Electrode unit produced by resistance welding, electrolytic cell and electrolytic bath comprising such an electrode unit, and corresponding manufacturing method

Abstract

The present application relates to an electrode unit (1216a, 1216b) for an electrolytic cell, the electrode unit comprising a planar electrode (12a, 12b) and a flow field material (16a, 16b), the flow field material being elastically deformable in a direction orthogonal to the planar electrode (12a, 12b) and having a thickness which is greater than the thickness of the electrode (12a, 12b) at least in a central region of the flow field material (16a, 16b), the flow field material (16a, 16b) comprising a peripheral region which is flattened in said direction and is connected to the periphery of the electrode (12a, 12b) by a weld made from a self-fluxing resistance weld. An electrolytic cell and an electrolytic cell stack comprising such an electrode unit (1216a, 1216b) as well as a method of manufacturing such a stack are also described.

Description

[0001] This invention relates to the field of electrolysis, and more specifically to the production of dihydrogen. Background of the Invention

[0002] The overall architecture of an electrolytic cell stack typically consists of cell blocks and spacers. The cells are pressed between a substrate (used to define the cell group and clamp the cells together, as well as seal them) and a distribution plate inserted between each substrate and cell block to enable power supply and distribution to the cells. The cells are electrically stacked in series and fluidly stacked in parallel.

[0003] The purpose of each electrolytic cell is to facilitate the electrolysis of an electrolyte solution (alkaline water, pure water, unpurified water, salt, chloride aqueous solution, bromide aqueous solution, hydrochloric acid aqueous solution, etc.). For example, the function of an electrolytic cell stack is to promote the reaction of water dissociation to produce gaseous dihydrogen (H2) and hydrogen peroxide (O2) after direct current is injected into an alkaline solution (usually containing potassium hydroxide (KOH) or sodium hydroxide (NaOH)). The operating environment requires high precision: an alkaline electrolyte solution; a temperature range of 80°C to 100°C; and the presence of hydrogen peroxide at pressures ranging from 30 bar to 40 bar.

[0004] Each electrolytic cell is considered a product, primarily metallic and conductive (although some parts may be non-metallic), typically consisting of two bipolar plates that frame two flow field materials, which in turn frame two electrodes, usually in the form of metal plates, meshes, or fabrics. In the case of alkaline electrolytic cell stacks, the electrodes are typically made of nickel. The two electrodes (cathode and anode) are separated by a membrane (also called a diaphragm or porous separator in the case of alkaline electrolytic cell stacks), which ensures electrical insulation between the two electrodes, gas separation, and ion conduction within the electrolytic cell.

[0005] exist Figure 1 An exploded perspective view of a prior art electrolytic cell is presented. The electrolytic cell, generally designated 10, comprises two bipolar plates 14 that, when assembled, define an internal volume (or chamber) between them. This internal volume contains a central membrane 11 framed by two electrodes 12a and 12b (anode and cathode, respectively), which are themselves framed by two flow field materials 16. Additionally, the electrolytic cell 10 includes a gasket 13 compressed between the two bipolar plates 14 to seal the internal volume of the electrolytic cell 10.

[0006] The name of bipolar plate 14 derives from the fact that, since all electrolytic cells 10 are adjacent to each other in the electrolytic cell stack, the potential of bipolar plate 14 N will be:

[0007] - Higher than the downstream bipolar plate 14 N+1, such that bipolar plate 14 N will act as the anode in the electrolytic cell 10 defined by bipolar plates 14 N and 14 N+1;

[0008] - Lower than the upstream bipolar plate 14 N-1, such that bipolar plate 14 N will act as the cathode in the electrolytic cell 10 defined by bipolar plates 14 N-1 and 14 N.

[0009] In most cases, each bipolar plate 14 includes a central web surrounded by a ring that performs both mechanical framing and fluid feeding and discharging functions.

[0010] Each electrode 12a, 12b is formed from a fabric of conductive metal wires that allow fluid to pass through.

