material having an arc shape formed inside the packing body and surrounding a first supply hole and a first discharge hole from the outer peripheral side, respectively; and a triangular packing material. In the arc-shaped packing material, which is in a state prior to elastic deformation by being sandwiched between a separator and an anion exchange membrane, the thickness of the arc-shaped packing material is set to be greater than the gap between a first diffusion guide part and the anion exchange membrane, and in the triangular packing material, the thickness thereof is set to be greater than that of the packing body.

Description

DESCRIPTIONTITLE OF INVENTION: ELECTROLYSIS CELL AND ELECTROLYZER TECHNICAL FIELD

[0001] The present disclosure relates to an electrolysis cell and an electrolyzer.Priority is claimed on Japanese Patent Application No. 2024-053567, filed March 28, 2024, the content of which is incorporated herein by reference.BACKGROUND ART

[0002] As a device for generating hydrogen, a device that electrolyzes water (an electrolyzer) is known. In this type of device, an electrolysis tank partitioned into a cathode chamber and an anode chamber by an ion exchange membrane is filled with water, and electrolysis of water is performed by supplying electric power to a cathode and an anode. In the cathode chamber, hydrogen is generated by a reaction between water and electrons. Hydroxide ions generated by the reaction pass through the ion exchange membrane and reach the anode chamber. In the anode chamber, oxygen and water are generated from the hydroxide ions. By continuing such reactions, a large amount of hydrogen can be obtained.

[0003] More specifically, the ion exchange membrane is sandwiched from both sides in a thickness direction by plate-shaped members called separators, and flow paths through which an electrolyte flows are formed on surfaces of the separators. In order to prevent leakage of the electrolyte from the flow paths, a sealing member (insulating packing) is interposed between the separators and the ion exchange membrane (see, for example, Patent Document 1). In a device according to Patent Document 1, a resin material having a uniform thickness is used as the sealing member.Citation ListPatent Document

[0004] Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2021-191886SUMMARY OF INVENTIONTechnical Problem

[0005] Here, when the electrolyte flows through the flow path under high pressure, a contact pressure distribution between the separator and the insulating packing tends to vary depending on position. Accordingly, when an insulating packing having a uniform thickness is used as described above, a sufficient sealing effect cannot be obtained in a region where the contact pressure is low. As a result, leakage of the electrolyte may occur.

[0006] The present disclosure has been made to solve the above-described problem, and an object of the present disclosure is to provide an electrolysis cell and an electrolyzer, in which leakage of an electrolyte is further suppressed.Solution to Problem

[0007] In order to solve the above-described problem, an electrolysis cell according to the present disclosure includes: a pair of separators, an anion exchange membrane disposed between the pair of separators, and an insulating packing provided between the anion exchange membrane and each of the separators. Each of the separators includes: a separator main body having a rectangular plate shape and having a first surface facing one side in a thickness direction and a second surface facing the other side in the thickness direction; a first supply hole and a first discharge hole that are formed on one diagonal line of the separator main body on the first surface and penetrate the separator main body from the first surface toward the second surface; a main flow path having a plurality of first groove portions that are formed in a region between the first supply hole and the first discharge hole, extend in a longitudinal direction of the separator main body, and are arranged at intervals from each other in a width direction orthogonal to the longitudinal direction; a first diffusion flow path that extends from the first supply hole to the first groove portions, is recessed from the first surface side toward the second surface side, and has a trapezoidal shape in which a dimension in the width direction gradually increases from the first supply hole toward the first groove portions as viewed from the first surface side; a first convergence flow path that extends from the first groove portions to the first discharge hole, is recessed from the first surface side toward the second surface side, and has a trapezoidal shape in which a dimension in the width direction gradually decreases from the first groove portions toward the first discharge hole as viewed from the first surface side; a first diffusion guide portion that is provided in the first diffusion flow path, protrudes from the second surface side toward the first surface side, and extends radially from the first supply hole to guide a fluid from the first supply hole to the first groove portions; and a first convergence guide portion that is provided in the first convergence flow path, protrudes from the second surface side toward the first surface side, and extends radially from the first discharge hole to guide the fluid from the first groove portions to the first discharge hole. The insulating packing includes: a packing main body that is disposed outside the main flow path, the first diffusion flow path, and the first convergence flow path, and has an annular shape as viewed from the first surface side; an arc packing that is formed inside the packing main body, extends so as to bridge the first diffusion guide portion and the first convergence guide portion, and has an arc shape surrounding each of the first supply hole and the first discharge hole from an outer peripheral side; and a triangular packing that is formed inside the packing main body and extends to oblique sides of the first diffusion flow path and the first convergence flow path. In the arc packing in a state before the arc packing is sandwiched between one of the separators and the anion exchange membrane and elastically deformed, a thickness of the arc packing is set to be greater than a gap between the first diffusion guide portion and the anion exchange membrane.

[0008] An electrolyzer according to the present disclosure includes the above-described electrolysis cell, an electrolyte supply unit that supplies an electrolyte to the electrolysis cell, and a power supply section that applies a voltage to the electrolysis cell.Advantageous Effects of Invention

[0009] According to the present disclosure, it is possible to provide an electrolysis cell and an electrolyzer in which leakage of an electrolyte is further suppressed.BRIEF DESCRIPTION OF DRAWINGS

[0010] [FIG. 1] A schematic view illustrating a configuration of an electrolyzer according to an embodiment of the present disclosure.[FIG. 2] A schematic cross-sectional view representing a configuration of an electrolysis cell according to an embodiment of the present disclosure.[FIG. 3] An exploded perspective view representing the configuration of the electrolysis cell according to the embodiment of the present disclosure.[FIG. 4] A plan view representing a configuration of a separator and an insulating packing according to the embodiment of the present disclosure.[FIG. 5] A schematic cross-sectional view representing a configuration of an electrolysis cell stack according to an embodiment of the present disclosure.[FIG. 6] A cross-sectional view taken along a line VI-VI in FIG. 4.[FIG. 7] A cross-sectional view taken along a line VII-VII in FIG. 4.[FIG. 8] A graph representing a relationship between a material for the insulating packing according to the embodiment of the present disclosure and an example of results of a load test.[FIG. 9] A cross-sectional view representing a modification example of the separator according to the embodiment of the present disclosure.[FIG. 10] A plan view representing a further modification example of the separator according to the embodiment of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0011] Hereinafter, an electrolysis cell and an electrolyzer according to embodiments of the present disclosure will be described with reference to FIGS. 1 to 7.

[0012] An embodiment for implementing an electrolyzer 1 according to the present disclosure will be described with reference to the accompanying drawings. In the following description, components having the same or similar functions are denoted by the same reference numerals. In the present specification, "facing" means that two members overlap when viewed in a certain direction, and may include a case where another member (for example, another layer) exists between the two members.

[0013] First, with reference to FIG. 2, a Z direction, an X direction, and a Y direction are defined. The Z direction is a direction from a first separator 11a described later toward a second separator 11b described later (the right side in FIG. 2). The X direction is a direction intersecting (for example, orthogonal to) the Z direction, and is a direction from a central portion C of an electrolysis cell 12 to one end portion of the electrolysis cell 12 (an up-down direction in FIG. 2). The X direction is, for example, a vertical direction. The Y direction is a direction intersecting (for example, orthogonal to) the Z direction and the X direction, and is, for example, a depth direction of the drawing sheet in FIG. 2. In the present specification, "outer size" means an outer size when viewed in the Z direction.

