Electrochemical cell stack

Abstract

To provide an electrochemical cell stack capable of electrically insulating between a metal plate and a metal pipe.SOLUTION: An electrochemical cell stack according to an embodiment of the present invention includes a stacked body, an insulating plate, a metal plate, a metal pipe, and an insulating joint. The stacked body stacks an electrochemical cell including an electrode plate and a flow path plate stacked on the electrode plate, the flow path plate including an anode flow path that is disposed to face an anode electrode and through which an anode fluid flows, and a cathode flow path that is disposed to face a cathode electrode and through which a cathode fluid flows. The metal pipe communicates with the communication hole of the stacked body through which any one of the anode fluid and the cathode fluid flows into or flows out from the electrochemical cell, the first hole portion of the insulating plate, and the second hole portion of the metal plate. The insulating plate is an electrically insulating material disposed on the upper surface and the lower surface of the stacked body. The metal plate sandwiches the outside of the insulating plate. The metal pipe and the metal plate are insulated from each other by the insulating joint.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to electrochemical cell stacks. [Background technology]

[0002] Electrochemical cells consist of an anode electrode and a cathode electrode, which are arranged across a membrane such as an electrolyte membrane. A fluid consisting of a liquid, a gas, or a mixture of a liquid and a gas (hereinafter referred to as the anode fluid, cathode fluid, etc.) is supplied to at least one of the electrodes. An external potential difference is applied between the anode and cathode electrodes, allowing a current to flow. This causes ionized substances to pass through the membrane, resulting in an electrochemical reaction. For example, electrochemical cells are used in water electrolysis, in which water (HO) is supplied to the anode side and hydrogen (H) is extracted from the cathode outlet, or carbon dioxide electrolysis, in which water (HO) is supplied to the anode side and carbon dioxide (CO) is supplied to the cathode side and carbon monoxide (CO) is extracted from the cathode outlet. To promote the electrochemical reaction, electrolyte solutions containing small amounts of ionic substances dissolved in the liquid required for the reaction may also be used as the anode fluid or cathode fluid.

[0003] To supply the anode and cathode electrodes with anode fluid and cathode fluid, respectively, flow path plates are installed adjacent to the anode and cathode electrodes. The flow path plates have flow paths for the anode and cathode fluids to flow through. Furthermore, the flow path plates are made of a conductive material so that the electrodes are connected in series when multiple electrode plates and flow path plates are stacked.

[0004] To ensure uniform adhesion between the electrochemical cells and to enable the sealing material to function, both ends of the stacked cells are generally sandwiched between highly rigid members such as metal plates. Also, to prevent the current supplied from the power source from flowing through the metal plates to the ground, a plate-shaped part made of an electrically insulating material is sandwiched between the cell reaction section and the metal plate to prevent contact.

[0005] The metal plate has holes for passing the anode fluid and cathode fluid, and by attaching metal pipes, the fluids are passed through the communicating holes of the electrochemical cell. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Application No. 2022-121001 [Patent Document 2] Japanese Patent Application Publication No. 2023-85988 Summary of the Invention [Problem to be solved by the invention]

[0007] Furthermore, as electrochemical cell stacks become larger, the metal piping must be made of a highly rigid material to withstand the internal pressure of the fluid. However, if a metal is used as a highly rigid material for the metal piping, the metal piping and the fluid will have the same potential, which may necessitate electrical insulation between the metal piping and the metal plate.

[0008] The embodiments of the present invention have been made in consideration of the above circumstances, and provide an electrochemical cell stack that can provide electrical insulation between the metal plates and the metal piping. [Means for solving the problem]

[0009] An electrochemical cell stack according to an embodiment of the present invention includes a stack of electrochemical cells, each of which includes an electrode plate having a diaphragm, an anode electrode disposed on one main surface of the diaphragm, and a cathode electrode disposed on the other main surface of the diaphragm; and a flow path plate, stacked on the electrode plate, which is disposed opposite the anode electrode and has an anode flow path through which an anode fluid flows, and a cathode flow path disposed opposite the cathode electrode and through which a cathode fluid flows. The metal piping communicates with the communication holes of the stack, through which either the anode fluid or the cathode fluid flows into or out of the electrochemical cell, via a first hole in the insulating plate and a second hole in the metal plate. The insulating plates are made of electrically insulating material and are disposed on the upper and lower surfaces of the stack. The metal plates sandwich the outside of the insulating plates. The insulating joints insulate the metal piping from the metal plates. [Effects of the Invention]

[0010] According to the present invention, electrical insulation between a metal plate and a metal pipe is possible. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of an electrochemical cell stack according to an embodiment of the present invention. [Figure 2] 1A and 1B are front and side views of an electrochemical cell stack. [Figure 3] 1 is a perspective view of an electrochemical cell according to an embodiment of the present invention; [Figure 4] Cross-sectional view of line CC in Figure 3. [Figure 5] FIG. 2 is an exploded perspective view of an electrode plate and an electrode plate outer frame according to the embodiment. [Figure 6] FIG. 2 is a plan view of an electrode plate and an outer frame of the electrode plate according to the present embodiment. [Figure 7] A view of the electrode plate and outer frame of Figure 6 from the back. [Figure 8] Cross-sectional view of line DD in Figure 6. [Figure 9] FIG. 2 is an exploded perspective view of a flow path plate and a flow path plate outer frame according to the embodiment. [Figure 10] FIG. 3 is a plan view of a flow path plate and a flow path plate outer frame according to the present embodiment. [Figure 11] 11 is a view of the flow path plate and flow path plate outer frame in FIG. 10 as seen from the back side. [Figure 12] Cross section of line EE in Figure 10. [Figure 13] FIG. 1 shows a stack of electrochemical cells. [Figure 14] Cross section of line AA in Figure 2. [Figure 15] Cross-sectional view of line BB in Figure 2. [Figure 16] FIG. 3 corresponds to the cross-sectional view taken along line AA in FIG. 2. [Figure 17] FIG. 3 is a cross-sectional view corresponding to the line BB in FIG. 2. [Figure 18] FIG. 10 is a perspective view of an electrochemical cell stack according to a comparative example. [Figure 19] 3 is a cross-sectional view taken along line BB in FIG. 2 showing an example of an insulating joint that does not have a convex portion. [Figure 20] 3 is a cross-sectional view taken along line BB in FIG. 2 showing an example of an insulating joint having a shorter convex portion. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, electrochemical cell stacks according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are examples of embodiments of the present invention, and the present invention should not be construed as being limited to these embodiments. Furthermore, in the drawings referred to in this embodiment, identical parts or parts having similar functions are given the same or similar reference numerals, and repeated explanations thereof may be omitted. Furthermore, part of the configuration may be omitted from the drawings.

