Electrolytic cell

Abstract

To provide an electrolytic tank that can suppress a local deformation of a diaphragm.SOLUTION: An electrolytic tank according to an embodiment of the present invention comprises an anode, a cathode, a diaphragm, and a support frame. In the electrolytic tank, at least an edge of at least one of the anode and the cathode is overlapped with the sealed surface of the support frame in a plane view.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electrolytic cell, and in particular to an electrolytic cell comprising an anode, a cathode, a diaphragm, and a support frame. [Background technology]

[0002] Currently, electrolysis is used in various industries. Electrolytic cells are used to perform electrolysis, i.e., electrolysis. Electrolytic cells come in a variety of types depending on their use, but they at least have an anode and a cathode. For example, electrolytic cells that perform electrolysis of an aqueous solution of sodium chloride can extract chlorine, hydrogen, and sodium hydroxide (so-called caustic soda), and are used to produce the raw materials that are the basis of the chemical industry. They are also used to electrolyze an aqueous alkaline solution used in hydrogen production.

[0003] In the electrolytic cell, a diaphragm is often further provided to prevent mixing of the substances produced at the anode and the cathode. The process of electrolyzing a sodium chloride solution using an ion exchange membrane as a diaphragm is also called "ion exchange membrane method for salt electrolysis". [Prior art documents] [Patent documents]

[0004] International Publication No. 2018 / 139613 Summary of the Invention [Problem to be solved by the invention]

[0005] There are various types of electrolytic cells used in the above-mentioned ion exchange membrane method salt electrolysis, among which the zero-gap type is the mainstream. A zero-gap type electrolytic cell 100' mainly comprises an anode 200B', a cathode 200A', a diaphragm 300', a support 400' for supporting the electrodes, and a gasket 500'. In the zero-gap type electrolytic cell 100', the diaphragm 300' is sandwiched between the anode 200B' and the cathode 200A' and tightly adhered to reduce the distance between the electrodes, thereby reducing the electrolyte resistance and power consumption (see FIG. 7).

[0006] Here, the inventors of the present application realized that there are still problems to be overcome in the conventional zero-gap electrolytic cell, and found the need to take measures to address these problems. Specifically, in such an electrolytic cell 100', the support 400' can be configured so that the support frame 410' located at the periphery forms an internal space, i.e., the support frame 410' surrounds the internal space. The electrode can be accommodated in this internal space, and the diaphragm 300' can be arranged to cover the electrode. From the viewpoint of production efficiency, etc., it is preferable to make the planar size of the electrode and the planar size surrounded by the inner edge 412' of the support frame 410' the same, but this adjustment is not easy. Since such size adjustment is not easy, it becomes difficult to adjust the positioning of the end edge 211' of the electrode (i.e. the edge forming the outermost edge of the electrode) along the inner edge 412' of the support frame, and there is a risk of a gap being generated between the inner edge 412' of the support frame and the end edge 211' of the electrode. If such a gap occurs, the diaphragm 300' located on the electrode may be partially inserted, which may cause the local deformation of the diaphragm 300' to become relatively large. As a result, the electrolytic cell 100' may not operate properly.

[0007] The present invention has been made in view of the above circumstances. That is, a main object of the present invention is to provide an electrolytic cell in which the attachment positions of the electrodes can be appropriately adjusted to suppress local deformation of the diaphragm. [Means for solving the problem]

[0008] In order to achieve the above object, in one embodiment of the present invention, An electrolytic cell comprising an anode, a cathode, a diaphragm, and a support frame, An electrolytic cell is provided in which, in a plan view, at least an end edge of at least one of the anode and cathode electrodes overlaps a sealing surface of the support frame. Effect of the Invention