[0014] FIG. 1 is a schematic configuration view showing an overall configuration of an electrolyzer 1 according to a first embodiment. The electrolyzer 1 is, for example, a device that generates hydrogen by electrolyzing water contained in an electrolyte. The electrolyzer 1 is, for example, an anion exchange membrane (AEM)-type electrolyzer. However, the electrolyzer 1 is not limited to the above-described example, and may be a different type of electrolyzer such as a proton exchange membrane (Polymer Electrolyte Membrane; PEM)-type electrolyzer or a device that electrolytically reduces carbon dioxide.

[0015] The electrolyzer 1 includes, for example, an electrolysis cell stack 10, an electrolyte supply unit 20, and a power supply section 30.

[0016] (Electrolysis cell stack)The electrolysis cell stack 10 electrolyzes an electrolyte Es supplied from the outside. The electrolysis cell stack 10 is an assembly of a plurality of separators 11 and a plurality of electrolysis cells 12. The electrolysis cell stack 10 is formed by arranging the plurality of separators 11 and the plurality of electrolysis cells 12 in one direction. In the present embodiment, a case where five separators 11 and four electrolysis cells 12 are arranged to form the electrolysis cell stack 10 will be described as an example (see FIG. 6).

[0017] Hereinafter, the above-described one direction (the left-right direction in FIG. 6) in which the plurality of separators 11 and the plurality of electrolysis cells 12 are arranged is referred to as "first direction D1". In addition, one side in the first direction D1 (the left side in FIG. 6) is simply referred to as "one side dl", and a side opposite to the one side dl is referred to as "other side dr". Hereinafter, for convenience of explanation, the five separators 11 may be referred to in order from the one side dl as "first separator 11a", "second separator 11b", "third separator 11c", "fourth separator 11d", and "fifth separator 11e". In addition, the four electrolysis cells 12 may be referred to in order from the one side dl as "first electrolysis cell 12a", "second electrolysis cell 12b", "third electrolysis cell 12c", and "fourth electrolysis cell 12d".

[0018] As shown in FIG. 5, the electrolysis cell stack 10 includes a plurality of (four) electrolysis cells 12 that each form a cathode chamber Sa and an anode chamber Sb together with the separators 11, first flow path portions 13 and 13' (described later) through which the electrolyte Es supplied from the electrolyte supply unit 20 flows toward the cathode chambers Sa and the anode chambers Sb, and second flow path portions 14 and 14' (described later) through which the electrolyte after reaction in the cathode chambers Sa and the anode chambers Sb flows (returns) toward the electrolyte supply unit 20. The electrolysis cell stack 10 will be described later in detail. The number of separators 11 and the number of electrolysis cells 12 are not limited to the above numbers. Each of the electrolysis cells 12 includes a cathode chamber Sa and an anode chamber Sb. The electrolysis cell 12 will also be described later in detail.

[0019] (Electrolyte supply unit)The electrolyte supply unit 20 is a supply unit that supplies the electrolyte Es to each of the electrolysis cells 12. The electrolyte Es is, for example, pure water or an alkaline aqueous solution. The electrolyte supply unit 20 includes a cathode-side supply unit 20a and an anode-side supply unit 20b.

[0020] The cathode-side supply unit 20a is a supply unit that supplies the electrolyte Es to the cathode chamber Sa of each of the electrolysis cells 12. The cathode-side supply unit 20a includes, for example, a hydrogen gas-liquid separation device 21, a first pump 22, a hydrogen recovery unit 23, a first electrolyte supply unit 24, and piping lines L1 and L2.

[0021] The hydrogen gas-liquid separation device 21 stores the electrolyte Es. A supply port of the hydrogen gas-liquid separation device 21 is connected to the cathode chamber Sa of the electrolysis cell 12 through the piping line L1. The first pump 22 is provided midway along the piping line L1, and sends the electrolyte Es stored in the hydrogen gas-liquid separation device 21 toward the cathode chamber Sa of the electrolysis cell 12.

[0022] A return port of the hydrogen gas-liquid separation device 21 is connected to the cathode chamber Sa of the electrolysis cell 12 through the piping line L2. The electrolyte Es containing hydrogen generated by the electrolysis cell 12 flows into the hydrogen gas-liquid separation device 21 from the electrolysis cell 12. The hydrogen gas-liquid separation device 21 has a gas-liquid separation section that separates hydrogen contained in the electrolyte Es. The hydrogen separated from the electrolyte Es by the hydrogen gas-liquid separation device 21 is recovered by the hydrogen recovery unit 23. The hydrogen gas-liquid separation device 21 is replenished with the electrolyte Es from the first electrolyte supply unit 24.

[0023] On the other hand, the anode-side supply unit 20b is a supply unit that supplies the electrolyte Es to the anode chamber Sb of each of the electrolysis cells 12. The anode-side supply unit 20b includes, for example, an oxygen gas-liquid separation device 26, a second pump 27, an oxygen recovery unit 28, a second electrolyte supply unit 29, and piping lines L3 and L4.

[0024] The oxygen gas-liquid separation device 26 stores the electrolyte Es. A supply port of the oxygen gas-liquid separation device 26 is connected to the anode chamber Sb of the electrolysis cell 12 through the piping line L3. The second pump 27 is provided midway along the piping line L3, and sends the electrolyte Es stored in the oxygen gas-liquid separation device 26 toward the anode chamber Sb of the electrolysis cell 12.

[0025] A return port of the oxygen gas-liquid separation device 26 is connected to the anode chamber Sb of the electrolysis cell 12 through the piping line L4. The electrolyte Es containing oxygen generated by the electrolysis cell 12 flows into the oxygen gas-liquid separation device 26 from the electrolysis cell 12. The oxygen gas-liquid separation device 26 has a gas-liquid separation section that separates oxygen contained in the electrolyte Es. The oxygen separated from the electrolyte Es by the oxygen gas-liquid separation device 26 is recovered by the oxygen recovery unit 28. The oxygen gas-liquid separation device 26 is replenished with the electrolyte Es from the second electrolyte supply unit 29.

[0026] (Power supply section)The power supply section 30 is a DC power supply device that applies a voltage to each of the separators 11 in the electrolysis cell stack 10. By applying a voltage to each separator 11 in the first direction D1, the power supply section 30 applies a DC voltage necessary for electrolysis of the electrolyte Es between an anode 122 and a cathode 121 of each electrolysis cell 12.

[0027] (Configuration of electrolysis cell stack)Next, the electrolysis cell stack 10 will be described in detail with reference to FIGS. 2 to 6. FIG. 2 is a view schematically showing a part of the electrolysis cell stack 10. FIG. 2 shows, among the electrolysis cells 12 arranged in the first direction D1 (the left-right direction in FIG. 5), the electrolysis cell 12 disposed closest to the one side dl (the first electrolysis cell 12a).

[0028] As shown in FIG. 5, the electrolysis cell stack 10 includes, for example, a plurality of separators 11 and a plurality of electrolysis cells 12.

[0029] (Separator)The separator 11 is a member that defines an internal space S where the electrolysis cell 12 is disposed. The internal space S is a space including the cathode chamber Sa and the anode chamber Sb, which will be described later. For example, the separator 11 has a rectangular plate shape as viewed in the first direction D1, and is formed of a metal member or the like. The separators 11 are arranged at intervals from each other in the first direction D1.

[0030] The separator 11 has a first surface 201a facing one side in the thickness direction and a second surface 201b facing the other side in the thickness direction. Configurations of the first surface 201a and the second surface 201b (described later) are point-symmetric with respect to a geometric centroid of the separator 11. Hereinafter, a configuration on the first surface 201a side will be described as a representative example with reference to FIG. 4.

