Bipolar plates, electrolytic cells, electrolytic cell stacks, and related assembly methods

Abstract

The present invention relates to a bipolar plate for an electrolytic cell, the plate comprising, on at least one of its main faces, a first circumferentially extending zone, a second circumferentially extending zone bounded outwardly by the first zone, and a third circumferentially extending zone bounded outwardly by the second zone, the various zones being arranged on the periphery of the associated main face. The invention also relates to corresponding cells, electrolyzer cells, and methods of assembly.

Description

[Technical Field]

[0001] The present invention relates to a bipolar plate.

[0002] The present invention relates to an electrolysis cell comprising such a plate.

[0003] The invention also relates to an electrolyzer stack comprising such an electrolysis cell.

[0004] The present invention also relates to a method for assembling such an electrolyzer stack. [Background technology]

[0005] The general construction of an electrolyzer stack usually consists of blocks of electrolysis cells stacked in series from an electrical point of view and in parallel from a fluidic point of view, and a seal.

[0006] The purpose of each electrolysis cell is to facilitate the electrolysis of an electrolyte solution (alkaline water, purified water, unpurified water, salt, aqueous chloride solution, aqueous bromide solution, aqueous hydrochloric acid solution, etc.) For example, the function of an electrolyzer stack is to facilitate the reaction to produce dihydrogen (H2) and dioxygen (O2) gases resulting from the dissociation of water after passing a direct current through an alkaline solution, typically potassium hydroxide (KOH) or sodium hydroxide (NaOH).

[0007] Each electrolysis cell, considered to be primarily metallic conductive parts (although some parts may be non-metallic), generally consists of two bipolar plates adjacent to two inserts (more commonly known as flow field materials), which in turn are generally adjacent to two electrodes in the form of metal plates or grilles or meshes. In the case of alkaline electrolyzer stacks, the electrodes are generally made from nickel. The two electrodes (cathode and anode) are separated by a membrane (also called a diaphragm or porous separator in the case of alkaline electrolyzers), which ensures electrical insulation between the two electrodes, gas separation, and ionic conduction within the electrolysis cell.

[0008] The inserts have two functions: i) to provide a low resistivity metallic path between each bipolar plate and the associated electrode, and ii) to allow for proper circulation of the electrolyte to cool the electrolyzer stack and transport the produced gases.

[0009] The name bipolar plate comes from the fact that all the electrolytic cells are arranged side by side, so bipolar plate N is as follows: - has a higher potential relative to the downstream bipolar plate N+1, so that the bipolar plate N acts as the anode of the electrolytic cell defined by the bipolar plates N and N+1; - has a lower potential relative to the upstream bipolar plate N-1, and bipolar plate N acts as the cathode of the electrolytic cell defined by bipolar plates N-1 and N This comes from the fact that it has the potential to

[0010] In addition to the bipolar plates, other metal parts include the distribution plate (which allows the supply and distribution of electricity to the electrolysis cells) and the base plate (which defines the assembly of the electrolysis cells and makes it possible to fasten said cells together and ensure their sealing).

[0011] In fact, the electrolyzer stack ends with two base plates located immediately before the first electrolytic cell of the stack and immediately after the last electrolytic cell, i.e. one base plate located upstream of the block of electrolytic cells and the other base plate placed downstream thereof with the intention of physically defining the two ends of said block of electrolytic cells.

[0012] The electrolyte present in each electrolytic cell, together with the gases produced by electrolysis (e.g. hydrogen gas, oxygen gas, chlorine gas, halogen gases, etc.), must not leak outside the electrolytic cell in question from the edge of the diaphragm, but must circulate only through dedicated ducts (each duct is dedicated either to the electrolyte alone or to the electrolyte mixed with one of the gases, taking into account that the two gases cannot mix).

[0013] Therefore, the electrolyzer stack cannot operate continuously if a leak is observed, said leak being caused by the electrolyte, the gases produced by electrolysis, or any other substance.

[0014] This means that a variety of problems arise with varying degrees of severity that often have adverse effects on the environment and even on operator safety, which can be associated with significant and potentially irreversible consequences.

[0015] Conventionally, in such electrolysis cells, the assemblies applied to prevent leakage of the electrolyte, one or more gases produced by electrolysis, and / or any other substance from the edge of the diaphragm of the electrolysis cell to the exterior of the electrolysis cell are based on the use of thin seals in the form of sheets, often elastomeric, or O-rings, positioned between the anode and the cathode or membrane of the electrolysis cell, or directly between two adjacent bipolar plates, so that the diaphragm is sandwiched between these different sealing elements.

[0016] Although these seals have good sealing properties, they can be impaired by the phenomenon of creep, which can be more or less severe depending on the quality and composition of the materials used. As a result, when such seals are used, the sealing of the electrolyzer stack (and more particularly within each electrolysis cell) usually eventually deteriorates. Furthermore, this creep phenomenon occurs even more rapidly when one of the influencing factors, such as temperature, has an undesirable effect on the seal in question. Summary of the Invention

[0017] One object of the invention is to propose a solution that makes it possible to guarantee good long-term sealing of the electrolyzer stack. [Means for solving the problem]

[0018] To this end, the present invention relates to a bipolar plate for an electrolytic cell, which plate has, on at least one of its main faces, a circumferentially extending first zone; a second zone extending in the circumferential direction so as to be bordered on the outside by the first zone, the second zone defining at least one narrowing in the thickness of the plate; a third zone extending circumferentially so as to be bordered on the outside by the second zone, the third zone defining at least one narrowing in the thickness of the plate; wherein the different zones are arranged on the periphery of the associated major surface.

[0019] The invention therefore cleverly has different zones that each make it possible to ensure a specific sealing by a different component outside the bipolar plate (gas circulation duct, membrane, another bipolar plate, etc.).

[0020] The inventors have observed in particular that such bipolar plates have the surprising effect of making it possible to very successfully compress seals between one bipolar plate and another, even with seals having simple geometries, such as, by way of non-limiting example, seals in the form of rings, whereby, when such plates are placed in an electrolyzer stack, the sealing of this electrolyzer stack is improved, even in the long term.

[0021] The invention is particularly suitable for use in electrolyzer stacks with large dimensions, where the bipolar plates may have an electrode area of ​​up to several square metres per electrolysis cell.

[0022] Optionally, the narrowing is formed by at least one shoulder between two consecutive zones.

[0023] Optionally, the first zone is textured.

[0024] Optionally, the textured first zone also extends circumferentially on another of the major surfaces of the bipolar plate.

[0025] Optionally, the second zone and / or the third zone are non-textured.

[0026] Optionally, the bipolar plate has a rounded periphery.

[0027] Optionally, the first zone comprises grooves.

[0028] Optionally, the second zone and the third zone form at least two shoulders therebetween to provide a narrowing of the thickness of the plate.

[0029] Optionally, at least three orifices are formed in the second zone.

