Electrochemical cells and cell stacks

Abstract

To provide an electrochemical cell in which short circuits are reduced between an anode electrode plate and a cathode electrode plate.SOLUTION: An electrochemical cell 1 comprises: a diaphragm 11; an anode electrode plate 12 which contacts one surface of the diaphragm 11; and a cathode electrode plate 13, which contacts the other surface of the diaphragm 11, having a smaller mechanical strength than the anode electrode plate 12. The outer peripheral edge 12c of the anode electrode plate 12 is positioned outside of the outer peripheral edge 13c of the cathode electrode plate 13.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to electrochemical cells and cell stacks.

Background Art

[0002] An electrochemical cell includes, for example, a separator such as an electrolyte membrane, and an anode electrode plate and a cathode electrode plate arranged with the separator interposed therebetween. In such an electrochemical cell, a fluid composed of a liquid, a gas, or a mixture of a liquid and a gas is supplied to at least one of the anode electrode plate and the cathode electrode plate, and a potential difference is externally applied between the anode electrode plate and the cathode electrode plate to allow a current to flow therethrough. As a result, ionized substances pass through the separator and an electrochemical reaction occurs.

[0003] The above electrochemical cell is sometimes used for water electrolysis in which hydrogen (H2) is extracted from the cathode electrode plate side by supplying water (H2O) to the anode electrode plate side. The above electrochemical cell may also be used for carbon dioxide electrolysis in which carbon monoxide (CO) is extracted from the cathode electrode plate side by supplying water (H2O) containing a trace amount of electrolyte to the anode electrode plate side and supplying carbon dioxide (CO2) to the cathode electrode plate side.

[0004] In such an electrochemical cell, when a fluid (hereinafter referred to as an anode fluid) is supplied to the anode electrode plate side and a fluid (hereinafter referred to as a cathode fluid) is supplied to the cathode electrode plate side, a flow path plate that forms a flow path for allowing the anode fluid and the cathode fluid to flow therethrough is usually used.

[0005] Some channel plates have a channel-forming portion on one side for forming a channel for the anode fluid and a channel-forming portion on the other side for forming a channel for the cathode fluid. This channel plate forms an anode fluid channel between itself and the anode electrode plate by contacting it on one side, and a cathode fluid channel between itself and the cathode electrode plate by contacting it on the other side. Such channel plates are sometimes used when fabricating cell stacks with multiple electrochemical cells.

[0006] A cell stack can be fabricated by alternately stacking electrode plate units, each consisting of a diaphragm, an anode electrode plate, and a cathode electrode plate, with the aforementioned flow channel plates. In such a cell stack, the stack, which includes multiple electrode plate units and multiple flow channel plates, is usually fixed by tightening the stack from both ends in the stacking direction. When tightening is performed in this way, adjacent electrode plate units and flow channel plates are tightened in a direction that brings them closer to each other. In addition, within each electrode plate unit, a force is generated that brings the anode electrode plate and the cathode electrode plate closer to each other. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6672193 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the electrochemical cell described above, the material of the anode electrode plate may be the same as the material of the cathode electrode plate. Alternatively, the material of the anode electrode plate may be different from that of the cathode electrode plate. When the materials of the anode electrode plate and the cathode electrode plate are different, the anode electrode plate may be made of a porous material such as a mesh material, perforated material, porous body, or sintered metal fiber body made of titanium (Ti), nickel (Ni), iron (Fe), etc. The cathode electrode plate may be made of a porous carbon substrate such as carbon paper or carbon cloth.

[0009] Incidentally, when, for example, the tightening process described above during the fabrication of a cell stack generates a force that brings the anode electrode plate and the cathode electrode plate closer together, if the materials of the anode electrode plate and the cathode electrode plate are different, the electrode plate with higher mechanical strength, especially its outer periphery, will be more likely to penetrate the diaphragm than the electrode plate with lower mechanical strength. For example, if the anode electrode plate is made of a metal mesh and the cathode electrode plate is made of carbon paper, the anode electrode plate will be more likely to penetrate the diaphragm than the cathode electrode plate. If either or both of the anode electrode plate and the cathode electrode plate penetrate the diaphragm, a short circuit between the anode electrode plate and the cathode electrode plate may occur.