[0009] According to the electrolytic cell according to one embodiment of the present invention, local deformation of the diaphragm can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded perspective view showing a schematic diagram of an electrolytic cell according to one embodiment of the present invention. [Figure 2A] FIG. 2A is a plan view that illustrates a schematic diagram of an electrolytic cell (electrolytic cell unit) according to one embodiment of the present invention. [Figure 2B] FIG. 2B is a cross-sectional view showing a schematic diagram of an electrolytic cell (electrolytic cell unit) according to one embodiment of the present invention taken along line II in FIG. 2A. [Figure 2C] FIG. 2C is a cross-sectional view showing a schematic diagram of an electrolytic cell (electrolytic cell unit) according to one embodiment of the present invention taken along line II-II in FIG. 2A. [Diagram 3] FIG. 3 is a schematic diagram of a characteristic portion of an electrolytic cell according to one embodiment of the present invention. [Figure 4A] FIG. 4A is an enlarged cross-sectional view of an end edge portion of an electrode of an electrolytic cell according to one embodiment of the present invention. [Figure 4B] FIG. 4B is an enlarged cross-sectional view of an end edge portion of an electrode of an electrolytic cell according to one embodiment of the present invention. [Figure 4C] FIG. 4C is an enlarged cross-sectional view of an end edge portion of an electrode of an electrolytic cell according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram for illustrating the configuration of the electrolytic cell. [Figure 6]FIG. 6 is a perspective view showing an example of a conductive elastic body used in an electrolytic cell. [Figure 7] FIG. 7 is a cross-sectional view that illustrates a conventional electrolytic cell (electrolytic cell unit). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an electrolytic cell according to an embodiment of the present invention will be described in more detail with reference to the drawings. Various elements in the drawings are merely shown as schematic and illustrative examples for the purpose of understanding the present invention, and the outline and dimensional ratios may differ from those of the actual parts.

[0012] In this specification, the term "electrolytic cell" refers, in a broad sense, to an apparatus for performing electrolysis, and in a narrow sense, to an apparatus including at least an anode, a cathode, and a diaphragm disposed between the electrodes. In this specification, the term "electrode for electrolysis" refers, in a broad sense, to an electrode used in an apparatus for performing electrolysis, and in a narrow sense, to an anode and / or a cathode used in such an apparatus.

[0013] When the electrolytic cell is in use, it is often installed and used such that the extension direction of the short sides of the electrolytic cell shown in Fig. 1 is vertical or the extension direction of the long sides is horizontal. Therefore, the orientation of the cell and its components may be different when the electrolytic cell is in use (particularly when the electrolytic cell is in operation with the units constituting the electrolytic cell combined) and when it is not in use (particularly when it is not in operation before the units constituting the electrolytic cell are combined).

[0014] The term "plan view" in this specification refers to the shape of the object when viewed from above or below along the thickness direction based on the extension direction of the diaphragm and electrodes that constitute the electrolytic cell. In addition, the term "cross-sectional view" in this specification refers to the state when viewed from a direction approximately perpendicular to the thickness direction of the support and electrodes that constitute the electrolytic cell. The "upper and lower directions" and "left and right directions" that are used directly or indirectly in this specification correspond to the upper and lower directions and left and right directions in the drawings, respectively. Unless otherwise specified, the same symbols or symbols indicate the same members or parts or the same meanings. In a preferred embodiment, the vertical downward direction (i.e., the direction in which gravity acts) can be considered to correspond to the "downward direction", and the opposite direction can be considered to correspond to the "upward direction".

[0015] Various numerical ranges mentioned in this specification are intended to include the lower and upper limit values ​​themselves. That is, for example, a numerical range such as 1 to 10 is interpreted as including the lower limit "1" and the upper limit "10."

[0016] First, the basic configuration of the electrolytic cell that is the premise of the present invention will be described, and then the features of the present invention will be described. In the following description, electrodes for the electrolytic cell, i.e., electrodes for electrolysis, will be simply referred to as "electrodes" or, more specifically, as "anodes" or "cathodes."

[0017] [Basic configuration of electrolytic cell] The basic configuration of an electrolytic cell according to one embodiment of the present invention will be described below. The electrolytic cell comprises at least an anode, a cathode, a diaphragm disposed between the electrodes, a support, and a gasket. The anode and the cathode are electrodes for externally applying electrical energy to the electrolyte solution. Typically, the anode is an electrode connected to the positive electrode of an external power source, and is an electrode where an oxidation reaction can occur during operation of the electrolytic cell. On the other hand, the cathode is an electrode typically connected to the negative electrode of an external electrode, and is an electrode where a reduction reaction can occur during operation of the electrolytic cell.

[0018] The diaphragm is typically a member that separates the anode chamber from the cathode chamber. Preferably, the diaphragm is provided to prevent mixing of the material produced at the anode and the material produced at the cathode. In the present invention, the diaphragm may be one that is conventionally used in electrolysis. For example, the diaphragm is an ion exchange membrane. As only one example, in electrolytic cells used in the soda industry, a cation exchange membrane may be used as the diaphragm.

[0019] The electrolytic cell may further include a conductive elastic body. The conductive elastic body contributes to the passage of current between the electrodes due to its "conductivity," while being capable of exerting a pressing force against the electrodes due to its "elasticity." In other words, the conductive elastic body corresponds to a conductive part capable of exerting a reaction force in the electrolytic cell, and has at least a structure capable of elastic deformation in order to provide such a reaction force.