[0031] The separator 11 includes a rectangular plate-shaped separator main body 201, a first discharge hole 202, a first supply hole 203, a first groove portion 204 (main flow path 204a), a first convergence flow path 205, a first diffusion flow path 206, a first convergence guide portion 207, a first diffusion guide portion 208, a straight section 209, a second discharge hole 210, a second supply hole 211, and a second groove portion 212.

[0032] The first supply hole 203 and the first discharge hole 202 are respectively disposed at corner portions along one of two diagonal lines connecting corner portions of the rectangular separator main body 201. The first supply hole 203 and the first discharge hole 202 are circular holes penetrating the separator main body 201 from the first surface side toward the second surface side. A diameter of the first discharge hole 202 is set to be larger than a diameter of the first supply hole 203. In addition, the second supply hole 211 and the second discharge hole 210 are provided at respective corner portions along the other of the two diagonal lines connecting the corner portions of the separator main body 201.

[0033] The first groove portion 204, the first diffusion flow path 206, the first convergence flow path 205, the first diffusion guide portion 208, and the first convergence guide portion 207 are formed only on the first surface 201a. The first groove portion 204 is formed in a region between the first supply hole 203 and the first discharge hole 202. A plurality of first groove portions 204 extend in a longitudinal direction of the separator main body 201 and are arranged at intervals from each other in a width direction orthogonal to the longitudinal direction. The first groove portion 204 has a rectangular cross-sectional shape recessed from the first surface 201a side toward the second surface 201b side.

[0034] The first diffusion flow path 206 extends from the first supply hole 203 to the first groove portions 204 and is recessed from the first surface 201a side toward the second surface 201b side, thereby forming a flow path. The first diffusion flow path 206 has a trapezoidal shape in which a dimension in the width direction gradually increases from the first supply hole 203 toward the first groove portions 204, as viewed from the first surface 201a side. More specifically, the first diffusion flow path 206 is defined by a first side portion 206a extending in the width direction from an edge of the first supply hole 203, a second side portion 206b extending in a direction orthogonal to the first side portion 206a (the above-described longitudinal direction), and an oblique side 206c facing the second side portion 206b in the width direction. The oblique side 206c extends in a direction away from the first supply hole 203 from one side toward the other side in the longitudinal direction. An angle formed by the oblique side 206c with respect to the width direction is preferably 24° or more and 50° or less. More preferably, the angle is 30° or more and 45° or less. Most preferably, the angle is 35° or more and 40° or less.

[0035] The first diffusion guide portion 208 is provided in the first diffusion flow path 206. A plurality of first diffusion guide portions 208 protrude from the first surface 201a and are provided radially around the first supply hole 203. The farther the first diffusion guide portion 208 is from the first supply hole 203, the smaller an angle formed with respect to the width direction becomes. In addition, the farther the first diffusion guide portion 208 is from the first supply hole 203, the larger a dimension thereof in the longitudinal direction becomes.

[0036] The straight section 209 is provided between the first convergence flow path 205 and the first groove portion 204. In the straight section 209, a dimension in the width direction is constant over the entire region in the longitudinal direction. In addition, the dimension of the straight section 209 in the longitudinal direction is preferably approximately 25 mm.

[0037] The first convergence flow path 205 extends from the first groove portion 204 to the first discharge hole 202 and is recessed from the first surface 201a side toward the second surface 201b side, thereby forming a flow path. The first convergence flow path 205 has a trapezoidal shape in which a dimension in the width direction gradually increases from the first discharge hole 202 toward the first groove portion 204, as viewed from the first surface 201a side.

[0038] The first convergence guide portion 207 is provided in the first convergence flow path 205. A plurality of first convergence guide portions 207 protrude from the first surface 201a and are provided radially around the first discharge hole 202. The farther the first convergence guide portion 207 is from the first discharge hole 202, the smaller an angle formed with respect to the width direction becomes. In addition, the farther the first convergence guide portion 207 is from the first discharge hole 202, the larger a dimension thereof in the longitudinal direction becomes.

[0039] (Electrolysis cell)The electrolysis cell (Membrane Electrode Assembly; MEA) 12 is a structure assembled by laminating an ion exchange membrane, a catalyst, a current collector, and the like. As shown in FIG. 2 or 5, one electrolysis cell 12 is disposed between each pair of adjacent separators 11, and the electrolysis cell 12 connects the adjacent separators 11 to each other in the first direction D1. Therefore, the electrolysis cell 12 is located in the internal space S between the two adjacent separators 11. The electrolysis cell 12 includes, for example, an ion exchange membrane 120, a cathode 121, and an anode 122.

[0040] (Ion exchange membrane)The ion exchange membrane 120 is a membrane that selectively allows permeation of ions. The ion exchange membrane 120 is, for example, a solid polymer electrolyte membrane. The ion exchange membrane 120 is, for example, an anion exchange membrane (AEM) having hydroxide ion conductivity. However, the ion exchange membrane 120 is not limited to the above-described example, and may be a proton exchange membrane (Polymer Electrolyte Membrane; PEM) having proton conductivity, which is a different type from the above-described example.

[0041] The ion exchange membrane 120 is, for example, in a rectangular sheet shape. An outer size of the ion exchange membrane 120 is, for example, smaller than an outer size of the separators 11 adjacent in the first direction D1. The ion exchange membrane 120 is disposed between the two adjacent separators 11 in the first direction D1 and is located in the internal space S. The ion exchange membrane 120 has a first surface 120a facing the first inner surface 110a of the separator 11 located on the one side dl with respect to the ion exchange membrane 120, and a second surface 120b located on a side opposite to the first surface 120a. The first surface 120a of the ion exchange membrane 120 faces the one side dl. The second surface 120b of the ion exchange membrane 120 faces the other side dr. The second surface 120b of the ion exchange membrane 120 faces the second inner surface 110b of the separator 11 located on the other side dr with respect to the ion exchange membrane 120.

[0042] In the internal space S, the cathode chamber Sa or the anode chamber Sb is defined between the first surface 120a of the ion exchange membrane 120 and the first inner surface 110a of the separator 11, and between the second surface 120b of the ion exchange membrane 120 and the second inner surface 110b of the separator 11. Specifically, the cathode chamber Sa is defined between the first surface 120a of the ion exchange membrane 120 of the first electrolysis cell 12a and the first inner surface 110a of the first separator 11a, and between the first surface 120a of the ion exchange membrane 120 of the third electrolysis cell 12c and the first inner surface 110a of the third separator 11c. On the other hand, the anode chamber Sb is defined between the second surface 120b of the ion exchange membrane 120 of the first electrolysis cell 12a and the second inner surface 110b of the second separator 11b, and between the second surface 120b of the ion exchange membrane 120 of the third electrolysis cell 12c and the second inner surface 110b of the fourth separator 11d.

[0043] In addition, the cathode chamber Sa is defined between the first surface 120a of the ion exchange membrane 120 of the second electrolysis cell 12b and the first inner surface 110a of the second separator 11b, and between the first surface 120a of the ion exchange membrane 120 of the fourth electrolysis cell 12d and the first inner surface 110a of the fourth separator 11d. On the other hand, the anode chamber Sb is defined between the second surface 120b of the ion exchange membrane 120 of the second electrolysis cell 12b and the second inner surface 110b of the third separator 11c, and between the second surface 120b of the ion exchange membrane 120 of the fourth electrolysis cell 12d and the second inner surface 110b of the fifth separator 11e.