[0010] When both the anode and cathode electrode plates are made of materials with low mechanical strength, such as carbon paper, penetration of the electrode plate diaphragm has not been a major problem until now. However, when the materials of the anode and cathode electrode plates are different from each other, a situation may arise where one of the electrode plates is more likely to penetrate the diaphragm, as described above. Therefore, it is desirable to take measures to suppress short circuits caused by penetration of the electrode plate diaphragm.

[0011] Therefore, the problem that the present invention aims to solve is to provide an electrochemical cell and cell stack that can reduce short circuits between the anode electrode plate and the cathode electrode plate. [Means for solving the problem]

[0012] An electrochemical cell according to one embodiment comprises a diaphragm, a first electrode plate in contact with one surface of the diaphragm, and a second electrode plate in contact with the other surface of the diaphragm and having less mechanical strength than the first electrode plate. The outer edge of the first electrode plate is located outside the outer edge of the second electrode plate.

[0013] Furthermore, a cell stack according to one embodiment comprises the aforementioned plurality of electrochemical cells and a plurality of flow channel plates, wherein the electrochemical cells and the flow channel plates are stacked alternately. [Effects of the Invention]

[0014] According to the present invention, short circuits between the anode electrode plate and the cathode electrode plate can be reduced. [Brief explanation of the drawing]

[0015] [Figure 1] This is a plan view of an electrochemical cell according to one embodiment. [Figure 2] Figure 1 is a cross-sectional view of an electrochemical cell. [Figure 3] Figure 1 is a cross-sectional view of the electrode plates that make up the electrochemical cell. [Figure 4] Figure 1 is a cross-sectional view of a cell stack equipped with an electrochemical cell. [Figure 5] (A) and (B) are diagrams showing modified versions of the electrochemical cell in Figure 1. [Modes for carrying out the invention]

[0016] Hereinafter, an electrochemical cell 1 according to one embodiment will be described in detail with reference to the attached drawings. Note that the term "plate" as used herein is not distinguished from materials such as sheets, films, or foils based solely on differences in designation.

[0017] <Electrochemical cell> FIG. 1 is a plan view of an electrochemical cell 1 according to an embodiment. FIG. 2 is a cross-sectional view of the plate-shaped electrochemical cell 1 of FIG. 1 taken along the thickness direction thereof. The electrochemical cell 1 shown in FIG. 1 and FIG. 2 includes an electrode plate unit 10 and an electrode plate outer frame 20. The electrode plate outer frame 20 is arranged so as to surround the periphery of the electrode plate unit 10 and is integrated with the electrode plate unit 10.

[0018] The electrode plate unit 10 includes a diaphragm 11, an anode electrode plate 12 in contact with one surface of the diaphragm 11, and a cathode electrode plate 13 in contact with the other surface of the diaphragm 11. The diaphragm 11, the anode electrode plate 12, and the cathode electrode plate 13 are laminated in a state where their respective thickness directions are parallel to each other. The one surface and the other surface of the diaphragm 11 mean one surface in the thickness direction of the diaphragm 11 and the other surface opposite to the one surface. In the present embodiment, the anode electrode plate 12 corresponds to a first electrode plate, and the cathode electrode plate 13 corresponds to a second electrode plate.

[0019] The diaphragm 11 is an ion filtration membrane such as a solid polymer membrane (ion exchange membrane) or a solid electrolyte membrane (electrolyte membrane). For example, when water electrolysis is performed using the electrochemical cell 1, the anode electrode plate 12 is supplied with water (H2O) as an anode fluid. At this time, hydrogen (H2) is extracted from the cathode electrode plate 13 side.