[0013] (First embodiment) First, with reference to FIGS. 1 to 13, examples of the configuration of an electrochemical cell stack and an electrochemical cell according to this embodiment will be described.

[0014] [Electrochemical cell stack configuration] Fig. 1 is a perspective view of an electrochemical cell stack 1 according to this embodiment. Fig. 2 is a front view and a side view of the electrochemical cell stack 1. As shown in Figs. 1 and 2, the electrochemical cell stack 1 according to this embodiment includes a plurality of electrochemical cells 2 stacked on top of each other. That is, the electrochemical cell stack 1 is configured by stacking a plurality of electrochemical cells 2.

[0015] 1 and 2, the electrochemical cell stack 1 includes an insulating plate 3 and a metal plate 4. The insulating plate 3 is a plate-shaped insulator made of an electrically insulating material. The insulating plates 3 are disposed on both ends of the stacked electrochemical cells 2 in the stacking direction.

[0016] The metal plate 4 is a plate-shaped conductor. The metal plate 4 is disposed on the upper end surface of the upper insulating plate 3 and on the lower end surface of the lower insulating plate 3. In other words, the metal plate 4 is disposed so as to sandwich the insulating plate 3. The metal plate 4 may be embedded in each insulating plate 3. The metal plate 4 is at, for example, a ground potential.

[0017] The metal plate 4 has a terminal 4a extending outward. An insulating bushing 4b is provided between the metal plate 4 and the terminal 4a. The terminal 4a is electrically connected to an external power source via a cable or the like. This allows a voltage to be applied from the external power source to each electrochemical cell 2, causing a current to flow.

[0018] The upper surface of the upper metal plate 4 and the lower surface of the lower metal plate 4 are fixed by tie rods 6. Clamping plates may be formed on the upper surface of the upper metal plate 4 and the lower surface of the lower metal plate 4. The clamping force of the tie rods 6 clamps the electrochemical cells 2 in a direction that brings them closer to each other.

[0019] As shown in FIG. 1, the electrochemical cell stack 1 further includes an insulating joint 7 and metal pipes 22a, 23b, 24c, and 25d. A first hole is provided in the insulating plate 3. A second hole, having an inner diameter larger than that of the first hole, is provided in the metal plate 4, corresponding to the first hole. The first and second holes are provided, and the metal pipes are attached to them, resulting in a structure in which fluids flow toward the communication holes of the electrochemical cells. Specifically, the metal plate 4 is fitted with an anode fluid inlet metal pipe 22a, an anode fluid outlet metal pipe 23b, a cathode fluid inlet metal pipe 24c, and a cathode fluid outlet metal pipe 25d.

[0020] 1 , the metal plate 4 has an anode fluid inlet metal pipe 22a, an anode fluid outlet metal pipe 23b, a cathode fluid inlet metal pipe 24c, and a cathode fluid outlet metal pipe 25d. These metal pipes 22a, 23b, 24c, and 25d are arranged on the metal plate 4 via insulating joints 7. The anode fluid inlet metal pipe 22a is connected to anode fluid inlet manifolds 12 and 22 of the electrochemical cell 2, which will be described later. The anode fluid outlet metal pipe 23b is connected to anode fluid outlet manifolds 13 and 23 of the electrochemical cell 2, which will be described later. The cathode fluid inlet metal pipe 24c is connected to cathode fluid inlet manifolds 14 and 24 of the electrochemical cell 2, which will be described later. The cathode fluid outlet metal pipe 25d is connected to cathode fluid outlet manifolds 15 and 25 of the electrochemical cell 2, which will be described later. Anode fluid supplied from the outside flows into the anode fluid inlet metal pipe 22a. After the electrochemical reaction in each electrochemical cell 2, the anode fluid flows out to the outside through the anode fluid outlet metal pipe 23b. Cathode fluid supplied from the outside flows into the cathode fluid inlet metal pipe 24c. After the electrochemical reaction in each electrochemical cell 2, the cathode fluid flows out to the outside through the cathode fluid outlet metal pipe 25d. Note that detailed configuration examples of the cross sections of the insulating joint 7 and the metal pipes 22a, 23b, 24c, and 25d taken along lines AA and BB (see FIG. 2) will be described later using FIGS. 14 and 15.

[0021] [Electrochemical cell configuration]

[0022] Fig. 3 is a perspective view of an electrochemical cell 2 according to this embodiment. Fig. 4 is a cross-sectional view taken along line CC in Fig. 3. As shown in Figs. 3 and 4, the electrochemical cell 2 according to this embodiment includes an electrode plate 10 and an electrode plate outer frame 11, and a flow path plate 20 and a flow path plate outer frame 21. The electrochemical cell 2 has a structure in which the electrode plate 10 and the electrode plate outer frame 11, and the flow path plate 20 and the flow path plate outer frame 21 are stacked as a set.

