Water electrolysis stack

Abstract

The present invention provides a water electrolysis stack capable of suppressing a decrease in sealing performance. The water electrolysis stack is configured by stacking a plurality of water electrolysis cells, and generates a hydrogen water electrolysis stack by supplying water to the water electrolysis cells and applying electric power to the water electrolysis cells, and a sealability-improving stacked member, which is a member that does not introduce water into the stacked water electrolysis cells, is stacked at a predetermined position in the stacked water electrolysis cells.

Description

Technical Field

[0001] The present disclosure relates to a water electrolysis stack having stacked water electrolysis cells. Background Art

[0002] Patent Document 1 discloses a high-pressure-resistant structure of a sealing member at a planar end portion of a water electrolysis cell in order to increase the pressure of hydrogen generated by water electrolysis and supply it within the water electrolysis stack.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-123906

[0004] In a water electrolysis stack, as the internal pressure of the hydrogen electrode rises, Figure 16 As shown, the central portion of the multiple water electrolysis chambers arranged between the end plates swells, and the water electrolysis chambers located closest to the end plates bend and expand, deforming as shown by the dotted circles. This may reduce the sealing performance of the sealing members arranged at these ends. This reduction in sealing performance may lead to insufficient hydrogen pressure increase and hydrogen leakage. Summary of the Invention

[0005] In view of the above-mentioned problems, an object of the present disclosure is to provide a water electrolysis stack capable of suppressing a decrease in sealing performance.

[0006] The present application discloses a water electrolysis stack, which is composed of a plurality of stacked water electrolysis chambers. The water electrolysis stack generates hydrogen by supplying water to the water electrolysis chambers and applying electricity. In particular, stacking components for improving sealing are stacked at specified positions of the stacked water electrolysis chambers. The stacking components for improving sealing are components that do not introduce water into the interior.

[0007] The laminated component for improving sealing can also be constructed to include: a first outer body, which has the same shape as the anode diaphragm possessed by the water electrolysis chamber; a second outer body, which has the same shape as the cathode diaphragm possessed by the water electrolysis chamber; a core member, which is arranged between the first outer body and the second outer body; and a frame, which is arranged between the first outer body and the second outer body and bonds the first outer body and the second outer body.

[0008] The device may be configured to include a communication hole that connects the space between the first exterior body and the second exterior body to the outside.

[0009] The communicating hole may be provided in at least one of the first exterior body or the second exterior body.

[0010] The communicating hole may be provided in the frame.

[0011] The communicating hole may be formed between the first external housing and the frame, or between the second external housing and the frame.

[0012] The core member may be constructed from the same material as the cathode gas diffusion layer of the water electrolysis cell.

[0013] The sealing performance improving laminate member may be disposed at an end portion of the laminate body formed by the water electrolysis stack.

[0014] The sealing performance-enhancing laminated member may be a plate-shaped member that is less likely to bend than the water electrolysis cell.

[0015] The sealing-improving laminated member may be disposed between a plurality of water electrolysis stacks.

[0016] According to the present disclosure, the sealing-improving laminated member can reduce the number of water electrolysis cells that are significantly deformed, thereby suppressing a decrease in the sealing performance within the water electrolysis stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a plan view of the water electrolysis chamber 10 .

[0018] Figure 2 This is a schematic diagram illustrating the layer structure in the water electrolysis region 10 a of the water electrolysis cell 10 .

[0019] Figure 3 This is a schematic diagram illustrating the layer structure of the oxygen electrode lead-out side distribution region 10 d and the oxygen electrode lead-out region 10 e of the water electrolysis cell 10 .

[0020] Figure 4 This is a schematic diagram illustrating the structure of the water electrolysis stack 30 .

[0021] Figure 5 This is a diagram illustrating the stacked structure of the water electrolysis cells 10 in the water electrolysis stack 30 .

[0022] Figure 6 This is another diagram illustrating the stacked structure of the water electrolysis cells 10 in the water electrolysis stack 30 .

[0023] Figure 7 This is a schematic diagram illustrating the structure of the water electrolysis stack 40 .

[0024] Figure 8 This is a plan view of the sealing performance improving laminate member 41 .

[0025] Figure 9 It is a cross-sectional view of the sealing performance improving laminated member 41 .

[0026] Figure 10 This is another cross-sectional view of the sealing performance improving laminated member 41 .

[0027] Figure 11 This is a diagram illustrating a first modification of the sealing performance-enhancing laminate member 41 .

[0028] Figure 12 This is a diagram illustrating a second modification of the sealing performance enhancing laminate member 41 .

[0029] Figure 13 This is a diagram illustrating a third modification of the sealing performance improving laminate member 41 .

[0030] Figure 14 This is a schematic diagram illustrating the structure of the water electrolysis stack 50 .

[0031] Figure 15 This is a plan view of the sealing performance improving laminated member 51 .

[0032] Figure 16 This is a diagram illustrating the curvature of the water electrolysis chamber in the water electrolysis stack.