[0030] The invention also relates to an electrolysis cell comprising at least a first bipolar plate as described above, at least a second bipolar plate as described above, and a single seal arranged between the two bipolar plates.

[0031] Optionally, the seal is made from a monomeric or polymeric material.

[0032] Optionally, the seal is in the shape of a flat ring.

[0033] Optionally, the seal is made from a glass fiber reinforced material and / or a carbon fiber reinforced material.

[0034] The present invention also relates to an electrolyzer stack comprising a plurality of such electrolysis cells.

[0035] The present invention also relates to a method for assembling an electrolyzer stack as described above, which method comprises the steps of: - individually assembling a set of electrolytic half-cells; - combining sets of electrolytic half-cells and placing seals between each set to form a block; - subjecting the block to successive heating and cooling phases and subjecting the block to at least one clamping action between two different heating and cooling phases; Includes.

[0036] Optionally, the block is heated by injecting steam or hot water into the block to effect the clamping.

[0037] Other characteristics and advantages of the invention will become apparent on reading the following description of specific, non-limiting embodiments of the invention.

[0038] Reference is made to the accompanying drawings. [Brief explanation of the drawings]

[0039] [Figure 1]FIG. 1 is an exploded schematic view of an electrolysis cell according to one particular embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a bipolar plate of the electrolysis cell shown in FIG. [Figure 3a] FIG. 3a is a cross-sectional view of a portion of the bipolar plate shown in FIG. [Figure 3b] FIG. 3b is a cross-sectional view of a portion of the bipolar plate shown in FIG. 2, also showing the membrane of the electrolysis cell. [Figure 3c] FIG. 3c is a cross-sectional view of a portion of the electrolysis cell shown in FIG. [Figure 4] FIG. 4 is a diagram of an electrolyzer stack comprising electrolysis cells as shown in FIG. [Figure 5] FIG. 5 is a graph showing the average reduction in seal thickness of one of the cells of the electrolyzer stack shown in FIG. 4 upon assembly of said stack. DETAILED DESCRIPTION OF THE INVENTION

[0040] With reference to the various figures, the electrolyzer stack 1 extends elongately in a general direction A.

[0041] The electrolyzer stack 1 comprises a block 2 of electrolytic cells comprising at least two electrolytic cells mounted side by side in a general direction A. Within the block 2, the electrolytic cells are mounted in parallel from a fluidic point of view and in series from an electrical point of view.

[0042] At the two ends (in general direction A) of the block 2, the electrolyzer stack 1 comprises two base plates 3 and 4.

[0043] These base plates 3 and 4 form the support against which the electrolysis cells are compressed so that the electrolyzer stack 1 is sealed and so that high quality electrical contact is made within the electrolysis cells.

[0044] Furthermore, the base plates 3 and 4 make it possible to withstand the forces generated by the pressure inside the block 2 as well as the forces outside the block 2 necessary to ensure its compression.

[0045] The base plates 3 and 4 can act as electrical conductors and current distributors.

[0046] Preferably, the electrolyzer stack 1 comprises a first distribution plate 5 associated with the first base plate 3 and a second distribution plate 6 associated with the second base plate 4. In this case, the distribution plates 5 and 6 act as electrical conductors and current distributors.

[0047] A first distribution plate 5 (associated with the positive terminal) is arranged upstream of the block 2 and a second distribution plate 6 (associated with the negative terminal) is arranged downstream of said block 2 .

[0048] The concepts "upstream" and "downstream" are defined in terms of the direction of circulation of the current through block 2.

[0049] The first of the two distributor plates, 5, is connected to the positive terminal of the electrolyzer stack 1. Therefore, one portion of the inner main surface of the first base plate 3 (the main surface facing towards the block 2, in particular towards the distributor plate 5) is covered with a patch of electrically insulating material, for example, located in the centre of said inner main surface.

[0050] The second of the two distributor plates 6 is connected to the negative terminal of the electrolyzer stack 1. The second base plate 4 is at the same potential and also serves as a bridge for the supply of electrolyte and the discharge of this same solution carrying the gases formed during the electrolysis in block 2.

[0051] Therefore, holes are made in the second base plate 4. The holes often have different cross sections on the two main faces of the second base plate 4. For example, the outer main face (the main face facing the outside of the block 2) is provided with one or two (e.g., cylindrical) holes for supplying the electrolyte and two holes for discharging the heated electrolyte as well as the electrolysis reaction products. For the same purpose, three or four holes are made on the inner main face (opposite the outer main face) of the second base plate 4, e.g., oblong holes for improving fluid distribution or collection. For example, the holes in the outer main face are provided with flanges suitable for connecting electrolyte intake and return hoses.

[0052] Furthermore, here the electrolyzer stack 1 is supplied with direct current.

[0053] For example, the first distribution plate 5 has a potential of about 700 volts, while the second distribution plate 6 has a potential of 0 volts. The supply and discharge of the electrolyte is performed through the second distribution plate 6 and the second base plate 4, and the second distribution plate 6 has a potential of 0 volts, which prevents current leakage (the potential of the second distribution plate 6 is ground potential).

[0054] Within the electrolyzer stack 1, the current passes through the electrolyte through membrane 11, which will be described below. Within block 2 are seals (which will be described below), which are chosen from a material that has a much higher electrical resistance than the electrolyte.

[0055] The electrolyzer stack 1 comprises end seals (not shown) arranged between the first distribution plate 5 and the first base plate 3. The first base plate 3 is earthed so that the potential difference at said end seals reaches the same value as the voltage applied between the positive and negative terminals of the electrolyzer stack 1, for example about 700 volts.

[0056] As a result, the first base plate 3 is electrically insulated from the block 2 .

[0057] For example, the electrolyzer stack 1 comprises a layer (not shown in the figures) made of an electrically insulating material, which layer is arranged between the first base plate 3 and the first distribution plate 5 .

[0058] For example, the layer may be an inserted disc or a deposit made on the first base plate 3 and / or the first distribution plate 5 .

[0059] The electrolyzer stack 1 comprises means for fastening the various electrolysis cells 10 together by clamping together.

[0060] For example, the fastening means comprises a plurality of tie rods 7. Each tie rod 7 extends linearly within the electrolyzer stack 1. Each tie rod 7 therefore extends longitudinally within the electrolyzer stack 1, parallel to the general direction A. Each tie rod 7 is in the form of a shaft.

[0061] The tie rods 7 therefore all extend parallel to one another.

[0062] The tie rods 7 are positioned on the periphery of the various electrolysis cells. Preferably, the tie rods 7 are distributed over the entire circumference of the block 2, preferably at regular intervals.

[0063] The tie rods 7 extend through particular holes in the base plates 3 and 4 of the electrolyzer stack 1 so that each has two ends outside the block 2 .