[0011] Each flow field material 16 is typically formed from a loosely entangled set of metal wires (such as knitted fabric) to form a porous and elastically deformable layer, which is lightly pressed between the bipolar plate 14 and the electrodes 12a, 12b and keeps the electrodes 12a, 12b taut. Each flow field material 16 has two functions: i) to provide a low-resistivity metal path between each bipolar plate 14 and the associated electrodes 12a, 12b (the flow field material 16 is pressed between the bipolar plate 14 and the electrodes 12a, 12b), and ii) to allow proper flow of the electrolyte solution to cool the electrolytic cell stack and transport the generated gases.

[0012] Electrolytic cell stacks are formed by sequentially stacking bipolar plates, flow field materials, electrodes, and membranes, and then clamping them between two substrates. However, this assembly is relatively impractical because it requires handling many heavy components, some of which are very flexible. Purpose of the invention

[0013] The purpose of this invention is to provide a simpler and easier-to-assemble electrolytic cell stack. Summary of the Invention

[0014] To this end, the present invention provides an electrode unit for an electrolytic cell, the electrode unit comprising a planar electrode and a flow field material, the flow field material being elastically deformable along a direction orthogonal to the planar electrode and having a thickness greater than the electrode thickness, at least in the central region of the flow field material, the flow field material including a peripheral region, the peripheral region being flattened along the direction and connected to the periphery of the electrode by a weld made by self-fusion resistance welding, the electrode and the flow field material forming a first surface and a second surface of the electrode unit, respectively, and provided with holes for allowing fluid to travel from one surface to the other.

[0015] "Electrode unit" refers to a unit of electrodes (i.e., anodes or cathodes) arranged sequentially to form an electrolytic cell. Therefore, with the aid of this invention, the electrodes and flow field material form a more easily handled pre-assembled entity (electrode unit). This also has the second advantage of reducing the number of parts to be handled when assembling electrolytic cell stacks. Furthermore, the weld formed by self-fusion resistance welding (used here in the sense that no filler product is required) is a surface weld without the risk of damaging the electrodes. The weld has another advantage: improved electrical contact between the electrodes and the flow field material. Additionally, when the flow field material and / or electrodes are produced based on interwoven wires, the weld locally holds the wires in place and limits the risk of damaging the flow field material and / or electrodes during the handling of the electrode unit.

[0016] The present invention also relates to an electrolytic cell and electrolytic cell stack including such electrode units.

[0017] The electrolytic cell includes at least one first bipolar plate and one second bipolar plate, electrode units of the type described above adjacent to each bipolar plate, and a membrane between the electrode units. One electrode unit forms an anode, and the other electrode unit forms a cathode. A first surface of the electrode unit is adjacent to the membrane, and a second surface of the electrode unit is adjacent to the bipolar plate.

[0018] The electrolytic cell stack includes two substrates that clamp a stack of components containing an electrolytic cell of the type described above.

[0019] Finally, this invention relates to a method for manufacturing an electrolytic cell stack.

[0020] A method for manufacturing an electrolytic cell stack includes a stage of producing electrode units and a stage of stacking bipolar plates, pre-produced electrode units, and membranes, such that each membrane is positioned between two electrode units whose electrodes are adjacent to the membrane, and each flow field material is adjacent to one of the bipolar plates. The stage of producing electrode units includes a step of flattening a peripheral region of the flow field material and a step of welding the flattened region to the periphery of the electrode by self-fusion resistance welding.

[0021] Other features and advantages of the invention will become apparent when reading the following description of specific, non-limiting embodiments thereof. Attached Figure Description

[0022] Please refer to the attached diagram, in which:

[0023] [ Figure 1 ] Figure 1 This is an exploded schematic diagram of an electrolytic cell based on an existing electrolytic cell stack.