[0020] An exemplary configuration of an electrolytic cell is shown in FIG. 5. As shown in the figure, in the electrolytic cell, a conductive elastic body is used for an electrode assembly at least composed of an anode, a cathode, and an ion exchange membrane between the electrodes. In such an electrolytic cell, the reaction force of the conductive elastic body is used to press the electrode assembly at least composed of an anode, a cathode, and an ion exchange membrane between the electrodes. Specifically, the conductive elastic body is used in a state in which it is subjected to elastic deformation on the back side of the electrode assembly, and a pressing force is applied to the electrode assembly by the elastic force (i.e., the reaction force) provided by the conductive elastic body. In particular, the conductive elastic body subjected to elastic deformation acts to apply a pressing force from one electrode toward the other electrode, thereby promoting the close contact of the electrode assembly. In other words, the presence of the conductive elastic body brings about a close contact between the anode, the ion exchange membrane, and the cathode, and the electrolytic cell can function favorably as a so-called "zero gap" type.

[0021] The conductive elastic body used in the electrolytic cell may have any form as long as it generates an elastic repulsive force. For example, the conductive elastic body may have various forms such as an elastic cushion or an elastic mat (for example, a member made of a metal coil body, a metal nonwoven fabric, a knitted or woven fabric made of a metal wire, etc.), or a leaf spring. As only one specific example, the conductive elastic body 700 may have an attachment opening 740 and a wavy curved elastic part 720 extending from a fixing part 710 as shown in FIG. 6. The conductive elastic body is used in the electrolytic cell in a state in which it is subjected to elastic deformation so as to develop spring characteristics. More specifically, for example, the conductive elastic body is provided in the electrolytic cell in a state in which it is subjected to deformation so that the wavy curve of the elastic part is reduced. In the conductive elastic body thus deformed, a stress acts on the conductive elastic body to take the original shape, and a repulsive force is developed as a spring characteristic. In a large electrolytic cell, a conductive elastic body is often provided as a plurality of conductive elastic bodies rather than being used singularly.

[0022] In the electrolytic cell, the electrodes may be made of, for example, a conductive substrate having liquid permeability. In this regard, it is preferable that at least one of the anode and the cathode has a conductive porous substrate. In other words, at least one of the anode and the cathode may be a mesh opening electrode having mesh openings. Although these are merely examples, the electrodes may be made of, for example, expanded metal, wire mesh (plain weave mesh, twill weave mesh), punched metal, or the like.

[0023] In a preferred embodiment, both the anode and the cathode may have a conductive porous substrate. For example, both electrodes may be made of expanded metal or plain weave mesh, or one electrode may be made of expanded metal and the other electrode may be made of plain weave mesh. That is, both the anode and the cathode may have expanded mesh or plain weave mesh, or one of the anode and the electrode may have expanded mesh and the other may have plain weave mesh. From the viewpoint of being able to exhibit corrosion resistance, each of the anode and the cathode may comprise at least one selected from the group consisting of titanium, nickel, stainless steel, tantalum, zirconium, niobium, and the like. In addition, each of such anodes and cathodes may be supported with a suitable catalyst. The opening ratio of the conductive porous substrate is not particularly limited, but may be about 20% to 90%, for example, 30% to 80%, 40% to 75%, or 50% to 75%, etc.

[0024] The electrolytic cell is preferably a zero-gap type, and has characteristics suitable for such a zero-gap type. As one of such characteristics, the anode and cathode are characterized in terms of so-called "hardness" and "softness" such as the rigidity and flexibility of the electrode material. Specifically, it is preferable that one of the anode and cathode is relatively flexible with respect to the other, and conversely, the other is relatively rigid with respect to the one. As a result, the relatively flexible electrode can bend by receiving the reaction force of the conductive elastic body, while the relatively rigid electrode can receive the bending through the ion exchange membrane. If the anode and cathode are relatively different from this viewpoint, the mutual adhesion between the anode, the ion exchange membrane, and the cathode becomes more suitable, and the electrolytic cell can function more suitably as a "zero-gap type". This is particularly true when the electrolytic cell is large. That is, it is particularly true when the electrode main surface that requires pressing for zero gap is large, as typified by the zero-gap type salt electrolysis.