[0044] In the cathode chamber Sa, when a voltage is applied to the electrolysis cell 12, a chemical reaction shown in the following (Chem. 1) occurs, and hydrogen is generated from the electrolyte Es. Note that "XX is generated" in the present specification may include a case where another substance is simultaneously generated along with the generation of XX. Hydroxide ions generated in the cathode chamber Sa pass through the electrolysis cell 12 and move from the cathode chamber Sa to the anode chamber Sb.2H2O + 2e- → H2 + 2OH- ... (Chem. 1)

[0045] On the other hand, in the anode chamber Sb, when a voltage is applied to the electrolysis cell 12, a chemical reaction shown in the following (Chem. 2) occurs, and oxygen is generated from the electrolyte Es.2OH- → 1 / 2O2 + H2O + 2e- ... (Chem. 2)

[0046] As a result, in the electrolysis cell 12 as a whole, a chemical reaction shown in the following (Chem. 3) occurs.H2O → H2 + 1 / 2O2 ... (Chem. 3)

[0047] The ion exchange membrane 120 may contain, as an example of a membrane having high ion conductivity, a polystyrene-based or tetraphenyl-based composition in a main chain, and an imidazolium group or a quaternary ammonium group in a side chain. Alternatively, the ion exchange membrane 120 may contain a polysulfone-based or bromobutylstyrene-based composition as an example of a membrane having high oxidation resistance.

[0048] (Cathode)The cathode 121 is disposed between the ion exchange membrane 120 and the separator 11, and is sandwiched between the ion exchange membrane 120 and the separator 11. The cathode 121 includes, for example, a cathode catalyst layer 121a and a cathode current collector121b.

[0049] The cathode catalyst layer 121a is a layer that promotes the chemical reaction in the cathode chamber Sa described above. The cathode catalyst layer 121a is, for example, in a rectangular sheet shape. The cathode catalyst layer 121a is disposed in the cathode chamber Sa and is fixed to the ion exchange membrane 120 by, for example, pressure bonding.

[0050] Specifically, the cathode catalyst layer 121a of the first electrolysis cell 12a, the cathode catalyst layer 121a of the second electrolysis cell 12b, the cathode catalyst layer 121a of the third electrolysis cell 12c, and the cathode catalyst layer 121a of the fourth electrolysis cell 12d are fixed to the first surface 120a of the ion exchange membrane 120 by, for example, pressure bonding. The anode catalyst layers 122a of the first electrolysis cell 12a, the second electrolysis cell 12b, the third electrolysis cell 12c, and the fourth electrolysis cell 12d are fixed to the second surface 120b of the ion exchange membrane 120 by, for example, pressure bonding. A negative voltage is applied to each cathode catalyst layer 121a from the power supply section 30 through the separator 11 and the cathode current collector121b.

[0051] As a material for the cathode catalyst layer 121a, any material that promotes the chemical reaction in the cathode chamber Sa described above may be used, and various materials can be used. For example, the cathode catalyst layer 121a contains one or more of nickel, a nickel alloy, cerium oxide, lanthanum oxide, and platinum. Note that, in the present specification, "XX oxide" may contain another material other than XX and oxygen. The cathode catalyst layer 121a may contain another material such as carbon, in addition to the above-described materials. An outer size of the cathode catalyst layer 121a is, for example, smaller than the outer size of the ion exchange membrane 120.

[0052] The cathode current collector 121b is an electrical connection portion that transmits the voltage applied to the separator 11 to the cathode catalyst layer 121a. The cathode current collector 121b is disposed in the cathode chamber Sa. The cathode current collector 121b is located between the separator 11 and the cathode catalyst layer 121a.

[0053] Specifically, the cathode current collector 121b of the first electrolysis cell 12a is joined to each of the first inner surface 110a of the first separator 11a and the cathode catalyst layer 121a; the cathode current collector 121b of the second electrolysis cell 12b is joined to each of the first inner surface 110a of the second separator 11b and the cathode catalyst layer 121a; and the cathode current collector 121b of the third electrolysis cell 12c is joined to each of the first inner surface 110a of the third separator 11c and the cathode catalyst layer 121a. The anode current collector 122b of the second electrolysis cell 12b is joined to each of the second inner surface 110b of the second separator 11b and the anode catalyst layer 122a; and the anode current collector 122b of the fourth electrolysis cell 12d is joined to each of the first inner surface 110a of the fourth separator 11d and the cathode catalyst layer 121a.

[0054] The cathode current collector 121b has a structure through which the electrolyte Es and gas can pass. The cathode current collector 121b is formed of, for example, a metal mesh structure, a sintered body, fibers, or the like. In the present embodiment, an outer size of the cathode current collector 121b is, for example, the same as the outer size of the cathode catalyst layer 121a.

[0055] (Anode)The anode 122 is disposed between the ion exchange membrane 120 and the separator 11, and is sandwiched between the ion exchange membrane 120 and the second separator 11b. The anode 122 includes, for example, an anode catalyst layer 122a and an anode current collector 122b.

[0056] The anode catalyst layer 122a is a layer that promotes the chemical reaction in the anode chamber Sb described above. The anode catalyst layer 122a is, for example, in a rectangular sheet shape. The anode catalyst layer 122a is disposed in the anode chamber Sb and is fixed to the ion exchange membrane 120 by, for example, pressure bonding.

[0057] Specifically, the anode catalyst layer 122a of the first electrolysis cell 12a and the anode catalyst layer 122a of the third electrolysis cell 12c are fixed to the second surface 120b of the ion exchange membrane 120 by, for example, pressure bonding. The anode catalyst layer 122a of the second electrolysis cell 12b and the anode catalyst layer 122a of the fourth electrolysis cell 12d are fixed to the first surface 120a of the ion exchange membrane 120 by, for example, pressure bonding. A positive voltage is applied to each anode catalyst layer 122a from the power supply section 30 through the separator 11 and the anode current collector 122b.

[0058] As a material for the anode catalyst layer 122a, any material that promotes the chemical reaction in the anode chamber Sb described above may be used, and various materials can be used. For example, the anode catalyst layer 122a contains one or more of nickel, a nickel alloy, nickel oxide, copper oxide, iridium oxide, niobium oxide, lead oxide, and bismuth oxide. As described above, "XX oxide" in the present specification may contain another material other than XX and oxygen. For example, "nickel oxide" may contain another material such as iron and cobalt, in addition to nickel and oxygen. In addition, "copper oxide" may contain another material such as cobalt in addition to copper and oxygen. "Iridium oxide" may contain another material such as ruthenium in addition to iridium and oxygen. "Lead oxide" may contain another material such as ruthenium in addition to lead and oxygen. "Bismuth oxide" may contain another material such as ruthenium in addition to bismuth and oxygen.

[0059] The anode current collector 122b is an electrical connection portion that transmits the voltage applied to the separator 11 to the anode catalyst layer 122a. The anode current collector 122b is disposed in the anode chamber Sb. The anode current collector 122b is located between the separator 11 and the anode catalyst layer 122a.

[0060] Specifically, the anode current collector 122b of the first electrolysis cell 12a is joined to the second inner surface 110b of the second separator 11b and to the anode catalyst layer 122a, and the anode current collector 122b of the third electrolysis cell 12c is joined to the second inner surface 110b of the fourth separator 11d and to the anode catalyst layer 122a. The cathode current collector 121b of the second electrolysis cell 12b is joined to the first inner surface 110a of the third separator 11c and to the cathode catalyst layer 121a, and the cathode current collector 121b of the fourth electrolysis cell 12d is joined to the second inner surface 110b of the fifth separator 11e and to the cathode catalyst layer 121a.

