Cell stack and hydrogen production device

Abstract

A cell stack according to the present invention is to be provided to a hydrogen production device and comprises: a layered body that includes a plurality of electrolysis cells; a first end plate and a second end plate that are provided on respective sides of the layered body; and a fastening mechanism that fastens the first end plate and the second end plate toward each other. The fastening mechanism has an elastic member that presses the first end plate toward the second end plate. Each of the plurality of electrolysis cells has: an anode, anion exchange membrane, and cathode set; and separators that are provided on respective sides of the set. The separators have an electroconductive plate and a frame body that supports an outer peripheral edge part of the electroconductive plate. The frame body is made of resin.

Description

Cell stack and hydrogen production device

[0001] The present disclosure relates to a cell stack and a hydrogen production device. This application claims priority from Japanese Patent Application No. 2024-056509, filed March 29, 2024. The entire contents of the Japanese application are incorporated herein by reference.

[0002] Patent Document 1 discloses a water electrolysis device that generates hydrogen by electrolyzing pure water. The water electrolysis device includes a stack having multiple electrolytic cells and separators arranged on both sides of each of the multiple electrolytic cells. Each electrolytic cell has an anode-side power supply, a cathode-side power supply, and a hydrogen ion-permeable solid polymer membrane arranged between the anode-side power supply and the cathode-side power supply. The anode-side power supply is made of a sintered titanium body. The cathode-side power supply is made of a sintered stainless steel body. Each separator is made of a metal. In the water electrolysis device, pure water is supplied to the anode-side power supply and the cathode-side power supply. A voltage is applied between the anode-side power supply and the cathode-side power supply to pass a current, thereby generating oxygen gas on the anode side and hydrogen gas on the cathode side.

[0003] Japanese Patent Application Laid-Open No. 2003-147562

[0004] The cell stack disclosed herein is a cell stack for use in a hydrogen production device, and includes a stack having multiple electrolysis cells, a first end plate and a second end plate disposed on either side of the stack, and a clamping mechanism that clamps the first end plate and the second end plate toward each other. The clamping mechanism has an elastic member that presses the first end plate toward the second end plate. Each of the multiple electrolysis cells includes an assembly of an anode, an anion exchange membrane, and a cathode, and separators disposed on either side of the assembly. The separator includes a conductive plate and a frame that supports the outer peripheral edge of the conductive plate. The frame is made of resin.

[0005] Fig. 1 is a perspective view showing an outline of a hydrogen production device according to an embodiment. Fig. 2 is a side view showing an outline of a hydrogen production device according to an embodiment. Fig. 3 is a partial cross-sectional view of an electrolysis cell provided in the hydrogen production device according to an embodiment. Fig. 4 is a plan view showing a separator provided in the hydrogen production device according to an embodiment. Fig. 5 is a plan view showing a first end plate provided in the hydrogen production device according to an embodiment.

[0006] [Problem to be Solved by the Present Disclosure] A hydrogen production device that can be used for a long period of time is desired.

[0007] An object of the present disclosure is to provide a cell stack that can be used to construct a hydrogen production device that can be used for a long period of time.

[0008] [Advantages of the Present Disclosure] The cell stack of the present disclosure makes it possible to construct a hydrogen production device that can be used for a long period of time.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be listed and described.

[0010] (1) A cell stack according to one aspect of the present disclosure is a cell stack for use in a hydrogen production device, comprising: a stack having a plurality of electrolysis cells; a first end plate and a second end plate disposed on either side of the stack; and a clamping mechanism configured to clamp the first end plate and the second end plate toward each other. The clamping mechanism includes an elastic member configured to press the first end plate toward the second end plate. Each of the plurality of electrolysis cells includes an assembly of an anode, an anion exchange membrane, and a cathode, and separators disposed on either side of the assembly. The separator includes a conductive plate and a frame configured to support the outer peripheral edge of the conductive plate. The frame is made of resin.

[0011] A hydrogen production device constructed using the cell stack of (1) uses an electrolyte that is an alkaline aqueous solution. The electrolyte has a higher electrical conductivity than pure water. In the cell stack of (1), each of the multiple separators in the stack has a frame made of resin, which tends to provide high electrical insulation against the electrolyte. In the hydrogen production device, the temperature of the electrolyte increases during operation. That is, in the hydrogen production device, the temperature difference between the electrolyte when stopped and when operating is large. The stack has multiple frames made of resin. The thermal expansion coefficient of resin is often higher than that of metals and ceramics. Therefore, in the cell stack of (1), the thermal expansion of the stack is likely to increase due to the large temperature difference. In the cell stack of (1), the tightening mechanism that tightens the first end plate and the second end plate in a direction toward each other is equipped with an elastic member, which easily absorbs the thermal expansion. Although resin has lower strength than the above-mentioned metals such as titanium and stainless steel, the cell stack of (1) above can easily absorb the thermal expansion and contraction through elastic deformation of the elastic member, which reduces damage to the frame caused by the thermal expansion and contraction. Therefore, the cell stack of (1) above can be used to construct a hydrogen production device that can be used for a long period of time.

[0012] (2) In the cell stack of (1), the tightening mechanism may include a plurality of rods that penetrate the first end plate and the second end plate, and a first nut attached to a first end of each of the plurality of rods, and the elastic member is disposed on an outer periphery of each of the plurality of rods between the first end plate and the first nut.

[0013] The tightening mechanism facilitates assembly of a cell stack that easily absorbs the thermal expansion and contraction, and therefore the cell stack of (2) above has excellent productivity.

[0014] (3) In the cell stack of (2), the first end plate and the second end plate may have a first portion overlapping the stack and a second portion disposed on an outer periphery of the first portion, and each of the plurality of rods may pass through the second portion.

[0015] In the cell stack of (3) above, each rod penetrates the first end plate and the second end plate but does not penetrate the stack body. The cell stack of (3) above can reduce the outline size of the stack body compared to when each rod penetrates the stack body. This is because when each rod penetrates the stack body, the outline size of the stack body increases by the size of the through-hole through which each rod is inserted.

[0016] Between adjacent frames, an annular sealing member may be disposed near the outer periphery of the frame. The sealing member prevents leakage of the electrolyte to the outside of the stack. In the cell stack of (3) above, each rod is disposed outside the stack. Therefore, since each rod is disposed near the sealing member, the tightening mechanism can easily compress the multiple frames effectively so that the sealing member is effectively compressed. Therefore, the cell stack of (3) above can easily and effectively prevent leakage of the electrolyte.

[0017] (4) In the cell stack of (3), the first end plate and the second end plate may have a first rib provided annularly along an outer periphery of a surface of the second portion opposite the stack, and each of the plurality of rods may pass through the first rib.

[0018] The first end plate and the second end plate having the first rib have higher mechanical strength than the first end plate and the second end plate not having the first rib.