[0023] Fig. 5 is an exploded perspective view of the electrode plate 10 and the electrode plate outer frame 11 according to the present embodiment. Fig. 6 is a plan view of the electrode plate 10 and the electrode plate outer frame 11 according to the present embodiment. Fig. 7 is a view of the electrode plate 10 and the electrode plate outer frame 11 of Fig. 6 as seen from the back side. Fig. 8 is a cross-sectional view taken along line DD in Fig. 6.

[0024] As shown in Fig. 5, the electrode plate 10 according to this embodiment has a diaphragm 16, an anode electrode 17, and a cathode electrode 18. The anode electrode 17 and the cathode electrode 18 are arranged with the diaphragm 16 sandwiched between them. That is, the anode electrode 17 and the cathode electrode 18 are arranged on either side of the diaphragm 16. The anode electrode 17 is arranged on one main surface of the diaphragm 16 (the upper side in Figs. 5 and 8), and the cathode electrode 18 is arranged on the other main surface of the diaphragm 16 (the lower side in Figs. 5 and 8).

[0025] The diaphragm 16 may be an ion filtration membrane such as a solid polymer membrane (ion exchange membrane) or a solid electrolyte membrane (electrolyte membrane). The anode electrode 17 and the cathode electrode 18 may be configured by attaching a catalyst containing a metal such as nickel, iridium, gold, silver, or platinum, or a metal oxide such as nickel oxide, iridium dioxide, or cobalt oxide to a gas-permeable substrate made of carbon or metal.

[0026] As shown in Fig. 5, the diaphragm 16, the anode electrode 17, and the cathode electrode 18 may each be formed in a flat plate shape. As shown in Fig. 5, the cathode electrode 18 may have the same planar size as the diaphragm 16. On the other hand, the anode electrode 17 may have a planar size smaller than that of the diaphragm 16. This may result in a step being formed between the anode electrode 17 and the diaphragm 16, as shown in Figs. 5 and 8.

[0027] As shown in FIGS. 5 to 8, an electrode plate outer frame 11 is disposed on the outside of the electrode plate 10. The electrode plate outer frame 11 is joined to the electrode plate 10. The electrode plate outer frame 11 may be joined to the outer periphery of the electrode plate 10. Alternatively, as shown in FIGS. 5 and 8, the electrode plate outer frames 11 may be overlapped and joined in the stacking direction so as to cover the step between the anode 17 of the electrode plate 10 and the diaphragm 16. In this case, the joining area of ​​the joining portion between the electrode plate 10 and the electrode plate outer frame 11 can be increased, and the sealing performance at the joining portion can be improved.

[0028] 5 to 8, the electrode plate outer frame 11 has an anode fluid inlet communication hole 12, an anode fluid outlet communication hole 13, a cathode fluid inlet communication hole 14, and a cathode fluid outlet communication hole 15. These communication holes 12, 13, 14, and 15 are each provided at a distance from the electrode plate 10. These communication holes 12, 13, 14, and 15 each penetrate the electrode plate outer frame 11 in the thickness direction (stacking direction).

[0029] 5 and 6, the electrode plate outer frame 11 has anode communication grooves 19a and 19b. The anode communication groove 19a connects the anode fluid inlet manifold 12 to an anode flow path 26 in the flow path plate 20, which will be described later. That is, the anode communication groove 19a allows the anode fluid to flow from the anode fluid inlet manifold 12 to the anode flow path 26 in the flow path plate 20. The anode communication groove 19b connects the anode flow path 26 in the flow path plate 20 to the anode fluid outlet manifold 13. That is, the anode communication groove 19b allows the anode fluid to flow from the anode flow path 26 in the flow path plate 20 to the anode fluid outlet manifold 13.

[0030] As shown in FIGS. 5 and 6, the anode connecting grooves 19a, 19b may include multiple grooves formed on the surface of the electrode plate outer frame 11. That is, the anode connecting grooves 19a, 19b may be composed of multiple grooves through which the anode fluid flows. Furthermore, as shown in FIGS. 5 and 6, the anode connecting grooves 19a, 19b may extend from the communication holes 12, 13. On the other hand, the anode connecting grooves 19a, 19b do not have to extend to the electrode plate 10. That is, the anode connecting grooves 19a, 19b may be spaced apart from the electrode plate 10. As shown in FIGS. 5 and 6, the anode connecting grooves 19a, 19b may be serpentine flow channels having multiple bends.

[0031] 5 and 6, the electrode plate outer frame 11 may have a laminated sealing member 30. The laminated sealing member 30 may be provided so as to surround the anode fluid inlet manifold 12, the anode connecting groove 19a, the electrode plate 10, the anode connecting groove 19b, and the anode fluid outlet manifold 13. The laminated sealing member 30 may be provided so as to surround the cathode fluid inlet manifold 14. The laminated sealing member 30 may be provided so as to surround the cathode fluid outlet manifold 15.

[0032] The laminated sealing member 30 is a member for sealing gaps between the electrode plate 10 and the electrode plate outer frame 11 and the flow path plate 20 and the flow path plate outer frame 21 when they are stacked together to prevent anode fluid and cathode fluid from leaking out through the gaps. The laminated sealing member 30 may be made of an elastic material such as rubber. In this case, when the electrode plate 10 and the electrode plate outer frame 11 and the flow path plate 20 and the flow path plate outer frame 21 are stacked and fastened together in a direction toward each other, the laminated sealing member 30 is compressed between the electrode plate outer frame 11 and the flow path plate outer frame 21, and the resulting reaction force seals the gaps between the components. Alternatively, the sealing member 30 may be an adhesive. In this case, when the electrode plate 10 and the electrode plate outer frame 11 and the flow path plate 20 and the flow path plate outer frame 21 are stacked together and fastened together in a direction toward each other, the electrode plate outer frame 11 and the flow path plate outer frame 21 are adhered to each other, thereby sealing the gaps between the components.