[0033] Captions

[0034] 10…water electrolysis chamber; 10a…water electrolysis region; 10b…oxygen electrode inlet region; 10c…oxygen electrode inlet side distribution region; 10d…oxygen electrode outlet side distribution region; 10e…oxygen electrode outlet region; 11…solid polymer electrolyte membrane (electrolyte membrane); 12…anode catalyst layer (catalyst layer); 13…anode gas diffusion layer (oxygen electrode gas diffusion layer); 14…anode diaphragm (oxygen electrode diaphragm); 14a…supply flow path; 14d…oxygen electrode side Inlet manifold (oxygen electrode inlet hole); 14e…oxygen electrode side outlet manifold (oxygen electrode outlet hole); 14f…hydrogen electrode side outlet manifold (hydrogen electrode outlet hole); 14g…narrowing portion (structure for generating turbulence); 15…cathode catalyst layer (catalyst layer); 16…cathode gas diffusion layer (hydrogen electrode gas diffusion layer); 17…cathode diaphragm (hydrogen electrode diaphragm); 18…frame; 30, 40, 50…water electrolysis stack; 41, 51…laminated components for improving sealing. DETAILED DESCRIPTION

[0035] 1. Basic structure of water electrolysis stack

[0036] The water electrolysis stack disclosed herein is characterized by being equipped with a sealing-enhancing laminated component. First, the basic structure of a water electrolysis stack equipped with the sealing-enhancing laminated component will be described. The sealing-enhancing laminated component and the water electrolysis stack equipped with the sealing-enhancing laminated component will then be described.

[0037] 1.1. Water electrolysis chamber

[0038] In the water electrolysis stack, a plurality of water electrolysis chambers are stacked to form the main part. Figure 1, there is shown a diagram illustrating the structure of a water electrolysis cell 10 according to one embodiment. The water electrolysis cell 10 is a unit element for decomposing pure water into hydrogen and oxygen, and a water electrolysis stack is constructed by stacking a plurality of such water electrolysis cells 10 . Figure 1 This is a top view of the water electrolysis chamber 10 (the stacking direction of the plurality of water electrolysis chambers 10 is the depth / front direction of the paper). Figure 1 In order to illustrate the internal structure of the water electrolysis cell 10, a portion of the internal structure (particularly the oxygen electrode side) is indicated by a dotted line.

[0039] The water electrolysis in the water electrolysis chamber 10 is well known, and its outline is as follows.

[0040] Pure water flows from the oxygen electrode inlet port (oxygen electrode side inlet manifold) 14d into the oxygen electrode inlet region 10b. After the pure water is evenly distributed in the oxygen electrode inlet side distribution region 10c, it reaches the water electrolysis region 10a, where water electrolysis occurs. However, water electrolysis can also occur in the oxygen electrode inlet side distribution region 10c.

[0041] In the water electrolysis zone 10a, a portion of the pure water is decomposed into oxygen and hydrogen by the water electrolysis membrane electrode assembly (described later), and these are discharged through their respective flow paths. The generated oxygen and remaining pure water are collected through the oxygen electrode outlet distribution zone 10d and the oxygen electrode outlet flow path 10e, and then discharged from the oxygen electrode outlet port (oxygen electrode side outlet manifold) 14e.

[0042] Meanwhile, the generated hydrogen moves to the electrode (hydrogen electrode) on the opposite side of the electrode (oxygen electrode) through which pure water flows, across the water electrolysis membrane electrode assembly, and is discharged from the hydrogen electrode outlet port (hydrogen electrode side outlet manifold) 14f via another flow path (not shown). Both the oxygen electrode and the hydrogen electrode are located within the water electrolysis chamber 10, but are separated by a sealing member (not shown) outside the water electrolysis region 10a to prevent the generated hydrogen and oxygen from mixing, thereby forming separate flow paths.

[0043] Furthermore, similar to the unit cells of the fuel cell, another pair of manifolds may be provided for flowing the fluid between adjacent water electrolysis cells. In this case, it is preferable to flow the hydrogen generated there.

[0044] Next, the structure of the water electrolysis cell 10 will be described. Figure 2 yes Figure 1 A portion of the AA cross section of FIG. 1 is a diagram illustrating the layer structure of the water electrolysis region 10 a in the water electrolysis chamber 10 where water electrolysis is mainly performed. Figure 3 yes Figure 1The BB cross section shows the layer structure of a portion of the oxygen electrode lead-out hole (oxygen electrode side outlet manifold) 14e, the oxygen electrode lead-out region 10e, the oxygen electrode lead-out side distribution region 10d, and a portion of the water electrolysis region 10a.

[0045] The water electrolysis cell 10 is composed of a plurality of layers, with a solid polymer electrolyte membrane 11 sandwiched therebetween. One side serves as an oxygen electrode (anode), and the other side serves as a hydrogen electrode (cathode).

[0046] In the water electrolysis region 10a, as Figure 2 As shown, the anode comprises an anode catalyst layer 12, an anode gas diffusion layer 13, and an anode separator 14, stacked in order from the solid polymer electrolyte membrane 11 side. Meanwhile, the cathode comprises a cathode catalyst layer 15, a cathode gas diffusion layer 16, and a cathode separator 17, stacked in order from the solid polymer electrolyte membrane 11 side. Here, the water electrolysis membrane electrode assembly refers to a stack of the solid polymer electrolyte membrane 11, the anode catalyst layer 12 disposed on the anode side of the solid polymer electrolyte membrane 11, and the cathode catalyst layer 15 disposed on the cathode side of the solid polymer electrolyte membrane 11. The thickness of the water electrolysis membrane electrode assembly is typically about 0.4 mm, and the thickness of the water electrolysis cell 10 in the water electrolysis region 10a is typically about 1.3 mm.

[0047] At both ends of the water electrolysis region 10a of the water electrolysis chamber 10, as shown in FIG. Figure 3 As shown, a frame 18 is provided.

[0048] First, the morphology of each layer will be described, and then the layer structure in each region will be described.

[0049] 1.1.1. Morphology of each layer

[0050] The layers included in the water electrolysis cell 10 have the following forms, for example. However, the water electrolysis cell of the present disclosure is not limited to this form.