[0024] [ Figure 2 ] Figure 2This is a view of the electrolytic cell stack according to the present invention;

[0025] [ Figure 3a ] Figure 3a This is a partial schematic diagram illustrating the first manufacturing step of the electrode unit according to the present invention;

[0026] [ Figure 3b ] Figure 3b This is a partial schematic diagram illustrating the second manufacturing step of the electrode unit according to the present invention;

[0027] [ Figure 3c ] Figure 3c This is a partial schematic diagram illustrating the third manufacturing step of the electrode unit according to the present invention;

[0028] [ Figure 3d ] Figure 3d This is a partial schematic diagram illustrating the fourth manufacturing step of the electrode unit according to the present invention;

[0029] [ Figure 3e ] Figure 3e This is a partial schematic diagram illustrating the fifth manufacturing step of the electrode unit according to the present invention;

[0030] [ Figure 3f ] Figure 3f This is a partial schematic diagram illustrating the sixth manufacturing step of the electrode unit according to the present invention;

[0031] [ Figure 4 ] Figure 4 This is a partial schematic diagram of the cross-section of the bipolar plate of the electrolytic cell during assembly with the two electrode units according to the present invention. Detailed Implementation

[0032] refer to Figure 2 The present invention relates to an electrolytic cell stack comprising a stack of elements extending longitudinally along a general direction A.

[0033] The various components are mainly formed by electrolytic cells, which will be described below.

[0034] The electrolytic cell stack 1 comprises a block 2 containing electrolytic cells 10, each block including at least two electrolytic cells 10, which are continuously mounted to each other along the general direction A. Within the block 2, the electrolytic cells 10 are fluidly connected in parallel and electrically connected in series.

[0035] Two substrates or end plates 3 and 4 are placed at both ends (along the general direction A) of block 2 of electrolytic cell stack 1.

[0036] These substrates 3 and 4 form supports, and the electrolytic cell 10 is compressed between these supports, thereby sealing the electrolytic cell stack 1 and forming high-quality electrical contacts inside the electrolytic cell 10.

[0037] Furthermore, substrates 3 and 4 enable them to withstand forces generated by pressure inside block 2 as well as forces outside block 2, which are necessary to compress block 2.

[0038] Substrates 3 and 4 can act as electrical conductors and current distributors.

[0039] However, preferably, the electrolytic cell stack 1 includes a first distribution plate 5 associated with the first substrate 3 and a second distribution plate 6 associated with the second substrate 4. Thus, the distribution plates 5 and 6 will act as electrical conductors and current distributors.

[0040] The first distribution plate 5 (associated with the positive terminal) is arranged upstream of block 2, and the second distribution plate 6 (associated with the negative terminal) is arranged downstream of said block 2. The concepts of "upstream" and "downstream" should be understood in accordance with the conventional direction of current flow through block 2.

[0041] The first distribution plate 5 is connected to the positive terminal of the electrolytic cell stack 1. A portion of the inner main surface of the first substrate 3 (facing the block 2, and particularly the main surface facing the first distribution plate 5) is then covered with an electrical insulating material patch. This portion is, for example, located at the center of the inner main surface.

[0042] The second distribution plate 6 is connected to the negative terminal of the electrolytic cell stack 1. The second substrate 4 will be at the same potential and also serves as a passage for supplying the electrolyte solution and releasing the same solution loaded with the gas formed during electrolysis in block 2.

[0043] Therefore, holes are formed in the second substrate 4. These holes typically have different cross-sections between the two main surfaces of the second substrate 4. For example, the outer main surface (the main surface facing outwards from block 2) includes at least one or two holes (e.g., cylindrical) for supplying the electrolyte solution and two holes for discharging the heated electrolyte solution and electrolytic reaction products. For the same purpose, at least three or four holes, such as those having an elongated oval shape, are drilled on the inner main surface of the second substrate 4 (opposite to the outer main surface) to improve fluid distribution or collection. For example, the holes on the outer main surface are equipped with flanges suitable for attaching inlet and outlet pipes for the electrolyte solution.

[0044] Furthermore, the electrolytic cell stack 1 is supplied with direct current. For example, the first distribution plate 5 is at a potential of several hundred volts, while the second distribution plate 6 is at a potential of 0 volts (the electrolytic cell stack 1 typically comprises between 10 and 400, preferably between 100 and 350, electrolytic cells 10, which have an electrolytic cell voltage of approximately 2 volts at the beginning of their rated life and preferably less than 1.85 volts). The supply and discharge of the electrolyte solution are carried out through the second distribution plate 6 and the second substrate 4, the second distribution plate 6 having a potential of 0 volts, which avoids any current leakage (the potential of the second distribution plate 6 is the ground potential).