[0033] The electrode plate outer frame 11 may be made of an electrically insulating material, such as a resin material, such as fluororesin, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or polyethylene naphthalate (PEN), or a rubber material, such as fluororubber, ethylene propylene diene rubber (EPDM), or silicone rubber. Alternatively, the electrode plate outer frame 11 may be made by coating the surface of a conductive base material with an electrically insulating material. It is sufficient that the electrode plate outer frame 11 is provided with an electrically insulating material at least in the portions that come into contact with the anode fluid and the cathode fluid.

[0034] Fig. 9 is an exploded perspective view of the flow path plate 20 and the flow path plate outer frame 21 according to this embodiment. Fig. 10 is a plan view of the flow path plate 20 and the flow path plate outer frame 21 according to this embodiment. Fig. 11 is a view of the flow path plate 20 and the flow path plate outer frame 21 of Fig. 10 as seen from the back side. Fig. 12 is a cross-sectional view taken along line E-E of Fig. 10. Fig. 13 is a view showing a stack of electrochemical cells 2.

[0035] As shown in FIGS. 8 to 13, the flow path plate 20 according to this embodiment has an anode flow path 26 and a cathode flow path 28. The anode flow path 26 and the cathode flow path 28 are disposed on both sides of the flow path plate 20. The anode flow path 26 is disposed on the surface of the flow path plate 20 facing the anode electrode 17 (the lower side in FIGS. 8 and 12), and the cathode flow path 28 is disposed on the surface of the flow path plate 20 facing the cathode electrode 18 (the upper side in FIGS. 8 and 12). The anode flow path 26 is disposed opposite the anode electrode 17 of the electrode plate 10. The cathode flow path 28 is disposed opposite the cathode electrode 18 of the electrode plate 10.

[0036] The anode flow channel 26 is configured to allow the anode fluid to flow through it. As shown in FIGS. 11 and 12, the anode flow channel 26 may include a plurality of recesses recessed from one main surface of the flow channel plate 20. That is, the anode flow channel 26 may be composed of a plurality of recesses through which the anode fluid flows. Here, the anode flow channel 26 can also be said to include a plurality of protrusions protruding from the groove bottoms (bottoms of the recesses) of the flow channel plate 20, or to be composed of a plurality of protrusions through which the anode fluid flows between adjacent protrusions. As shown in FIG. 11, the anode flow channel 26 may be a serpentine flow channel having a plurality of bends.

[0037] The cathode flow path 28 is configured to allow the cathode fluid to flow through it. As shown in Figures 8, 10, and 12, the cathode flow path 28 may include a plurality of protrusions protruding from the other main surface of the flow path plate 20. That is, the cathode flow path 28 may be configured with a plurality of protrusions through which the cathode fluid flows between adjacent protrusions. As shown in Figures 8 and 10, the cathode flow path 28 may be a serpentine flow path having a plurality of bends.

[0038] The anode flow channel 26 and the cathode flow channel 28 may be formed by pressing a thin plate that will become the flow channel plate 20 from one main surface. That is, by pressing, a plurality of recesses may be formed on one main surface of the flow channel plate 20 and a plurality of protrusions may be formed on the other main surface, with the plurality of recesses formed on the one main surface serving as the anode flow channel 26 and the plurality of protrusions formed on the other main surface serving as the cathode flow channel 28. Forming the anode flow channel 26 and the cathode flow channel 28 by pressing facilitates mass production of the flow channel plate 20, thereby reducing the manufacturing cost of the electrochemical cell 2.

[0039] 8 to 13, the flow path plate 20 may have protrusions 27a and 27b that protrude outward beyond the anode electrode 17 and the cathode electrode 18 in a plan view. The protrusion 27a protrudes toward a cathode fluid inlet manifold 24 of the flow path plate outer frame 21, which will be described later. The protrusion 27b protrudes toward a cathode fluid outlet manifold 25 of the flow path plate outer frame 21, which will be described later.

[0040] 11 , the protruding portions 27a, 27b are provided with a flow path that continues from the anode flow path 26. That is, the anode flow path 26 is formed to extend to the protruding portions 27a, 27b. The anode flow paths 26 of the protruding portions 27a, 27b face the electrode plate 10-side ends of the anode connection grooves 19a, 19b in the electrode plate outer frame 11 in the stacking direction and communicate with the anode connection grooves 19a, 19b in the stacking direction. Therefore, the anode fluid that has flowed through the anode connection groove 19a in the electrode plate outer frame 11 flows in the stacking direction and into the anode flow path 26 in the flow path plate 20. The anode fluid that has flowed through the anode flow path 26 in the flow path plate 20 flows in the stacking direction and into the anode connection groove 19b in the electrode plate outer frame 11.

[0041] 10 , the protrusions 27a and 27b are provided with a flow path that continues from the cathode flow path 28. That is, the cathode flow path 28 is formed to extend to the protrusions 27a and 27b. The cathode flow paths 28 of the protrusions 27a and 27b extend to and communicate with the cathode communication grooves 29a and 29b of the flow path plate outer frame 21, which will be described later. Therefore, the cathode fluid that has flowed through the cathode communication groove 29a of the flow path plate outer frame 21 flows into the cathode flow path 28 of the flow path plate 20. Then, the cathode fluid that has flowed through the cathode flow path 28 of the flow path plate 20 flows into the cathode communication groove 29b of the flow path plate outer frame 21.

[0042] The flow path plate 20 may be made of a conductive material such as carbon, a mixture of carbon and resin, or metal. Alternatively, the flow path plate 20 may be made of a conductive material whose surface is coated with a conductive coating agent for purposes such as increasing the corrosion potential or reducing contact resistance.