[0019] (5) In the cell stack of (4) above, the first end plate and the second end plate may have second ribs arranged in a lattice pattern so as to connect the inner circumferential surfaces of the first ribs.

[0020] The first and second end plates having the second ribs have even higher mechanical strength. The first and second end plates have recesses formed between the first and second ribs. The thickness of the recessed portions of the first and second end plates is thinner than the thickness of the first and second ribs. Therefore, the weight of the first and second end plates can be reduced compared to first and second end plates that do not have recesses and have the same thickness as the first and second ribs.

[0021] (6) In the cell stack of (5) above, the second ribs may be arranged more densely in the center of the surface than in the periphery.

[0022] As described above, because the rods are arranged on the outside of the stack, the center of the surface, which is located farthest from the rods, is most susceptible to bending due to thermal expansion and contraction. In the cell stack of (6) above, the center of the surface has high mechanical strength due to the second ribs. Therefore, the cell stack of (6) above is less susceptible to bending than when the second ribs are provided at equal intervals on the surface.

[0023] (7) In the cell stack of any one of (1) to (6) above, the number of separators may be 15 or more.

[0024] Even if there are 15 or more separators, the thermal expansion and contraction is easily absorbed.

[0025] (8) In the cell stack according to any one of (1) to (7) above, the elastic member may be a coil spring.

[0026] The coil spring easily absorbs the thermal expansion and contraction.

[0027] (9) The cell stack of any one of (1) to (8) above may include a first current collector plate disposed between the stack and the first end plate, a second current collector plate disposed between the stack and the second end plate, a supply / discharge plate disposed between the first current collector plate and the first end plate, and piping connected to the supply / discharge plate, wherein the piping includes a supply pipe through which an electrolytic solution supplied to the anode flows, a first exhaust pipe through which oxygen gas from the anode flows, and a second exhaust pipe through which hydrogen gas from the cathode flows.

[0028] The cell stack of (9) above is provided with a supply / discharge plate and a supply pipe, which makes it easy to supply the electrolyte to the anode. The cell stack of (9) above is provided with a supply / discharge plate and a first discharge pipe, which makes it easy to discharge oxygen gas from the anode. The cell stack of (9) above is provided with a supply / discharge plate and a second discharge pipe, which makes it easy to discharge hydrogen gas from the cathode. If the cell stack of (9) above does not have a supply pipe that supplies the electrolyte to the cathode, the amount of electrolyte present at the cathode is small, so it is easy to discharge low-humidity hydrogen gas from the second discharge pipe.

[0029] (10) In the cell stack of (9) above, the connection points of the supply pipe, the first exhaust pipe, and the second exhaust pipe with the supply and exhaust plate may be arranged to extend in a direction perpendicular to the surface of the first end plate opposite the stack.

[0030] In the cell stack of (10) above, each pipe can be easily connected to the supply / discharge plate.

[0031] (11) In the cell stack of (9) or (10), the first current collector plate and the second current collector plate may have terminal portions that protrude from an outer peripheral edge of the stack, and the terminal portions extend in a direction perpendicular to the direction in which the connection points extend.

[0032] In the cell stack of (11) above, even if electrolyte leaks from any of the tubes, the leaked electrolyte is unlikely to come into contact with the terminals. When connecting each tube to the supply / discharge plate, the terminals are unlikely to get in the way, making it easy to connect each tube to the supply / discharge plate.

[0033] (12) In the cell stack of any one of (1) to (11) above, the resin may be a resin that has alkali resistance to an electrolyte solution having a pH of 8 or higher.

[0034] A frame made of the above resin can be used for a long period of time because damage caused by contact with the electrolyte is reduced.

[0035] (13) In the cell stack of any one of (1) to (12) above, the resin may be heat resistant to temperatures of 80° C. or less.

[0036] A frame made of the above resin can be used for a long period of time because damage caused by temperature rise during operation is reduced.

[0037] (14) A hydrogen production device according to one aspect of the present disclosure includes a cell stack according to any one of (1) to (13) above.

[0038] The hydrogen production device (14) can be used for a long period of time.

[0039] <Details of the Embodiments of the Present Disclosure> Specific examples of the cell stack and hydrogen production device of the present disclosure will be described below with reference to Figures 1 to 5. The same reference numerals in the figures indicate the same objects. The shapes, sizes, positional relationships, etc. shown in each figure are expressed for the purpose of clarifying the description and do not necessarily represent the actual shapes, sizes, positional relationships, etc. Note that the present invention is not limited to the configurations shown in the embodiments, but is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0040] «Embodiment» [Hydrogen Production Apparatus] The hydrogen production apparatus 1 of the embodiment shown in FIG. 1 produces hydrogen by electrolyzing water contained in a supplied electrolytic solution. The hydrogen production apparatus 1 generates oxygen in addition to producing hydrogen through water electrolysis. The hydrogen production apparatus 1 can also be used as an apparatus for producing oxygen. The hydrogen production apparatus 1 includes a cell stack 2. The cell stack 2 includes a stack 2a (FIG. 2), a first end plate 91, a second end plate 92, and a clamping mechanism 93. As shown in FIG. 2, the stack 2a includes a plurality of electrolysis cells 20. The first end plate 91 and the second end plate 92 are disposed on both sides of the stack 2a. The both sides of the stack 2a refer to both sides in the direction in which the plurality of electrolysis cells 20 are stacked. The clamping mechanism 93 clamps the first end plate 91 and the second end plate 92 toward each other. One of the features of the hydrogen production device 1 is that each separator 3 has a specific configuration and that the clamping mechanism 93 has an elastic member 96. In Fig. 2 , only the appearance of the separator 3 of the electrolytic cell 20 is shown. For ease of explanation, the separator 3, first current collector plate 41, second current collector plate 42, supply / discharge plate 5, folding plate 6, first end plate 91, and second end plate 92 of the electrolytic cell 20 are hatched in Fig. 2 .

[0041] [Cell Stack] The cell stack 2 of this example is constructed by sandwiching the laminate 2a between a first end plate 91 and a second end plate 92 on both sides, and fastening the first end plate 91 and the second end plate 92 with a fastening mechanism 93. The cell stack 2 of this example further includes a first current collecting plate 41, a second current collecting plate 42, a supply / discharge plate 5, and a folding plate 6.