[0020] As an example, the anode electrode plate 12 includes a metal base material (hereinafter referred to as anode base material) and an anode catalyst material adhered to or contained in the anode base material. The anode base material has a structure that allows the anode fluid and ions to move when the anode fluid is supplied thereto. The anode base material may include at least one selected from the group consisting of, for example, a metal mesh material, a metal punching material, a metal porous body, and a sintered metal fiber body. The metal mesh material, punching material, porous body, and sintered metal fiber body that can constitute the anode base material may be formed of a metal material such as a metal such as titanium (Ti), nickel (Ni), or iron (Fe), or an alloy containing at least one of these metals (e.g., SUS).

[0021] The anode catalyst material may be a metal such as platinum (Pt), palladium (Pd), or nickel (Ni), an alloy or intermetallic compound containing any of these metals, a binary metal oxide such as manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), ruthenium oxide (Ru-O), lithium oxide (Li-O), or lanthanum oxide (La-O), a ternary metal oxide such as Ni-Co-O, Ni-Fe-O, La-Co-O, Ni-La-O, or Sr-Fe-O, a quaternary metal oxide such as Pb-Ru-Ir-O or La-Sr-Co-O, or a metal complex such as a Ru complex or an Fe complex. Further, the anode catalyst material may be a nanoparticle, a nanostructure, or a nanowire. A nanostructure is a structure having nanoscale irregularities formed on the surface of the catalyst material.

[0022] As one example, the cathode electrode plate 13 includes a base material having a carbon material (hereinafter referred to as a cathode base material) and a cathode catalyst material formed on a surface of the cathode base material. The cathode base material may include at least one selected from the group consisting of carbon paper, carbon cloth, and a fired body of carbon powder and a resin material.

[0023] The cathode catalyst material is provided, for example, in the form of a film formed on a surface of the cathode base material, and in this case is in contact with the diaphragm 11. The cathode catalyst material may be a metal such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), or tin (Sn), a metal material such as an alloy or intermetallic compound containing at least one of these metals, a carbon material such as carbon (C), graphene, CNT (carbon nanotube), fullerene, or Ketjenblack, or a metal complex such as a Ru complex or a Re complex.

[0024] In this embodiment, the mechanical strength of the cathode electrode plate 13 is lower than that of the anode electrode plate 12. Specifically, in this embodiment, the anode substrate of the anode electrode plate 12 has a titanium metal fiber sintered body, and the cathode substrate of the cathode electrode plate 13 is made of carbon paper and is a thin sheet. As a result, the mechanical strength of the cathode electrode plate 13 is lower than that of the anode electrode plate 12. More specifically, in this embodiment, at least the Vicker vinegar The hardness of the anode electrode plate 12 is determined by the Vicker vinegar It's smaller than hardness.

[0025] As will be described in detail later, the electrochemical cell 1 is stacked alternately with, for example, a flow channel plate 111 (see Figure 4) to form a cell stack 100. In this case, the stack, which includes multiple electrochemical cells 1 and multiple flow channel plates 111, is fixed by being clamped from both sides in the stacking direction. During such clamping, the anode electrode plate 12 and the cathode electrode plate 13 receive a large clamping force in the direction of proximity to each other, particularly at their outer periphery. At this time, as mentioned above, if the mechanical strength of the cathode electrode plate 13 is less than the mechanical strength of the anode electrode plate 12, the anode electrode plate 12 is more likely to penetrate the diaphragm 11 and come into contact with the cathode electrode plate 13.

[0026] Furthermore, in this embodiment, the anode electrode plate 12 contains metal, and relatively hard and sharp burrs may form on its outer circumference, resulting in a rough surface. This can make it easier for the outer circumference of the anode electrode plate 12 to penetrate the diaphragm 11. Moreover, due to the warping of the clamping member, stress tends to concentrate more on the outer circumference of the anode electrode plate 12 than on the central side, and as a result, the outer circumference of the anode electrode plate 12 becomes more likely to penetrate the diaphragm 11.