[0051] [Solid Polymer Electrolyte Membrane]

[0052] The solid polymer electrolyte membrane 11 is one form of a proton-conductive electrolyte membrane. In this embodiment, the material (electrolyte) constituting the solid polymer electrolyte membrane 11 is a solid polymer material, such as a proton-conductive ion exchange membrane formed from a fluorine-based resin or hydrocarbon resin. It exhibits excellent proton conductivity (electrical conductivity) in a wet state. More specifically, a membrane formed from perfluorosulfonic acid (Nafion, a registered trademark), a perfluoroelectrolyte, can be used.

[0053] The thickness of the solid polymer electrolyte membrane 11 is not particularly limited, but is 200 μm or less, preferably 100 μm or less, and more preferably 30 μm or less.

[0054] [Anode catalyst layer]

[0055] The anode catalyst layer (oxygen electrode catalyst layer) 12 is a catalyst layer containing at least one catalyst including a noble metal catalyst such as Pt, Ru, Ir, and their oxides. More specifically, the catalyst can be Pt, iridium oxide, ruthenium oxide, iridium ruthenium oxide, or a mixture thereof.

[0056] Examples of the iridium oxide include iridium oxide (IrO 2 , IrO 3 ), iridium tin oxide, and iridium zirconium oxide.

[0057] Examples of the ruthenium oxide include ruthenium oxide (RuO 2 , Ru 2 O 3 ), ruthenium tantalum oxide, ruthenium zirconium oxide, ruthenium titanium oxide, and ruthenium titanium cerium oxide.

[0058] Examples of the iridium ruthenium oxide include iridium ruthenium cobalt oxide, iridium ruthenium tin oxide, iridium ruthenium iron oxide, and iridium ruthenium nickel oxide.

[0059] Here, the anode catalyst layer 12 may also contain an ionomer. Inclusion of the ionomer not only improves coating properties but also facilitates the permeation of water supplied during water decomposition due to its hydrophilicity. Examples of the ionomer include ionomers containing perfluorinated electrolytes, which are electrolytes used in solid polymer electrolyte membranes.

[0060] [Anode gas diffusion layer]

[0061] The anode gas diffusion layer 13 is a gas diffusion layer disposed on the anode side. While a known gas diffusion layer can be used, it is formed of a member having gas permeability and electrical conductivity. Specifically, examples include porous conductive members formed of sintered bodies such as metal fibers (e.g., titanium fibers) or metal particles (titanium particles).

[0062] [Anode diaphragm]

[0063] The anode separator 14 is a member (diaphragm) having a flow path (water supply flow path) 14a through which pure water, decomposed oxygen, and residual water supplied to the anode gas diffusion layer 13 flow. In the present embodiment, the anode separator 14 is a plate-like member formed into a corrugated shape with repeated projections and depressions in the water electrolysis region 10a. The recessed portions 14c are arranged so as to contact the anode gas diffusion layer 13, thereby forming the water supply flow path 14a between the anode gas diffusion layer 13 and the convex portions 14b.

[0064] The anode separator 14 can be produced by, for example, stamping a titanium thin film. The thickness thereof is typically 0.1 mm to 0.2 mm, and the height of the concavities and convexities is typically about 0.5 mm.

[0065] In addition, if Figure 1 As described above, the anode diaphragm 14 is provided with an oxygen electrode side inlet manifold 14d serving as an inlet for pure water, an oxygen electrode side outlet manifold 14e serving as an outlet for the generated oxygen and residual water, and a hydrogen electrode side outlet manifold 14f serving as an outlet for the generated hydrogen and accompanying water.

[0066] And, as Figure 3 As shown, in the oxygen electrode lead-out region 10 e of the anode separator 14 of the present embodiment, a constricted portion 14 g is provided so as to bulge toward the cathode separator 17 side.

[0067] In the present embodiment, grooves may be provided on the surface of the anode separator 14 on the side facing the cathode separator 17 in the oxygen electrode lead-out side distribution region 10 d and the oxygen electrode lead-out region 10 e connected thereto.

[0068] Furthermore, a conductive layer may be provided on the front and back surfaces of the anode separator 14 at locations corresponding to the water electrolysis region 10a to reduce electrical contact resistance. The conductive layer may be made of any material as long as it is conductive, and an example thereof is platinum.

[0069] [Cathode catalyst layer]

[0070] The cathode catalyst layer 15 is a catalyst layer containing a catalyst. The catalyst contained in the cathode catalyst layer 15 can be a known catalyst, for example, platinum, platinum-coated titanium, platinum-supported carbon, palladium-supported carbon, cobalt glyoxime, nickel glyoxime, etc.

[0071] Here, the cathode catalyst layer 15 may also contain an ionomer. By containing an ionomer, coating properties can be improved. Examples of the ionomer to be contained include ionomers composed of perfluoroelectrolytes used as electrolytes for solid polymer electrolyte membranes.

[0072] [Cathode gas diffusion layer]

[0073] The cathode gas diffusion layer 16 is a gas diffusion layer disposed on the cathode side. Known gas diffusion layers can be used, but are made of a gas-permeable and conductive material. Specifically, porous materials such as carbon cloth and carbon paper can be used.

[0074] [Cathode diaphragm]

[0075] The cathode separator 17 is a member having a flow path 17a through which hydrogen generated by reducing hydrogen ions and water (accompanying water) accompanying the hydrogen ions as they pass through the solid polymer electrolyte membrane 11 reach. In this embodiment, the cathode separator 17 is a member formed by forming a plate-like member into a corrugated shape with repeated projections and depressions in the water electrolysis region 10a. The concave portions 17c are arranged so as to contact the cathode gas diffusion layer 16, thereby forming the flow path 17a for discharging hydrogen between the cathode gas diffusion layer 16 and the convex portions 17b.