[0061] The anode current collector 122b has a structure through which the electrolyte Es and gas can pass. The anode current collector 122b is formed of, for example, a metal mesh structure, a sintered body, fibers, or the like. In the present embodiment, an outer size of the anode current collector 122b is, for example, the same as the outer size of the anode catalyst layer 122a.

[0062] FIG. 3 is an exploded perspective view showing a part of the electrolysis cell stack 10. In addition to the above-described configuration, the electrolysis cell stack 10 includes, for example, a first current collector 61, a second current collector 62, a first insulating member 65, a second insulating member 66, a first end plate 67, and a second end plate 68. In FIG. 3, the first flow path portion 13 and the second flow path portion 14, which will be described later, are omitted.

[0063] (First current collector)The first current collector 61 is an electrical connection portion that transmits the negative voltage applied from the power supply section 30 to the first separator 11a. That is, the first current collector 61 is electrically connected to the first separator 11a (detailed illustration of the connection is omitted). A negative voltage necessary for electrolysis in each electrolysis cell 12 is applied to the first current collector 61 from the power supply section 30. The first current collector 61 is formed of a metal plate member (for example, a copper plate) or the like.

[0064] (Second current collector)The second current collector 62 is an electrical connection portion that transmits the positive voltage applied from the power supply section 30 to the second separator 11b. That is, the second current collector 62 is electrically connected to the second separator 11b. A positive voltage necessary for electrolysis in each electrolysis cell 12 is applied to the second current collector 62 from the power supply section 30. The second current collector 62 is formed of a metal plate member (for example, a copper plate) or the like.

[0065] (First insulating member)The first insulating member 65 is located between the first current collector 61 and the first end plate 67. An outer size of the first insulating member 65 is, for example, the same as the outer size of the first current collector 61 or larger than the outer size of the first current collector 61.

[0066] (Second insulating member)The second insulating member 66 is located between the second current collector 62 and the second end plate 68. An outer size of the second insulating member 66 is the same as the outer size of the second current collector 62 or larger than the outer size of the second current collector 62.

[0067] (First end plate)The first end plate 67 is located on a side opposite to the first current collector 61 with respect to the first insulating member 65. The first end plate 67 is formed of, for example, a metal plate member (for example, a stainless steel plate) or the like. An outer size of the first end plate 67 is, for example, larger than the outer size of the first insulating member 65.

[0068] (Second end plate)The second end plate 68 is located on a side opposite to the second current collector 62 with respect to the second insulating member 66. The second end plate 68 is formed of, for example, a metal plate member (for example, a stainless steel plate) or the like. An outer size of the second end plate 68 is, for example, larger than the outer size of the second insulating member 66.

[0069] Further, as shown in FIG. 3, the electrolysis cell stack 10 includes, for example, a first insulator 63 and a second insulator 64 in addition to the above-described configuration.

[0070] (First insulator)The first insulator 63 provides insulation between an outer peripheral portion of the separator 11 on the one side dl and an outer peripheral portion of the separator 11 on the other side dr among two adjacent separators 11. The first insulator 63 is a sheet member formed in a frame shape slightly larger than the outer sizes of the cathode catalyst layer 121a and the anode catalyst layer 122a, and the outer sizes of the cathode current collector 121b and the anode current collector 122b.

[0071] (Second insulator)The second insulator 64, similarly to the first insulator 47, provides insulation between the outer peripheral portion of the separator 11 on the other side dr and the outer peripheral portion of the separator 11 on the one side dl among two adjacent separators 11. The second insulator 64 is a sheet member formed in a frame shape slightly larger than the outer sizes of the anode catalyst layer 122a and the cathode catalyst layer 121a, and the outer sizes of the anode current collector 122b and the cathode current collector 121b.

[0072] (Packing)The packing 60 (insulating packing) is a member that closes the internal space S between two adjacent separators 11. The packing 60 is disposed between two adjacent separators 11. The packing 60 is located outside (on an outer peripheral side of) an outer edge portion 120e of the ion exchange membrane 120, and seals the internal space S.

[0073] In the present embodiment, the packing 60 includes the first insulator 63 as a first packing 63 and the second insulator as a second packing 64. The first packing 63 and the second packing 64 may be integrally formed. That is, the first packing 63 and the second packing 64 may be a single member. In addition, the packing 60 may be integrally formed with at least one of the first insulator 63 and the second insulator 64 described above.

[0074] (First packing)The first packing 63 is a packing located near the separator 11 on the one side dl among two adjacent separators 11. The first packing 63 is located outside (on the outer peripheral side of) the outer edge portion 120e of the ion exchange membrane 120. The first packing 63 is sandwiched between the first inner surface 110a of the separator 11 located on the one side dl with respect to the ion exchange membrane 120 and the second packing 64, and seals a part of the outer peripheral side of the internal space S. In the present embodiment, the first packing 63 is sandwiched between the first insulator 47 attached to the first inner surface 110a and the second packing 64. The first packing 63 has an annular shape (for example, a frame shape) along the outer edge portion 120e of the ion exchange membrane 120, and is formed in an annular shape slightly larger than the outer edge portion 120e of the ion exchange membrane 120.

[0075] (Second packing)The second packing 64 is a packing located near the separator 11 on the other side dr among the two adjacent separators 11. The second packing 64 is located outside the outer edge portion 120e of the ion exchange membrane 120. The second packing 64 is sandwiched between the second inner surface 110b of the separator 11 located on the other side dr with respect to the ion exchange membrane 120 and the first packing 63, and seals a part of the outer peripheral side of the internal space S. The second packing 64 has an annular shape (for example, a frame shape) along the outer edge portion 120e of the ion exchange membrane 120, and is formed in an annular shape slightly larger than the outer edge portion 120e of the ion exchange membrane 120.

[0076] A detailed planar shape of the packing 60 will be described with reference to FIGS. 4, 6, and 7. As shown in the figures, the packing 60 includes a packing main body 301, an arc packing 302, and a triangular packing 303. The packing main body 301 is disposed outside the main flow path 204a, the first diffusion flow path 206, and the first convergence flow path 205, and has a rectangular annular shape as viewed from the first surface 201a side. As shown in FIG. 6, one packing main body 301 is provided on each of both sides in the thickness direction of the ion exchange membrane 120, and the packing main bodies 301 sandwich the ion exchange membrane 120 between the pair of separators 11. A width of the packing main body 301 is, for example, 30 mm to 60 mm.

[0077] The arc packing 302 is integrally formed inside the packing main body 301. The arc packing 302 extends so as to bridge the first diffusion guide portions 208 and the first convergence guide portions 207, and has an arc shape surrounding each of the first supply hole 203 and the first discharge hole 202 from an outer peripheral side. More specifically, as shown in FIG. 7, the arc packing 302 faces the triangular packing 303 of the other packing 60 across the ion exchange membrane 120 in the thickness direction.

