Electrode unit made by resistive welding, electrolytic cell and electrolyzer comprising same, and manufacturing method

Abstract

Electrodic unit (1216) for an electrolytic cell (10), a planar electrode (12) and an interlayer (16) which is elastically deformable in a direction normal to the planar electrode (12) and which has a thickness greater than a thickness of the electrode (12) at least in a central zone of the interlayer (16), the interlayer (16) comprising peripheral zones crushed in said direction and connected to a periphery of the electrode (12) by a weld carried out by resistive autogenous welding. Electrolytic cell and electrolyzer stack comprising such electrodic units. Method of manufacturing such a stack. FIGURE OF THE ABSTRACT: Fig. 4

Description

Title of the invention: Electrodic unit produced by resistive welding, electrolytic cell and electrolyser comprising same, and manufacturing method

[0001] The invention relates to the field of electrolysis and more particularly the production of dihydrogen.

[0002] BACKGROUND OF THE INVENTION

[0003] The overall architecture of an electrolyzer stack (generally referred to as an "electrolyzer stack") is usually made up of a block of electrolytic cells and sealing gaskets, said electrolytic cells being pressed between bottom plates (making it possible to delimit the set of electrolytic cells and to ensure the clamping of said electrolytic cells between them and their sealing) and distribution plates interposed between each bottom plate and the block of electrolytic cells to allow the power supply and electrical distribution of the electrolytic cells. The electrolytic cells are stacked in series from an electrical point of view and in parallel from a fluidic point of view.

[0004] Each electrolytic cell has the purpose of promoting the electrolysis of an electrolytic solution (alkaline water, pure water, unpurified water, salt, aqueous chloride solution, aqueous bromide solution, aqueous hydrochloric acid solution, etc.). For example, the functionality of an electrolyzer stack is to promote the reaction of production of dihydrogen (H2) and dioxygen (02) gas resulting from the dissociation of water after injecting a direct electric current into an alkaline solution, generally comprising potassium hydroxide (KOH) or sodium hydroxide (NaOH). The working environment is very restrictive: basic electrolytic solution; temperature of 80 to 100°C; presence of dioxygen at a pressure of 30 to 40 bars...

[0005] Each electrolytic cell, considered as a mainly metallic and conductive part (but some parts of which may be non-metallic), is generally composed of two bipolar plates, framing two interlayers (better known under the English term "flow field material"), themselves framing two electrodes generally in the form of plates or grids or metal fabrics. In the case of an alkaline electrolyzer stack, said electrodes are generally made of nickel. The two electrodes (a cathode and an anode) are separated by a membrane (also called a diaphragm or porous separator in the case of the alkaline electrolyzer stack), which ensures electrical insulation between the two electrodes, gas separation and ionic conduction within the electrolytic cell.

[0006] An electrolytic cell of the prior art is shown in exploded perspective in [Fig. 1]. The electrolytic cell, bearing the general reference 10, comprises two bipolar plates 14 which, when assembled, define between them an internal volume (or chamber) in which there is a central membrane 11 framed by two electrodes 12a and 12b (an anode and a cathode, respectively) which are themselves framed by two spacers 16 (or "flow field material" in English). Furthermore, the electrolytic cell 10 also comprises a seal 13 compressed between the two bipolar plates 14 of the electrolytic cell 10 to ensure the sealing of the internal volume of the electrolytic cell 10.

[0007] The name bipolar plate 14 comes from the fact that, as the electrolytic cells 10 are all placed next to each other in an electrolyzer stack, a bipolar plate 14 N will have a potential:

[0008] - higher compared to the downstream 14 N+l bipolar plate, so that the plate bipolar 14 N will play the role of anode within an electrolytic cell 10 defined by the bipolar plates 14 N and 14 N+1;

[0009] - lower compared to the upstream 14 Nl bipolar plate, so that the plate bipolar 14 N will play the role of cathode within an electrolytic cell 10 defined by the bipolar plates 14N-1 and 14 N.

[0010] In most cases, each bipolar plate 14 comprises a central web surrounded by a ring providing a mechanical reinforcement function, and a fluid supply and evacuation function.

[0011] Each electrode 12a, 12b is formed from a fabric of electrically conductive metal wires allowing fluids to pass through.