[0064] Preferably, the tie rods 7 are partially covered with sleeves made of an electrically insulating material, which prevents short circuits between the electrolysis cells in the event of contact or splashing. For example, the sleeve extends over the entire tie rods 7 arranged between the two base plates 3 and 4.

[0065] Preferably, the ends of the tie rods 7 are threaded.

[0066] For example, the threads on the ends are rolled threads, which have the advantage of making machining of the tie rod 7 easier, especially when the tie rod 7 is very long, for example several meters long.

[0067] The fastening means also comprises a nut 8 which is screwed onto the end of the tie rod 7 .

[0068] The nuts 8 make it possible to press together the two base plates 3 and 4 and therefore the various electrolysis cells, which ensures an adequate sealing of the stack of electrolysis cells.

[0069] Preferably, the fastening means also comprise means for prestressing the two base plates 3 and 4 together, and thus for prestressing the various electrolysis cells together. Said prestressing means also make it possible to absorb deformations and / or thickness changes of the components of the electrolyzer stack 1 due to thermal expansion or thermal fluctuations in mechanical stresses inside and outside the electrolyzer stack 1 (e.g. pressure inside the electrolyzer stack).

[0070] The prestressing means is received at the end of the tie rod 7 so that for a given end it is located between the nearest base plate (3 or 4) and a nut 8 located at the same end.

[0071] For example, the fastening means comprises a spring washer 9, such as a Belleville washer. The spring washer 9 is received at the end of the tie rod 7.

[0072] Here, more specifically, a spring washer 9 is positioned on each tie rod 7 at the outer part of said tie rod 7 when said tie rod 7 passes through the nearest base plate (3 or 4).

[0073] The above fastening means enable the electrolyzer stack 1 to withstand thermal expansion and / or thermal fluctuations, in particular mechanical stresses inside and outside the electrolyzer stack 1 (for example pressure inside the electrolyzer stack).

[0074] In the present case, all of the electrolysis cells of the electrolyzer stack 1 are identical to one another, so the following description of one electrolysis cell 10 also applies to the other electrolysis cells 10.

[0075] Such an electrolysis cell 10 comprises a central membrane 11 flanked by two electrodes 12a and 12b (anode and cathode, respectively), which in turn are flanked by two inserts 16 (or flow field materials), which in turn are flanked by two bipolar plates 14. Furthermore, the electrolysis cell 10 also comprises a seal 13 (the presence of which has already been mentioned above) which is compressed between the two bipolar plates 14 of the electrolysis cell 10.

[0076] The membrane 11, insert 16, and electrodes 12a and 12b are known in the prior art and will not be described in detail here.

[0077] The two bipolar plates 14 of the electrolysis cell 10 are identical to each other, and the following description of one of the bipolar plates 14 also applies to the other bipolar plate 14 of the same electrolysis cell 10. The bipolar plates 14 are made from materials that can withstand the corrosive environment prevailing inside the electrolysis cell 10.

[0078] The bipolar plates 14 are, for example, nickel-based and made from, for example, nickel or nickel-carbon steel.

[0079] The bipolar plate 14 is further configured to have two main surfaces, a first main surface facing towards the inside of the electrolysis cell 10 and a second main surface facing towards the outside of the electrolysis cell 10.

[0080] It will be seen below that the bipolar plates 14 are asymmetric (along a plane of symmetry passing through the center of the bipolar plate in question). As a result, within the same electrolysis cell 10, a first side of a bipolar plate 14 being illustrated faces a second side of another bipolar plate 14 that is identical to the one being illustrated. Within block 2, all of the bipolar plates 14 are similarly oriented.

[0081] In the following, axes X and Y are defined which form a plane spanning one of the main faces of the bipolar plate 14, together with axis Z which is perpendicular to said plane XY.

[0082] When the bipolar plate 14 is in place in the electrolysis cell 10, which in turn is in place in the electrolysis cell stack 1, the axis Z now coincides with the general direction A.

[0083] The thickness of the bipolar plate 14 (along axis Z) is smaller than the other dimensions.

[0084] The bipolar plate 14 can be configured to have a cross-section (in the plane XY) of any geometric shape (square, rectangular, disk-shaped, etc.) Here, the bipolar plate has a disk-shaped cross-section.

[0085] The periphery of the bipolar plate 14 is defined by a first zone 21, a second zone 22, and a third zone .

[0086] Here, the first zone 21 extends around the entire periphery of at least one of the main faces of the bipolar plate 14. The first zone 21 is therefore a ring that forms the periphery of the main face.

[0087] The first zone 21 makes it possible to improve the resistance of the bipolar plate 14 to the pressure prevailing inside the electrolyzer stack 1 and to improve the sealing of the electrolysis cell 10 to the outside of the electrolyzer stack 1. In particular, said first zone 21 makes it possible to increase the resistance of the bipolar plate 14 to radial pressure loads exerted on it (when the electrolysis cell 10 is placed in the electrolyzer stack 1). For example, the first zone 21 is designed to comply with standards applicable to pressure vessels, for example standard PED 2014 / 68 / EU.

[0088] The first zone 21 is preferably textured, e.g., the first zone 21 comprises grooves, flutes, irregularities, a roughened appearance, etc. on at least one of the major surfaces of the bipolar plate 14, and preferably on both major surfaces of the bipolar plate 14.

[0089] Conversely, the circular rim of the bipolar plate 14 (ie, the surface connecting the two major faces of the bipolar plate 14 together) is smooth (ie, not textured).

[0090] Furthermore, the second zone 22 extends in the circumferential direction so as to be bounded on the outside by the first zone 21. The second zone 22 is coaxial with the first zone 21.

[0091] Here, the second zone 22 extends around the entire periphery of at least one of the main faces of the bipolar plate 14. The second zone 22 is therefore a ring.

[0092] The second zone 22 is smooth, ie, not textured.

[0093] This second zone 22 is located around a duct for feeding the electrolyte and a duct for discharging the gas products of the electrolysis.

[0094] This second zone 22 is not thicker than the first zone 21 (thickness considered along axis Z). For example, the bipolar plate 14 is configured to have at least one shoulder between the first zone 21 and the second zone 22. Preferably, the bipolar plate 14 is configured to have two shoulders between the first zone 21 and the second zone 22, where these two shoulders are identical (as can be seen in FIG. 3a) and are made on both main faces of the bipolar plate 14.

[0095] The bipolar plate 14 is therefore symmetrical along a central plane of symmetry parallel to the axes X and Y in its first 21 and second 22 zones.

[0096] The narrowing between the first zone 21 and the second zone 22 makes it possible to achieve a different sealing between the two zones.

[0097] Furthermore, the third zone 23 extends in the circumferential direction so as to be bounded on the outside by the second zone 22. The third zone 23 is coaxial with the second zone 22.

[0098] Here, the third zone 23 extends around the entire circumference of the bipolar plate. The third zone 23 is a ring.

[0099] This third zone 23 is not thicker (thickness considered along axis Z) than the second zone 22. For example, the bipolar plate 14 is configured to have at least one shoulder between the second zone 22 and the third zone 23.