[0076] The cathode separator 17 can be produced by, for example, stamping a titanium thin film. The thickness thereof is typically 0.1 mm to 0.2 mm, and the height of the concavities and convexities is typically about 0.5 mm.

[0077] In addition, in the cathode diaphragm 17, as Figure 1 As described above, there are provided an oxygen electrode side inlet manifold (not shown) overlapping with the above-mentioned oxygen electrode side inlet manifold 14d, an oxygen electrode side outlet manifold (not shown) overlapping with the above-mentioned oxygen electrode side outlet manifold 14e, and a hydrogen electrode side outlet manifold (not shown) overlapping with the above-mentioned hydrogen electrode side outlet manifold 14f.

[0078] In order to reduce electrical contact resistance, a conductive layer may be provided on the front and back surfaces of the cathode separator 17 at locations corresponding to the water electrolysis region 10a. The conductive layer may be made of any material as long as it has electrical conductivity, and an example thereof is platinum.

[0079] [frame]

[0080] The frame 18 functions as a sealing member disposed between the anode separator 14 and the cathode separator 17 on the outer periphery of the water electrolysis cell 10 to seal the inside thereof and to separate the oxygen electrode side from the hydrogen electrode side to form a necessary flow path.

[0081] Therefore, the frame 18 is arranged to surround the water electrolysis region 10a, the oxygen electrode introduction region 10b, the oxygen electrode introduction side dispersion region 10c, the oxygen electrode outlet side dispersion region 10d, and the oxygen electrode outlet region 10e, and is sandwiched between the anode separator 14 and the cathode separator 17.

[0082] For the frame 18, for example, Figure 3 In the cross section of , in order to allow the generated oxygen and residual water to flow from the water supply flow path 14a of the anode diaphragm 14 through the oxygen electrode outlet side distribution area 10d and the oxygen electrode outlet area 10e to the oxygen electrode side outlet manifold 14e, this part is not sealed. Figure 3In the cross section, the frame 18 is sealed to cut off the flow of hydrogen from the flow path 17a of the cathode diaphragm 17 to the oxygen electrode side inlet manifold 14e. In this way, the frame 18 adjusts the contact (sealing) with the anode diaphragm 14 and the cathode diaphragm 17 so that the flow of fluid becomes appropriate.

[0083] The frame 18 is formed of a thermoplastic resin material having electrical insulation and airtightness and a relatively high melting point. Examples of such materials include engineering plastics. Examples of engineering plastics include polyethylene naphthalate resins (PEN), polyphenylene sulfide resins (PPS), and polyphenylene sulfone resins (PPSU).

[0084] The thickness of the frame is not particularly limited, but is preferably 0.05 mm or more and 0.25 mm or less.

[0085] Adhesive is placed on the front and back surfaces of the frame 18 to bond the portion of the anode separator 14 and the portion of the cathode separator 17 that are in contact therewith.

[0086] 1.1.2. Layer structure of the water electrolysis region

[0087] like Figure 2 As shown, the layer structure of the water electrolysis region 10a is as follows: the anode is composed of an anode catalyst layer 12, an anode gas diffusion layer 13, and an anode separator 14 stacked in this order from the solid polymer electrolyte membrane 11 side. On the other hand, the cathode is composed of a cathode catalyst layer 15, a cathode gas diffusion layer 16, and a cathode separator 17 in this order from the solid polymer electrolyte membrane 11 side.

[0088] The anode separator 14 includes a flow path (water supply flow path) 14a through which pure water and decomposed oxygen flow to be supplied to the anode gas diffusion layer 13. In the present embodiment, the anode separator 14 is formed by forming a plate-like member into a corrugated shape with repeated projections and depressions in the water electrolysis region 10a. The recessed portions 14c are arranged so as to contact the anode gas diffusion layer 13, thereby forming the water supply flow path 14a between the anode gas diffusion layer 13 and the convex portions 14b.

[0089] The cathode diaphragm 17 has a flow path 17a through which hydrogen generated by reducing hydrogen ions and water (accompanying water) accompanying the hydrogen ions when they pass through the solid polymer electrolyte membrane 11 arrive. In this embodiment, the cathode diaphragm 17 forms a plate-like component into a wavy shape in the water electrolysis area 10a and repeatedly provides concave and convex parts. The concave part 17c is arranged in a manner that contacts the cathode gas diffusion layer 16, thereby forming a flow path 17a for hydrogen discharge between the cathode gas diffusion layer 16 and the convex part 17b.

[0090] 1.1.3. Structure of other areas

[0091] As other regions, there can be cited the oxygen electrode introduction region 10b, the oxygen electrode introduction side distribution region 10c, the oxygen electrode lead-out side distribution region 10d, the oxygen electrode lead-out region 10e, the hydrogen electrode lead-out side distribution region (not shown), and the hydrogen electrode lead-out region. Figure 1 、 Figure 3 The oxygen electrode lead-out side distribution region 10d and the oxygen electrode lead-out region 10e shown are used as examples for description.

[0092] The oxygen electrode lead-out side distribution region 10d and the oxygen electrode lead-out region 10e are regions through which oxygen generated in the water electrolysis region 10a and residual water pass until being discharged to the oxygen electrode side outlet manifold 14e.