[0027] Therefore, the electrochemical cell 1 is configured such that the outer edge 12c of the anode electrode plate 12 is located outside the outer edge 13c of the cathode electrode plate 13, as shown in Figure 2. This reduces the likelihood of a short circuit between the anode electrode plate 12 and the cathode electrode plate 13, even if the outer edge of the anode electrode plate 12 penetrates the diaphragm 11.

[0028] More specifically, the anode electrode plate 12 and the cathode electrode plate 13 are rectangular in shape when viewed from above, or in other words, in the thickness direction, as shown in Figure 1. The edges of the anode electrode plate 12 and the cathode electrode plate 13 are aligned, and the anode electrode plate 12 overlaps with the cathode electrode plate 13, encompassing its entirety. That is, the outer edge 12c of the anode electrode plate 12 is located outside the outer edge 13c of the cathode electrode plate 13 over its entire surface. As a result, in this embodiment, the electrochemical cell 1 can reduce short circuits between the anode electrode plate 12 and the cathode electrode plate 13 even if the outer edge of the anode electrode plate 12 penetrates the diaphragm 11 over a wide area or entirely. However, a configuration in which the outer edge 12c of the anode electrode plate 12 is partially located outside the outer edge 13c of the cathode electrode plate 13 may also be adopted.

[0029] Furthermore, in this embodiment, the diaphragm 11 is larger than the anode electrode plate 12, and the outer edge 11c of the diaphragm 11 is located outside the outer edge 12c of the anode electrode plate 12. Specifically, as shown in Figure 1, the diaphragm 11 is rectangular in plan view, or in other words, in the thickness direction, and when it is superimposed with the anode electrode plate 12 and cathode electrode plate 13 with their edges aligned, it encloses the entire anode electrode plate 12 and cathode electrode plate 13. As a result, the outer edge 11c of the diaphragm 11 is located outside the outer edge 12c of the anode electrode plate 12 throughout its entire surface.

[0030] In this embodiment, the portion of the diaphragm 11 located outside the outer peripheral edge 12c of the anode electrode plate 12 (the outer peripheral portion) is covered by the electrode plate outer frame 20. More specifically, the electrode plate outer frame 20 covers and holds the outer peripheral portion of the diaphragm 11 from both sides in the thickness direction.

[0031] More specifically, the electrode plate outer frame 20 includes an anode outer frame member 21 positioned outside the outer peripheral edge 12c of the anode electrode plate 12, and a cathode outer frame member 22 positioned outside the outer peripheral edge 13c of the cathode electrode plate 13 and facing the anode outer frame member 21. The outer peripheral portion of the diaphragm 11 is sandwiched and held between these anode outer frame member 21 and cathode outer frame member 22. In this embodiment, the anode outer frame member 21 corresponds to the first electrode outer frame member, and the cathode outer frame member 22 corresponds to the second electrode outer frame member.

[0032] The anode outer frame member 21 is a plate material having a rectangular opening. The anode electrode plate 12 is housed in the anode outer frame member 21 by fitting it into the opening. The cathode outer frame member 22 is also a plate with a rectangular opening. The cathode electrode plate 13 is housed in the cathode outer frame member 22 by fitting it into the opening. Here, the cathode outer frame member 22 includes a support portion 22S that faces the portion of the anode electrode plate 12 that is located outside the outer peripheral edge 13c of the cathode electrode plate 13.

[0033] The opening of the cathode outer frame member 22 is slightly smaller than the opening of the anode outer frame member 21. When the cathode outer frame member 22 and the anode outer frame member 21 are positioned facing each other, the peripheral edge of the opening of the cathode outer frame member 22 is exposed from the opening of the anode outer frame member 21. The support portion 22S described above is formed on this exposed portion. The support portion 22S is the part that supports the anode electrode plate 12 via the outer peripheral portion of the diaphragm 11 when the anode electrode plate 12 is pressed against the diaphragm 11.