[0043] As shown in Figs. 8 to 13, a flow path plate outer frame 21 is disposed on the outside of the flow path plate 20. The flow path plate outer frame 21 is joined to the flow path plate 20. The flow path plate outer frame 21 may be joined to the outer periphery of the flow path plate 20. Furthermore, as shown in Figs. 8 and 12, the flow path plate outer frame 21 may be overlapped in the stacking direction and joined to a portion of the flow path plate 20 where no flow path is formed. In this case, the joining area of ​​the joint between the flow path plate 20 and the flow path plate outer frame 21 can be increased, and the sealing performance at the joint can be improved.

[0044] 8 to 13, the flow path plate outer frame 21 has an anode fluid inlet manifold 22, an anode fluid outlet manifold 23, a cathode fluid inlet manifold 24, and a cathode fluid outlet manifold 25. These manifolds 22, 23, 24, and 25 are each provided at a distance from the flow path plate 20. These manifolds 22, 23, 24, and 25 each pass through the flow path plate outer frame 21 in the thickness direction (stacking direction).

[0045] 3 and 4, when the electrode plate 10 and electrode plate outer frame 11 are stacked on the flow path plate 20 and flow path plate outer frame 21, the communication holes 22, 23, 24, and 25 overlap with the corresponding communication holes 12, 13, 14, and 15. In other words, the anode fluid inlet communication holes 12 and 22, the anode fluid outlet communication holes 13 and 23, the cathode fluid inlet communication holes 14 and 24, and the cathode fluid outlet communication holes 15 and 25 are all connected in the stacking direction. The anode fluid inlet manifolds 12 and 22 communicate with the anode fluid inlet metal pipe 22a, the anode fluid outlet manifolds 13 and 23 communicate with the anode fluid outlet metal pipe 23b, the cathode fluid inlet manifolds 14 and 24 communicate with the cathode fluid inlet metal pipe 24c, and the cathode fluid outlet metal pipe 25d communicates with the cathode fluid outlet manifolds 15 and 25. Anode fluid supplied from the outside flows into the anode fluid inlet manifolds 12 and 22 through the anode fluid inlet metal pipe 22a. After the electrochemical reaction has occurred in the anode flow path 26, the anode fluid flows from the anode fluid outlet manifolds 13 and 23 through the anode fluid outlet metal pipe 23b and out to the outside. Cathode fluid supplied from the outside flows into the cathode fluid inlet manifolds 14 and 24 through the cathode fluid inlet metal pipe 24c. After the electrochemical reaction has occurred in the cathode flow channel 28, the cathode fluid flows from the cathode fluid outlet manifolds 15 and 25 through the cathode fluid outlet metal pipe 25d to the outside.

[0046] 8 and 10 , the flow path plate outer frame 21 has cathode communication grooves 29a and 29b. The cathode communication groove 29a connects the cathode fluid inlet manifold 24 with the cathode flow path 28 of the flow path plate 20. That is, the cathode communication groove 29a allows the cathode fluid to flow from the cathode fluid inlet manifold 24 to the cathode flow path 28 of the flow path plate 20. The cathode communication groove 29b connects the cathode flow path 28 of the flow path plate 20 with the cathode fluid outlet manifold 25. That is, the cathode communication groove 29b allows the cathode fluid to flow from the cathode flow path 28 of the flow path plate 20 to the cathode fluid outlet manifold 25.

[0047] As shown in Figures 8 and 10, the cathode connecting grooves 29a, 29b may include multiple grooves formed on the surface of the flow path plate outer frame 21. That is, the cathode connecting grooves 29a, 29b may be composed of multiple grooves through which the anode fluid flows. Also, as shown in Figures 8 and 10, the cathode connecting grooves 29a, 29b may extend from the communication holes 24, 25 to the flow path plate 20. Also, as shown in Figures 8 and 10, the cathode connecting grooves 29a, 29b may be parallel flow paths that extend linearly.

[0048] 8 and 10 , the flow path plate outer frame 21 may have a laminated sealing member 30, similar to the electrode plate outer frame 11. The laminated sealing member 30 may be provided so as to surround the cathode fluid inlet manifold 24, the cathode communication groove 29a, the flow path plate 20, the cathode communication groove 29b, and the cathode fluid outlet manifold 25. The laminated sealing member 30 may also be provided so as to surround the anode fluid inlet manifold 22. The laminated sealing member 30 may also be provided so as to surround the anode fluid outlet manifold 23.

[0049] The flow path plate outer frame 21 may be made of an electrically insulating material, such as a resin material such as fluororesin, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or polyethylene naphthalate (PEN), or a rubber material such as fluororubber, ethylene propylene diene rubber (EPDM), or silicone rubber. Alternatively, the flow path plate outer frame 21 may be made by coating the surface of a conductive base material with an electrically insulating material. It is sufficient that the flow path plate outer frame 21 is provided with an electrically insulating material at least in the portions that come into contact with the anode fluid and the cathode fluid. [Example of electrochemical cell stack operation] An example of the operation of the electrochemical cell stack 1 of this embodiment configured as described above will now be described. First, a cathode fluid and an anode fluid are supplied to the electrochemical cell stack 1. The cathode fluid supplied to the electrochemical cell stack 1 flows through the cathode fluid inlet manifolds 14, 24 of each electrochemical cell 2 through the cathode fluid inlet metal pipe 24c. The cathode fluid then flows from the cathode fluid inlet manifolds 14, 24 into the cathode communication groove 29a in the flow path plate outer frame 21 and flows through the cathode communication groove 29a. Next, the cathode fluid reaches the end of the cathode communication groove 29a on the flow path plate 20 side and flows into the cathode flow path 28 in the flow path plate 20. The cathode fluid then flows through the cathode flow path 28 while contacting the cathode electrode 18 of the electrode plate 10.