[0045] Inside the electrolytic cell stack 1, current flows through the electrolyte solution through membrane 11, which will be described below. Within block 2 are gaskets (which will be described below): these gaskets are chosen to be made of a material with a resistance much higher than that of the electrolyte solution.

[0046] The electrolytic cell stack 1 includes end spacers (not shown) disposed between the first distribution plate 5 and the first substrate 3. The first substrate 3 is now grounded such that the potential difference at the end spacers reaches the same value as the voltage applied between the positive and negative terminals of the electrolytic cell stack 1, for example, approximately 700 volts. For this reason, the first substrate 3 is electrically isolated from block 2. For example, the electrolytic cell stack 1 includes a layer (not shown) made of an electrically insulating material disposed between the first substrate 3 and the first distribution plate 5. This layer is, for example, an additional disk or a deposit formed on the first substrate 3 and / or the first distribution plate 5.

[0047] The electrolytic cell stack 1 includes means for securing the individual electrolytic cells 10 to each other by a combination clamp. For example, the securing means includes a plurality of pull rods 7. Each pull rod 7 extends in a straight line in the stacking direction of the electrolytic cell stack 1. Thus, each pull rod 7 extends longitudinally in the electrolytic cell stack 1 parallel to the general direction A. Each pull rod 7 is configured as a bar. Therefore, the pull rods 7 all extend parallel to each other. The pull rods 7 are located on the periphery of each electrolytic cell 10. Preferably, the pull rods 7 are distributed around the block 2, preferably at regular intervals.

[0048] The pull rod 7 extends through the substrates 3 and 4 of the electrolytic cell stack 1, through specific holes in the substrates 3 and 4, and thus each has two ends located outside the block 2.

[0049] Preferably, the pull rod 7 is partially covered by a sleeve made of an electrically insulating material. This allows short circuits to be avoided between the electrolytic cells 10 in the event of contact or splashing. For example, the sleeve extends over the entire section between the two substrates 3 and 4 in the arrangement of the pull rod 7.

[0050] Preferably, the end of the tie rod 7 is threaded. For example, the thread at the end is a rolled thread. Rolled threads will have the advantage of making the machining of the tie rod 7 easier, especially if the tie rod 7 has a large length, such as several meters.

[0051] The fixing device also includes a nut 8 screwed onto the end of the pull rod 7. The nut 8 allows the two substrates 3 and 4 to be screwed together, and thus the individual electrolytic cells 10 to be screwed together, which ensures a good seal of the electrolytic cell stack 1 of the electrolytic cells 10.

[0052] Preferably, the fixing device further includes means for pre-tightening the two substrates 3 and 4 to each other and thus pre-tightening the respective electrolytic cells 10 to each other. The pre-tightening means also allows for the absorption of deformation and / or thickness variations of the constituent elements of the electrolytic cell stack 1 caused by changes in thermal expansion or mechanical stress (e.g., pressure within the electrolytic cell stack 1) both externally and internally. The pre-tightening means is received at the end of the pull rod 7 such that, for a given end, the pre-tightening means is positioned between the nearest substrate (3 or 4) and the nut 8 positioned at the same end. For example, the fixing device includes a spring washer 9, such as a Belleville washer. The spring washer 9 is received at the end of the pull rod 7. More precisely, here, the spring washer 9 is positioned on the outer portion of each pull rod 7 as the pull rod 7 passes through the nearest substrate (3 or 4).

[0053] Therefore, the fixing device allows the electrolytic cell stack 1 to specifically cope with changes in thermal expansion and / or mechanical stress (e.g., pressure inside the electrolytic cell stack 1) both externally and internally. However, the pre-tightening device is optional.

[0054] In this example, all the electrolytic cells 10 in the electrolytic cell stack 1 are identical to each other, such that the following references Figure 3 and... Figure 4 The description of electrolytic cell 10 also applies to the description of other electrolytic cells 10.