[0025] To obtain a larger amount of the desired electrolysis product, a larger electrolytic cell is used, and the main surfaces of the electrodes (particularly, the main surfaces where the anode and cathode face each other) are accordingly larger. A large zero-gap electrolytic cell is preferably composed of a plurality of electrolytic cell units, and each of the electrolytic cell units has a large electrode main surface on both opposing side surfaces. As an example, a so-called "bipolar" electrolytic cell is described with reference to FIG. 1. A cathode 200A (e.g., a cathode surface made of expanded metal) is provided on one of the opposing side surfaces of the electrolytic cell unit, and an anode 200B (e.g., an anode surface made of expanded metal) is provided on the other of the opposing side surfaces. In the electrolytic cell, such electrolytic cell units are connected in a plurality of layers so as to be stacked on top of each other via ion exchange membranes 300 (particularly cation exchange membranes). In particular, adjacent electrolytic cell units are stacked so that the cathode surface of one electrolytic cell unit faces the anode surface of the other electrolytic cell unit. In this way, an electrolytic cell is constructed by combining a plurality of electrolytic cell units via ion exchange membranes. Note that an electrolytic cell constructed from a plurality of electrolytic cell units is not limited to a "bipolar type" and may be a "monopolar type". In other words, the electrode cell units constituting the electrolytic cell are not limited to bipolar type electrolytic cell units having an anode portion and a cathode portion on both opposing sides, but may be "monopolar type" electrolytic cell units having only an anode portion and only a cathode portion on both opposing sides. In such a case, an electrolytic cell can be constructed by combining electrolytic cell units having only an anode portion and an electrolytic cell unit having only a cathode portion so as to be alternately arranged via ion exchange membranes.

[0026] An electrolytic cell composed of electrolytic cell units has a relatively large electrode main surface size, which is preferable because the desired electrolytic reaction occurs through the large electrode surface, but it is difficult to maintain the flatness of the electrode surface. Specifically, the larger the electrode main surface is, the more likely it is that the effect of bending due to its own weight cannot be ignored, and the attachment to the electrode supporter also has an effect, making it difficult to obtain a completely flat electrode main surface. For example, in the electrolytic cell 100 illustrated in FIG. 1, the main surface size of the anode surface and the cathode surface is on the order of meters rather than on the order of several centimeters. Even if the electrodes are made rigid to provide a more suitable flat surface, such a large electrode main surface has a flatness of, for example, about ±0.5 mm to 1.0 mm for the above reasons, and is difficult to obtain a completely flat surface (i.e., a flatness of 0 mm). In other words, in a large electrolytic cell, the rigid electrode main surface appears flat macroscopically, but tends to have local unevenness microscopically.

[0027] When electrodes that are not completely flat are brought into close contact with each other through an ion exchange membrane, the unevenness may impair the uniformity of the current distribution. Therefore, in a suitable electrolytic cell, the electrode that is paired with a rigid electrode is a soft flexible electrode. This allows the flexible electrode to bend so as to follow the unevenness of the rigid electrode surface even if the electrodes are tightly brought into close contact with each other through an ion exchange membrane, and as a result, non-uniformity of the current distribution can be more suitably prevented. As an example, the anode may be made of a relatively hard rigid expanded metal, while the cathode may be made of a relatively soft flexible expanded metal. A conductive elastic body may be provided on the back side of the flexible expanded metal of the cathode that is combined with the rigid expanded metal of the anode through the ion exchange membrane. In such a case, the flexible expanded metal of the cathode is pressed toward the rigid expanded metal of the anode by the reaction force of the conductive elastic body, and at that time, the flexible expanded metal of the cathode can be locally displaced according to the flatness of the main surface of the rigid expanded metal of the anode. Therefore, even if the electrolytic cell units are fixed tightly and the reaction force of the conductive elastic body is large, the anode, ion exchange membrane, and cathode are suitably adhered to each other, and undesirable phenomena such as non-uniform current distribution are unlikely to occur.

[0028] Although not particularly limited, the relatively hard expanded metal may have a thickness of preferably about 0.2 to 2.0 mm, due to the "relative rigidity", and the width (step width) of the strands forming the pores, i.e., the openings, may be preferably about 0.2 to 2.0 mm. Similarly, although not particularly limited, the flexible expanded metal may have a thickness of preferably about 0.1 to 1.0 mm, more preferably about 0.1 to 0.5 mm, due to the "relative flexibility", and the width of the strands forming the pores, i.e., the openings, may be preferably about 0.1 to 2.0 mm, more preferably about 0.1 to 1.5 mm. When a wire mesh or punched metal is used as the flexible electrode, the thickness may be preferably about 0.1 to 1.0 mm, more preferably about 0.1 to 0.5 mm, due to the "relative flexibility", for example. In the case of a wire mesh, the wire diameter φ, which means the approximate diameter of the metal fibers constituting the wire mesh, may be preferably about 0.05 to 1.0 mm, more preferably about 0.1 to 0.5 mm. In the case of a punched metal, the non-opening length L between adjacent openings may be about 0.1 to 2.0 mm, more preferably about 0.1 to 1.5 mm.