[0050] The anode fluid supplied to the electrochemical cell stack 1 flows through the anode fluid inlet metal pipe 22a into the anode fluid inlet manifolds 12, 22 of each electrochemical cell 2. The anode fluid then flows from the anode fluid inlet manifolds 12, 22 into the anode communication groove 19a in the electrode plate outer frame 11, and flows through the anode communication groove 19a. The anode fluid then reaches the end of the anode communication groove 19a on the electrode plate 10 side, flows in the stacking direction, and flows into the anode flow path 26 in the flow path plate 20. The anode fluid then flows through the anode flow path 26 in the flow path plate 20 while coming into contact with the anode 17 of the electrode plate 10.

[0051] At least a portion of the constituent substances of the cathode fluid in contact with the cathode electrode 18 and the anode fluid in contact with the anode electrode 17 reacts with the catalyst attached to the electrodes and becomes ionized. In this state, when a predetermined voltage is applied to both ends of the electrochemical cell stack 1 in the stacking direction, a potential difference is generated between the cathode electrode 18 and the anode electrode 17 across the electrically insulating diaphragm 16 of the electrode plate 10. This causes certain ionized substances in the fluids to pass through the diaphragm 16, causing an electrochemical reaction that changes the material composition of the cathode fluid and the anode fluid.

[0052] For example, by supplying water (HO) to the anode side, a water electrolysis reaction can be achieved in which hydrogen (H) is extracted from the cathode outlet side. Alternatively, by supplying water (HO) to the anode side and carbon dioxide (CO) to the cathode side, a carbon dioxide electrolysis reaction can be achieved in which a mixed gas containing carbon monoxide (CO) is extracted from the cathode outlet side.

[0053] After the electrochemical reaction, the cathode fluid flows from the cathode flow paths 28 in the flow path plate 20 into the cathode communication groove 29b in the flow path plate outer frame 21. The cathode fluid then flows through the cathode communication groove 29b in the flow path plate outer frame 21. After flowing through the cathode communication groove 29b in the flow path plate outer frame 21, the cathode fluid reaches the cathode fluid outlet manifolds 15, 25. The cathode fluid then flows from the cathode fluid outlet manifolds 15, 25 through the cathode fluid outflow metal pipe 25d to the outside.

[0054] After the electrochemical reaction, the anode fluid flows from the anode flow channel 26 in the flow channel plate 20 in the stacking direction and enters the anode communication groove 19b in the electrode plate outer frame 11. The anode fluid then flows into the anode communication groove 19b in the electrode plate outer frame 11. After flowing through the anode communication groove 19b in the electrode plate outer frame 11, the anode fluid reaches the anode fluid outlet manifolds 13, 23. The anode fluid then flows from the anode fluid outlet manifolds 13, 23 through the anode fluid outflow metal pipe 23b to the outside.

[0055] [Example of configuration of insulating joints and metal piping] Here, detailed configuration examples of the insulating joint 7 and the metal pipes 22a, 23b, 24c, and 25d will be described using Figures 14 and 15, while also referring to Figures 1 and 2. Figure 14 is a cross-sectional view taken along line AA in Figure 2. Figure 15 is a cross-sectional view taken along line BB in Figure 2. Figure 14 also shows an enlarged view of region A3, and Figure 15 also shows an enlarged view of region A4.

[0056] For the metal pipes 22a, 23b, 24c, and 25d, highly rigid metal members such as metal plates are used to withstand the internal pressure of the anode fluid or cathode fluid. In this case, the metal pipes 22a, 23b, 24c, and 25d, which are metal members, have the same potential as the anode fluid F9 or cathode fluid F9, so the metal plate 4 and the metal pipes 22a, 23b, 24c, and 25d must be electrically insulated. For this reason, insulating joints 7 made of an electrically insulating material are sandwiched between the metal plate 4 and the metal pipes 22a, 23b, 24c, and 25d to provide electrical insulation.

[0057] 14 and 15, insulating joint 7 has main body 7bo that surrounds and is connected to the outer periphery of cathode fluid outlet metal pipe 25d, and convex portion 7co that is integral with main body 7bo and is inserted into and surrounds the wall surface of the recessed gap in insulating plate 3. Here, the cathode fluid outlet metal pipe 25d will be described, but insulating joints 7 of similar shapes are also configured for metal pipes 22a, 23b, and 24c.

[0058] A recessed void surrounding the first hole portion of the insulating plate is formed in the flat portion of the insulating plate 3 that is surrounded by the upper end of the inner wall of the second hole portion in the metal plate 4. That is, an annular groove portion 73S that is a recessed void is formed in the insulating plate 3 along the outer periphery of the cathode fluid outflow metal pipe 25d.

[0059] The convex portion 7co of the insulating joint 7 is fitted into the annular groove 73S. For example, if the outer periphery of the cathode fluid outlet metal pipe 25d is circular, the groove 73S is a circular groove. Alternatively, if the outer periphery of the cathode fluid outlet metal pipe 25d is square, the groove 73S is a square groove. With this configuration of the insulating joint 7, the cathode fluid outlet metal pipe 25d is insulated from the metal plate 4. Note that in this embodiment, the cross section of the convex portion 7co is square, but is not limited to this. For example, the cross section of the end shape of the convex portion 7co may be circular, triangular, or the like. Furthermore, the shape of the groove 73S may also be any shape that allows the convex portion 7co to be inserted therein.

[0060] [Clearance and creepage distance] In general, insulation between conductive parts requires that clearance distance and creepage distance be satisfied. The clearance distance is the shortest spatial distance between conductive parts. For example, if there is a groove 73S between the metal pipe 25d, which is the conductive part, and the metal plate 4, the clearance distance is measured by ignoring the groove 73S. In contrast, in this embodiment, the convex portion 7co of the insulating joint 7 is fitted into the groove 73S, so the creepage distance is satisfied.