[0078] Further, the arc packing 302 is disposed to cover the first diffusion guide portion 208 or the first convergence guide portion 207 from a tip end side through a plate-shaped member (not shown). A thickness of the arc packing 302 is set to be greater than a gap between the ion exchange membrane 120 and a tip end of the first diffusion guide portion 208 or a tip end of the first convergence guide portion 207 in a state before elastic deformation due to assembly occurs. Specifically, the thickness of the arc packing 302 is set to be greater than the above-described gap by an amount of 0.1 mm or more and 1.0 mm or less. An apparent thickness in a state in which elastic deformation has occurred after assembly is equivalent to a dimension of the gap. In other words, in an assembled state, the arc packing 302 is compressed from both sides in the thickness direction and elastically deformed, thereby generating a high contact pressure between the separator 11 and the ion exchange membrane 120.

[0079] In addition, as shown in FIG. 7, a thickness of the triangular packing 303 is also set to be greater than a thickness of the packing main body 301 in a state before the elastic deformation. An apparent thickness in a state in which elastic deformation has occurred after assembly is equivalent to the thickness of the packing main body 301. In other words, in an assembled state, the triangular packing 303 is compressed from both sides in the thickness direction and elastically deformed, thereby generating a high contact pressure between the separator 11 and the ion exchange membrane 120.

[0080] Criteria for selecting a material for the packing 60 will be described below. The packing 60 is preferably formed of a material capable of maintaining an elastic compression displacement amount at 90% or more 5 seconds after the load is released from 500 N after 3000 cycles have been applied in a repeated load application test with a total load of 500 N or more, when the elastic compression displacement amount with a contact pressure at a load of 500 N is defined as 100%. In addition, the packing 60 is preferably formed of a material for which, in a repeated load application test with a total load of 500 N or more, when an elastic compression displacement amount at a maximum load of 500 N is defined as 100%, an elastic compression displacement amount 1 second after the load is released is 99% or less of the elastic compression displacement amount at a load of 500 N (see FIG. 8). Examples of a material having such characteristics include ethylene propylene diene rubber having a hardness of 50 or more and 60 or less.

[0081] (Operations and Effects)As described above, the ion exchange membrane 120 is sandwiched from both sides in the thickness direction by the separators 11, and the flow paths through which the electrolyte flows are formed on the surfaces of the separators 11. In order to prevent leakage of the electrolyte from the flow paths, the packing 60 is interposed between the separator 11 and the ion exchange membrane 120.

[0082] Here, when the electrolyte flows through the flow path under high pressure, a contact pressure distribution between the separator and the insulating packing tends to vary depending on position. Accordingly, when an insulating packing having a uniform thickness different from the above-described configuration is used, a sufficient sealing effect cannot be obtained in a region where the contact pressure is low. As a result, leakage of the electrolyte may occur. In order to solve this problem, each of the above configurations is employed in the present embodiment.

[0083] Here, since the separators 11 are fixed to each other by a fastening structure of a bolt and a nut, a contact pressure of about several MPa is applied between the separator 11 and the insulating packing (packing 60). When the electrolyte is caused to flow through the electrolysis cell 12 in this state, the above-described contact pressure decreases due to fluid pressure, and the contact pressure becomes close to 0 depending on the location. In a case where an insulating packing having a uniform thickness is used, a gap between the packing 60 and the separator 11 is not sufficiently reduced in a region where the contact pressure is low, and leakage of the electrolyte may occur. In particular, the contact pressure tends to be low in a portion of the arc packing 302 in contact with the first diffusion guide portion 208 and the first convergence guide portion 207, and a portion of the triangular packing 303 extending to the oblique sides of the first diffusion flow path 206 and the first convergence flow path 205, respectively. However, according to the above-described configuration, the packing 60 is set to have a thickness more than that of other portions in a region where the contact pressure is low. Specifically, in the arc packing 302, the thickness of the arc packing 302 in a state before elastic deformation is set to be more than the gap between the first diffusion guide portion 208 and the ion exchange membrane 120, and in the triangular packing 303, the thickness of the triangular packing 303 is set to be more than the thickness of the packing main body 301. Accordingly, a sufficient contact pressure with the separator 11 can be ensured in each portion. As a result, sealing performance of the packing 60 is improved, and leakage of the electrolyte can be further suppressed. Therefore, the electrolysis cell 12 can be stably operated over a long period of time.

[0084] According to the above-described configuration, in the arc packing 302 where the contact pressure becomes low, the thickness of the arc packing 302 is set to be more than the thickness of the packing main body 301. This makes it possible to ensure a sufficient contact pressure between the arc packing 302 and the separator 11. As a result, sealing performance of the packing 60 is improved, and leakage of the electrolyte can be further suppressed.

[0085] According to the above-described configuration, in the load application test, a material capable of maintaining, 1 second after the load is released, a contact pressure of 96% or more of a contact pressure at full load is selected as the insulating packing (packing 60). Accordingly, the insulating packing can immediately recover its initial shape in response to changes in the contact pressure when the electrolysis cell 12 is started and stopped. Therefore, regardless of whether the electrolysis cell 12 is being started, operated, or stopped, it is possible to further reduce a possibility that leakage of the electrolyte occurs. As a result, the electrolysis cell 12 can be stably operated over a long period of time.

[0086] According to the above-described configuration, in the load application test, a material for which an elastic compression displacement amount 5 seconds after the load is released is 90% or less of an elastic compression displacement amount at full load is selected as the insulating packing. Accordingly, the insulating packing can immediately recover its initial shape in response to changes in the contact pressure when the electrolysis cell 12 is started and stopped. Therefore, regardless of whether the electrolysis cell 12 is being started, operated, or stopped, it is possible to further reduce a possibility that leakage of the electrolyte occurs. As a result, the electrolysis cell 12 can be stably operated over a long period of time.

[0087] According to the above-described configuration, ethylene propylene diene rubber having a hardness of 50 or more and 60 or less is used as the material for the insulating packing. Accordingly, the insulating packing can immediately recover its initial shape in response to changes in the contact pressure when the electrolysis cell 12 is started and stopped. Therefore, regardless of whether the electrolysis cell 12 is being started, operated, or stopped, it is possible to further reduce a possibility that leakage of the electrolyte occurs. As a result, the electrolysis cell 12 can be stably operated over a long period of time.

[0088] According to the above-described configuration, it is possible to provide the electrolyzer 1 including the electrolysis cell 12 in which leakage of the electrolyte is further suppressed.

[0089] (Other Embodiments)Although the embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the specific configuration is not limited to the embodiments and the present disclosure also includes design changes and the like without departing from the gist of the present disclosure.

[0090] For example, as a modification example of the separator 11, a configuration shown in FIG. 9 may be employed. In the example of the figure, an accommodation groove 401 that accommodates a part of the packing main body 301 is formed in the separator main body 201.

[0091] According to the above-described configuration, the accommodation groove 401 that accommodates a part of the packing main body 301 in the thickness direction is formed in the separator main body 201. As a result, a leakage path between the packing main body 301 and the separator 11 can be made more complex, so that it is possible to further reduce the possibility of leakage of the electrolyte. In addition, when the electrolysis cell 12 is assembled, alignment between the separator 11 and the packing main body 301 can be facilitated. Similarly, during operation, it is possible to reduce a possibility of positional displacement occurring between the separator 11 and the packing main body 301.