[0093] In the oxygen electrode lead-out side distribution area 10d, according to Figure 3 It can be seen that the end faces of the solid polymer electrolyte membrane 11, the anode catalyst layer 12, the anode gas diffusion layer 13, the cathode catalyst layer 15 and the cathode gas diffusion layer 16 are formed. Here, the end face of the anode gas diffusion layer 13 is formed at a slightly receded position compared to the other end faces. Moreover, the frame 18 is configured in a manner stacked on the anode catalyst layer 12 and extending from the end face of the anode gas diffusion layer 13. The frame 18 is configured to reach the oxygen electrode lead-out region 10e and extend to the oxygen electrode outlet manifold 14e. In addition, in the oxygen electrode lead-out side distribution region 10d, the cathode diaphragm 17 is bent in the thickness direction (the stacking direction of each layer) to contact the surface of the frame 18, thereby sealing the hydrogen electrode side.

[0094] In the oxygen electrode lead-out region 10e, a constricted portion 14g is formed by bending the anode separator 14 close to the frame 18, thereby narrowing the flow path in the thickness direction. However, since the oxygen generated and the residual water need to flow here, a predetermined gap is provided to form a flow path leading to the oxygen electrode-side outlet manifold 14e.

[0095] For the oxygen electrode inlet area 10b and the oxygen electrode inlet side distribution area 10c, the direction of fluid flow is different, but the oxygen electrode inlet area 10b can be considered to be the same as the oxygen electrode outlet area 10e, and the oxygen electrode inlet side distribution area 10c can be considered to be the same as the oxygen electrode outlet side distribution area 10d.

[0096] The hydrogen electrode lead-out side distribution region and the hydrogen electrode lead-out region are regions where a flow path is formed to guide the hydrogen and accompanying water generated on the hydrogen electrode side from the water electrolysis region 10a to the hydrogen side outlet manifold 14f. The structure of these regions can be a form in which the structure of the above-mentioned oxygen electrode lead-out side distribution region 10d and oxygen electrode lead-out region 10e is applied to the hydrogen electrode side.

[0097] 1.1.4. Functions, etc.

[0098] According to the water electrolysis cell 10 , for example, it is possible to function as follows.

[0099] When pure water is supplied from the oxygen electrode side inlet manifold 14d, the pure water reaches the water electrolysis area 10a via the oxygen electrode introduction area 10b and the oxygen electrode introduction side distribution area 10c. In the water electrolysis area 10a, by energizing between the anode and the cathode, the pure water (H2O) supplied from the water supply flow path 14a to the anode (oxygen generating electrode) is decomposed into oxygen, electrons, and protons (H + ). At this time, the protons pass through the solid polymer electrolyte membrane 11 and move toward the cathode catalyst layer 15. On the other hand, the electrons separated in the anode catalyst layer 12 pass through the external circuit and reach the cathode catalyst layer 15. Then, in the cathode catalyst layer 15, the protons receive the electrons to generate hydrogen (H2), which then reaches the cathode gas diffusion layer 16. In addition, the hydrogen generated in the cathode gas diffusion layer 16 is accompanied by water.

[0100] The hydrogen gas and accompanying water present in the cathode gas diffusion layer 16 reach the cathode diaphragm 17, flow in the flow path 17a, pass through the hydrogen electrode lead-out side distribution region and hydrogen electrode lead-out region (not shown), and are discharged from the hydrogen electrode side outlet manifold 14f (hydrogen electrode lead-out hole).

[0101] On the other hand, oxygen generated in the anode catalyst layer 12 and unused residual water return to the anode diaphragm 14, pass through the hydrogen supply flow path 14a, and are discharged from the oxygen electrode outlet manifold 14e through the oxygen electrode outlet side distribution area 10d and the oxygen electrode outlet area 10e.

[0102] 1.2. Water electrolysis stack

[0103] The water electrolysis stack 30 is a component formed by stacking a plurality of (about 50 to 400) of the above-mentioned water electrolysis cells 10. Electricity is supplied to the plurality of water electrolysis cells 10 to generate hydrogen and oxygen. Figure 4 The water electrolysis cell 30 includes a stack casing 31 , an end plate 32 , and a plurality of water electrolysis cells 10 .

[0104] The stack housing 31 is a casing that houses the stacked multiple water electrolysis cells 10 and the force applying member 33. In this embodiment, the stack housing 31 is a quadrilateral tube with one end open and the other closed. A plate-like piece extends along the edge of the opening toward the side opposite the opening, forming a flange 31a.

[0105] The end plate 32 is a plate-shaped member that closes the opening of the stack housing 31 and has manifold connections for oxygen and hydrogen inlet and outlet ports. The end plate 32 is secured to the stack housing 31 using bolts and nuts, such as a portion overlapping the flange 31a of the stack housing 31.

[0106] Furthermore, the stack of multiple water electrolysis cells 10 is held at both ends in the stacking direction by the end plates 32 and the stack housing 31. In this case, the portion of the stack housing disposed at the ends in the stacking direction of the water electrolysis cells also functions as an end plate, thereby holding the stack of multiple water electrolysis cells 10 at both ends in the stacking direction.

[0107] The water electrolysis chamber 10 is as described above. A plurality of such water electrolysis chambers 10 are stacked. Here, in this embodiment, according to Figure 4 It can be seen that the water electrolysis chambers 10 are configured to overlap in the horizontal direction. Figure 1 As shown, the water supply flow paths 14a and the flow paths 17a are arranged in a vertical direction.