[0100] Preferably, the bipolar plate 14 is configured with a single shoulder between the second zone 22 and the third zone 23. This shoulder is made on the first main surface of the bipolar plate 14, i.e. on the main surface facing towards the inside of the electrolysis cell 10. This shoulder makes it possible to accommodate the membrane 11.

[0101] Preferably, the second zone 22 and the third zone 23 extend continuously on the second major surface of the bipolar plate 14 .

[0102] Therefore, there is no shoulder between the second zone 22 and the third zone 23 on the second major surface.

[0103] It will therefore be understood that the second face of the bipolar plate 14 does not have such a shoulder, and therefore the second faces of the other bipolar plates of the electrolysis cell in question do not have such a shoulder, and therefore the membrane 11 is disposed between the two bipolar plates 14 such that it is solely housed on the shoulder of one of the two bipolar plates.

[0104] The bipolar plate 14 is therefore asymmetric along a central plane of symmetry parallel to the axes X and Y when considering the three zones mentioned above (as can be seen most clearly in Figures 3a, 3b and 3c).

[0105] The third zone 23 may be entirely smooth (i.e., not textured), partially smooth, or entirely textured. Preferably, the third zone 23 is textured on the first major surface of the bipolar plate 14. This makes it easier to hold the membrane 11 in place. For example, on the first major surface, the third zone 23 comprises grooves, fluting, bumps, a roughened appearance, etc.

[0106] Preferably, the third zone 23 is smooth on the second major surface of the bipolar plate 14 .

[0107] Thus, the thickness (along axis Z) of the bipolar plate 14 gradually decreases with shoulders at the junction between the first zone 21 and the second zone 22 and at the junction between the second zone 22 and the third zone 23. Thus, the bipolar plate 14 is thicker in its first zone 21 than in its second zone 22, and thicker in its second zone 22 than in its third zone 23.

[0108] The first zone 21, the second zone 22, and the third zone 23 together form a crown 25. The crown 25 therefore forms the periphery of the bipolar plate 14.

[0109] Furthermore, the central portion 24 of the bipolar plate 14 extends so as to be bounded on the outside by the third zone 23. The central portion 24 is coaxial with the third zone 23.

[0110] The central portion 24 is solid and therefore forms a circular platform.

[0111] This central portion 24 is less thick (thickness considered along axis Z) than the third zone 23 .

[0112] For example, the bipolar plate 14 is configured to have at least one shoulder between the third zone 23 and the central portion 24. Preferably, the bipolar plate 14 is configured to have two shoulders between the third zone 23 and the central portion 24, where these two shoulders are identical and are fabricated on both major surfaces of the bipolar plate 14.

[0113] The central portion 24 may then optionally have at least one shoulder so that its thickness (thickness considered along the axis Z) decreases towards the centre of the plate.

[0114] The central portion 24 is therefore the thinnest part of the bipolar plate 14 (thickness considered along the axis Z).

[0115] The central portion 24 may be smooth or textured.

[0116] The central portion 24 acts as a current collector and carries this current to the inserts 16 on either side of it.

[0117] Furthermore, the bipolar plate 14 is provided with orifices 15 passing through it from one side to the other. These orifices 15 are dedicated to the supply of electrolyte and the discharge of the products of electrolysis.

[0118] For example, the bipolar plate 14 may include three to six orifices. For example, the orifices may be associated in pairs, with the sets of two orifices evenly distributed around the periphery of the bipolar plate 14. Thus, the bipolar plate may include three sets of two orifices.

[0119] For example, at least one of the orifices 15 is made in the second zone 22. In the present case, all of the orifices 15 are made in the second zone 22.

[0120] The orifices can have a cross-section that is circular, oblong, or another shape. For example, at least one of the orifices 15 has an oblong cross-section.

[0121] In a manner known per se, one or more further orifices extend from the orifice 15 towards the central part 24 to allow the supply of electrolyte to the interior of the electrolysis cell and the discharge of the products of electrolysis from the interior of the electrolysis cell. For example, these further orifices extend radially. To prevent the seal 13 from blocking the orifice, the orifice is preferably at least partially made on the surface of the bipolar plate 14 and is laterally closed by one or more covers which are then in contact with the seal.

[0122] In fact, the role of said central part 24 is not really to withstand high pressure against the crown part 25. Therefore, the main role of the central part 24 is to act as a support for the components stacked in the electrolysis cell 10, namely the insert 16, the electrodes 12a and 12b and the membrane 11. The forces are therefore equal on the two faces of the central part 24.

[0123] As a result, the bipolar plate 14 has a specific geometric structure, with the thickness of each of the zones varying from another zone by a few tenths to a few millimeters, and the thickness of the zones also having a variable value under the influence of thermal expansion of the bipolar plate 14 (hence the variability of the thickness of each zone due to thermal expansion also varies from one zone to another).

[0124] As already mentioned, within the electrolysis cell 10, two bipolar plates 14 compress the seal 13 between them.

[0125] It should be noted that within the electrolyzer stack 1, all of the bipolar plates 14 are separated in pairs by seals 13 (as each bipolar plate 14 serves as a cathode for one electrolysis cell 10 and an anode for another immediately adjacent electrolysis cell 10).

[0126] Advantageously, the two bipolar plates 14 compress a single seal 13 between them.

[0127] Advantageously, all of the seals 13 of the electrolysis cells 10 are identical within the block 2 of cells, so the following description of one of the seals 13 also applies to the other seals 13 of the other electrolysis cells 10.

[0128] The main functions of the seals 13 are: i) to seal each electrolysis cell 10 against the outside of the electrolyzer stack 1; ii) to seal the ducts carrying one gas produced in block 2 against the ducts carrying another gas produced in block 2; iii) to seal the chambers in which the electrolysis reactions producing the two said gases take place in order to separate them from each other, and also to seal the chambers against the ducts mentioned just before; iv) to act as an electrical insulating layer between two adjacent bipolar plates 14; v) to define the thickness through which the electrolysis cell 10 is compressed in direction Z.

[0129] Advantageously, a single seal 13 is compressed between two adjacent bipolar plates 14 within the same electrolysis cell 10 .

[0130] Preferably, the seal 13 is shaped to have a square or rectangular cross section (along the cross section).

[0131] Therefore, the seal 13 is called a "flat seal."

[0132] Preferably, the seal 13 is shaped to correspond to the shape of the crown 25 of the associated bipolar plate 14 .

[0133] In this case, the seal 13 is generally ring-shaped and the associated bipolar plate 14 is disc-shaped.

[0134] It will be noted that the seal 13 is perforated with a number of holes.

[0135] This allows for the supply and evacuation of fluids to and from the block 2. For example, the holes made in the seal 13 correspond to the holes made in the zone 22 of the bipolar plate 14.