[0092] As a further modification example, a configuration shown in FIG. 10 may be employed. In the example of the figure, the separator 11 is further provided with a first protruding portion 501, a second protruding portion 502, a third protruding portion 503, and a fourth protruding portion 504. A plurality of first protruding portions 501 are provided at intervals in a circumferential direction on a part of a peripheral edge portion of the first discharge hole 202. A plurality of second protruding portions 502 are provided at intervals in a circumferential direction on a part of a peripheral edge portion of the first supply hole 203. The third protruding portion 503 is provided in the straight section 209 on the first discharge hole 202 side, and the fourth protruding portion 504 is provided in the straight section 209 on the first supply hole 203 side. A plurality of third protruding portions 503 and a plurality of fourth protruding portions 504 are provided at intervals in a direction intersecting a direction in which the straight section 209 extends. That is, the third protruding portions 503 and the fourth protruding portions 504 are respectively provided on an upstream side and a downstream side of the main flow path 204a.

[0093] According to this configuration, even when the ion exchange membrane 120 sinks toward one of the separators 11 for some reason, the first protruding portions 501, the second protruding portions 502, the third protruding portions 503, and the fourth protruding portions 504 can support the ion exchange membrane 120. Therefore, a possibility that the ion exchange membrane 120 blocks the flow path is reduced, and pressure loss of the fluid can be significantly reduced. Note that a configuration in which only the first protruding portions 501 and the second protruding portions 502 are provided and the third protruding portions 503 and the fourth protruding portions 504 are not provided may be employed. Conversely, only the third protruding portions 503 and the fourth protruding portions 504 may be provided. The first protruding portions 501 to the fourth protruding portions 504 may be provided on a plate-shaped thickness adjustment plate stacked on the ion exchange membrane 120, instead of being provided on the separator 11. In this case, it is only necessary to newly install a thickness adjustment plate or replace an existing thickness adjustment plate not having the first protruding portions 501 to the fourth protruding portions 504 with another thickness adjustment plate having the first protruding portions 501 to the fourth protruding portions 504. Since it is not necessary to initially provide the first protruding portions 501 to the fourth protruding portions 504 on the separator 11, which is an expensive component that is difficult to process, a significant cost advantage can be obtained.

[0094] <Supplementary Note>The electrolysis cell 12 and the electrolyzer 1 described in each embodiment can be understood as follows, for example.

[0095] (1) An electrolysis cell 12 according to a first aspect includes a pair of separators 11, an anion exchange membrane (ion exchange membrane 120) disposed between the pair of separators 11, and an insulating packing (packing 60) provided between the anion exchange membrane and each of the separators 11, in which each separator 11 has a separator main body 201 having a rectangular plate shape and having a first surface facing one side in a thickness direction and a second surface facing the other side in the thickness direction, a first supply hole 203 and a first discharge hole 202 that are formed on one diagonal line of the separator main body 201 on the first surface and penetrate the separator main body 201 from the first surface toward the second surface, a main flow path 204a having a plurality of first groove portions 204 that are formed in a region between the first supply hole 203 and the first discharge hole 202, extend in a longitudinal direction of the separator main body 201, and are arranged at intervals from each other in a width direction orthogonal to the longitudinal direction, a first diffusion flow path 206 that extends from the first supply hole 203 to the first groove portions 204, is recessed from the first surface side toward the second surface side, and has a trapezoidal shape in which a dimension in the width direction gradually increases from the first supply hole 203 toward the first groove portions 204 as viewed from the first surface side, a first convergence flow path 205 that extends from the first groove portions 204 to the first discharge hole 202, is recessed from the first surface side toward the second surface side, and has a trapezoidal shape in which a dimension in the width direction gradually decreases from the first groove portions 204 toward the first discharge hole 202 as viewed from the first surface side, a first diffusion guide portion 208 that is provided in the first diffusion flow path 206, protrudes from the second surface side toward the first surface side, and extends radially from the first supply hole 203 to guide a fluid from the first supply hole 203 to the first groove portions 204, and a first convergence guide portion 207 that is provided in the first convergence flow path 205, protrudes from the second surface side toward the first surface side, and extends radially from the first discharge hole 202 to guide the fluid from the first groove portions 204 to the first discharge hole 202, and in which the insulating packing has a packing main body 301 that is disposed outside the main flow path 204a, the first diffusion flow path 206, and the first convergence flow path 205 and has an annular shape as viewed from the first surface side, an arc packing 302 that is formed inside the packing main body 301, extends so as to bridge each of the first diffusion guide portion 208 and the first convergence guide portion 207, and has an arc shape surrounding each of the first supply hole 203 and the first discharge hole 202 from an outer peripheral side, and a triangular packing 303 that is formed inside the packing main body 301 and extends to oblique sides of the first diffusion flow path 206 and the first convergence flow path 205, and in which, in the arc packing 302 in a state before the arc packing 302 is sandwiched between one of the separators 11 and the anion exchange membrane and elastically deformed, a thickness of the arc packing 302 is set to be greater than a gap between the first diffusion guide portion 208 and the anion exchange membrane.

[0096] According to the above-described configuration, the thickness of the packing 60 is set to be greater in a region where the contact pressure is low than in other portions. As a result, a sufficient contact pressure with the separator 11 can be ensured in each portion. As a result, sealing performance of the packing 60 is improved, and leakage of the electrolyte can be further suppressed.

[0097] (2) An electrolysis cell 12 according to a second aspect is the electrolysis cell 12 according to (1), in which the thickness of the arc packing 302 is set to be greater than the gap between the first diffusion guide portion 208 and the anion exchange membrane (ion exchange membrane 120) by an amount of 0.1 mm or more and 1.0 mm or less.

[0098] According to the above-described configuration, in the arc packing 302 where the contact pressure becomes low, the thickness of the arc packing 302 is set to be greater than the thickness of the packing main body 301. This makes it possible to ensure a sufficient contact pressure between the arc packing 302 and the separator 11. As a result, sealing performance of the packing 60 is improved, and leakage of the electrolyte can be further suppressed.

[0099] (3) An electrolysis cell 12 according to a third aspect is the electrolysis cell 12 according to (1) or (2), in which an accommodation groove 401 that accommodates a part of the packing main body 301 is formed in the separator main body 201.

[0100] According to the above-described configuration, the accommodation groove 401 that accommodates a part of the packing main body 301 in the thickness direction is formed in the separator main body 201. As a result, a leakage path between the packing main body 301 and the separator 11 can be made more complex, so that it is possible to further reduce the possibility of leakage of the electrolyte.

[0101] (4) An electrolysis cell 12 according to a fourth aspect is the electrolysis cell 12 according to any one aspect of (1) to (3), in which the insulating packing is formed of a material for which, in a repeated load application test with a total load of 500 N or more, when an elastic compression displacement amount at a maximum load of 500 N is defined as 100%, an elastic compression displacement amount 5 seconds after releasing the load is 90% or less of an elastic compression displacement amount at a load of 500 N.

[0102] According to the above-described configuration, in the load application test, a material for which an elastic compression displacement amount 5 seconds after the load is released is 90% or less of an elastic compression displacement amount at full load is selected as the insulating packing. As a result, the insulating packing can immediately recover its initial shape in response to changes in the contact pressure when the electrolysis cell 12 is started and stopped.

[0103] (5) An electrolysis cell 12 according to a fifth aspect is the electrolysis cell 12 according to any one aspect of (1) to (4), in which the insulating packing (packing 60) is formed of ethylene propylene diene rubber having a hardness of 50 or more and 60 or less.

[0104] According to the above-described configuration, ethylene propylene diene rubber having a hardness of 50 or more and 60 or less is used as the material for the insulating packing. As a result, the insulating packing can immediately recover its initial shape in response to changes in the contact pressure when the electrolysis cell 12 is started and stopped.