[0034] Furthermore, in this embodiment, the anode outer frame member 21 and the cathode outer frame member 22 sandwich the outer periphery of the diaphragm 11 via an adhesive layer 24. The adhesive layer 24 is insulating. The adhesive layer 24 may be organic or inorganic. The adhesive layer 24 may be formed by curing an adhesive, or it may be made of a volatile adhesive, or it may be made of a pressure-sensitive adhesive such as adhesive tape.

[0035] The adhesive layer 24 is interposed between the anode outer frame member 21 and the cathode outer frame member 22, joining the anode outer frame member 21 and the cathode outer frame member 22. The outer periphery of the diaphragm 11 is embedded inside the adhesive layer 24 between the anode outer frame member 21 and the cathode outer frame member 22. This creates a state in which the anode outer frame member 21 and the cathode outer frame member 22 sandwich the outer periphery of the diaphragm 11 via the adhesive layer 24. The thickness of the adhesive layer 24 is not particularly limited, but it is greater than the thickness of the diaphragm 11.

[0036] When assembling the electrochemical cell 1, for example, the anode electrode plate 12 is incorporated into the anode outer frame member 21, and adhesive is applied to the surface of the anode outer frame member 21 facing the cathode outer frame member 22. Also, the cathode electrode plate 13 is incorporated into the cathode outer frame member 22, and adhesive is applied to the surface of the cathode outer frame member 22 facing the anode outer frame member 21. Then, for example, a diaphragm 11 is placed on top of the cathode electrode plate 13 and the adhesive on the cathode outer frame member 22. Subsequently, the anode outer frame member 21 and anode electrode plate 12 are placed on top of the cathode outer frame member 22 and cathode electrode plate 13, so that the adhesive on the anode outer frame member 21 is in contact with the adhesive on the cathode outer frame member 22 and the anode electrode plate 12 is in contact with the diaphragm 11. As a result, a part of the diaphragm 11 penetrates into the adhesive layer 24.

[0037] Furthermore, as shown in Figure 1, the outer frame 20 of the electrode plate is provided with an anode fluid inlet communication hole 26A, an anode fluid outlet communication hole 26B, a cathode fluid inlet communication hole 27A, and a cathode fluid outlet communication hole 27B. The anode fluid inlet communication hole 26A is a hole through which the anode fluid supplied onto the anode electrode plate 12 passes. The anode fluid outlet communication hole 26B is a hole through which the anode fluid flowing out from the anode electrode plate 12 passes. The cathode fluid inlet communication hole 27A is a hole through which the cathode fluid supplied onto the cathode electrode plate 13 passes. The cathode fluid outlet communication hole 27B is a hole through which the cathode fluid flowing out from the cathode electrode plate 13 passes.

[0038] The electrode plate outer frame 20 may be made of resin materials such as fluororesin, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or polyethylene naphthalate (PEN). The electrode plate outer frame 20 may also be made of an electrically insulating material such as rubber material such as fluororubber or ethylene propylene diene rubber (EPDM). The electrode plate outer frame 20 may also be constructed by installing an electrically insulating material in the area of ​​the surface of a conductive substrate that comes into contact with the fluid.

[0039] <Cell Stack> The following describes an example of a cell stack 100 equipped with an electrochemical cell 1. The cell stack 100 shown in Figure 4 comprises a plurality of electrochemical cells 1, a plurality of flow channel plate assemblies 110, a first clamping plate 121, and a second clamping plate 122.

[0040] The flow channel plate assembly 110 includes a flow channel plate 111 and a flow channel plate outer frame 112 that is integrated with the flow channel plate 111, surrounding its outer peripheral edge. The flow channel plate assembly 110 is arranged such that the flow channel plate 111 overlaps the electrode plate unit 10 and the flow channel plate outer frame 112 overlaps the electrode plate outer frame 20. In the illustrated example, the flow channel plate 111 is corrugated and has an anode flow channel groove 111a on one surface (the lower surface in Figure 4) and a cathode flow channel groove 111c on the other surface (the upper surface in Figure 4). When the flow channel plate 111 contacts the anode electrode plate 12 at the anode flow channel groove 111a, it forms an anode fluid flow channel together with the anode electrode plate 12. When the flow channel plate 111 contacts the cathode electrode plate 13 at the cathode flow channel groove 111c, it forms a cathode fluid flow channel together with the cathode electrode plate 13.