[0061] The creepage distance is defined as the shortest distance along the surface of the insulator between two conductive members separated by an insulating barrier. For example, the creepage distance between the metal pipe 25d and the metal plate 4 is the distance along the inner surface of the groove 73S of the insulating plate 3. That is, by inserting the convex portion 7co into the groove 73S, which is a void in the recessed structure of the insulating plate 3, the creepage distance is formed in a U-shape along the inner surface of the groove 73S of the insulating plate 3. In other words, when the convex portion 7co is fitted into the groove 73S, the deeper the groove of the groove 73S, the smaller the difference between the inner diameter and the outer diameter of the convex portion 7co can be. That is, the deeper the groove of the groove 73S, the thinner the convex portion 7co can be.

[0062] [Comparative Example] 16 and 17 show comparative examples in which the insulating plate 3 does not have a groove 73S. FIG. 16 corresponds to the cross-sectional view taken along line AA in FIG. 2. FIG. 17 corresponds to the cross-sectional view taken along line BB in FIG. 2. FIG. 16 also shows an enlarged view of region A5, and FIG. 17 also shows an enlarged view of region A6. The insulating joint 7a has a main body 7boa and an upper end 7coa. As shown in FIGS. 16 and 17, when the convex portion 7co (see FIGS. 14 and 15) into which the recessed gap is inserted is not provided, the creepage distance L73a between the metal pipe 25d and the metal plate 4 in the insulating joint 7a is the distance at which the upper end 7coa of the insulating joint 7a contacts the insulating plate 3 from above. In other words, the distance along the inner surface of the groove 73S (see FIGS. 14 and 15) is required as the distance at the upper end of the insulating joint 7a. As can be seen from this, if the insulating plate 3 does not have the groove portion 73S, the thickness of the upper end side of the upper end portion 7coa increases.

[0063] FIG. 18 is a perspective view of an electrochemical cell stack 1 according to a comparative example. When an insulating joint 7a (see FIGS. 16 and 17) is used, it is necessary to thicken the insulating joint 7a to ensure a sufficient creepage distance. This increases the planar size of the metal plate 40b and other components. Furthermore, because the potential of the entire stack increases in proportion to the number of cells, increasing the number of cells further increases the required creepage distance. In contrast, the insulating joint 7 according to this embodiment has a groove 73S formed in the insulating plate 3, and the convex portion 7co of the insulating joint 7 is inserted into the groove 73S. This makes it possible to set the creepage distance to the distance along the inner surface of the groove 73S, thereby preventing an increase in the planar size of the electrochemical cell stack 1.

[0064] As described above, according to this embodiment, the metal pipes 22a, 23b, 24c, and 25d used for the inflow or outflow of the anode fluid or cathode fluid are incorporated into the metal plate 4 via the insulating joints 7. This makes it possible to electrically insulate the metal plate 4 from the metal pipes 22a, 23b, 24c, and 25d, even when the metal pipes 22a, 23b, 24c, and 25d are made of metal.

[0065] Furthermore, an annular groove 73S is formed in the insulating plate 3 along the outer periphery of the metal pipes 22a, 23b, 24c, and 25d, and a convex portion 7co that can be inserted into the groove 73S is formed on the insulating joint 7. This allows the distance along the inner surface of the groove 73S to be the creepage distance. Therefore, even when the number of stacked electrochemical cells increases and the potential of the anode fluid or cathode fluid increases, it is possible to electrically insulate the metal plate 4, which is at ground potential, from the metal pipes 22a, 23b, 24c, and 25d, which are made of metal and are at the potential of the anode fluid or cathode fluid, without increasing the outer diameter of the insulating joint 7.

[0066] (Second embodiment) The electrochemical cell stack 1 according to the second embodiment differs from the electrochemical cell stack 1 according to the first embodiment in that the shape of the insulating joint 7 is defined to be changeable depending on the number of stacked electrochemical cells. The differences from the electrochemical cell stack 1 according to the first embodiment will be described below.

[0067] In the electrochemical cell stack 1, the number of stacked electrochemical cells 2 is changed depending on the purpose. For this reason, in the electrochemical cell stack 1 according to this embodiment, the spatial distance between the metal plate 4 and the metal pipes 22a, 23b, 24c, and 25d is specified in accordance with the voltage when the number of stacked electrochemical cells 2 is the smallest. In addition, the creepage distance between the metal plate 4 and the metal pipes 22a, 23b, 24c, and 25d is specified in accordance with the voltage when the number of stacked electrochemical cells 2 is the largest.

[0068] Figure 19 is a cross-sectional view taken along line BB in Figure 2, showing an example of an insulating joint 7c that does not have a convex portion 7co. Figure 20 is a cross-sectional view taken along line BB in Figure 2, showing an example of an insulating joint 7d that has a shorter convex portion 7cod. Figure 19 also shows an enlarged view of region A7, and Figure 20 also shows an enlarged view of region A8.

[0069] As shown in FIG. 19, the configuration is the same as that of the electrochemical cell stack 1, except that the insulating joint 7c is different from the insulating joint 7 (see FIGS. 14 and 15). That is, a cavity region 70c is formed between the metal plate 4 and the metal pipes 22a, 23b, 24c, and 25d. The insulating joint 7c is not inserted into the groove 73S. In this case, the distance along the inner surface of the groove 73S of the insulating plate 3 is the creepage distance. Meanwhile, the shortest distance between the cavity region 70c and the groove 73S is the spatial distance L73c.

[0070] As can be seen from these, the number of stacked electrochemical cells 2 is limited to a range in which insulation can be maintained within the spatial distance L73c. In other words, when the number of stacked electrochemical cells 2 is small, the convex portion 7co (see FIGS. 14 and 15) inserted into the hollow region 70c and the groove portion 73S is unnecessary. This allows the insulating joint 7c to have a simple shape without the convex portion 7co.