[0012] Each spacer 16 is generally formed from a set of loosely entangled metal wires (like a knit) to form a porous and elastically deformable layer which is lightly pressed between the bipolar plate 14 and the electrode 12a, 12b and keeps the electrode 12a, 12b taut. Each spacer 16 has two functions: i) to provide a low resistivity metal path between each bipolar plate 14 and the associated electrode 12a, 12b (the spacer 16 being pressed between said bipolar plate 14 and said electrode 12a, 12b) and ii) to allow suitable circulation of the electrolytic solution for cooling the electrolyzer stack and transporting the generated gases.

[0013] The electrolyser stack is formed by successively stacking the bipolar plates, the spacers, the electrodes and the membranes and then clamping these between two base plates. However, this assembly is relatively inconvenient, because it requires the handling of many bulky parts, some of which are very flexible.

[0014] SUBJECT OF THE INVENTION

[0015] An aim of the invention is to propose an electrolyser stack that is simpler and easier to assemble. Summary of the invention

[0016] For this purpose, according to the invention, there is provided an electrodic unit for an electrolytic cell, a planar electrode and an interlayer which is elastically deformable in a direction normal to the planar electrode and which has a thickness greater than a thickness of the electrode at least in a central zone of the interlayer, the interlayer comprising peripheral zones crushed in said direction and connected to a periphery of the electrode by a weld carried out by resistive autogenous welding.

[0017] By "electrodic unit" is meant a unit arranged to form an electrode of the electrolytic cell, that is to say either an anode or a cathode. Thus, thanks to the invention, the electrode and the interlayer form a pre-assembled assembly (the electrodic unit) which is easier to handle. This also has the second advantage of allowing a reduction in the number of parts to be handled when assembling the electrolyser stack. In addition, the weld carried out by autogenous welding (here used in the sense of without filler product) resistive is a surface weld which does not risk damaging the electrode. The weld has this other advantage of improving the electrical contact between the electrode and the interlayer.Furthermore, when the interlayer and / or the electrode are made from interlaced wires, the welding locally holds the wires in place and limits the risk of damage to the interlayer and / or the electrode when handling the electrodic unit.

[0018] The invention also relates to an electrolytic cell and an electrolyzer stack comprising such an electrodic unit.

[0019] The invention finally relates to a method for manufacturing an electrolyser stack.

[0020] Other characteristics and advantages of the invention will emerge from reading the following description of particular and non-limiting embodiments of the invention. Brief description of the drawings

[0021] Reference will be made to the accompanying drawings, among which:

[0022] [Fig.l] [Fig.l] is an exploded schematic view of an electrolytic cell of a electrolyzer stack according to the prior art;

[0023] [Fig.2] [Fig.2] is a view of an electrolyzer stack according to the invention;

[0024] [Fig.3a] [Fig.3a] is a partial schematic view illustrating a first stage of manufacturing an electrodic unit according to the invention;

[0025] [Fig.3b] [Fig.3b] is a partial schematic view illustrating a second step of manufacturing the electrodic unit according to the invention;

[0026] [Fig.3c] [Fig.3c] is a partial schematic view illustrating a third step of manufacturing the electrodic unit according to the invention;

[0027] [Fig.3d] [Fig.3d] is a partial schematic view illustrating a fourth step of manufacturing the electrodic unit according to the invention;

[0028] [Fig.3e] [Fig.3e] is a partial schematic view illustrating a fifth step of manufacturing the electrodic unit according to the invention;

[0029] [Fig.3f] [Fig.3f] is a partial schematic view illustrating a sixth step of manufacturing the electrodic unit according to the invention;

[0030] [Fig.4] [Fig.4] is a partial schematic view, in cross-section, of a bipolar plate of an electrolytic cell being assembled with two electrode units according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] With reference to [Fig.2], the invention relates to an electrolyser stack comprising a stack of elements extending longitudinally in a general direction A.

[0032] The different elements are mainly formed by electrolytic cells which will be described below.

[0033] The electrolyser stack 1 comprises a block 2 of electrolytic cells 10 which comprises at least two electrolytic cells 10 which are mounted adjacent to each other in the general direction A. Within the block 2, the electrolytic cells 10 are mounted in parallel from a fluidic point of view and in series from an electrical point of view.

[0034] At the two ends (along the general direction A) of the block 2 of the electrolyser stack 1 are arranged two end or bottom plates 3 and 4.

[0035] These bottom plates 3 and 4 form supports between which the electrolytic cells 10 are compressed so that the electrolyser stack 1 is sealed and so that a good quality electrical contact is created inside the electrolytic cells 10.