[0029] As one example, the flexible cathode 200A made of expanded metal, the diaphragm 300, and the rigid anode 200B made of expanded metal are stacked in this order, and the conductive elastic body 700 is provided on the back side of the cathode 200A (i.e., the side opposite to the side on which the diaphragm 300 is provided). The conductive elastic body 700 is provided while being subjected to deformation so as to be constricted between the cathode 200A made of expanded metal and the cathode base, so that the elastic force of the conductive elastic body 700 is directly applied to the flexible cathode 200A made of expanded metal that is in direct contact with the elastic part of the conductive elastic body 700. As a result, the flexible cathode 200A made of expanded metal is biased so as to be pressed toward the rigid anode 200B made of expanded metal, and the flexible cathode 200A, the diaphragm 300, and the rigid anode 200B are brought into close contact with each other. In addition, the rigid anode itself, which is an electrode that is not in direct contact with the conductive elastic body, is fixed so as not to move to an electrode support body of the electrolytic cell unit, etc., and therefore acts to absorb the elastic force of the conductive elastic body, contributing to close contact.

[0030] As will be described later, the support constitutes the exterior of the electrolytic cell. As an example, a set of two supports constitutes the exterior of the electrolytic cell. Each support has a support frame located at the periphery and a bottom that is continuous with the support frame and forms an internal space (specifically, a recessed space). That is, in the support, the support frame is configured to surround the internal space (specifically, a recessed space) in a plan view. Based on this configuration, the two supports are arranged facing each other so that the sealing surfaces of the support frames sandwich the diaphragm and the gasket positioned on the sealing surfaces.

[0031] [Characteristics of the present invention] The following describes the characteristics of an electrolytic cell according to one embodiment of the present invention. The inventors of the present invention have conducted extensive research into a solution for suppressing local deformation of the diaphragm caused by a gap between the inner edge of the support frame and the end edge of the electrode. As a result, the inventors have devised an electrolytic cell according to one embodiment of the present invention having the following characteristics.

[0032] An electrolytic cell 100 according to one embodiment of the present invention comprises at least an anode 200B, a cathode 200A, a diaphragm 300 disposed between these electrodes, a support 400, and a gasket 500 (see Figs. 1 to 3). One embodiment of the present invention is characterized by the positional relationship between the electrodes (particularly the end edges of the electrodes) and the support frame among the components of the electrolytic cell described above in the section [Basic configuration of electrolytic cell]. In particular, in one embodiment of the present invention, at least the end edge 211 of at least one of the electrodes, the anode 200B and the cathode 200A, is positioned relative to the support frame in a plan view. 410 (See FIG. 3 in particular.) This is a technical feature of the electrolytic cell 100 according to one embodiment of the present invention.

[0033] Before describing the characteristic features of the present invention, the definitions of terms are given. In this specification, the term "end of the electrode" refers to the part that forms the outer edge or contour area of ​​the electrode. In this specification, the term "end edge of the electrode" refers to the end part of the electrode, particularly the most distal part of the electrode. That is, the end edge of the electrode is the edge itself that forms the "most" outer edge of the electrode, and indicates each side part that constitutes the electrode when viewed in a plan view. In this specification, the "sealing surface 411 of the support frame 410" refers to the surface that seals the support frames 410 together in a broad sense, and in a narrow sense, refers to the surface of the support frame 410 that has the function of preventing the electrolyte and generated gas inside the electrode chamber from leaking out to the outside.

[0034] In addition, in this specification, "arrangement so that the end edge of the electrode overlaps with the sealing surface of the support frame" refers to positioning the end edge of the electrode so that a part of the sealing surface 411 of the support frame and the end edge 211 of the electrode overlap each other as shown in Fig. 2A and Fig. 3 in a plan view. In other words, such an overlapping arrangement refers to positioning the end edge of the electrode so that a part of the sealing surface 411 of the support frame is covered by the end edge 211 of the electrode or the end edge 211 of the electrode covers a part of the sealing surface 411 of the support frame. Note that in one embodiment of the present invention, "overlapping" is also considered to occur when the end edge 211 of the electrode is located on the edge of the sealing surface 411 of the support frame, i.e., on the side that forms the sealing surface 411 of the support frame.

[0035] The electrolytic cell 100 according to one embodiment of the present invention has the above-mentioned technical features, and therefore can achieve the following technical effects.