[0055] refer to Figure 4 The electrolytic cell 10 includes a central membrane 11 (indicated by a double-dotted line) framed by two electrodes 12a and 12b (anode and cathode, respectively). These two electrodes are themselves framed by two flow field materials 16a and 16b, which are in turn framed by two identical bipolar plates 14. Furthermore, the electrolytic cell 10 also includes a gasket 13 (indicated by a double-dotted line) that is compressed between the two bipolar plates 14 of the electrolytic cell 10.

[0056] The membrane 11 and bipolar plate 14, which are known to exist, are made of materials capable of withstanding the predominantly corrosive environment inside the electrolytic cell 10, and will not be described in detail here.

[0057] The anode 12a can be a perforated plate, mesh, wire mesh, stretched metal mesh plate, metal wool, etc., to realize the flow of electrolyte and the discharge of bubbles.

[0058] The cathode 12b can be a perforated plate (i.e., drilled with holes or made of stretched metal mesh), fabric or mesh, mesh or grid, cotton or metal knitted fabric, etc., to enable the flow of electrolyte and the discharge of bubbles.

[0059] The anode 12a and the cathode 12b may be identical or different from each other. For example, different materials and / or coatings may be provided for the anode 12a and the cathode 12b depending on the products that the anode 12a and the cathode 12b are intended to contact, the chemical reactions involved, the operating conditions, etc.

[0060] The flow field material 16a and the flow field material 16b have the same shape and are formed, for example, by stretching metal mesh, metal wool, corrugated metal sheet, foam metal, etc., to realize the flow of electrolyte and the discharge of bubbles.

[0061] The flow field material 16a and the flow field material 16b may be identical or different from each other. For example, different materials and / or coatings may be provided for the flow field material 16a and the flow field material 16b depending on the products that the flow field material 16a and the flow field material 16b are intended to contact, the chemical reactions involved, the operating conditions, etc.

[0062] According to the invention, the thickness of the flow field material 16a is greater than the thickness of the anode 12a at all locations except for the peripheral regions 16a', which are flattened and connected to the periphery of the anode 12a by at least one weld made by self-fusion resistance welding to form an electrode unit 1216a (also referred to as an anode unit). Here, the flattened region 16a' is in the form of a point or a segment (straight or arc-shaped) or a combination of both. The weld can be continuous or discontinuous and is located only on the periphery. As a variation, in addition to weld points or weld lines in the peripheral regions, the flattened region can include weld points or weld lines distributed across the entire surface of the flow field material 16a to ensure uniform current distribution across the entire anode 12a.

[0063] According to the invention, the thickness of the flow field material 16b is greater than the thickness of the cathode 12b at all locations except for the peripheral regions 16b', which are flattened and connected to the periphery of the cathode 12b by at least one weld made by self-fusion resistance welding to form an electrode unit 1216b (also called a cathode unit). Here, the flattened region 16b' is in the form of a point or a segment (straight or arc-shaped) or a combination of both. The weld can be continuous or discontinuous and is located only on the periphery. As a variation, in addition to weld points or weld lines in the peripheral regions, the flattened regions can include weld points or weld lines distributed across the entire surface of the flow field material 16b to ensure uniform current distribution across the entire anode 12b.

[0064] In order to form the electrolytic cell 10, two bipolar plates 14 are pressed together in such a way that the bipolar plates 14 define an internal volume between them, which is sealed around the periphery by a gasket 13 clamped between the rings 142 of the two bipolar plates 14.

[0065] The internal volume is divided into two halves by the membrane 11. The anode unit 1216a is located on the first side of the membrane, and the flow field material 16a of the anode unit abuts against the first surface of the central web 141 of the first bipolar plate 14. The cathode unit 1216b is located on the second side of the membrane, and the flow field material 16b of the cathode unit abuts against the second surface of the central web 141 of the second bipolar plate 14. Each flow field material 16a, 16b is elastically deformable along a direction orthogonal to the electrodes 12a, 12b, and applies pressure to the central web 141 and the electrodes 12a, 12b.

[0066] The central web 141 acts as a current collector and exchanges the current with the electrode units 1216a, 1216b located on both sides of the central web 141.