[0036] Furthermore, the bottom plates 3 and 4 make it possible to support the forces generated by the internal pressure in block 2 as well as the external forces in block 2 necessary to ensure the compression of block 2.

[0037] The bottom plates 3 and 4 can act as an electrical conductor and current distributor.

[0038] Nevertheless, the electrolyser stack 1 preferably comprises a first distribution plate 5 associated with the first bottom plate 3 and a second distribution plate 6 associated with the second bottom plate 4. These are then the plates distribution 5 and 6 which will here play the role of electrical conductors and current distributors.

[0039] The first distribution plate 5 (associated with the positive terminal) is arranged upstream of the block 2 and the second distribution plate 6 (associated with the negative terminal) is arranged downstream of said block 2. The notions "upstream" and "downstream" are understood according to the conventional direction of circulation of the current through the block 2.

[0040] The first distribution plate 5 is connected to the positive terminal of the electrolyser stack 1. Then, a portion of the internal main face of the first bottom plate 3 (main face facing the block 2 and in particular the first distribution plate 5) is covered with a pad made of electrically insulating material. Said portion is for example arranged in the centre of said internal main face.

[0041] The second distribution plate 6 is connected to the negative terminal of the electrolyser stack 1. The second bottom plate 4 will be at the same potential and also serves as a gateway for the supply of an electrolytic solution and the exhaust of this same solution charged with the gases formed during the electrolysis in the block 2.

[0042] Thus, holes are provided in said second bottom plate 4. Said holes often have a different section between the two main faces of the second bottom plate 4. For example, the external main face (the one facing the outside of the block 2) has at least one or two holes (for example cylindrical in shape) for supplying electrolytic solution and two holes for discharging electrolytic reaction products in addition to the heated electrolytic solution. At least three or four holes are drilled on the internal main face (opposite the external main face) of said second bottom plate 4 for the same purpose, and for example oblong holes to improve the distribution or collection of fluids. For example, the holes in the external main face are equipped with suitable flanges for connecting the inlet and return pipes for the electrolytic solution.

[0043] Furthermore, the electrolyser stack 1 is here supplied with direct current. For example, the first distribution plate 5 has a potential of several hundred volts while the second distribution plate 6 has a potential of 0 volts (the electrolyser stack 1 typically comprises between 10 and 400, preferably between 100 and 350, electrolytic cells 10 having a cell voltage of the order of 2 volts and preferably less than 1.85 volts at the nominal point at the start of life). The supply and evacuations of electrolytic solution are carried out at the level of the second distribution plate 6 and the second bottom plate 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 being that of Earth).

[0044] Inside the electrolyser stack 1, the current passes through the electrolytic solution through a membrane 11 which will be introduced below. Within the block 2 there are seals (which will be described below): these seals are chosen from a material having a much greater electrical resistance than that of the electrolytic solution.

[0045] The electrolyser stack 1 comprises an end seal (not visible in the figures) arranged between the first distribution plate 5 and the first bottom plate 3. However, the first bottom plate 3 is earthed so that the potential difference at said end seal reaches the same value as the voltage applied between the positive and negative terminals of the electrolyser stack 1, for example, substantially 700 volts. As a result, the first bottom plate 3 is electrically insulated from the block 2. For example, the electrolyser stack 1 comprises a layer (not visible in the figures) made of electrically insulating material, a layer arranged between the first bottom plate 3 and the first distribution plate 5. The layer is for example an added disc or a deposit made on the first bottom plate 3 and / or the first distribution plate 5.

[0046] The electrolyser stack 1 comprises means for fixing the different electrolytic cells 10 together by common clamping. For example, the fixing means comprise a plurality of tie rods 7. Each tie rod 7 extends rectilinearly in the stack of the electrolyser stack 1. Each tie rod 7 thus extends longitudinally in the electrolyser stack 1 parallel to the general direction A. Each tie rod 7 is shaped as a rod. The tie rods 7 therefore all extend parallel to each other. The tie rods 7 are positioned on the periphery of the different electrolytic cells 10. Preferably, the tie rods 7 are distributed all around the block 2 and preferably at a regular interval.

[0047] The tie rods 7 extend through the bottom plates 3 and 4 of the electrolyser stack 1, through specific holes in said bottom plates 3 and 4, and thus each have two ends external to the block 2.