[0108] In addition, by overlapping the oxygen electrode side inlet manifolds 14d of each water electrolysis chamber, a flow path for supplying water is formed, by overlapping the oxygen electrode side outlet manifolds 14e, a flow path for discharging oxygen and residual water is formed, and by overlapping the hydrogen electrode side outlet manifolds 14f, a flow path for discharging hydrogen and accompanying water is formed.

[0109] If necessary, a biasing member (not shown) may be provided to press the stack of water electrolysis cells in the stacking direction. The biasing member is housed inside the stack housing 31 and applies a pressing force in the stacking direction to the stack of water electrolysis cells 10. Examples of the biasing member include a Belleville spring.

[0110] 2.2. Laminated structure of water electrolysis chambers

[0111] As described above, the water electrolysis stack 30 is formed by stacking a plurality of water electrolysis cells 10. Figure 5 In FIG. 1 , three of the stacked water electrolysis chambers 10 are extracted to show a cross section of a portion of the water electrolysis region 10a. Figure 6 , three of the stacked water electrolysis cells are extracted to show a cross section of a portion of their end portions (the oxygen electrode lead-out side distribution region 10d and the oxygen electrode lead-out region 10e).

[0112] according to Figure 5 、 Figure 6 It can be seen that when the water electrolysis cells 10 are stacked, the cathode separator 17 of one water electrolysis cell 10 overlaps the anode separator 14 of another water electrolysis cell 10. More specifically, the convex portion 17b of the cathode separator 17 of one water electrolysis cell 10 contacts and overlaps the convex portion 14b of the anode separator 14 of the other water electrolysis cell 10.

[0113] In addition, according to Figure 6As can be seen, at the end portion (in this embodiment, the narrowed portion 14g) of the water electrolysis cell 10, an inter-cell sealing member 33 is disposed between adjacent water electrolysis cells 10. The inter-cell sealing member 33 provides sealing to prevent fluid leakage from the manifolds.

[0114] 2. Water electrolysis stack disclosed herein

[0115] Method 1

[0116] exist Figure 7 2 is a diagram illustrating a water electrolysis stack 40 as an embodiment of the water electrolysis stack according to the present disclosure. Figure 7 Is based on Figure 4 The same perspective diagram. Figure 7 As can be seen, the water electrolysis stack 40 according to embodiment 1 has, in addition to the water electrolysis stack 30, one or more sealing-enhancing stacking members 41 stacked at each end of the stacking direction of the plurality of water electrolysis cells 10. The structure of the water electrolysis stack 40 other than the sealing-enhancing stacking members 41 is considered identical to that of the water electrolysis stack 30, and thus, the same reference numerals are used herein and description thereof will be omitted.

[0117] exist Figures 8 to 10 , there are shown diagrams for explaining the structure of the sealing performance improving laminate member 41 included in this embodiment. Figure 8 This is a plan view of the sealing-enhancing stacking member 41 (seen from the direction of stacking with the water electrolysis cells 10 , which is the direction of depth / front of the paper). Figure 9 is Figure 8 The cross section of the part indicated by CC. Figure 10 is Figure 8 The cross section of the part indicated by DD. Figures 8 to 10 As can be seen, in this embodiment, the sealing-enhancing laminated member 41 has a similar configuration to the aforementioned water electrolysis chamber 10, and its outer shape is substantially the same as that of the water electrolysis chamber 10. However, the sealing-enhancing laminated member 41 is not intended for water electrolysis, and is configured so that the supply water does not flow through it.

[0118] The sealing performance improving laminate member 41 is composed of a plurality of layers and includes a core member 42 , a first exterior panel 43 , a second exterior panel 44 , and a frame 45 .

[0119] 2.1.1. Morphology of each layer

[0120] Each layer included in the sealing performance improving laminate member 41 has the following forms, for example.

[0121] [Core]

[0122] The core member 42 is a plate-shaped member disposed between the first outer casing 43 and the second outer casing 44, and serves as the core of the sealing-enhancing laminated member 41. The material constituting the core member 42 is not particularly limited, as long as it is conductive and has a certain degree of strength and cushioning properties. In this embodiment, the cathode gas diffusion layer 16 is laminated to form a double layer based on these considerations.

[0123] From the viewpoint of electrical conductivity and load transfer, the thickness of the core member 42 is preferably approximately the same as the thickness of the laminated body disposed between the anode separator 14 and the cathode separator 17 in the water electrolysis cell 10 .

[0124] [1st outer body]

[0125] The first outer casing 43 is a plate-like member having the same shape as the aforementioned anode separator 14. Therefore, in this embodiment, the first outer casing 43 is a member formed by repeatedly forming the plate-like member into a corrugated shape in the region 41a where the core member 42 is disposed, with the concave portion 43c disposed so as to contact the core member 42, thereby forming a cavity 43a between the core member 42 and the convex portion 43b.

[0126] The first outer casing 43 , like the anode separator 14 , can be produced by, for example, press-molding a titanium thin film. The thickness can be 0.1 mm to 0.2 mm, and the height of the concavities and convexities can be approximately 0.5 mm.

[0127] Furthermore, the first outer casing 43 is provided with a first hole 43d corresponding to the oxygen electrode side inlet manifold 14d, a second hole 43e corresponding to the oxygen electrode side outlet manifold 14e, and a third hole 43f corresponding to the hydrogen electrode side outlet manifold 14f. After the sealing enhancement stacking member 41 is stacked on the water electrolysis cell 10, these holes overlap with the corresponding manifolds.

[0128] And, as Figure 10 As shown, in this embodiment, the first exterior body 43 is provided with a narrowed portion 43 g so as to protrude toward the frame 45 .