[0105] (6) An electrolysis cell 12 according to a sixth aspect is the electrolysis cell 12 according to (1) or (5), in which the separator 11 further includes a plurality of first protruding portions 501 provided at intervals in a circumferential direction along a peripheral edge of the first discharge hole 202, a plurality of second protruding portions 502 provided at intervals in the circumferential direction along a peripheral edge of the first supply hole 203, a plurality of third protruding portions 503 provided on an upstream side of the main flow path 204a, and a plurality of fourth protruding portions 504 provided on a downstream side of the main flow path 204a, the third protruding portions 503 and the fourth protruding portions 504 being arranged at intervals from each other in a direction intersecting the main flow path 204a.

[0106] According to the above-described configuration, even when the ion exchange membrane 120 sinks toward one of the separators 11 for some reason, the first protruding portions 501, the second protruding portions 502, the third protruding portions 503, and the fourth protruding portions 504 can support the ion exchange membrane 120.

[0107] (7) An electrolyzer 1 according to a seventh aspect includes the electrolysis cell 12 according to any one aspect of (1) to (6), an electrolyte supply unit 20 configured to supply an electrolyte to the electrolysis cell 12, and a power supply section 30 configured to apply a voltage to the electrolysis cell 12.

[0108] According to the above-described configuration, it is possible to provide the electrolyzer 1 including the electrolysis cell 12 in which leakage of the electrolyte is further suppressed.INDUSTRIAL APPLICABILITY

[0109] According to the present disclosure, it is possible to provide an electrolysis cell and an electrolyzer in which leakage of an electrolyte is further suppressed.REFERENCE SIGNS LIST

[0110] 1 Electrolyzer10 Electrolysis cell stack11 Separator11a First separator11b Second separator11c Third separator11d Fourth separator11e Fifth separator11h1, 11h3 First insertion hole11h2, 11h4 Second insertion hole12 Electrolysis cell12a First electrolysis cell12b Second electrolysis cell12c Third electrolysis cell12d Fourth electrolysis cell13, 13' First flow path portion13o, 13o', 14o, 14o' Flow outlet14, 14' Second flow path portion15 First structure16 Second structure20 Electrolyte supply unit21 Hydrogen gas-liquid separation device22 First pump23 Hydrogen recovery unit24 First electrolyte supply unit26 Oxygen gas-liquid separation device27 Second pump28 Oxygen recovery unit29 Second electrolyte supply unit30 Power supply section65 First insulating member66 Second insulating member67 First end plate68 Second end plate63 First insulator47h1, 47h2, 48h1, 48h2 Hole64 Second insulator50 Support portion51 First ion exchange membrane52 Second ion exchange membrane60 Packing61 First current collector62 Second current collector110a First inner surface110b Second inner surface111 First end portion112 Second end portion120 Ion exchange membrane120a First surface120b Second surface120e Outer edge portion121 Cathode121a Cathode catalyst layer121b Cathode current collector122 Anode122a Anode catalyst layer122b Anode current collector130, 130', 140, 140' Pipe portion150, 150a, 150b, 150c, 160 Notch portion151 Mesh member151a First mesh member151b Second mesh member151c Third mesh member151d Fourth mesh member152, 153 Conductive mesh201 Separator main body201a First surface201b Second surface202 First discharge hole203 First supply hole204 First groove portion205 First convergence flow path206 First diffusion flow path207 First convergence guide portion208 First diffusion guide portion209 Straight section211 Second supply hole210 Second discharge hole212 Second groove portion301 Packing main body302 Arc packing303 Triangular packing401 Accommodation groove501 First protruding portion502 Second protruding portion503 Third protruding portion504 Fourth protruding portionC Central portionD1 First directiondl One sidedr Other sideEs ElectrolyteL1, L1', L2, L2' Piping lineS Internal spaceS1 GapSa Cathode chamberSb Anode chamber  

Claims

1. An electrolysis cell comprising:a pair of separators;an anion exchange membrane disposed between the pair of separators; andan insulating packing provided between the anion exchange membrane and each of the separators,wherein each of the separators includesa separator main body having a rectangular plate shape and having a first surface facing one side in a thickness direction and a second surface facing the other side in the thickness direction,a first supply hole and a first discharge hole that are formed on one diagonal line of the separator main body on the first surface and penetrate the separator main body from the first surface toward the second surface,a main flow path having a plurality of first groove portions that are formed in a region between the first supply hole and the first discharge hole, extend in a longitudinal direction of the separator main body, and are arranged at intervals from each other in a width direction orthogonal to the longitudinal direction,a first diffusion flow path that extends from the first supply hole to the first groove portions, is recessed from the first surface side toward the second surface side, and has a trapezoidal shape in which a dimension in the width direction gradually increases from the first supply hole toward the first groove portions as viewed from the first surface side,a first convergence flow path that extends from the first groove portions to the first discharge hole, is recessed from the first surface side toward the second surface side, and has a trapezoidal shape in which a dimension in the width direction gradually decreases from the first groove portions toward the first discharge hole as viewed from the first surface side,a first diffusion guide portion that is provided in the first diffusion flow path, protrudes from the second surface side toward the first surface side, and extends radially from the first supply hole to guide a fluid from the first supply hole to the first groove portions, anda first convergence guide portion that is provided in the first convergence flow path, protrudes from the second surface side toward the first surface side, and extends radially from the first discharge hole to guide the fluid from the first groove portions to the first discharge hole,the insulating packing includesa packing main body that is disposed outside the main flow path, the first diffusion flow path, and the first convergence flow path, and has an annular shape as viewed from the first surface side,an arc packing that is formed inside the packing main body, extends so as to bridge the first diffusion guide portion and the first convergence guide portion, and has an arc shape surrounding each of the first supply hole and the first discharge hole from an outer peripheral side, anda triangular packing that is formed inside the packing main body, and extends to oblique sides of the first diffusion flow path and the first convergence flow path, andin the arc packing in a state before the arc packing is sandwiched between one of the separators and the anion exchange membrane and elastically deformed, a thickness of the arc packing is set to be greater than a gap between the first diffusion guide portion and the anion exchange membrane.

2. The electrolysis cell according to Claim 1, wherein the thickness of the arc packing is set to be greater than the gap between the first diffusion guide portion and the anion exchange membrane by an amount of 0.1 mm or more and 1.0 mm or less.

3. The electrolysis cell according to Claim 1 or 2, wherein an accommodation groove that accommodates a part of the packing main body is formed in the separator main body.

4. The electrolysis cell according to Claim 1 or 2, wherein the insulating packing is formed of a material for which, in a repeated load application test with a total load of 500 N or more, when an elastic compression displacement amount at a maximum load of 500 N is defined as 100%, an elastic compression displacement amount 5 seconds after releasing the load is 90% or less of an elastic compression displacement amount at a load of 500 N.

5. The electrolysis cell according to Claim 1 or 2, wherein the insulating packing is formed of ethylene propylene diene rubber having a hardness of 50 or more and 60 or less.

6. The electrolysis cell according to Claim 1 or 2, wherein the separator further includes a plurality of first protruding portions and a plurality of second protruding portions that are provided at intervals in a circumferential direction along peripheral edges of the first discharge hole and the first supply hole, and a plurality of third protruding portions and a plurality of fourth protruding portions that are provided respectively on an upstream side and a downstream side of the main flow path and arranged at intervals from each other in a direction intersecting the main flow path.

7. An electrolyzer comprising:the electrolysis cell according to Claim 1 or 2;an electrolyte supply unit configured to supply an electrolyte to the electrolysis cell; anda power supply section configured to apply a voltage to the electrolysis cell. 

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