[0042] [Electrolytic Cell] As shown in Fig. 3 , each electrolytic cell 20 includes an assembly in which an anode 22, an anion exchange membrane (AEM) 21, and a cathode 23 are stacked, and separators 3 arranged on both sides of the assembly. That is, the hydrogen production device 1 is an AEM-type hydrogen production device. The anion exchange membrane 21 is arranged between the anode 22 and the cathode 23. A known anion exchange membrane can be used as the anion exchange membrane 21. The anode 22 includes an anode catalyst 221 and an anode diffusion layer 222. The cathode 23 includes a cathode catalyst 231 and a cathode diffusion layer 232. Known materials can be used for the anode catalyst 221, the anode diffusion layer 222, the cathode catalyst 231, and the cathode diffusion layer 232. Each electrolysis cell 20 is configured by stacking an anode diffusion layer 222, an anode catalyst 221, an anion exchange membrane 21, a cathode catalyst 231, and a cathode diffusion layer 232 in this order. The anode catalyst 221, the anion exchange membrane 21, and the cathode catalyst 231 may be bonded together to form a catalyst coated membrane (CCM), or the anode diffusion layer 222, the anode catalyst 221, the anion exchange membrane 21, the cathode catalyst 231, and the cathode diffusion layer 232 may be bonded together to form a membrane electrode assembly (MEA). All of the electrolysis cells 20 are electrically connected in series.

[0043] As shown in FIG. 2 , the separator 3 separates adjacent assemblies. When the first current collector 41 is the cathode, a separator 3 is disposed between adjacent assemblies, between the cathode 23 located at one end of the stacking direction of the laminate 2a and the first current collector 41, and between the anode 22 located at the other end of the stacking direction of the laminate 2a and the second current collector 42. One separator 3 is disposed between each of the assemblies. One assembly is disposed between adjacent separators 3. At the intermediate position in the stacking direction of the laminate 2a, the anode 22, the anion exchange membrane 21, the cathode 23, and the separator 3 are repeatedly stacked in this order. The separator 3 at the end adjacent to the first current collector 41, the separator 3 at the end adjacent to the second current collector 42, and the intermediate separator 3 located between these end separators 3 all have the same configuration. As shown in FIG. 4, the separator 3 is composed of a conductive plate 31 and a frame 32 that supports the outer peripheral edge of the conductive plate 31 .

[0044] The conductive plate 31 may be formed of, for example, a first conductive material or a composite material. The conductive plate 31 may be formed of a coated conductive plate. The coated conductive plate includes a substrate and one or more coating layers covering the surface of the substrate. The substrate is formed of a first conductive material. The coating layer is formed of a second conductive material. The composite material includes the first conductive material and a resin. The first conductive material may be a metal or a non-metal. The metal may be, for example, one or more selected from the group consisting of iron alloys, titanium, titanium alloys, copper, copper alloys, nickel, nickel alloys, aluminum, aluminum alloys, and zinc. The iron alloy may be, for example, steel. The steel may be various steels such as stainless steel, silicon chromium steel, or carbon steel. The non-metal may be a carbon material or a conductive ceramic. The carbon material may be, for example, graphite, carbon black, or diamond-like carbon. The second conductive material may be, for example, a material that has better oxidation resistance to an electrolyte than the first conductive material. The second conductive material is, for example, one or more metals selected from the group consisting of platinum group metals, gold, silver, and nickel. The resin in the composite material is, for example, one selected from the group consisting of polyethylene resin, polypropylene resin, polytetrafluoroethylene resin, perfluoroalkoxyalkane resin, perfluoroethylenepropene copolymer, and polyphenylene sulfide resin.

[0045] The inner peripheral edge 32i of the frame 32 has, for example, a step or recess, although not shown. The conductive plate 31 is disposed in this step or recess. The conductive plate 31 and the frame 32 are prepared, and the conductive plate 31 is disposed in the step or recess of the frame 32, thereby forming the separator 3 in which the conductive plate 31 and the frame 32 are combined. The frame 32 may be formed, for example, by injection molding on the outer peripheral edge of the conductive plate 31. The conductive plate 31 is prepared, and the outer peripheral edge of the conductive plate 31 is injection molded to form the separator 3 in which the frame 32 is integrated with the outer peripheral edge of the conductive plate 31.

[0046] The shapes of the outer peripheral edge 32e and inner peripheral edge 32i of the frame 32 correspond to the shape of the outer peripheral edge of the conductive plate 31. In this embodiment, the frame 32 has a rectangular frame shape in a plan view. The frame 32 has a first side 321 and a second side 322 facing each other, and a third side 323 and a fourth side 324 connecting both ends of the first side 321 and the second side 322. The first side 321 is located at the bottom of FIG. 4 and extends in the left-right direction. The second side 322 is located at the top of FIG. 4 and extends in the left-right direction. The third side 323 is located on the left side of FIG. 4 and extends in the up-down direction. The third side 323 connects the left ends of the first side 321 and the second side 322. The fourth side 324 is located on the right side of FIG. 4 and extends in the vertical direction. The fourth side 324 connects the right ends of the first side 321 and the second side 322. In FIG. 4 , the lengths of the first side 321 and the second side 322 along their longitudinal directions, i.e., the lengths along the left and right directions, are shorter than the lengths of the third side 323 and the fourth side 324 along their longitudinal directions, i.e., the lengths along the top and bottom directions. Unlike FIG. 4 , the lengths of the first side 321 and the second side 322 along their longitudinal directions may be longer than the lengths of the third side 323 and the fourth side 324 along their longitudinal directions, or may be equal to the lengths of the third side 323 and the fourth side 324 along their longitudinal directions.

[0047] The frame 32 has an opening that exposes the conductive plate 31. A first recess is formed by the inner circumferential surface of the frame 32 and the first main surface of the conductive plate 31. The first main surface of the conductive plate 31 faces the anode 22. An anode diffusion layer 222 is disposed in the first recess. A second recess is formed by the inner circumferential surface of the frame 32 and the second main surface of the conductive plate 31. The second main surface of the conductive plate 31 is the surface opposite the first main surface and faces the cathode 23. A cathode diffusion layer 232 is disposed in the second recess. To the extent that such a recess can be formed, the size of the outer edge of the conductive plate 31 is made smaller than the size of the outer peripheral edge portion 32e of the frame 32.

[0048] The frame 32 is formed from a resin. The resin forming the frame 32 is an electrically insulating resin. An electrically insulating resin is a resin that has electrical insulation properties against an electrolyte solution. Since the frame 32 is formed from a resin, the outer peripheral surface of the laminate 2a is also formed from a resin. This makes it easier for the laminate 2a to have high electrical insulation against the rod 94 described below. The frame 32 may be formed from a resin that has at least one of alkali resistance and heat resistance in addition to electrical insulation properties. An alkali-resistant resin is a resin that is resistant to an electrolyte solution with a pH of 8 or higher. A heat-resistant resin is a resin that is resistant to temperatures of 80°C or lower. The resin may also be a resin that is resistant to temperatures of 50°C or higher. The resin forming the frame body 32 is, for example, one selected from the group consisting of vinyl chloride resin, polypropylene resin, polyethylene resin, fluororesin, epoxy resin, acrylonitrile butadiene styrene resin, vinylidene chloride resin, polyamide resin, polyester resin, polystyrene resin, acrylic resin, polyvinyl alcohol resin, diacetate resin, triacetate resin, polyphenylsulfone resin, and polycarbonate resin.