[0136] The seal 13 is configured to have a diameter (of its cross section) that is as constant as possible around all of its inner and outer circumferences, and / or a thickness (along the axis Z) that is as constant as possible over its entire range (and even from one seal 13 to another).

[0137] This makes it possible to improve the efficiency of the electrolysis cells 10 of the electrolyzer stack 1 .

[0138] It makes it possible in particular to have the faces of the seals 13 as parallel as possible to each other and to the main faces of the opposing bipolar plates 14 .

[0139] This further improves the sealing of the assembly.

[0140] The tolerances on the dimensions of the seal 13 depend on its intended use (for example, thickness tolerance is ±0.1 millimeters).

[0141] As already mentioned, and as can be seen more clearly in FIG. 3c, the seal 13 is compressed between two adjacent bipolar plates 14, more particularly between the two outer peripheries of the opposing main faces of said bipolar plates 14, more particularly between the two opposing crowns 25 of said bipolar plates 14.

[0142] Due to the particular geometrical structure of the bipolar plate 14 on its periphery, in particular its crown 25, when the bipolar plate 14 compresses the seal 13, the bipolar plate 14 then deforms the seal 13 in such a way that they define and characterise said seal 13 into three separate parts.

[0143] However, the seal 13 is not compressed between the central portions 24 of the two bipolar plates 14 .

[0144] The diameter of the seal 13 (along the cross section) is such that the seal 13 extends from the side edge of the bipolar plate 14 to the junction between the third zone 23 and the central portion 24 (preferably extending beyond the third zone 23).

[0145] Thus, each portion of the present seal 13 performs a distinct sealing function and is characterized by a specific compression level that varies from one portion to another. The physical and mechanical result is a variable reduction in the thickness of the seal 13 depending on the portion under consideration.

[0146] Thus, when the seal 13 is at rest, the seal 13 has a conventional toroidal shape and a substantially unitary initial thickness.

[0147] When the seal 13 is compressed between the two plates 14, - between the first zones 21 of two bipolar plates 14, the seal 13 follows the geometry of said first zones 21 and therefore has a corresponding textured first portion; between the second zones 22 of the two bipolar plates 14, the seal 13 has a corresponding smooth second portion, which also has a thickness greater than the thickness of its first portion; Between the third zones 23 of the two bipolar plates 14 and the membrane 11, the seal 13 has a corresponding smooth and / or grooved third portion.

[0148] In its first part, the seal 13 is compressed directly between the two first zones 21 (without any intermediate components).

[0149] In its second part, the seal 13 is compressed directly between the two second zones 22 (without any intermediate components).

[0150] However, in its third portion, the seal 13 is not directly compressed between two third zones 23. In fact, there is also a membrane 11 between these two third zones 23. As a result, the seal 13 is directly compressed on one side by one of the third zones 23 and on its other side by the membrane 11, which in turn is directly compressed by the third zone 23 of the opposing bipolar plate 14.

[0151] Furthermore, in its third portion, the seal 13 has a thickness substantially smaller than in its second portion, with the membrane 11 filling the remaining space between the two third zones 23. The membrane 11 is therefore sealed.

[0152] The seal 13 is therefore distributed over its entire height (along the axis X) between its three parts and therefore between the three zones of the crown 25 .

[0153] As a result, the part of the electrolysis cell 10 located in the first zone 21 of the two bipolar plates 14 and in the first part of the seal 13 is dedicated to making it possible to prevent the electrolyte or gas from leaving the electrolyzer stack 1, i.e. to seal the electrolysis cell 10 against the external environment. -3 Leak rate of milligrams per meter per second or less (mg / (m*s) when leak rate is measured using helium gas), preferably 10 -4 Guarantees a leak rate of less than mg / (m*s).

[0154] This first portion is characterized by the presence of a texture on the bipolar plate 14, into which the seal 13 deforms. In particular, the deformation allows the seal 13 to fill the recesses in the first portion of the bipolar plate 14, thus enhancing the sealing of the electrolysis cells 10. This is because these textures form an additional obstacle for gases and other substances present that are seeking a path out of the electrolyzer stack 1. The presence of this texture also serves to promote friction between the electrolysis cells 10 and, therefore, the self-retaining ability of multiple electrolysis cells 10 stacked to form the block 2. This advantage is increased if the block is horizontal during operation.

[0155] For example, the compression of the seal 13 is such that the seal 13 reaches a maximum thickness (along axis Z) in the first portion (when the seal 13 is in a resting state lying flat on a flat surface without external stress) of 94%, preferably 78%, preferably 75% of its initial thickness. The initial thickness is, for example, 3.0 millimeters or more. Preferably, this initial thickness is 3.5 millimeters or less.

[0156] The second part of the electrolysis cell 10, located in the second zone 22 of the two bipolar plates 14 and in the second part of the seal 13, makes it possible to prevent exchange between the ducts carrying hydrogen and oxygen within the electrolysis cell 10 or from the electrolysis cell 10 itself (starting from the third zone 23 and the central part 24) to said ducts.

[0157] For example, the compression of seal 13 is such that seal 13 reaches a thickness (along axis Z) at the second portion that is 92-97% of its initial thickness (when seal 13 is in a resting state lying flat on a flat surface without external stress), preferably 92% of its initial thickness. In any case, seal 13 is less compressed than at the first portion and therefore has a greater thickness than at the first portion.

[0158] The extension of the seal 13 between the first zone 21 and the second zone 22 allows for the realization of a different sealing between the first zone 21 and the second zone 22. In particular, the sealing between the first zone 21 and the second zone 22 is of high quality.

[0159] The third part of the electrolysis cell 10, located in the third zone 23 of the two bipolar plates 14 and in the third part of the seal 13, makes it possible to receive the membrane 11, as already mentioned.

[0160] This third part therefore ensures sealing between the anode and cathode compartments of the electrolysis cell 10 .

[0161] It will therefore be noted that in that case, both the membrane 11 and the seal 13 are compressed between the two bipolar plates 14 in this third portion. The seal 13 is therefore superimposed on the membrane 11 in this portion of the electrolysis cell 10.

[0162] This ensures a very good seal around the membrane 11 on its periphery towards the fluid supply and discharge ducts.

[0163] The third part of the seal 13 therefore defines a third compression zone intended to hold the membrane 11 and seal its periphery.

[0164] For example, the compression of the seal 13 is such that the seal 13 reaches a thickness (along axis Z) in the third portion that is 86 to 92% of its initial thickness (when the seal 13 is in a resting state lying flat on a flat surface without external stress), preferably 88 to 92% of its initial thickness, preferably 90% of its initial thickness.

[0165] According to another embodiment, the seal 13 is made from a monomeric or polymeric material, for example from a plastic material.

[0166] For example, the seal 13 is made from a polytetrafluoroethylene or polytetrafluoroethene type material (commonly abbreviated as PTFE or better known by its trade name Teflon®).