[0036] Specifically, in one embodiment of the present invention, the end edge 211 of the electrode is arranged to overlap the sealing surface 411 of the support frame in a plan view (see FIG. 3). This overlapping arrangement results in the end edge 211 of the electrode being positioned outboard of the inner edge 412 of the support frame in a cross-sectional view, as compared to conventional electrolytic cells. From another perspective, as will be described below, the end edge 211 of the electrode is positioned at or on the sealing surface 411 of the support frame in a cross-sectional view.

[0037] Such an overlapping arrangement can be realized by making the size of the electrode larger than the size of the area surrounded by the inner edge 412 of the sealing surface 411 of the support frame 410 in a plan view. In this specification, the term "area surrounded by the inner edge 412 of the sealing surface 411 of the support frame 410" refers to the area surrounded by the support frame 410 in a broad sense, and refers to the area surrounded by the edge of the electrode chamber side among the edges constituting the sealing surface 411 of the support frame 410 in a narrow sense. By adopting such a configuration, an overlapping arrangement of the end edge 211 of the electrode and the sealing surface 411 of the support frame in a plan view is possible.

[0038] The overlapping arrangement makes it possible to prevent a gap from occurring between the inner edge 412 of the support frame and the end edge 211 of the electrode. This makes it possible to prevent the diaphragm 300 located on the electrode from partially entering the gap, thereby making it possible to suppress local deformation of the diaphragm 300. This suppression of local deformation of the diaphragm 300 makes it possible to operate the electrolytic cell 100 in a suitable manner.

[0039] Furthermore, in the conventional electrolytic cell 100', local deformation of the diaphragm 300' may occur. Such local deformation may cause the diaphragm 300' to bend in a V shape, which may cause load to accumulate at the bent portion of the diaphragm 300'. As a result, the diaphragm 300' itself may be damaged. In regard to this point, in the electrolytic cell 100 according to one embodiment of the present invention, local deformation of the diaphragm 300 can be suppressed, and therefore damage to the diaphragm 300 can also be suppressed.

[0040] In addition, the overlapping arrangement of the end edge 211 of the electrode and the sealing surface 411 of the support frame eliminates the need for precise position adjustment between the end edge 211 of the electrode and the support frame 410. This allows the electrode 200 to be placed on the support 400 efficiently and easily, thereby shortening the time required to assemble the electrolytic cell 100. In other words, the efficiency of the work of assembling the electrolytic cell 100 can also be improved.

[0041] The above describes the effects of the technical feature of one embodiment of the present invention (the overlapping arrangement of the end edge of the electrode and the sealing surface of the support frame). In the following, the technical feature of the present invention will be described with a focus on the positional relationship between the sealing surface 411 of the support frame 410 and the gasket 500.

[0042] As shown in Figures 2B, 2C and 3, in an electrolytic cell 100 according to an embodiment of the present invention, a gasket 500 is positioned on the sealing surface 411 of the support frame. Specifically, the gasket 500 is arranged to close the gap between the sealing surfaces 411 of the support frame in order to prevent the electrolyte in the electrode chamber or the generated gas from leaking to the outside. The gasket 500 has elasticity, and by utilizing elastic deformation due to compression, the occurrence of gaps between the sealing surfaces 411 of the support frame is suitably prevented. The larger the area that the gasket 500 covers on the sealing surface 411 of the support frame, the better the sealing characteristics of the gasket 500 will be, whereas the smaller the area that it covers, the worse the sealing characteristics may be.

[0043] Therefore, in order to suitably achieve the above-mentioned technical feature of the present invention (overlapping arrangement of the end edge of the electrode and the sealing surface of the support frame), it is preferable that the inner edge 510 of the gasket 500 is positioned outside the inner edge 412 of the sealing surface 411 of the support frame. In this specification, the "inner edge of the gasket" refers to the edge of the gasket facing the electrode chamber in which the electrolyte is present, as shown in Fig. 3.

[0044] In conventional electrolytic cells, the gasket is usually arranged flush with the inner edge of the support frame to prevent electrolyte from leaking from the electrode chamber to the outside. In contrast, in one embodiment of the present invention, the inner edge 510 of the gasket 500 is positioned outside the inner edge 412 of the sealing surface 411 of the support frame. In other words, the gasket 500 is positioned on a part of the sealing surface 411 of the support frame.

[0045] The position where the inner edge of the gasket 500 can be provided outside the inner edge 412 of the sealing surface 411 of the support frame is not particularly limited as long as the gasket 500 has sealing properties that prevent electrolyte and the like from leaking from the electrode chamber to the outside. For example, in a cross-sectional view, the distance between the inner edge of the gasket and the inner edge of the sealing surface of the support frame can be 30% or less, preferably 20% or less, and more preferably 10% or less of the distance between the inner edge of the support frame 410 and the outer edge facing it.