[0049] As shown in Figure 4, the frame 32 has a first supply manifold 33, a first supply slit 34, a first exhaust manifold 35, a first exhaust slit 36, a second exhaust manifold 37, a second exhaust slit 38, and a seal groove 39.

[0050] The first supply manifold 33 is a supply port for the electrolytic solution to the laminate 2a. The first supply manifold 33 is a through hole that penetrates the first and second main surfaces of the frame 32. The first main surface of the frame 32 is a surface that faces the same direction as the first main surface of the conductive plate 31. The second main surface of the frame 32 is a surface opposite to the first main surface of the frame 32 and faces the same direction as the second main surface of the conductive plate 31. In FIG. 4, the first main surface is shown. The first supply manifold 33 in this example is provided on the left side of the first side portion 321.

[0051] The first supply slit 34 is a flow path through which the electrolytic solution supplied from the first supply manifold 33 flows. The first supply slit 34 is a flow path that guides the electrolytic solution from the first supply manifold 33 to the inner peripheral edge 32i of the frame 32. The first supply slit 34 is a groove having a bottom surface. The first supply slit 34 is provided on the first main surface of the frame 32 so as to connect the first supply manifold 33 and the inner peripheral edge 32i.

[0052] The first exhaust manifold 35 is an outlet for the first fluid. The first fluid includes oxygen gas generated by electrolysis of water, which will be described later. The first exhaust manifold 35 is a through-hole that penetrates the first main surface and the second main surface of the frame 32. In this example, the first exhaust manifold 35 is provided to the right of the second side portion 322.

[0053] The first discharge slit 36 ​​is a flow path that allows the first fluid to flow toward the first discharge manifold 35. The first discharge slit 36 ​​is a flow path that guides the first fluid from the inner peripheral edge 32i of the frame 32 to the first discharge manifold 35. The first discharge slit 36 ​​is a groove having a bottom surface. The first discharge slit 36 ​​is provided on the first main surface of the frame 32 so as to connect the inner peripheral edge 32i and the first discharge manifold 35.

[0054] The second exhaust manifold 37 is an outlet for the second fluid. The second fluid includes hydrogen gas generated by electrolysis of water. The second exhaust manifold 37 is a through-hole that penetrates the first main surface and the second main surface of the frame 32. In this example, the second exhaust manifold 37 is provided on the left side of the second side portion 322.

[0055] The second discharge slit 38 is a flow path that allows the second fluid to flow toward the second discharge manifold 37. The second discharge slit 38 is a flow path that guides the second fluid from the inner peripheral edge 32i of the frame 32 to the second discharge manifold 37. The second discharge slit 38 is a groove having a bottom surface. The second discharge slit 38 is provided on the second main surface of the frame 32 so as to connect the inner peripheral edge 32i of the frame 32 and the second discharge manifold 37.

[0056] The seal groove 39 is provided near the outer peripheral edge 32e of at least one of the first and second main surfaces of the frame 32. The seal groove 39 is annularly provided so as to surround all of the manifolds 33, 35, 37 and the slits 34, 36. The manifolds 33, 35, 37 and the slits 34, 36 are located in the area between the inner peripheral edge of the seal groove 39 and the inner peripheral edge 32i. A seal member (not shown) is disposed in the seal groove 39. The seal member prevents the electrolyte from leaking outside the stack 2a. The seal member is, for example, an annular rubber member.

[0057] In this example, the frame 32 does not have a second supply manifold and a second supply slit, but may have a second supply manifold and a second supply slit. The second supply manifold is a supply port for the electrolytic solution. The second supply manifold is a through hole penetrating the first and second main surfaces of the frame 32. The second supply slit is a flow path through which the electrolytic solution supplied from the second supply manifold flows. The electrolytic solution supplied from the second supply manifold is the same as the electrolytic solution supplied from the first supply manifold 33. The second supply slit is a flow path that guides the electrolytic solution from the second supply manifold to the inner peripheral edge 32i of the frame 32. The second supply slit is a groove having a bottom surface. The second supply slit is provided on the second main surface of the frame 32 so as to connect the second supply manifold and the inner peripheral edge 32i of the frame 32.

[0058] The number of separators 3 is not particularly limited and can be selected appropriately. The greater the number of separators 3, the greater the number of electrolysis cells 20, and thus the greater the amount of hydrogen produced by the cell stack 2. However, the greater the number of separators 3, the greater the number of frames 32, which increases the likelihood of thermal expansion and contraction of the stack 2a (described later). The number of separators 3 is, for example, 15 or more. Even if the number of separators 3 is 15 or more, the thermal expansion and contraction of the stack 2a (described later) is easily absorbed by the elastic member 96 of the tightening mechanism 93 (described later). The number of separators 3 may be 20 or more, 30 or more, or 35 or more. The number of separators 3 is, for example, 200 or less. A cell stack 2 having 200 or fewer separators 3 is likely to be compact because the length of the stack 2a along the stacking direction is likely to be short. The number of separators 3 may be 150 or less, 125 or less, or 100 or less. That is, the number of separators 3 is 15 to 200, 20 to 150, 30 to 125, or 35 to 100.

[0059] [First Current Collector Plate and Second Current Collector Plate] The first current collector plate 41 and the second current collector plate 42 shown in Fig. 2 cause water electrolysis, which will be described later, when a voltage is applied between the two current collector plates 41, 42 from a power source (not shown). The first current collector plate 41 is disposed between the laminate 2a and the first end plate 91. The second current collector plate 42 is disposed between the laminate 2a and the second end plate 92.

[0060] As shown in Fig. 1, the first current collector 41 has a terminal portion 411 that protrudes from the outer peripheral edge of the laminate 2a (Fig. 2). The second current collector 42 has a terminal portion 421 that protrudes from the outer peripheral edge of the laminate 2a. A power source is connected to each of the terminal portions 411, 421. In this example, each of the terminal portions 411, 421 extends in a direction perpendicular to the extension direction of the pipe 7, which will be described later.

[0061] The first current collector plate 41 and the second current collector plate 42 are made of a metal, such as copper or a copper alloy.

[0062] 2 supplies the electrolytic solution to the plurality of electrolytic cells 20 and discharges fluids from the plurality of electrolytic cells 20. For this purpose, a pipe 7, which will be described later, is connected to the supply / discharge plate 5. The fluids are the first fluid and the second fluid.

[0063] The supply and discharge plate 5 is disposed at least between the first current collector plate 41 and the first end plate 91 and between the second current collector plate 42 and the second end plate 92. In this example, the supply and discharge plate 5 is disposed between the first current collector plate 41 and the first end plate 91, but is not disposed between the second current collector plate 42 and the second end plate 92. In this example, a folding plate 6 (described later) is disposed between the second current collector plate 42 and the second end plate 92. The supply and discharge plate 5 is adjacent to the first current collector plate 41 and the first end plate 91. The folding plate 6 is adjacent to the second current collector plate 42 and the second end plate 92. In the cell stack 2 of this example, the first end plate 91, the supply and discharge plate 5, the first current collector plate 41, the stack 2a, the second current collector plate 42, the folding plate 6, and the second end plate 92 are arranged in this order.