[0048] Preferably, the tie rods 7 are partly covered with a sleeve made of electrically insulating material. This makes it possible to avoid short circuits between the electrolytic cells 10 in the event of contact or projection. For example, the sleeve extends over the entire section of the tie rod 7 arranged between the two bottom plates 3 and 4.

[0049] Preferably, the ends of the tie rods 7 are threaded. For example, the threads at the ends are rolled threads. The rolled threads will have the advantage of making the machining of the tie rods 7 easier, particularly if the tie rods 7 are of a significant length, for example several meters in length.

[0050] The fixing means also comprise nuts 8 screwed onto the ends of the tie rods 7. The nuts 8 make it possible to constrain the two base plates 3 and 4 between them, and therefore the different electrolytic cells 10 between them, which ensures good sealing of the electrolyzer stack 1 of electrolytic cells 10.

[0051] Preferably, the fixing means also comprise means for prestressing the two bottom plates 3 and 4 between them and therefore the different electrolytic cells 10 between them. Said prestressing means also make it possible to absorb the deformations and / or variations in thickness of the elements constituting the electrolyser stack 1, due to thermal expansion or to variations in external and internal mechanical stresses in the electrolyser stack 1 (such as for example the internal pressure in the electrolyser stack 1). The prestressing means are received on the ends of the tie rods 7 so as to be arranged, for a given end, between the closest bottom plate (3 or 4) and the nuts 8 arranged on the same end. For example, the fixing means comprise spring washers 9 such as Belleville washers. The spring washers 9 are received on the ends of the tie rods 7.The spring washers 9 are more precisely arranged here on each tie rod 7, at the level of the external part of said tie rod 7, when the latter has passed through the nearest base plate (3 or 4).

[0052] The fixing means thus enable the electrolyser stack 1 to cope in particular with thermal expansions and / or variations in mechanical stresses external and internal to the electrolyser stack 1 (such as, for example, the internal pressure to the electrolyser stack 1). However, the prestressing means are optional.

[0053] In the present case, all the electrolytic cells 10 of the electrolyser stack 1 are identical to each other so that the following description of an electrolytic cell 10 in relation to FIGS. 3 and 4 is also applicable to the description of the other electrolytic cells 10.

[0054] With reference to [Fig. 4], such an electrolytic cell 10 comprises a central membrane 11 (shown in double dot-dash line) which is framed by two electrodes 12a and 12b (an anode and a cathode, respectively) which are themselves framed by two spacers 16a, 16b (or flow field material in English) which are themselves framed by two bipolar plates 14 identical to each other. Furthermore, the electrolytic cell 10 also comprises a seal 13 (shown in double dot-dash line) which is compressed between the two bipolar plates 14 of the electrolytic cell 10.

[0055] The membrane 11 and the bipolar plates 14, known in themselves, are made of materials capable of withstanding the corrosive environment prevailing inside the electrolytic cell 10 and will not be detailed here.

[0056] The anode 12a can be a plate pierced with holes, a net, a grid, an expanded metal plate, metal wool, etc. allowing the flow of the electrolyte and the evacuation of gas bubbles.

[0057] The cathode 12b can be a plate pierced with holes, a net, a grid, an expanded metal plate, metal wool, etc. allowing the flow of the electrolyte and the evacuation of gas bubbles.

[0058] The anode 12a and the cathode 12b may be completely identical to each other or different from each other. For example, it is possible to provide different materials and / or coatings for the anode 12a and the cathode 12b depending on the products with which the anode 12a and the cathode 12b are intended to be in contact, the chemical reactions involved, the operating conditions, etc.

[0059] The spacer 16a and the spacer 16b have identical shapes to each other and are for example each formed from a plate of expanded metal, metal wool, corrugated sheet metal, metal foam, etc. allowing the flow of the electrolyte and the evacuation of gas bubbles.

[0060] The interlayer 16a and the interlayer 16b may be completely identical to each other or different from each other. For example, it is possible to provide different materials and / or coatings for the interlayer 16a and the interlayer 16b depending on the products with which the interlayer 16a and the interlayer 16b are intended to be in contact, the chemical reactions involved, the operating conditions, etc.