[0046] The gasket 500 used in the present invention may be one commonly used for electrolysis. For example, the gasket 500 is preferably made of an elastic material that is resistant to alkali and has high sealing properties. For example, the gasket 500 may be made of at least one resin material selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene rubber, butyl rubber, butadiene rubber, ethylene-propylene rubber (EPM rubber), ethylene-propylene-diene rubber (EPDM rubber), chloroprene rubber, silicone rubber, fluororubber, acrylic rubber, porous PTFE (polytetrafluoroethylene), etc.

[0047] In the following, in one embodiment of the present invention, possible overlapping modes between the end edge 211 of the electrode and the sealing surface 411 of the support frame will be described. As long as the end edge 211 of the electrode overlaps a part of the sealing surface 411 of the support frame, the mode is not particularly limited.

[0048] As an example, as shown in Figure 4A, the end edge 211 of the electrode may be positioned on the sealing surface 411 of the support frame, spaced apart from the sealing surface 411, in cross section. As another example, as shown in Figures 4B and 4C, the end edge 211 of the electrode may be positioned on the sealing surface 411 of the support frame, in cross section. That is, in one embodiment of the present invention, the end edge 211 of the electrode may be positioned on or above the sealing surface 411 of the support frame.

[0049] Of the above embodiments, it is preferable that the end edge 211 of the electrode is spaced apart from the sealing surface 411 of the support frame. In an embodiment in which the end edge 211 of the electrode is positioned so as to contact the sealing surface 411 of the support, a load is applied to the end edge 211 of the electrode during use, which may result in damage to the end edge 211 of the electrode. In contrast, when a spaced arrangement embodiment is adopted, a space is formed between the end edge 211 and the sealing surface 411 of the support frame. This makes it possible to suppress the application of a load to the end edge 211 of the electrode, and as a result, damage to the end edge 211 of the electrode can be suitably suppressed.

[0050] Also, by way of example, the end edge 211 of the electrode can be positioned outboard of the inner edge 412 of the support frame 410, as shown in Figures 4A and 4C. Alternatively, the end edge 211 of the electrode can be positioned on the inner edge 412 of the support frame 410, as shown in Figure 4B.

[0051] Of the above embodiments, it is preferable to adopt an embodiment in which the end edge 211 of the electrode is positioned outside the inner edge 412 of the support frame 410. In an embodiment in which the end edge 211 of the electrode is positioned on the inner edge 412 of the support frame 410, it is conceivable that the end edge 211 of the electrode may fall into the electrode chamber during use.

[0052] In contrast, in an embodiment in which the end edge 211 of the electrode is positioned outboard of the inner edge 412 of the support frame 410, it is possible to preferably prevent the end edge 211 of the electrode from falling into the electrode chamber during use. In particular, if a structure is adopted in which there is no gap between the gasket 500 and the end edge 211 of the electrode, it is possible to preferably prevent the diaphragm 300 from being pushed outward due to such a gap.

[0053] Furthermore, in an embodiment in which the end edge 211 of the electrode is positioned outboard of the inner edge 412 of the support frame 410, electrodes of a relatively larger size can be used compared to an embodiment in which the end edge 211 of the electrode is positioned on the inner edge 412 of the support frame 410. This is expected to further improve the overall electrolysis function of the electrolytic cell 100 according to one embodiment of the present invention.

[0054] Moreover, it is preferable that the end 210 of the electrode is curved in cross-sectional view. As described above, since the electrode for electrolysis is often made of an expanded metal having a mesh, a porous or an opening, the end edge 211 of the electrode may become sharp. Specifically, the end edge 211 of the electrode 200 may become a sharp edge that is jagged due to a plurality of wires forming the holes or openings. Therefore, the sharp end edge 211 may damage the diaphragm.

[0055] In this regard, in the electrolytic cell 100 according to one embodiment of the present invention, as shown in Figs. 4A to 4C, when the end edge 211 of the electrode and the sealing surface 411 of the support frame are positioned to overlap, the end 210 of the electrode including the end edge 211 of the electrode is curved, so that the end 210 of the electrode can be oriented in a direction away from the diaphragm 300. From another perspective, when the end of the electrode is curved, the diaphragm 300 and the main part of the electrode are in close contact with each other, while the diaphragm 300 and the end 210 of the electrode other than the main part of the electrode are not in close contact with each other. In this specification, the "main part of the electrode" means a main region of the electrode excluding the end 210 of the electrode. In other words, the part from the starting point of the curvature to the edge of the electrode means the "end of the electrode other than the diaphragm and the main part of the electrode". As described above, the end edge 211 of the electrode and the diaphragm 300 can be prevented from coming into direct contact with each other, and as a result, damage to the diaphragm 300 can be preferably prevented.