[0064] Although not shown, the supply / discharge plate 5 of this example has a first supply communication hole, a first discharge communication hole, and a second discharge communication hole that communicate with the first supply manifold 33, the first discharge manifold 35, and the second discharge manifold 37, respectively. These communication holes penetrate the first and second main surfaces of the supply / discharge plate 5. The first main surface is the surface that faces the stack 2a. The second main surface is the surface opposite the first main surface and faces the first end plate 91.

[0065] In this example, the supply / discharge plate 5 does not have a second supply passage communicating with the second supply manifold because the separator 3 does not have a second supply manifold. Unlike this example, if the separator 3 has a second supply manifold, the supply / discharge plate 5 may have a second supply passage. The second supply passage penetrates the first main surface and the second main surface of the supply / discharge plate 5.

[0066] The material of the supply / discharge plate 5 is resin. The resin forming the supply / discharge plate 5 is an electrically insulating resin. The supply / discharge plate 5 formed from such a resin also functions as a member that electrically insulates between the first end plate 91 and the first current collector plate 41. The resin forming the supply / discharge plate 5 may be formed from a resin that has at least one of alkali resistance and heat resistance in addition to electrical insulation. For the resin forming the supply / discharge plate 5, refer to the description of the resin forming the frame 32 of the separator 3. The resin forming the supply / discharge plate 5 may be the same as or different from the resin forming the frame 32.

[0067] In this example, the size of the supply / discharge plate 5 when viewed from the stacking direction of the stacked body 2a is the same as the size of the stacked body 2a when viewed from the stacking direction.

[0068] (Folding Plate) The folding plate 6 folds the electrolytic solution supplied from the supply / discharge plate 5 and returns it to the supply / discharge plate 5. The piping 7, which will be described later, is not connected to the folding plate 6. The folding plate 6 is not the supply / discharge plate 5 that supplies the electrolytic solution and discharges the gas generated by the electrolysis of water contained in the electrolytic solution. The folding plate 6 does not have a hole through which the electrolytic solution is supplied from outside the cell stack 2 and a hole through which the gas is discharged to outside the cell stack 2. The folding plate 6 in this example is disposed between the second current collector plate 42 and the second end plate 92. Unlike this example, the supply / discharge plate 5 may be disposed between the second current collector plate 42 and the second end plate 92, and the folding plate 6 may be disposed between the first current collector plate 41 and the first end plate 91. The folding plate 6 has a first main surface and a second main surface. The first main surface faces the second current collector plate 42. The second main surface is the surface opposite to the first main surface and faces the second end plate 92. The first main surface has a flow path that guides the first fluid to the first discharge manifold 35 or a flow path that guides the second fluid to the second discharge manifold 37. The folding plate 6 may include a conductive plate (not shown) and a frame body, similar to the separator 3. The flow paths (not shown) are provided on the first and second main surfaces of the frame body.

[0069] The resin forming the frame of the folding plate 6 is an electrically insulating resin. The frame of the folding plate 6 formed from such a resin also functions as a member that electrically insulates between the second end plate 92 and the second current collector plate 42. The resin forming the frame of the folding plate 6 may be formed from a resin that is electrically insulating and has at least one of alkali resistance and heat resistance. For the resin forming the frame of the folding plate 6, refer to the description of the resin forming the frame 32 of the separator 3. The resin forming the frame of the folding plate 6 may be the same as or different from the resin forming the supply / discharge plate 5. Unlike this example, the folding plate 6 may not include a conductive plate and may be formed from a resin.

[0070] In this example, the size of the folding plate 6 when viewed from the stacking direction of the stacked body 2a is the same as the size of the supply / discharge plate 5 when viewed from the stacking direction of the stacked body 2a.

[0071] [Piping] The cell stack 2 includes a distribution system, which includes a pipe 7 and a pump (not shown).

[0072] The piping 7 includes a supply pipe connecting a supply source (not shown) to the cell stack 2, and a discharge pipe connecting the cell stack 2 to a storage tank (not shown). The supply source has a first supply source that stores an electrolyte. In this example, the supply source does not have a second supply source that stores an electrolyte, but may further have a second supply source. The storage tank has a first storage tank that stores the generated oxygen gas and a second storage tank that stores the generated hydrogen gas.

[0073] As shown in FIG. 1 , the supply pipe of this example includes a first supply pipe 71 but does not include a second supply pipe. The first supply pipe 71 carries the electrolytic solution supplied to the anode 22. The first supply pipe 71 passes through a first supply communication hole 911 in the first end plate 91, connecting the first supply source and the first supply communication hole in the supply / discharge plate 5. The second supply pipe carries the electrolytic solution supplied to the cathode 23. The second supply pipe passes through a second supply communication hole (not shown) in the first end plate 91, connecting the second supply source and the second supply communication hole in the supply / discharge plate 5. The second supply communication hole in the first end plate 91 communicates with the second supply communication hole in the supply / discharge plate 5. The second supply pipe is inserted through the second supply communication hole in the first end plate 91. In this example, the connection portion of the first supply pipe 71 with the supply / discharge plate 5 is arranged to extend in a direction perpendicular to the second main surface of the first end plate 91. As described above, because the terminals 411, 421 extend in a direction perpendicular to the extension direction of the piping 7, even if electrolyte leaks from the first supply pipe 71, the leaked electrolyte is unlikely to come into contact with the terminals 411, 421 or the current collector plates 41, 42. Furthermore, because the terminals 411, 421 are unlikely to get in the way when connecting the first supply pipe 71 to the supply / discharge plate 5, the work of connecting the first supply pipe 71 to the supply / discharge plate 5 is easy. The second supply pipe passes through the second supply communication hole in the first end plate 91 to connect the second supply source to the second supply communication hole in the supply / discharge plate 5. The second supply communication hole in the first end plate 91 communicates with the second supply communication hole in the supply / discharge plate 5. In this example, the separator 3 does not have a second supply manifold, and the supply / discharge plate 5 does not have a second supply communication hole. Therefore, the first end plate 91 does not have a second supply communication hole. However, if the separator 3 has a second supply manifold and the supply / discharge plate 5 has a second supply passage, the supply pipe may have a second supply pipe.