[0067] Furthermore, the bipolar plate 14 includes conduits that extend completely through the bipolar plate and are dedicated to the supply of electrolyte solution to the internal volume of the electrolytic cell 10 and the release of electrolytic products from the internal volume of the electrolytic cell 10.

[0068] It should be noted that all bipolar plates 14 within the electrolytic cell stack 1 are separated in pairs by spacers 13, and each bipolar plate 14 serves as the cathode of one electrolytic cell 10 and the anode of the adjacent electrolytic cell 10.

[0069] The fabrication of the electrolytic cell stack 1 will now be described.

[0070] In the first stage, the integral components (membrane 11, electrodes 12a and 12b, flow field material 16a, 16b, bipolar plate 14, gasket 13) are manufactured in a manner known per se.

[0071] During the second stage, electrode units 1216a and 1216b are produced according to the present invention. It will be recalled that each electrode unit 1216a, 1216b consists of flow field materials 16a, 16b and electrodes 12a, 12b.

[0072] refer to Figures 3a to 3f Each electrode unit 1216a, 1216b is manufactured through the following steps:

[0073] -Deposit electrodes 12a and 12b on welding station B ( Figure 3a );

[0074] - Deposit flow field material 16a, 16b on electrodes 12a, 12b ( Figure 3b );

[0075] - By means of the molding die P, the periphery of the flow field material 16a and 16b is locally flattened at the positions of the flattened regions 16a' and 16b'. Figure 3c );

[0076] -The peripheral parts of the flow field materials 16a and 16b are locally welded at the locations of the flat regions 16a' and 16b' using at least one welding head S. Figure 3d );

[0077] -The flow field materials 16a, 16b and electrodes 12a, 12b are cut together into the final dimensions of electrode units 1216a, 1216b using, for example, a laser beam D projected by a laser emitter or any other cutting tool. Figure 3e );

[0078] -Remove electrode units 1216a and 1216b from welding station B. Figure 3f ).

[0079] The welding is performed using a self-fusion resistance welding method. Welding parameters are determined to hold the electrode wire and the flow field material wire together, while limiting the fusion of the wires to the degree strictly necessary to achieve a fixation strength sufficient to allow for manual and automatic handling of the assembly formed in this manner without causing significant wire loss.

[0080] The following steps can be provided before welding:

[0081] - The steps of cleaning the electrodes 12a, 12b and / or the flow field materials 16a, 16b in the area to be welded in order to facilitate welding; and / or

[0082] - The step of pickling the electrodes 12a, 12b and / or flow field materials 16a, 16b in the area to be welded to remove their surface layer in order to promote welding.

[0083] This cleaning and / or acid washing can be performed, for example, by using a laser.

[0084] Electrode units produced in this manner can be directly used to assemble electrolytic cell stack 1, as described below.

[0085] The assembly of the electrolytic cell stack 1, which has been produced in the third stage of the manufacturing process, will now be described.

[0086] According to the first step, the following components are stacked sequentially on the first substrate 3 and the first distribution plate 5: bipolar plate 14, anode unit 1216a having a flow field material 16a abutting the central web 141 of the bipolar plate 14, membrane 11, cathode unit 1216b having a cathode 12b oriented toward the membrane 11, bipolar plate 14, etc., in order to form a continuous electrolytic cell 10.

[0087] In the second step, the last electrolytic cell 10 is covered by the second distribution plate 6, which is itself covered by the second substrate 4, thereby defining the electrolytic cell stack 1.

[0088] During the third step, the newly assembled electrolytic cell stack 1 is compressed and placed using the pull rod 7, nut 8 and spring washer 9.

[0089] When the voltage across the terminals of each electrolytic cell 10 is different and the current is distributed only at one or more points around each distribution plate 5 and 6, this arrangement of thick distribution plates 5 and 6 and thin planar bipolar plates 14 allows for uniformity of current in all electrolytic cells 10 of the electrolytic cell stack 1.

[0090] Furthermore, the bipolar plates 14 within block 2 are precisely parallel to each other due to their specific shape and the good clamping of each gasket 13. This further improves the uniformity of current in all electrolytic cells 10.