[0167] Preferably, the material is made from, based on or made of polytetrafluoroethylene or polytetrafluoroethene type to which at least one filler is added, for example glass fiber.

[0168] The material is, for example, reinforced polytetrafluoroethylene, which is, for example, glass-fiber reinforced polytetrafluoroethylene, or reinforced polytetrafluoroethene, which is, for example, carbon-fiber reinforced polytetrafluoroethene.

[0169] The characteristics of the described seal 13 are defined below. - Good long-term behavior of the material and retention of its good mechanical properties at significant electrolysis cell 10 operating temperatures (typically around 90-95 degrees Celsius). - Long-term resistance to the corrosive environment inside the electrolysis cell 10. - Good sealing properties. - Good electrical insulation (provided by good electrical resistance) (even at operating temperatures and in contact with the electrolyte). - low creep allowing a good service life of the stack of electrolysis cells 10; However, a slight creep behavior in order to conform as closely as possible to the geometric features of the zone 21 in which the seal 13 is seated. - uniform thickness (along axis Z).

[0170] According to one option, the edge seals arranged between the first distributor plate 5 and the first base plate 3 are made from the same material as the seals 13 of the electrolysis cell 10 as described above. The edge seals are, for example, identical to said seals 13. Said edge seals are optionally made from a monomeric or polymeric material, for example from a plastic material.

[0171] According to one option, the layer made of electrically insulating material between the first base plate 3 and the first distribution plate 5 is made of the same material as the edge seals arranged between the first distribution plate 5 and the first base plate 3. According to one option, the layer made of electrically insulating material between the first base plate 3 and the first distribution plate 5 is made of the same material as said seals 13. Said layer is optionally made of a monomeric or polymeric material, for example a plastic material.

[0172] According to one option, the edge seals arranged between the second distributor plate 6 and the second base plate 4 are made from the same material as the seals 13 of the electrolysis cell 10 as described above. Said edge seals are, for example, identical to said seals 13. Said edge seals are optionally made from a monomeric or polymeric material, for example from a plastic material.

[0173] According to one option, the patch placed on the inner surface of the first distribution plate 5 is a layer of material attached directly to the first distribution plate 5 or is formed by powder coating (e.g. by Halar® coating).

[0174] The described electrolysis cell 10 therefore has a very good sealing due to the particular compression of the seal 13 between the bipolar plates 14 .

[0175] It will further be noted that the electrolysis cell 10 is sealed by a single seal 13 having three distinct sealing and compression zones.

[0176] The use of a single seal 13 made from plastic (and not elastomer as in the prior art) also makes it possible to improve the sealing of the electrolyzer stack.

[0177] This is because the seal 13 better withstands the corrosive environment prevailing inside the electrolyzer stack 1, even over the long term.

[0178] The seal 13 is therefore made from a hard material that can withstand the large mechanical compression to which the electrolyzer stack is subjected.

[0179] A method for assembling the electrolyzer stack 1 will now be described.

[0180] According to a first step, the subassemblies are constructed individually, each subassembly being formed by combining two inserts 16 and two electrodes 12a, 12b on either side of a bipolar plate 14. Strictly speaking, each subassembly forms two electrolytic half-cells placed side by side.

[0181] In a second step, the subassemblies are stacked in succession, separated from one another by membranes 11 and seals 13, to form the electrolysis cells 10, electrically connected in series. The last electrolysis cell 10 at one end of the block 2 is covered by a second distribution plate 6 which is then covered by a second base plate 4, and the last electrolysis cell 10 at the other end of the block 2 is covered by a first distribution plate 5 which is then covered by a first base plate 3, thus defining the electrolyzer stack 1.

[0182] During a third step, the newly assembled electrolyzer stack 1 is compressed by tie rods 7 , nuts 8 and spring washers 9 .

[0183] For this purpose, a pre-clamping of the electrolyzer stack 1 (and therefore of the various layers of the electrolysis cell 10 and the seals 13 together) is carried out.

[0184] This third step is preferably carried out at ambient temperature, for example, this third step is carried out at a temperature of 15 to 25 degrees Celsius, for example 18 to 22 degrees Celsius.

[0185] Pre-tightening is obtained, for example, by the action of the tie rod 7 on the nuts 8. Preferably, several nuts 8 are tightened simultaneously. Preferably, all nuts 8 are divided into groups, each group being tightened in turn, with nuts of the same group being tightened simultaneously. Preferably, the groups are tightened in a staggered or star-shaped sequence. One group of nuts 8 can, for example, be tightened simultaneously before moving on to the next group, which is located as close as possible to the nuts 8 of the first group, etc. Preferably, all of the nuts 8 are tightened during this phase.

[0186] Thus, during the third step, several nuts 8 act simultaneously, but not all of the nuts 8 of a block are tightened at the same time.

[0187] This helps ensure that the thickness of the seal 13 is reduced relatively evenly and uniformly around the circumference of the various seals.

[0188] Pre-tightening can be carried out, for example, using hydraulic means, for example a hydraulic cylinder.

[0189] During this third step, the electrolyzer stack is preferably tightened to reach the desired initial compression ratio threshold characteristic of at least one of the seals 13, and preferably all of the seals 13.

[0190] This threshold may be defined, for example, based on at least one of the following conditions: - at the end of the first phase, at least one of the seals (preferably all of the seals 13) must ensure contact between the two bipolar plates 14 and the membrane 11 in a given cell, and / or At the end of the first phase, at least one of the seals (preferably all of the seals 13) must have a compression ratio of 25-50% of the desired final compression ratio of at least one of the seals 13, and preferably all of the seals 13.

[0191] The threshold value can therefore be a target thickness of at least one of the seals, or a target thickness of the seals, or a target thickness of the electrolytic cell stack 1, or a target clamping torque of the electrolytic cell stack. To estimate whether the clamping is close to the threshold value, for example, during the first phase the thickness of at least one of the seals, or the thickness of the electrolytic cell stack, or the clamping torque applied to the electrolytic cell stack is correspondingly measured.

[0192] In particular, this third step comprises a series of tightening sessions in which the electrolyzer stack is tightened in stages, preferably at the end of each stage the distance from a threshold is estimated in order to control the tightening torque of the next stage.

[0193] Then, during a fourth step, the electrolyzer stack 1, and therefore the block 2, undergoes successive clamping cycles.

[0194] The tightening cycle includes the following phases:

[0195] First phase: heating of electrolyzer stack 1. For example, this first phase is performed by injecting a gas or liquid (such as steam, e.g., water vapor, or a warm liquid, e.g., hot water) through some of the inlet and outlet orifices in the base plate 4 in order to heat the entire interior of the electrolyzer stack 1, and in particular the seals 13. Alternatively, the gas or liquid may be at the ambient temperature inside the electrolyzer stack. For example, heating means may be temporarily introduced into the electrolyzer stack 1 in order to heat the gas or liquid (e.g., the heating means may comprise one or more resistors). Optionally, the heating means is temporarily introduced into the electrolyzer stack 1 through the orifices 15 in the bipolar plate 14.