[0074] The discharge pipes include a first discharge pipe 72 and a second discharge pipe 73. For convenience of explanation, FIG. 2 shows the first discharge pipe 72 and the second discharge pipe 73 arranged in parallel in the vertical direction, but the first discharge pipe 72 and the second discharge pipe 73 are actually arranged in parallel in the depth direction of the paper of FIG. 2 as shown in FIG. 1. The first fluid flows through the first discharge pipe 72. The first discharge pipe 72 passes through a first discharge communication hole 912 in the first end plate 91 shown in FIG. 1 to connect the first discharge communication hole in the supply / discharge plate 5 and the first storage tank. The second discharge pipe 73 passes through a second discharge communication hole 913 in the first end plate 91 to connect the second discharge communication hole in the supply / discharge plate 5 and the second storage tank. In this example, the connection points of first discharge pipe 72 and second discharge pipe 73 with supply / discharge plate 5 are arranged to extend in a direction perpendicular to the second main surface of first end plate 91. Therefore, even if electrolyte leaks from first discharge pipe 72 or second discharge pipe 73, the leaked electrolyte is unlikely to come into contact with terminal portions 411, 421 or current collector plates 41, 42. Furthermore, when connecting first discharge pipe 72 and second discharge pipe 73 to supply / discharge plate 5, terminal portions 411, 421 are unlikely to get in the way, making it easy to connect first discharge pipe 72 and second discharge pipe 73 to supply / discharge plate 5.

[0075] The connection points of the first supply pipe 71, the first discharge pipe 72, and the second discharge pipe 73 with the supply / discharge plate 5 may be formed as cylindrical portions that are integrated into the supply / discharge plate 5 in advance. In a structure in which separately prepared piping is connected to this cylindrical portion, it is easy for an operator to handle long piping, and the connection work is therefore easy.

[0076] The pump pressure-feeds the electrolytic solution to the plurality of electrolytic cells 20. The pump is provided midway along the first supply pipe 71.

[0077] [First End Plate / Second End Plate] The first end plate 91 and the second end plate 92 sandwich the first current collector plate 41 and the second current collector plate 42 from the outside of the first current collector plate 41 and the second current collector plate 42. The first end plate 91 and the second end plate 92 are made of metal. The first end plate 91 and the second end plate 92 made of metal have higher rigidity than end plates made of resin. This makes it easier to maintain the fastened state of the laminate 2a over a long period of time. The metal used to form the first end plate 91 and the second end plate 92 is, for example, steel or nickel. The steel may be any of various types, such as stainless steel or carbon steel.

[0078] The size of the first end plate 91 and the second end plate 92 when viewed from the stacked direction of the stack 2a is larger than the size of the stack 2a when viewed from the stacked direction. That is, the above sizes of the first end plate 91 and the second end plate 92 are larger than the size of the supply / discharge plate 5 and the folding plate 6 when viewed from the stacked direction of the stack 2a. The above size of the first end plate 91 is the same as the above size of the second end plate 92. The second end plate 92 is the same as the first end plate 91 except that it does not have the first supply communication hole 911, the first discharge communication hole 912, and the second discharge communication hole 913, which will be described later. The following description will focus on the first end plate 91.

[0079] As shown in FIG. 5 , the first end plate 91 has a first portion 91a and a second portion 91b. FIG. 5 shows the second main surface of the first end plate 91. The second main surface is the surface opposite to the first main surface. The first main surface is the surface facing the laminate 2a. The first portion 91a is a portion overlapping the laminate 2a. The second portion 91b is a portion disposed outside the first portion 91a. The first portion 91a is a portion inside a first virtual line L1. The second portion 91b is a frame-shaped portion between the first virtual line L1 and the second virtual line L2. For ease of explanation, in FIG. 5 , the two-dot chain line representing the first virtual line L1 is shown smaller than the inner peripheral contour of the first rib 917 to distinguish it from the inner peripheral contour of the first rib 917, which will be described later. In Figure 5, for the sake of convenience, the two-dot chain line indicating the second virtual line L2 is shown larger than the outer peripheral contour line of the first end plate 91 in order to distinguish it from the outer peripheral contour line of the first end plate 91.

[0080] As shown in FIG. 1 , the first end plate 91 of this example has a first supply communication hole 911, a first discharge communication hole 912, and a second discharge communication hole 913. The first supply communication hole 911, the first discharge communication hole 912, and the second discharge communication hole 913 penetrate the first main surface and the second main surface of the first end plate 91. The first supply communication hole 911 communicates with the first supply communication hole of the supply / discharge plate 5. The first supply pipe 71 shown in FIG. 2 is inserted through the first supply communication hole 911. The first discharge communication hole 912 communicates with the first discharge communication hole of the supply / discharge plate 5. The first discharge pipe 72 is inserted through the first discharge communication hole 912. The second discharge communication hole 913 communicates with the second discharge communication hole of the supply / discharge plate 5. The second discharge pipe 73 is inserted into the second discharge communication hole 913 .

[0081] 5, the first end plate 91 of this example has a plurality of through holes 915. Each of the rods 94 shown in FIG. 1 is inserted through each of the through holes 915. In this example, each of the through holes 915 is provided in the second portion 91b.

[0082] As shown in FIGS. 1 and 5 , the first end plate 91 of this example has a first rib 917 and a second rib 918. The first rib 917 is annularly arranged along the outer periphery of the second main surface of the second portion 91b shown in FIG. 5 . Each through-hole 915 is formed in the first rib 917. The second rib 918 is arranged in a lattice pattern to connect the inner peripheries of the first ribs 917. The second rib 918 is arranged on the second main surface of the first portion 91a. The second rib 918 of this example is arranged in a square lattice pattern. That is, the second rib 918 is composed of multiple horizontal ribs along the first side 321 of the frame 32 shown in FIG. 4 and multiple vertical ribs along the third side 323 of the frame 32 shown in FIG. 4 . The horizontal ribs of the second rib 918 connect the left and right vertical ribs of the first rib 917 to each other. The vertical ribs of the second rib 918 connect the upper and lower horizontal ribs of the first rib 917. The number of vertical ribs and horizontal ribs of the second rib 918 is not particularly limited and can be selected as appropriate. In this example, there are two vertical ribs and two horizontal ribs. The first end plate 91 has the first rib 917 and the second rib 918, which provides higher mechanical strength than an end plate without the first rib 917 and the second rib 918. A recess is formed between the first rib 917 and the second rib 918. The thickness of the portion of the first end plate 91 where the recess is formed is thinner than the thickness of the portions of the first rib 917 and the second rib 918. Therefore, the weight of the first end plate 91 can be reduced compared to a first end plate 91 without a recess and having the same thickness as the first rib 917 and the second rib 918.