[0091] The assembly method should ideally allow each gasket 13 to specifically:

[0092] - It deforms according to the geometry applied by the bipolar plate 14 that clamps the gasket.

[0093] - To bring the material of the gasket into the range of elastic behavior (centered on the operating point of the electrolytic cell stack 1).

[0094] - To achieve the desired clamping value, the required seals and electrical contacts between the various components are combined to achieve the envisioned energy performance.

[0095] The nominal operating point of the electrolytic cell stack 1 is, for example, 85 degrees Celsius at 3 MPa.

[0096] As a variant, a pre-assembly including bipolar plate 14, anode unit 1216a, and cathode unit 1216b can be formed, such as Figure 4 As shown.

[0097] In this pre-component:

[0098] - The central portion of the flow field material 16a of the anode unit 1216a abuts against the first surface of the central web 141 of the bipolar plate 14, and the periphery of the flow field material 16a of the anode unit 1216a is welded (e.g., by resistance welding or laser welding) to the first surface of the ring 142 of the bipolar plate 14, while compressing the central portion of the flow field material 16a; and

[0099] - The central portion of the flow field material 16b of the cathode unit 1216b abuts against the second surface of the central web 141 of the bipolar plate 14, and the periphery of the flow field material 16b of the cathode unit 1216b is welded (e.g. by resistance welding or laser welding) on ​​the second surface of the ring 142 of the bipolar plate 14, while compressing the central portion of the flow field material 16b.

[0100] It should be understood that the thickness of the central portion of the flow field materials 16a and 16b is greater than the thickness of the flat regions 16a' and 16b' and is also greater than the thickness of the anode 12a and the cathode 12b.

[0101] The pre-components produced in this way can then be stacked with membrane 11 to form block 2 of electrolytic cell 10.

[0102] Of course, the invention is not limited to the described embodiments, but includes any variations that fall within the scope of the invention as defined by the claims.

[0103] (Multiple) end gaskets may be different from gasket 13.

[0104] The electrolytic cell stack 1 can be assembled in a different manner than that already described.

[0105] The electrolytic cell stack 1 can be used horizontally, vertically, or in any other position. The electrolytic cell stack 1 can be assembled horizontally, vertically, or in any other position. Preferably, the electrolytic cell stack 1 is assembled vertically and used horizontally.

[0106] It is possible to have only a single conduit associated with the feed of the electrolyte solution and a single conduit associated with the discharge of each electrolytic product. However, for redundancy in case one of the conduits becomes blocked, it is preferable to have two conduits associated with the feed of the electrolyte solution and / or two conduits associated with the discharge of each electrolytic product. Typically, the distribution plates 5, 6 may contain only a single conduit, which leads at each end of its end to a corresponding main surface in the main surface of the distribution plates 5, 6.

[0107] Similarly, for redundancy, it is preferable to have two grooves associated with each end of each conduit so as to communicate with the internal volume of the electrolytic cell 10.

[0108] The catheters can be different from each other.

[0109] As mentioned above, the two distribution plates 5 and 6, each associated with one end of block 2, can be different from each other, rather than the same.

[0110] For example, the distribution plates 5 and 6 may include at least one conduit that leads at least one end of its ends to a reinforcement of the distribution plates 5 and 6. Optionally, the conduit will open at least one end of its ends at a location sufficiently close to the outer periphery of one of the main surfaces to allow for complete or near-complete drainage (draining of liquids and / or gases present in the space between the distribution plates 5 and 6 in question and the opposing substrates 3 and 4). Optionally, the conduit may be formed to lead at a first end to a reinforcement of a first main surface of the distribution plates 5 and 6, and at a second end to a reinforcement of a second main surface of the distribution plates 5 and 6, so as to establish communication between the two reinforcements.

[0111] The electrolytic cell stack 1 may include three electrodes 12, namely, two end cathodes 12b and a central anode 12a.

[0112] The spring washer 9 can be placed at both ends of the pull rod 7 or at a single end of these ends, and / or can be replaced by any elastic compression member.