[0061] According to the invention, said insert 16a has a thickness generally greater than a thickness of the anode 12a except in peripheral zones 16a' which are crushed and are connected to a periphery of the anode 12a by at least one weld made by resistive autogenous welding so as to form an electrodic unit 1216a also called an anode unit. The crushed zones 16a' are here in the form of points, segments (rectilinear or in an arc of a circle) or a mixture of the two. The weld can be continuous or discontinuous and only on the periphery. Alternatively, the crushed zones can comprise, in addition to the points or lines of welding in the peripheral zones, points or lines of welding distributed over the entire surface of the insert 16a so as to uniformize the current distribution over the entire anode 12a.

[0062] According to the invention, said insert 16b has a thickness generally greater than a thickness of the cathode 12b except in peripheral zones 16b' which are crushed and are connected to a periphery of the cathode 12b by at least one weld made by resistive autogenous welding so as to form an electrodic unit 1216b also called cathodic unit. The crushed zones 16b' are here in the form of points, segments (rectilinear or in an arc of a circle) or a mixture of the two. The weld can be continuous or discontinuous and only on the periphery. Alternatively, the crushed zones can comprise, in addition to the points or lines of welding in the peripheral zones, points or lines of welding distributed over the entire surface of the insert 16b so as to uniformize the current distribution over the entire anode 12b.

[0063] To form an electrolytic cell 10, two bipolar plates 14 are pressed against each other so that the bipolar plates 14 delimit between them an internal volume whose peripheral sealing is ensured by the sealing gasket 13 clamped between the rings 142 of the two bipolar plates 14.

[0064] This internal volume is divided in two by the membrane 11 on a first side of which is the anode unit 1216a whose insert 16a bears against the first face of the central web 141 of a first of the two bipolar plates 14; and on a second side of which is the cathode unit 1216b whose insert 16b bears against the second face of the central web 141 of a second of the two bipolar plates 14. Each insert 16a, 16b is elastically deformable in a direction normal to the electrodes 12a, 12b and exerts pressure on the central web 141 and on the electrodes 12a, 12b.

[0065] The central veil 141 plays the role of current collector and exchanges said current with the electrodic units 1216a, 1216b which are on either side of the latter 141.

[0066] Furthermore, the bipolar plate 14 comprises conduits which pass through it from one side to the other and which are dedicated to supplying electrolytic solution to the internal volume of the electrolytic cell 10 and to escaping the electrolysis products from the internal volume of the electrolytic cell 10.

[0067] It should be noted that within the electrolyser stack 1, all the bipolar plates 14 are separated two by two by a seal 13 and that each bipolar plate 14 plays the role of cathode for an electrolytic cell 10 and anode for another electrolytic cell 10 immediately adjacent.

[0068] We will now describe the manufacture of the electrolyzer stack 1.

[0069] Firstly, the unit components (membrane 11, electrodes 12a and 12b, spacers 16a, 16b, bipolar plates 14, sealing gaskets 13) are manufactured in a manner known per se.

[0070] According to the invention, during a second stage, the electrode units 1216a and 1216b are produced. It is recalled that each electrode unit 1216a, 1216b is made up of an interlayer 16a, 16b and an electrode 12a, 12b.

[0071] With reference to figures 3a to 3f, each electrodic unit 1216a, 1216b is made of: - depositing an electrode 12a, 12b on a welding frame B ([Fig.3a]): - depositing an interlayer 16a, 16b on the electrode 12a, 12b ([Fig.3b]); - locally crushing the edge of the insert 16a, 16b at the location of the crushed areas 16a', 16b' using punches P ([Fig.3c]); - locally welding the perimeter of the spacer 16a, 16b at the location of the crushed zones 16a', 16b' using at least one welding head S ([Fig.3d]); - cutting together the interlayer 16a, 16b and the electrode 12a, 12b to the final dimensions of the electrodic unit 1216a, 1216b using for example a laser beam D projected by a laser transmitter or any other cutting tool ([Fig.3e]); - removing the electrodic unit 1216a, 1216b from the welding frame B ([Fig.3f]).

[0072] The welding is carried out by a resistive autogenous welding process. The welding parameters are determined to fix the wires of the electrodes and the interlayer together, limiting if possible the fusion of the wires to the strict minimum to have a fixing strength sufficient to allow manual and automated handling of the assembly thus formed without this causing any significant loss of wires.

[0073] It is possible to provide before welding: - a step of cleaning the electrode 12a, 12b and / or the insert 16a, 16b in the areas to be welded so as to promote welding; and / or - a step of stripping the electrode 12a, 12b and / or the insert 16a, 16b in the areas to be welded in order to remove the surface layer thereof so as to promote welding.