[0041] In the cell stack 100, multiple electrochemical cells 1 and multiple flow channel plate assemblies 110 are stacked alternately. This creates a state in which multiple electrochemical cells 1, specifically their electrode plate units 10 and multiple flow channel plates 111, are stacked alternately. In this stacked state, in the illustrated example, the outer periphery of the electrode plate unit 10 overlaps with each of the flow channel plate outer frames 112 of the flow channel plate assemblies 110 that are arranged on both sides of the electrode plate unit 10 in the thickness direction. The outer periphery of the electrode plate unit 10 that overlaps as if sandwiched between the two flow channel plate outer frames 112 includes the outer periphery of the diaphragm 11, the outer periphery of the anode electrode plate 12, and the outer periphery of the cathode electrode plate 13. However, part or all of the outer periphery of the electrode plate unit 10 does not have to overlap with the flow channel plate outer frames 112 in the thickness direction.

[0042] Furthermore, the first clamping plate 121 is positioned to contact the flow channel plate assembly 110 located at one end in the stacking direction of the laminate, which includes the electrochemical cell 1 and the flow channel plate assembly 110, via the first current collector plate 131. The second clamping plate 122 is positioned to contact the flow channel plate assembly 110 located at the other end in the stacking direction via the second current collector plate 132. The first clamping plate 121 and the second clamping plate 122 are then clamped together by the fastening member 123 in a direction toward each other. This fixes the stacked electrochemical cell 1 and the flow channel plate assembly 110 in place. In this embodiment, the outer periphery of the electrode plate unit 10, which overlaps and is sandwiched between two flow channel plate outer frames 112, includes the outer periphery of the diaphragm 11, the outer periphery of the anode electrode plate 12, and the outer periphery of the cathode electrode plate 13. Therefore, when the above tightening is performed, the force that brings the outer periphery of the anode electrode plate 12 and the outer periphery of the cathode electrode plate 13 closer together is mainly transmitted from the flow channel plate outer frame 112.

[0043] Although not shown in the diagram, the outer frame 112 of the flow channel plate has a flow channel that connects the anode fluid inlet communication hole 26A and the anode fluid outlet communication hole 26B to the anode flow channel groove 111a in the flow channel plate 111. In addition, the outer frame 112 of the flow channel plate has a flow channel that connects the cathode fluid inlet communication hole 27A and the cathode fluid outlet communication hole 27B to the cathode flow channel groove 111c in the flow channel plate 111.

[0044] The flow channel plate 111 may be made of a conductive material such as carbon, a mixture of carbon and resin, or a conductive material with a conductive plating or coating applied to its surface. Plating or coating is applied to increase the corrosion potential or reduce contact resistance.

[0045] The flow channel plate outer frame 112 may be made of resin materials such as fluororesin, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or polyethylene naphthalate (PEN). Alternatively, the flow channel plate outer frame 112 may be made of an electrically insulating material such as rubber material such as fluororubber or ethylene propylene diene rubber (EPDM). Furthermore, the flow channel plate outer frame 112 may be constructed by installing an electrically insulating material on the surface of a conductive substrate in the area that comes into contact with the fluid.

[0046] As described above, the electrochemical cell 1 according to this embodiment comprises a diaphragm 11, an anode electrode plate 12 in contact with one surface of the diaphragm 11, and a cathode electrode plate 13 in contact with the other surface of the diaphragm 11 and having lower mechanical strength than the anode electrode plate 12. The outer peripheral edge 12c of the anode electrode plate 12 is located outside the outer peripheral edge 13c of the cathode electrode plate 13. This reduces the risk of short circuits between the anode electrode plate 12 and the cathode electrode plate 13.