[0071] As shown in FIG. 20, the insulating joint 7d has the same configuration as the electrochemical cell stack 1, except that the length of the convex portion 7cod of the insulating joint 7d is shorter than the convex portion 7co of the insulating joint 7 (see FIGS. 14 and 15). In other words, the convex portion 7cod is inserted partway into the groove 73S. In this case, the distance along the inner surface of the groove 73S of the insulating plate 3 is the creepage distance. Meanwhile, the distance between the top of the convex portion 7cod and the end of the entrance of the groove 73S is the spatial distance L73d. In other words, the shortest distance on the surface of the convex portion 7cod inserted into the groove 73S is the spatial distance L73d.

[0072] As can be seen from these, the number of stacked electrochemical cells 2 is limited to a range in which insulation can be maintained within the spatial distance L73d. In other words, the maximum number max of stacked electrochemical cells 2 is limited by the creepage distance between the metal plate 4 and the metal pipes 22a, 23b, 24c, and 25d, and the spatial distance L73c is determined by the minimum number min of stacked electrochemical cells 2. In addition, the length of the convex portion 7cod is determined by the number of stacked electrochemical cells 2 between the maximum number max and the minimum number min.

[0073] As described above, according to this embodiment, the lengths of the convex portions 7co, 7cod of the insulating joints 7, 7c, 7d are configured to be changeable in accordance with the number of stacked electrochemical cells 2. This makes it possible to reduce the overall size of the insulating joint 7 in accordance with the number of stacked electrochemical cells 2. [Explanation of symbols]

[0074] 1: electrochemical cell stack, 2: electrochemical cell, 3: insulating plate, 4: metal plate, 7, 7a, 7c, 7d: insulating joint, 7co, 7cod: convex portion of insulating joint, 10: electrode plate, 11: electrode plate outer frame, 12: anode fluid inlet communication hole, 13: anode fluid outlet communication hole, 14: cathode fluid inlet communication hole, 15: cathode fluid outlet communication hole, 16: diaphragm, 17: anode electrode, 18: cathode electrode, 19a, 19b: anode connection groove, 20: flow path plate, 21: flow path plate outer frame, 22a, 23b, 24c, 25d: metal piping, 73S: groove portion of insulating plate, 70c: hollow region

Claims

1. a stack of electrochemical cells, each of which includes an electrode plate having a diaphragm, an anode electrode disposed on one main surface of the diaphragm, and a cathode electrode disposed on the other main surface of the diaphragm, and a flow path plate laminated on the electrode plate, the flow path plate being disposed opposite the anode electrode and having an anode flow path through which an anode fluid flows, and a cathode flow path being disposed opposite the cathode electrode and through which a cathode fluid flows; Insulating plates made of an electrically insulating material are placed on the upper and lower surfaces of the laminate; a metal plate that sandwiches the outer side of the insulating plate; a metal pipe communicating with the through-hole of the stack, through which either the anode fluid or the cathode fluid flows into or out of the electrochemical cell, via a first hole portion of the insulating plate and a second hole portion of the metal plate; an insulating joint for the metal pipe that insulates the metal pipe from the metal plate; An electrochemical cell stack comprising:

2. 2. The electrochemical cell stack according to claim 1, wherein a recessed void surrounding the first hole portion of the insulating plate is formed in a planar portion of the insulating plate that is surrounded by an end of an inner wall of the second hole portion of the metal plate.

3. The insulating joint includes a main body portion that surrounds and is connected to an outer periphery of the metal pipe; 3. The electrochemical cell stack according to claim 2, further comprising: a convex portion that is integral with the main body portion, surrounds a wall surface within the cavity of the recessed structure, and is inserted into the cavity in a state of contact with the wall surface.

4. The electrochemical cell stack according to claim 2 , wherein a cavity region is formed between the metal pipe and the second hole portion of the metal plate.

5. 4. The electrochemical cell stack according to claim 3, wherein a hollow region is formed between the metal pipe and the second hole portion of the metal plate, and the convex portion is inserted into a gap of the concave structure through the hollow region.

6. The electrochemical cell stack according to claim 5 , wherein a creepage distance along an inner surface of the recessed void is set to a distance that insulates the metal pipe from the metal plate.

7. 7. The electrochemical cell stack according to claim 6, wherein the number of stacked electrochemical cells is variable, and the length of the convex portion is set to a length corresponding to the number of stacked electrochemical cells.

8. The electrochemical cell stack according to claim 7 , wherein the insulating joint has a shape that does not include the convex portion.

9. The electrochemical cell stack according to claim 8 , wherein a spatial distance that is the shortest distance of the voids in the recessed structure is formed to be a distance that insulates the metal pipe from the metal plate.

10. 10. The electrochemical cell stack according to claim 9, wherein a spatial distance that is the shortest distance between the metal pipe in the cavity region and the metal plate is formed to be a distance that insulates the metal pipe from the metal plate.

11. 4. The electrochemical cell stack according to claim 1, wherein the metal piping has the same potential as either the anode fluid or the cathode fluid, and the metal plate is maintained at ground potential.

12. 4. The electrochemical cell stack according to claim 3, wherein the convex portion is inserted into the gap of the concave structure of the insulating plate, so that the creeping distance between the metal pipe and the metal plate is formed in a U-shape along the gap of the concave structure.

13. The electrochemical cell comprises: an electrode plate outer frame disposed outside the electrode plate; a flow path plate outer frame arranged outside the flow path plate, the electrode plate outer frame and the flow path plate outer frame each have an anode fluid communication hole and a cathode fluid communication hole that communicate with each other in the stacking direction, the flow path plate outer frame has either an anode communication groove that communicates the anode fluid communication hole with the anode flow path of the flow path plate or a cathode communication groove that communicates the cathode fluid communication hole with the cathode flow path of the flow path plate, 4. The electrochemical cell stack according to claim 1, wherein the electrode plate outer frame has a connecting groove for the other of the anode connecting groove and the cathode connecting groove.

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