[0129] In addition, in the stacked component 41 for improving sealing, as mentioned above, the intention here is not to perform water electrolysis, so there is no need to supply water to the inside, so there is no area equivalent to the oxygen electrode lead-out side distribution area 10d set in the anode diaphragm 14 and the oxygen electrode lead-out area 10e continuous therewith, so that it is sealed in a manner of contact with the frame 45.

[0130] [Second outer body]

[0131] The second outer casing 44 is a plate-like member having the same shape as the cathode separator 17. Therefore, in this embodiment, the second outer casing 44 is a member formed by repeatedly forming the plate-like member into a corrugated shape in the region 41a where the core member 42 is arranged, with the concave portion 44c arranged so as to contact the core member 42, thereby forming a cavity 44a between the core member 42 and the convex portion 44b.

[0132] The second outer casing 43 , like the anode separator 14 , can be produced by, for example, press-molding a titanium thin film. The thickness can be 0.1 mm to 0.2 mm, and the height of the concavities and convexities can be approximately 0.5 mm.

[0133] In addition, the second outer casing 43 is also provided with a first hole corresponding to the oxygen electrode side inlet manifold 14d, a second hole corresponding to the oxygen electrode side outlet manifold 14e, and a third hole corresponding to the hydrogen electrode side outlet manifold 14f (none of which are shown in the figure). After the sealing improving stacking member 41 and the water electrolysis cell 10 are stacked, these holes overlap with the corresponding manifolds.

[0134] In addition, in the stacked component 41 for improving sealing, as mentioned above, the intention here is not to perform water electrolysis, so there is no need to supply water to the inside, so there is no hydrogen electrode lead-out side distribution area (not shown) set in the cathode diaphragm 17 and the hydrogen electrode lead-out area (not shown) continuous therewith, so that it is sealed in a manner of contact with the frame 45.

[0135] [frame]

[0136] The frame 45 functions as a sealing member that is disposed between the first exterior body 43 and the second exterior body 44 at the outer peripheral portion of the sealing-improving laminate member 41 and seals the inside thereof.

[0137] Therefore, the frame 45 is arranged and bonded to the outer peripheral portion of the sealing improving laminate member 41 so as to be sandwiched between the first exterior body 43 and the second exterior body 44 .

[0138] For example, in Figure 10 In the cross section of , the first exterior body 43 contacts one surface of the frame 45 and the second exterior body 44 contacts the other surface thereof, thereby sealing the frame 45 from the region 41a where the core member 42 is disposed to the second hole 43e.

[0139] The frame 45 is formed of a thermoplastic resin material having electrical insulation and airtightness and a relatively high melting point. Examples of such a material include engineering plastics. Examples of engineering plastics include polyethylene naphthalate resins (PEN), polyphenylene sulfide resins (PPS), and polyphenylene sulfone resins (PPSU).

[0140] The thickness of the frame is not particularly limited, but is preferably 0.05 mm or more and 0.25 mm or less.

[0141] The frame 45 has adhesive placed on its front and back surfaces, so as to adhere to the portions of the first exterior body 43 and the second exterior body 44 that are in contact therewith.

[0142] 2.1.2. Layer structure of the core area

[0143] The layer structure of the region 41a where the core member 42 is arranged is as follows: Figure 9 As shown, a first outer casing 43 is disposed on one surface of a core 42, and a second outer casing 44 is disposed on the other surface. A cavity 43a is formed between the first outer casing 43 and the core 42, and a cavity 44a is formed between the second outer casing 44 and the core 42.

[0144] 2.1.3. Structure of other areas

[0145] In other areas, as described above, the sealing enhancement laminate member 41 is not intended to perform water electrolysis inside thereof, so there is no need to supply water inside. Figure 10 As shown, the first outer casing 43 and the second outer casing 44 are in contact with the frame 45 to be sealed.

[0146] 2.1.4. Effects, etc.

[0147] As described above, according to the water electrolysis stack 40 provided with the laminated member 41 for improving sealing performance, as shown in FIG. Figure 16 As described above, the central portion of the multiple water electrolysis cells arranged between the end plates bulges, and the water electrolysis cells located closest to the end plates become more curved, potentially reducing the sealing performance at the end portions. In contrast, replacing the most curved portions with a sealing-enhancing stack member 41, which is not intended for water electrolysis and does not receive water for electrolysis, reduces the number of water electrolysis cells with significant deformation (curvature), thereby suppressing the reduction in sealing performance within the water electrolysis stack. This suppression of sealing performance can suppress leakage and increase hydrogen pressure.

[0148] In the above description, one sealing-enhancing stacking member 41 is disposed at each end of the water electrolysis cells 10 in the stacking direction. However, this is not limiting, and three or more sealing-enhancing stacking members 41 may be disposed on either side. In this case, as described above, the closer to the end plate, the greater the curvature. Therefore, it is preferable to dispose the sealing-enhancing stacking members 41 near the end plate.

[0149] 2.1.5. Modification

[0150] Since this is a modified example of the form of the sealing performance enhancing laminated member 41 , only the sealing performance enhancing laminated member 41 will be described, and descriptions of the other members will be omitted.

[0151] As described above, the inside of the sealing-enhancing laminated component 41 is sealed by the frame 45. Therefore, the gas enclosed in the cavities 14a and 17a may expand due to load or heat, and the resulting pressure may apply a load to the sealing-enhancing laminated component 41. Therefore, in a modified example, a communicating hole is provided that connects the cavities 14a and 17a to the outside. The gas in the cavities 14a and 17a is released through this communicating hole, thereby reducing the pressure (load).