[0196] Second phase: tightening of the electrolyzer stack 1 (and therefore the various layers of the electrolysis cell 10, and the seals 13). Tightening is obtained, for example, by the action of the tie rod 7 on the nuts 8. Preferably, several nuts 8 are tightened simultaneously. Preferably, all nuts 8 are divided into groups, each group being tightened in turn, with the nuts of the same group being tightened simultaneously. Preferably, the groups are tightened in a staggered or star-shaped sequence. One group of nuts 8 can, for example, be tightened simultaneously before moving on to the next group, which is located as close as possible to the nuts 8 of the first group, etc. Preferably, all of the nuts 8 are tightened during this phase.

[0197] Thus, during the second phase, several nuts 8 act simultaneously, but not all of the nuts 8 of a block are tightened at the same time.

[0198] This helps ensure that the thickness of the seal 13 is reduced relatively evenly and uniformly around the circumference of the various seals.

[0199] The clamping can be performed, for example, using hydraulic means, for example a hydraulic cylinder.

[0200] It will be appreciated that tightening is carried out at an elevated temperature for the previous phase, rather than at ambient temperature as in the third step.

[0201] Third phase: Cooling of electrolyzer stack 1. This cooling can be natural cooling (by turning off the heating of the electrolyzer stack 1, in fact by contact with air at ambient temperature, allowing it to cool naturally) and / or forced cooling (for example by injecting / blowing air with / etc. a gas or liquid (for example cold water) through some of the inlet and outlet orifices of the base plate 4 in order to cool the entire interior of the electrolyzer stack 1, in particular the seals 13).

[0202] Fourth phase: tightening of the electrolyzer stack 1 and therefore the various layers of the electrolysis cell 10 and the seals 13. This tightening is carried out like the second phase, but at ambient temperature like the third pre-tightening step (the temperature ranges given may also apply here).

[0203] Thus, during the fourth step, a series of clamping operations is performed at high temperature and then at ambient temperature on the electrolyzer stack 1 and thus on block 2. Given that clamping at high temperature is performed at a higher temperature than clamping at ambient temperature, it can also be said that a series of clamping operations is performed at high temperature and then at low temperature on the electrolyzer stack 1 and thus on block 2.

[0204] The second phase (especially the first repetition if phases 1 to 4 are repeated several times) allows a significant reduction in the individual thickness of the various seals 13.

[0205] Phases 1-4 are preferably further repeated until a threshold value characteristic of the desired final compression ratio of at least one of the seals 13, preferably all of the seals 13, is reached.

[0206] The threshold can be defined, for example, by considering the following: the desired sealing performance of at least one of the seals 13, preferably all of the seals, and preferably of the electrolyzer stack 1 as a whole; and / or a desired geometric compression of the electrolyzer stack 1 so that the electrical contact is good to achieve a given power output and / or a given electrical continuity, and / or a desired mechanical stability of the material forming the seal or seals 13, so that creep phenomena do not excessively impair the sealing of the electrolyzer stack 1;

[0207] Preferably, said threshold value relates to the compression ratio of at least one of the seals 13, preferably at least one of all of the seals 13.

[0208] Preferably, said threshold value relates to at least the compression ratio of the portion of at least one of the seals 13 (preferably all of the seals 13 ) associated with the first zone 21 of the opposing bipolar plate 14 .

[0209] Even more particularly, said threshold value relates to the compression ratio defined above relating to at least one of the seals, and preferably to all the different portions of the seal 13 .

[0210] It should be noted that at the first iteration, the seals 13 have thicknesses close to their target values, so subsequent iterations are further aimed at eliminating plastic behavior in the seal's operating range.

[0211] Preferably, after each clamping phase (second and fourth phase) at least one of the following parameters is measured: thickness of at least one of the seals, thickness of the electrolyzer stack or block, distance between the base plates 3 and 4, and clamping torque applied to the electrolyzer stack 1. For example, after each clamping phase all thicknesses of the seals 13 are estimated by measuring the distance between the base plates 3 and 4 or the clamping torque applied to the electrolyzer stack 1.

[0212] Step 1. This allows the repetition of phases 1 to 4 to be controlled by estimating the progress towards the final threshold. For example, the final threshold is a target thickness value for the electrolytic cell stack 1. For example, after each tightening phase, the thickness of the electrolytic cell stack 1 is checked. Optionally, the thickness of block 2 is measured by measuring the thickness between base plates 3 and 4 at different points around the periphery of block 2. The average of the different values ​​obtained is then found to obtain the average thickness of block 2. Based on the number of cells and the thicknesses of the different elements per cell, an average thickness for each of the seals 13 is derived. From this, the ratio Hn+1 / Hn is derived, where Hn is the change in thickness that must be achieved to reach the target thickness (here, the final threshold) after the tightening phase just performed, and Hn+1 is the change in thickness that must be achieved to reach this target thickness during the next tightening phase. This ratio makes it possible to monitor the progress of the fourth step. Preferably, the fourth step is performed so that this ratio is maintained within a predetermined range throughout the fourth step. Preferably, when the second phase is performed for the first time, a ratio Hn+1 / Hn of less than 0.5 (meaning that the thickness change has been reduced by more than 50%), preferably less than 0.4 (meaning that the thickness change has been reduced by more than 60%) is aimed for, for example, a ratio Hn+1 / Hn of 0.5 to 0.25, preferably 0.4 to 0.25 is aimed for.

[0213] Step 2. This makes it possible to estimate zones of the electrolyzer stack 1 that have an abnormally greater thickness than other zones of the stack. It is then possible to adapt the tightening during the next tightening phase by targeting nuts that must be tightened preferentially to accommodate zones that are abnormally thicker than other zones of the electrolyzer stack 1. Thus, any lack of parallelism between the bipolar plates 14 and / or between the cells can be corrected during the various tightening phases. This is important to ultimately ensure good electrical contact between the various electrolyzer cells 5 on all surfaces of the cells. This also makes it possible to keep the electrolyzer stack 1 as straight and centered as possible on its axis Z. This also makes it possible to precisely align the base plates 3 and 4 and make them parallel to each other. For example, the inventors observed that the lack of parallelism between the base plates 3 and 4 was less than 1 millimeter for an electrolyzer stack 5 meters long (along the axis Z).

[0214] Preferably, the first procedure and / or the second procedure are also performed for the third pre-tightening step.

[0215] Preferably, the seal 13 is heated using steam (by applying steam). This makes it possible to transfer a large amount of energy to a small amount of fluid corresponding to the size of the duct. Even more particularly, the thickness of the seal 13 is permanently reduced in order to reach a predefined compression ratio. Furthermore, the plastic behavior (or creep) of said seal 13 decreases over the course of the high temperature and ambient temperature tightening cycles until it reaches an elastic behavior range. As a result, at the end of this fourth step, the seal 13 exhibits a linear deformation behavior. This behavior makes it possible to ensure the sealing of the various zones of the bipolar plate 14 (due to the counterbalancing forces caused by the spring washers 9), in particular taking into account the expansions and pressures applied to the electrolyzer stack 1.