[0083] The second ribs 918 are arranged more densely in the center of the first end plate 91 than on the periphery. "Arranged more densely in the center than on the periphery" means that the spacing between the lattices in the center is narrower than when the same number of lattices are arranged at equal intervals. "Narrow spacing between the lattices in the center" means that at least one of the first spacing and the second spacing is narrow. The first spacing is the spacing along the first side 321 of the frame 32 shown in FIG. 4. The first spacing is the spacing along the left and right in FIG. 5. The first spacing is the spacing between the vertical ribs. The second spacing is the spacing along the third side 323 of the frame 32 shown in FIG. 4. The second spacing is the spacing along the top and bottom in FIGS. 1 and 5. The second spacing is the spacing between the horizontal ribs. That is, the center being denser than the periphery means that at least one of the following conditions is satisfied: the vertical ribs of the central unit frame constituting the lattice of the second ribs 918 are shorter than the vertical ribs of the peripheral unit frames constituting the lattice; and the horizontal ribs of the central unit frame constituting the lattice are shorter than the horizontal ribs of the peripheral unit frames constituting the lattice. Because the rods 94 are disposed on the outer side of the laminate 2a, as described below, the center, located farthest from the rods 94, is most susceptible to deflection due to thermal expansion and contraction of the laminate 2a, as described below. By arranging the center more densely than the periphery, the center has high mechanical strength. Therefore, the deflection is more likely to be reduced compared to when the second ribs 918 are equally spaced with the same number of lattices. In this example, the second ribs 918 have narrow first and second spacings. Therefore, the deflection is even more likely to be reduced.

[0084] [Clamping Mechanism] The clamping mechanism 93 clamps the first end plate 91 and the second end plate 92 in a direction that brings them closer to each other. The clamping mechanism 93 clamps the first end plate 91 and the second end plate 92 together, thereby maintaining the stacked state of the electrolysis cells 20. The clamping mechanism 93 of this example has a plurality of rods 94, a plurality of first nuts 951, a plurality of second nuts 952, and a plurality of elastic members 96. Unlike this example, the clamping mechanism 93 may be composed of a clamp and an elastic member.

[0085] (Rods) Each rod 94 penetrates the first end plate 91 and the second end plate 92. Each rod 94 is inserted through a through-hole 915 in the first end plate 91 and a through-hole in the second end plate 92 (not shown). Each rod 94 penetrates a first rib 917 in the second portion 91b of the first end plate 91 and a first rib in the second portion of the second end plate 92 (not shown). That is, in this example, each rod 94 does not penetrate the stack 2a, the first current collector plate 41, the second current collector plate 42, the supply / discharge plate 5, or the folding plate 6, but is disposed outside the stack 2a, the first current collector plate 41, the second current collector plate 42, the supply / discharge plate 5, and the folding plate 6. As described above, the seal groove 39 is provided near the outer peripheral edge 32e of the frame 32. Each rod 94 is disposed outside the stack 2a, and thus is disposed near the seal groove 39. Therefore, the tightening mechanism 93 can easily compress the multiple frames 32 effectively so that the seal member arranged in the seal groove 39 is effectively compressed. This makes it difficult for the electrolyte to leak outside the stack 2a. The number of rods 94 is not particularly limited. In this example, there are 14 rods 94. Each rod 94 is made of metal. The metal forming each rod 94 is, for example, steel or titanium. The steel may be any of various types such as stainless steel.

[0086] (First Nut / Second Nut) As shown in Figures 1 and 2, each first nut 951 is attached to the first end of each rod 94 so as to face the second main surface of the first end plate 91. As shown in Figure 2, each second nut 952 is attached to the second end of each rod 94 so as to face the second main surface of the second end plate 92. By tightening the first nut 951 and the second nut 952, the gap between the first end plate 91 and the second end plate 92 is narrowed.

[0087] (Elastic Member) Each elastic member 96 presses the first end plate 91 toward the second end plate 92. The temperature of the electrolyte increases during operation of the hydrogen production device 1. That is, the temperature difference between the electrolyte when the hydrogen production device 1 is stopped and when it is operating increases. As described above, the stack 2a includes multiple frames 32 formed of resin. The thermal expansion coefficient of resin is often higher than that of metals and ceramics. Therefore, the large temperature difference tends to increase the thermal expansion and contraction of the stack 2a. The elastic members 96 easily absorb this thermal expansion and contraction. Although resin has relatively low strength, the elastic members 96 easily absorb this thermal expansion and contraction, which reduces damage to the frame 32 due to the thermal expansion and contraction. Furthermore, the elastic members 96 easily absorb the thermal expansion and contraction, which tends to maintain the compression of the seal members arranged in the seal grooves 39, thereby preventing the electrolyte from leaking outside the stack 2a due to the thermal contraction. Therefore, the hydrogen production device 1 can be used for a long period of time. Each elastic member 96 is provided on the outer periphery of each rod 94, between the first nut 951 and the second main surface of the first end plate 91. The elastic member 96 is, for example, a coil spring or a disc spring. In this example, the elastic member 96 is a coil spring. Each elastic member 96 is made of metal. The metal forming each elastic member 96 is, for example, steel or titanium. The steel may be any of various steels, such as stainless steel, silicon chromium steel, or carbon steel.

[0088] [Electrolyte] The electrolyte is an alkaline aqueous solution. The alkaline aqueous solution may be, for example, potassium hydroxide (KOH) or sodium bicarbonate (NaHCO ３) dissolved in water. When the electrolyte is an alkaline aqueous solution, the electrolysis of water is promoted compared to when the fluid supplied to the electrolytic cell 20 is pure water. The concentration of the electrolyte in the alkaline aqueous solution is, for example, 0.1 mass% or more and 10 mass% or less, when the entire alkaline aqueous solution is taken as 100 mass%. The concentration of the electrolyte in the alkaline aqueous solution may be 0.5 mass% or more and 8 mass% or less, or 1.0 mass% or more and 6.0 mass% or less. The pH value of the alkaline aqueous solution is, for example, 8 or more and 15 or less. The pH value of the alkaline aqueous solution may be 10 or more and 14.3 or less. The electrical conductivity of the alkaline aqueous solution is, for example, 0.003 mS / cm or more and 500 mS / cm or less. The electrical conductivity of the alkaline aqueous solution may be 0.01 mS / cm or more and 400 mS / cm or less, or 0.02 mS / cm or more and 300 mS / cm or less.

[0089] [Electrolysis] An electrolyte is supplied to each anode 22 through the first supply pipe 71. In this example, no electrolyte is supplied to each cathode 23 from the first supply pipe 71. Water moves from each anode 22 side to each cathode 23 through the anion exchange membrane 21. When a voltage is applied between the first current collector plate 41 and the second current collector plate 42 by a power source (not shown), the following electrochemical reaction occurs: Anode: 4OH － →2H ２ O+O ２ +4e － Cathode: 4H ２ O+4e － →2H ２ +4OH －

[0090] At each anode 22, hydroxide ions (OH －) generates water and oxygen and releases electrons. At each cathode 23, water and electrons combine to generate hydrogen and hydroxide ions. The generated hydroxide ions pass through the anion exchange membrane 21 and move from the cathode 23 to the anode 22. Oxygen gas generated at the anode 22 is discharged from the cell stack 2 through the first discharge pipe 72. Hydrogen gas generated at the cathode 23 is discharged from the cell stack 2 through the second discharge pipe 73. The fluid discharged from the first discharge pipe 72 may contain water generated at the anode 22 and unreacted electrolyte solution supplied to the anode 22. The fluid discharged from the second discharge pipe 73 may contain unreacted water that moved to the cathode 23.