[0074] This cleaning and / or stripping can be carried out, for example, using a laser.

[0075] The electrodic unit thus produced can be used directly to carry out the assembly of the electrolyser stack 1 as described below.

[0076] We will now describe the assembly of the electrolyser stack 1 produced in a third stage of the manufacturing process.

[0077] According to a first step, a bipolar plate 14, an anode unit 1216a with the interlayer 16a resting against the central web 141 of said bipolar plate 14, a membrane 11, a cathode unit 1216b with the cathode 12b oriented towards the membrane 11, a bipolar plate 14 and so on are stacked successively on a first bottom plate 3 and a first distribution plate 5 to form joined electrolytic cells 10.

[0078] In a second step, the last electrolytic cell 10 is covered by the second distribution plate 6, itself covered by the second bottom plate 4, thus delimiting the electrolyser stack 1.

[0079] During a third step, the newly assembled electrolyser stack 1 is put into compression using the tie rods 7, nuts 8 and spring washers 9.

[0080] Such an assembly with thick distribution plates 5 and 6 and thin, flat bipolar plates 14 allows homogeneity of the current in all the electrolytic cells 10 of the electrolyser stack 1 while the voltage is different. at the terminals of each electrolytic cell 10 and that the current is distributed only to one or more points on the periphery of each distribution plate 5 and 6.

[0081] Furthermore, the bipolar plates 14 are indeed parallel to each other within the block. 2 thanks to their particular shape and the good tightening of each sealing joint 13. This further improves the homogeneity of the current in all the electrolytic cells 10.

[0082] The assembly process must ideally allow in particular for each sealing joint 13:

[0083] - to deform according to the geometry imposed by the bipolar plates 14 enclosing it,

[0084] - to bring its material into a range of elastic behavior (centered on an operating point of the electrolyser stack 1),

[0085] - to achieve the desired tightening value combining the desired seals as well as the electrical contacts between the different components allowing the envisaged energy performances to be achieved.

[0086] The nominal operating point of the electrolyser stack 1 is for example 85 degrees Celsius under 3 Megapascals.

[0087] Alternatively, it is possible to constitute a pre-assembly comprising a bipolar plate 14, an anode unit 1216a and a cathode unit 1216b as shown in [Fig.4],

[0088] In this pre-assembly: - the central part of the spacer 16a of the anode unit 1216a bears against the first face of the central web 141 of the bipolar plate 14 and the periphery of the spacer 16a of the anode unit 1216a is welded (for example by resistive or laser welding) against the first face of the ring 142 of the bipolar plate 14 by compressing the central part of the spacer 16a; and - the central part of the spacer 16b of the cathode unit 1216b bears against the second face of the central web 141 of the bipolar plate 14 and the periphery of the spacer 16b of the cathode unit 1216b is welded (for example by resistive or laser welding) against the second face of the ring 142 of the bipolar plate 14 by compressing the central part of the spacer 16b.

[0089] It is understood that the central part of the spacers 16a, 16b has a thickness greater than the thickness of the crushed zones 16a', 16b' and the thickness of the anode 12a and the cathode 12b.

[0090] The pre-assemblies thus produced can then be stacked with membranes 11 to form a block 2 of electrolytic cells 10.

[0091] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0092] The end seal(s) may be different from the sealing gaskets 13.

[0093] The electrolyzer stack 1 may be assembled differently from what has been described.

[0094] The electrolyser stack 1 can be used horizontally, vertically or in a completely different position. The electrolyser stack 1 may be assembled horizontally, vertically or in any other position. Preferably, the electrolyser stack 1 will be assembled vertically and used horizontally.

[0095] It will be possible to have only one conduit associated with the supply of the electrolytic solution and a single conduit associated with the evacuation of each electrolysis product. However, it will be preferable to have two conduits associated with the supply of the electrolytic solution and / or two conduits associated with the evacuation of each electrolysis product for reasons of redundancy in the event that one of the conduits becomes blocked. In general, the distribution plate 5, 6 may have only one conduit opening at each of its ends onto a respective one of the main faces of the distribution plate 5, 6.

[0096] In the same way, it will be preferable to have two grooves associated with each end of each conduit to communicate with the internal volume of the electrolytic cells 10, for reasons of redundancy.

[0097] The different conduits may not be identical to each other.