[0056] The degree of curvature of the electrode end is not particularly limited as long as it can prevent contact between the sharp end edge 211 and the diaphragm 300. For example, the distance between the main part of the electrode (the part of the electrode excluding the end 210) and the end edge 211 of the electrode may be about 0.1 mm to 10 mm, preferably about 1 mm to 6 mm, and can be, for example, 4 mm.

[0057] As described above, the electrode overlapping the sealing surface 411 of the support frame 410 may be at least one of the anode and cathode. In this regard, the technical problem found by the present inventors (part of the diaphragm located on the electrode enters the gap, causing relatively large local deformation of the diaphragm) may occur due to the action of a force pressing the diaphragm toward the electrode by the conductive elastic body. In view of this, it is preferable that the electrode overlapping the sealing surface 411 of the support frame 410 is the electrode on the side against which the diaphragm 300 is pressed by the conductive elastic body. In addition, the technical problem found by the present inventors becomes prominent when the diaphragm contacts the end of the electrode on the rigid side, that is, relatively large local deformation (i.e. bending) is more likely to occur. In view of this, it is preferable that the electrode overlapping the sealing surface 411 of the support frame 410 is the electrode on the relatively rigid side.

[0058] Although one embodiment of the present invention has been described above, it is merely a typical example. Therefore, the present invention is not limited to this, and it will be easily understood by those skilled in the art that various embodiments are possible. [Industrial Applicability]

[0059] The technology based on the present invention can be used in various electrolytic cells in which electrolysis, i.e., electrolysis, is performed. For example, the present invention can be used in electrolytic cells used in the soda industry, and is particularly suitable for electrolytic cells in which damage to the diaphragm by the electrodes is a concern. [Explanation of symbols]

[0060] 100 electrolytic cell 100' Conventional Electrolyzer 200 Electrode for electrolysis 200A, 200A' cathode 200B, 200B' Anode 210 Electrode End 211 Electrode Edge 300, 300' diaphragm 400, 400' support 410 Support frame 411, 411' sealing surface of support frame 412, 412' inner edge of support frame 420 bottom 500, 500' gasket 510, 510' Inner edge of gasket 600 Ribs 700 Conductive elastic body 710 Fixed part 720 Elastic section / bi-elastic section 740 Mounting opening A Cathode chamber B Anode chamber

Claims

1. An electrolytic cell comprising an anode, a cathode, a diaphragm disposed between the anode and the cathode, a conductive elastomer, and a support frame, In a plan view, at least an end edge of at least one of the anode and cathode electrodes overlaps a sealing surface of the support frame; the conductive elastic body is provided on the rear surface side of the one electrode, and the one electrode is biased so as to be pressed toward the other electrode, thereby bringing about close contact between the one electrode, the diaphragm, and the other electrode, a gasket positioned on the sealing surface; the end edge being positioned on a sealing surface between an inner edge of the gasket and an inner edge of a sealing surface of the support frame.

2. 2. The electrolytic cell of claim 1, wherein the end edge is located at the sealing surface.

3. 3. An electrolytic cell according to claim 1 or 2, wherein the end edge is located at or outside the inner edge of the support frame.

4. 4. An electrolytic cell according to any preceding claim, wherein the end edge and the sealing surface are spaced apart from each other.

5. 5. The electrolytic cell according to claim 1, wherein in cross-section, the ends of the electrodes are curved.

6. 6. An electrolytic cell according to claim 1, wherein the inner edge of the gasket is located outside the inner edge of the sealing surface of the support frame.

7. 7. An electrolytic cell according to claim 1, wherein the size of the electrodes, in plan view, is greater than the size of the area enclosed by the inner edge of the support frame.

8. the diaphragm is in intimate contact with a main surface of the electrode other than a portion extending from a starting point of curvature of the electrode to an edge of the electrode, 6. The electrolytic cell according to claim 5, wherein the diaphragm is not in close contact with the portion of the electrode extending from the starting point of the curvature to the edge of the electrode.

9. 9. An electrolytic cell according to any preceding claim, wherein one of the anode and cathode electrodes is relatively rigid with respect to the other of the anode and cathode electrodes.

10. The electrolytic cell according to any one of claims 1 to 9, wherein the electrolytic cell is a zero-gap electrolytic cell.

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