[0091] Unlike this example, the cell stack 2 may be any one of the following forms (A) to (C): (A) No supply / discharge plate 5 and no turning-back plate 6. (B) A supply / discharge plate 5 is provided, but no turning-back plate 6 is provided. (C) A supply / discharge plate 5 is not provided, but a turning-back plate 6 is provided.

[0092] In the case of the above-described configuration (A), the separator 3 at the end adjacent to the first current collector plate 41 (hereinafter referred to as the first separator 3) also serves as a supply / discharge plate, and the separator 3 at the end adjacent to the second current collector plate 42 (hereinafter referred to as the second separator 3) also serves as a folding plate. The piping 7 is directly connected to the frame 32 of the first separator 3. That is, each of the pipes 71, 72, and 73 may be directly connected to the frame 32 of the first separator 3 so that the inside of the first supply pipe 71 communicates with the first supply manifold 33, the inside of the first discharge pipe 72 communicates with the first discharge manifold 35, and the inside of the second discharge pipe 73 communicates with the second discharge manifold 37. The pipes 71, 72, and 73 may be welded to the frame 32 using, for example, an organic solvent. The second separator 3 has a flow path that prevents the fluid supplied to the cell stack 2 from flowing out of the cell stack 2 and turns back toward the first end plate 91. Between the first end plate 91 and the first current collector plate 41, and between the second end plate 92 and the second current collector plate 42, an insulating material that electrically insulates the first end plate 91 from the first current collector plate 41 and the second end plate 92 from the second current collector plate 42 may be provided.

[0093] In the case of the above-mentioned form (B), the second separator 3 also serves as a folding plate. The second separator 3 prevents the fluid supplied to the cell stack 2 from flowing out of the cell stack 2, and has a flow path that folds back toward the first end plate 91. The above-mentioned insulating material may be provided between the second end plate 92 and the second current collector plate 42.

[0094] In the case of the above-mentioned form (C), the first separator 3 also serves as a supply / discharge plate. The pipe 7 is directly connected to the frame 32 of the first separator 3. The above-mentioned insulating material may be provided between the first end plate 91 and the first current collector plate 41.

[0095] REFERENCE SIGNS LIST 1 Hydrogen production device 2 Cell stack 2a Laminated body 20 Electrolysis cell 21 Anion exchange membrane 22 Anode 221 Anode catalyst 222 Anode diffusion layer 23 Cathode 231 Cathode catalyst 232 Cathode diffusion layer 3 Separator 31 Conductive plate 32 Frame 32e Outer peripheral edge portion 32i Inner peripheral edge portion 321 First side portion 322 Second side portion 323 Third side portion 324 Fourth side portion 33 First supply manifold 34 First supply slit 35 First discharge manifold 36 First discharge slit 37 Second discharge manifold 38 Second discharge slit 39 Seal groove 41 First current collector plate 411 Terminal portion 42 Second current collector plate 421 Terminal portion 5 Supply and discharge plate 6 Folding plate 7 Piping 71 First supply pipe, 72 First discharge pipe, 73 Second discharge pipe 91 First end plate 91a First portion, 91b Second portion 911 First supply communication hole 912 First discharge communication hole 913 Second discharge communication hole 915 Through hole 917 First rib 918 Second rib 92 Second end plate 93 Fastening mechanism 94 Rod 951 First nut 952 Second nut 96 Elastic member L1 First imaginary line, L2 Second imaginary line

Claims

1. A cell stack provided in a hydrogen production device, comprising: a stack having a plurality of electrolysis cells; a first end plate and a second end plate arranged on either side of the stack; and a clamping mechanism that clamps the first end plate and the second end plate in a direction toward each other, wherein the clamping mechanism has an elastic member that presses the first end plate toward the second end plate, each of the plurality of electrolysis cells having an assembly of an anode, an anion exchange membrane, and a cathode, and separators arranged on either side of the assembly, wherein the separator has a conductive plate and a frame that supports the outer peripheral edge of the conductive plate, and the frame is made of resin.

2. A cell stack as described in claim 1, wherein the tightening mechanism has a plurality of rods passing through the first end plate and the second end plate, and a first nut attached to a first end of each of the plurality of rods, and the elastic member is arranged on the outer periphery of each of the plurality of rods between the first end plate and the first nut.

3. A cell stack as described in claim 2, wherein the first end plate and the second end plate have a first portion overlapping the stack and a second portion arranged on the outer periphery of the first portion, and each of the plurality of rods penetrates the second portion.

4. A cell stack as described in claim 3, wherein the first end plate and the second end plate have a first rib arranged annularly along the outer periphery of the surface opposite the stack in the second portion, and each of the plurality of rods passes through the first rib.

5. A cell stack according to claim 4, wherein the first end plate and the second end plate have second ribs arranged in a lattice pattern so as to connect the inner peripheral surfaces of the first ribs.

6. The cell stack according to claim 5, wherein the second ribs are arranged more densely in the center of the surface than in the periphery.

7. A cell stack according to any one of claims 1 to 6, wherein the number of separators is 15 or more.

8. A cell stack according to any one of claims 1 to 7, wherein the elastic member is a coil spring.

9. A cell stack according to any one of claims 1 to 8, comprising: a first current collecting plate arranged between the stack and the first end plate; a second current collecting plate arranged between the stack and the second end plate; a supply and discharge plate arranged between the first current collecting plate and the first end plate; and piping connected to the supply and discharge plate, wherein the piping comprises: a supply pipe through which electrolyte supplied to the anode flows; a first discharge pipe through which oxygen gas from the anode flows; and a second discharge pipe through which hydrogen gas from the cathode flows.

10. A cell stack as described in claim 9, wherein the connection points of the supply pipe, the first discharge pipe, and the second discharge pipe with the supply and discharge plate are arranged to extend in a direction perpendicular to the surface of the first end plate opposite the stack.

11. A cell stack as described in claim 9 or claim 10, wherein the first current collector plate and the second current collector plate have terminal portions that protrude from the outer peripheral edge of the laminate, and the terminal portions extend in a direction perpendicular to the direction in which the connection points extend.

12. A cell stack according to any one of claims 1 to 11, wherein the resin is a resin that is alkali-resistant to an electrolyte solution having a pH of 8 or higher.

13. A cell stack according to any one of claims 1 to 12, wherein the resin is heat resistant to temperatures of 80°C or less.

14. A hydrogen production device comprising the cell stack according to any one of claims 1 to 13.

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