[0152] Figure 11 This figure shows Modification 1. In this modification, a notch 46 is provided as a communication hole in at least one of the first and second exterior bodies in the region 41 a where the core is disposed, and the cavities 14 a and 17 a are communicated with the outside via the notch 46 .

[0153] Figure 12 1 is a diagram showing a second modification. In this modification, a portion of the surface of the frame 45 that contacts the second exterior body 44 is provided with a non-bonded portion 47. This non-bonded portion 47 functions as a communication hole, thereby connecting the cavities 14a and 17a to the outside.

[0154] Here, the communication hole formed between the frame 45 and the second external housing 44 is described. However, a communication hole may be formed between the frame and the first external housing in response to (or instead of) this.

[0155] Figure 13 This figure shows Modification 3. In this modification, a hole 48 is provided in a portion of the frame 45 to connect the inside and outside of the sealing enhancement laminate member 41. The hole 48 functions as a communication hole to connect the cavity 14a and the cavity 17a to the outside.

[0156] Method 2

[0157] exist Figure 14 2 is a diagram illustrating a water electrolysis stack 50 as an example of an embodiment of the water electrolysis stack according to the present disclosure. Figure 14 Is based on Figure 4 The same perspective diagram. Figure 14As can be seen, the water electrolysis stack 50 according to embodiment 2 is similar to the water electrolysis stack 30 in that a sealing-enhancing stacking member 51 is stacked between the plurality of water electrolysis cells 10. Components other than the sealing-enhancing stacking member 51 are considered identical to those of the water electrolysis stack 30 and are therefore denoted by the same reference numerals and their descriptions are omitted.

[0158] exist Figure 15 2 is a diagram for explaining the structure of a laminated member 51 for improving sealing performance included in this embodiment. Figure 15 This is a plan view of the sealing-enhancing stacking member 51 (seen from the direction of stacking with the water electrolysis cells 10, which is the direction of depth / front of the paper). In this embodiment, the sealing-enhancing stacking member 51 is a flat plate-shaped member.

[0159] The flat plate-shaped material constituting the sealing-enhancing laminated member 51 is conductive and is not particularly limited as long as it is more difficult to bend than the water electrolysis chamber. For example, stainless steel can be used. The plate thickness is also not particularly limited, but is preferably about the same as that of the water electrolysis chamber 10, with a range of 0.8 mm to 1.5 mm being possible. Bendability can be compared through a bending test.

[0160] The sealing-enhancing laminated member 51 is provided with a first hole 41d corresponding to the oxygen electrode inlet manifold 14d, a second hole 51e corresponding to the oxygen electrode outlet manifold 14e, and a third hole 51f corresponding to the hydrogen electrode outlet manifold 14f. When the sealing-enhancing laminated member 51 is laminated with the water electrolysis cell 10, these holes overlap with the corresponding manifolds.

[0161] The number and position of the arranged sealing performance enhancing laminated members 51 are not particularly limited, but a plurality of the laminated members 51 are preferably arranged at predetermined intervals.

[0162] As described above, according to the water electrolysis stack 50 including the sealing improvement laminated member 51, as shown in FIG. Figure 16 As described above, the central portion of the multiple water electrolysis chambers arranged between the end plates swells, and the water electrolysis chambers located closest to the end plates bend more significantly, potentially reducing the sealing performance of the end portions. In contrast, by providing a non-deformable (highly strong and rigid) sealing-enhancing laminated member 51 that is not intended for water electrolysis and is not supplied with water for electrolysis, the number of water electrolysis chambers subject to significant deformation (bending) can be reduced, thereby suppressing a reduction in sealing performance within the water electrolysis stack. This suppression of sealing performance can suppress leakage and increase hydrogen pressure.

Claims

1. A water electrolysis stack comprising a plurality of stacked water electrolysis cells, wherein water is supplied to the water electrolysis cells and electricity is applied to generate hydrogen, wherein: A sealing-improving lamination member is laminated at a predetermined position of the laminated water electrolysis cells. The sealing-improving lamination member is a member that prevents the water from being introduced into the interior thereof.

2. The water electrolysis stack according to claim 1, wherein: The sealing performance-enhancing laminated component comprises: a first outer casing having the same shape as the anode diaphragm of the water electrolysis cell; a second outer casing having the same shape as the cathode diaphragm of the water electrolysis cell; a core member disposed between the first outer casing and the second outer casing; and The frame is disposed between the first outer casing and the second outer casing and bonds the first outer casing and the second outer casing together.

3. The water electrolysis stack according to claim 2, wherein: A communication hole is provided to connect the space between the first exterior body and the second exterior body to the outside.

4. The water electrolysis stack according to claim 3, wherein: The communicating hole is provided in at least one of the first exterior body and the second exterior body.

5. The water electrolysis stack according to claim 3, wherein: The communicating hole is provided on the frame.

6. The water electrolysis stack according to claim 3, wherein: The communication hole is formed between the first exterior body and the frame, or between the second exterior body and the frame.

7. The water electrolysis stack according to claim 2, wherein: The core member is made of the same material as the cathode gas diffusion layer of the water electrolysis cell.

8. The water electrolysis stack according to any one of claims 1 to 7, wherein: The sealing performance improving stack member is disposed at an end portion of the stack body formed by the water electrolysis stack.

9. The water electrolysis stack according to claim 1, wherein: The sealing-improving laminated member is a plate-shaped member that is less susceptible to bending than the water electrolysis cell.

10. The water electrolysis stack according to claim 9, wherein: The sealing performance improving stack member is disposed between the plurality of water electrolysis stacks.

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