[0113] The flattening and welding of the surrounding area can be performed simultaneously or sequentially (in this order).

[0114] The flow field materials 16a and 16b can be flattened over their entire periphery and then welded to electrodes 12a and 12b only on a portion of that periphery or over the entire length of that periphery.

[0115] In the described method, the size of the electrode units is determined after welding by cutting the periphery of the electrode units. This operation is optional: the flow field materials 16a, 16b and the electrodes 12a, 12b can have their final dimensions before they are welded to each other. However, this requires that the flow field materials 16a, 16b be accurately centered relative to the electrodes 12a, 12b before the peripheral regions of the flow field materials 16a, 16b are flattened and welded to the electrodes 12a, 12b.

[0116] Cleaning and / or pickling can be performed entirely on electrodes 12a, 12b and / or flow field materials 16a, 16b or only in the area to be welded.

[0117] Each electrolytic cell 10 may contain only a single electrode unit formed according to the present invention.

[0118] The flow field materials 16a and 16b, as well as the electrodes 12a and 12b, conventionally have a flat, circular shape. Of course, other shapes are also possible, particularly squares, rectangles, hexagons, etc.

Claims

1. An electrode unit (1216) for an electrolytic cell (10), the electrode unit comprising a planar electrode (12) and a flow field material (16), the flow field material being elastically deformable along a direction orthogonal to the electrode (12) and having a thickness greater than the thickness of the electrode (12) at least in the central region of the flow field material (16), the flow field material (16) comprising a peripheral region, the peripheral region being flattened along the direction and connected to the periphery of the electrode (12) by a weld made by self-fusion resistance welding, the electrode and the flow field material forming a first surface and a second surface of the electrode unit, respectively, and provided with holes for fluid to travel from one surface to the other surface.

2. The electrode unit (1216) as described in claim 1, wherein, The surrounding area includes at least one dotted area.

3. The electrode unit (1216) as described in claim 1 or 2, wherein, The surrounding area includes at least one area in the form of segments.

4. The electrode unit (1216) as described in any of the preceding claims, wherein, The electrodes are perforated plates, fabrics, meshes, or grids.

5. An electrolytic cell (10) comprising at least one first bipolar plate and a second bipolar plate (14), electrode units (1216) adjacent to each bipolar plate, and a membrane (11) between the electrode units (1216), wherein the electrode units (1216) are as described in any of the preceding claims, one electrode unit forming an anode and the other electrode unit forming a cathode, a first surface of the electrode unit abutting the membrane, and a second surface of the electrode unit abutting the bipolar plate.

6. An electrolytic cell stack comprising two substrates (3, 4) clamping a stack of elements (2) containing electrolytic cells (10), each electrolytic cell (10) as described in the preceding claim.

7. A method for manufacturing an electrolytic cell stack (1) as claimed in the preceding claim, comprising a stage of producing electrode units and a stage of stacking bipolar plates (14), the pre-produced electrode units (1216) and membranes (11) in such a way that each membrane is positioned between two electrode units, the electrodes of the two electrode units being adjacent to the membranes, and each flow field material being adjacent to one of the bipolar plates, the stage of producing the electrode units (1216) comprising a step of flattening a peripheral region of the flow field material (16) and a step of welding the flattened region to the periphery of the electrode (12) by self-fusion resistance welding.

8. The method of claim 7, wherein, The flattening and welding of the surrounding area are performed simultaneously.

9. The method of claim 7 or 8, wherein, Prior to the production of the electrode unit (1216), at least one of the electrode (12) and the flow field material (16) is cleaned in the area to be welded.

10. The method of claim 7 or 8, wherein, Prior to the production of the electrode unit (1216), at least one of the electrode (12) and the flow field material (16) is pickled in the area to be welded.

11. The method according to any one of claims 7 to 10, wherein, The size of the electrode unit is determined by cutting the periphery of the electrode unit (1216) after welding.

12. The method according to any one of claims 7 to 11, wherein, The production of the electrode unit (1216) is followed by a pre-assembly operation, which includes fixing at least one electrode unit (1216) onto each bipolar plate (14).

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