[0047] In other words, for example, when the electrochemical cell 1 is incorporated into the cell stack 100 as described above, adjacent flow channel plates 111 and electrode plate units 10 are fixed in a state where they are tightened in a direction that brings them closer to each other. Such tightening generates a force that brings the anode electrode plate 12 and the cathode electrode plate 13 closer to each other. When such a force is generated, if the materials of the anode electrode plate 12 and the cathode electrode plate 13 are different, the outer periphery of the electrode plate with higher mechanical strength (in this embodiment, the anode electrode plate 12) is more likely to penetrate the diaphragm 11. Therefore, the risk of a short circuit between the anode electrode plate 12 and the cathode electrode plate 13 increases. Here, in this embodiment, the outer periphery 12c of the anode electrode plate 12 is located outside the outer periphery 13c of the cathode electrode plate 13. As a result, even if the outer periphery of the anode electrode plate 12 penetrates the diaphragm 11, there is no cathode electrode plate 13 beyond the penetration point, thus preventing contact between the anode electrode plate 12 and the cathode electrode plate 13. Therefore, short circuits between the anode electrode plate 12 and the cathode electrode plate 13 can be reduced.

[0048] <Variation> Next, a modified example of the above-described embodiment will be explained with reference to Figure 5. In the above-described embodiment, the anode outer frame member 21 and the cathode outer frame member 22 sandwich the portion of the diaphragm 11 located outside the outer peripheral edge 12c of the anode electrode plate 12 via the adhesive layer 24. In the modified example shown in Figure 5, the adhesive layer 24 is not interposed between the diaphragm 11 and the electrode plate outer frame 20.

[0049] First, in Figure 5(A), the electrode plate outer frame 20 is not separated into two parts. On the other hand, the electrode plate outer frame 20 has an opening 20a for the anode electrode and a cathode electrode opening 20c which is smaller than the anode electrode opening 20a. A stepped portion 20S is formed in the electrode plate outer frame 20 between the anode electrode opening 20a and the cathode electrode opening 20c. The stepped portion 20S forms a support portion 22S. The diaphragm 11 and the anode electrode plate 12 are stacked on the stepped portion 20S in this order. Even with this configuration, even if the outer circumference of the anode electrode plate 12 penetrates the diaphragm 11, there is no cathode electrode plate 13 beyond the penetration point, so contact between the anode electrode plate 12 and the cathode electrode plate 13 can be avoided. Therefore, short circuits between the anode electrode plate 12 and the cathode electrode plate 13 can be reduced.

[0050] Furthermore, in Figure 5(B), the electrode plate outer frame 20 comprises an anode outer frame member 21 and a cathode outer frame member 22, but no adhesive layer 24 is provided between the anode outer frame member 21 and the cathode outer frame member 22 and the diaphragm 11. Even with this configuration, short circuits between the anode electrode plate 12 and the cathode electrode plate 13 can be reduced.

[0051] Although one embodiment has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above-described embodiment and other variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

[0052] For example, in the above embodiment, a flow channel plate outer frame 112 is provided on the outer circumference of the flow channel plate 111, but it is also possible to have a configuration in which there is no flow channel plate outer frame 112, and the outer circumference of the flow channel plate 111 overlaps with the electrode plate outer frame 20.

[0053] Furthermore, in the above-described embodiment, an example was explained in which the anode substrate of the anode electrode plate 12 is a titanium metal fiber sintered body, and the cathode substrate of the cathode electrode plate 13 is carbon paper, resulting in the mechanical strength of the cathode electrode plate 13 being lower than that of the anode electrode plate 12. However, such material combinations are not particularly limited. Also, the mechanical strength of the anode electrode plate 12 may be lower than that of the cathode electrode plate 13.