[0216] Thus, the plastic nature of the seal 13 is eliminated.

[0217] The thickness (along axis Z) of seal 13 is therefore gradually but significantly reduced by plastic deformation of said seal 13. Figure 5 illustrates this reduction in the thickness of seal 13 during the various steps and phases of the described assembly method. The curves therefore show the change in the average thickness of seal 13 (measured as described above or by another method) during the different steps and phases of the described assembly method, with a value of 100% corresponding to the target thickness reduction.

[0218] For example, over at least some portions of the seal 13, the thickness of the seal 13 is reduced by at least 10%, or at least 15%, or at least 20%, or at least 25%.

[0219] This makes it possible to limit creep of the seal 13 during actual operation of the electrolyzer stack 1 .

[0220] As a result, the seal 13 ensures very good sealing of the electrolyzer stack 1 even over times on the scale of 10 or 20 years.

[0221] Part of the clamping is engineered at high temperatures, which makes it possible to take advantage of the softer (less rigid) nature of the material of the seal 13 at high temperatures.

[0222] Such an assembly of thick distribution plates 5 and 6 and thin flat bipolar plates 14 allows uniformity of the current in all of the electrolysis cells 10 of the electrolyzer stack 1 when the voltage is different at the terminals of each electrolysis cell 10 and the current is connected only to one or more points on the periphery of each distribution plate 5 and 6.

[0223] Furthermore, the bipolar plates 14 are parallel to each other within the block 2 due to their particular shape and the good clamping of each seal 13. This further improves the uniformity of the current in all of the electrolysis cells 10.

[0224] The above assembly method is particularly characterized in that each seal 13: - the bipolar plates deform according to the geometric shape imposed by clamping each seal 13; - sinking into the texture of the first zone 21 to fill the texture; - intentionally prematurely aging the material from which the seal 13 is made; - eliminating as far as possible any plastic behavior of the material from which the seal 13 is made, - introducing a range of elastic behavior into the material (centered around the operating point of the electrolyzer stack); - Reaching the desired tightening value that achieves the desired sealing and electrical contact between the various components This makes it possible to achieve the expected energy performance.

[0225] At the end of the fourth step, the temperature and pressure prevailing inside the electrolyzer stack 1 may vary, but the seal advantageously always remains in the obtained elastic range. The nominal operating point of the electrolyzer stack is, for example, 85 degrees Celsius at 3 megapascals.

[0226] Naturally, the invention is not limited to the described embodiments, but includes any variant that is within the scope of the invention as defined in the claims.

[0227] The described assembly method is advantageously applicable to a variety of electrolyzer stacks 1, regardless of their thermal and mechanical properties, number, or size, or the nature of the materials forming said electrolyzer stack 1.

[0228] One or more of the end seals may be different from seal 13 .

[0229] The electrolyzer stack 1 can be assembled using methods different from those described.

[0230] Here, the electrolyzer stack is cooled (naturally and / or by forced cooling) to ambient temperature, but the electrolyzer stack can be cooled to a value greater than ambient temperature. For example, the electrolyzer stack can be cooled such that its temperature is less than 35 degrees Celsius, for example between 15 and 35 degrees Celsius, for example between 20 and 35 degrees Celsius. Thus, the low-temperature clamping can be performed at a different temperature between two successive low-temperature clamping operations and / or at a different temperature than the first clamping phase (where the electrolyzer stack is therefore at a temperature close to ambient, preferably below the high-temperature clamping temperature, without dropping below 15 degrees Celsius, which may impair the plasticity of the material of the seals).

[0231] The electrolyzer stack can be used horizontally, vertically or in any other configuration. The electrolyzer stack can be assembled horizontally, vertically or in any other configuration. Preferably, the electrolyzer stack is assembled vertically and used horizontally.

Claims

1. A bipolar plate (14) for an electrolysis cell (10), said bipolar plate (14) having on at least one of its major surfaces: a first zone (21) extending in the circumferential direction; a second zone (22) extending circumferentially so as to be bordered on the outside by said first zone (21), and which defines, together with said first zone (22), at least one narrowing of the thickness of said plate; a third zone (23) extending circumferentially so as to be bordered on the outside by said second zone (22), and which together with said second zone (22) defines at least one narrowing of the thickness of said plate; Equipped with The different zones (21, 22 and 23) are arranged on the periphery of the associated major surface. A bipolar plate (14) characterized in that:

2. 2. The bipolar plate (14) according to claim 1, characterized in that the first zone (21) is textured.

3. 3. The bipolar plate (14) of claim 2, wherein the textured first zone also extends circumferentially on another of the main surfaces of the bipolar plate (14).

4. 4. The bipolar plate (14) according to any one of claims 1 to 3, characterized in that the second zone (22) and / or the third zone (23) are not textured.

5. A bipolar plate (14) according to any one of claims 1 to 4, characterized in that it has a rounded outer periphery.

6. 6. The bipolar plate (14) according to any one of claims 2 to 5, characterized in that the first zone (21) comprises grooves.

7. 7. The bipolar plate (14) according to any one of claims 1 to 6, characterized in that the second zone (22) and the third zone (23) form at least two shoulders therebetween to provide a narrowing of the thickness of the plate.

8. 8. The bipolar plate (14) according to any one of claims 1 to 7, characterized in that at least three orifices are formed in the second zone (22).

9. 1. An electrolysis cell (10), comprising at least a first bipolar plate (14) according to any one of claims 1 to 8, at least a second bipolar plate (14) according to any one of claims 1 to 8, and a single seal (13) arranged between the two bipolar plates (14).

10. 10. The electrolysis cell (10) according to claim 9, characterized in that the seal (13) is made from a monomeric or polymeric material.

11. Electrolysis cell (10) according to claim 9 or 10, characterized in that the seal (13) is in the shape of a flat ring.

12. Electrolysis cell (10) according to any one of claims 9 to 11, characterized in that the seal (13) is made from a glass fibre reinforced material and / or a carbon fibre reinforced material.

13. 13. An electrolyzer stack (1), comprising a plurality of electrolysis cells (10) according to any one of claims 9 to 12.

14. A method for assembling an electrolyzer stack (1) according to claim 13, comprising the steps of: - individually assembling a set of electrolytic half-cells (10); - combining sets of said electrolytic half-cells (10) and placing seals between each set to form a block; - subjecting said block to successive heating and cooling phases and subjecting said block to at least one clamping action between two different heating and cooling phases; A method comprising:

15. 15. The method of claim 14, wherein the block is heated by injecting steam or hot water into the block to effect the clamping.

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