[0098] The two distribution plates 5 and 6 each associated with one end of block 2 may be different and not identical to each other as mentioned above.

[0099] For example, the distribution plate 5, 6 may comprise at least one conduit opening at least at one of its ends into a recess in said distribution plate 5, 6. Optionally, the conduit will open at least at one of its ends at a position sufficiently close to the external periphery of one of the main faces to allow complete or almost complete emptying (emptying of a liquid and / or a gas) present in the space between the distribution plate 5, 6 in question and the facing bottom plate 3, 4. Optionally, this conduit may be arranged so as to open at a first end into the recess in the first main face of the distribution plate 5, 6 and to open at a second end into the recess in the second main face of said distribution plate 5, 6 so as to put the two recesses in communication.

[0100] The electrolyzer stack 1 may comprise three electrodes 12, namely two end cathodes 12b and a central anode 12a.

[0101] The spring washers 9 can be placed at both ends of the tie rod 7 or at just one of these ends and / or be replaced by any elastic compression member.

[0102] The crushing and welding of the perimeter areas can be carried out simultaneously or successively (in this order).

[0103] It is possible to crush the insert 16a, 16b over its entire circumference and then to weld it to the electrode 12a, 12b only over portions of this circumference or over its entire length.

[0104] In the method described, the welding is followed by an operation of sizing the electrode unit by cutting the perimeter thereof. This operation is optional: the spacer 16a, 16b and the electrode 12a, 12b may have their final dimensions before being welded to each other. However, this requires the spacer 16a, 16b to be properly centered relative to the electrode 12a, 12b before crushing the perimeter zones of the spacer 16a, 16b and welding these to the electrode 12a, 12b.

[0105] The cleaning and / or stripping may concern the electrode 12a, 12b and / or the insert 16a, 16b, in its entirety or only in the areas to be welded.

[0106] Each electrolytic cell 10 may comprise only one electrodic unit formed according to the invention.

[0107] The spacers 16a 16b and the electrodes 12a and 12b typically have circular flat shapes. Of course, other shapes are possible, including square, rectangular, hexagonal, etc.

Claims

Claims

1. Electrode unit (1216) for an electrolytic cell (10), a planar electrode (12) and an interlayer (16) which is elastically deformable in a direction normal to the planar electrode (12) and which has a thickness greater than a thickness of the electrode (12) at least in a central zone of the interlayer (16), the interlayer (16) comprising peripheral zones crushed in said direction and connected to a periphery of the electrode (12) by a weld carried out by resistive autogenous welding.

2. The electrodic unit (1216) of claim 1, wherein the perimeter areas comprise at least one point-shaped area.

3. An electrodic unit (1216) according to claim 1 or 2, wherein the perimeter areas comprise at least one segment-shaped area.

4. An electrolytic cell (10) comprising at least a first and a second bipolar plate (14), an electrode unit (1216) adjacent to each bipolar plate and a membrane (11) between the electrode units (1216), the electrode units (1216) being in accordance with any one of the preceding claims and forming for one an anode and for the other a cathode.

5. Electrolyzer stack comprising two base plates (3, 4) enclosing a stack of elements (2) comprising electrolytic cells (10), each electrolytic cell (10) being in accordance with the preceding claim.

6. Method for manufacturing an electrolyser stack (1) according to the preceding claim, comprising a phase of stacking bipolar plates (14), electrodic units (1216) and membranes (11), and, prior to stacking, a phase of producing the electrodic units (1216) comprising the steps of crushing peripheral zones of the interlayer (16) and welding the crushed zones to a periphery of the electrode (12) by resistive autogenous welding.

7. A method according to claim 6, wherein the crushing and welding of the perimeter areas are carried out simultaneously.

8. Method according to claim 6 or 7, in which the phase of producing the electrodic units (1216) is preceded by a cleaning at least one of the electrode (12) and the interlayer (16) at least in the areas to be welded.

9. Method according to claim 6 or 7, in which the phase of producing the electrodic units (1216) is preceded by stripping at least one of the electrode (12) and the interlayer (16) at least in the areas to be welded.

10. Method according to any one of claims 6 to 9, in which the welding is followed by an operation of sizing the electrodic unit (1216) by cutting the perimeter thereof.

11. A method according to any one of claims 6 to 10, wherein the production of the electrodic units (1216) is followed by a pre-assembly operation comprising the fixing of at least one electrodic unit (1216) on each bipolar plate (14).

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