[0054] Furthermore, for example, if the thickness of the anode electrode plate 12 is greater than the thickness of the cathode electrode plate 13, the mechanical strength of the anode electrode plate 12 may be greater than that of the cathode electrode plate 13. In this case, the materials of the anode electrode plate 12 and the cathode electrode plate 13 may be the same or different. For example, if the anode electrode plate 12 is made of a 1 mm thick platinum plate (Pt) and the cathode electrode plate 13 is made of a 0.1 mm thick platinum foil, the anode electrode plate 12 will be more likely to penetrate the diaphragm 11 than the cathode electrode plate 13. In this case, by positioning the outer edge 12c of the anode electrode plate 12 outside the outer edge 13c of the cathode electrode plate 13, it is possible to suppress short circuits. From the above viewpoint, positioning the outer edge of the electrode plate with greater bending rigidity (in terms of mechanical strength) outside the outer edge of the electrode plate with less bending rigidity (in terms of mechanical strength) of the anode electrode plate 12 and the cathode electrode plate 13 is effective in reducing short circuits. [Explanation of symbols]

[0055] 1…Electrochemical cell, 10…Electrode plate unit, 11…Diaphragm, 11c…Outer edge, 12…Anode electrode plate, 12c…Outer edge, 13…Cathode electrode plate, 13c…Outer edge, 20…Electrode plate outer frame, 20a…Opening for anode electrode, 20c…Opening for cathode electrode, 21…Outer frame member for anode, 22…Outer frame member for cathode, 22S…Support part, 24…Adhesive layer, 26A…Anode fluid inlet communication hole, 26B…Anode fluid outlet communication hole, 27A…Cathode fluid inlet communication hole, 27B…Cathode fluid outlet communication hole, 100…Cell stack, 110…Flow channel plate assembly, 111…Flow channel plate, 111a…Groove for anode flow channel, 111c…Groove for cathode flow channel, 112…Flow channel plate outer frame, 121…First clamping plate, 122…Second clamping plate

Claims

1. Diaphragm and, A first electrode plate in contact with one surface of the diaphragm, A second electrode plate, which is in contact with the other surface of the diaphragm and has a lower Vickers hardness than the first electrode plate, A first electrode outer frame member is positioned outside the outer peripheral edge of the first electrode plate, The second electrode outer frame member is positioned outside the outer peripheral edge of the second electrode plate and faces the first electrode outer frame member, and includes a support portion that faces the portion of the first electrode plate located outside the outer peripheral edge of the second electrode plate, Equipped with, The outer edge of the first electrode plate is located outside the outer edge of the second electrode plate throughout its entire area. The outer edge of the diaphragm is located outside the outer edge of the first electrode plate. The outer frame member for the first electrode and the outer frame member for the second electrode are provided with a communication hole for allowing fluid to pass through. Electrochemical cell.

2. The electrochemical cell according to claim 1, wherein the portion of the diaphragm located outside the outer peripheral edge of the first electrode plate is sandwiched between the first electrode outer frame member and the second electrode outer frame member.

3. The electrochemical cell according to claim 2, wherein the outer frame member for the first electrode and the outer frame member for the second electrode sandwich the portion of the diaphragm located outside the outer peripheral edge of the first electrode plate via an adhesive layer.

4. The electrochemical cell according to claim 3, wherein the adhesive layer joins the outer frame member for the first electrode and the outer frame member for the second electrode, and the portion of the diaphragm located outside the outer peripheral edge of the first electrode plate is embedded inside the adhesive layer between the outer frame member for the first electrode and the outer frame member for the second electrode.

5. The electrochemical cell according to any one of claims 1 to 4, wherein the first electrode plate includes a substrate having at least one selected from the group consisting of a metal mesh material, a metal punching material, a metal porous material, and a metal fiber sintered body.

6. The electrochemical cell according to any one of claims 1 to 4, wherein the second electrode plate includes a substrate having a carbon material.

7. The electrochemical cell according to claim 6, wherein the substrate of the second electrode plate has at least one selected from the group consisting of carbon paper, carbon cloth, and a fired body of carbon powder and resin material.

8. A plurality of electrochemical cells according to claim 1, It comprises multiple flow path plates, A cell stack comprising the electrochemical cells and the flow channel plates stacked alternately.

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